objtool: Fix false positive warnings related to sibling calls

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>