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Subject[PATCH 1/5] x86/fpu/xstate: Align xstate components according to CPUID
Date
CPUID function 0x0d, sub function (i, i > 1) returns in ecx[1] the
alignment requirement of component i when the compacted format is used.

If ecx[1] is 0, component i is located immediately following the preceding
component. If ecx[1] is 1, component i is located on the next 64-byte
boundary following the preceding component.

Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com>
Reviewed-by: Dave Hansen <dave.hansen@intel.com>
---
arch/x86/kernel/fpu/xstate.c | 60 +++++++++++++++++++++++---------------------
1 file changed, 32 insertions(+), 28 deletions(-)

diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c
index 0b01f00..e6fcfcc6 100644
--- a/arch/x86/kernel/fpu/xstate.c
+++ b/arch/x86/kernel/fpu/xstate.c
@@ -270,6 +270,33 @@ static void __init print_xstate_features(void)
}

/*
+ * This check is important because it is easy to get XSTATE_*
+ * confused with XSTATE_BIT_*.
+ */
+#define CHECK_XFEATURE(nr) do { \
+ WARN_ON(nr < FIRST_EXTENDED_XFEATURE); \
+ WARN_ON(nr >= XFEATURE_MAX); \
+} while (0)
+
+/*
+ * We could cache this like xstate_size[], but we only use
+ * it here, so it would be a waste of space.
+ */
+static int xfeature_is_aligned(int xfeature_nr)
+{
+ u32 eax, ebx, ecx, edx;
+
+ CHECK_XFEATURE(xfeature_nr);
+ cpuid_count(XSTATE_CPUID, xfeature_nr, &eax, &ebx, &ecx, &edx);
+ /*
+ * The value returned by ECX[1] indicates the alignment
+ * of state component i when the compacted format
+ * of the extended region of an XSAVE area is used
+ */
+ return !!(ecx & 2);
+}
+
+/*
* This function sets up offsets and sizes of all extended states in
* xsave area. This supports both standard format and compacted format
* of the xsave aread.
@@ -306,10 +333,14 @@ static void __init setup_xstate_comp(void)
else
xstate_comp_sizes[i] = 0;

- if (i > FIRST_EXTENDED_XFEATURE)
+ if (i > FIRST_EXTENDED_XFEATURE) {
xstate_comp_offsets[i] = xstate_comp_offsets[i-1]
+ xstate_comp_sizes[i-1];

+ if (xfeature_is_aligned(i))
+ xstate_comp_offsets[i] =
+ ALIGN(xstate_comp_offsets[i], 64);
+ }
}
}

@@ -366,33 +397,6 @@ static int xfeature_is_user(int xfeature_nr)
}
*/

-/*
- * This check is important because it is easy to get XSTATE_*
- * confused with XSTATE_BIT_*.
- */
-#define CHECK_XFEATURE(nr) do { \
- WARN_ON(nr < FIRST_EXTENDED_XFEATURE); \
- WARN_ON(nr >= XFEATURE_MAX); \
-} while (0)
-
-/*
- * We could cache this like xstate_size[], but we only use
- * it here, so it would be a waste of space.
- */
-static int xfeature_is_aligned(int xfeature_nr)
-{
- u32 eax, ebx, ecx, edx;
-
- CHECK_XFEATURE(xfeature_nr);
- cpuid_count(XSTATE_CPUID, xfeature_nr, &eax, &ebx, &ecx, &edx);
- /*
- * The value returned by ECX[1] indicates the alignment
- * of state component i when the compacted format
- * of the extended region of an XSAVE area is used
- */
- return !!(ecx & 2);
-}
-
static int xfeature_uncompacted_offset(int xfeature_nr)
{
u32 eax, ebx, ecx, edx;
--
1.9.1
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