Skip to content
  • Josh Poimboeuf's avatar
    x86/kconfig: Make it easier to switch to the new ORC unwinder · a34a766f
    Josh Poimboeuf authored
    
    
    A couple of Kconfig changes which make it much easier to switch to the
    new CONFIG_ORC_UNWINDER:
    
    1) Remove x86 dependencies on CONFIG_FRAME_POINTER for lockdep,
       latencytop, and fault injection.  x86 has a 'guess' unwinder which
       just scans the stack for kernel text addresses.  It's not 100%
       accurate but in many cases it's good enough.  This allows those users
       who don't want the text overhead of the frame pointer or ORC
       unwinders to still use these features.  More importantly, this also
       makes it much more straightforward to disable frame pointers.
    
    2) Make CONFIG_ORC_UNWINDER depend on !CONFIG_FRAME_POINTER.  While it
       would be possible to have both enabled, it doesn't really make sense
       to do so.  So enforce a sane configuration to prevent the user from
       making a dumb mistake.
    
    With these changes, when you disable CONFIG_FRAME_POINTER, "make
    oldconfig" will ask if you want to enable CONFIG_ORC_UNWINDER.
    
    Signed-off-by: default avatarJosh Poimboeuf <jpoimboe@redhat.com>
    Cc: Andy Lutomirski <luto@kernel.org>
    Cc: Borislav Petkov <bp@alien8.de>
    Cc: Brian Gerst <brgerst@gmail.com>
    Cc: Denys Vlasenko <dvlasenk@redhat.com>
    Cc: H. Peter Anvin <hpa@zytor.com>
    Cc: Jiri Slaby <jslaby@suse.cz>
    Cc: Linus Torvalds <torvalds@linux-foundation.org>
    Cc: Mike Galbraith <efault@gmx.de>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Cc: live-patching@vger.kernel.org
    Link: http://lkml.kernel.org/r/9985fb91ce5005fe33ea5cc2a20f14bd33c61d03.1500938583.git.jpoimboe@redhat.com
    
    
    Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
    a34a766f