• Mathias Krause's avatar
    x86/extable: ensure entries are swapped completely when sorting · 50c73890
    Mathias Krause authored
    The x86 exception table sorting was changed in commit 29934b0f
    ("x86/extable: use generic search and sort routines") to use the arch
    independent code in lib/extable.c.  However, the patch was mangled
    somehow on its way into the kernel from the last version posted at [1].
    The committed version kind of attempted to incorporate the changes of
    commit 548acf19 ("x86/mm: Expand the exception table logic to allow
    new handling options") as in _completely_ _ignoring_ the x86 specific
    'handler' member of struct exception_table_entry.  This effectively
    broke the sorting as entries will only partly be swapped now.
    
    Fortunately, the x86 Kconfig selects BUILDTIME_EXTABLE_SORT, so the
    exception table doesn't need to be sorted at runtime. However, in case
    that ever changes, we better not break the exception table sorting just
    because of that.
    
    [ Ard Biesheuvel points out that BUILDTIME_EXTABLE_SORT applies to the
      core image only, but we still rely on the sorting routines for modules
      in that case - Linus ]
    
    Fix this by providing a swap_ex_entry_fixup() macro that takes care of
    the 'handler' member.
    
    [1] https://lkml.org/lkml/2016/1/27/232Signed-off-by: default avatarMathias Krause <minipli@googlemail.com>
    Fixes: 29934b0f ("x86/extable: use generic search and sort routines")
    Reviewed-by: default avatarArd Biesheuvel <ard.biesheuvel@linaro.org>
    Cc: Andrew Morton <akpm@linux-foundation.org>
    Cc: Andy Lutomirski <luto@kernel.org>
    Cc: Borislav Petkov <bp@suse.de>
    Cc: H. Peter Anvin <hpa@linux.intel.com>
    Cc: Ingo Molnar <mingo@kernel.org>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Cc: Tony Luck <tony.luck@intel.com>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    50c73890
uaccess.h 23.9 KB