From: Julien Thierry <jthierry@redhat.com>
Date: Tue, 15 Sep 2020 07:53:17 +0000 (+0100)
Subject: objtool: Ignore unreachable fake jumps
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=fb136219f0e2b417d84e67b2a3adc1f933997d04;p=linux.git

objtool: Ignore unreachable fake jumps

It is possible for alternative code to unconditionally jump out of the
alternative region. In such a case, if a fake jump is added at the end
of the alternative instructions, the fake jump will never be reached.
Since the fake jump is just a mean to make sure code validation does not
go beyond the set of alternatives, reaching it is not a requirement.

Signed-off-by: Julien Thierry <jthierry@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
---

diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index fd2edab8e6728..cd7c6698d3169 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -2648,6 +2648,9 @@ static bool ignore_unreachable_insn(struct instruction *insn)
 	    !strcmp(insn->sec->name, ".altinstr_aux"))
 		return true;
 
+	if (insn->type == INSN_JUMP_UNCONDITIONAL && insn->offset == FAKE_JUMP_OFFSET)
+		return true;
+
 	if (!insn->func)
 		return false;