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| author | Dave Hansen <dave.hansen@linux.intel.com> | 2015-06-11 12:34:00 -0700 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2015-06-12 10:48:12 +0200 |
| commit | a8424003679e90b9952e20adcd1ff1560d9dd3e9 (patch) | |
| tree | 23353c4cd86e4c77f6f3b1f01c5f410b63dc9917 /arch/x86/kernel/fpu/xstate.c | |
| parent | 97ac46a5087eaf87fd76ff7bb31ec9c896010442 (diff) | |
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>
Diffstat (limited to 'arch/x86/kernel/fpu/xstate.c')
| -rw-r--r-- | arch/x86/kernel/fpu/xstate.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c index 49d0d9b2a60a..62fc001c7846 100644 --- a/arch/x86/kernel/fpu/xstate.c +++ b/arch/x86/kernel/fpu/xstate.c @@ -31,7 +31,8 @@ static const char *xfeature_names[] = */ u64 xfeatures_mask __read_mostly; -static unsigned int xstate_offsets[XFEATURES_NR_MAX], xstate_sizes[XFEATURES_NR_MAX]; +static unsigned int xstate_offsets[XFEATURES_NR_MAX] = { [ 0 ... XFEATURES_NR_MAX - 1] = -1}; +static unsigned int xstate_sizes[XFEATURES_NR_MAX] = { [ 0 ... XFEATURES_NR_MAX - 1] = -1}; static unsigned int xstate_comp_offsets[sizeof(xfeatures_mask)*8]; /* The number of supported xfeatures in xfeatures_mask: */ @@ -187,7 +188,6 @@ static void __init setup_xstate_features(void) xstate_sizes[leaf] = eax; printk(KERN_INFO "x86/fpu: xstate_offset[%d]: %04x, xstate_sizes[%d]: %04x\n", leaf, ebx, leaf, eax); - leaf++; } } |