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valgrind
VEX-x86-nop-pattern.patch
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File VEX-x86-nop-pattern.patch of Package valgrind
From d35005cef8ad8207542738812705ceabf137d7e0 Mon Sep 17 00:00:00 2001 From: Paul Floyd <pjfloyd@wanadoo.fr> Date: Sun, 17 Dec 2023 14:18:51 +0100 Subject: [PATCH] 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. --- .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 diff --git a/VEX/priv/guest_x86_toIR.c b/VEX/priv/guest_x86_toIR.c index 5d6e6dc64..3b6efb387 100644 --- 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 @@ -8223,6 +8223,26 @@ DisResult disInstr_X86_WRK ( } } + /* 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: // "0F 19", "0F 1C", "0F 1D", "0F 1E", "0F 1F" diff --git a/none/tests/x86/Makefile.am b/none/tests/x86/Makefile.am index 3ecd1ad3c..dbae86571 100644 --- 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 \ diff --git a/none/tests/x86/gnu_binutils_nop.c b/none/tests/x86/gnu_binutils_nop.c new file mode 100644 index 000000000..412a4c2cb --- /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"); +} diff --git a/none/tests/x86/gnu_binutils_nop.stderr.exp b/none/tests/x86/gnu_binutils_nop.stderr.exp new file mode 100644 index 000000000..e69de29bb diff --git a/none/tests/x86/gnu_binutils_nop.vgtest b/none/tests/x86/gnu_binutils_nop.vgtest new file mode 100644 index 000000000..7f378dd53 --- /dev/null +++ b/none/tests/x86/gnu_binutils_nop.vgtest @@ -0,0 +1,2 @@ +prog: gnu_binutils_nop +vgopts: -q -- 2.43.0
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