x86/fpu: Fix double-increment in setup_xstate_features()
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:
39f1acd ("x86/fpu/xstate: Don't assume the first zero xfeatures zero bit means the end")
Signed-off-by: Dave 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.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
1 file changed