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powerpc: Add the ability to save VSX without giving it up

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This patch adds the ability to be able to save the VSX registers to the
thread struct without giving up (disabling the facility) next time the
process returns to userspace.

This patch builds on a previous optimisation for the FPU and VEC registers
in the thread copy path to avoid a possibly pointless reload of VSX state.

Signed-off-by: Cyril Bur <cyrilbur@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This commit is contained in:
Cyril Bur 2016-02-29 17:53:51 +11:00 committed by Michael Ellerman
parent 6f515d842e
commit bf6a4d5b75
4 changed files with 30 additions and 37 deletions
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4
arch/powerpc/include/asm/switch_to.h
View File

@ -56,14 +56,10 @@ static inline void __giveup_altivec(struct task_struct *t) { }
#ifdef CONFIG_VSX
extern void enable_kernel_vsx(void);
extern void flush_vsx_to_thread(struct task_struct *);
extern void giveup_vsx(struct task_struct *);
extern void __giveup_vsx(struct task_struct *);
static inline void disable_kernel_vsx(void)
{
msr_check_and_clear(MSR_FP|MSR_VEC|MSR_VSX);
}
#else
static inline void __giveup_vsx(struct task_struct *t) { }
#endif
#ifdef CONFIG_SPE

4
arch/powerpc/kernel/ppc_ksyms.c
View File

@ -28,10 +28,6 @@ EXPORT_SYMBOL(load_vr_state);
EXPORT_SYMBOL(store_vr_state);
#endif
#ifdef CONFIG_VSX
EXPORT_SYMBOL_GPL(__giveup_vsx);
#endif
#ifdef CONFIG_EPAPR_PARAVIRT
EXPORT_SYMBOL(epapr_hypercall_start);
#endif

42
arch/powerpc/kernel/process.c
View File

@ -280,19 +280,31 @@ static inline int restore_altivec(struct task_struct *tsk) { return 0; }
#endif /* CONFIG_ALTIVEC */
#ifdef CONFIG_VSX
void giveup_vsx(struct task_struct *tsk)
static void __giveup_vsx(struct task_struct *tsk)
{
check_if_tm_restore_required(tsk);
msr_check_and_set(MSR_FP|MSR_VEC|MSR_VSX);
if (tsk->thread.regs->msr & MSR_FP)
__giveup_fpu(tsk);
if (tsk->thread.regs->msr & MSR_VEC)
__giveup_altivec(tsk);
tsk->thread.regs->msr &= ~MSR_VSX;
}
static void giveup_vsx(struct task_struct *tsk)
{
check_if_tm_restore_required(tsk);
msr_check_and_set(MSR_FP|MSR_VEC|MSR_VSX);
__giveup_vsx(tsk);
msr_check_and_clear(MSR_FP|MSR_VEC|MSR_VSX);
}
EXPORT_SYMBOL(giveup_vsx);
static void save_vsx(struct task_struct *tsk)
{
if (tsk->thread.regs->msr & MSR_FP)
save_fpu(tsk);
if (tsk->thread.regs->msr & MSR_VEC)
save_altivec(tsk);
}
void enable_kernel_vsx(void)
{
@ -335,6 +347,7 @@ static int restore_vsx(struct task_struct *tsk)
}
#else
static inline int restore_vsx(struct task_struct *tsk) { return 0; }
static inline void save_vsx(struct task_struct *tsk) { }
#endif /* CONFIG_VSX */
#ifdef CONFIG_SPE
@ -478,14 +491,19 @@ void save_all(struct task_struct *tsk)
msr_check_and_set(msr_all_available);
if (usermsr & MSR_FP)
save_fpu(tsk);
/*
* Saving the way the register space is in hardware, save_vsx boils
* down to a save_fpu() and save_altivec()
*/
if (usermsr & MSR_VSX) {
save_vsx(tsk);
} else {
if (usermsr & MSR_FP)
save_fpu(tsk);
if (usermsr & MSR_VEC)
save_altivec(tsk);
if (usermsr & MSR_VSX)
__giveup_vsx(tsk);
if (usermsr & MSR_VEC)
save_altivec(tsk);
}
if (usermsr & MSR_SPE)
__giveup_spe(tsk);

17
arch/powerpc/kernel/vector.S
View File

@ -151,23 +151,6 @@ _GLOBAL(load_up_vsx)
std r12,_MSR(r1)
b fast_exception_return
/*
* __giveup_vsx(tsk)
* Disable VSX for the task given as the argument.
* Does NOT save vsx registers.
*/
_GLOBAL(__giveup_vsx)
addi r3,r3,THREAD /* want THREAD of task */
ld r5,PT_REGS(r3)
cmpdi 0,r5,0
beq 1f
ld r4,_MSR-STACK_FRAME_OVERHEAD(r5)
lis r3,MSR_VSX@h
andc r4,r4,r3 /* disable VSX for previous task */
std r4,_MSR-STACK_FRAME_OVERHEAD(r5)
1:
blr
#endif /* CONFIG_VSX */