x86/xsaves: Use xsaves/xrstors to save and restore xsave area

If xsaves is eanbled, use xsaves/xrstors instrucitons to save and restore
xstate. xsaves and xrstors support compacted format, init optimization,
modified optimization, and supervisor states.

Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Link: http://lkml.kernel.org/r/1401387164-43416-9-git-send-email-fenghua.yu@intel.com
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

diff --git a/arch/x86/include/asm/xsave.h b/arch/x86/include/asm/xsave.h
index 76c2459188c85880a75b918c1fe58ced235f7c6d..f9177a2a97e9b35a4464142dcbafab5acb18459e 100644 (file)
--- a/arch/x86/include/asm/xsave.h
+++ b/arch/x86/include/asm/xsave.h
@@ -65,6 +65,70 @@ extern int init_fpu(struct task_struct *child);
                        _ASM_EXTABLE(1b, 3b)            \
                        : [err] "=r" (err)
 
+/*
+ * Save processor xstate to xsave area.
+ */
+static inline int xsave_state(struct xsave_struct *fx, u64 mask)
+{
+       u32 lmask = mask;
+       u32 hmask = mask >> 32;
+       int err = 0;
+
+       /*
+        * If xsaves is enabled, xsaves replaces xsaveopt because
+        * it supports compact format and supervisor states in addition to
+        * modified optimization in xsaveopt.
+        *
+        * Otherwise, if xsaveopt is enabled, xsaveopt replaces xsave
+        * because xsaveopt supports modified optimization which is not
+        * supported by xsave.
+        *
+        * If none of xsaves and xsaveopt is enabled, use xsave.
+        */
+       alternative_input_2(
+               "1:"XSAVE,
+               "1:"XSAVEOPT,
+               X86_FEATURE_XSAVEOPT,
+               "1:"XSAVES,
+               X86_FEATURE_XSAVES,
+               [fx] "D" (fx), "a" (lmask), "d" (hmask) :
+               "memory");
+       asm volatile("2:\n\t"
+                    xstate_fault
+                    : "0" (0)
+                    : "memory");
+
+       return err;
+}
+
+/*
+ * Restore processor xstate from xsave area.
+ */
+static inline int xrstor_state(struct xsave_struct *fx, u64 mask)
+{
+       int err = 0;
+       u32 lmask = mask;
+       u32 hmask = mask >> 32;
+
+       /*
+        * Use xrstors to restore context if it is enabled. xrstors supports
+        * compacted format of xsave area which is not supported by xrstor.
+        */
+       alternative_input(
+               "1: " XRSTOR,
+               "1: " XRSTORS,
+               X86_FEATURE_XSAVES,
+               "D" (fx), "m" (*fx), "a" (lmask), "d" (hmask)
+               : "memory");
+
+       asm volatile("2:\n"
+                    xstate_fault
+                    : "0" (0)
+                    : "memory");
+
+       return err;
+}
+
 static inline int fpu_xrstor_checking(struct xsave_struct *fx)
 {
        int err;
@@ -130,26 +194,6 @@ static inline int xrestore_user(struct xsave_struct __user *buf, u64 mask)
        return err;
 }
 
-static inline void xrstor_state(struct xsave_struct *fx, u64 mask)
-{
-       u32 lmask = mask;
-       u32 hmask = mask >> 32;
-
-       asm volatile(".byte " REX_PREFIX "0x0f,0xae,0x2f\n\t"
-                    : : "D" (fx), "m" (*fx), "a" (lmask), "d" (hmask)
-                    :   "memory");
-}
-
-static inline void xsave_state(struct xsave_struct *fx, u64 mask)
-{
-       u32 lmask = mask;
-       u32 hmask = mask >> 32;
-
-       asm volatile(".byte " REX_PREFIX "0x0f,0xae,0x27\n\t"
-                    : : "D" (fx), "m" (*fx), "a" (lmask), "d" (hmask)
-                    :   "memory");
-}
-
 static inline void fpu_xsave(struct fpu *fpu)
 {
        /* This, however, we can work around by forcing the compiler to select