From 41ff9aa49f6c54c66d0e6b37f265fd9cb0176057 Mon Sep 17 00:00:00 2001 From: Paul Floyd Date: Sun, 17 Dec 2023 14:18:51 +0100 Subject: [PATCH 4/4] Bug 478624 - Valgrind incompatibility with binutils-2.42 on x86 with new nop patterns (unhandled instruction bytes: 0x2E 0x8D 0xB4 0x26) It was a bit of a struggle to get the testcase to build with both clang and gcc (oddly enough gcc was more difficult) so I just resorted to using .byte arrays. (cherry picked from commit d35005cef8ad8207542738812705ceabf137d7e0) Upstream-Status: Backport [https://sourceware.org/git/?p=valgrind.git;a=commit;h=41ff9aa49f6c54c66d0e6b37f265fd9cb0176057] Signed-off-by: Khem Raj --- .gitignore | 1 + NEWS | 2 ++ VEX/priv/guest_x86_toIR.c | 22 +++++++++++++- none/tests/x86/Makefile.am | 2 ++ none/tests/x86/gnu_binutils_nop.c | 34 ++++++++++++++++++++++ none/tests/x86/gnu_binutils_nop.stderr.exp | 0 none/tests/x86/gnu_binutils_nop.vgtest | 2 ++ 7 files changed, 62 insertions(+), 1 deletion(-) create mode 100644 none/tests/x86/gnu_binutils_nop.c create mode 100644 none/tests/x86/gnu_binutils_nop.stderr.exp create mode 100644 none/tests/x86/gnu_binutils_nop.vgtest --- a/NEWS +++ b/NEWS @@ -9,6 +9,8 @@ The following bugs have been fixed or re file produced by mold 476708 valgrind-monitor.py regular expressions should use raw strings 477198 Add fchmodat2 syscall on linux +478624 Valgrind incompatibility with binutils-2.42 on x86 with new nop patterns + (unhandled instruction bytes: 0x2E 0x8D 0xB4 0x26) To see details of a given bug, visit https://bugs.kde.org/show_bug.cgi?id=XXXXXX --- a/VEX/priv/guest_x86_toIR.c +++ b/VEX/priv/guest_x86_toIR.c @@ -8198,7 +8198,7 @@ DisResult disInstr_X86_WRK ( delta += 5; goto decode_success; } - /* Don't barf on recent binutils padding, + /* Don't barf on recent (2010) binutils padding, all variants of which are: nopw %cs:0x0(%eax,%eax,1) 66 2e 0f 1f 84 00 00 00 00 00 66 66 2e 0f 1f 84 00 00 00 00 00 @@ -8222,6 +8222,26 @@ DisResult disInstr_X86_WRK ( goto decode_success; } } + + /* bug478624 GNU binutils uses a leal of esi into itself with + a zero offset and CS prefix as an 8 byte no-op (Dec 2023). + Since the CS prefix is hardly ever used we don't do much + to decode it, just a few cases for conditional branches. + So add handling here with other pseudo-no-ops. + */ + if (code[0] == 0x2E && code[1] == 0x8D) { + if (code[2] == 0x74 && code[3] == 0x26 && code[4] == 0x00) { + DIP("leal %%cs:0(%%esi,%%eiz,1),%%esi\n"); + delta += 5; + goto decode_success; + } + if (code[2] == 0xB4 && code[3] == 0x26 && code[4] == 0x00 + && code[5] == 0x00 && code[6] == 0x00 && code[7] == 0x00) { + DIP("leal %%cs:0(%%esi,%%eiz,1),%%esi\n"); + delta += 8; + goto decode_success; + } + } // Intel CET requires the following opcodes to be treated as NOPs // with any prefix and ModRM, SIB and disp combination: --- a/none/tests/x86/Makefile.am +++ b/none/tests/x86/Makefile.am @@ -52,6 +52,7 @@ EXTRA_DIST = \ fxtract.stdout.exp fxtract.stderr.exp fxtract.vgtest \ fxtract.stdout.exp-older-glibc \ getseg.stdout.exp getseg.stderr.exp getseg.vgtest \ + gnu_binutils_nop.stderr.exp gnu_binutils_nop.vgtest \ incdec_alt.stdout.exp incdec_alt.stderr.exp incdec_alt.vgtest \ int.stderr.exp int.stdout.exp int.disabled \ $(addsuffix .stderr.exp,$(INSN_TESTS)) \ @@ -100,6 +101,7 @@ check_PROGRAMS = \ fpu_lazy_eflags \ fxtract \ getseg \ + gnu_binutils_nop \ incdec_alt \ $(INSN_TESTS) \ int \ --- /dev/null +++ b/none/tests/x86/gnu_binutils_nop.c @@ -0,0 +1,34 @@ +int main(void) +{ + // GNU binutils uses various opcodes as alternatives for nop + // the idea is that it is faster to execute one large opcode + // with no side-effects than multiple repetitions of the + // single byte 'nop'. This gives more choice when code + // needs to be padded. + + // the following is based on + // https://sourceware.org/cgit/binutils-gdb/tree/gas/config/tc-i386.c#n1256 + + // one byte + __asm__ __volatile__("nop"); + // two bytes + __asm__ __volatile__("xchg %ax,%ax"); + // three bytes + //__asm__ __volatile__("leal 0(%esi),%esi"); + __asm__ __volatile__(".byte 0x8d,0x76,0x00"); + // four bytes + //__asm__ __volatile__("leal 0(%esi,%eiz),%esi"); + __asm__ __volatile__(".byte 0x8d,0x74,0x26,0x00"); + // five bytes + //__asm__ __volatile__("leal %cs:0(%esi,%eiz),%esi"); + __asm__ __volatile__(".byte 0x2e,0x8d,0x74,0x26,0x00"); + // six bytes + //__asm__ __volatile__("leal 0L(%esi),%esi"); + __asm__ __volatile__(".byte 0x8d,0xb6,0x00,0x00,0x00,0x00"); + // seven bytes + //__asm__ __volatile__("leal 0L(%esi,%eiz),%esi"); + __asm__ __volatile__(".byte 0x8d,0xb4,0x26,0x00,0x00,0x00,0x00"); + // eight bytes + //__asm__ __volatile__("leal %cs:0L(%esi,%eiz),%esi"); + __asm__ __volatile__(".byte 0x2e,0x8d,0xb4,0x26,0x00,0x00,0x00,0x00"); +} --- /dev/null +++ b/none/tests/x86/gnu_binutils_nop.vgtest @@ -0,0 +1,2 @@ +prog: gnu_binutils_nop +vgopts: -q