🐛 fix another C-ISA loophole (#806)

CHANGELOG.md

@@ -30,11 +30,12 @@ mimpid = 0x01040312 -> Version 01.04.03.12 -> v1.4.3.12
 
 | Date | Version | Comment | Link |
 |:----:|:-------:|:--------|:----:|
+| 14.02.2024 | 1.9.4.12 | :bug: close another illegal compressed instruction encoding loophole | [#806](https://github.com/stnolting/neorv32/pull/806) |
 | 11.02.2024 | 1.9.4.11 | :bug: fix several FPU bugs and design flaws | [#794](https://github.com/stnolting/neorv32/pull/794) |
 | 11.02.2024 | 1.9.4.10 | minor additions to previous version (1.9.4.9): fix HPM configuration read-back | [#804](https://github.com/stnolting/neorv32/pull/804) |
 | 10.02.2024 | 1.9.4.9 | fixing HPM configuration's null range assertions | [#803](https://github.com/stnolting/neorv32/pull/803) |
 | 10.02.2024 | 1.9.4.8 | :bug: fix missing fence pass-through in caches | [#802](https://github.com/stnolting/neorv32/pull/802) |
-| 09.02.2024 | 1.9.4.7 | :warning: integrate fence signal into CPU bus, remove top entity's fence signals | (#800)[https://github.com/stnolting/neorv32/pull/800] |
+| 09.02.2024 | 1.9.4.7 | :warning: integrate fence signal into CPU bus, remove top entity's fence signals | [#800](https://github.com/stnolting/neorv32/pull/800) |
 | 09.02.2024 | 1.9.4.6 | :sparkles: add configurable XIP cache | [#799](https://github.com/stnolting/neorv32/pull/799) |
 | 09.02.2024 | 1.9.4.5 | :bug: close further illegal compressed instruction encoding loopholes | [#797](https://github.com/stnolting/neorv32/pull/797) |
 | 04.02.2024 | 1.9.4.4 | :bug: fix minor bug: CPU instruction bus privilege signal did not remain stable during the entire request | [#792](https://github.com/stnolting/neorv32/pull/792) |

rtl/core/neorv32_cpu_decompressor.vhd

@@ -288,7 +288,7 @@ begin
                 decoded(instr_imm12_lsb_c + 2)                        <= ci_instr16_i(4);
                 decoded(instr_imm12_lsb_c + 3)                        <= ci_instr16_i(5);
                 decoded(instr_imm12_lsb_c + 4)                        <= ci_instr16_i(6);
-                if ((ci_instr16_i(12) or or_reduce_f(ci_instr16_i(6 downto 2))) = '0') then -- nzuimm = 0 -> RV32 custom / illegal
+                if (ci_instr16_i(12) = '1') then -- nzuimm[5] = 1 -> RV32 custom / illegal
                   illegal <= '1';
                 end if;
               when "10" => -- C.ANDI

rtl/core/neorv32_package.vhd

@@ -53,7 +53,7 @@ package neorv32_package is
 
   -- Architecture Constants -----------------------------------------------------------------
   -- -------------------------------------------------------------------------------------------
-  constant hw_version_c : std_ulogic_vector(31 downto 0) := x"01090411"; -- hardware version
+  constant hw_version_c : std_ulogic_vector(31 downto 0) := x"01090412"; -- hardware version
   constant archid_c     : natural := 19; -- official RISC-V architecture ID
   constant XLEN         : natural := 32; -- native data path width