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powerpc: create giveup_all()

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Create a single function that gives everything up (FP, VMX, VSX, SPE).
Doing this all at once means we only do one MSR write.

A context switch microbenchmark using yield():

http://ozlabs.org/~anton/junkcode/context_switch2.c

./context_switch2 --test=yield --fp --altivec --vector 0 0

shows an improvement of 3% on POWER8.

Signed-off-by: Anton Blanchard <anton@samba.org>
[mpe: giveup_all() needs to be EXPORT_SYMBOL'ed]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This commit is contained in:
Anton Blanchard 2015-10-29 11:44:08 +11:00 committed by Michael Ellerman
parent 1f2e25b2d5
commit c208505900
3 changed files with 64 additions and 30 deletions
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1
arch/powerpc/include/asm/switch_to.h
View File

@ -26,6 +26,7 @@ extern void __giveup_vsx(struct task_struct *);
extern void giveup_vsx(struct task_struct *);
extern void enable_kernel_spe(void);
extern void load_up_spe(struct task_struct *);
extern void giveup_all(struct task_struct *);
extern void switch_booke_debug_regs(struct debug_reg *new_debug);
#ifdef CONFIG_PPC_FPU

76
arch/powerpc/kernel/process.c
View File

@ -308,6 +308,65 @@ void flush_spe_to_thread(struct task_struct *tsk)
}
#endif /* CONFIG_SPE */
static unsigned long msr_all_available;
static int __init init_msr_all_available(void)
{
#ifdef CONFIG_PPC_FPU
msr_all_available |= MSR_FP;
#endif
#ifdef CONFIG_ALTIVEC
if (cpu_has_feature(CPU_FTR_ALTIVEC))
msr_all_available |= MSR_VEC;
#endif
#ifdef CONFIG_VSX
if (cpu_has_feature(CPU_FTR_VSX))
msr_all_available |= MSR_VSX;
#endif
#ifdef CONFIG_SPE
if (cpu_has_feature(CPU_FTR_SPE))
msr_all_available |= MSR_SPE;
#endif
return 0;
}
early_initcall(init_msr_all_available);
void giveup_all(struct task_struct *tsk)
{
unsigned long usermsr;
if (!tsk->thread.regs)
return;
usermsr = tsk->thread.regs->msr;
if ((usermsr & msr_all_available) == 0)
return;
msr_check_and_set(msr_all_available);
#ifdef CONFIG_PPC_FPU
if (usermsr & MSR_FP)
__giveup_fpu(tsk);
#endif
#ifdef CONFIG_ALTIVEC
if (usermsr & MSR_VEC)
__giveup_altivec(tsk);
#endif
#ifdef CONFIG_VSX
if (usermsr & MSR_VSX)
__giveup_vsx(tsk);
#endif
#ifdef CONFIG_SPE
if (usermsr & MSR_SPE)
__giveup_spe(tsk);
#endif
msr_check_and_clear(msr_all_available);
}
EXPORT_SYMBOL(giveup_all);
#ifdef CONFIG_PPC_ADV_DEBUG_REGS
void do_send_trap(struct pt_regs *regs, unsigned long address,
unsigned long error_code, int signal_code, int breakpt)
@ -839,21 +898,8 @@ struct task_struct *__switch_to(struct task_struct *prev,
__switch_to_tm(prev);
if (prev->thread.regs && (prev->thread.regs->msr & MSR_FP))
giveup_fpu(prev);
#ifdef CONFIG_ALTIVEC
if (prev->thread.regs && (prev->thread.regs->msr & MSR_VEC))
giveup_altivec(prev);
#endif /* CONFIG_ALTIVEC */
#ifdef CONFIG_VSX
if (prev->thread.regs && (prev->thread.regs->msr & MSR_VSX))
/* VMX and FPU registers are already save here */
__giveup_vsx(prev);
#endif /* CONFIG_VSX */
#ifdef CONFIG_SPE
if ((prev->thread.regs && (prev->thread.regs->msr & MSR_SPE)))
giveup_spe(prev);
#endif /* CONFIG_SPE */
/* Save FPU, Altivec, VSX and SPE state */
giveup_all(prev);
#ifdef CONFIG_PPC_ADV_DEBUG_REGS
switch_booke_debug_regs(&new->thread.debug);

17
arch/powerpc/kvm/book3s_pr.c
View File

@ -1490,21 +1490,8 @@ static int kvmppc_vcpu_run_pr(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu)
goto out;
/* interrupts now hard-disabled */
/* Save FPU state in thread_struct */
if (current->thread.regs->msr & MSR_FP)
giveup_fpu(current);
#ifdef CONFIG_ALTIVEC
/* Save Altivec state in thread_struct */
if (current->thread.regs->msr & MSR_VEC)
giveup_altivec(current);
#endif
#ifdef CONFIG_VSX
/* Save VSX state in thread_struct */
if (current->thread.regs->msr & MSR_VSX)
__giveup_vsx(current);
#endif
/* Save FPU, Altivec and VSX state */
giveup_all(current);
/* Preload FPU if it's enabled */
if (kvmppc_get_msr(vcpu) & MSR_FP)