x86/xsaves: Define a macro for handling xsave/xrstor instruction fault

Define a macro to handle fault generated by xsave, xsaveopt, xsaves, xrstor,
and xrstors instructions. It is used in functions like xsave_state() etc.

Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Link: http://lkml.kernel.org/r/1401387164-43416-8-git-send-email-fenghua.yu@intel.com
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

arch/x86/include/asm/xsave.h

@@ -58,6 +58,13 @@ extern int init_fpu(struct task_struct *child);
 #define XRSTOR		".byte " REX_PREFIX "0x0f,0xae,0x2f"
 #define XRSTORS		".byte " REX_PREFIX "0x0f,0xc7,0x1f"
 
+#define xstate_fault	".section .fixup,\"ax\"\n"	\
+			"3:  movl $-1,%[err]\n"		\
+			"    jmp  2b\n"			\
+			".previous\n"			\
+			_ASM_EXTABLE(1b, 3b)		\
+			: [err] "=r" (err)
+
 static inline int fpu_xrstor_checking(struct xsave_struct *fx)
 {
 	int err;