[gdb/symtab] Fix zero address complaint for shlib

In PR28004 the following warning / Internal error is reported: ... $ gdb -q -batch \ -iex "set sysroot $(pwd -P)/repro" \ ./repro/gdb \ ./repro/core \ -ex bt ... Program terminated with signal SIGABRT, Aborted. #0 0x00007ff8fe8e5d22 in raise () from repro/usr/lib/libc.so.6 [Current thread is 1 (LWP 1762498)] #1 0x00007ff8fe8cf862 in abort () from repro/usr/lib/libc.so.6 warning: (Internal error: pc 0x7ff8feb2c21d in read in psymtab, \ but not in symtab.) warning: (Internal error: pc 0x7ff8feb2c218 in read in psymtab, \ but not in symtab.) ... #2 0x00007ff8feb2c21e in __gnu_debug::_Error_formatter::_M_error() const \ [clone .cold] (warning: (Internal error: pc 0x7ff8feb2c21d in read in \ psymtab, but not in symtab.) ) from repro/usr/lib/libstdc++.so.6 ... The warning is about the following: - in find_pc_sect_compunit_symtab we try to find the address (0x7ff8feb2c218 / 0x7ff8feb2c21d) in the symtabs. - that fails, so we try again in the partial symtabs. - we find a matching partial symtab - however, the partial symtab has a full symtab, so we should have found a matching symtab in the first step. The addresses are: ... (gdb) info sym 0x7ff8feb2c218 __gnu_debug::_Error_formatter::_M_error() const [clone .cold] in \ section .text of repro/usr/lib/libstdc++.so.6 (gdb) info sym 0x7ff8feb2c21d __gnu_debug::_Error_formatter::_M_error() const [clone .cold] + 5 in \ section .text of repro/usr/lib/libstdc++.so.6 ... which correspond to unrelocated addresses 0x9c218 and 0x9c21d: ... $ nm -C repro/usr/lib/libstdc++.so.6.0.29 | grep 000000000009c218 000000000009c218 t __gnu_debug::_Error_formatter::_M_error() const \ [clone .cold] ... which belong to function __gnu_debug::_Error_formatter::_M_error() in /build/gcc/src/gcc/libstdc++-v3/src/c++11/debug.cc. The partial symtab that is found for the addresses is instead the one for /build/gcc/src/gcc/libstdc++-v3/src/c++98/bitmap_allocator.cc, which is incorrect. This happens as follows. The bitmap_allocator.cc CU has DW_AT_ranges at .debug_rnglist offset 0x4b50: ... 00004b50 0000000000000000 0000000000000056 00004b5a 00000000000a4790 00000000000a479c 00004b64 00000000000a47a0 00000000000a47ac ... When reading the first range 0x0..0x56, it doesn't trigger the "start address of zero" complaint here: ... /* A not-uncommon case of bad debug info. Don't pollute the addrmap with bad data. */ if (range_beginning + baseaddr == 0 && !per_objfile->per_bfd->has_section_at_zero) { complaint (_(".debug_rnglists entry has start address of zero" " [in module %s]"), objfile_name (objfile)); continue; } ... because baseaddr != 0, which seems incorrect given that when loading the shared library individually in gdb (and consequently baseaddr == 0), we do see the complaint. Consequently, we run into this case in dwarf2_get_pc_bounds: ... if (low == 0 && !per_objfile->per_bfd->has_section_at_zero) return PC_BOUNDS_INVALID; ... which then results in this code in process_psymtab_comp_unit_reader being called with cu_bounds_kind == PC_BOUNDS_INVALID, which sets the set_addrmap argument to 1: ... scan_partial_symbols (first_die, &lowpc, &highpc, cu_bounds_kind <= PC_BOUNDS_INVALID, cu); ... and consequently, the CU addrmap gets build using address info from the functions. During that process, addrmap_set_empty is called with a range that includes 0x9c218 and 0x9c21d: ... (gdb) p /x start $7 = 0x9989c (gdb) p /x end_inclusive $8 = 0xb200d ... but it's called for a function at DIE 0x54153 with DW_AT_ranges at 0x40ae: ... 000040ae 00000000000b1ee0 00000000000b200e 000040b9 000000000009989c 00000000000998c4 000040c3 <End of list> ... and neither range includes 0x9c218 and 0x9c21d. This is caused by this code in partial_die_info::read: ... if (dwarf2_ranges_read (ranges_offset, &lowpc, &highpc, cu, nullptr, tag)) has_pc_info = 1; ... which pretends that the function is located at addresses 0x9989c..0xb200d, which is indeed not the case. This patch fixes the first problem encountered: fix the "start address of zero" complaint warning by removing the baseaddr part from the condition. Same for dwarf2_ranges_process. The effect is that: - the complaint is triggered, and - the warning / Internal error is no longer triggered. This does not fix the observed problem in partial_die_info::read, which is filed as PR28200. Tested on x86_64-linux. Co-Authored-By: Simon Marchi <simon.marchi@polymtl.ca> gdb/ChangeLog: 2021-08-06 Simon Marchi <simon.marchi@polymtl.ca> Tom de Vries <tdevries@suse.de> PR symtab/28004 * dwarf2/read.c (dwarf2_rnglists_process, dwarf2_ranges_process): Fix zero address complaint. gdb/testsuite/ChangeLog: 2021-08-06 Simon Marchi <simon.marchi@polymtl.ca> Tom de Vries <tdevries@suse.de> PR symtab/28004 * gdb.dwarf2/dw2-zero-range-shlib.c: New test. * gdb.dwarf2/dw2-zero-range.c: New test. * gdb.dwarf2/dw2-zero-range.exp: New file.
devkitPro · Aug 6, 2021 · a656ee0 · a656ee0
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commit a656ee0
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diff --git a/gdb/ChangeLog b/gdb/ChangeLog
@@ -1,3 +1,10 @@
+2021-08-06  Simon Marchi  <simon.marchi@polymtl.ca>
+	    Tom de Vries  <tdevries@suse.de>
+
+	PR symtab/28004
+	* dwarf2/read.c (dwarf2_rnglists_process, dwarf2_ranges_process):
+	Fix zero address complaint.
+
 2021-08-02  Tom Tromey  <tromey@adacore.com>
 
 	PR varobj/28131

diff --git a/gdb/dwarf2/read.c b/gdb/dwarf2/read.c
@@ -13608,7 +13608,6 @@ dwarf2_rnglists_process (unsigned offset, struct dwarf2_cu *cu,
   /* Base address selection entry.  */
   gdb::optional<CORE_ADDR> base;
   const gdb_byte *buffer;
-  CORE_ADDR baseaddr;
   bool overflow = false;
   ULONGEST addr_index;
   struct dwarf2_section_info *rnglists_section;
@@ -13625,8 +13624,6 @@ dwarf2_rnglists_process (unsigned offset, struct dwarf2_cu *cu,
     }
   buffer = rnglists_section->buffer + offset;
 
-  baseaddr = objfile->text_section_offset ();
-
   while (1)
     {
       /* Initialize it due to a false compiler warning.  */
@@ -13768,7 +13765,7 @@ dwarf2_rnglists_process (unsigned offset, struct dwarf2_cu *cu,
 
       /* A not-uncommon case of bad debug info.
 	 Don't pollute the addrmap with bad data.  */
-      if (range_beginning + baseaddr == 0
+      if (range_beginning == 0
 	  && !per_objfile->per_bfd->has_section_at_zero)
 	{
 	  complaint (_(".debug_rnglists entry has start address of zero"
@@ -13810,7 +13807,6 @@ dwarf2_ranges_process (unsigned offset, struct dwarf2_cu *cu, dwarf_tag tag,
   gdb::optional<CORE_ADDR> base;
   unsigned int dummy;
   const gdb_byte *buffer;
-  CORE_ADDR baseaddr;
 
   if (cu_header->version >= 5)
     return dwarf2_rnglists_process (offset, cu, tag, callback);
@@ -13826,8 +13822,6 @@ dwarf2_ranges_process (unsigned offset, struct dwarf2_cu *cu, dwarf_tag tag,
     }
   buffer = per_objfile->per_bfd->ranges.buffer + offset;
 
-  baseaddr = objfile->text_section_offset ();
-
   while (1)
     {
       CORE_ADDR range_beginning, range_end;
@@ -13878,7 +13872,7 @@ dwarf2_ranges_process (unsigned offset, struct dwarf2_cu *cu, dwarf_tag tag,
 
       /* A not-uncommon case of bad debug info.
 	 Don't pollute the addrmap with bad data.  */
-      if (range_beginning + baseaddr == 0
+      if (range_beginning == 0
 	  && !per_objfile->per_bfd->has_section_at_zero)
 	{
 	  complaint (_(".debug_ranges entry has start address of zero"

diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
@@ -1,3 +1,11 @@
+2021-08-06  Simon Marchi  <simon.marchi@polymtl.ca>
+	    Tom de Vries  <tdevries@suse.de>
+
+	PR symtab/28004
+	* gdb.dwarf2/dw2-zero-range-shlib.c: New test.
+	* gdb.dwarf2/dw2-zero-range.c: New test.
+	* gdb.dwarf2/dw2-zero-range.exp: New file.
+
 2021-08-02  Tom Tromey  <tromey@adacore.com>
 
 	PR varobj/28131

diff --git a/gdb/testsuite/gdb.dwarf2/dw2-zero-range-shlib.c b/gdb/testsuite/gdb.dwarf2/dw2-zero-range-shlib.c
@@ -0,0 +1,21 @@
+/*
+   Copyright 2021 Free Software Foundation, Inc.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+void
+foo (void)
+{
+  asm ("foo_label: .globl foo_label");
+}
diff --git a/gdb/testsuite/gdb.dwarf2/dw2-zero-range.c b/gdb/testsuite/gdb.dwarf2/dw2-zero-range.c
@@ -0,0 +1,24 @@
+/*
+   Copyright 2021 Free Software Foundation, Inc.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+extern void foo (void);
+
+int
+main (void)
+{
+  asm ("main_label: .globl main_label");
+  foo ();
+}
diff --git a/gdb/testsuite/gdb.dwarf2/dw2-zero-range.exp b/gdb/testsuite/gdb.dwarf2/dw2-zero-range.exp
@@ -0,0 +1,185 @@
+# Copyright 2021 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+# Check that the ".debug_ranges entry has start address of zero" complaint
+# is triggered for a loaded shared lib.
+
+load_lib dwarf.exp
+
+# This test can only be run on targets which support DWARF-2 and use gas.
+if {![dwarf2_support]} {
+    verbose "Skipping $gdb_test_file_name."
+    return 0
+}
+
+if {[skip_shlib_tests]} {
+    return 0
+}
+
+standard_testfile .c -shlib.c -dw.S
+
+# Test with both a .debug_ranges section (DWARF 4) and a .debug_rnglists
+# section (DWARF 5).
+
+foreach_with_prefix ranges_sect {ranges rnglists} {
+    set asm_file [standard_output_file ${ranges_sect}-$srcfile3]
+
+    if { $ranges_sect == "ranges" } {
+	Dwarf::assemble $asm_file {
+	    global srcdir subdir srcfile2
+	    declare_labels ranges_label
+
+	    cu {} {
+		compile_unit {
+		    {language @DW_LANG_C}
+		    {name $srcfile2}
+		    {ranges ${ranges_label} DW_FORM_sec_offset}
+		} {
+		    subprogram {
+			{external 1 flag}
+			{name foo}
+		    }
+		}
+	    }
+
+	    ranges {is_64 [is_64_target]} {
+		ranges_label: sequence {
+		    base 0
+		    range 0 1
+		}
+	    }
+	}
+    } elseif { $ranges_sect == "rnglists" } {
+	Dwarf::assemble $asm_file {
+	    global srcdir subdir srcfile2
+	    declare_labels rnglists_label
+
+	    cu {
+		version 5
+	    } {
+		compile_unit {
+		    {language @DW_LANG_C}
+		    {name $srcfile2}
+		    {ranges ${rnglists_label} DW_FORM_sec_offset}
+		} {
+		    subprogram {
+			{external 1 flag}
+			{name foo}
+		    }
+		}
+	    }
+
+	    rnglists {
+		table {
+		    rnglists_label: list_ {
+			start_end 0 1
+		    }
+		}
+	    }
+	}
+    } else {
+	error "invalid ranges section kind"
+    }
+
+    set lib1 [standard_output_file shr1.sl]
+    set lib_opts "nodebug"
+
+    set sources [list ${srcdir}/${subdir}/$srcfile2 $asm_file]
+    if { [gdb_compile_shlib $sources ${lib1} $lib_opts] != "" } {
+	untested "failed to compile"
+	return -1
+    }
+
+    set exec_opts [list debug shlib=${lib1}]
+    set sources ${srcdir}/${subdir}/${srcfile}
+    if { [gdb_compile $sources  ${binfile} executable \
+	      $exec_opts] != ""} {
+	untested "failed to compile"
+	return -1
+    }
+
+    clean_restart $binfile
+
+    set readnow_p [readnow]
+
+    # Don't load the symbols for $lib1 during runto_main.
+    # Instead, we do this afterwards using "sharedlibrary $lib1".
+    gdb_test_no_output "set auto-solib-add off"
+
+    if { ![runto_main] } {
+	fail "cannot run to main."
+	return -1
+    }
+
+    set complaint_re ".debug_${ranges_sect} entry has start address of zero"
+    set re \
+	"During symbol reading: $complaint_re \\\[in module \[^\r\n\]*\\\]"
+
+    # Test for presence of complaint, with lib1 relocated.
+    with_complaints 1 {
+	set test "Zero address complaint - relocated - psymtab"
+	set have_complaint 0
+	gdb_test_multiple "sharedlibrary $lib1" $test {
+	    -re -wrap $re {
+		set have_complaint 1
+	    }
+	    -re -wrap "" {
+	    }
+	}
+
+	if { $have_complaint } {
+	    pass $test
+	} else {
+	    set index [have_index $lib1]
+	    if { $index == "gdb_index" } {
+		kfail symtab/28159 $test
+	    } else {
+		fail $test
+	    }
+	}
+    }
+
+    if { ! $readnow_p } {
+	with_complaints 1 {
+	    gdb_test "maint expand-symtabs $srcfile2" $re \
+		"Zero address complaint - relocated - symtab"
+	}
+    }
+
+    clean_restart
+    # Test for presence of complaint, with lib1 unrelocated.
+    with_complaints 1 {
+	gdb_load $lib1
+	set test "Zero address complaint - unrelocated - psymtab"
+	set have_complaint [regexp $re.* $gdb_file_cmd_msg]
+	if { $have_complaint } {
+	    pass $test
+	} else {
+	    set index [have_index $lib1]
+	    if { $index == "gdb_index" } {
+		kfail symtab/28159 $test
+	    } else {
+		fail $test
+	    }
+	}
+    }
+
+    if { ! $readnow_p } {
+	with_complaints 1 {
+	    gdb_test "maint expand-symtabs $srcfile2" $re \
+		"Zero address complaint - unrelocated - symtab"
+	}
+    }
+}