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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: 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 2015-04-24 14:19:26 +02:00
parent 73a3aeb3ac
commit d5cea9b0af
4 changed files with 13 additions and 13 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
arch/x86/include/asm/fpu/api.h
View File

@ -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);

12
arch/x86/include/asm/fpu/internal.h
View File

@ -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) {

2
arch/x86/include/asm/fpu/types.h
View File

@ -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

10
arch/x86/kernel/fpu/core.c
View File

@ -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;