x86/fpu: Factor out FPU hw activation/deactivation

We have repeat patterns of:

	if (!use_eager_fpu())
		clts();

... to activate FPU registers, and:

	if (!use_eager_fpu())
		stts();

... to deactivate them.

Encapsulate these in:

	__fpregs_activate_hw();
	__fpregs_activate_hw();

and use them accordingly.

Doing this synchronizes the idiom with the fpu->fpregs_active
software-flag's handling functions, creating clear patterns of:

	__fpregs_activate_hw();
	__fpregs_activate(fpu);

etc., which improves readability.

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>

diff --git a/arch/x86/include/asm/fpu/internal.h b/arch/x86/include/asm/fpu/internal.h
index de19fc5..28556c6 100644 (file)
--- a/arch/x86/include/asm/fpu/internal.h
+++ b/arch/x86/include/asm/fpu/internal.h
@@ -324,14 +324,31 @@ static inline int restore_fpu_checking(struct fpu *fpu)
        return fpu_restore_checking(fpu);
 }
 
-/* Must be paired with an 'stts' after! */
+/*
+ * Wrap lazy FPU TS handling in a 'hw fpregs activation/deactivation'
+ * idiom, which is then paired with the sw-flag (fpregs_active) later on:
+ */
+
+static inline void __fpregs_activate_hw(void)
+{
+       if (!use_eager_fpu())
+               clts();
+}
+
+static inline void __fpregs_deactivate_hw(void)
+{
+       if (!use_eager_fpu())
+               stts();
+}
+
+/* Must be paired with an 'stts' (fpregs_deactivate_hw()) after! */
 static inline void __fpregs_deactivate(struct fpu *fpu)
 {
        fpu->fpregs_active = 0;
        this_cpu_write(fpu_fpregs_owner_ctx, NULL);
 }
 
-/* Must be paired with a 'clts' before! */
+/* Must be paired with a 'clts' (fpregs_activate_hw()) before! */
 static inline void __fpregs_activate(struct fpu *fpu)
 {
        fpu->fpregs_active = 1;
@@ -362,16 +379,14 @@ static inline int user_has_fpu(void)
  */
 static inline void fpregs_activate(struct fpu *fpu)
 {
-       if (!use_eager_fpu())
-               clts();
+       __fpregs_activate_hw();
        __fpregs_activate(fpu);
 }
 
 static inline void fpregs_deactivate(struct fpu *fpu)
 {
        __fpregs_deactivate(fpu);
-       if (!use_eager_fpu())
-               stts();
+       __fpregs_deactivate_hw();
 }
 
 static inline void drop_fpu(struct fpu *fpu)
@@ -455,8 +470,9 @@ switch_fpu_prepare(struct fpu *old_fpu, struct fpu *new_fpu, int cpu)
                        new_fpu->counter++;
                        __fpregs_activate(new_fpu);
                        prefetch(&new_fpu->state);
-               } else if (!use_eager_fpu())
-                       stts();
+               } else {
+                       __fpregs_deactivate_hw();
+               }
        } else {
                old_fpu->counter = 0;
                old_fpu->last_cpu = -1;

diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c
index a407bf5..a617aac 100644 (file)
--- a/arch/x86/kernel/fpu/core.c
+++ b/arch/x86/kernel/fpu/core.c
@@ -105,8 +105,7 @@ void __kernel_fpu_begin(void)
                copy_fpregs_to_fpstate(fpu);
        } else {
                this_cpu_write(fpu_fpregs_owner_ctx, NULL);
-               if (!use_eager_fpu())
-                       clts();
+               __fpregs_activate_hw();
        }
 }
 EXPORT_SYMBOL(__kernel_fpu_begin);
@@ -118,8 +117,8 @@ void __kernel_fpu_end(void)
        if (fpu->fpregs_active) {
                if (WARN_ON(restore_fpu_checking(fpu)))
                        fpu_reset_state(fpu);
-       } else if (!use_eager_fpu()) {
-               stts();
+       } else {
+               __fpregs_deactivate_hw();
        }
 
        kernel_fpu_enable();