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| 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/check.c | |
| parent | fdabdd0b05e0bdf232340d5da86563ed142a99a7 (diff) | |
| download | linux-0f1441b44e823a74f3f3780902a113e07c73fbf6.tar.gz linux-0f1441b44e823a74f3f3780902a113e07c73fbf6.tar.bz2 linux-0f1441b44e823a74f3f3780902a113e07c73fbf6.zip | |
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/check.c')
| -rw-r--r-- | tools/objtool/check.c | 19 |
1 files changed, 19 insertions, 0 deletions
diff --git a/tools/objtool/check.c b/tools/objtool/check.c index 91a67db26165..478267a072d0 100644 --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -12,6 +12,7 @@ #include "check.h" #include "special.h" #include "warn.h" +#include "arch_elf.h" #include <linux/hashtable.h> #include <linux/kernel.h> @@ -766,6 +767,24 @@ static int add_call_destinations(struct objtool_file *file) insn->call_dest = rela->sym; /* + * Many compilers cannot disable KCOV with a function attribute + * so they need a little help, NOP out any KCOV calls from noinstr + * text. + */ + if (insn->sec->noinstr && + !strncmp(insn->call_dest->name, "__sanitizer_cov_", 16)) { + if (rela) { + rela->type = R_NONE; + elf_write_rela(file->elf, rela); + } + + elf_write_insn(file->elf, insn->sec, + insn->offset, insn->len, + arch_nop_insn(insn->len)); + insn->type = INSN_NOP; + } + + /* * Whatever stack impact regular CALLs have, should be undone * by the RETURN of the called function. * |