diff options
authorJosh Poimboeuf <jpoimboe@redhat.com>2017-07-07 09:19:42 -0500
committerIngo Molnar <mingo@kernel.org>2017-07-08 10:29:48 +0200
commit4855022a52262411ce38c93dec4cb1470705c0a0 (patch)
parent4422d80ed7d4bdb2d6e9fb890c66c3d9250ba694 (diff)
objtool: Fix sibling call detection logic
With some configs, objtool reports the following warning: arch/x86/kernel/ftrace.o: warning: objtool: ftrace_modify_code_direct()+0x2d: sibling call from callable instruction with modified stack frame The instruction it's complaining about isn't actually a sibling call. It's just a normal jump to an address inside the function. Objtool thought it was a sibling call because the instruction's jump_dest wasn't initialized because the function was supposed to be ignored due to its use of sync_core(). Objtool ended up validating the function instead of ignoring it because it didn't properly recognize a sibling call to the function. So fix the sibling call logic. Also add a warning to catch ignored functions being validated so we'll get a more useful error message next time. Reported-by: Mike Galbraith <efault@gmx.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/96cc8ecbcdd8cb29ddd783817b4af918a6a171b0.1499437107.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
1 files changed, 11 insertions, 2 deletions
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index fea222192c57..2c6d74880403 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -1371,6 +1371,12 @@ static int validate_branch(struct objtool_file *file, struct instruction *first,
func = insn->func;
+ if (func && insn->ignore) {
+ WARN_FUNC("BUG: why am I validating an ignored function?",
+ sec, insn->offset);
+ return -1;
+ }
if (insn->visited) {
if (!!insn_state_match(insn, &state))
return 1;
@@ -1426,16 +1432,19 @@ static int validate_branch(struct objtool_file *file, struct instruction *first,
- if (insn->jump_dest) {
+ if (insn->jump_dest &&
+ (!func || !insn->jump_dest->func ||
+ func == insn->jump_dest->func)) {
ret = validate_branch(file, insn->jump_dest,
if (ret)
return 1;
} else if (func && has_modified_stack_frame(&state)) {
WARN_FUNC("sibling call from callable instruction with modified stack frame",
sec, insn->offset);
return 1;
- } /* else it's a sibling call */
+ }
if (insn->type == INSN_JUMP_UNCONDITIONAL)
return 0;