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Commit 32b49b3c authored by Ingo Molnar's avatar Ingo Molnar
Browse files

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: default avatarBorislav 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: default avatarIngo Molnar <mingo@kernel.org>
parent 67ee658e

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

+24 −8
Original line number Original line Diff line number Diff line
@@ -324,14 +324,31 @@ static inline int restore_fpu_checking(struct fpu *fpu) 
	return fpu_restore_checking(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)

static inline void __fpregs_deactivate(struct fpu *fpu)

{

{

	fpu->fpregs_active = 0;

	fpu->fpregs_active = 0;

	this_cpu_write(fpu_fpregs_owner_ctx, NULL);

	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)

static inline void __fpregs_activate(struct fpu *fpu)

{

{

	fpu->fpregs_active = 1;

	fpu->fpregs_active = 1;
@@ -362,16 +379,14 @@ static inline int user_has_fpu(void) 
 */

 */

static inline void fpregs_activate(struct fpu *fpu)

static inline void fpregs_activate(struct fpu *fpu)

{

{

	if (!use_eager_fpu())

	__fpregs_activate_hw();

		clts();

	__fpregs_activate(fpu);

	__fpregs_activate(fpu);

}

}





static inline void fpregs_deactivate(struct fpu *fpu)

static inline void fpregs_deactivate(struct fpu *fpu)

{

{

	__fpregs_deactivate(fpu);

	__fpregs_deactivate(fpu);

	if (!use_eager_fpu())

	__fpregs_deactivate_hw();

		stts();

}

}





static inline void drop_fpu(struct fpu *fpu)

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++;

			new_fpu->counter++;

			__fpregs_activate(new_fpu);

			__fpregs_activate(new_fpu);

			prefetch(&new_fpu->state);

			prefetch(&new_fpu->state);

		} else if (!use_eager_fpu())

		} else {

			stts();

			__fpregs_deactivate_hw();

		}

	} else {

	} else {

		old_fpu->counter = 0;

		old_fpu->counter = 0;

		old_fpu->last_cpu = -1;

		old_fpu->last_cpu = -1;

arch/x86/kernel/fpu/core.c

+3 −4
Original line number Original line Diff line number Diff line
@@ -105,8 +105,7 @@ void __kernel_fpu_begin(void) 
		copy_fpregs_to_fpstate(fpu);

		copy_fpregs_to_fpstate(fpu);

	} else {

	} else {

		this_cpu_write(fpu_fpregs_owner_ctx, NULL);

		this_cpu_write(fpu_fpregs_owner_ctx, NULL);

		if (!use_eager_fpu())

		__fpregs_activate_hw();

			clts();

	}

	}

}

}

EXPORT_SYMBOL(__kernel_fpu_begin);

EXPORT_SYMBOL(__kernel_fpu_begin);
@@ -118,8 +117,8 @@ void __kernel_fpu_end(void) 
	if (fpu->fpregs_active) {

	if (fpu->fpregs_active) {

		if (WARN_ON(restore_fpu_checking(fpu)))

		if (WARN_ON(restore_fpu_checking(fpu)))

			fpu_reset_state(fpu);

			fpu_reset_state(fpu);

	} else if (!use_eager_fpu()) {

	} else {

		stts();

		__fpregs_deactivate_hw();

	}

	}





	kernel_fpu_enable();

	kernel_fpu_enable();