Commit 0e2bb2bc authored Jul 27, 2017 by Josh Poimboeuf Committed by Ingo Molnar Jul 28, 2017

objtool: Skip unreachable warnings for 'alt' instructions



When a whitelisted function uses one of the ALTERNATIVE macros, it
produces false positive warnings like:

  arch/x86/kvm/vmx.o: warning: objtool: .altinstr_replacement+0x0: unreachable instruction
  arch/x86/kvm/svm.o: warning: objtool: .altinstr_replacement+0x6e: unreachable instruction

There's no easy way to whitelist alternative instructions, so instead
just skip any 'unreachable' warnings associated with them.

Reported-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/a5d0a8c60155f03b36a31fac871e12cf75f35fd0.1501188854.git.jpoimboe@redhat.com


Signed-off-by: Ingo Molnar <mingo@kernel.org>

parent 649ea4d5

tools/objtool/check.c

+6 −1

Original line number	Diff line number	Diff line
		@@ -1746,8 +1746,13 @@ static bool ignore_unreachable_insn(struct instruction *insn)
		/*
		* Ignore any unused exceptions. This can happen when a whitelisted
		* function has an exception table entry.
		*
		* Also ignore alternative replacement instructions. This can happen
		* when a whitelisted function uses one of the ALTERNATIVE macros.
		*/
		if (!strcmp(insn->sec->name, ".fixup"))
		if (!strcmp(insn->sec->name, ".fixup") \|\|
		!strcmp(insn->sec->name, ".altinstr_replacement") \|\|
		!strcmp(insn->sec->name, ".altinstr_aux"))
		return true;

		/*

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