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Commit d5cea9b0 authored by Ingo Molnar's avatar Ingo Molnar
Browse files

x86/fpu: Rename fpu->has_fpu to fpu->fpregs_active 



So the current code uses fpu->has_cpu to determine whether a given
user FPU context is actively loaded into the FPU's registers [*] and
that those registers represent the task's current FPU state.

But this term is not unambiguous: especially the distinction between
fpu->has_fpu, PF_USED_MATH and fpu_fpregs_owner_ctx is not clear.

Increase clarity by unambigously signalling that it's about
hardware registers being active right now, by renaming it to
fpu->fpregs_active.

( In later patches we'll use more of the 'fpregs' naming, which will
  make it easier to grep for as well. )

[*] There's the kernel_fpu_begin()/end() primitive that also
    activates FPU hw registers as well and uses them, without
    touching the fpu->fpregs_active flag.

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 73a3aeb3

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

+1 −1
Original line number Diff line number Diff line
@@ -96,7 +96,7 @@ static inline void irq_ts_restore(int TS_state) 
 */

static inline int user_has_fpu(void)

{

	return current->thread.fpu.has_fpu;

	return current->thread.fpu.fpregs_active;

}



extern void fpu__save(struct fpu *fpu);

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

+6 −6
Original line number Diff line number Diff line
@@ -308,7 +308,7 @@ static inline int restore_fpu_checking(struct fpu *fpu) 
			"fnclex\n\t"

			"emms\n\t"

			"fildl %P[addr]"	/* set F?P to defined value */

			: : [addr] "m" (fpu->has_fpu));

			: : [addr] "m" (fpu->fpregs_active));

	}



	return fpu_restore_checking(fpu);
@@ -317,14 +317,14 @@ static inline int restore_fpu_checking(struct fpu *fpu) 
/* Must be paired with an 'stts' after! */

static inline void __thread_clear_has_fpu(struct fpu *fpu)

{

	fpu->has_fpu = 0;

	fpu->fpregs_active = 0;

	this_cpu_write(fpu_fpregs_owner_ctx, NULL);

}



/* Must be paired with a 'clts' before! */

static inline void __thread_set_has_fpu(struct fpu *fpu)

{

	fpu->has_fpu = 1;

	fpu->fpregs_active = 1;

	this_cpu_write(fpu_fpregs_owner_ctx, fpu);

}
@@ -357,7 +357,7 @@ static inline void drop_fpu(struct fpu *fpu) 
	preempt_disable();

	fpu->counter = 0;



	if (fpu->has_fpu) {

	if (fpu->fpregs_active) {

		/* Ignore delayed exceptions from user space */

		asm volatile("1: fwait\n"

			     "2:\n"
@@ -416,14 +416,14 @@ switch_fpu_prepare(struct fpu *old_fpu, struct fpu *new_fpu, int cpu) 
	fpu.preload = new_fpu->fpstate_active &&

		      (use_eager_fpu() || new_fpu->counter > 5);



	if (old_fpu->has_fpu) {

	if (old_fpu->fpregs_active) {

		if (!fpu_save_init(old_fpu))

			old_fpu->last_cpu = -1;

		else

			old_fpu->last_cpu = cpu;



		/* But leave fpu_fpregs_owner_ctx! */

		old_fpu->has_fpu = 0;

		old_fpu->fpregs_active = 0;



		/* Don't change CR0.TS if we just switch! */

		if (fpu.preload) {

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

+1 −1
Original line number Diff line number Diff line
@@ -142,7 +142,7 @@ struct fpu { 
	 */

	unsigned int			last_cpu;



	unsigned int			has_fpu;

	unsigned int			fpregs_active;

	union thread_xstate		*state;

	/*

	 * This counter contains the number of consecutive context switches

arch/x86/kernel/fpu/core.c

+5 −5
Original line number Diff line number Diff line
@@ -62,7 +62,7 @@ static bool interrupted_kernel_fpu_idle(void) 
	if (use_eager_fpu())

		return true;



	return !current->thread.fpu.has_fpu && (read_cr0() & X86_CR0_TS);

	return !current->thread.fpu.fpregs_active && (read_cr0() & X86_CR0_TS);

}



/*
@@ -100,7 +100,7 @@ void __kernel_fpu_begin(void) 


	kernel_fpu_disable();



	if (fpu->has_fpu) {

	if (fpu->fpregs_active) {

		fpu_save_init(fpu);

	} else {

		this_cpu_write(fpu_fpregs_owner_ctx, NULL);
@@ -114,7 +114,7 @@ void __kernel_fpu_end(void) 
{

	struct fpu *fpu = &current->thread.fpu;



	if (fpu->has_fpu) {

	if (fpu->fpregs_active) {

		if (WARN_ON(restore_fpu_checking(fpu)))

			fpu_reset_state(fpu);

	} else if (!use_eager_fpu()) {
@@ -147,7 +147,7 @@ void fpu__save(struct fpu *fpu) 
	WARN_ON(fpu != &current->thread.fpu);



	preempt_disable();

	if (fpu->has_fpu) {

	if (fpu->fpregs_active) {

		if (use_eager_fpu()) {

			__save_fpu(fpu);

		} else {
@@ -243,7 +243,7 @@ static void fpu_copy(struct fpu *dst_fpu, struct fpu *src_fpu) 
int fpu__copy(struct fpu *dst_fpu, struct fpu *src_fpu)

{

	dst_fpu->counter = 0;

	dst_fpu->has_fpu = 0;

	dst_fpu->fpregs_active = 0;

	dst_fpu->state = NULL;

	dst_fpu->last_cpu = -1;