x86/fpu: Use 'struct fpu' in restore_fpu_checking()

Migrate this function to pure 'struct fpu' usage.

Reviewed-by: Borislav Petkov <bp@alien8.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>

arch/x86/include/asm/fpu-internal.h

@@ -294,7 +294,7 @@ static inline int fpu_restore_checking(struct fpu *fpu)
 		return frstor_checking(&fpu->state->fsave);
 }
 
-static inline int restore_fpu_checking(struct task_struct *tsk)
+static inline int restore_fpu_checking(struct fpu *fpu)
 {
 	/*
 	 * AMD K7/K8 CPUs don't save/restore FDP/FIP/FOP unless an exception is
@@ -306,10 +306,10 @@ static inline int restore_fpu_checking(struct task_struct *tsk)
 			"fnclex\n\t"
 			"emms\n\t"
 			"fildl %P[addr]"	/* set F?P to defined value */
-			: : [addr] "m" (tsk->thread.fpu.has_fpu));
+			: : [addr] "m" (fpu->has_fpu));
 	}
 
-	return fpu_restore_checking(&tsk->thread.fpu);
+	return fpu_restore_checking(fpu);
 }
 
 /* Must be paired with an 'stts' after! */
@@ -456,8 +456,10 @@ static inline fpu_switch_t switch_fpu_prepare(struct task_struct *old, struct ta
  */
 static inline void switch_fpu_finish(struct task_struct *new, fpu_switch_t fpu)
 {
+	struct fpu *new_fpu = &new->thread.fpu;
+
 	if (fpu.preload) {
-		if (unlikely(restore_fpu_checking(new)))
+		if (unlikely(restore_fpu_checking(new_fpu)))
 			fpu_reset_state(new);
 	}
 }

arch/x86/kernel/fpu/core.c

@@ -116,7 +116,7 @@ void __kernel_fpu_end(void)
 	struct fpu *fpu = &me->thread.fpu;
 
 	if (fpu->has_fpu) {
-		if (WARN_ON(restore_fpu_checking(me)))
+		if (WARN_ON(restore_fpu_checking(fpu)))
 			fpu_reset_state(me);
 	} else if (!use_eager_fpu()) {
 		stts();
@@ -370,7 +370,7 @@ void fpu__restore(void)
 	/* Avoid __kernel_fpu_begin() right after __thread_fpu_begin() */
 	kernel_fpu_disable();
 	__thread_fpu_begin(fpu);
-	if (unlikely(restore_fpu_checking(tsk))) {
+	if (unlikely(restore_fpu_checking(fpu))) {
 		fpu_reset_state(tsk);
 		force_sig_info(SIGSEGV, SEND_SIG_PRIV, tsk);
 	} else {