x86, xsave: reorganization of signal save/restore fpstate code layout

move 64bit routines that saves/restores fpstate in/from user stack from
signal_64.c to xsave.c

restore_i387_xstate() now handles the condition when user passes
NULL fpstate.

Other misc changes for prepartion of xsave/xrstor sigcontext support.

Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/include/asm-x86/i387.h b/include/asm-x86/i387.h
index 36dca8d..dc3745e 100644
--- a/include/asm-x86/i387.h
+++ b/include/asm-x86/i387.h
@@ -34,8 +34,9 @@
 #ifdef CONFIG_IA32_EMULATION
 extern unsigned int sig_xstate_ia32_size;
 struct _fpstate_ia32;
-extern int save_i387_ia32(struct _fpstate_ia32 __user *buf);
-extern int restore_i387_ia32(struct _fpstate_ia32 __user *buf);
+struct _xstate_ia32;
+extern int save_i387_xstate_ia32(void __user *buf);
+extern int restore_i387_xstate_ia32(void __user *buf);
 #endif
 
 #define X87_FSW_ES (1 << 7)	/* Exception Summary */
@@ -249,13 +250,13 @@
 	task_thread_info(tsk)->status &= ~TS_USEDFPU;
 }
 
+#endif	/* CONFIG_X86_64 */
+
 /*
  * Signal frame handlers...
  */
-extern int save_i387(struct _fpstate __user *buf);
-extern int restore_i387(struct _fpstate __user *buf);
-
-#endif	/* CONFIG_X86_64 */
+extern int save_i387_xstate(void __user *buf);
+extern int restore_i387_xstate(void __user *buf);
 
 static inline void __unlazy_fpu(struct task_struct *tsk)
 {