Commit 9e98d62a authored Mar 27, 2020 by Julien Thierry Committed by Peter Zijlstra Apr 30, 2020

objtool: Remove check preventing branches within alternative



While jumping from outside an alternative region to the middle of an
alternative region is very likely wrong, jumping from an alternative
region into the same region is valid. It is a common pattern on arm64.

The first pattern is unlikely to happen in practice and checking only
for this adds a lot of complexity.

Just remove the current check.

Suggested-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Julien Thierry <jthierry@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Link: https://lkml.kernel.org/r/20200327152847.15294-6-jthierry@redhat.com

parent 0c98be81

tools/objtool/check.c

+0 −6

Original line number	Diff line number	Diff line
		@@ -2162,12 +2162,6 @@ static int validate_branch(struct objtool_file file, struct symbol func,

		sec = insn->sec;

		if (insn->alt_group && list_empty(&insn->alts)) {
		WARN_FUNC("don't know how to handle branch to middle of alternative instruction group",
		sec, insn->offset);
		return 1;
		}

		while (1) {
		next_insn = next_insn_same_sec(file, insn);

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