Commit-ID: a8424003679e90b9952e20adcd1ff1560d9dd3e9
Gitweb: http://git.kernel.org/tip/a8424003679e90b9952e20adcd1ff1560d9dd3e9
Author: Dave Hansen <dave.han...@linux.intel.com>
AuthorDate: Thu, 11 Jun 2015 12:34:00 -0700
Committer: Ingo Molnar <mi...@kernel.org>
CommitDate: Fri, 12 Jun 2015 10:48:12 +0200
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.han...@linux.intel.com>
Cc: Andrew Morton <a...@linux-foundation.org>
Cc: Andy Lutomirski <l...@amacapital.net>
Cc: Borislav Petkov <b...@alien8.de>
Cc: Brian Gerst <brge...@gmail.com>
Cc: Denys Vlasenko <dvlas...@redhat.com>
Cc: H. Peter Anvin <h...@zytor.com>
Cc: Linus Torvalds <torva...@linux-foundation.org>
Cc: Peter Zijlstra <pet...@infradead.org>
Cc: Thomas Gleixner <t...@linutronix.de>
Cc: d...@sr71.net
Link: http://lkml.kernel.org/r/20150611193400.2e0b0...@viggo.jf.intel.com
Signed-off-by: Ingo Molnar <mi...@kernel.org>
---
arch/x86/kernel/fpu/xstate.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c
index 49d0d9b..62fc001 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++;
}
}
--
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