From: Peter Zijlstra peterz@infradead.org
[ Upstream commit 7a7621dfa417aa3715d2a3bd1bdd6cf5018274d0 ]
When 'discussing' control flow Masami mentioned the LOOP* instructions and I realized objtool doesn't decode them properly.
As it turns out, these instructions are somewhat inefficient and as such unlikely to be emitted by the compiler (a few vmlinux.o checks can't find a single one) so this isn't critical, but still, best to decode them properly.
Reported-by: Masami Hiramatsu (Google) mhiramat@kernel.org Signed-off-by: Peter Zijlstra (Intel) peterz@infradead.org Link: https://lkml.kernel.org/r/Yxhd4EMKyoFoH9y4@hirez.programming.kicks-ass.net Signed-off-by: Sasha Levin sashal@kernel.org --- tools/objtool/arch/x86/decode.c | 6 ++++++ 1 file changed, 6 insertions(+)
diff --git a/tools/objtool/arch/x86/decode.c b/tools/objtool/arch/x86/decode.c index a62e032863a8..4a7652719130 100644 --- a/tools/objtool/arch/x86/decode.c +++ b/tools/objtool/arch/x86/decode.c @@ -435,6 +435,12 @@ int arch_decode_instruction(struct elf *elf, struct section *sec, *type = INSN_CONTEXT_SWITCH; break;
+ case 0xe0: /* loopne */ + case 0xe1: /* loope */ + case 0xe2: /* loop */ + *type = INSN_JUMP_CONDITIONAL; + break; + case 0xe8: *type = INSN_CALL; break;