• Josh Poimboeuf's avatar
    objtool: Fix sibling call detection logic · 4855022a
    Josh Poimboeuf authored
    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: default avatarMike Galbraith <efault@gmx.de>
    Signed-off-by: default avatarJosh 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.comSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
    4855022a
check.c 39.7 KB