tree dbeb97d79e64df1492aae5b792c2b27139f696db
parent 4422d80ed7d4bdb2d6e9fb890c66c3d9250ba694
author Josh Poimboeuf <jpoimboe@redhat.com> 1499437182 -0500
committer Ingo Molnar <mingo@kernel.org> 1499502588 +0200

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>