diff options
| author | Peter Zijlstra <peterz@infradead.org> | 2020-06-12 16:05:26 +0200 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2020-06-18 17:36:33 +0200 |
| commit | 0f1441b44e823a74f3f3780902a113e07c73fbf6 (patch) | |
| tree | 5ef3755754810974096c758d5878dc31d23d7c20 /tools/objtool/arch | |
| parent | fdabdd0b05e0bdf232340d5da86563ed142a99a7 (diff) | |
objtool: Fix noinstr vs KCOV
Since many compilers cannot disable KCOV with a function attribute,
help it to NOP out any __sanitizer_cov_*() calls injected in noinstr
code.
This turns:
12: e8 00 00 00 00 callq 17 <lockdep_hardirqs_on+0x17>
13: R_X86_64_PLT32 __sanitizer_cov_trace_pc-0x4
into:
12: 0f 1f 44 00 00 nopl 0x0(%rax,%rax,1)
13: R_X86_64_NONE __sanitizer_cov_trace_pc-0x4
Just like recordmcount does.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Dmitry Vyukov <dvyukov@google.com>
Diffstat (limited to 'tools/objtool/arch')
| -rw-r--r-- | tools/objtool/arch/x86/decode.c | 18 | ||||
| -rw-r--r-- | tools/objtool/arch/x86/include/arch_elf.h | 6 |
2 files changed, 24 insertions, 0 deletions
diff --git a/tools/objtool/arch/x86/decode.c b/tools/objtool/arch/x86/decode.c index 4b504fc90bbb..9872195f998b 100644 --- a/tools/objtool/arch/x86/decode.c +++ b/tools/objtool/arch/x86/decode.c @@ -565,3 +565,21 @@ void arch_initial_func_cfi_state(struct cfi_init_state *state) state->regs[16].base = CFI_CFA; state->regs[16].offset = -8; } + +const char *arch_nop_insn(int len) +{ + static const char nops[5][5] = { + /* 1 */ { 0x90 }, + /* 2 */ { 0x66, 0x90 }, + /* 3 */ { 0x0f, 0x1f, 0x00 }, + /* 4 */ { 0x0f, 0x1f, 0x40, 0x00 }, + /* 5 */ { 0x0f, 0x1f, 0x44, 0x00, 0x00 }, + }; + + if (len < 1 || len > 5) { + WARN("invalid NOP size: %d\n", len); + return NULL; + } + + return nops[len-1]; +} diff --git a/tools/objtool/arch/x86/include/arch_elf.h b/tools/objtool/arch/x86/include/arch_elf.h new file mode 100644 index 000000000000..69cc4264b28a --- /dev/null +++ b/tools/objtool/arch/x86/include/arch_elf.h @@ -0,0 +1,6 @@ +#ifndef _OBJTOOL_ARCH_ELF +#define _OBJTOOL_ARCH_ELF + +#define R_NONE R_X86_64_NONE + +#endif /* _OBJTOOL_ARCH_ELF */ |