x86, fpu: remove unnecessary user_fpu_end() in save_xstate_sig()

Suresh Siddha · H. Peter Anvin · commit 377ffbcc536a · 2012-09-18T15:52:06.000-07:00
Few lines below we do drop_fpu() which is more safer. Remove the unnecessary user_fpu_end() in save_xstate_sig(), which allows the drop_fpu() to ignore any pending exceptions from the user-space and drop the current fpu. Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com> Link: http://lkml.kernel.org/r/1345842782-24175-3-git-send-email-suresh.b.siddha@intel.com Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
diff --git a/arch/x86/include/asm/fpu-internal.h b/arch/x86/include/asm/fpu-internal.h
@@ -412,22 +412,11 @@ static inline void __drop_fpu(struct task_struct *tsk)
 }
 
 /*
- * The actual user_fpu_begin/end() functions
- * need to be preemption-safe.
+ * Need to be preemption-safe.
  *
- * NOTE! user_fpu_end() must be used only after you
- * have saved the FP state, and user_fpu_begin() must
- * be used only immediately before restoring it.
- * These functions do not do any save/restore on
- * their own.
+ * NOTE! user_fpu_begin() must be used only immediately before restoring
+ * it. This function does not do any save/restore on their own.
  */
-static inline void user_fpu_end(void)
-{
-	preempt_disable();
-	__thread_fpu_end(current);
-	preempt_enable();
-}
-
 static inline void user_fpu_begin(void)
 {
 	preempt_disable();
diff --git a/arch/x86/kernel/xsave.c b/arch/x86/kernel/xsave.c
@@ -255,7 +255,6 @@ int save_xstate_sig(void __user *buf, void __user *buf_fx, int size)
 		/* Update the thread's fxstate to save the fsave header. */
 		if (ia32_fxstate)
 			fpu_fxsave(&tsk->thread.fpu);
-		user_fpu_end();
 	} else {
 		sanitize_i387_state(tsk);
 		if (__copy_to_user(buf_fx, xsave, xstate_size))
