• Dave Hansen's avatar
    x86/fpu: Fix double-increment in setup_xstate_features() · a8424003
    Dave Hansen authored
    I noticed that my MPX tracepoints were producing garbage for the
    lower and upper bounds:
    
    	mpx_bounds_register_exception: address referenced: 0x00007fffffffccb7 bounds: lower: 0x0 ~upper: 0xffffffffffffffff
    	mpx_bounds_register_exception: address referenced: 0x00007fffffffccbf bounds: lower: 0x0 ~upper: 0xffffffffffffffff
    
    This is, of course, bogus because 0x00007fffffffccbf is *within*
    the bounds.  I assumed that my instruction decoder was bad and
    went looking at it.  But I eventually realized that I was
    getting a '0' offset back from xstate_offsets[BNDREGS].
    
    It was being skipped in the initialization, which is obviously
    bogus, so remove the extra leaf++.
    
    This also goes an initializes xstate_offsets/sizes[] to -1 so
    so that bugs like this will oops instead of silently failing
    in interesting ways.
    
    This was introduced by:
    
    	39f1acd2 ("x86/fpu/xstate: Don't assume the first zero xfeatures zero bit means the end")
    Signed-off-by: default avatarDave Hansen <dave.hansen@linux.intel.com>
    Cc: Andrew Morton <akpm@linux-foundation.org>
    Cc: Andy Lutomirski <luto@amacapital.net>
    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: Linus Torvalds <torvalds@linux-foundation.org>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Cc: dave@sr71.net
    Link: http://lkml.kernel.org/r/20150611193400.2E0B00DB@viggo.jf.intel.comSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
    a8424003
xstate.c 11.8 KB