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Remove ase_test in structure LARCH_opts. #4

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Remove ase_test in structure LARCH_opts.

gas/config/tc-loongarch.c:
173:remove "LARCH_opts.ase_test = 1;".
249:remove "if" statement "if (LARCH_opts.ase_test) {...}".

include/opcode/loongarch.h:
190:remove "int ase_test;".

opcodes/loongarch-dis.c:
68:remove "LARCH_opts.ase_test = 1;".

opcodes/loongarch-opc.c:
23:remove ".ase_test = 0".

lzshhxx and others added 30 commits July 30, 2021 10:02
  bfd/Makefile.am
  bfd/Makefile.in
  bfd/archures.c
  bfd/bfd-in2.h
  bfd/config.bfd
  bfd/configure
  bfd/configure.ac
  bfd/cpu-loongarch.c
  bfd/elf-bfd.h
  bfd/elfnn-loongarch.c
  bfd/elfxx-loongarch.c
  bfd/elfxx-loongarch.h
  bfd/libbfd.h
  bfd/reloc.c
  bfd/targets.c
  binutils/readelf.c
  binutils/testsuite/binutils-all/objdump.exp
  gas/Makefile.am
  gas/Makefile.in
  gas/config/loongarch-lex-wrapper.c
  gas/config/loongarch-lex.l
  gas/config/loongarch-parse.y
  gas/config/tc-loongarch.c
  gas/config/tc-loongarch.h
  gas/configure
  gas/configure.ac
  gas/configure.tgt
  gas/testsuite/lib/gas-defs.exp
  include/dis-asm.h
  include/elf/loongarch.h
  include/opcode/loongarch.h
  ld/Makefile.am
  ld/Makefile.in
  ld/configure.tgt
  ld/emulparams/elf64loongarch-defs.sh
  ld/emulparams/elf64loongarch.sh
  ld/emultempl/loongarchelf.em
  opcodes/Makefile.am
  opcodes/Makefile.in
  opcodes/configure
  opcodes/configure.ac
  opcodes/disassemble.c
  opcodes/disassemble.h
  opcodes/loongarch-coder.c
  opcodes/loongarch-dis.c
  opcodes/loongarch-opc.c
  bfd/elf.c
  gdb/Makefile.in
  gdb/arch/loongarch-linux-nat.c
  gdb/arch/loongarch-linux-nat.h
  gdb/arch/loongarch.c
  gdb/arch/loongarch.h
  gdb/configure.host
  gdb/configure.nat
  gdb/configure.tgt
  gdb/corelow.c
  gdb/features/Makefile
  gdb/features/loongarch/base32.c
  gdb/features/loongarch/base32.xml
  gdb/features/loongarch/base64.c
  gdb/features/loongarch/base64.xml
  gdb/features/loongarch/fpu32.c
  gdb/features/loongarch/fpu32.xml
  gdb/features/loongarch/fpu64.c
  gdb/features/loongarch/fpu64.xml
  gdb/features/loongarch/lasx.c
  gdb/features/loongarch/lasx.xml
  gdb/features/loongarch/lbt32.c
  gdb/features/loongarch/lbt32.xml
  gdb/features/loongarch/lbt64.c
  gdb/features/loongarch/lbt64.xml
  gdb/features/loongarch/lsx.c
  gdb/features/loongarch/lsx.xml
  gdb/loongarch-linux-nat.c
  gdb/loongarch-linux-tdep.c
  gdb/loongarch-linux-tdep.h
  gdb/loongarch-tdep.c
  gdb/loongarch-tdep.h
  gdb/nat/loongarch-linux-watch.c
  gdb/nat/loongarch-linux-watch.h
  gdb/remote.c
  gdb/target.h
  gdb/testsuite/gdb.base/dump.exp
  gdb/testsuite/gdb.base/float.exp
  gdb/testsuite/gdb.trace/entry-values.exp
  gdb/testsuite/gdb.xml/tdesc-regs.exp
  include/elf/common.h
  gdbserver/Makefile.in
  gdbserver/configure.srv
  gdbserver/linux-loongarch-low.cc
    opcodes/
    * loongarch-opc.c (loongarch_jmp_opcodes): Add "b" insn.
  gdb/loongarch-linux-tdep.h
  gas/config/loongarch-parse.y
  gas/config/tc-loongarch.c
  opcodes/loongarch-dis.c
When building with gcc 10.2.1, the build fails with:

```
elfnn-loongarch.c: In function ‘loongarch_elf_relocate_section’:
elfnn-loongarch.c:1470:29: error: ‘opr1’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
elfnn-loongarch.c:1445:11: note: ‘opr1’ was declared here
cc1: all warnings being treated as errors
```

This commit fixes incorrect logic to become: `loongarch_pop` does not succeed or the assertion check failed.
 include/elf/common.h
  bfd/cpu-loongarch.c
  bfd/elfnn-loongarch.c
  bfd/elfxx-loongarch.c
  gas/NEWS
  gas/config/loongarch-parse.y
  gas/config/tc-loongarch.c
  gas/config/tc-loongarch.h
  gas/doc/as.texi
  gas/doc/c-loongarch.texi
  gas/testsuite/gas/loongarch/loongarch.exp
  gas/testsuite/gas/loongarch/nop.d
  gas/testsuite/gas/loongarch/nop.s
  gdb/arch/loongarch-linux-nat.c
  gdb/loongarch-linux-nat.c
  gdb/loongarch-linux-tdep.c
  gdb/loongarch-linux-tdep.h
  gdb/loongarch-tdep.c
  gdbserver/linux-loongarch-low.cc
  include/elf/loongarch.h
  include/opcode/loongarch.h
  ld/NEWS
  opcodes/loongarch-coder.c
  opcodes/loongarch-dis.c
  opcodes/loongarch-opc.c
bfd/elfxx-loongarch.c:
	change "loong_reloc_map" into "larch_reloc_map"
include/elf/loongarch.h:
	change "_ELF_LOONG_H" into "_ELF_LOONGARCH_H"
ld/emultempl/loongarchelf.em:
	change "loong_elf_before_allocation" into "larch_elf_before_allocation"
	change "loong_create_output_section_statements" into "larch_create_output_section_statements"
  bfd/cpu-loongarch.c
  bfd/elfnn-loongarch.c
  bfd/elfxx-loongarch.c
  bfd/elfxx-loongarch.h
  gas/config/loongarch-lex-wrapper.c
  gas/config/loongarch-lex.l
  gas/config/loongarch-parse.y
  gas/config/tc-loongarch.c
  gas/config/tc-loongarch.h
  gdb/arch/loongarch-linux-nat.h
  gdb/arch/loongarch.c
  gdb/loongarch-linux-nat.c
  gdb/loongarch-linux-tdep.c
  gdb/loongarch-linux-tdep.h
  gdb/loongarch-tdep.c
  gdb/loongarch-tdep.h
  gdb/nat/loongarch-linux-watch.c
  gdb/nat/loongarch-linux-watch.h
  gdbserver/linux-loongarch-low.cc
  include/elf/loongarch.h
  include/opcode/loongarch.h
  ld/emultempl/loongarchelf.em
  opcodes/loongarch-coder.c
  opcodes/loongarch-dis.c
  opcodes/loongarch-opc.c
  bfd/config.bfd
  bfd/configure
  bfd/elfnn-loongarch.c
  gas/config/tc-loongarch.c
  gdb/arch/loongarch-linux-nat.c
  gdb/arch/loongarch.h
  gdb/configure.nat
  gdb/loongarch-linux-tdep.c
  gdb/loongarch-tdep.c
  gdb/remote.c
  gdb/testsuite/gdb.xml/tdesc-regs.exp
  bfd/cpu-loongarch.c
  bfd/elfnn-loongarch.c
  bfd/elfxx-loongarch.c
  bfd/elfxx-loongarch.h
  gas/config/loongarch-lex-wrapper.c
  gas/config/loongarch-lex.l
  gas/config/loongarch-parse.y
  gas/config/tc-loongarch.c
  gas/config/tc-loongarch.h
  gas/doc/c-loongarch.texi
  gas/testsuite/gas/loongarch/loongarch.exp
  gdb/arch/loongarch-linux-nat.c
  gdb/arch/loongarch-linux-nat.h
  gdb/arch/loongarch.c
  gdb/arch/loongarch.h
  gdb/features/loongarch/base32.xml
  gdb/features/loongarch/base64.xml
  gdb/features/loongarch/fpu32.xml
  gdb/features/loongarch/fpu64.xml
  gdb/features/loongarch/lasx.xml
  gdb/features/loongarch/lbt32.xml
  gdb/features/loongarch/lbt64.xml
  gdb/features/loongarch/lsx.xml
  gdb/loongarch-linux-nat.c
  gdb/loongarch-linux-tdep.c
  gdb/loongarch-linux-tdep.h
  gdb/loongarch-tdep.c
  bfd/archures.c
  bfd/bfd-in2.h
  bfd/cpu-loongarch.c
  bfd/elfnn-loongarch.c
  bfd/elfxx-loongarch.c
  bfd/elfxx-loongarch.h
  gas/Makefile.am
  gas/Makefile.in
  gas/config/tc-loongarch.c
  gdb/configure.nat
  gdb/loongarch-linux-nat.c
  gdb/loongarch-linux-tdep.c
  gdb/loongarch-linux-tdep.h
  gdb/loongarch-tdep.c
  gdb/loongarch-tdep.h
  include/elf/common.h
  include/opcode/loongarch.h
  opcodes/disassemble.c
  opcodes/loongarch-coder.c
  opcodes/loongarch-dis.c
  opcodes/loongarch-opc.c
  bfd/elfxx-loongarch.c
  gdb/nat/loongarch-linux-watch.c
  gdb/nat/loongarch-linux-watch.h
  include/elf/loongarch.h
  bfd/elfnn-loongarch.c
  gdb/loongarch-tdep.c
  gas/config/tc-loongarch.c
  gas/testsuite/gas/all/gas.exp
mikpe pushed a commit to mikpe/binutils-gdb that referenced this pull request Aug 5, 2023
…s_debug_type}

With gdb build with -fsanitize=thread and test-case gdb.base/index-cache.exp
and target board debug-types, I run into:
...
(gdb) file build/gdb/testsuite/outputs/gdb.base/index-cache/index-cache
Reading symbols from build/gdb/testsuite/outputs/gdb.base/index-cache/index-cache...
==================
WARNING: ThreadSanitizer: data race (pid=9654)
  Write of size 1 at 0x7b200000420d by main thread:
    #0 dwarf2_per_cu_data::get_header() const gdb/dwarf2/read.c:21513 (gdb+0x8d1eee)
    bminor#1 dwarf2_per_cu_data::addr_size() const gdb/dwarf2/read.c:21524 (gdb+0x8d1f4e)
    bminor#2 dwarf2_cu::addr_type() const gdb/dwarf2/cu.c:112 (gdb+0x806327)
    bminor#3 set_die_type gdb/dwarf2/read.c:21932 (gdb+0x8d3870)
    bminor#4 read_base_type gdb/dwarf2/read.c:15448 (gdb+0x8bcacb)
    bminor#5 read_type_die_1 gdb/dwarf2/read.c:19832 (gdb+0x8cc0a5)
    bminor#6 read_type_die gdb/dwarf2/read.c:19767 (gdb+0x8cbe6d)
    bminor#7 lookup_die_type gdb/dwarf2/read.c:19739 (gdb+0x8cbdc7)
    bminor#8 die_type gdb/dwarf2/read.c:19593 (gdb+0x8cb68a)
    bminor#9 read_subroutine_type gdb/dwarf2/read.c:14648 (gdb+0x8b998e)
    bminor#10 read_type_die_1 gdb/dwarf2/read.c:19792 (gdb+0x8cbf2f)
    bminor#11 read_type_die gdb/dwarf2/read.c:19767 (gdb+0x8cbe6d)
    bminor#12 read_func_scope gdb/dwarf2/read.c:10154 (gdb+0x8a4f36)
    #13 process_die gdb/dwarf2/read.c:6667 (gdb+0x898daa)
    #14 read_file_scope gdb/dwarf2/read.c:7682 (gdb+0x89bad8)
    #15 process_die gdb/dwarf2/read.c:6654 (gdb+0x898ced)
    #16 process_full_comp_unit gdb/dwarf2/read.c:6418 (gdb+0x8981de)
    #17 process_queue gdb/dwarf2/read.c:5690 (gdb+0x894433)
    #18 dw2_do_instantiate_symtab gdb/dwarf2/read.c:1770 (gdb+0x88623a)
    #19 dw2_instantiate_symtab gdb/dwarf2/read.c:1792 (gdb+0x886300)
    #20 dw2_expand_symtabs_matching_one(dwarf2_per_cu_data*, dwarf2_per_objfile*, gdb::function_view<bool (char const*, bool)>, gdb::function_view<bool (compunit_symtab*)>) gdb/dwarf2/read.c:3042 (gdb+0x88b1f1)
    #21 cooked_index_functions::expand_symtabs_matching(objfile*, gdb::function_view<bool (char const*, bool)>, lookup_name_info const*, gdb::function_view<bool (char const*)>, gdb::function_view<bool (compunit_symtab*)>, enum_flags<block_search_flag_values>, domain_enum, search_domain) gdb/dwarf2/read.c:16917 (gdb+0x8c228e)
    #22 objfile::lookup_symbol(block_enum, char const*, domain_enum) gdb/symfile-debug.c:288 (gdb+0xf39055)
    #23 lookup_symbol_via_quick_fns gdb/symtab.c:2385 (gdb+0xf66ab7)
    #24 lookup_symbol_in_objfile gdb/symtab.c:2516 (gdb+0xf6711b)
    #25 operator() gdb/symtab.c:2562 (gdb+0xf67272)
    #26 operator() gdb/../gdbsupport/function-view.h:305 (gdb+0xf776b1)
    #27 _FUN gdb/../gdbsupport/function-view.h:299 (gdb+0xf77708)
    #28 gdb::function_view<bool (objfile*)>::operator()(objfile*) const gdb/../gdbsupport/function-view.h:289 (gdb+0xc3fc97)
    #29 svr4_iterate_over_objfiles_in_search_order gdb/solib-svr4.c:3455 (gdb+0xecae47)
    #30 gdbarch_iterate_over_objfiles_in_search_order(gdbarch*, gdb::function_view<bool (objfile*)>, objfile*) gdb/gdbarch.c:5041 (gdb+0x537cad)
    #31 lookup_global_or_static_symbol gdb/symtab.c:2559 (gdb+0xf674fb)
    #32 lookup_global_symbol(char const*, block const*, domain_enum) gdb/symtab.c:2615 (gdb+0xf67780)
    #33 language_defn::lookup_symbol_nonlocal(char const*, block const*, domain_enum) const gdb/symtab.c:2447 (gdb+0xf66d6e)
    #34 lookup_symbol_aux gdb/symtab.c:2123 (gdb+0xf65cb3)
    #35 lookup_symbol_in_language(char const*, block const*, domain_enum, language, field_of_this_result*) gdb/symtab.c:1931 (gdb+0xf64dab)
    #36 set_initial_language() gdb/symfile.c:1708 (gdb+0xf43074)
    #37 symbol_file_add_main_1 gdb/symfile.c:1212 (gdb+0xf41608)
    #38 symbol_file_command(char const*, int) gdb/symfile.c:1681 (gdb+0xf42faf)
    #39 file_command gdb/exec.c:554 (gdb+0x94ff29)
    #40 do_simple_func gdb/cli/cli-decode.c:95 (gdb+0x6d9528)
    #41 cmd_func(cmd_list_element*, char const*, int) gdb/cli/cli-decode.c:2735 (gdb+0x6e0f69)
    #42 execute_command(char const*, int) gdb/top.c:575 (gdb+0xff379c)
    #43 command_handler(char const*) gdb/event-top.c:552 (gdb+0x94b5bc)
    #44 command_line_handler(std::unique_ptr<char, gdb::xfree_deleter<char> >&&) gdb/event-top.c:788 (gdb+0x94bc79)
    #45 tui_command_line_handler gdb/tui/tui-interp.c:104 (gdb+0x1034efc)
    #46 gdb_rl_callback_handler gdb/event-top.c:259 (gdb+0x94ab61)
    #47 rl_callback_read_char readline/readline/callback.c:290 (gdb+0x11be4ef)
    #48 gdb_rl_callback_read_char_wrapper_noexcept gdb/event-top.c:195 (gdb+0x94a960)
    #49 gdb_rl_callback_read_char_wrapper gdb/event-top.c:234 (gdb+0x94aa21)
    #50 stdin_event_handler gdb/ui.c:155 (gdb+0x10751a0)
    #51 handle_file_event gdbsupport/event-loop.cc:573 (gdb+0x1d95bac)
    #52 gdb_wait_for_event gdbsupport/event-loop.cc:694 (gdb+0x1d962e4)
    #53 gdb_do_one_event(int) gdbsupport/event-loop.cc:264 (gdb+0x1d946d0)
    #54 start_event_loop gdb/main.c:412 (gdb+0xb5ab52)
    #55 captured_command_loop gdb/main.c:476 (gdb+0xb5ad41)
    #56 captured_main gdb/main.c:1320 (gdb+0xb5cec1)
    #57 gdb_main(captured_main_args*) gdb/main.c:1339 (gdb+0xb5cf70)
    #58 main gdb/gdb.c:32 (gdb+0x416776)

  Previous read of size 1 at 0x7b200000420d by thread T11:
    #0 write_gdbindex gdb/dwarf2/index-write.c:1229 (gdb+0x831630)
    bminor#1 write_dwarf_index(dwarf2_per_bfd*, char const*, char const*, char const*, dw_index_kind) gdb/dwarf2/index-write.c:1484 (gdb+0x832897)
    bminor#2 index_cache::store(dwarf2_per_bfd*, index_cache_store_context const&) gdb/dwarf2/index-cache.c:173 (gdb+0x82db8d)
    bminor#3 cooked_index::maybe_write_index(dwarf2_per_bfd*, index_cache_store_context const&) gdb/dwarf2/cooked-index.c:645 (gdb+0x7f1d49)
    bminor#4 operator() gdb/dwarf2/cooked-index.c:474 (gdb+0x7f0f31)
    bminor#5 _M_invoke /usr/include/c++/7/bits/std_function.h:316 (gdb+0x7f2a13)
    bminor#6 std::function<void ()>::operator()() const /usr/include/c++/7/bits/std_function.h:706 (gdb+0x700952)
    bminor#7 void std::__invoke_impl<void, std::function<void ()>&>(std::__invoke_other, std::function<void ()>&) /usr/include/c++/7/bits/invoke.h:60 (gdb+0x7381a0)
    bminor#8 std::__invoke_result<std::function<void ()>&>::type std::__invoke<std::function<void ()>&>(std::function<void ()>&) /usr/include/c++/7/bits/invoke.h:95 (gdb+0x737e91)
    bminor#9 std::__future_base::_Task_state<std::function<void ()>, std::allocator<int>, void ()>::_M_run()::{lambda()bminor#1}::operator()() const /usr/include/c++/7/future:1421 (gdb+0x737b59)
    bminor#10 std::__future_base::_Task_setter<std::unique_ptr<std::__future_base::_Result<void>, std::__future_base::_Result_base::_Deleter>, std::__future_base::_Task_state<std::function<void ()>, std::allocator<int>, void ()>::_M_run()::{lambda()bminor#1}, void>::operator()() const /usr/include/c++/7/future:1362 (gdb+0x738660)
    bminor#11 std::_Function_handler<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> (), std::__future_base::_Task_setter<std::unique_ptr<std::__future_base::_Result<void>, std::__future_base::_Result_base::_Deleter>, std::__future_base::_Task_state<std::function<void ()>, std::allocator<int>, void ()>::_M_run()::{lambda()bminor#1}, void> >::_M_invoke(std::_Any_data const&) /usr/include/c++/7/bits/std_function.h:302 (gdb+0x73825c)
    bminor#12 std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>::operator()() const /usr/include/c++/7/bits/std_function.h:706 (gdb+0x733623)
    #13 std::__future_base::_State_baseV2::_M_do_set(std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*) /usr/include/c++/7/future:561 (gdb+0x732bdf)
    #14 void std::__invoke_impl<void, void (std::__future_base::_State_baseV2::*)(std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*), std::__future_base::_State_baseV2*, std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*>(std::__invoke_memfun_deref, void (std::__future_base::_State_baseV2::*&&)(std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*), std::__future_base::_State_baseV2*&&, std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*&&, bool*&&) /usr/include/c++/7/bits/invoke.h:73 (gdb+0x734c4f)
    #15 std::__invoke_result<void (std::__future_base::_State_baseV2::*)(std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*), std::__future_base::_State_baseV2*, std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*>::type std::__invoke<void (std::__future_base::_State_baseV2::*)(std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*), std::__future_base::_State_baseV2*, std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*>(void (std::__future_base::_State_baseV2::*&&)(std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*), std::__future_base::_State_baseV2*&&, std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*&&, bool*&&) /usr/include/c++/7/bits/invoke.h:95 (gdb+0x733bc5)
    #16 std::call_once<void (std::__future_base::_State_baseV2::*)(std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*), std::__future_base::_State_baseV2*, std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*>(std::once_flag&, void (std::__future_base::_State_baseV2::*&&)(std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*), std::__future_base::_State_baseV2*&&, std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*&&, bool*&&)::{lambda()bminor#1}::operator()() const /usr/include/c++/7/mutex:672 (gdb+0x73300d)
    #17 std::call_once<void (std::__future_base::_State_baseV2::*)(std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*), std::__future_base::_State_baseV2*, std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*>(std::once_flag&, void (std::__future_base::_State_baseV2::*&&)(std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*), std::__future_base::_State_baseV2*&&, std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*&&, bool*&&)::{lambda()bminor#2}::operator()() const /usr/include/c++/7/mutex:677 (gdb+0x7330b2)
    #18 std::call_once<void (std::__future_base::_State_baseV2::*)(std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*), std::__future_base::_State_baseV2*, std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*>(std::once_flag&, void (std::__future_base::_State_baseV2::*&&)(std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*), std::__future_base::_State_baseV2*&&, std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*&&, bool*&&)::{lambda()bminor#2}::_FUN() /usr/include/c++/7/mutex:677 (gdb+0x7330f2)
    #19 pthread_once <null> (libtsan.so.0+0x4457c)
    #20 __gthread_once /usr/include/c++/7/x86_64-suse-linux/bits/gthr-default.h:699 (gdb+0x72f5dd)
    #21 void std::call_once<void (std::__future_base::_State_baseV2::*)(std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*), std::__future_base::_State_baseV2*, std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*>(std::once_flag&, void (std::__future_base::_State_baseV2::*&&)(std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*), std::__future_base::_State_baseV2*&&, std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*&&, bool*&&) /usr/include/c++/7/mutex:684 (gdb+0x733224)
    #22 std::__future_base::_State_baseV2::_M_set_result(std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>, bool) /usr/include/c++/7/future:401 (gdb+0x732852)
    #23 std::__future_base::_Task_state<std::function<void ()>, std::allocator<int>, void ()>::_M_run() /usr/include/c++/7/future:1423 (gdb+0x737bef)
    #24 std::packaged_task<void ()>::operator()() /usr/include/c++/7/future:1556 (gdb+0x1dad25a)
    #25 gdb::thread_pool::thread_function() gdbsupport/thread-pool.cc:242 (gdb+0x1dacb7c)
    #26 void std::__invoke_impl<void, void (gdb::thread_pool::*)(), gdb::thread_pool*>(std::__invoke_memfun_deref, void (gdb::thread_pool::*&&)(), gdb::thread_pool*&&) /usr/include/c++/7/bits/invoke.h:73 (gdb+0x1dadc2b)
    #27 std::__invoke_result<void (gdb::thread_pool::*)(), gdb::thread_pool*>::type std::__invoke<void (gdb::thread_pool::*)(), gdb::thread_pool*>(void (gdb::thread_pool::*&&)(), gdb::thread_pool*&&) /usr/include/c++/7/bits/invoke.h:95 (gdb+0x1dad05c)
    #28 decltype (__invoke((_S_declval<0ul>)(), (_S_declval<1ul>)())) std::thread::_Invoker<std::tuple<void (gdb::thread_pool::*)(), gdb::thread_pool*> >::_M_invoke<0ul, 1ul>(std::_Index_tuple<0ul, 1ul>) /usr/include/c++/7/thread:234 (gdb+0x1db038e)
    #29 std::thread::_Invoker<std::tuple<void (gdb::thread_pool::*)(), gdb::thread_pool*> >::operator()() /usr/include/c++/7/thread:243 (gdb+0x1db0319)
    #30 std::thread::_State_impl<std::thread::_Invoker<std::tuple<void (gdb::thread_pool::*)(), gdb::thread_pool*> > >::_M_run() /usr/include/c++/7/thread:186 (gdb+0x1db02ce)
    #31 <null> <null> (libstdc++.so.6+0xdcac2)
  ...
SUMMARY: ThreadSanitizer: data race gdb/dwarf2/read.c:21513 in dwarf2_per_cu_data::get_header() const
...

The race happens when issuing the "file $exec" command.

The race is between:
- a worker thread writing the index cache, and in the process reading
   dwarf2_per_cu_data::is_debug_type, and
- the main thread writing to dwarf2_per_cu_data::m_header_read_in.

The two bitfields dwarf2_per_cu_data::m_header_read_in and
dwarf2_per_cu_data::is_debug_type share the same bitfield container.

Fix this by making dwarf2_per_cu_data::m_header_read_in a packed<bool, 1>.

Tested on x86_64-linux.

Approved-By: Tom Tromey <tom@tromey.com>

PR symtab/30392
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=30392
mikpe pushed a commit to mikpe/binutils-gdb that referenced this pull request Aug 5, 2023
With gdb build with -fsanitize=thread, and the exec from test-case
gdb.base/index-cache.exp, I run into:
...
$ rm -f ~/.cache/gdb/*; \
  gdb -q -batch -iex "set index-cache enabled on" index-cache \
    -ex "print foobar"
  ...
WARNING: ThreadSanitizer: data race (pid=23970)
  Write of size 1 at 0x7b200000410d by main thread:
    #0 dw_expand_symtabs_matching_file_matcher(dwarf2_per_objfile*, gdb::function_view<bool (char const*, bool)>) gdb/dwarf2/read.c:3077 (gdb+0x7ac54e)
    bminor#1 cooked_index_functions::expand_symtabs_matching(objfile*, gdb::function_view<bool (char const*, bool)>, lookup_name_info const*, gdb::function_view<bool (char const*)>, gdb::function_view<bool (compunit_symtab*)>, enum_flags<block_search_flag_values>, domain_enum, search_domain) gdb/dwarf2/read.c:16812 (gdb+0x7d039f)
    bminor#2 objfile::map_symtabs_matching_filename(char const*, char const*, gdb::function_view<bool (symtab*)>) gdb/symfile-debug.c:219 (gdb+0xda5aee)
    bminor#3 iterate_over_symtabs(char const*, gdb::function_view<bool (symtab*)>) gdb/symtab.c:648 (gdb+0xdc439d)
    bminor#4 lookup_symtab(char const*) gdb/symtab.c:662 (gdb+0xdc44a2)
    bminor#5 classify_name gdb/c-exp.y:3083 (gdb+0x61afec)
    bminor#6 c_yylex gdb/c-exp.y:3251 (gdb+0x61dd13)
    bminor#7 c_yyparse() build/gdb/c-exp.c.tmp:1988 (gdb+0x61f07e)
    bminor#8 c_parse(parser_state*) gdb/c-exp.y:3417 (gdb+0x62d864)
    bminor#9 language_defn::parser(parser_state*) const gdb/language.c:598 (gdb+0x9771c5)
    bminor#10 parse_exp_in_context gdb/parse.c:414 (gdb+0xb10a9b)
    bminor#11 parse_expression(char const*, innermost_block_tracker*, enum_flags<parser_flag>) gdb/parse.c:462 (gdb+0xb110ae)
    bminor#12 process_print_command_args gdb/printcmd.c:1321 (gdb+0xb4bf0c)
    #13 print_command_1 gdb/printcmd.c:1335 (gdb+0xb4ca2a)
    #14 print_command gdb/printcmd.c:1468 (gdb+0xb4cd5a)
    #15 do_simple_func gdb/cli/cli-decode.c:95 (gdb+0x65b078)
    #16 cmd_func(cmd_list_element*, char const*, int) gdb/cli/cli-decode.c:2735 (gdb+0x65ed53)
    #17 execute_command(char const*, int) gdb/top.c:575 (gdb+0xe3a76a)
    #18 catch_command_errors gdb/main.c:518 (gdb+0xa1837d)
    #19 execute_cmdargs gdb/main.c:617 (gdb+0xa1853f)
    #20 captured_main_1 gdb/main.c:1289 (gdb+0xa1aa58)
    #21 captured_main gdb/main.c:1310 (gdb+0xa1b95a)
    #22 gdb_main(captured_main_args*) gdb/main.c:1339 (gdb+0xa1b95a)
    #23 main gdb/gdb.c:39 (gdb+0x42506a)

  Previous read of size 1 at 0x7b200000410d by thread T1:
    #0 write_gdbindex gdb/dwarf2/index-write.c:1214 (gdb+0x75bb30)
    bminor#1 write_dwarf_index(dwarf2_per_bfd*, char const*, char const*, char const*, dw_index_kind) gdb/dwarf2/index-write.c:1469 (gdb+0x75f803)
    bminor#2 index_cache::store(dwarf2_per_bfd*, index_cache_store_context const&) gdb/dwarf2/index-cache.c:173 (gdb+0x755a36)
    bminor#3 cooked_index::maybe_write_index(dwarf2_per_bfd*, index_cache_store_context const&) gdb/dwarf2/cooked-index.c:642 (gdb+0x71c96d)
    bminor#4 operator() gdb/dwarf2/cooked-index.c:471 (gdb+0x71c96d)
    bminor#5 _M_invoke /usr/include/c++/7/bits/std_function.h:316 (gdb+0x71c96d)
    bminor#6 std::function<void ()>::operator()() const /usr/include/c++/7/bits/std_function.h:706 (gdb+0x72a57c)
    bminor#7 void std::__invoke_impl<void, std::function<void ()>&>(std::__invoke_other, std::function<void ()>&) /usr/include/c++/7/bits/invoke.h:60 (gdb+0x72a5db)
    bminor#8 std::__invoke_result<std::function<void ()>&>::type std::__invoke<std::function<void ()>&>(std::function<void ()>&) /usr/include/c++/7/bits/invoke.h:95 (gdb+0x72a5db)
    bminor#9 std::__future_base::_Task_state<std::function<void ()>, std::allocator<int>, void ()>::_M_run()::{lambda()bminor#1}::operator()() const /usr/include/c++/7/future:1421 (gdb+0x72a5db)
    bminor#10 std::__future_base::_Task_setter<std::unique_ptr<std::__future_base::_Result<void>, std::__future_base::_Result_base::_Deleter>, std::__future_base::_Task_state<std::function<void ()>, std::allocator<int>, void ()>::_M_run()::{lambda()bminor#1}, void>::operator()() const /usr/include/c++/7/future:1362 (gdb+0x72a5db)
    bminor#11 std::_Function_handler<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> (), std::__future_base::_Task_setter<std::unique_ptr<std::__future_base::_Result<void>, std::__future_base::_Result_base::_Deleter>, std::__future_base::_Task_state<std::function<void ()>, std::allocator<int>, void ()>::_M_run()::{lambda()bminor#1}, void> >::_M_invoke(std::_Any_data const&) /usr/include/c++/7/bits/std_function.h:302 (gdb+0x72a5db)
    bminor#12 std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>::operator()() const /usr/include/c++/7/bits/std_function.h:706 (gdb+0x724954)
    #13 std::__future_base::_State_baseV2::_M_do_set(std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*) /usr/include/c++/7/future:561 (gdb+0x724954)
    #14 void std::__invoke_impl<void, void (std::__future_base::_State_baseV2::*)(std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*), std::__future_base::_State_baseV2*, std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*>(std::__invoke_memfun_deref, void (std::__future_base::_State_baseV2::*&&)(std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*), std::__future_base::_State_baseV2*&&, std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*&&, bool*&&) /usr/include/c++/7/bits/invoke.h:73 (gdb+0x72434a)
    #15 std::__invoke_result<void (std::__future_base::_State_baseV2::*)(std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*), std::__future_base::_State_baseV2*, std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*>::type std::__invoke<void (std::__future_base::_State_baseV2::*)(std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*), std::__future_base::_State_baseV2*, std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*>(void (std::__future_base::_State_baseV2::*&&)(std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*), std::__future_base::_State_baseV2*&&, std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*&&, bool*&&) /usr/include/c++/7/bits/invoke.h:95 (gdb+0x72434a)
    #16 std::call_once<void (std::__future_base::_State_baseV2::*)(std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*), std::__future_base::_State_baseV2*, std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*>(std::once_flag&, void (std::__future_base::_State_baseV2::*&&)(std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*), std::__future_base::_State_baseV2*&&, std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*&&, bool*&&)::{lambda()bminor#1}::operator()() const /usr/include/c++/7/mutex:672 (gdb+0x72434a)
    #17 std::call_once<void (std::__future_base::_State_baseV2::*)(std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*), std::__future_base::_State_baseV2*, std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*>(std::once_flag&, void (std::__future_base::_State_baseV2::*&&)(std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*), std::__future_base::_State_baseV2*&&, std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*&&, bool*&&)::{lambda()bminor#2}::operator()() const /usr/include/c++/7/mutex:677 (gdb+0x72434a)
    #18 std::call_once<void (std::__future_base::_State_baseV2::*)(std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*), std::__future_base::_State_baseV2*, std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*>(std::once_flag&, void (std::__future_base::_State_baseV2::*&&)(std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*), std::__future_base::_State_baseV2*&&, std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*&&, bool*&&)::{lambda()bminor#2}::_FUN() /usr/include/c++/7/mutex:677 (gdb+0x72434a)
    #19 pthread_once <null> (libtsan.so.0+0x4457c)
    #20 __gthread_once /usr/include/c++/7/x86_64-suse-linux/bits/gthr-default.h:699 (gdb+0x72532b)
    #21 void std::call_once<void (std::__future_base::_State_baseV2::*)(std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*), std::__future_base::_State_baseV2*, std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*>(std::once_flag&, void (std::__future_base::_State_baseV2::*&&)(std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*), std::__future_base::_State_baseV2*&&, std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*&&, bool*&&) /usr/include/c++/7/mutex:684 (gdb+0x72532b)
    #22 std::__future_base::_State_baseV2::_M_set_result(std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>, bool) /usr/include/c++/7/future:401 (gdb+0x174568d)
    #23 std::__future_base::_Task_state<std::function<void ()>, std::allocator<int>, void ()>::_M_run() /usr/include/c++/7/future:1423 (gdb+0x174568d)
    #24 std::packaged_task<void ()>::operator()() /usr/include/c++/7/future:1556 (gdb+0x174568d)
    #25 gdb::thread_pool::thread_function() gdbsupport/thread-pool.cc:242 (gdb+0x174568d)
    #26 void std::__invoke_impl<void, void (gdb::thread_pool::*)(), gdb::thread_pool*>(std::__invoke_memfun_deref, void (gdb::thread_pool::*&&)(), gdb::thread_pool*&&) /usr/include/c++/7/bits/invoke.h:73 (gdb+0x1748040)
    #27 std::__invoke_result<void (gdb::thread_pool::*)(), gdb::thread_pool*>::type std::__invoke<void (gdb::thread_pool::*)(), gdb::thread_pool*>(void (gdb::thread_pool::*&&)(), gdb::thread_pool*&&) /usr/include/c++/7/bits/invoke.h:95 (gdb+0x1748040)
    #28 decltype (__invoke((_S_declval<0ul>)(), (_S_declval<1ul>)())) std::thread::_Invoker<std::tuple<void (gdb::thread_pool::*)(), gdb::thread_pool*> >::_M_invoke<0ul, 1ul>(std::_Index_tuple<0ul, 1ul>) /usr/include/c++/7/thread:234 (gdb+0x1748040)
    #29 std::thread::_Invoker<std::tuple<void (gdb::thread_pool::*)(), gdb::thread_pool*> >::operator()() /usr/include/c++/7/thread:243 (gdb+0x1748040)
    #30 std::thread::_State_impl<std::thread::_Invoker<std::tuple<void (gdb::thread_pool::*)(), gdb::thread_pool*> > >::_M_run() /usr/include/c++/7/thread:186 (gdb+0x1748040)
    #31 <null> <null> (libstdc++.so.6+0xdcac2)
  ...
SUMMARY: ThreadSanitizer: data race gdb/dwarf2/read.c:3077 in dw_expand_symtabs_matching_file_matcher(dwarf2_per_objfile*, gdb::function_view<bool (char const*, bool)>)
...

The race happens when issuing the "file $exec" command.

The race is between:
- a worker thread writing the index cache, and in the process reading
  dwarf2_per_cu_data::is_debug_type, and
- the main thread writing to dwarf2_per_cu_data::mark.

The two bitfields dwarf2_per_cu_data::mark and
dwarf2_per_cu_data::is_debug_type share the same bitfield container.

Fix this by making dwarf2_per_cu_data::mark a packed<unsigned int, 1>.

Tested on x86_64-linux.

PR symtab/30718
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=30718
mikpe pushed a commit to mikpe/binutils-gdb that referenced this pull request Aug 5, 2023
…g_types}

With gdb build with -fsanitize=thread, and the exec from test-case
gdb.base/index-cache.exp, I run into:
...
$ rm -f ~/.cache/gdb/*; \
  gdb -q -batch -iex "set index-cache enabled on" index-cache \
    -ex "print foobar"
  ...
WARNING: ThreadSanitizer: data race (pid=25018)
  Write of size 1 at 0x7b200000410d by main thread:
    #0 dw2_get_file_names_reader gdb/dwarf2/read.c:2033 (gdb+0x7ab023)
    bminor#1 dw2_get_file_names gdb/dwarf2/read.c:2130 (gdb+0x7ab023)
    bminor#2 dw_expand_symtabs_matching_file_matcher(dwarf2_per_objfile*, gdb::function_view<bool (char const*, bool)>) gdb/dwarf2/read.c:3105 (gdb+0x7ac6e9)
    bminor#3 cooked_index_functions::expand_symtabs_matching(objfile*, gdb::function_view<bool (char const*, bool)>, lookup_name_info const*, gdb::function_view<bool (char const*)>, gdb::function_view<bool (compunit_symtab*)>, enum_flags<block_search_flag_values>, domain_enum, search_domain) gdb/dwarf2/read.c:16812 (gdb+0x7d040f)
    bminor#4 objfile::map_symtabs_matching_filename(char const*, char const*, gdb::function_view<bool (symtab*)>) gdb/symfile-debug.c:219 (gdb+0xda5b6e)
    bminor#5 iterate_over_symtabs(char const*, gdb::function_view<bool (symtab*)>) gdb/symtab.c:648 (gdb+0xdc441d)
    bminor#6 lookup_symtab(char const*) gdb/symtab.c:662 (gdb+0xdc4522)
    bminor#7 classify_name gdb/c-exp.y:3083 (gdb+0x61afec)
    bminor#8 c_yylex gdb/c-exp.y:3251 (gdb+0x61dd13)
    bminor#9 c_yyparse() build/gdb/c-exp.c.tmp:1988 (gdb+0x61f07e)
    bminor#10 c_parse(parser_state*) gdb/c-exp.y:3417 (gdb+0x62d864)
    bminor#11 language_defn::parser(parser_state*) const gdb/language.c:598 (gdb+0x977245)
    bminor#12 parse_exp_in_context gdb/parse.c:414 (gdb+0xb10b1b)
    #13 parse_expression(char const*, innermost_block_tracker*, enum_flags<parser_flag>) gdb/parse.c:462 (gdb+0xb1112e)
    #14 process_print_command_args gdb/printcmd.c:1321 (gdb+0xb4bf8c)
    #15 print_command_1 gdb/printcmd.c:1335 (gdb+0xb4caaa)
    #16 print_command gdb/printcmd.c:1468 (gdb+0xb4cdda)
    #17 do_simple_func gdb/cli/cli-decode.c:95 (gdb+0x65b078)
    #18 cmd_func(cmd_list_element*, char const*, int) gdb/cli/cli-decode.c:2735 (gdb+0x65ed53)
    #19 execute_command(char const*, int) gdb/top.c:575 (gdb+0xe3a7ea)
    #20 catch_command_errors gdb/main.c:518 (gdb+0xa183fd)
    #21 execute_cmdargs gdb/main.c:617 (gdb+0xa185bf)
    #22 captured_main_1 gdb/main.c:1289 (gdb+0xa1aad8)
    #23 captured_main gdb/main.c:1310 (gdb+0xa1b9da)
    #24 gdb_main(captured_main_args*) gdb/main.c:1339 (gdb+0xa1b9da)
    #25 main gdb/gdb.c:39 (gdb+0x42506a)

  Previous read of size 1 at 0x7b200000410d by thread T2:
    #0 write_gdbindex gdb/dwarf2/index-write.c:1214 (gdb+0x75bb30)
    bminor#1 write_dwarf_index(dwarf2_per_bfd*, char const*, char const*, char const*, dw_index_kind) gdb/dwarf2/index-write.c:1469 (gdb+0x75f803)
    bminor#2 index_cache::store(dwarf2_per_bfd*, index_cache_store_context const&) gdb/dwarf2/index-cache.c:173 (gdb+0x755a36)
    bminor#3 cooked_index::maybe_write_index(dwarf2_per_bfd*, index_cache_store_context const&) gdb/dwarf2/cooked-index.c:642 (gdb+0x71c96d)
    bminor#4 operator() gdb/dwarf2/cooked-index.c:471 (gdb+0x71c96d)
    bminor#5 _M_invoke /usr/include/c++/7/bits/std_function.h:316 (gdb+0x71c96d)
    bminor#6 std::function<void ()>::operator()() const /usr/include/c++/7/bits/std_function.h:706 (gdb+0x72a57c)
    bminor#7 void std::__invoke_impl<void, std::function<void ()>&>(std::__invoke_other, std::function<void ()>&) /usr/include/c++/7/bits/invoke.h:60 (gdb+0x72a5db)
    bminor#8 std::__invoke_result<std::function<void ()>&>::type std::__invoke<std::function<void ()>&>(std::function<void ()>&) /usr/include/c++/7/bits/invoke.h:95 (gdb+0x72a5db)
    bminor#9 std::__future_base::_Task_state<std::function<void ()>, std::allocator<int>, void ()>::_M_run()::{lambda()bminor#1}::operator()() const /usr/include/c++/7/future:1421 (gdb+0x72a5db)
    bminor#10 std::__future_base::_Task_setter<std::unique_ptr<std::__future_base::_Result<void>, std::__future_base::_Result_base::_Deleter>, std::__future_base::_Task_state<std::function<void ()>, std::allocator<int>, void ()>::_M_run()::{lambda()bminor#1}, void>::operator()() const /usr/include/c++/7/future:1362 (gdb+0x72a5db)
    bminor#11 std::_Function_handler<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> (), std::__future_base::_Task_setter<std::unique_ptr<std::__future_base::_Result<void>, std::__future_base::_Result_base::_Deleter>, std::__future_base::_Task_state<std::function<void ()>, std::allocator<int>, void ()>::_M_run()::{lambda()bminor#1}, void> >::_M_invoke(std::_Any_data const&) /usr/include/c++/7/bits/std_function.h:302 (gdb+0x72a5db)
    bminor#12 std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>::operator()() const /usr/include/c++/7/bits/std_function.h:706 (gdb+0x724954)
    #13 std::__future_base::_State_baseV2::_M_do_set(std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*) /usr/include/c++/7/future:561 (gdb+0x724954)
    #14 void std::__invoke_impl<void, void (std::__future_base::_State_baseV2::*)(std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*), std::__future_base::_State_baseV2*, std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*>(std::__invoke_memfun_deref, void (std::__future_base::_State_baseV2::*&&)(std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*), std::__future_base::_State_baseV2*&&, std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*&&, bool*&&) /usr/include/c++/7/bits/invoke.h:73 (gdb+0x72434a)
    #15 std::__invoke_result<void (std::__future_base::_State_baseV2::*)(std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*), std::__future_base::_State_baseV2*, std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*>::type std::__invoke<void (std::__future_base::_State_baseV2::*)(std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*), std::__future_base::_State_baseV2*, std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*>(void (std::__future_base::_State_baseV2::*&&)(std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*), std::__future_base::_State_baseV2*&&, std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*&&, bool*&&) /usr/include/c++/7/bits/invoke.h:95 (gdb+0x72434a)
    #16 std::call_once<void (std::__future_base::_State_baseV2::*)(std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*), std::__future_base::_State_baseV2*, std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*>(std::once_flag&, void (std::__future_base::_State_baseV2::*&&)(std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*), std::__future_base::_State_baseV2*&&, std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*&&, bool*&&)::{lambda()bminor#1}::operator()() const /usr/include/c++/7/mutex:672 (gdb+0x72434a)
    #17 std::call_once<void (std::__future_base::_State_baseV2::*)(std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*), std::__future_base::_State_baseV2*, std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*>(std::once_flag&, void (std::__future_base::_State_baseV2::*&&)(std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*), std::__future_base::_State_baseV2*&&, std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*&&, bool*&&)::{lambda()bminor#2}::operator()() const /usr/include/c++/7/mutex:677 (gdb+0x72434a)
    #18 std::call_once<void (std::__future_base::_State_baseV2::*)(std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*), std::__future_base::_State_baseV2*, std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*>(std::once_flag&, void (std::__future_base::_State_baseV2::*&&)(std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*), std::__future_base::_State_baseV2*&&, std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*&&, bool*&&)::{lambda()bminor#2}::_FUN() /usr/include/c++/7/mutex:677 (gdb+0x72434a)
    #19 pthread_once <null> (libtsan.so.0+0x4457c)
    #20 __gthread_once /usr/include/c++/7/x86_64-suse-linux/bits/gthr-default.h:699 (gdb+0x72532b)
    #21 void std::call_once<void (std::__future_base::_State_baseV2::*)(std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*), std::__future_base::_State_baseV2*, std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*>(std::once_flag&, void (std::__future_base::_State_baseV2::*&&)(std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*), std::__future_base::_State_baseV2*&&, std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*&&, bool*&&) /usr/include/c++/7/mutex:684 (gdb+0x72532b)
    #22 std::__future_base::_State_baseV2::_M_set_result(std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>, bool) /usr/include/c++/7/future:401 (gdb+0x174570d)
    #23 std::__future_base::_Task_state<std::function<void ()>, std::allocator<int>, void ()>::_M_run() /usr/include/c++/7/future:1423 (gdb+0x174570d)
    #24 std::packaged_task<void ()>::operator()() /usr/include/c++/7/future:1556 (gdb+0x174570d)
    #25 gdb::thread_pool::thread_function() gdbsupport/thread-pool.cc:242 (gdb+0x174570d)
    #26 void std::__invoke_impl<void, void (gdb::thread_pool::*)(), gdb::thread_pool*>(std::__invoke_memfun_deref, void (gdb::thread_pool::*&&)(), gdb::thread_pool*&&) /usr/include/c++/7/bits/invoke.h:73 (gdb+0x17480c0)
    #27 std::__invoke_result<void (gdb::thread_pool::*)(), gdb::thread_pool*>::type std::__invoke<void (gdb::thread_pool::*)(), gdb::thread_pool*>(void (gdb::thread_pool::*&&)(), gdb::thread_pool*&&) /usr/include/c++/7/bits/invoke.h:95 (gdb+0x17480c0)
    #28 decltype (__invoke((_S_declval<0ul>)(), (_S_declval<1ul>)())) std::thread::_Invoker<std::tuple<void (gdb::thread_pool::*)(), gdb::thread_pool*> >::_M_invoke<0ul, 1ul>(std::_Index_tuple<0ul, 1ul>) /usr/include/c++/7/thread:234 (gdb+0x17480c0)
    #29 std::thread::_Invoker<std::tuple<void (gdb::thread_pool::*)(), gdb::thread_pool*> >::operator()() /usr/include/c++/7/thread:243 (gdb+0x17480c0)
    #30 std::thread::_State_impl<std::thread::_Invoker<std::tuple<void (gdb::thread_pool::*)(), gdb::thread_pool*> > >::_M_run() /usr/include/c++/7/thread:186 (gdb+0x17480c0)
    #31 <null> <null> (libstdc++.so.6+0xdcac2)
  ...
SUMMARY: ThreadSanitizer: data race gdb/dwarf2/read.c:2033 in dw2_get_file_names_reader
...

The race happens when issuing the "file $exec" command.

The race is between:
- a worker thread writing the index cache, and in the process reading
  dwarf2_per_cu_data::is_debug_type, and
- the main thread writing to dwarf2_per_cu_data::files_read.

The two bitfields dwarf2_per_cu_data::files_read and
dwarf2_per_cu_data::is_debug_type share the same bitfield container.

Fix this by making dwarf2_per_cu_data::files_read a packed<bool, 1>.

Tested on x86_64-linux.

PR symtab/30718
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=30718
mikpe pushed a commit to mikpe/binutils-gdb that referenced this pull request Aug 5, 2023
Expect a `.MIPS.options' section alternatively to `.reginfo' and ignore
contents of either as irrelevant for all the affected compact EH tests,
removing these regressions:

mips64-openbsd  -FAIL: Compact EH EB bminor#1 with personality ID and FDE data
mips64-openbsd  -FAIL: Compact EH EB bminor#2 with personality routine and FDE data
mips64-openbsd  -FAIL: Compact EH EB bminor#3 with personality id and large FDE data
mips64-openbsd  -FAIL: Compact EH EB bminor#4 with personality id, FDE data and LSDA
mips64-openbsd  -FAIL: Compact EH EB bminor#5 with personality routine, FDE data and LSDA
mips64-openbsd  -FAIL: Compact EH EB bminor#6 with personality id, LSDA and large FDE data
mips64-openbsd  -FAIL: Compact EH EL bminor#1 with personality ID and FDE data
mips64-openbsd  -FAIL: Compact EH EL bminor#2 with personality routine and FDE data
mips64-openbsd  -FAIL: Compact EH EL bminor#3 with personality id and large FDE data
mips64-openbsd  -FAIL: Compact EH EL bminor#4 with personality id, FDE data and LSDA
mips64-openbsd  -FAIL: Compact EH EL bminor#5 with personality routine, FDE data and LSDA
mips64-openbsd  -FAIL: Compact EH EL bminor#6 with personality id, LSDA and large FDE data
mips64el-openbsd  -FAIL: Compact EH EB bminor#1 with personality ID and FDE data
mips64el-openbsd  -FAIL: Compact EH EB bminor#2 with personality routine and FDE data
mips64el-openbsd  -FAIL: Compact EH EB bminor#3 with personality id and large FDE data
mips64el-openbsd  -FAIL: Compact EH EB bminor#4 with personality id, FDE data and LSDA
mips64el-openbsd  -FAIL: Compact EH EB bminor#5 with personality routine, FDE data and LSDA
mips64el-openbsd  -FAIL: Compact EH EB bminor#6 with personality id, LSDA and large FDE data
mips64el-openbsd  -FAIL: Compact EH EL bminor#1 with personality ID and FDE data
mips64el-openbsd  -FAIL: Compact EH EL bminor#2 with personality routine and FDE data
mips64el-openbsd  -FAIL: Compact EH EL bminor#3 with personality id and large FDE data
mips64el-openbsd  -FAIL: Compact EH EL bminor#4 with personality id, FDE data and LSDA
mips64el-openbsd  -FAIL: Compact EH EL bminor#5 with personality routine, FDE data and LSDA
mips64el-openbsd  -FAIL: Compact EH EL bminor#6 with personality id, LSDA and large FDE data

Co-Authored-By: Maciej W. Rozycki <macro@orcam.me.uk>

	gas/
	* testsuite/gas/mips/compact-eh-eb-1.d: Accept `.MIPS.options'
	section as an alternative to `.reginfo' and ignore contents of
	either.
	* testsuite/gas/mips/compact-eh-eb-2.d: Likewise.
	* testsuite/gas/mips/compact-eh-eb-3.d: Likewise.
	* testsuite/gas/mips/compact-eh-eb-4.d: Likewise.
	* testsuite/gas/mips/compact-eh-eb-5.d: Likewise.
	* testsuite/gas/mips/compact-eh-eb-6.d: Likewise.
	* testsuite/gas/mips/compact-eh-el-1.d: Likewise.
	* testsuite/gas/mips/compact-eh-el-2.d: Likewise.
	* testsuite/gas/mips/compact-eh-el-3.d: Likewise.
	* testsuite/gas/mips/compact-eh-el-4.d: Likewise.
	* testsuite/gas/mips/compact-eh-el-5.d: Likewise.
	* testsuite/gas/mips/compact-eh-el-6.d: Likewise.

(cherry picked from commit 316be2b)
pietraferreira referenced this pull request in pietraferreira/binutils-gdb Aug 17, 2023
It was pointed out on the mailing list[1] that after this commit:

  commit b1e0126
  Date:   Wed Jun 21 14:18:54 2023 +0100

      gdb: don't resume vfork parent while child is still running

the test gdb.base/vfork-follow-parent.exp now has some failures when
run with the native-gdbserver or native-extended-gdbserver boards:

  FAIL: gdb.base/vfork-follow-parent.exp: resolution_method=schedule-multiple: continue to end of inferior 2 (timeout)
  FAIL: gdb.base/vfork-follow-parent.exp: resolution_method=schedule-multiple: inferior 1 (timeout)
  FAIL: gdb.base/vfork-follow-parent.exp: resolution_method=schedule-multiple: print unblock_parent = 1 (timeout)
  FAIL: gdb.base/vfork-follow-parent.exp: resolution_method=schedule-multiple: continue to break_parent (timeout)

The reason that these failures don't show up when run on the standard
unix board is that the test is only run in the default operating mode,
so for Linux this will be all-stop on top of non-stop.

If we adjust the test script so that it runs in the default mode and
with target-non-stop turned off, then we see the same failures on the
unix board.  This commit includes this change.

The way that the test is written means that it is not (currently)
possible to turn on non-stop mode and have the test still work, so
this commit does not do that.

I have also updated the test script so that the vfork child performs
an exec as well as the current exit.  Exec and exit are the two ways
in which a vfork child can release the vfork parent, so testing both
of these cases is useful I think.

In this test the inferior performs a vfork and the vfork-child
immediately exits.  The vfork-parent will wait for the vfork-child and
then blocks waiting for gdb.  Once gdb has released the vfork-parent,
the vfork-parent also exits.

In the test that fails, GDB sets 'detach-on-fork off' and then runs to
the vfork.  At this point the test tries to just "continue", but this
fails as the vfork-parent is still selected, and the parent can't
continue until the vfork-child completes.  As the vfork-child is
stopped by GDB the parent will never stop once resumed, so GDB refuses
to resume it.

The test script then sets 'schedule-multiple on' and once again
continues.  This time GDB, in theory, resumes both the parent and the
child, the parent will be held blocked by the kernel, but the child
will run until it exits, and which point GDB stops again, this time
with inferior 2, the newly exited vfork-child, selected.

What happens after this in the test script is irrelevant as far as
this failure is concerned.

To understand why the test started failing we should consider the
behaviour of four different cases:

  1. All-stop-on-non-stop before commit b1e0126,

  2. All-stop-on-non-stop after commit b1e0126,

  3. All-stop-on-all-stop before commit b1e0126, and

  4. All-stop-on-all-stop after commit b1e0126.

Only case #4 is failing after commit b1e0126, but I think the
other cases are interesting because, (a) they inform how we might fix
the regression, and (b) it turns out the behaviour of #2 changed too
with the commit, but the change was harmless.

For #1 All-stop-on-non-stop before commit b1e0126, what happens
is:

  1. GDB calls proceed with the vfork-parent selected, as schedule
     multiple is on user_visible_resume_ptid returns -1 (everything)
     as the resume_ptid (see proceed function),

  2. As this is all-stop-on-non-stop, every thread is resumed
    individually, so GDB tries to resume both the vfork-parent and the
    vfork-child, both of which succeed,

  3. The vfork-parent is held stopped by the kernel,

  4. The vfork-child completes (exits) at which point the GDB sees the
     EXITED event for the vfork-child and the VFORK_DONE event for the
     vfork-parent,

  5. At this point we might take two paths depending on which event
     GDB handles first, if GDB handles the VFORK_DONE first then:

     (a) As GDB is controlling both parent and child the VFORK_DONE is
         ignored (see handle_vfork_done), the vfork-parent will be
	 resumed,

     (b) GDB processes the EXITED event, selects the (now defunct)
         vfork-child, and stops, returning control to the user.

     Alternatively, if GDB selects the EXITED event first then:

     (c) GDB processes the EXITED event, selects the (now defunct)
         vfork-child, and stops, returning control to the user.

     (d) At some future time the user resumes the vfork-parent, at
         which point the VFORK_DONE is reported to GDB, however, GDB
	 is ignoring the VFORK_DONE (see handle_vfork_done), so the
	 parent is resumed.

For case #2, all-stop-on-non-stop after commit b1e0126, the
important difference is in step (2) above, now, instead of resuming
both the vfork-parent and the vfork-child, only the vfork-child is
resumed.  As such, when we get to step (5), only a single event, the
EXITED event is reported.

GDB handles the EXITED just as in (5)(c), then, later, when the user
resumes the vfork-parent, the VFORKED_DONE is immediately delivered
from the kernel, but this is ignored just as in (5)(d), and so,
though the pattern of when the vfork-parent is resumed changes, the
overall pattern of which events are reported and when, doesn't
actually change.  In fact, by not resuming the vfork-parent, the order
of events (in this test) is now deterministic, which (maybe?) is a
good thing.

If we now consider case #3, all-stop-on-all-stop before commit
b1e0126, then what happens is:

  1. GDB calls proceed with the vfork-parent selected, as schedule
     multiple is on user_visible_resume_ptid returns -1 (everything)
     as the resume_ptid (see proceed function),

  2. As this is all-stop-on-all-stop, the resume is passed down to the
     linux-nat target, the vfork-parent is the event thread, while the
     vfork-child is a sibling of the event thread,

  3. In linux_nat_target::resume, GDB calls linux_nat_resume_callback
     for all threads, this causes the vfork-child to be resumed.  Then
     in linux_nat_target::resume, the event thread, the vfork-parent,
     is also resumed.

  4. The vfork-parent is held stopped by the kernel,

  5. The vfork-child completes (exits) at which point the GDB sees the
     EXITED event for the vfork-child and the VFORK_DONE event for the
     vfork-parent,

  6. We are now in a situation identical to step (5) as for
     all-stop-on-non-stop above, GDB selects one of the events to
     handle, and whichever we select the user sees the correct
     behaviour.

And so, finally, we can consider #4, all-stop-on-all-stop after commit
b1e0126, this is the case that started failing.

We start out just like above, in proceed, the resume_ptid is
-1 (resume everything), due to schedule multiple being on.  And just
like above, due to the target being all-stop, we call
proceed_resume_thread_checked just once, for the current thread,
which, remember, is the vfork-parent thread.

The change in commit b1e0126 was to avoid resuming a vfork-parent
thread, read the commit message for the justification for this change.

However, this means that GDB now rejects resuming the vfork-parent in
this case, which means that nothing gets resumed!  Obviously, if
nothing resumes, then nothing will ever stop, and so GDB appears to
hang.

I considered a couple of solutions which, in the end, I didn't go
with, these were:

  1. Move the vfork-parent check out of proceed_resume_thread_checked,
     and place it in proceed, but only on the all-stop-on-non-stop
     path, this should still address the issue seen in b1e0126,
     but would avoid the issue seen here.  I rejected this just
     because it didn't feel great to split the checks that exist in
     proceed_resume_thread_checked like this,

  2. Extend the condition in proceed_resume_thread_checked by adding a
     target_is_non_stop_p check.  This would have the same effect as
     idea 1, but leaves all the checks in the same place, which I
     think would be better, but this still just didn't feel right to
     me, and so,

What I noticed was that for the all-stop-on-non-stop, after commit
b1e0126, we only resumed the vfork-child, and this seems fine.
The vfork-parent isn't going to run anyway (the kernel will hold it
back), so if feels like we there's no harm in just waiting for the
child to complete, and then resuming the parent.

So then I started looking at follow_fork, which is called from the top
of proceed.  This function already has the task of switching between
the parent and child based on which the user wishes to follow.  So, I
wondered, could we use this to switch to the vfork-child in the case
that we are attached to both?

Turns out this is pretty simple to do.

Having done that, now the process is for all-stop-on-all-stop after
commit b1e0126, and with this new fix is:

  1. GDB calls proceed with the vfork-parent selected, but,

  2. In follow_fork, and follow_fork_inferior, GDB switches the
     selected thread to be that of the vfork-child,

  3. Back in proceed user_visible_resume_ptid returns -1 (everything)
     as the resume_ptid still, but now,

  4. When GDB calls proceed_resume_thread_checked, the vfork-child is
     the current selected thread, this is not a vfork-parent, and so
     GDB allows the proceed to continue to the linux-nat target,

  5. In linux_nat_target::resume, GDB calls linux_nat_resume_callback
     for all threads, this does not resume the vfork-parent (because
     it is a vfork-parent), and then the vfork-child is resumed as
     this is the event thread,

At this point we are back in the same situation as for
all-stop-on-non-stop after commit b1e0126, that is, the
vfork-child is resumed, while the vfork-parent is held stopped by
GDB.

Eventually the vfork-child will exit or exec, at which point the
vfork-parent will be resumed.

[1] https://inbox.sourceware.org/gdb-patches/3e1e1db0-13d9-dd32-b4bb-051149ae6e76@simark.ca/
berenm pushed a commit that referenced this pull request Aug 26, 2023
After running a number of programs under Windows gdb and detaching
them, I typed run in gdb, and got a hang, here:

 (top-gdb) bt
 #0  sharing_input_terminal (pid=4672) at /home/pedro/gdb/src/gdb/mingw-hdep.c:388
 #1  0x00007ff71a2d8678 in sharing_input_terminal (inf=0x23bf23dafb0) at /home/pedro/gdb/src/gdb/inflow.c:269
 #2  0x00007ff71a2d887b in child_terminal_save_inferior (self=0x23bf23de060) at /home/pedro/gdb/src/gdb/inflow.c:423
 #3  0x00007ff71a2c80c0 in inf_child_target::terminal_save_inferior (this=0x23bf23de060) at /home/pedro/gdb/src/gdb/inf-child.c:111
 #4  0x00007ff71a429c0f in target_terminal_is_ours_kind (desired_state=target_terminal_state::is_ours_for_output) at /home/pedro/gdb/src/gdb/target.c:1037
 #5  0x00007ff71a429e02 in target_terminal::ours_for_output () at /home/pedro/gdb/src/gdb/target.c:1094
 #6  0x00007ff71a2ccc8e in post_create_inferior (from_tty=0) at /home/pedro/gdb/src/gdb/infcmd.c:245
 #7  0x00007ff71a2cd431 in run_command_1 (args=0x0, from_tty=0, run_how=RUN_NORMAL) at /home/pedro/gdb/src/gdb/infcmd.c:502
 #8  0x00007ff71a2cd58b in run_command (args=0x0, from_tty=0) at /home/pedro/gdb/src/gdb/infcmd.c:527

The problem is that the loop around GetConsoleProcessList looped
forever, because there were exactly 10 processes to return.
GetConsoleProcessList's documentation says:

  If the buffer is too small to hold all the valid process identifiers,
  the return value is the required number of array elements. The
  function will have stored no identifiers in the buffer. In this
  situation, use the return value to allocate a buffer that is large
  enough to store the entire list and call the function again.

In this case, the buffer wasn't too small, it was exactly the right
size, so we should have broken out of the loop.  We didn't due to a
"<" check that should have been "<=".  That is fixed by this patch.

Approved-By: Tom Tromey <tom@tromey.com>
Reviewed-By: Eli Zaretskii <eliz@gnu.org>
Change-Id: I14e4909f2ac2fa83d0d9b6e64418b5831ac4e4e3
berenm pushed a commit that referenced this pull request Sep 29, 2023
This commit fixes an issue that was discovered while writing the tests
for the previous commit.

I noticed that, when GDB restarts an inferior, the executable_changed
event would trigger twice.  The first notification would originate
from:

  #0  exec_file_attach (filename=0x4046680 "/tmp/hello.x", from_tty=0) at ../../src/gdb/exec.c:513
  #1  0x00000000006f3adb in reopen_exec_file () at ../../src/gdb/corefile.c:122
  #2  0x0000000000e6a3f2 in generic_mourn_inferior () at ../../src/gdb/target.c:3682
  #3  0x0000000000995121 in inf_child_target::mourn_inferior (this=0x2fe95c0 <the_amd64_linux_nat_target>) at ../../src/gdb/inf-child.c:192
  #4  0x0000000000995cff in inf_ptrace_target::mourn_inferior (this=0x2fe95c0 <the_amd64_linux_nat_target>) at ../../src/gdb/inf-ptrace.c:125
  #5  0x0000000000a32472 in linux_nat_target::mourn_inferior (this=0x2fe95c0 <the_amd64_linux_nat_target>) at ../../src/gdb/linux-nat.c:3609
  #6  0x0000000000e68a40 in target_mourn_inferior (ptid=...) at ../../src/gdb/target.c:2761
  #7  0x0000000000a323ec in linux_nat_target::kill (this=0x2fe95c0 <the_amd64_linux_nat_target>) at ../../src/gdb/linux-nat.c:3593
  #8  0x0000000000e64d1c in target_kill () at ../../src/gdb/target.c:924
  #9  0x00000000009a19bc in kill_if_already_running (from_tty=1) at ../../src/gdb/infcmd.c:328
  #10 0x00000000009a1a6f in run_command_1 (args=0x0, from_tty=1, run_how=RUN_STOP_AT_MAIN) at ../../src/gdb/infcmd.c:381
  #11 0x00000000009a20a5 in start_command (args=0x0, from_tty=1) at ../../src/gdb/infcmd.c:527
  #12 0x000000000068dc5d in do_simple_func (args=0x0, from_tty=1, c=0x35c7200) at ../../src/gdb/cli/cli-decode.c:95

While the second originates from:

  #0  exec_file_attach (filename=0x3d7a1d0 "/tmp/hello.x", from_tty=0) at ../../src/gdb/exec.c:513
  #1  0x0000000000dfe525 in reread_symbols (from_tty=1) at ../../src/gdb/symfile.c:2517
  #2  0x00000000009a1a98 in run_command_1 (args=0x0, from_tty=1, run_how=RUN_STOP_AT_MAIN) at ../../src/gdb/infcmd.c:398
  #3  0x00000000009a20a5 in start_command (args=0x0, from_tty=1) at ../../src/gdb/infcmd.c:527
  #4  0x000000000068dc5d in do_simple_func (args=0x0, from_tty=1, c=0x35c7200) at ../../src/gdb/cli/cli-decode.c:95

In the first case the call to exec_file_attach first passes through
reopen_exec_file.  The reopen_exec_file performs a modification time
check on the executable file, and only calls exec_file_attach if the
executable has changed on disk since it was last loaded.

However, in the second case things work a little differently.  In this
case GDB is really trying to reread the debug symbol.  As such, we
iterate over the objfiles list, and for each of those we check the
modification time, if the file on disk has changed then we reload the
debug symbols from that file.

However, there is an additional check, if the objfile has the same
name as the executable then we will call exec_file_attach, but we do
so without checking the cached modification time that indicates when
the executable was last reloaded, as a result, we reload the
executable twice.

In this commit I propose that reread_symbols be changed to
unconditionally call reopen_exec_file before performing the objfile
iteration.  This will ensure that, if the executable has changed, then
the executable will be reloaded, however, if the executable has
already been recently reloaded, we will not reload it for a second
time.

After handling the executable, GDB can then iterate over the objfiles
list and reload them in the normal way.

With this done I now see the executable reloaded only once when GDB
restarts an inferior, which means I can remove the kfail that I added
to the gdb.python/py-exec-file.exp test in the previous commit.

Approved-By: Tom Tromey <tom@tromey.com>
berenm pushed a commit that referenced this pull request Oct 6, 2023
It was pointed out on the mailing list that a recently added
test (gdb.python/py-progspace-events.exp) was failing when run with
the native-extended-gdbserver board.  This test was added with this
commit:

  commit 59912fb
  Date:   Tue Sep 19 11:45:36 2023 +0100

      gdb: add Python events for program space addition and removal

It turns out though that the test is failing due to a existing bug
in GDB, the new test just exposes the problem.  Additionally, the
failure really doesn't even rely on the new functionality added in the
above commit.  I reduced the test to a simple set of steps that
reproduced the failure and tested against GDB 13, and the test passes;
so the bug was introduced since then.  In fact, the bug was introduced
with this commit:

  commit a282736
  Date:   Fri Sep 8 15:48:16 2023 +0100

      gdb: remove final user of the executable_changed observer

This commit changed how the per-inferior auxv data cache is managed,
specifically, when the cache is cleared, and it is this that leads to
the failure.

This bug is interesting because it exposes a number of issues with
GDB, I'll explain all of the problems I see, though ultimately, I only
propose fixing one problem in this commit, which is enough to resolve
the crash we are currently seeing.

The crash that we are seeing manifests like this:

  ...
  [Inferior 2 (process 3970384) exited normally]
  +inferior 1
  [Switching to inferior 1 [process 3970383] (/tmp/build/gdb/testsuite/outputs/gdb.python/py-progspace-events/py-progspace-events)]
  [Switching to thread 1.1 (Thread 3970383.3970383)]
  #0  breakpt () at /tmp/build/gdb/testsuite/../../../src/gdb/testsuite/gdb.python/py-progspace-events.c:28
  28	{ /* Nothing.  */ }
  (gdb) step
  +step
  terminate called after throwing an instance of 'gdb_exception_error'

  Fatal signal: Aborted
  ... etc ...

What's happening is that GDB attempts to refill the auxv cache as a
result of the gdbarch_has_shared_address_space call in
program_space::~program_space, the backtrace looks like this:

  #0  0x00007fb4f419a9a5 in raise () from /lib64/libpthread.so.0
  #1  0x00000000008b635d in handle_fatal_signal (sig=6) at ../../src/gdb/event-top.c:912
  #2  <signal handler called>
  #3  0x00007fb4f38e3625 in raise () from /lib64/libc.so.6
  #4  0x00007fb4f38cc8d9 in abort () from /lib64/libc.so.6
  #5  0x00007fb4f3c70756 in __gnu_cxx::__verbose_terminate_handler() [clone .cold] () from /lib64/libstdc++.so.6
  #6  0x00007fb4f3c7c6dc in __cxxabiv1::__terminate(void (*)()) () from /lib64/libstdc++.so.6
  #7  0x00007fb4f3c7b6e9 in __cxa_call_terminate () from /lib64/libstdc++.so.6
  #8  0x00007fb4f3c7c094 in __gxx_personality_v0 () from /lib64/libstdc++.so.6
  #9  0x00007fb4f3a80c63 in _Unwind_RaiseException_Phase2 () from /lib64/libgcc_s.so.1
  #10 0x00007fb4f3a8154e in _Unwind_Resume () from /lib64/libgcc_s.so.1
  #11 0x0000000000e8832d in target_read_alloc_1<unsigned char> (ops=0x408a3a0, object=TARGET_OBJECT_AUXV, annex=0x0) at ../../src/gdb/target.c:2266
  #12 0x0000000000e73dea in target_read_alloc (ops=0x408a3a0, object=TARGET_OBJECT_AUXV, annex=0x0) at ../../src/gdb/target.c:2315
  #13 0x000000000058248c in target_read_auxv_raw (ops=0x408a3a0) at ../../src/gdb/auxv.c:379
  #14 0x000000000058243d in target_read_auxv () at ../../src/gdb/auxv.c:368
  #15 0x000000000058255c in target_auxv_search (match=0x0, valp=0x7ffdee17c598) at ../../src/gdb/auxv.c:415
  #16 0x0000000000a464bb in linux_is_uclinux () at ../../src/gdb/linux-tdep.c:433
  #17 0x0000000000a464f6 in linux_has_shared_address_space (gdbarch=0x409a2d0) at ../../src/gdb/linux-tdep.c:440
  #18 0x0000000000510eae in gdbarch_has_shared_address_space (gdbarch=0x409a2d0) at ../../src/gdb/gdbarch.c:4889
  #19 0x0000000000bc7558 in program_space::~program_space (this=0x4544aa0, __in_chrg=<optimized out>) at ../../src/gdb/progspace.c:124
  #20 0x00000000009b245d in delete_inferior (inf=0x47b3de0) at ../../src/gdb/inferior.c:290
  #21 0x00000000009b2c10 in prune_inferiors () at ../../src/gdb/inferior.c:480
  #22 0x00000000009c5e3e in fetch_inferior_event () at ../../src/gdb/infrun.c:4558
  #23 0x000000000099b4dc in inferior_event_handler (event_type=INF_REG_EVENT) at ../../src/gdb/inf-loop.c:42
  #24 0x0000000000cbc64f in remote_async_serial_handler (scb=0x4090a30, context=0x408a6b0) at ../../src/gdb/remote.c:14859
  #25 0x0000000000d83d3a in run_async_handler_and_reschedule (scb=0x4090a30) at ../../src/gdb/ser-base.c:138
  #26 0x0000000000d83e1f in fd_event (error=0, context=0x4090a30) at ../../src/gdb/ser-base.c:189

So this is problem #1, if we throw an exception while deleting a
program_space then this is not caught, and is going to crash GDB.

Problem #2 becomes evident when we ask why GDB is throwing an error in
this case; the error is thrown because the remote target, operating in
non-async mode, can't read the auxv data while an inferior is running
and GDB is waiting for a stop reply.  The problem here then, is why
does GDB get into a position where it tries to interact with the
remote target in this way, at this time?  The problem is caused by the
prune_inferiors call which can be seen in the above backtrace.

In prune_inferiors we check if the inferior is deletable, and if it
is, we delete it.  The problem is, I think, we should also check if
the target is currently in a state that would allow us to delete the
inferior.  We don't currently have such a check available, we'd need
to add one, but for the remote target, this would return false if the
remote is in async mode and the remote is currently waiting for a stop
reply.  With this change in place GDB would defer deleting the
inferior until the remote target has stopped, at which point GDB would
be able to refill the auxv cache successfully.

And then, problem #3 becomes evident when we ask why GDB is needing to
refill the auxv cache now when it didn't need to for GDB 13.  This is
where the second commit mentioned above (a282736) comes in.
Prior to this commit, the auxv cache was cleared by the
executable_changed observer, while after that commit the auxv cache
was cleared by the new_objfile observer -- but only when the
new_objfile observer is used in the special mode that actually means
that all objfiles have been unloaded (I know, the overloading of the
new_objfile observer is horrible, and unnecessary, but it's not really
important for this bug).

The difference arises because the new_objfile observer is triggered
from clear_symtab_users, which in turn is called from
program_space::~program_space.  The new_objfile observer for auxv does
this:

  static void
  auxv_new_objfile_observer (struct objfile *objfile)
  {
    if (objfile == nullptr)
      invalidate_auxv_cache_inf (current_inferior ());
  }

That is, when all the objfiles are unloaded, we clear the auxv cache
for the current inferior.

The problem is, then when we look at the prune_inferiors ->
delete_inferior -> ~program_space path, we see that the current
inferior is not going to be an inferior that exists within the
program_space being deleted; delete_inferior removes the deleted
inferior from the global inferior list, and then only deletes the
program_space if program_space::empty() returns true, which is only
the case if the current inferior isn't within the program_space to
delete, and no other inferior exists within that program_space
either.

What this means is that when the new_objfile observer is called we
can't rely on the current inferior having any relationship with the
program space in which the objfiles were removed.  This was an error
in the commit a282736, the only thing we can rely on is the
current program space.  As a result of this mistake, after commit
a282736, GDB was sometimes clearing the auxv cache for a random
inferior.  In the native target case this was harmless as we can
always refill the cache when needed, but in the remote target case, if
we need to refill the cache when the remote target is executing, then
we get the crash we observed.

And additionally, if we think about this a little more, we see that
commit a282736 made another mistake.  When all the objfiles are
removed, they are removed from a program_space, a program_space might
contain multiple inferiors, so surely, we should clear the auxv cache
for all of the matching inferiors?

Given these two insights, that the current_inferior is not relevant,
only the current_program_space, and that we should be clearing the
cache for all inferiors in the current_program_space, we can update
auxv_new_objfile_observer to:

  if (objfile == nullptr)
    {
      for (inferior *inf : all_inferiors ())
	{
	  if (inf->pspace == current_program_space)
	    invalidate_auxv_cache_inf (inf);
	}
    }

With this change we now correctly clear the auxv cache for the correct
inferiors, and GDB no longer needs to refill the cache at an
inconvenient time, this avoids the crash we were seeing.

And finally, we reach problem #4.  Inspired by the observation that
using the current_inferior from within the ~program_space function was
not correct, I added some debug to see if current_inferior() was
called anywhere else (below ~program_space), and the answer is yes,
it's called a often.  Mostly the culprit is GDB doing:

  current_inferior ()->top_target ()-> ....

But I think all of these calls are most likely doing the wrong thing,
and only work because the top target in all these cases is shared
between all inferiors, e.g. it's the native target, or the remote
target for all inferiors.  But if we had a truly multi-connection
setup, then we might start to see odd behaviour.

Problem #1 I'm just ignoring for now, I guess at some point we might
run into this again, and then we'd need to solve this.  But in this
case I wasn't sure what a "good" solution would look like.  We need
the auxv data in order to implement the linux_is_uclinux() function.
If we can't get the auxv data then what should we do, assume yes, or
assume no?  The right answer would probably be to propagate the error
back up the stack, but then we reach ~program_space, and throwing
exceptions from a destructor is problematic, so we'd need to catch and
deal at this point.  The linux_is_uclinux() call is made from within
gdbarch_has_shared_address_space(), which is used like:

  if (!gdbarch_has_shared_address_space (target_gdbarch ()))
    delete this->aspace;

So, we would have to choose; delete the address space or not.  If we
delete it on error, then we might delete an address space that is
shared within another program space.  If we don't delete the address
space, then we might leak it.  Neither choice is great.

A better solution might be to have the address spaces be reference
counted, then we could remove the gdbarch_has_shared_address_space
call completely, and just rely on the reference count to auto-delete
the address space when appropriate.

The solution for problem #2 I already hinted at above, we should have
a new target_can_delete_inferiors() call, which should be called from
prune_inferiors, this would prevent GDB from trying to delete
inferiors when a (remote) target is in a state where we know it can't
delete the inferior.  Deleting an inferior often (always?) requires
sending packets to the remote, and if the remote is waiting for a stop
reply then this will never work, so the pruning should be deferred in
this case.

The solution for problem #3 is included in this commit.

And, for problem #4, I'm not sure what the right solution is.  Maybe
delete_inferior should ensure the inferior to be deleted is in place
when ~program_space is called?  But that seems a little weird, as the
current inferior would, in theory, still be using the current
program_space...

Anyway, after this commit, the gdb.python/py-progspace-events.exp test
now passes when run with the native-extended-remote board.

Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=30935
Approved-By: Simon Marchi <simon.marchi@efficios.com>
Change-Id: I41f0e6e2d7ecc1e5e55ec170f37acd4052f46eaf
berenm pushed a commit that referenced this pull request Nov 14, 2023
I noticed that on an Ubuntu 20.04 system, after a following patch
("Step over clone syscall w/ breakpoint,
TARGET_WAITKIND_THREAD_CLONED"), the gdb.threads/step-over-exec.exp
was passing cleanly, but still, we'd end up with four new unexpected
GDB core dumps:

		 === gdb Summary ===

 # of unexpected core files      4
 # of expected passes            48

That said patch is making the pre-existing
gdb.threads/step-over-exec.exp testcase (almost silently) expose a
latent problem in gdb/linux-nat.c, resulting in a GDB crash when:

 #1 - a non-leader thread execs
 #2 - the post-exec program stops somewhere
 #3 - you kill the inferior

Instead of #3 directly, the testcase just returns, which ends up in
gdb_exit, tearing down GDB, which kills the inferior, and is thus
equivalent to #3 above.

Vis (after said patch is applied):

 $ gdb --args ./gdb /home/pedro/gdb/build/gdb/testsuite/outputs/gdb.threads/step-over-exec/step-over-exec-execr-thread-other-diff-text-segs-true
 ...
 (top-gdb) r
 ...
 (gdb) b main
 ...
 (gdb) r
 ...
 Breakpoint 1, main (argc=1, argv=0x7fffffffdb88) at /home/pedro/gdb/build/gdb/testsuite/../../../src/gdb/testsuite/gdb.threads/step-over-exec.c:69
 69        argv0 = argv[0];
 (gdb) c
 Continuing.
 [New Thread 0x7ffff7d89700 (LWP 2506975)]
 Other going in exec.
 Exec-ing /home/pedro/gdb/build/gdb/testsuite/outputs/gdb.threads/step-over-exec/step-over-exec-execr-thread-other-diff-text-segs-true-execd
 process 2506769 is executing new program: /home/pedro/gdb/build/gdb/testsuite/outputs/gdb.threads/step-over-exec/step-over-exec-execr-thread-other-diff-text-segs-true-execd

 Thread 1 "step-over-exec-" hit Breakpoint 1, main () at /home/pedro/gdb/build/gdb/testsuite/../../../src/gdb/testsuite/gdb.threads/step-over-exec-execd.c:28
 28        foo ();
 (gdb) k
 ...
 Thread 1 "gdb" received signal SIGSEGV, Segmentation fault.
 0x000055555574444c in thread_info::has_pending_waitstatus (this=0x0) at ../../src/gdb/gdbthread.h:393
 393         return m_suspend.waitstatus_pending_p;
 (top-gdb) bt
 #0  0x000055555574444c in thread_info::has_pending_waitstatus (this=0x0) at ../../src/gdb/gdbthread.h:393
 #1  0x0000555555a884d1 in get_pending_child_status (lp=0x5555579b8230, ws=0x7fffffffd130) at ../../src/gdb/linux-nat.c:1345
 #2  0x0000555555a8e5e6 in kill_unfollowed_child_callback (lp=0x5555579b8230) at ../../src/gdb/linux-nat.c:3564
 #3  0x0000555555a92a26 in gdb::function_view<int (lwp_info*)>::bind<int, lwp_info*>(int (*)(lwp_info*))::{lambda(gdb::fv_detail::erased_callable, lwp_info*)#1}::operator()(gdb::fv_detail::erased_callable, lwp_info*) const (this=0x0, ecall=..., args#0=0x5555579b8230) at ../../src/gdb/../gdbsupport/function-view.h:284
 #4  0x0000555555a92a51 in gdb::function_view<int (lwp_info*)>::bind<int, lwp_info*>(int (*)(lwp_info*))::{lambda(gdb::fv_detail::erased_callable, lwp_info*)#1}::_FUN(gdb::fv_detail::erased_callable, lwp_info*) () at ../../src/gdb/../gdbsupport/function-view.h:278
 #5  0x0000555555a91f84 in gdb::function_view<int (lwp_info*)>::operator()(lwp_info*) const (this=0x7fffffffd210, args#0=0x5555579b8230) at ../../src/gdb/../gdbsupport/function-view.h:247
 #6  0x0000555555a87072 in iterate_over_lwps(ptid_t, gdb::function_view<int (lwp_info*)>) (filter=..., callback=...) at ../../src/gdb/linux-nat.c:864
 #7  0x0000555555a8e732 in linux_nat_target::kill (this=0x55555653af40 <the_amd64_linux_nat_target>) at ../../src/gdb/linux-nat.c:3590
 #8  0x0000555555cfdc11 in target_kill () at ../../src/gdb/target.c:911
 ...

The root of the problem is that when a non-leader LWP execs, it just
changes its tid to the tgid, replacing the pre-exec leader thread,
becoming the new leader.  There's no thread exit event for the execing
thread.  It's as if the old pre-exec LWP vanishes without trace.  The
ptrace man page says:

 "PTRACE_O_TRACEEXEC (since Linux 2.5.46)
	Stop the tracee at the next execve(2).  A waitpid(2) by the
	tracer will return a status value such that

	  status>>8 == (SIGTRAP | (PTRACE_EVENT_EXEC<<8))

	If the execing thread is not a thread group leader, the thread
	ID is reset to thread group leader's ID before this stop.
	Since Linux 3.0, the former thread ID can be retrieved with
	PTRACE_GETEVENTMSG."

When the core of GDB processes an exec events, it deletes all the
threads of the inferior.  But, that is too late -- deleting the thread
does not delete the corresponding LWP, so we end leaving the pre-exec
non-leader LWP stale in the LWP list.  That's what leads to the crash
above -- linux_nat_target::kill iterates over all LWPs, and after the
patch in question, that code will look for the corresponding
thread_info for each LWP.  For the pre-exec non-leader LWP still
listed, won't find one.

This patch fixes it, by deleting the pre-exec non-leader LWP (and
thread) from the LWP/thread lists as soon as we get an exec event out
of ptrace.

GDBserver does not need an equivalent fix, because it is already doing
this, as side effect of mourning the pre-exec process, in
gdbserver/linux-low.cc:

  else if (event == PTRACE_EVENT_EXEC && cs.report_exec_events)
    {
...
      /* Delete the execing process and all its threads.  */
      mourn (proc);
      switch_to_thread (nullptr);


The crash with gdb.threads/step-over-exec.exp is not observable on
newer systems, which postdate the glibc change to move "libpthread.so"
internals to "libc.so.6", because right after the exec, GDB traps a
load event for "libc.so.6", which leads to GDB trying to open
libthread_db for the post-exec inferior, and, on such systems that
succeeds.  When we load libthread_db, we call
linux_stop_and_wait_all_lwps, which, as the name suggests, stops all
lwps, and then waits to see their stops.  While doing this, GDB
detects that the pre-exec stale LWP is gone, and deletes it.

If we use "catch exec" to stop right at the exec before the
"libc.so.6" load event ever happens, and issue "kill" right there,
then GDB crashes on newer systems as well.  So instead of tweaking
gdb.threads/step-over-exec.exp to cover the fix, add a new
gdb.threads/threads-after-exec.exp testcase that uses "catch exec".
The test also uses the new "maint info linux-lwps" command if testing
on Linux native, which also exposes the stale LWP problem with an
unfixed GDB.

Also tweak a comment in infrun.c:follow_exec referring to how
linux-nat.c used to behave, as it would become stale otherwise.

Reviewed-By: Andrew Burgess <aburgess@redhat.com>
Change-Id: I21ec18072c7750f3a972160ae6b9e46590376643
berenm pushed a commit that referenced this pull request Nov 14, 2023
Running the
gdb.threads/step-over-thread-exit-while-stop-all-threads.exp testcase
added later in the series against gdbserver, after the
TARGET_WAITKIND_NO_RESUMED fix from the following patch, would run
into an infinite loop in stop_all_threads, leading to a timeout:

  FAIL: gdb.threads/step-over-thread-exit-while-stop-all-threads.exp: displaced-stepping=off: target-non-stop=on: iter 0: continue (timeout)

The is really a latent bug, and it is about the fact that
stop_all_threads stops listening to events from a target as soon as it
sees a TARGET_WAITKIND_NO_RESUMED, ignoring that
TARGET_WAITKIND_NO_RESUMED may be delayed.  handle_no_resumed knows
how to handle delayed no-resumed events, but stop_all_threads was
never taught to.

In more detail, here's what happens with that testcase:

#1 - Multiple threads report breakpoint hits to gdb.

#2 - gdb picks one events, and it's for thread 1.  All other stops are
     left pending.  thread 1 needs to move past a breakpoint, so gdb
     stops all threads to start an inline step over for thread 1.
     While stopping threads, some of the threads that were still
     running report events that are also left pending.

#2 - gdb steps thread 1

#3 - Thread 1 exits while stepping (it steps over an exit syscall),
     gdbserver reports thread exit for thread 1

#4 - Thread 1 was the last resumed thread, so gdbserver also reports
     no-resumed:

    [remote]   Notification received: Stop:w0;p3445d0.3445d3
    [remote] Sending packet: $vStopped#55
    [remote] Packet received: N
    [remote] Sending packet: $vStopped#55
    [remote] Packet received: OK

#5 - gdb processes the thread exit for thread 1, finishes the step
     over and restarts threads.

#6 - gdb picks the next event to process out of one of the resumed
     threads with pending events:

    [infrun] random_resumed_with_pending_wait_status: Found 32 events, selecting #11

#7 - This is again a breakpoint hit and the breakpoint needs to be
     stepped over too, so gdb starts a step-over dance again.

#8 - We reach stop_all_threads, which finds that some threads need to
     be stopped.

#9 - wait_one finally consumes the no-resumed event queue by #4.
     Seeing this, wait_one disable target async, to stop listening for
     events out of the remote target.

#10 - We still haven't seen all the stops expected, so
      stop_all_threads tries another iteration.

#11 - Because the remote target is no longer async, and there are no
      other targets, wait_one return no-resumed immediately without
      polling the remote target.

#12 - We still haven't seen all the stops expected, so
      stop_all_threads tries another iteration.  goto #11, looping
      forever.

Fix this by explicitly enabling/re-enabling target async on targets
that can async, before waiting for stops.

Reviewed-By: Andrew Burgess <aburgess@redhat.com>
Change-Id: Ie3ffb0df89635585a6631aa842689cecc989e33f
berenm pushed a commit that referenced this pull request Jan 11, 2024
On aarch64-linux, with gcc 13.2.1, I run into:
...
 (gdb) backtrace^M
 #0  break_here () at solib-search.c:30^M
 #1  0x0000fffff7f20194 in lib2_func4 () at solib-search-lib2.c:50^M
 #2  0x0000fffff7f70194 in lib1_func3 () at solib-search-lib1.c:50^M
 #3  0x0000fffff7f20174 in lib2_func2 () at solib-search-lib2.c:30^M
 #4  0x0000fffff7f70174 in lib1_func1 () at solib-search-lib1.c:30^M
 #5  0x00000000004101b4 in main () at solib-search.c:23^M
 (gdb) PASS: gdb.base/solib-search.exp: \
   backtrace (with wrong libs) (data collection)
 FAIL: gdb.base/solib-search.exp: backtrace (with wrong libs)
...

The FAIL is generated by this code in the test-case:
...
    if { $expect_fail } {
	# If the backtrace output is correct the test isn't sufficiently
	# testing what it should.
	if { $count == $total_expected } {
	    set fail 1
	}
...

The test-case:
- builds two versions of two shared libs, a "right" and "wrong" version, the
  difference being an additional dummy function (called spacer function),
- uses the "right" version to generate a core file,
- uses the "wrong" version to interpret the core file, and
- generates a backtrace.

The intent is that the backtrace is incorrect due to using the "wrong"
version, but actually it's correct.  This is because the spacer functions
aren't large enough.

Fix this by increasing the size of the spacer functions by adding a dummy
loop, after which we have, as expected, an incorrect backtrace:
...
 (gdb) backtrace^M
 #0  break_here () at solib-search.c:30^M
 #1  0x0000fffff7f201c0 in ?? ()^M
 #2  0x0000fffff7f20174 in lib2_func2 () at solib-search-lib2.c:30^M
 #3  0x0000fffff7f20174 in lib2_func2 () at solib-search-lib2.c:30^M
 #4  0x0000fffff7f70174 in lib1_func1 () at solib-search-lib1.c:30^M
 #5  0x00000000004101b4 in main () at solib-search.c:23^M
 (gdb) PASS: gdb.base/solib-search.exp: \
   backtrace (with wrong libs) (data collection)
 PASS: gdb.base/solib-search.exp: backtrace (with wrong libs)
...

Tested on aarch64-linux.
davine47 pushed a commit to davine47/binutils-gdb that referenced this pull request Jan 18, 2024
Along with the relevant unit tests and updates to the existing
regression tests, this adds support for the following novel rcpc3
insns:

  LDIAPP <Wt1>, <Wt2>, [<Xn|SP>]
  LDIAPP <Wt1>, <Wt2>, [<Xn|SP>], bminor#8
  LDIAPP <Xt1>, <Xt2>, [<Xn|SP>]
  LDIAPP <Xt1>, <Xt2>, [<Xn|SP>], #16

  STILP <Wt1>, <Wt2>, [<Xn|SP>]
  STILP <Wt1>, <Wt2>, [<Xn|SP>, #-8]!
  STILP <Xt1>, <Xt2>, [<Xn|SP>]
  STILP <Xt1>, <Xt2>, [<Xn|SP>, #-16]!

  LDAPR <Wt>, [<Xn|SP>], bminor#4
  LDAPR <Xt>, [<Xn|SP>], bminor#8

  STLR <Wt>, [<Xn|SP>, #-4]!
  STLR <Xt>, [<Xn|SP>, #-8]!
berenm pushed a commit that referenced this pull request Feb 3, 2024
Bug PR gdb/28313 describes attaching to a process when the executable
has been deleted.  The bug is for S390 and describes how a user sees a
message 'PC not saved'.

On x86-64 (GNU/Linux) I don't see a 'PC not saved' message, but
instead I see this:

  (gdb) attach 901877
  Attaching to process 901877
  No executable file now.
  warning: Could not load vsyscall page because no executable was specified
  0x00007fa9d9c121e7 in ?? ()
  (gdb) bt
  #0  0x00007fa9d9c121e7 in ?? ()
  #1  0x00007fa9d9c1211e in ?? ()
  #2  0x0000000000000007 in ?? ()
  #3  0x000000002dc8b18d in ?? ()
  #4  0x0000000000000000 in ?? ()
  (gdb)

Notice that the addresses in the backtrace don't seem right, quickly
heading to 0x7 and finally ending at 0x0.

What's going on, in both the s390 case and the x86-64 case is that the
architecture's prologue scanner is going wrong and causing the stack
unwinding to fail.

The prologue scanner goes wrong because GDB has no unwind information.

And GDB has no unwind information because, of course, the executable
has been deleted.

Notice in the example session above we get this line in the output:

  No executable file now.

which indicates that GDB failed to find an executable to debug.

For GNU/Linux when GDB tries to find an executable for a given pid we
end up calling linux_proc_pid_to_exec_file in gdb/nat/linux-procfs.c.
Within this function we call `readlink` on /proc/PID/exe to find the
path of the actual executable.

If the `readlink` call fails then we already fallback on using
/proc/PID/exe as the path to the executable to debug.

However, when the executable has been deleted the `readlink` call
doesn't fail, but the path that is returned points to a non-existent
file.

I propose that we add an `access` call to linux_proc_pid_to_exec_file
to check that the target file exists and can be read.  If the target
can't be read then we should fall back to /proc/PID/exe (assuming that
/proc/PID/exe can be read).

Now on x86-64 the output looks like this:

  (gdb) attach 901877
  Attaching to process 901877
  Reading symbols from /proc/901877/exe...
  Reading symbols from /lib64/libc.so.6...
  (No debugging symbols found in /lib64/libc.so.6)
  Reading symbols from /lib64/ld-linux-x86-64.so.2...
  (No debugging symbols found in /lib64/ld-linux-x86-64.so.2)
  0x00007fa9d9c121e7 in nanosleep () from /lib64/libc.so.6
  (gdb) bt
  #0  0x00007fa9d9c121e7 in nanosleep () from /lib64/libc.so.6
  #1  0x00007fa9d9c1211e in sleep () from /lib64/libc.so.6
  #2  0x000000000040117e in spin_forever () at attach-test.c:17
  #3  0x0000000000401198 in main () at attach-test.c:24
  (gdb)

which is much better.

I've also tagged the bug PR gdb/29782 which concerns the test
gdb.server/connect-with-no-symbol-file.exp.  After making this change,
when running gdb.server/connect-with-no-symbol-file.exp GDB would now
pick up the /proc/PID/exe file as the executable in some cases.

As GDB is not restarted for the multiple iterations of this test
GDB (or rather BFD) would given a warning/error like:

  (gdb) PASS: gdb.server/connect-with-no-symbol-file.exp: sysroot=target:: action=permission: setup: disconnect
  set sysroot target:
  BFD: reopening /proc/3283001/exe: No such file or directory
  (gdb) FAIL: gdb.server/connect-with-no-symbol-file.exp: sysroot=target:: action=permission: setup: adjust sysroot

What's happening is that an executable found for an earlier iteration
of the test is still registered for the inferior when we are setting
up for a second iteration of the test.  When the sysroot changes, if
there's an executable registered GDB tries to reopen it, but in this
case the file has disappeared (the previous inferior has exited by
this point).

I did think about maybe, when the executable is /proc/PID/exe, we
should auto-delete the file from the inferior.  But in the end I
thought this was a bad idea.  Not only would this require a lot of
special code in GDB just to support this edge case: we'd need to track
if the exe file name came from /proc and should be auto-deleted, or
we'd need target specific code to check if a path should be
auto-deleted.....

... in addition, we'd still want to warn the user when we auto-deleted
the file from the inferior, otherwise they might be surprised to find
their inferior suddenly has no executable attached, so we wouldn't
actually reduce the number of warnings the user sees.

So in the end I figured that the best solution is to just update the
test to avoid the warning.  This is easily done by manually removing
the executable from the inferior once each iteration of the test has
completed.

Now, in bug PR gdb/29782 GDB is clearly managing to pick up an
executable from the NFS cache somehow.  I guess what's happening is
that when the original file is deleted /proc/PID/exe is actually
pointing to a file in the NFS cache which is only deleted at some
later point, and so when GDB starts up we do manage to associate a
file with the inferior, this results in the same message being emitted
from BFD as I was seeing.  The fix included in this commit should also
fix that bug.

One final note:  On x86-64 GNU/Linux, the
gdb.server/connect-with-no-symbol-file.exp test will produce 2 core
files.  This is due to a bug in gdbserver that is nothing to do with
this test.  These core files are created before and after this
commit.  I am working on a fix for the gdbserver issue, but will post
that separately.

Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=28313
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=29782

Approved-By: Tom Tromey <tom@tromey.com>
berenm pushed a commit that referenced this pull request Feb 6, 2024
On arm-linux the linaro CI occasionally reports:
...
 (gdb) up 10
 #4  0x0001b864 in pthread_join ()
 (gdb) FAIL: gdb.threads/staticthreads.exp: up 10
...
while this is expected:
...
 (gdb) up 10
 #3  0x00010568 in main (argc=1, argv=0xfffeede4) at staticthreads.c:76
 76          pthread_join (thread, NULL);
 (gdb) PASS: gdb.threads/staticthreads.exp: up 10
...

Thiago investigated the problem, and using valgrind found an invalid read in
arm_exidx_fill_cache.

The problem happens as follows:
- an objfile and corresponding per_bfd are allocated
- some memory is allocated in arm_exidx_new_objfile using
  objfile->objfile_obstack, for the "exception table entry cache".
- a symbol reread is triggered, and the objfile, including the
  objfile_obstack, is destroyed
- a new objfile is allocated, using the same per_bfd
- again arm_exidx_new_objfile is called, but since the same per_bfd is used,
  it doesn't allocate any new memory for the "exception table entry cache".
- the "exception table entry cache" is accessed by arm_exidx_fill_cache,
  and we have a use-after-free.

This is a regression since commit a2726d4 ("[ARM] Store exception handling
information per-bfd instead of per-objfile"), which changed the "exception
table entry cache" from per-objfile to per-bfd, but failed to update the
obstack_alloc.

Fix this by using objfile->per_bfd->storage_obstack instead of
objfile->objfile_obstack.

I couldn't reproduce the FAIL myself, but Thiago confirmed that the patch
fixes it.

Tested on arm-linux.

Approved-By: Luis Machado <luis.machado@arm.com>

PR tdep/31254
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=31254
berenm pushed a commit that referenced this pull request Feb 7, 2024
On arm-linux the linaro CI occasionally reports:
...
 (gdb) up 10
 #4  0x0001b864 in pthread_join ()
 (gdb) FAIL: gdb.threads/staticthreads.exp: up 10
...
while this is expected:
...
 (gdb) up 10
 #3  0x00010568 in main (argc=1, argv=0xfffeede4) at staticthreads.c:76
 76          pthread_join (thread, NULL);
 (gdb) PASS: gdb.threads/staticthreads.exp: up 10
...

Thiago investigated the problem, and using valgrind found an invalid read in
arm_exidx_fill_cache.

The problem happens as follows:
- an objfile and corresponding per_bfd are allocated
- some memory is allocated in arm_exidx_new_objfile using
  objfile->objfile_obstack, for the "exception table entry cache".
- a symbol reread is triggered, and the objfile, including the
  objfile_obstack, is destroyed
- a new objfile is allocated, using the same per_bfd
- again arm_exidx_new_objfile is called, but since the same per_bfd is used,
  it doesn't allocate any new memory for the "exception table entry cache".
- the "exception table entry cache" is accessed by arm_exidx_fill_cache,
  and we have a use-after-free.

This is a regression since commit a2726d4 ("[ARM] Store exception handling
information per-bfd instead of per-objfile"), which changed the "exception
table entry cache" from per-objfile to per-bfd, but failed to update the
obstack_alloc.

Fix this by using objfile->per_bfd->storage_obstack instead of
objfile->objfile_obstack.

I couldn't reproduce the FAIL myself, but Thiago confirmed that the patch
fixes it.

Tested on arm-linux.

Approved-By: Luis Machado <luis.machado@arm.com>

PR tdep/31254
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=31254
berenm pushed a commit that referenced this pull request Feb 13, 2024
When running test-case gdb.dap/eof.exp, it occasionally coredumps.

The thread triggering the coredump is:
...
 #0  0x0000ffff42bb2280 in __pthread_kill_implementation () from /lib64/libc.so.6
 #1  0x0000ffff42b65800 [PAC] in raise () from /lib64/libc.so.6
 #2  0x00000000007b03e8 [PAC] in handle_fatal_signal (sig=11)
     at gdb/event-top.c:926
 #3  0x00000000007b0470 in handle_sigsegv (sig=11)
     at gdb/event-top.c:976
 #4  <signal handler called>
 #5  0x0000000000606080 in cli_ui_out::do_message (this=0xffff2f7ed728, style=...,
     format=0xffff0c002af1 "%s", args=...) at gdb/cli-out.c:232
 #6  0x0000000000ce6358 in ui_out::call_do_message (this=0xffff2f7ed728, style=...,
     format=0xffff0c002af1 "%s") at gdb/ui-out.c:584
 #7  0x0000000000ce6610 in ui_out::vmessage (this=0xffff2f7ed728, in_style=...,
     format=0x16f93ea "", args=...) at gdb/ui-out.c:621
 #8  0x0000000000ce3a9c in ui_file::vprintf (this=0xfffffbea1b18, ...)
     at gdb/ui-file.c:74
 #9  0x0000000000d2b148 in gdb_vprintf (stream=0xfffffbea1b18, format=0x16f93e8 "%s",
     args=...) at gdb/utils.c:1898
 #10 0x0000000000d2b23c in gdb_printf (stream=0xfffffbea1b18, format=0x16f93e8 "%s")
     at gdb/utils.c:1913
 #11 0x0000000000ab5208 in gdbpy_write (self=0x33fe35d0, args=0x342ec280, kw=0x345c08b0)
     at gdb/python/python.c:1464
 #12 0x0000ffff434acedc in cfunction_call () from /lib64/libpython3.12.so.1.0
 #13 0x0000ffff4347c500 [PAC] in _PyObject_MakeTpCall ()
     from /lib64/libpython3.12.so.1.0
 #14 0x0000ffff43488b64 [PAC] in _PyEval_EvalFrameDefault ()
    from /lib64/libpython3.12.so.1.0
 #15 0x0000ffff434d8cd0 [PAC] in method_vectorcall () from /lib64/libpython3.12.so.1.0
 #16 0x0000ffff434b9824 [PAC] in PyObject_CallOneArg () from /lib64/libpython3.12.so.1.0
 #17 0x0000ffff43557674 [PAC] in PyFile_WriteObject () from /lib64/libpython3.12.so.1.0
 #18 0x0000ffff435577a0 [PAC] in PyFile_WriteString () from /lib64/libpython3.12.so.1.0
 #19 0x0000ffff43465354 [PAC] in thread_excepthook () from /lib64/libpython3.12.so.1.0
 #20 0x0000ffff434ac6e0 [PAC] in cfunction_vectorcall_O ()
    from /lib64/libpython3.12.so.1.0
 #21 0x0000ffff434a32d8 [PAC] in PyObject_Vectorcall () from /lib64/libpython3.12.so.1.0
 #22 0x0000ffff43488b64 [PAC] in _PyEval_EvalFrameDefault ()
    from /lib64/libpython3.12.so.1.0
 #23 0x0000ffff434d8d88 [PAC] in method_vectorcall () from /lib64/libpython3.12.so.1.0
 #24 0x0000ffff435e0ef4 [PAC] in thread_run () from /lib64/libpython3.12.so.1.0
 #25 0x0000ffff43591ec0 [PAC] in pythread_wrapper () from /lib64/libpython3.12.so.1.0
 #26 0x0000ffff42bb0584 [PAC] in start_thread () from /lib64/libc.so.6
 #27 0x0000ffff42c1fd4c [PAC] in thread_start () from /lib64/libc.so.6
...

The direct cause for the coredump seems to be that cli_ui_out::do_message
is trying to write to a stream variable which does not look sound:
...
(gdb) p *stream
$8 = {_vptr.ui_file = 0x0, m_applied_style = {m_foreground = {m_simple = true, {
        m_value = 0, {m_red = 0 '\000', m_green = 0 '\000', m_blue = 0 '\000'}}},
    m_background = {m_simple = 32, {m_value = 65535, {m_red = 255 '\377',
          m_green = 255 '\377', m_blue = 0 '\000'}}},
    m_intensity = (unknown: 0x438fe710), m_reverse = 255}}
...

The string that is being printed is:
...
(gdb) p str
$9 = "Exception in thread "
...
so AFAICT this is a DAP thread running into an exception and trying to print
it.

If we look at the state of gdb's main thread, we have:
...
 #0  0x0000ffff42bac914 in __futex_abstimed_wait_cancelable64 () from /lib64/libc.so.6
 #1  0x0000ffff42bafb44 [PAC] in pthread_cond_timedwait@@GLIBC_2.17 ()
    from /lib64/libc.so.6
 #2  0x0000ffff43466e9c [PAC] in take_gil () from /lib64/libpython3.12.so.1.0
 #3  0x0000ffff43484fe0 [PAC] in PyEval_RestoreThread ()
     from /lib64/libpython3.12.so.1.0
 #4  0x0000000000ab8698 [PAC] in gdbpy_allow_threads::~gdbpy_allow_threads (
     this=0xfffffbea1cf8, __in_chrg=<optimized out>)
     at gdb/python/python-internal.h:769
 #5  0x0000000000ab2fec in execute_gdb_command (self=0x33fe35d0, args=0x34297b60,
     kw=0x34553d20) at gdb/python/python.c:681
 #6  0x0000ffff434acedc in cfunction_call () from /lib64/libpython3.12.so.1.0
 #7  0x0000ffff4347c500 [PAC] in _PyObject_MakeTpCall ()
     from /lib64/libpython3.12.so.1.0
 #8  0x0000ffff43488b64 [PAC] in _PyEval_EvalFrameDefault ()
    from /lib64/libpython3.12.so.1.0
 #9  0x0000ffff4353bce8 [PAC] in _PyObject_VectorcallTstate.lto_priv.3 ()
    from /lib64/libpython3.12.so.1.0
 #10 0x0000000000ab87fc [PAC] in gdbpy_event::operator() (this=0xffff14005900)
     at gdb/python/python.c:1061
 #11 0x0000000000ab93e8 in std::__invoke_impl<void, gdbpy_event&> (__f=...)
     at /usr/include/c++/13/bits/invoke.h:61
 #12 0x0000000000ab9204 in std::__invoke_r<void, gdbpy_event&> (__fn=...)
     at /usr/include/c++/13/bits/invoke.h:111
 #13 0x0000000000ab8e90 in std::_Function_handler<..>::_M_invoke(...) (...)
     at /usr/include/c++/13/bits/std_function.h:290
 #14 0x000000000062e0d0 in std::function<void ()>::operator()() const (
     this=0xffff14005830) at /usr/include/c++/13/bits/std_function.h:591
 #15 0x0000000000b67f14 in run_events (error=0, client_data=0x0)
     at gdb/run-on-main-thread.c:76
 #16 0x000000000157e290 in handle_file_event (file_ptr=0x33dae3a0, ready_mask=1)
     at gdbsupport/event-loop.cc:573
 #17 0x000000000157e760 in gdb_wait_for_event (block=1)
     at gdbsupport/event-loop.cc:694
 #18 0x000000000157d464 in gdb_do_one_event (mstimeout=-1)
     at gdbsupport/event-loop.cc:264
 #19 0x0000000000943a84 in start_event_loop () at gdb/main.c:401
 #20 0x0000000000943bfc in captured_command_loop () at gdb/main.c:465
 #21 0x000000000094567c in captured_main (data=0xfffffbea23e8)
     at gdb/main.c:1335
 #22 0x0000000000945700 in gdb_main (args=0xfffffbea23e8)
     at gdb/main.c:1354
 #23 0x0000000000423ab4 in main (argc=14, argv=0xfffffbea2578)
     at gdb/gdb.c:39
...

AFAIU, there's a race between the two threads on gdb_stderr:
- the DAP thread samples the gdb_stderr value, and uses it a bit later to
  print to
- the gdb main thread changes the gdb_stderr value forth and back,
  using a temporary value for string capture purposes

The non-sound stream value is caused by gdb_stderr being sampled while
pointing to a str_file object, and used once the str_file object is already
destroyed.

The error here is that the DAP thread attempts to print to gdb_stderr.

Fix this by adding a thread_wrapper that:
- catches all exceptions and logs them to dap.log, and
- while we're at it, logs when exiting
and using the thread_wrapper for each DAP thread.

Tested on aarch64-linux.

Approved-By: Tom Tromey <tom@tromey.com>
berenm pushed a commit that referenced this pull request Feb 14, 2024
When running test-case gdb.reverse/func-map-to-same-line.exp on arm-linux with
target board unix/-mthumb, we run into:
...
(gdb) reverse-step
func2 () at func-map-to-same-line.c:26
26	{
(gdb) FAIL: gdb.reverse/func-map-to-same-line.exp: \
  column_info_flag=column-info: step-test: reverse-step into func2
...

The FAIL is caused by incorrect recording of this insn:
...
4f6:   f85d 7b04       ldr.w   r7, [sp], #4
...

The insn updates the sp, but we don't record this:
...
$ gdb -q -batch func-map-to-same-line \
  -ex "b *func2+8" \
  -ex run \
  -ex record \
  -ex "set debug record 2" \
  -ex stepi
Breakpoint 1 at 0x4f6: file func-map-to-same-line.c, line 27.

Breakpoint 1, 0xaaaaa4f6 in func2 () at func-map-to-same-line.c:27
27	} /* END FUNC2 */
Process record: arm_process_record addr = 0xaaaaa4f6
Process record: add register num = 15 to record list.
Process record: record_full_arch_list_add 0xabc6c460.
Process record: add register num = 7 to record list.
Process record: record_full_arch_list_add 0xabc3b868.
Process record: add register num = 25 to record list.
...
[ Note that sp is r13, and we see here only r15 (pc), r7, and r25 (ps). ]

The problem is that the specific insn, an LDR(immediate) T4, is not handled in
thumb2_record_ld_word.

Fix this by detecting the insn in thumb2_record_ld_word, and recording the
updated base register.

Tested on arm-linux.

Reported-By: Thiago Jung Bauermann <thiago.bauermann@linaro.org>
Approved-By: Luis Machado <luis.machado@arm.com>

PR tdep/31278
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=31278
berenm pushed a commit that referenced this pull request Feb 15, 2024
When running test-case gdb.dap/eof.exp, we're likely to get a coredump due to
a segfault in new_threadstate.

At the point of the core dump, the gdb main thread looks like:
...
 (gdb) bt
 #0  0x0000fffee30d2280 in __pthread_kill_implementation () from /lib64/libc.so.6
 #1  0x0000fffee3085800 [PAC] in raise () from /lib64/libc.so.6
 #2  0x00000000007b03e8 [PAC] in handle_fatal_signal (sig=11)
     at gdb/event-top.c:926
 #3  0x00000000007b0470 in handle_sigsegv (sig=11)
     at gdb/event-top.c:976
 #4  <signal handler called>
 #5  0x0000fffee3a4db14 in new_threadstate () from /lib64/libpython3.12.so.1.0
 #6  0x0000fffee3ab0548 [PAC] in PyGILState_Ensure () from /lib64/libpython3.12.so.1.0
 #7  0x0000000000a6d034 [PAC] in gdbpy_gil::gdbpy_gil (this=0xffffcb279738)
     at gdb/python/python-internal.h:787
 #8  0x0000000000ab87ac in gdbpy_event::~gdbpy_event (this=0xfffea8001ee0,
     __in_chrg=<optimized out>) at gdb/python/python.c:1051
 #9  0x0000000000ab9460 in std::_Function_base::_Base_manager<...>::_M_destroy
     (__victim=...) at /usr/include/c++/13/bits/std_function.h:175
 #10 0x0000000000ab92dc in std::_Function_base::_Base_manager<...>::_M_manager
     (__dest=..., __source=..., __op=std::__destroy_functor)
     at /usr/include/c++/13/bits/std_function.h:203
 #11 0x0000000000ab8f14 in std::_Function_handler<...>::_M_manager(...) (...)
     at /usr/include/c++/13/bits/std_function.h:282
 #12 0x000000000042dd9c in std::_Function_base::~_Function_base (this=0xfffea8001c10,
     __in_chrg=<optimized out>) at /usr/include/c++/13/bits/std_function.h:244
 #13 0x000000000042e654 in std::function<void ()>::~function() (this=0xfffea8001c10,
     __in_chrg=<optimized out>) at /usr/include/c++/13/bits/std_function.h:334
 #14 0x0000000000b68e60 in std::_Destroy<std::function<void ()> >(...) (...)
     at /usr/include/c++/13/bits/stl_construct.h:151
 #15 0x0000000000b68cd0 in std::_Destroy_aux<false>::__destroy<...>(...) (...)
     at /usr/include/c++/13/bits/stl_construct.h:163
 #16 0x0000000000b689d8 in std::_Destroy<...>(...) (...)
     at /usr/include/c++/13/bits/stl_construct.h:196
 #17 0x0000000000b68414 in std::_Destroy<...>(...) (...)
     at /usr/include/c++/13/bits/alloc_traits.h:948
 #18 std::vector<...>::~vector() (this=0x2a183c8 <runnables>)
     at /usr/include/c++/13/bits/stl_vector.h:732
 #19 0x0000fffee3088370 in __run_exit_handlers () from /lib64/libc.so.6
 #20 0x0000fffee3088450 [PAC] in exit () from /lib64/libc.so.6
 #21 0x0000000000c95600 [PAC] in quit_force (exit_arg=0x0, from_tty=0)
     at gdb/top.c:1822
 #22 0x0000000000609140 in quit_command (args=0x0, from_tty=0)
     at gdb/cli/cli-cmds.c:508
 #23 0x0000000000c926a4 in quit_cover () at gdb/top.c:300
 #24 0x00000000007b09d4 in async_disconnect (arg=0x0)
     at gdb/event-top.c:1230
 #25 0x0000000000548acc in invoke_async_signal_handlers ()
     at gdb/async-event.c:234
 #26 0x000000000157d2d4 in gdb_do_one_event (mstimeout=-1)
     at gdbsupport/event-loop.cc:199
 #27 0x0000000000943a84 in start_event_loop () at gdb/main.c:401
 #28 0x0000000000943bfc in captured_command_loop () at gdb/main.c:465
 #29 0x000000000094567c in captured_main (data=0xffffcb279d08)
     at gdb/main.c:1335
 #30 0x0000000000945700 in gdb_main (args=0xffffcb279d08)
     at gdb/main.c:1354
 #31 0x0000000000423ab4 in main (argc=14, argv=0xffffcb279e98)
     at gdb/gdb.c:39
...

The direct cause of the segfault is calling PyGILState_Ensure after
calling Py_Finalize.

AFAICT the problem is a race between the gdb main thread and DAP's JSON writer
thread.

On one side, we have the following events:
- DAP's JSON reader thread reads an EOF, and lets DAP's main thread known
  by writing None into read_queue
- DAP's main thread lets DAP's JSON writer thread known by writing None into
  write_queue
- DAP's JSON writer thread sees the None in its queue, and calls
  send_gdb("quit")
- a corresponding gdbpy_event is deposited in the runnables vector, to be
  run by the gdb main thread

On the other side, we have the following events:
- the gdb main thread receives a SIGHUP
- the corresponding handler calls quit_force, which calls do_final_cleanups
- one of the final cleanups is finalize_python, which calls Py_Finalize
- quit_force calls exit, which triggers the exit handlers
- one of the exit handlers is the destructor of the runnables vector
- destruction of the vector triggers destruction of the remaining element
- the remaining element is a gdbpy_event, and the destructor (indirectly)
  calls PyGILState_Ensure

It's good to note that both events (EOF and SIGHUP) are caused by this line in
the test-case:
...
catch "close -i $gdb_spawn_id"
...
where "expect close" closes the stdin and stdout file descriptors, which
causes the SIGHUP to be send.

So, for the system I'm running this on, the send_gdb("quit") is actually not
needed.

I'm not sure if we support any systems where it's actually needed.

Fix this by removing the send_gdb("quit").

Tested on aarch64-linux.

PR dap/31306
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=31306
berenm pushed a commit that referenced this pull request Feb 20, 2024
When building gdb with -O0 -fsanitize=address, and running test-case
gdb.ada/uninitialized_vars.exp, I run into:
...
(gdb) info locals
a = 0
z = (a => 1, b => false, c => 2.0)
=================================================================
==66372==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x602000097f58 at pc 0xffff52c0da1c bp 0xffffc90a1d40 sp 0xffffc90a1d80
READ of size 4 at 0x602000097f58 thread T0
    #0 0xffff52c0da18 in memmove (/lib64/libasan.so.8+0x6da18)
    #1 0xbcab24 in unsigned char* std::__copy_move_backward<false, true, std::random_access_iterator_tag>::__copy_move_b<unsigned char const, unsigned char>(unsigned char const*, unsigned char const*, unsigned char*) /usr/include/c++/13/bits/stl_algobase.h:748
    #2 0xbc9bf4 in unsigned char* std::__copy_move_backward_a2<false, unsigned char const*, unsigned char*>(unsigned char const*, unsigned char const*, unsigned char*) /usr/include/c++/13/bits/stl_algobase.h:769
    #3 0xbc898c in unsigned char* std::__copy_move_backward_a1<false, unsigned char const*, unsigned char*>(unsigned char const*, unsigned char const*, unsigned char*) /usr/include/c++/13/bits/stl_algobase.h:778
    #4 0xbc715c in unsigned char* std::__copy_move_backward_a<false, unsigned char const*, unsigned char*>(unsigned char const*, unsigned char const*, unsigned char*) /usr/include/c++/13/bits/stl_algobase.h:807
    #5 0xbc4e6c in unsigned char* std::copy_backward<unsigned char const*, unsigned char*>(unsigned char const*, unsigned char const*, unsigned char*) /usr/include/c++/13/bits/stl_algobase.h:867
    #6 0xbc2934 in void gdb::copy<unsigned char const, unsigned char>(gdb::array_view<unsigned char const>, gdb::array_view<unsigned char>) gdb/../gdbsupport/array-view.h:223
    #7 0x20e0100 in value::contents_copy_raw(value*, long, long, long) gdb/value.c:1239
    #8 0x20e9830 in value::primitive_field(long, int, type*) gdb/value.c:3078
    #9 0x20e98f8 in value_field(value*, int) gdb/value.c:3095
    #10 0xcafd64 in print_field_values gdb/ada-valprint.c:658
    #11 0xcb0fa0 in ada_val_print_struct_union gdb/ada-valprint.c:857
    #12 0xcb1bb4 in ada_value_print_inner(value*, ui_file*, int, value_print_options const*) gdb/ada-valprint.c:1042
    #13 0xc66e04 in ada_language::value_print_inner(value*, ui_file*, int, value_print_options const*) const (/home/vries/gdb/build/gdb/gdb+0xc66e04)
    #14 0x20ca1e8 in common_val_print(value*, ui_file*, int, value_print_options const*, language_defn const*) gdb/valprint.c:1092
    #15 0x20caabc in common_val_print_checked(value*, ui_file*, int, value_print_options const*, language_defn const*) gdb/valprint.c:1184
    #16 0x196c524 in print_variable_and_value(char const*, symbol*, frame_info_ptr, ui_file*, int) gdb/printcmd.c:2355
    #17 0x1d99ca0 in print_variable_and_value_data::operator()(char const*, symbol*) gdb/stack.c:2308
    #18 0x1dabca0 in gdb::function_view<void (char const*, symbol*)>::bind<print_variable_and_value_data>(print_variable_and_value_data&)::{lambda(gdb::fv_detail::erased_callable, char const*, symbol*)#1}::operator()(gdb::fv_detail::erased_callable, char const*, symbol*) const gdb/../gdbsupport/function-view.h:305
    #19 0x1dabd14 in gdb::function_view<void (char const*, symbol*)>::bind<print_variable_and_value_data>(print_variable_and_value_data&)::{lambda(gdb::fv_detail::erased_callable, char const*, symbol*)#1}::_FUN(gdb::fv_detail::erased_callable, char const*, symbol*) gdb/../gdbsupport/function-view.h:299
    #20 0x1dab34c in gdb::function_view<void (char const*, symbol*)>::operator()(char const*, symbol*) const gdb/../gdbsupport/function-view.h:289
    #21 0x1d9963c in iterate_over_block_locals gdb/stack.c:2240
    #22 0x1d99790 in iterate_over_block_local_vars(block const*, gdb::function_view<void (char const*, symbol*)>) gdb/stack.c:2259
    #23 0x1d9a598 in print_frame_local_vars gdb/stack.c:2380
    #24 0x1d9afac in info_locals_command(char const*, int) gdb/stack.c:2458
    #25 0xfd7b30 in do_simple_func gdb/cli/cli-decode.c:95
    #26 0xfe5a2c in cmd_func(cmd_list_element*, char const*, int) gdb/cli/cli-decode.c:2735
    #27 0x1f03790 in execute_command(char const*, int) gdb/top.c:575
    #28 0x1384080 in command_handler(char const*) gdb/event-top.c:566
    #29 0x1384e2c in command_line_handler(std::unique_ptr<char, gdb::xfree_deleter<char> >&&) gdb/event-top.c:802
    #30 0x1f731e4 in tui_command_line_handler gdb/tui/tui-interp.c:104
    #31 0x1382a58 in gdb_rl_callback_handler gdb/event-top.c:259
    #32 0x21dbb80 in rl_callback_read_char readline/readline/callback.c:290
    #33 0x1382510 in gdb_rl_callback_read_char_wrapper_noexcept gdb/event-top.c:195
    #34 0x138277c in gdb_rl_callback_read_char_wrapper gdb/event-top.c:234
    #35 0x1fe9b40 in stdin_event_handler gdb/ui.c:155
    #36 0x35ff1bc in handle_file_event gdbsupport/event-loop.cc:573
    #37 0x35ff9d8 in gdb_wait_for_event gdbsupport/event-loop.cc:694
    #38 0x35fd284 in gdb_do_one_event(int) gdbsupport/event-loop.cc:264
    #39 0x1768080 in start_event_loop gdb/main.c:408
    #40 0x17684c4 in captured_command_loop gdb/main.c:472
    #41 0x176cfc8 in captured_main gdb/main.c:1342
    #42 0x176d088 in gdb_main(captured_main_args*) gdb/main.c:1361
    #43 0xb73edc in main gdb/gdb.c:39
    #44 0xffff519b09d8 in __libc_start_call_main (/lib64/libc.so.6+0x309d8)
    #45 0xffff519b0aac in __libc_start_main@@GLIBC_2.34 (/lib64/libc.so.6+0x30aac)
    #46 0xb73c2c in _start (/home/vries/gdb/build/gdb/gdb+0xb73c2c)

0x602000097f58 is located 0 bytes after 8-byte region [0x602000097f50,0x602000097f58)
allocated by thread T0 here:
    #0 0xffff52c65218 in calloc (/lib64/libasan.so.8+0xc5218)
    #1 0xcbc278 in xcalloc gdb/alloc.c:97
    #2 0x35f21e8 in xzalloc(unsigned long) gdbsupport/common-utils.cc:29
    #3 0x20de270 in value::allocate_contents(bool) gdb/value.c:937
    #4 0x20edc08 in value::fetch_lazy() gdb/value.c:4033
    #5 0x20dadc0 in value::entirely_covered_by_range_vector(std::vector<range, std::allocator<range> > const&) gdb/value.c:229
    #6 0xcb2298 in value::entirely_optimized_out() gdb/value.h:560
    #7 0x20ca6fc in value_check_printable gdb/valprint.c:1133
    #8 0x20caa8c in common_val_print_checked(value*, ui_file*, int, value_print_options const*, language_defn const*) gdb/valprint.c:1182
    #9 0x196c524 in print_variable_and_value(char const*, symbol*, frame_info_ptr, ui_file*, int) gdb/printcmd.c:2355
    #10 0x1d99ca0 in print_variable_and_value_data::operator()(char const*, symbol*) gdb/stack.c:2308
    #11 0x1dabca0 in gdb::function_view<void (char const*, symbol*)>::bind<print_variable_and_value_data>(print_variable_and_value_data&)::{lambda(gdb::fv_detail::erased_callable, char const*, symbol*)#1}::operator()(gdb::fv_detail::erased_callable, char const*, symbol*) const gdb/../gdbsupport/function-view.h:305
    #12 0x1dabd14 in gdb::function_view<void (char const*, symbol*)>::bind<print_variable_and_value_data>(print_variable_and_value_data&)::{lambda(gdb::fv_detail::erased_callable, char const*, symbol*)#1}::_FUN(gdb::fv_detail::erased_callable, char const*, symbol*) gdb/../gdbsupport/function-view.h:299
    #13 0x1dab34c in gdb::function_view<void (char const*, symbol*)>::operator()(char const*, symbol*) const gdb/../gdbsupport/function-view.h:289
    #14 0x1d9963c in iterate_over_block_locals gdb/stack.c:2240
    #15 0x1d99790 in iterate_over_block_local_vars(block const*, gdb::function_view<void (char const*, symbol*)>) gdb/stack.c:2259
    #16 0x1d9a598 in print_frame_local_vars gdb/stack.c:2380
    #17 0x1d9afac in info_locals_command(char const*, int) gdb/stack.c:2458
    #18 0xfd7b30 in do_simple_func gdb/cli/cli-decode.c:95
    #19 0xfe5a2c in cmd_func(cmd_list_element*, char const*, int) gdb/cli/cli-decode.c:2735
    #20 0x1f03790 in execute_command(char const*, int) gdb/top.c:575
    #21 0x1384080 in command_handler(char const*) gdb/event-top.c:566
    #22 0x1384e2c in command_line_handler(std::unique_ptr<char, gdb::xfree_deleter<char> >&&) gdb/event-top.c:802
    #23 0x1f731e4 in tui_command_line_handler gdb/tui/tui-interp.c:104
    #24 0x1382a58 in gdb_rl_callback_handler gdb/event-top.c:259
    #25 0x21dbb80 in rl_callback_read_char readline/readline/callback.c:290
    #26 0x1382510 in gdb_rl_callback_read_char_wrapper_noexcept gdb/event-top.c:195
    #27 0x138277c in gdb_rl_callback_read_char_wrapper gdb/event-top.c:234
    #28 0x1fe9b40 in stdin_event_handler gdb/ui.c:155
    #29 0x35ff1bc in handle_file_event gdbsupport/event-loop.cc:573

SUMMARY: AddressSanitizer: heap-buffer-overflow (/lib64/libasan.so.8+0x6da18) in memmove
...

The error happens when trying to print either variable y or y2:
...
   type Variable_Record (A : Boolean := True) is record
      case A is
         when True =>
            B : Integer;
         when False =>
            C : Float;
            D : Integer;
      end case;
   end record;
   Y  : Variable_Record := (A => True, B => 1);
   Y2 : Variable_Record := (A => False, C => 1.0, D => 2);
...
when the variables are uninitialized.

The error happens only when printing the entire variable:
...
(gdb) p y.a
$2 = 216
(gdb) p y.b
There is no member named b.
(gdb) p y.c
$3 = 9.18340949e-41
(gdb) p y.d
$4 = 1
(gdb) p y
<AddressSanitizer: heap-buffer-overflow>
...

The error happens as follows:
- field a functions as discriminant, choosing either the b, or c+d variant.
- when y.a happens to be set to 216, as above, gdb interprets this as the
  variable having the c+d variant (which is why trying to print y.b fails).
- when printing y, gdb allocates a value, copies the bytes into it from the
  target, and then prints the value.
- gdb allocates the value using the type size, which is 8.  It's 8 because
  that's what the DW_AT_byte_size indicates.  Note that for valid values of a,
  it gives correct results: if a is 0 (c+d variant), size is 12, if a is 1
  (b variant), size is 8.
- gdb tries to print field d, which is at an 8 byte offset, and that results
  in a out-of-bounds access for the allocated 8-byte value.

Fix this by handling this case in value::contents_copy_raw, such that we have:
...
(gdb) p y
$1 = (a => 24, c => 9.18340949e-41,
      d => <error reading variable: access outside bounds of object>)
...

An alternative (additional) fix could be this: in compute_variant_fields_inner
gdb reads the discriminant y.a to decide which variant is active.  It would be
nice to detect that the value (y.a == 24) is not a valid Boolean, and give up
on choosing a variant altoghether.  However, the situation regarding the
internal type CODE_TYPE_BOOL is currently ambiguous (see PR31282) and it's not
possible to reliably decide what valid values are.

The test-case source file gdb.ada/uninitialized-variable-record/parse.adb is
a reduced version of gdb.ada/uninitialized_vars/parse.adb, so it copies the
copyright years.

Note that the test-case needs gcc-12 or newer, it's unsupported for older gcc
versions. [ So, it would be nice to rewrite it into a dwarf assembly
test-case. ]

The test-case loops over all languages.  This is inherited from an earlier
attempt to fix this, which had language-specific fixes (in print_field_values,
cp_print_value_fields, pascal_object_print_value_fields and
f_language::value_print_inner).  I've left this in, but I suppose it's not
strictly necessary anymore.

Tested on x86_64-linux.

PR exp/31258
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=31258
berenm pushed a commit that referenced this pull request Feb 20, 2024
From the Python API, we can execute GDB commands via gdb.execute.  If
the command gives an exception, however, we need to recover the GDB
prompt and enable stdin, because the exception does not reach
top-level GDB or normal_stop.  This was done in commit

  commit 1ba1ac8
  Author: Andrew Burgess <andrew.burgess@embecosm.com>
  Date:   Tue Nov 19 11:17:20 2019 +0000

    gdb: Enable stdin on exception in execute_gdb_command

with the following code:

  catch (const gdb_exception &except)
    {
      /* If an exception occurred then we won't hit normal_stop (), or have
         an exception reach the top level of the event loop, which are the
         two usual places in which stdin would be re-enabled. So, before we
         convert the exception and continue back in Python, we should
         re-enable stdin here.  */
      async_enable_stdin ();
      GDB_PY_HANDLE_EXCEPTION (except);
    }

In this patch, we explain what happens when we run a GDB command in
the context of a synchronous command, e.g.  via Python observer
notifications.

As an example, suppose we have the following objfile event listener,
specified in a file named file.py:

~~~
import gdb

class MyListener:
    def __init__(self):
        gdb.events.new_objfile.connect(self.handle_new_objfile_event)
        self.processed_objfile = False

    def handle_new_objfile_event(self, event):
        if self.processed_objfile:
            return

        print("loading " + event.new_objfile.filename)
        self.processed_objfile = True
        gdb.execute('add-inferior -no-connection')
        gdb.execute('inferior 2')
        gdb.execute('target remote | gdbserver - /tmp/a.out')
        gdb.execute('inferior 1')

the_listener = MyListener()
~~~

Using this Python file, we see the behavior below:

  $ gdb -q -ex "source file.py" -ex "run" --args a.out
  Reading symbols from a.out...
  Starting program: /tmp/a.out
  loading /lib64/ld-linux-x86-64.so.2
  [New inferior 2]
  Added inferior 2
  [Switching to inferior 2 [<null>] (<noexec>)]
  stdin/stdout redirected
  Process /tmp/a.out created; pid = 3075406
  Remote debugging using stdio
  Reading /tmp/a.out from remote target...
  ...
  [Switching to inferior 1 [process 3075400] (/tmp/a.out)]
  [Switching to thread 1.1 (process 3075400)]
  #0  0x00007ffff7fe3290 in ?? () from /lib64/ld-linux-x86-64.so.2
  (gdb) [Thread debugging using libthread_db enabled]
  Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
  [Inferior 1 (process 3075400) exited normally]

Note how the GDB prompt comes in-between the debugger output.  We have this
obscure behavior, because the executed command, "target remote", triggers
an invocation of `normal_stop` that enables stdin.  After that, however,
the Python notification context completes and GDB continues with its normal
flow of executing the 'run' command.  This can be seen in the call stack
below:

  (top-gdb) bt
  #0  async_enable_stdin () at src/gdb/event-top.c:523
  #1  0x00005555561c3acd in normal_stop () at src/gdb/infrun.c:9432
  #2  0x00005555561b328e in start_remote (from_tty=0) at src/gdb/infrun.c:3801
  #3  0x0000555556441224 in remote_target::start_remote_1 (this=0x5555587882e0, from_tty=0, extended_p=0) at src/gdb/remote.c:5225
  #4  0x000055555644166c in remote_target::start_remote (this=0x5555587882e0, from_tty=0, extended_p=0) at src/gdb/remote.c:5316
  #5  0x00005555564430cf in remote_target::open_1 (name=0x55555878525e "| gdbserver - /tmp/a.out", from_tty=0, extended_p=0) at src/gdb/remote.c:6175
  #6  0x0000555556441707 in remote_target::open (name=0x55555878525e "| gdbserver - /tmp/a.out", from_tty=0) at src/gdb/remote.c:5338
  #7  0x00005555565ea63f in open_target (args=0x55555878525e "| gdbserver - /tmp/a.out", from_tty=0, command=0x555558589280)  at src/gdb/target.c:824
  #8  0x0000555555f0d89a in cmd_func (cmd=0x555558589280, args=0x55555878525e "| gdbserver - /tmp/a.out", from_tty=0) at src/gdb/cli/cli-decode.c:2735
  #9  0x000055555661fb42 in execute_command (p=0x55555878529e "t", from_tty=0) at src/gdb/top.c:575
  #10 0x0000555555f1a506 in execute_control_command_1 (cmd=0x555558756f00, from_tty=0) at src/gdb/cli/cli-script.c:529
  #11 0x0000555555f1abea in execute_control_command (cmd=0x555558756f00, from_tty=0) at src/gdb/cli/cli-script.c:701
  #12 0x0000555555f19fc7 in execute_control_commands (cmdlines=0x555558756f00, from_tty=0) at src/gdb/cli/cli-script.c:411
  #13 0x0000555556400d91 in execute_gdb_command (self=0x7ffff43b5d00, args=0x7ffff440ab60, kw=0x0) at src/gdb/python/python.c:700
  #14 0x00007ffff7a96023 in ?? () from /lib/x86_64-linux-gnu/libpython3.10.so.1.0
  #15 0x00007ffff7a4dadc in _PyObject_MakeTpCall () from /lib/x86_64-linux-gnu/libpython3.10.so.1.0
  #16 0x00007ffff79e9a1c in _PyEval_EvalFrameDefault () from /lib/x86_64-linux-gnu/libpython3.10.so.1.0
  #17 0x00007ffff7b303af in ?? () from /lib/x86_64-linux-gnu/libpython3.10.so.1.0
  #18 0x00007ffff7a50358 in ?? () from /lib/x86_64-linux-gnu/libpython3.10.so.1.0
  #19 0x00007ffff7a4f3f4 in ?? () from /lib/x86_64-linux-gnu/libpython3.10.so.1.0
  #20 0x00007ffff7a4f883 in PyObject_CallFunctionObjArgs () from /lib/x86_64-linux-gnu/libpython3.10.so.1.0
  #21 0x00005555563a9758 in evpy_emit_event (event=0x7ffff42b5430, registry=0x7ffff42b4690) at src/gdb/python/py-event.c:104
  #22 0x00005555563cb874 in emit_new_objfile_event (objfile=0x555558761700) at src/gdb/python/py-newobjfileevent.c:52
  #23 0x00005555563b53bc in python_new_objfile (objfile=0x555558761700) at src/gdb/python/py-inferior.c:195
  #24 0x0000555555d6dff0 in std::__invoke_impl<void, void (*&)(objfile*), objfile*> (__f=@0x5555585b5860: 0x5555563b5360 <python_new_objfile(objfile*)>) at /usr/include/c++/11/bits/invoke.h:61
  #25 0x0000555555d6be18 in std::__invoke_r<void, void (*&)(objfile*), objfile*> (__fn=@0x5555585b5860: 0x5555563b5360 <python_new_objfile(objfile*)>) at /usr/include/c++/11/bits/invoke.h:111
  #26 0x0000555555d69661 in std::_Function_handler<void (objfile*), void (*)(objfile*)>::_M_invoke(std::_Any_data const&, objfile*&&) (__functor=..., __args#0=@0x7fffffffd080: 0x555558761700) at /usr/include/c++/11/bits/std_function.h:290
  #27 0x0000555556314caf in std::function<void (objfile*)>::operator()(objfile*) const (this=0x5555585b5860, __args#0=0x555558761700) at /usr/include/c++/11/bits/std_function.h:590
  #28 0x000055555631444e in gdb::observers::observable<objfile*>::notify (this=0x55555836eea0 <gdb::observers::new_objfile>, args#0=0x555558761700) at src/gdb/../gdbsupport/observable.h:166
  #29 0x0000555556599b3f in symbol_file_add_with_addrs (abfd=..., name=0x55555875d310 "/lib64/ld-linux-x86-64.so.2", add_flags=..., addrs=0x7fffffffd2f0, flags=..., parent=0x0) at src/gdb/symfile.c:1125
  #30 0x0000555556599ca4 in symbol_file_add_from_bfd (abfd=..., name=0x55555875d310 "/lib64/ld-linux-x86-64.so.2", add_flags=..., addrs=0x7fffffffd2f0, flags=..., parent=0x0) at src/gdb/symfile.c:1160
  #31 0x0000555556546371 in solib_read_symbols (so=..., flags=...) at src/gdb/solib.c:692
  #32 0x0000555556546f0f in solib_add (pattern=0x0, from_tty=0, readsyms=1) at src/gdb/solib.c:1015
  #33 0x0000555556539891 in enable_break (info=0x55555874e180, from_tty=0) at src/gdb/solib-svr4.c:2416
  #34 0x000055555653b305 in svr4_solib_create_inferior_hook (from_tty=0) at src/gdb/solib-svr4.c:3058
  #35 0x0000555556547cee in solib_create_inferior_hook (from_tty=0) at src/gdb/solib.c:1217
  #36 0x0000555556196f6a in post_create_inferior (from_tty=0) at src/gdb/infcmd.c:275
  #37 0x0000555556197670 in run_command_1 (args=0x0, from_tty=1, run_how=RUN_NORMAL) at src/gdb/infcmd.c:486
  #38 0x000055555619783f in run_command (args=0x0, from_tty=1) at src/gdb/infcmd.c:512
  #39 0x0000555555f0798d in do_simple_func (args=0x0, from_tty=1, c=0x555558567510) at src/gdb/cli/cli-decode.c:95
  #40 0x0000555555f0d89a in cmd_func (cmd=0x555558567510, args=0x0, from_tty=1) at src/gdb/cli/cli-decode.c:2735
  #41 0x000055555661fb42 in execute_command (p=0x7fffffffe2c4 "", from_tty=1) at src/gdb/top.c:575
  #42 0x000055555626303b in catch_command_errors (command=0x55555661f4ab <execute_command(char const*, int)>, arg=0x7fffffffe2c1 "run", from_tty=1, do_bp_actions=true) at src/gdb/main.c:513
  #43 0x000055555626328a in execute_cmdargs (cmdarg_vec=0x7fffffffdaf0, file_type=CMDARG_FILE, cmd_type=CMDARG_COMMAND, ret=0x7fffffffda3c) at src/gdb/main.c:612
  #44 0x0000555556264849 in captured_main_1 (context=0x7fffffffdd40) at src/gdb/main.c:1293
  #45 0x0000555556264a7f in captured_main (data=0x7fffffffdd40) at src/gdb/main.c:1314
  #46 0x0000555556264b2e in gdb_main (args=0x7fffffffdd40) at src/gdb/main.c:1343
  #47 0x0000555555ceccab in main (argc=9, argv=0x7fffffffde78) at src/gdb/gdb.c:39
  (top-gdb)

The use of the "target remote" command here is just an example.  In
principle, we would reproduce the problem with any command that
triggers an invocation of `normal_stop`.

To omit enabling the stdin in `normal_stop`, we would have to check the
context we are in.  Since we cannot do that, we add a new field to
`struct ui` to track whether the prompt was already blocked, and set
the tracker flag in the Python context before executing a GDB command.

After applying this patch, the output becomes

  ...
  Reading symbols from a.out...
  Starting program: /tmp/a.out
  loading /lib64/ld-linux-x86-64.so.2
  [New inferior 2]
  Added inferior 2
  [Switching to inferior 2 [<null>] (<noexec>)]
  stdin/stdout redirected
  Process /tmp/a.out created; pid = 3032261
  Remote debugging using stdio
  Reading /tmp/a.out from remote target...
  ...
  [Switching to inferior 1 [process 3032255] (/tmp/a.out)]
  [Switching to thread 1.1 (process 3032255)]
  #0  0x00007ffff7fe3290 in ?? () from /lib64/ld-linux-x86-64.so.2
  [Thread debugging using libthread_db enabled]
  Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
  [Inferior 1 (process 3032255) exited normally]
  (gdb)

Let's now consider a secondary scenario, where the command executed from
the Python raises an error.  As an example, suppose we have the Python
file below:

    def handle_new_objfile_event(self, event):
        ...
        print("loading " + event.new_objfile.filename)
        self.processed_objfile = True
        gdb.execute('print a')

The executed command, "print a", gives an error because "a" is not
defined.  Without this patch, we see the behavior below, where the
prompt is again placed incorrectly:

  ...
  Reading symbols from /tmp/a.out...
  Starting program: /tmp/a.out
  loading /lib64/ld-linux-x86-64.so.2
  Python Exception <class 'gdb.error'>: No symbol "a" in current context.
  (gdb) [Inferior 1 (process 3980401) exited normally]

This time, `async_enable_stdin` is called from the 'catch' block in
`execute_gdb_command`:

  (top-gdb) bt
  #0  async_enable_stdin () at src/gdb/event-top.c:523
  #1  0x0000555556400f0a in execute_gdb_command (self=0x7ffff43b5d00, args=0x7ffff440ab60, kw=0x0) at src/gdb/python/python.c:713
  #2  0x00007ffff7a96023 in ?? () from /lib/x86_64-linux-gnu/libpython3.10.so.1.0
  #3  0x00007ffff7a4dadc in _PyObject_MakeTpCall () from /lib/x86_64-linux-gnu/libpython3.10.so.1.0
  #4  0x00007ffff79e9a1c in _PyEval_EvalFrameDefault () from /lib/x86_64-linux-gnu/libpython3.10.so.1.0
  #5  0x00007ffff7b303af in ?? () from /lib/x86_64-linux-gnu/libpython3.10.so.1.0
  #6  0x00007ffff7a50358 in ?? () from /lib/x86_64-linux-gnu/libpython3.10.so.1.0
  #7  0x00007ffff7a4f3f4 in ?? () from /lib/x86_64-linux-gnu/libpython3.10.so.1.0
  #8  0x00007ffff7a4f883 in PyObject_CallFunctionObjArgs () from /lib/x86_64-linux-gnu/libpython3.10.so.1.0
  #9  0x00005555563a9758 in evpy_emit_event (event=0x7ffff42b5430, registry=0x7ffff42b4690) at src/gdb/python/py-event.c:104
  #10 0x00005555563cb874 in emit_new_objfile_event (objfile=0x555558761410) at src/gdb/python/py-newobjfileevent.c:52
  #11 0x00005555563b53bc in python_new_objfile (objfile=0x555558761410) at src/gdb/python/py-inferior.c:195
  #12 0x0000555555d6dff0 in std::__invoke_impl<void, void (*&)(objfile*), objfile*> (__f=@0x5555585b5860: 0x5555563b5360 <python_new_objfile(objfile*)>) at /usr/include/c++/11/bits/invoke.h:61
  #13 0x0000555555d6be18 in std::__invoke_r<void, void (*&)(objfile*), objfile*> (__fn=@0x5555585b5860: 0x5555563b5360 <python_new_objfile(objfile*)>) at /usr/include/c++/11/bits/invoke.h:111
  #14 0x0000555555d69661 in std::_Function_handler<void (objfile*), void (*)(objfile*)>::_M_invoke(std::_Any_data const&, objfile*&&) (__functor=..., __args#0=@0x7fffffffd080: 0x555558761410) at /usr/include/c++/11/bits/std_function.h:290
  #15 0x0000555556314caf in std::function<void (objfile*)>::operator()(objfile*) const (this=0x5555585b5860, __args#0=0x555558761410) at /usr/include/c++/11/bits/std_function.h:590
  #16 0x000055555631444e in gdb::observers::observable<objfile*>::notify (this=0x55555836eea0 <gdb::observers::new_objfile>, args#0=0x555558761410) at src/gdb/../gdbsupport/observable.h:166
  #17 0x0000555556599b3f in symbol_file_add_with_addrs (abfd=..., name=0x55555875d020 "/lib64/ld-linux-x86-64.so.2", add_flags=..., addrs=0x7fffffffd2f0, flags=..., parent=0x0) at src/gdb/symfile.c:1125
  #18 0x0000555556599ca4 in symbol_file_add_from_bfd (abfd=..., name=0x55555875d020 "/lib64/ld-linux-x86-64.so.2", add_flags=..., addrs=0x7fffffffd2f0, flags=..., parent=0x0) at src/gdb/symfile.c:1160
  #19 0x0000555556546371 in solib_read_symbols (so=..., flags=...) at src/gdb/solib.c:692
  #20 0x0000555556546f0f in solib_add (pattern=0x0, from_tty=0, readsyms=1) at src/gdb/solib.c:1015
  #21 0x0000555556539891 in enable_break (info=0x55555874a670, from_tty=0) at src/gdb/solib-svr4.c:2416
  #22 0x000055555653b305 in svr4_solib_create_inferior_hook (from_tty=0) at src/gdb/solib-svr4.c:3058
  #23 0x0000555556547cee in solib_create_inferior_hook (from_tty=0) at src/gdb/solib.c:1217
  #24 0x0000555556196f6a in post_create_inferior (from_tty=0) at src/gdb/infcmd.c:275
  #25 0x0000555556197670 in run_command_1 (args=0x0, from_tty=1, run_how=RUN_NORMAL) at src/gdb/infcmd.c:486
  #26 0x000055555619783f in run_command (args=0x0, from_tty=1) at src/gdb/infcmd.c:512
  #27 0x0000555555f0798d in do_simple_func (args=0x0, from_tty=1, c=0x555558567510) at src/gdb/cli/cli-decode.c:95
  #28 0x0000555555f0d89a in cmd_func (cmd=0x555558567510, args=0x0, from_tty=1) at src/gdb/cli/cli-decode.c:2735
  #29 0x000055555661fb42 in execute_command (p=0x7fffffffe2c4 "", from_tty=1) at src/gdb/top.c:575
  #30 0x000055555626303b in catch_command_errors (command=0x55555661f4ab <execute_command(char const*, int)>, arg=0x7fffffffe2c1 "run", from_tty=1, do_bp_actions=true) at src/gdb/main.c:513
  #31 0x000055555626328a in execute_cmdargs (cmdarg_vec=0x7fffffffdaf0, file_type=CMDARG_FILE, cmd_type=CMDARG_COMMAND, ret=0x7fffffffda3c) at src/gdb/main.c:612
  #32 0x0000555556264849 in captured_main_1 (context=0x7fffffffdd40) at src/gdb/main.c:1293
  #33 0x0000555556264a7f in captured_main (data=0x7fffffffdd40) at src/gdb/main.c:1314
  #34 0x0000555556264b2e in gdb_main (args=0x7fffffffdd40) at src/gdb/main.c:1343
  #35 0x0000555555ceccab in main (argc=9, argv=0x7fffffffde78) at src/gdb/gdb.c:39
  (top-gdb)

Again, after we enable stdin, GDB continues with its normal flow
of the 'run' command and receives the inferior's exit event, where
it would have enabled stdin, if we had not done it prematurely.

  (top-gdb) bt
  #0  async_enable_stdin () at src/gdb/event-top.c:523
  #1  0x00005555561c3acd in normal_stop () at src/gdb/infrun.c:9432
  #2  0x00005555561b5bf1 in fetch_inferior_event () at src/gdb/infrun.c:4700
  #3  0x000055555618d6a7 in inferior_event_handler (event_type=INF_REG_EVENT) at src/gdb/inf-loop.c:42
  #4  0x000055555620ecdb in handle_target_event (error=0, client_data=0x0) at src/gdb/linux-nat.c:4316
  #5  0x0000555556f33035 in handle_file_event (file_ptr=0x5555587024e0, ready_mask=1) at src/gdbsupport/event-loop.cc:573
  #6  0x0000555556f3362f in gdb_wait_for_event (block=0) at src/gdbsupport/event-loop.cc:694
  #7  0x0000555556f322cd in gdb_do_one_event (mstimeout=-1) at src/gdbsupport/event-loop.cc:217
  #8  0x0000555556262df8 in start_event_loop () at src/gdb/main.c:407
  #9  0x0000555556262f85 in captured_command_loop () at src/gdb/main.c:471
  #10 0x0000555556264a84 in captured_main (data=0x7fffffffdd40) at src/gdb/main.c:1324
  #11 0x0000555556264b2e in gdb_main (args=0x7fffffffdd40) at src/gdb/main.c:1343
  #12 0x0000555555ceccab in main (argc=9, argv=0x7fffffffde78) at src/gdb/gdb.c:39
  (top-gdb)

The solution implemented by this patch addresses the problem.  After
applying the patch, the output becomes

  $ gdb -q -ex "source file.py" -ex "run" --args a.out
  Reading symbols from /tmp/a.out...
  Starting program: /tmp/a.out
  loading /lib64/ld-linux-x86-64.so.2
  Python Exception <class 'gdb.error'>: No symbol "a" in current context.
  [Inferior 1 (process 3984511) exited normally]
  (gdb)

Regression-tested on X86_64 Linux using the default board file (i.e.  unix).

Co-Authored-By: Oguzhan Karakaya <oguzhan.karakaya@intel.com>
Reviewed-By: Guinevere Larsen <blarsen@redhat.com>
Approved-By: Tom Tromey <tom@tromey.com>
berenm pushed a commit that referenced this pull request Mar 29, 2024
…ro linux

When running test-case gdb.threads/attach-stopped.exp on aarch64-linux, using
the manjaro linux distro, I get:
...
 (gdb) thread apply all bt^M
 ^M
 Thread 2 (Thread 0xffff8d8af120 (LWP 278116) "attach-stopped"):^M
 #0  0x0000ffff8d964864 in clock_nanosleep () from /usr/lib/libc.so.6^M
 #1  0x0000ffff8d969cac in nanosleep () from /usr/lib/libc.so.6^M
 #2  0x0000ffff8d969b68 in sleep () from /usr/lib/libc.so.6^M
 #3  0x0000aaaade370828 in func (arg=0x0) at attach-stopped.c:29^M
 #4  0x0000ffff8d930aec in ?? () from /usr/lib/libc.so.6^M
 #5  0x0000ffff8d99a5dc in ?? () from /usr/lib/libc.so.6^M
 ^M
 Thread 1 (Thread 0xffff8db62020 (LWP 278111) "attach-stopped"):^M
 #0  0x0000ffff8d92d2d8 in ?? () from /usr/lib/libc.so.6^M
 #1  0x0000ffff8d9324b8 in ?? () from /usr/lib/libc.so.6^M
 #2  0x0000aaaade37086c in main () at attach-stopped.c:45^M
 (gdb) FAIL: gdb.threads/attach-stopped.exp: threaded: attach2 to stopped bt
...

The problem is that the test-case expects to see start_thread:
...
	gdb_test "thread apply all bt" ".*sleep.*start_thread.*" \
	    "$threadtype: attach2 to stopped bt"
...
but lack of symbols makes that impossible.

Fix this by allowing " in ?? () from " as well.

Tested on aarch64-linux.

PR testsuite/31451
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=31451
berenm pushed a commit that referenced this pull request Apr 28, 2024
When running test-case gdb.server/connect-with-no-symbol-file.exp on
aarch64-linux (specifically, an opensuse leap 15.5 container on a
fedora asahi 39 system), I run into:
...
(gdb) detach^M
Detaching from program: target:connect-with-no-symbol-file, process 185104^M
Ending remote debugging.^M
terminate called after throwing an instance of 'gdb_exception_error'^M
...

The detailed backtrace of the corefile is:
...
 (gdb) bt
 #0  0x0000ffff75504f54 in raise () from /lib64/libpthread.so.0
 #1  0x00000000007a86b4 in handle_fatal_signal (sig=6)
     at gdb/event-top.c:926
 #2  <signal handler called>
 #3  0x0000ffff74b977b4 in raise () from /lib64/libc.so.6
 #4  0x0000ffff74b98c18 in abort () from /lib64/libc.so.6
 #5  0x0000ffff74ea26f4 in __gnu_cxx::__verbose_terminate_handler() ()
    from /usr/lib64/libstdc++.so.6
 #6  0x0000ffff74ea011c in ?? () from /usr/lib64/libstdc++.so.6
 #7  0x0000ffff74ea0180 in std::terminate() () from /usr/lib64/libstdc++.so.6
 #8  0x0000ffff74ea0464 in __cxa_throw () from /usr/lib64/libstdc++.so.6
 #9  0x0000000001548870 in throw_it (reason=RETURN_ERROR,
     error=TARGET_CLOSE_ERROR, fmt=0x16c7810 "Remote connection closed", ap=...)
     at gdbsupport/common-exceptions.cc:203
 #10 0x0000000001548920 in throw_verror (error=TARGET_CLOSE_ERROR,
     fmt=0x16c7810 "Remote connection closed", ap=...)
     at gdbsupport/common-exceptions.cc:211
 #11 0x0000000001548a00 in throw_error (error=TARGET_CLOSE_ERROR,
     fmt=0x16c7810 "Remote connection closed")
     at gdbsupport/common-exceptions.cc:226
 #12 0x0000000000ac8f2c in remote_target::readchar (this=0x233d3d90, timeout=2)
     at gdb/remote.c:9856
 #13 0x0000000000ac9f04 in remote_target::getpkt (this=0x233d3d90,
     buf=0x233d40a8, forever=false, is_notif=0x0) at gdb/remote.c:10326
 #14 0x0000000000acf3d0 in remote_target::remote_hostio_send_command
     (this=0x233d3d90, command_bytes=13, which_packet=17,
     remote_errno=0xfffff1a3cf38, attachment=0xfffff1a3ce88,
     attachment_len=0xfffff1a3ce90) at gdb/remote.c:12567
 #15 0x0000000000ad03bc in remote_target::fileio_fstat (this=0x233d3d90, fd=3,
     st=0xfffff1a3d020, remote_errno=0xfffff1a3cf38)
     at gdb/remote.c:12979
 #16 0x0000000000c39878 in target_fileio_fstat (fd=0, sb=0xfffff1a3d020,
     target_errno=0xfffff1a3cf38) at gdb/target.c:3315
 #17 0x00000000007eee5c in target_fileio_stream::stat (this=0x233d4400,
     abfd=0x2323fc40, sb=0xfffff1a3d020) at gdb/gdb_bfd.c:467
 #18 0x00000000007f012c in <lambda(bfd*, void*, stat*)>::operator()(bfd *,
     void *, stat *) const (__closure=0x0, abfd=0x2323fc40, stream=0x233d4400,
     sb=0xfffff1a3d020) at gdb/gdb_bfd.c:955
 #19 0x00000000007f015c in <lambda(bfd*, void*, stat*)>::_FUN(bfd *, void *,
     stat *) () at gdb/gdb_bfd.c:956
 #20 0x0000000000f9b838 in opncls_bstat (abfd=0x2323fc40, sb=0xfffff1a3d020)
     at bfd/opncls.c:665
 #21 0x0000000000f90adc in bfd_stat (abfd=0x2323fc40, statbuf=0xfffff1a3d020)
     at bfd/bfdio.c:431
 #22 0x000000000065fe20 in reopen_exec_file () at gdb/corefile.c:52
 #23 0x0000000000c3a3e8 in generic_mourn_inferior ()
     at gdb/target.c:3642
 #24 0x0000000000abf3f0 in remote_unpush_target (target=0x233d3d90)
     at gdb/remote.c:6067
 #25 0x0000000000aca8b0 in remote_target::mourn_inferior (this=0x233d3d90)
     at gdb/remote.c:10587
 #26 0x0000000000c387cc in target_mourn_inferior (
     ptid=<error reading variable: Cannot access memory at address 0x2d310>)
     at gdb/target.c:2738
 #27 0x0000000000abfff0 in remote_target::remote_detach_1 (this=0x233d3d90,
     inf=0x22fce540, from_tty=1) at gdb/remote.c:6421
 #28 0x0000000000ac0094 in remote_target::detach (this=0x233d3d90,
     inf=0x22fce540, from_tty=1) at gdb/remote.c:6436
 #29 0x0000000000c37c3c in target_detach (inf=0x22fce540, from_tty=1)
     at gdb/target.c:2526
 #30 0x0000000000860424 in detach_command (args=0x0, from_tty=1)
    at gdb/infcmd.c:2817
 #31 0x000000000060b594 in do_simple_func (args=0x0, from_tty=1, c=0x231431a0)
     at gdb/cli/cli-decode.c:94
 #32 0x00000000006108c8 in cmd_func (cmd=0x231431a0, args=0x0, from_tty=1)
     at gdb/cli/cli-decode.c:2741
 #33 0x0000000000c65a94 in execute_command (p=0x232e52f6 "", from_tty=1)
     at gdb/top.c:570
 #34 0x00000000007a7d2c in command_handler (command=0x232e52f0 "")
     at gdb/event-top.c:566
 #35 0x00000000007a8290 in command_line_handler (rl=...)
     at gdb/event-top.c:802
 #36 0x0000000000c9092c in tui_command_line_handler (rl=...)
     at gdb/tui/tui-interp.c:103
 #37 0x00000000007a750c in gdb_rl_callback_handler (rl=0x23385330 "detach")
     at gdb/event-top.c:258
 #38 0x0000000000d910f4 in rl_callback_read_char ()
     at readline/readline/callback.c:290
 #39 0x00000000007a7338 in gdb_rl_callback_read_char_wrapper_noexcept ()
     at gdb/event-top.c:194
 #40 0x00000000007a73f0 in gdb_rl_callback_read_char_wrapper
     (client_data=0x22fbf640) at gdb/event-top.c:233
 #41 0x0000000000cbee1c in stdin_event_handler (error=0, client_data=0x22fbf640)
     at gdb/ui.c:154
 #42 0x000000000154ed60 in handle_file_event (file_ptr=0x232be730, ready_mask=1)
     at gdbsupport/event-loop.cc:572
 #43 0x000000000154f21c in gdb_wait_for_event (block=1)
     at gdbsupport/event-loop.cc:693
 #44 0x000000000154dec4 in gdb_do_one_event (mstimeout=-1)
    at gdbsupport/event-loop.cc:263
 #45 0x0000000000910f98 in start_event_loop () at gdb/main.c:400
 #46 0x0000000000911130 in captured_command_loop () at gdb/main.c:464
 #47 0x0000000000912b5c in captured_main (data=0xfffff1a3db58)
     at gdb/main.c:1338
 #48 0x0000000000912bf4 in gdb_main (args=0xfffff1a3db58)
     at gdb/main.c:1357
 #49 0x00000000004170f4 in main (argc=10, argv=0xfffff1a3dcc8)
     at gdb/gdb.c:38
 (gdb)
...

The abort happens because a c++ exception escapes to c code, specifically
opncls_bstat in bfd/opncls.c.  Compiling with -fexceptions works around this.

Fix this by catching the exception just before it escapes, in stat_trampoline
and likewise in few similar spot.

Add a new template catch_exceptions to do so in a consistent way.

Tested on aarch64-linux.

Approved-by: Pedro Alves <pedro@palves.net>

PR remote/31577
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=31577
berenm pushed a commit that referenced this pull request May 16, 2024
Several watchpoint-related testcases, such as
gdb.threads/watchthreads.exp for example, when tested with the backend
in non-stop mode, exposed an interesting detail of the Windows debug
API that wasn't considered before.  The symptom observed is spurious
SIGTRAPs, like:

  Thread 1 "watchthreads" received signal SIGTRAP, Trace/breakpoint trap.
  0x00000001004010b1 in main () at .../src/gdb/testsuite/gdb.threads/watchthreads.c:48
  48              args[i] = 1; usleep (1); /* Init value.  */

After a good amount of staring at logs and headscratching, I realized
the problem:

 #0 - It all starts in the fact that multiple threads can hit an event
      at the same time.  Say, a watchpoint for thread A, and a
      breakpoint for thread B.

 #1 - Say, WaitForDebugEvent reports the breakpoint hit for thread B
      first, then GDB for some reason decides to update debug
      registers, and continue.  Updating debug registers means writing
      the debug registers to _all_ threads, with SetThreadContext.

 #2 - WaitForDebugEvent reports the watchpoint hit for thread A.
      Watchpoint hits are reported as EXCEPTION_SINGLE_STEP.

 #3 - windows-nat checks the Dr6 debug register to check if the step
      was a watchpoint or hardware breakpoint stop, and finds that Dr6
      is completely cleared.  So windows-nat reports a plain SIGTRAP
      (given EXCEPTION_SINGLE_STEP) to the core.

 #4 - Thread A was not supposed to be stepping, so infrun reports the
      SIGTRAP to the user as a random signal.

The strange part is #3 above.  Why was Dr6 cleared?

Turns out what (at least in Windows 10 & 11), writing to _any_ debug
register has the side effect of clearing Dr6, even if you write the
same values the registers already had, back to the registers.

I confirmed it clearly by adding this hack to GDB:

  if (th->context.ContextFlags == 0)
    {
      th->context.ContextFlags = CONTEXT_DEBUGGER_DR;

      /* Get current values of debug registers.  */
      CHECK (GetThreadContext (th->h, &th->context));

      DEBUG_EVENTS ("For 0x%x (once),  Dr6=0x%llx", th->tid, th->context.Dr6);

      /* Write debug registers back to thread, same values,
	 and re-read them.  */
      CHECK (SetThreadContext (th->h, &th->context));
      CHECK (GetThreadContext (th->h, &th->context));

      DEBUG_EVENTS ("For 0x%x (twice), Dr6=0x%llx", th->tid, th->context.Dr6);
    }

Which showed Dr6=0 after the write + re-read:

  [windows events] fill_thread_context: For 0x6a0 (once),  Dr6=0xffff0ff1
  [windows events] fill_thread_context: For 0x6a0 (twice), Dr6=0x0

This commit fixes the issue by detecting that a thread has a pending
watchpoint hit to report (Dr6 has interesting bits set), and if so,
avoid mofiying any debug register.  Instead, let the pending
watchpoint hit be reported by WaitForDebugEvent.  If infrun did want
to modify watchpoints, it will still be done when the thread is
eventually re-resumed after the pending watchpoint hit is reported.
(infrun knows how to gracefully handle the case of a watchpoint hit
for a watchpoint that has since been deleted.)

Change-Id: I21a3daa9e34eecfa054f0fea706e5ab40aabe70a
berenm pushed a commit that referenced this pull request Jun 1, 2024
[Changes from V1]
 - new testcase scfi-cfg-4.s for the changes in cmp_scfi_state.
 - new testcase ginsn-arith-1.s for ginsn creation for various add sub insns.
 - removed redundant insns from ginsn-misc-1.s, some of those insns are
   now in ginsn-arith-1.s.
[End of changes from V1]

Similar to the x86_64 testcases, some .s files contain the corresponding
CFI directives.  This helps in validating the synthesized CFI by running
those tests with and without the --scfi=experimental command line
option.

GAS issues some diagnostics, enabled by default, with
--scfi=experimental.  The diagnostics have been added with an intent to
help user correct inadvertent errors in their hand-written asm.  An
error is issued when GAS finds that input asm is not amenable to
accurate CFI synthesis.  The existing scfi-diag-*.s tests in the
gas/testsuite/gas/scfi/x86_64 directory test some SCFI diagnostics
already:

      - (#1) "Warning: SCFI: Asymetrical register restore"
      - (#2) "Error: SCFI: usage of REG_FP as scratch not supported"
      - (#3) "Error: SCFI: unsupported stack manipulation pattern"
      - (#4) "Error: untraceable control flow for func 'XXX'"

In the newly added aarch64 testsuite, further tests for additional
diagnostics have been added:
 - scfi-diag-1.s in this patch highlights an aarch64-specific diagnostic:
   (#5) "Warning: SCFI: ignored probable save/restore op with reg offset"

Additionally, some testcases are added to showcase the (currently)
unsupported patterns, e.g., scfi-unsupported-1.s
        mov     x16, 4384
        sub     sp, sp, x16

gas/testsuite/:
	* gas/scfi/README: Update comment to include aarch64.
	* gas/scfi/aarch64/scfi-aarch64.exp: New file.
	* gas/scfi/aarch64/ginsn-arith-1.l: New test.
	* gas/scfi/aarch64/ginsn-arith-1.s: New test.
	* gas/scfi/aarch64/ginsn-cofi-1.l: New test.
	* gas/scfi/aarch64/ginsn-cofi-1.s: New test.
	* gas/scfi/aarch64/ginsn-ldst-1.l: New test.
	* gas/scfi/aarch64/ginsn-ldst-1.s: New test.
	* gas/scfi/aarch64/scfi-cb-1.d: New test.
	* gas/scfi/aarch64/scfi-cb-1.l: New test.
	* gas/scfi/aarch64/scfi-cb-1.s: New test.
	* gas/scfi/aarch64/scfi-cfg-1.d: New test.
	* gas/scfi/aarch64/scfi-cfg-1.l: New test.
	* gas/scfi/aarch64/scfi-cfg-1.s: New test.
	* gas/scfi/aarch64/scfi-cfg-2.d: New test.
	* gas/scfi/aarch64/scfi-cfg-2.l: New test.
	* gas/scfi/aarch64/scfi-cfg-2.s: New test.
	* gas/scfi/aarch64/scfi-cfg-3.d: New test.
	* gas/scfi/aarch64/scfi-cfg-3.l: New test.
	* gas/scfi/aarch64/scfi-cfg-3.s: New test.
	* gas/scfi/aarch64/scfi-cfg-4.l: New test.
	* gas/scfi/aarch64/scfi-cfg-4.s: New test.
	* gas/scfi/aarch64/scfi-cond-br-1.d: New test.
	* gas/scfi/aarch64/scfi-cond-br-1.l: New test.
	* gas/scfi/aarch64/scfi-cond-br-1.s: New test.
	* gas/scfi/aarch64/scfi-diag-1.l: New test.
	* gas/scfi/aarch64/scfi-diag-1.s: New test.
	* gas/scfi/aarch64/scfi-diag-2.l: New test.
	* gas/scfi/aarch64/scfi-diag-2.s: New test.
	* gas/scfi/aarch64/scfi-ldrp-1.d: New test.
	* gas/scfi/aarch64/scfi-ldrp-1.l: New test.
	* gas/scfi/aarch64/scfi-ldrp-1.s: New test.
	* gas/scfi/aarch64/scfi-ldrp-2.d: New test.
	* gas/scfi/aarch64/scfi-ldrp-2.l: New test.
	* gas/scfi/aarch64/scfi-ldrp-2.s: New test.
	* gas/scfi/aarch64/scfi-strp-1.d: New test.
	* gas/scfi/aarch64/scfi-strp-1.l: New test.
	* gas/scfi/aarch64/scfi-strp-1.s: New test.
	* gas/scfi/aarch64/scfi-strp-2.d: New test.
	* gas/scfi/aarch64/scfi-strp-2.l: New test.
	* gas/scfi/aarch64/scfi-strp-2.s: New test.
	* gas/scfi/aarch64/scfi-unsupported-1.l: New test.
	* gas/scfi/aarch64/scfi-unsupported-1.s: New test.
berenm pushed a commit that referenced this pull request Jul 1, 2024
[Changes in V4]
 - New testcases for FP callee-saved registers.
   scfi-callee-saved-fp-1.s uses D registers, scfi-callee-saved-fp-2.s
   uses Q registers and is run with -mbig-endian.
 - Added new ops (movk, prfm) to ginsn-misc-1. These ops are not
   relevant for SCFI correctness; this testcase merely
   ensures graceful handling of ginsn creation for such insns.
 - Fixed ginsn-ldst-1 as it included some load / store ops with D
   registers, which we now handle.  Also added some insns using W and S
   registers.
 - Added a new test scfi-diag-3 where SCFI machinery reports the
   following error when it sees an SVE memory op with callee-saved
   register:
    "Error: SCFI: unhandled op 0xe5e0e000 may cause incorrect CFI"
[End of changes in V4]

[No changes in V3]

[Changes in V2]
 - new testcase scfi-cfg-4.s for the changes in cmp_scfi_state.
 - new testcase ginsn-arith-1.s for ginsn creation for various add sub insns.
 - removed redundant insns from ginsn-misc-1.s, some of those insns are
   now in ginsn-arith-1.s.
 - added more ld st opts in ginsn-ldst-1.s testcase.
[End of changes in V2]

Similar to the x86_64 testcases, some .s files contain the corresponding
CFI directives.  This helps in validating the synthesized CFI by running
those tests with and without the --scfi=experimental command line
option.

GAS issues some diagnostics, enabled by default, with
--scfi=experimental.  The diagnostics have been added with an intent to
help user correct inadvertent errors in their hand-written asm.  An
error is issued when GAS finds that input asm is not amenable to
accurate CFI synthesis.  The existing scfi-diag-*.s tests in the
gas/testsuite/gas/scfi/x86_64 directory test some SCFI diagnostics
already:

      - (#1) "Warning: SCFI: Asymetrical register restore"
      - (#2) "Error: SCFI: usage of REG_FP as scratch not supported"
      - (#3) "Error: SCFI: unsupported stack manipulation pattern"
      - (#4) "Error: untraceable control flow for func 'XXX'"

In the newly added aarch64 testsuite, further tests for additional
diagnostics have been added:
 - scfi-diag-1.s in this patch highlights an aarch64-specific diagnostic:
   (#5) "Warning: SCFI: ignored probable save/restore op with reg offset"

Additionally, some testcases are added to showcase the (currently)
unsupported patterns, e.g., scfi-unsupported-1.s
        mov     x16, 4384
        sub     sp, sp, x16

gas/testsuite/:
	* gas/scfi/README: Update comment to include aarch64.
	* gas/scfi/aarch64/scfi-aarch64.exp: New file.
	* gas/scfi/aarch64/ginsn-arith-1.l: New test.
	* gas/scfi/aarch64/ginsn-arith-1.s: New test.
	* gas/scfi/aarch64/ginsn-cofi-1.l: New test.
	* gas/scfi/aarch64/ginsn-cofi-1.s: New test.
	* gas/scfi/aarch64/ginsn-ldst-1.l: New test.
	* gas/scfi/aarch64/ginsn-ldst-1.s: New test.
	* gas/scfi/aarch64/scfi-callee-saved-fp-1.d: New test.
	* gas/scfi/aarch64/scfi-callee-saved-fp-1.l: New test.
	* gas/scfi/aarch64/scfi-callee-saved-fp-1.s: New test.
	* gas/scfi/aarch64/scfi-callee-saved-fp-2.d: New test.
	* gas/scfi/aarch64/scfi-callee-saved-fp-2.l: New test.
	* gas/scfi/aarch64/scfi-callee-saved-fp-2.s: New test.
	* gas/scfi/aarch64/scfi-cb-1.d: New test.
	* gas/scfi/aarch64/scfi-cb-1.l: New test.
	* gas/scfi/aarch64/scfi-cb-1.s: New test.
	* gas/scfi/aarch64/scfi-cfg-1.d: New test.
	* gas/scfi/aarch64/scfi-cfg-1.l: New test.
	* gas/scfi/aarch64/scfi-cfg-1.s: New test.
	* gas/scfi/aarch64/scfi-cfg-2.d: New test.
	* gas/scfi/aarch64/scfi-cfg-2.l: New test.
	* gas/scfi/aarch64/scfi-cfg-2.s: New test.
	* gas/scfi/aarch64/scfi-cfg-3.d: New test.
	* gas/scfi/aarch64/scfi-cfg-3.l: New test.
	* gas/scfi/aarch64/scfi-cfg-3.s: New test.
	* gas/scfi/aarch64/scfi-cfg-4.l: New test.
	* gas/scfi/aarch64/scfi-cfg-4.s: New test.
	* gas/scfi/aarch64/scfi-cond-br-1.d: New test.
	* gas/scfi/aarch64/scfi-cond-br-1.l: New test.
	* gas/scfi/aarch64/scfi-cond-br-1.s: New test.
	* gas/scfi/aarch64/scfi-diag-1.l: New test.
	* gas/scfi/aarch64/scfi-diag-1.s: New test.
	* gas/scfi/aarch64/scfi-diag-2.l: New test.
	* gas/scfi/aarch64/scfi-diag-2.s: New test.
	* gas/scfi/aarch64/scfi-diag-3.l: New test.
	* gas/scfi/aarch64/scfi-diag-3.s: New test.
	* gas/scfi/aarch64/scfi-ldrp-1.d: New test.
	* gas/scfi/aarch64/scfi-ldrp-1.l: New test.
	* gas/scfi/aarch64/scfi-ldrp-1.s: New test.
	* gas/scfi/aarch64/scfi-ldrp-2.d: New test.
	* gas/scfi/aarch64/scfi-ldrp-2.l: New test.
	* gas/scfi/aarch64/scfi-ldrp-2.s: New test.
	* gas/scfi/aarch64/scfi-strp-1.d: New test.
	* gas/scfi/aarch64/scfi-strp-1.l: New test.
	* gas/scfi/aarch64/scfi-strp-1.s: New test.
	* gas/scfi/aarch64/scfi-strp-2.d: New test.
	* gas/scfi/aarch64/scfi-strp-2.l: New test.
	* gas/scfi/aarch64/scfi-strp-2.s: New test.
	* gas/scfi/aarch64/scfi-unsupported-1.l: New test.
	* gas/scfi/aarch64/scfi-unsupported-1.s: New test.
berenm pushed a commit that referenced this pull request Jul 14, 2024
[Changes in V5]
 - Rename the previously added testcase scfi-diag-3 for SVE memory op to
   scfi-unsupported-2.  This will help keep track of the work to be done
   in near future.
 - Add new testcase scfi-diag-3 where the insn " b symbol+1" leads to an
   error:
      "Error: SCFI: 0x14000000 op with non-zero addend to sym not supported"
 - Add "stg sp, [sp, 32]!" and "ldpsw x8, x15, [sp, -256]" to ginsn-ldst-1.
 - Add prfm, irg, addg ops to ginsn-misc-1.
 - Add ldrsw, ldpsw ops to ginsn-misc-1.
 - Adjust ginsn-ldst-1 as now S and W register loads and stores are
   skipped.
 - Added a new testcase scfi-ldstnap-1 which includes some insns from
   iclass ldstnapair_offs.
[End of changes in V5]

[Changes in V4]
 - New testcases for FP callee-saved registers.
   scfi-callee-saved-fp-1.s uses D registers, scfi-callee-saved-fp-2.s
   uses Q registers and is run with -mbig-endian.
 - Added new ops (movk, prfm) to ginsn-misc-1. These ops are not
   relevant for SCFI correctness; this testcase merely
   ensures graceful handling of ginsn creation for such insns.
 - Fixed ginsn-ldst-1 as it included some load / store ops with D
   registers, which we now handle.  Also added some insns using W and S
   registers.
 - Added a new test scfi-diag-3 where SCFI machinery reports the
   following error when it sees an SVE memory op with callee-saved
   register:
    "Error: SCFI: unhandled op 0xe5e0e000 may cause incorrect CFI"
[End of changes in V4]

[No changes in V3]

[Changes in V2]
 - new testcase scfi-cfg-4.s for the changes in cmp_scfi_state.
 - new testcase ginsn-arith-1.s for ginsn creation for various add sub insns.
 - removed redundant insns from ginsn-misc-1.s, some of those insns are
   now in ginsn-arith-1.s.
 - added more ld st opts in ginsn-ldst-1.s testcase.
[End of changes in V2]

Similar to the x86_64 testcases, some .s files contain the corresponding
CFI directives.  This helps in validating the synthesized CFI by running
those tests with and without the --scfi=experimental command line
option.

GAS issues some diagnostics, enabled by default, with
--scfi=experimental.  The diagnostics have been added with an intent to
help user correct inadvertent errors in their hand-written asm.  An
error is issued when GAS finds that input asm is not amenable to
accurate CFI synthesis.  The existing scfi-diag-*.s tests in the
gas/testsuite/gas/scfi/x86_64 directory test some SCFI diagnostics
already:

      - (#1) "Warning: SCFI: Asymetrical register restore"
      - (#2) "Error: SCFI: usage of REG_FP as scratch not supported"
      - (#3) "Error: SCFI: unsupported stack manipulation pattern"
      - (#4) "Error: untraceable control flow for func 'XXX'"

In the newly added aarch64 testsuite, further tests for additional
diagnostics have been added:
 - scfi-diag-1.s in this patch highlights an aarch64-specific diagnostic:
   (#5) "Warning: SCFI: ignored probable save/restore op with reg offset"

Additionally, some testcases are added to showcase the (currently)
unsupported patterns, e.g., scfi-unsupported-1.s
        mov     x16, 4384
        sub     sp, sp, x16

gas/testsuite/:
	* gas/scfi/README: Update comment to include aarch64.
	* gas/scfi/aarch64/scfi-aarch64.exp: New file.
	* gas/scfi/aarch64/ginsn-arith-1.l: New test.
	* gas/scfi/aarch64/ginsn-arith-1.s: New test.
	* gas/scfi/aarch64/ginsn-cofi-1.l: New test.
	* gas/scfi/aarch64/ginsn-cofi-1.s: New test.
	* gas/scfi/aarch64/ginsn-ldst-1.l: New test.
	* gas/scfi/aarch64/ginsn-ldst-1.s: New test.
	* gas/scfi/aarch64/scfi-callee-saved-fp-1.d: New test.
	* gas/scfi/aarch64/scfi-callee-saved-fp-1.l: New test.
	* gas/scfi/aarch64/scfi-callee-saved-fp-1.s: New test.
	* gas/scfi/aarch64/scfi-callee-saved-fp-2.d: New test.
	* gas/scfi/aarch64/scfi-callee-saved-fp-2.l: New test.
	* gas/scfi/aarch64/scfi-callee-saved-fp-2.s: New test.
	* gas/scfi/aarch64/scfi-cb-1.d: New test.
	* gas/scfi/aarch64/scfi-cb-1.l: New test.
	* gas/scfi/aarch64/scfi-cb-1.s: New test.
	* gas/scfi/aarch64/scfi-cfg-1.d: New test.
	* gas/scfi/aarch64/scfi-cfg-1.l: New test.
	* gas/scfi/aarch64/scfi-cfg-1.s: New test.
	* gas/scfi/aarch64/scfi-cfg-2.d: New test.
	* gas/scfi/aarch64/scfi-cfg-2.l: New test.
	* gas/scfi/aarch64/scfi-cfg-2.s: New test.
	* gas/scfi/aarch64/scfi-cfg-3.d: New test.
	* gas/scfi/aarch64/scfi-cfg-3.l: New test.
	* gas/scfi/aarch64/scfi-cfg-3.s: New test.
	* gas/scfi/aarch64/scfi-cfg-4.l: New test.
	* gas/scfi/aarch64/scfi-cfg-4.s: New test.
	* gas/scfi/aarch64/scfi-cond-br-1.d: New test.
	* gas/scfi/aarch64/scfi-cond-br-1.l: New test.
	* gas/scfi/aarch64/scfi-cond-br-1.s: New test.
	* gas/scfi/aarch64/scfi-diag-1.l: New test.
	* gas/scfi/aarch64/scfi-diag-1.s: New test.
	* gas/scfi/aarch64/scfi-diag-2.l: New test.
	* gas/scfi/aarch64/scfi-diag-2.s: New test.
	* gas/scfi/aarch64/scfi-diag-3.l: New test.
	* gas/scfi/aarch64/scfi-diag-3.s: New test.
	* gas/scfi/aarch64/scfi-ldrp-1.d: New test.
	* gas/scfi/aarch64/scfi-ldrp-1.l: New test.
	* gas/scfi/aarch64/scfi-ldrp-1.s: New test.
	* gas/scfi/aarch64/scfi-ldrp-2.d: New test.
	* gas/scfi/aarch64/scfi-ldrp-2.l: New test.
	* gas/scfi/aarch64/scfi-ldrp-2.s: New test.
	* gas/scfi/aarch64/scfi-ldstnap-1.d: New test.
	* gas/scfi/aarch64/scfi-ldstnap-1.l: New test.
	* gas/scfi/aarch64/scfi-ldstnap-1.s: New test.
	* gas/scfi/aarch64/scfi-strp-1.d: New test.
	* gas/scfi/aarch64/scfi-strp-1.l: New test.
	* gas/scfi/aarch64/scfi-strp-1.s: New test.
	* gas/scfi/aarch64/scfi-strp-2.d: New test.
	* gas/scfi/aarch64/scfi-strp-2.l: New test.
	* gas/scfi/aarch64/scfi-strp-2.s: New test.
	* gas/scfi/aarch64/scfi-unsupported-1.l: New test.
	* gas/scfi/aarch64/scfi-unsupported-1.s: New test.
	* gas/scfi/aarch64/scfi-unsupported-2.l: New test.
	* gas/scfi/aarch64/scfi-unsupported-2.s: New test.
berenm pushed a commit that referenced this pull request Jul 19, 2024
Similar to the x86_64 testcases, some .s files contain the corresponding
CFI directives.  This helps in validating the synthesized CFI by running
those tests with and without the --scfi=experimental command line
option.

GAS issues some diagnostics, enabled by default, with
--scfi=experimental.  The diagnostics have been added with an intent to
help user correct inadvertent errors in their hand-written asm.  An
error is issued when GAS finds that input asm is not amenable to
accurate CFI synthesis.  The existing scfi-diag-*.s tests in the
gas/testsuite/gas/scfi/x86_64 directory test some SCFI diagnostics
already:

      - (#1) "Warning: SCFI: Asymetrical register restore"
      - (#2) "Error: SCFI: usage of REG_FP as scratch not supported"
      - (#3) "Error: SCFI: unsupported stack manipulation pattern"
      - (#4) "Error: untraceable control flow for func 'XXX'"

In the newly added aarch64 testsuite, further tests for additional
diagnostics have been added:
 - scfi-diag-1.s in this patch highlights an aarch64-specific diagnostic:
   (#5) "Warning: SCFI: ignored probable save/restore op with reg offset"

Additionally, some testcases are added to showcase the (currently)
unsupported patterns, e.g., scfi-unsupported-1.s
        mov     x16, 4384
        sub     sp, sp, x16

gas/testsuite/:
	* gas/scfi/README: Update comment to include aarch64.
	* gas/scfi/aarch64/scfi-aarch64.exp: New file.
	* gas/scfi/aarch64/ginsn-arith-1.l: New test.
	* gas/scfi/aarch64/ginsn-arith-1.s: New test.
	* gas/scfi/aarch64/ginsn-cofi-1.l: New test.
	* gas/scfi/aarch64/ginsn-cofi-1.s: New test.
	* gas/scfi/aarch64/ginsn-ldst-1.l: New test.
	* gas/scfi/aarch64/ginsn-ldst-1.s: New test.
	* gas/scfi/aarch64/scfi-callee-saved-fp-1.d: New test.
	* gas/scfi/aarch64/scfi-callee-saved-fp-1.l: New test.
	* gas/scfi/aarch64/scfi-callee-saved-fp-1.s: New test.
	* gas/scfi/aarch64/scfi-callee-saved-fp-2.d: New test.
	* gas/scfi/aarch64/scfi-callee-saved-fp-2.l: New test.
	* gas/scfi/aarch64/scfi-callee-saved-fp-2.s: New test.
	* gas/scfi/aarch64/scfi-cb-1.d: New test.
	* gas/scfi/aarch64/scfi-cb-1.l: New test.
	* gas/scfi/aarch64/scfi-cb-1.s: New test.
	* gas/scfi/aarch64/scfi-cfg-1.d: New test.
	* gas/scfi/aarch64/scfi-cfg-1.l: New test.
	* gas/scfi/aarch64/scfi-cfg-1.s: New test.
	* gas/scfi/aarch64/scfi-cfg-2.d: New test.
	* gas/scfi/aarch64/scfi-cfg-2.l: New test.
	* gas/scfi/aarch64/scfi-cfg-2.s: New test.
	* gas/scfi/aarch64/scfi-cfg-3.d: New test.
	* gas/scfi/aarch64/scfi-cfg-3.l: New test.
	* gas/scfi/aarch64/scfi-cfg-3.s: New test.
	* gas/scfi/aarch64/scfi-cfg-4.l: New test.
	* gas/scfi/aarch64/scfi-cfg-4.s: New test.
	* gas/scfi/aarch64/scfi-cond-br-1.d: New test.
	* gas/scfi/aarch64/scfi-cond-br-1.l: New test.
	* gas/scfi/aarch64/scfi-cond-br-1.s: New test.
	* gas/scfi/aarch64/scfi-diag-1.l: New test.
	* gas/scfi/aarch64/scfi-diag-1.s: New test.
	* gas/scfi/aarch64/scfi-diag-2.l: New test.
	* gas/scfi/aarch64/scfi-diag-2.s: New test.
	* gas/scfi/aarch64/scfi-diag-3.l: New test.
	* gas/scfi/aarch64/scfi-diag-3.s: New test.
	* gas/scfi/aarch64/scfi-ldrp-1.d: New test.
	* gas/scfi/aarch64/scfi-ldrp-1.l: New test.
	* gas/scfi/aarch64/scfi-ldrp-1.s: New test.
	* gas/scfi/aarch64/scfi-ldrp-2.d: New test.
	* gas/scfi/aarch64/scfi-ldrp-2.l: New test.
	* gas/scfi/aarch64/scfi-ldrp-2.s: New test.
	* gas/scfi/aarch64/scfi-ldstnap-1.d: New test.
	* gas/scfi/aarch64/scfi-ldstnap-1.l: New test.
	* gas/scfi/aarch64/scfi-ldstnap-1.s: New test.
	* gas/scfi/aarch64/scfi-strp-1.d: New test.
	* gas/scfi/aarch64/scfi-strp-1.l: New test.
	* gas/scfi/aarch64/scfi-strp-1.s: New test.
	* gas/scfi/aarch64/scfi-strp-2.d: New test.
	* gas/scfi/aarch64/scfi-strp-2.l: New test.
	* gas/scfi/aarch64/scfi-strp-2.s: New test.
	* gas/scfi/aarch64/scfi-unsupported-1.l: New test.
	* gas/scfi/aarch64/scfi-unsupported-1.s: New test.
	* gas/scfi/aarch64/scfi-unsupported-2.l: New test.
	* gas/scfi/aarch64/scfi-unsupported-2.s: New test.
berenm pushed a commit that referenced this pull request Jul 31, 2024
Since commit b1da98a ("gdb: remove use of alloca in
new_macro_definition"), if cached_argv is empty, we call macro_bcache
with a nullptr data.  This ends up caught by UBSan deep down in the
bcache code:

    $ ./gdb -nx -q --data-directory=data-directory  /home/smarchi/build/binutils-gdb/gdb/testsuite/outputs/gdb.base/macscp/macscp -readnow
    Reading symbols from /home/smarchi/build/binutils-gdb/gdb/testsuite/outputs/gdb.base/macscp/macscp...
    Expanding full symbols from /home/smarchi/build/binutils-gdb/gdb/testsuite/outputs/gdb.base/macscp/macscp...
    /home/smarchi/src/binutils-gdb/gdb/bcache.c:195:12: runtime error: null pointer passed as argument 2, which is declared to never be null

The backtrace:

    #1  0x00007ffff619a05d in __ubsan::__ubsan_handle_nonnull_arg_abort (Data=<optimized out>) at ../../../../src/libsanitizer/ubsan/ubsan_handlers.cpp:750
    #2  0x000055556337fba2 in gdb::bcache::insert (this=0x62d0000c8458, addr=0x0, length=0, added=0x0) at /home/smarchi/src/binutils-gdb/gdb/bcache.c:195
    #3  0x0000555564b49222 in gdb::bcache::insert<char const*, void> (this=0x62d0000c8458, addr=0x0, length=0, added=0x0) at /home/smarchi/src/binutils-gdb/gdb/bcache.h:158
    #4  0x0000555564b481fa in macro_bcache<char const*> (t=0x62100007ae70, addr=0x0, len=0) at /home/smarchi/src/binutils-gdb/gdb/macrotab.c:117
    #5  0x0000555564b42b4a in new_macro_definition (t=0x62100007ae70, kind=macro_function_like, special_kind=macro_ordinary, argv=std::__debug::vector of length 0, capacity 0, replacement=0x62a00003af3a "__builtin_va_arg_pack ()") at /home/smarchi/src/binutils-gdb/gdb/macrotab.c:573
    #6  0x0000555564b44674 in macro_define_internal (source=0x6210000ab9e0, line=469, name=0x7fffffffa710 "__va_arg_pack", kind=macro_function_like, special_kind=macro_ordinary, argv=std::__debug::vector of length 0, capacity 0, replacement=0x62a00003af3a "__builtin_va_arg_pack ()") at /home/smarchi/src/binutils-gdb/gdb/macrotab.c:777
    #7  0x0000555564b44ae2 in macro_define_function (source=0x6210000ab9e0, line=469, name=0x7fffffffa710 "__va_arg_pack", argv=std::__debug::vector of length 0, capacity 0, replacement=0x62a00003af3a "__builtin_va_arg_pack ()") at /home/smarchi/src/binutils-gdb/gdb/macrotab.c:816
    #8  0x0000555563f62fc8 in parse_macro_definition (file=0x6210000ab9e0, line=469, body=0x62a00003af2a "__va_arg_pack() __builtin_va_arg_pack ()") at /home/smarchi/src/binutils-gdb/gdb/dwarf2/macro.c:203

This can be reproduced by running gdb.base/macscp.exp.  Avoid calling
macro_bcache if the macro doesn't have any arguments.

Change-Id: I33b5a7c3b3a93d5adba98983fcaae9c8522c383d
berenm pushed a commit that referenced this pull request Sep 9, 2024
The commit:

  commit c6b4867
  Date:   Thu Mar 30 19:21:22 2023 +0100

      gdb: parse pending breakpoint thread/task immediately

Introduce a use bug where the value of a temporary variable was being
used after it had gone out of scope.  This was picked up by the
address sanitizer and would result in this error:

  (gdb) maintenance selftest create_breakpoint_parse_arg_string
  Running selftest create_breakpoint_parse_arg_string.
  =================================================================
  ==2265825==ERROR: AddressSanitizer: stack-use-after-scope on address 0x7fbb08046511 at pc 0x000001632230 bp 0x7fff7c2fb770 sp 0x7fff7c2fb768
  READ of size 1 at 0x7fbb08046511 thread T0
      #0 0x163222f in create_breakpoint_parse_arg_string(char const*, std::unique_ptr<char, gdb::xfree_deleter<char> >*, int*, int*, int*, std::unique_ptr<char, gdb::xfree_deleter<char> >*, bool*) ../../src/gdb/break-cond-parse.c:496
      #1 0x1633026 in test ../../src/gdb/break-cond-parse.c:582
      #2 0x163391b in create_breakpoint_parse_arg_string_tests ../../src/gdb/break-cond-parse.c:649
      #3 0x12cfebc in void std::__invoke_impl<void, void (*&)()>(std::__invoke_other, void (*&)()) /usr/include/c++/13/bits/invoke.h:61
      #4 0x12cc8ee in std::enable_if<is_invocable_r_v<void, void (*&)()>, void>::type std::__invoke_r<void, void (*&)()>(void (*&)()) /usr/include/c++/13/bits/invoke.h:111
      #5 0x12c81e5 in std::_Function_handler<void (), void (*)()>::_M_invoke(std::_Any_data const&) /usr/include/c++/13/bits/std_function.h:290
      #6 0x18bb51d in std::function<void ()>::operator()() const /usr/include/c++/13/bits/std_function.h:591
      #7 0x4193ef9 in selftests::run_tests(gdb::array_view<char const* const>, bool) ../../src/gdbsupport/selftest.cc:100
      #8 0x21c2206 in maintenance_selftest ../../src/gdb/maint.c:1172
      ... etc ...

The problem was caused by three lines like this one:

  thread_info *thr
    = parse_thread_id (std::string (t.get_value ()).c_str (), &tmptok);

After parsing the thread-id TMPTOK would be left pointing into the
temporary string which had been created on this line.  When on the
next line we did this:

  gdb_assert (*tmptok == '\0');

The value of *TMPTOK is undefined.

Fix this by creating the std::string earlier in the scope.  Now the
contents of the string will remain valid when we check *TMPTOK.  The
address sanitizer issue is now resolved.
berenm pushed a commit that referenced this pull request Sep 13, 2024
The binary provided with bug 32165 [1] has 36139 ELF sections.  GDB
crashes on it with (note that my GDB is build with -D_GLIBCXX_DEBUG=1:

    $ ./gdb  -nx -q --data-directory=data-directory ./vmlinux
    Reading symbols from ./vmlinux...
    (No debugging symbols found in ./vmlinux)
    (gdb) info func
    /usr/include/c++/14.2.1/debug/vector:508:
    In function:
        std::debug::vector<_Tp, _Allocator>::reference std::debug::vector<_Tp,
        _Allocator>::operator[](size_type) [with _Tp = long unsigned int;
        _Allocator = std::allocator<long unsigned int>; reference = long
        unsigned int&; size_type = long unsigned int]

    Error: attempt to subscript container with out-of-bounds index -29445, but
    container only holds 36110 elements.

    Objects involved in the operation:
        sequence "this" @ 0x514000007340 {
          type = std::debug::vector<unsigned long, std::allocator<unsigned long> >;
        }

The crash occurs here:

    #3  0x00007ffff5e334c3 in __GI_abort () at abort.c:79
    #4  0x00007ffff689afc4 in __gnu_debug::_Error_formatter::_M_error (this=<optimized out>) at /usr/src/debug/gcc/gcc/libstdc++-v3/src/c++11/debug.cc:1320
    #5  0x0000555561119a16 in std::__debug::vector<unsigned long, std::allocator<unsigned long> >::operator[] (this=0x514000007340, __n=18446744073709522171)
        at /usr/include/c++/14.2.1/debug/vector:508
    #6  0x0000555562e288e8 in minimal_symbol::value_address (this=0x5190000bb698, objfile=0x514000007240) at /home/smarchi/src/binutils-gdb/gdb/symtab.c:517
    #7  0x0000555562e5a131 in global_symbol_searcher::expand_symtabs (this=0x7ffff0f5c340, objfile=0x514000007240, preg=std::optional [no contained value])
        at /home/smarchi/src/binutils-gdb/gdb/symtab.c:4983
    #8  0x0000555562e5d2ed in global_symbol_searcher::search (this=0x7ffff0f5c340) at /home/smarchi/src/binutils-gdb/gdb/symtab.c:5189
    #9  0x0000555562e5ffa4 in symtab_symbol_info (quiet=false, exclude_minsyms=false, regexp=0x0, kind=FUNCTION_DOMAIN, t_regexp=0x0, from_tty=1)
        at /home/smarchi/src/binutils-gdb/gdb/symtab.c:5361
    #10 0x0000555562e6131b in info_functions_command (args=0x0, from_tty=1) at /home/smarchi/src/binutils-gdb/gdb/symtab.c:5525

That is, at this line of `minimal_symbol::value_address`, where
`objfile->section_offsets` is an `std::vector`:

    return (CORE_ADDR (this->unrelocated_address ())
	    + objfile->section_offsets[this->section_index ()]);

A section index of -29445 is suspicious.  The minimal_symbol at play
here is:

    (top-gdb) p m_name
    $1 = 0x521001de10af "_sinittext"

So I restarted debugging, breaking on:

   (top-gdb) b general_symbol_info::set_section_index if $_streq("_sinittext", m_name)

And I see that weird -29445 value:

    (top-gdb) frame
    #0  general_symbol_info::set_section_index (this=0x525000082390, idx=-29445) at /home/smarchi/src/binutils-gdb/gdb/symtab.h:611
    611       { m_section = idx; }

But going up one frame, the section index is 36091:

    (top-gdb) frame
    #1  0x0000555562426526 in minimal_symbol_reader::record_full (this=0x7ffff0ead560, name="_sinittext", copy_name=false,
        address=-2111475712, ms_type=mst_text, section=36091) at /home/smarchi/src/binutils-gdb/gdb/minsyms.c:1228
    1228      msymbol->set_section_index (section);

It seems like the problem is just that the type used for the section
index (short) is not big enough.  Change from short to int.  If somebody
insists, we could even go long long / int64_t, but I doubt it's
necessary.

With that fixed, I get:

    (gdb) info func
    All defined functions:

    Non-debugging symbols:
    0xffffffff81000000  _stext
    0xffffffff82257000  _sinittext
    0xffffffff822b4ebb  _einittext

[1] https://sourceware.org/bugzilla/show_bug.cgi?id=32165

Change-Id: Icb1c3de9474ff5adef7e0bbbf5e0b67b279dee04
Reviewed-By: Tom de Vries <tdevries@suse.de>
Reviewed-by: Keith Seitz <keiths@redhat.com>
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