linux-kernel - [PATCH] objtool: fix rare switch jump table pattern detection

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Date:   Wed, 26 Oct 2016 10:34:08 -0500
From:   Josh Poimboeuf <jpoimboe@...hat.com>
To:     Arnd Bergmann <arnd@...db.de>
Cc:     Ingo Molnar <mingo@...nel.org>, linux-kernel@...r.kernel.org
Subject: [PATCH] objtool: fix rare switch jump table pattern detection

The following commit:

  3732710ff6f2 ("objtool: Improve rare switch jump table pattern detection")

... improved objtool's ability to detect gcc switch statement jump
tables for gcc 6.  However the check to allow short jumps with the
scanned range of instructions wasn't quite right.  The pattern detection
should allow jumps to the indirect jump instruction itself.

This fixes the following warning:

  drivers/infiniband/sw/rxe/rxe_comp.o: warning: objtool: rxe_completer()+0x315: sibling call from callable instruction with changed frame pointer

Reported-by: Arnd Bergmann <arnd@...db.de>
Fixes: 3732710ff6f2 ("objtool: Improve rare switch jump table pattern detection")
Signed-off-by: Josh Poimboeuf <jpoimboe@...hat.com>
---
 tools/objtool/builtin-check.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/objtool/builtin-check.c b/tools/objtool/builtin-check.c
index 4490601..e8a1f69 100644
--- a/tools/objtool/builtin-check.c
+++ b/tools/objtool/builtin-check.c
@@ -754,7 +754,7 @@ static struct rela *find_switch_table(struct objtool_file *file,
 		if (insn->type == INSN_JUMP_UNCONDITIONAL &&
 		    insn->jump_dest &&
 		    (insn->jump_dest->offset <= insn->offset ||
-		     insn->jump_dest->offset >= orig_insn->offset))
+		     insn->jump_dest->offset > orig_insn->offset))
 		    break;
 
 		text_rela = find_rela_by_dest_range(insn->sec, insn->offset,
-- 
2.7.4