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x86/fpu: Factor out FPU hw activation/deactivation

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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>
This commit is contained in:
Ingo Molnar 2015-04-27 08:58:45 +02:00
parent 67ee658e6f
commit 32b49b3c83
2 changed files with 27 additions and 12 deletions
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32
arch/x86/include/asm/fpu/internal.h
View File

@ -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;

7
arch/x86/kernel/fpu/core.c
View File

@ -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();