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objtool: Fix noinstr vs KCOV

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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>
This commit is contained in:
Peter Zijlstra
2020-06-12 16:05:26 +02:00
parent fdabdd0b05
commit 0f1441b44e
5 changed files with 46 additions and 1 deletions
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6
tools/objtool/arch/x86/include/arch_elf.h Normal file
View File

@@ -0,0 +1,6 @@
#ifndef _OBJTOOL_ARCH_ELF
#define _OBJTOOL_ARCH_ELF
#define R_NONE R_X86_64_NONE
#endif /* _OBJTOOL_ARCH_ELF */