objtool: Fix false positive warnings related to sibling calls
With some configs [1], objtool prints a bunch of false positive warnings
like:
arch/x86/events/core.o: warning: objtool: x86_del_exclusive()+0x0: frame pointer state mismatch
For some reason this config has a bunch of sibling calls. When objtool
follows a sibling call jump, it attempts to compare the frame pointer
state. But it also accidentally compares the FENTRY state, resulting in
a false positive warning.
[1] https://lkml.kernel.org/r/20160308154909.GA20956@gmail.com
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Bernd Petrovitsch <bernd@petrovitsch.priv.at>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Chris J Arges <chris.j.arges@canonical.com>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Michal Marek <mmarek@suse.cz>
Cc: Namhyung Kim <namhyung@gmail.com>
Cc: Pedro Alves <palves@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: live-patching@vger.kernel.org
Link: http://lkml.kernel.org/r/382de77ccaaa8cd79b27a155c3d109ebd4ce0219.1457502970.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
diff --git a/tools/objtool/builtin-check.c b/tools/objtool/builtin-check.c
index 51da270..fe24804 100644
--- a/tools/objtool/builtin-check.c
+++ b/tools/objtool/builtin-check.c
@@ -729,6 +729,11 @@
(insn->state & STATE_FP_SETUP);
}
+static unsigned int frame_state(unsigned long state)
+{
+ return (state & (STATE_FP_SAVED | STATE_FP_SETUP));
+}
+
/*
* Follow the branch starting at the given instruction, and recursively follow
* any other branches (jumps). Meanwhile, track the frame pointer state at
@@ -756,7 +761,7 @@
while (1) {
if (insn->visited) {
- if (insn->state != state) {
+ if (frame_state(insn->state) != frame_state(state)) {
WARN_FUNC("frame pointer state mismatch",
sec, insn->offset);
warnings++;