Commit-ID: a8424003679e90b9952e20adcd1ff1560d9dd3e9
Gitweb: http://git.kernel.org/tip/a8424003679e90b9952e20adcd1ff1560d9dd3e9
Author: Dave Hansen <[email protected]>
AuthorDate: Thu, 11 Jun 2015 12:34:00 -0700
Committer: Ingo Molnar <[email protected]>
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 <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Brian Gerst <[email protected]>
Cc: Denys Vlasenko <[email protected]>
Cc: H. Peter Anvin <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: [email protected]
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>
---
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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