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powerpc: Remove UP only lazy floating point and vector optimisations

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The UP only lazy floating point and vector optimisations were written
back when SMP was not common, and neither glibc nor gcc used vector
instructions. Now SMP is very common, glibc aggressively uses vector
instructions and gcc autovectorises.

We want to add new optimisations that apply to both UP and SMP, but
in preparation for that remove these UP only optimisations.

Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This commit is contained in:
Anton Blanchard 2015-10-29 11:43:57 +11:00 committed by Michael Ellerman
parent 68bfa962bf
commit af1bbc3dd3
9 changed files with 1 additions and 304 deletions
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6
arch/powerpc/include/asm/processor.h
View File

@ -88,12 +88,6 @@ struct task_struct;
void start_thread(struct pt_regs *regs, unsigned long fdptr, unsigned long sp);
void release_thread(struct task_struct *);
/* Lazy FPU handling on uni-processor */
extern struct task_struct *last_task_used_math;
extern struct task_struct *last_task_used_altivec;
extern struct task_struct *last_task_used_vsx;
extern struct task_struct *last_task_used_spe;
#ifdef CONFIG_PPC32
#if CONFIG_TASK_SIZE > CONFIG_KERNEL_START

8
arch/powerpc/include/asm/switch_to.h
View File

@ -27,14 +27,6 @@ extern void giveup_spe(struct task_struct *);
extern void load_up_spe(struct task_struct *);
extern void switch_booke_debug_regs(struct debug_reg *new_debug);
#ifndef CONFIG_SMP
extern void discard_lazy_cpu_state(void);
#else
static inline void discard_lazy_cpu_state(void)
{
}
#endif
#ifdef CONFIG_PPC_FPU
extern void flush_fp_to_thread(struct task_struct *);
extern void giveup_fpu(struct task_struct *);

35
arch/powerpc/kernel/fpu.S
View File

@ -132,31 +132,6 @@ END_FTR_SECTION_IFSET(CPU_FTR_VSX)
SYNC
MTMSRD(r5) /* enable use of fpu now */
isync
/*
* For SMP, we don't do lazy FPU switching because it just gets too
* horrendously complex, especially when a task switches from one CPU
* to another. Instead we call giveup_fpu in switch_to.
*/
#ifndef CONFIG_SMP
LOAD_REG_ADDRBASE(r3, last_task_used_math)
toreal(r3)
PPC_LL r4,ADDROFF(last_task_used_math)(r3)
PPC_LCMPI 0,r4,0
beq 1f
toreal(r4)
addi r4,r4,THREAD /* want last_task_used_math->thread */
addi r10,r4,THREAD_FPSTATE
SAVE_32FPVSRS(0, R5, R10)
mffs fr0
stfd fr0,FPSTATE_FPSCR(r10)
PPC_LL r5,PT_REGS(r4)
toreal(r5)
PPC_LL r4,_MSR-STACK_FRAME_OVERHEAD(r5)
li r10,MSR_FP|MSR_FE0|MSR_FE1
andc r4,r4,r10 /* disable FP for previous task */
PPC_STL r4,_MSR-STACK_FRAME_OVERHEAD(r5)
1:
#endif /* CONFIG_SMP */
/* enable use of FP after return */
#ifdef CONFIG_PPC32
mfspr r5,SPRN_SPRG_THREAD /* current task's THREAD (phys) */
@ -175,11 +150,6 @@ END_FTR_SECTION_IFSET(CPU_FTR_VSX)
lfd fr0,FPSTATE_FPSCR(r10)
MTFSF_L(fr0)
REST_32FPVSRS(0, R4, R10)
#ifndef CONFIG_SMP
subi r4,r5,THREAD
fromreal(r4)
PPC_STL r4,ADDROFF(last_task_used_math)(r3)
#endif /* CONFIG_SMP */
/* restore registers and return */
/* we haven't used ctr or xer or lr */
blr
@ -226,11 +196,6 @@ END_FTR_SECTION_IFSET(CPU_FTR_VSX)
andc r4,r4,r3 /* disable FP for previous task */
PPC_STL r4,_MSR-STACK_FRAME_OVERHEAD(r5)
1:
#ifndef CONFIG_SMP
li r5,0
LOAD_REG_ADDRBASE(r4,last_task_used_math)
PPC_STL r5,ADDROFF(last_task_used_math)(r4)
#endif /* CONFIG_SMP */
blr
/*

32
arch/powerpc/kernel/head_fsl_booke.S
View File

@ -857,29 +857,6 @@ _GLOBAL(load_up_spe)
oris r5,r5,MSR_SPE@h
mtmsr r5 /* enable use of SPE now */
isync
/*
* For SMP, we don't do lazy SPE switching because it just gets too
* horrendously complex, especially when a task switches from one CPU
* to another. Instead we call giveup_spe in switch_to.
*/
#ifndef CONFIG_SMP
lis r3,last_task_used_spe@ha
lwz r4,last_task_used_spe@l(r3)
cmpi 0,r4,0
beq 1f
addi r4,r4,THREAD /* want THREAD of last_task_used_spe */
SAVE_32EVRS(0,r10,r4,THREAD_EVR0)
evxor evr10, evr10, evr10 /* clear out evr10 */
evmwumiaa evr10, evr10, evr10 /* evr10 <- ACC = 0 * 0 + ACC */
li r5,THREAD_ACC
evstddx evr10, r4, r5 /* save off accumulator */
lwz r5,PT_REGS(r4)
lwz r4,_MSR-STACK_FRAME_OVERHEAD(r5)
lis r10,MSR_SPE@h
andc r4,r4,r10 /* disable SPE for previous task */
stw r4,_MSR-STACK_FRAME_OVERHEAD(r5)
1:
#endif /* !CONFIG_SMP */
/* enable use of SPE after return */
oris r9,r9,MSR_SPE@h
mfspr r5,SPRN_SPRG_THREAD /* current task's THREAD (phys) */
@ -889,10 +866,6 @@ _GLOBAL(load_up_spe)
evlddx evr4,r10,r5
evmra evr4,evr4
REST_32EVRS(0,r10,r5,THREAD_EVR0)
#ifndef CONFIG_SMP
subi r4,r5,THREAD
stw r4,last_task_used_spe@l(r3)
#endif /* !CONFIG_SMP */
blr
/*
@ -1035,11 +1008,6 @@ _GLOBAL(giveup_spe)
andc r4,r4,r3 /* disable SPE for previous task */
stw r4,_MSR-STACK_FRAME_OVERHEAD(r5)
1:
#ifndef CONFIG_SMP
li r5,0
lis r4,last_task_used_spe@ha
stw r5,last_task_used_spe@l(r4)
#endif /* !CONFIG_SMP */
blr
#endif /* CONFIG_SPE */

7
arch/powerpc/kernel/idle_power7.S
View File

@ -89,13 +89,6 @@ _GLOBAL(power7_powersave_common)
std r0,_LINK(r1)
std r0,_NIP(r1)
#ifndef CONFIG_SMP
/* Make sure FPU, VSX etc... are flushed as we may lose
* state when going to nap mode
*/
bl discard_lazy_cpu_state
#endif /* CONFIG_SMP */
/* Hard disable interrupts */
mfmsr r9
rldicl r9,r9,48,1

113
arch/powerpc/kernel/process.c
View File

@ -67,13 +67,6 @@
extern unsigned long _get_SP(void);
#ifndef CONFIG_SMP
struct task_struct *last_task_used_math = NULL;
struct task_struct *last_task_used_altivec = NULL;
struct task_struct *last_task_used_vsx = NULL;
struct task_struct *last_task_used_spe = NULL;
#endif
#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
void giveup_fpu_maybe_transactional(struct task_struct *tsk)
{
@ -134,16 +127,14 @@ void flush_fp_to_thread(struct task_struct *tsk)
*/
preempt_disable();
if (tsk->thread.regs->msr & MSR_FP) {
#ifdef CONFIG_SMP
/*
* This should only ever be called for current or
* for a stopped child process. Since we save away
* the FP register state on context switch on SMP,
* the FP register state on context switch,
* there is something wrong if a stopped child appears
* to still have its FP state in the CPU registers.
*/
BUG_ON(tsk != current);
#endif
giveup_fpu_maybe_transactional(tsk);
}
preempt_enable();
@ -156,14 +147,10 @@ void enable_kernel_fp(void)
{
WARN_ON(preemptible());
#ifdef CONFIG_SMP
if (current->thread.regs && (current->thread.regs->msr & MSR_FP))
giveup_fpu_maybe_transactional(current);
else
giveup_fpu(NULL); /* just enables FP for kernel */
#else
giveup_fpu_maybe_transactional(last_task_used_math);
#endif /* CONFIG_SMP */
}
EXPORT_SYMBOL(enable_kernel_fp);
@ -172,14 +159,10 @@ void enable_kernel_altivec(void)
{
WARN_ON(preemptible());
#ifdef CONFIG_SMP
if (current->thread.regs && (current->thread.regs->msr & MSR_VEC))
giveup_altivec_maybe_transactional(current);
else
giveup_altivec_notask();
#else
giveup_altivec_maybe_transactional(last_task_used_altivec);
#endif /* CONFIG_SMP */
}
EXPORT_SYMBOL(enable_kernel_altivec);
@ -192,9 +175,7 @@ void flush_altivec_to_thread(struct task_struct *tsk)
if (tsk->thread.regs) {
preempt_disable();
if (tsk->thread.regs->msr & MSR_VEC) {
#ifdef CONFIG_SMP
BUG_ON(tsk != current);
#endif
giveup_altivec_maybe_transactional(tsk);
}
preempt_enable();
@ -208,14 +189,10 @@ void enable_kernel_vsx(void)
{
WARN_ON(preemptible());
#ifdef CONFIG_SMP
if (current->thread.regs && (current->thread.regs->msr & MSR_VSX))
giveup_vsx(current);
else
giveup_vsx(NULL); /* just enable vsx for kernel - force */
#else
giveup_vsx(last_task_used_vsx);
#endif /* CONFIG_SMP */
}
EXPORT_SYMBOL(enable_kernel_vsx);
@ -232,9 +209,7 @@ void flush_vsx_to_thread(struct task_struct *tsk)
if (tsk->thread.regs) {
preempt_disable();
if (tsk->thread.regs->msr & MSR_VSX) {
#ifdef CONFIG_SMP
BUG_ON(tsk != current);
#endif
giveup_vsx(tsk);
}
preempt_enable();
@ -249,14 +224,10 @@ void enable_kernel_spe(void)
{
WARN_ON(preemptible());
#ifdef CONFIG_SMP
if (current->thread.regs && (current->thread.regs->msr & MSR_SPE))
giveup_spe(current);
else
giveup_spe(NULL); /* just enable SPE for kernel - force */
#else
giveup_spe(last_task_used_spe);
#endif /* __SMP __ */
}
EXPORT_SYMBOL(enable_kernel_spe);
@ -265,9 +236,7 @@ void flush_spe_to_thread(struct task_struct *tsk)
if (tsk->thread.regs) {
preempt_disable();
if (tsk->thread.regs->msr & MSR_SPE) {
#ifdef CONFIG_SMP
BUG_ON(tsk != current);
#endif
tsk->thread.spefscr = mfspr(SPRN_SPEFSCR);
giveup_spe(tsk);
}
@ -276,32 +245,6 @@ void flush_spe_to_thread(struct task_struct *tsk)
}
#endif /* CONFIG_SPE */
#ifndef CONFIG_SMP
/*
* If we are doing lazy switching of CPU state (FP, altivec or SPE),
* and the current task has some state, discard it.
*/
void discard_lazy_cpu_state(void)
{
preempt_disable();
if (last_task_used_math == current)
last_task_used_math = NULL;
#ifdef CONFIG_ALTIVEC
if (last_task_used_altivec == current)
last_task_used_altivec = NULL;
#endif /* CONFIG_ALTIVEC */
#ifdef CONFIG_VSX
if (last_task_used_vsx == current)
last_task_used_vsx = NULL;
#endif /* CONFIG_VSX */
#ifdef CONFIG_SPE
if (last_task_used_spe == current)
last_task_used_spe = NULL;
#endif
preempt_enable();
}
#endif /* CONFIG_SMP */
#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)
@ -831,30 +774,9 @@ struct task_struct *__switch_to(struct task_struct *prev,
__switch_to_tm(prev);
#ifdef CONFIG_SMP
/* avoid complexity of lazy save/restore of fpu
* by just saving it every time we switch out if
* this task used the fpu during the last quantum.
*
* If it tries to use the fpu again, it'll trap and
* reload its fp regs. So we don't have to do a restore
* every switch, just a save.
* -- Cort
*/
if (prev->thread.regs && (prev->thread.regs->msr & MSR_FP))
giveup_fpu(prev);
#ifdef CONFIG_ALTIVEC
/*
* If the previous thread used altivec in the last quantum
* (thus changing altivec regs) then save them.
* We used to check the VRSAVE register but not all apps
* set it, so we don't rely on it now (and in fact we need
* to save & restore VSCR even if VRSAVE == 0). -- paulus
*
* On SMP we always save/restore altivec regs just to avoid the
* complexity of changing processors.
* -- Cort
*/
if (prev->thread.regs && (prev->thread.regs->msr & MSR_VEC))
giveup_altivec(prev);
#endif /* CONFIG_ALTIVEC */
@ -864,39 +786,10 @@ struct task_struct *__switch_to(struct task_struct *prev,
__giveup_vsx(prev);
#endif /* CONFIG_VSX */
#ifdef CONFIG_SPE
/*
* If the previous thread used spe in the last quantum
* (thus changing spe regs) then save them.
*
* On SMP we always save/restore spe regs just to avoid the
* complexity of changing processors.
*/
if ((prev->thread.regs && (prev->thread.regs->msr & MSR_SPE)))
giveup_spe(prev);
#endif /* CONFIG_SPE */
#else /* CONFIG_SMP */
#ifdef CONFIG_ALTIVEC
/* Avoid the trap. On smp this this never happens since
* we don't set last_task_used_altivec -- Cort
*/
if (new->thread.regs && last_task_used_altivec == new)
new->thread.regs->msr |= MSR_VEC;
#endif /* CONFIG_ALTIVEC */
#ifdef CONFIG_VSX
if (new->thread.regs && last_task_used_vsx == new)
new->thread.regs->msr |= MSR_VSX;
#endif /* CONFIG_VSX */
#ifdef CONFIG_SPE
/* Avoid the trap. On smp this this never happens since
* we don't set last_task_used_spe
*/
if (new->thread.regs && last_task_used_spe == new)
new->thread.regs->msr |= MSR_SPE;
#endif /* CONFIG_SPE */
#endif /* CONFIG_SMP */
#ifdef CONFIG_PPC_ADV_DEBUG_REGS
switch_booke_debug_regs(&new->thread.debug);
#else
@ -1111,13 +1004,10 @@ void show_regs(struct pt_regs * regs)
void exit_thread(void)
{
discard_lazy_cpu_state();
}
void flush_thread(void)
{
discard_lazy_cpu_state();
#ifdef CONFIG_HAVE_HW_BREAKPOINT
flush_ptrace_hw_breakpoint(current);
#else /* CONFIG_HAVE_HW_BREAKPOINT */
@ -1355,7 +1245,6 @@ void start_thread(struct pt_regs *regs, unsigned long start, unsigned long sp)
regs->msr = MSR_USER32;
}
#endif
discard_lazy_cpu_state();
#ifdef CONFIG_VSX
current->thread.used_vsr = 0;
#endif

18
arch/powerpc/kernel/signal_32.c
View File

@ -687,15 +687,6 @@ static long restore_user_regs(struct pt_regs *regs,
if (sig)
regs->msr = (regs->msr & ~MSR_LE) | (msr & MSR_LE);
/*
* Do this before updating the thread state in
* current->thread.fpr/vr/evr. That way, if we get preempted
* and another task grabs the FPU/Altivec/SPE, it won't be
* tempted to save the current CPU state into the thread_struct
* and corrupt what we are writing there.
*/
discard_lazy_cpu_state();
#ifdef CONFIG_ALTIVEC
/*
* Force the process to reload the altivec registers from
@ -798,15 +789,6 @@ static long restore_tm_user_regs(struct pt_regs *regs,
/* Restore the previous little-endian mode */
regs->msr = (regs->msr & ~MSR_LE) | (msr & MSR_LE);
/*
* Do this before updating the thread state in
* current->thread.fpr/vr/evr. That way, if we get preempted
* and another task grabs the FPU/Altivec/SPE, it won't be
* tempted to save the current CPU state into the thread_struct
* and corrupt what we are writing there.
*/
discard_lazy_cpu_state();
#ifdef CONFIG_ALTIVEC
regs->msr &= ~MSR_VEC;
if (msr & MSR_VEC) {

18
arch/powerpc/kernel/signal_64.c
View File

@ -349,15 +349,6 @@ static long restore_sigcontext(struct pt_regs *regs, sigset_t *set, int sig,
if (set != NULL)
err |= __get_user(set->sig[0], &sc->oldmask);
/*
* Do this before updating the thread state in
* current->thread.fpr/vr. That way, if we get preempted
* and another task grabs the FPU/Altivec, it won't be
* tempted to save the current CPU state into the thread_struct
* and corrupt what we are writing there.
*/
discard_lazy_cpu_state();
/*
* Force reload of FP/VEC.
* This has to be done before copying stuff into current->thread.fpr/vr
@ -464,15 +455,6 @@ static long restore_tm_sigcontexts(struct pt_regs *regs,
err |= __get_user(regs->dsisr, &sc->gp_regs[PT_DSISR]);
err |= __get_user(regs->result, &sc->gp_regs[PT_RESULT]);
/*
* Do this before updating the thread state in
* current->thread.fpr/vr. That way, if we get preempted
* and another task grabs the FPU/Altivec, it won't be
* tempted to save the current CPU state into the thread_struct
* and corrupt what we are writing there.
*/
discard_lazy_cpu_state();
/*
* Force reload of FP/VEC.
* This has to be done before copying stuff into current->thread.fpr/vr

68
arch/powerpc/kernel/vector.S
View File

@ -80,39 +80,6 @@ _GLOBAL(load_up_altivec)
MTMSRD(r5) /* enable use of AltiVec now */
isync
/*
* For SMP, we don't do lazy VMX switching because it just gets too
* horrendously complex, especially when a task switches from one CPU
* to another. Instead we call giveup_altvec in switch_to.
* VRSAVE isn't dealt with here, that is done in the normal context
* switch code. Note that we could rely on vrsave value to eventually
* avoid saving all of the VREGs here...
*/
#ifndef CONFIG_SMP
LOAD_REG_ADDRBASE(r3, last_task_used_altivec)
toreal(r3)
PPC_LL r4,ADDROFF(last_task_used_altivec)(r3)
PPC_LCMPI 0,r4,0
beq 1f
/* Save VMX state to last_task_used_altivec's THREAD struct */
toreal(r4)
addi r4,r4,THREAD
addi r6,r4,THREAD_VRSTATE
SAVE_32VRS(0,r5,r6)
mfvscr v0
li r10,VRSTATE_VSCR
stvx v0,r10,r6
/* Disable VMX for last_task_used_altivec */
PPC_LL r5,PT_REGS(r4)
toreal(r5)
PPC_LL r4,_MSR-STACK_FRAME_OVERHEAD(r5)
lis r10,MSR_VEC@h
andc r4,r4,r10
PPC_STL r4,_MSR-STACK_FRAME_OVERHEAD(r5)
1:
#endif /* CONFIG_SMP */
/* Hack: if we get an altivec unavailable trap with VRSAVE
* set to all zeros, we assume this is a broken application
* that fails to set it properly, and thus we switch it to
@ -141,12 +108,6 @@ _GLOBAL(load_up_altivec)
lvx v0,r10,r6
mtvscr v0
REST_32VRS(0,r4,r6)
#ifndef CONFIG_SMP
/* Update last_task_used_altivec to 'current' */
subi r4,r5,THREAD /* Back to 'current' */
fromreal(r4)
PPC_STL r4,ADDROFF(last_task_used_altivec)(r3)
#endif /* CONFIG_SMP */
/* restore registers and return */
blr
@ -199,11 +160,6 @@ ALT_FTR_SECTION_END_IFSET(CPU_FTR_VSX)
andc r4,r4,r3 /* disable FP for previous task */
PPC_STL r4,_MSR-STACK_FRAME_OVERHEAD(r5)
1:
#ifndef CONFIG_SMP
li r5,0
LOAD_REG_ADDRBASE(r4,last_task_used_altivec)
PPC_STL r5,ADDROFF(last_task_used_altivec)(r4)
#endif /* CONFIG_SMP */
blr
#ifdef CONFIG_VSX
@ -226,20 +182,6 @@ _GLOBAL(load_up_vsx)
andis. r5,r12,MSR_VEC@h
beql+ load_up_altivec /* skip if already loaded */
#ifndef CONFIG_SMP
ld r3,last_task_used_vsx@got(r2)
ld r4,0(r3)
cmpdi 0,r4,0
beq 1f
/* Disable VSX for last_task_used_vsx */
addi r4,r4,THREAD
ld r5,PT_REGS(r4)
ld r4,_MSR-STACK_FRAME_OVERHEAD(r5)
lis r6,MSR_VSX@h
andc r6,r4,r6
std r6,_MSR-STACK_FRAME_OVERHEAD(r5)
1:
#endif /* CONFIG_SMP */
ld r4,PACACURRENT(r13)
addi r4,r4,THREAD /* Get THREAD */
li r6,1
@ -247,11 +189,6 @@ _GLOBAL(load_up_vsx)
/* enable use of VSX after return */
oris r12,r12,MSR_VSX@h
std r12,_MSR(r1)
#ifndef CONFIG_SMP
/* Update last_task_used_vsx to 'current' */
ld r4,PACACURRENT(r13)
std r4,0(r3)
#endif /* CONFIG_SMP */
b fast_exception_return
/*
@ -277,11 +214,6 @@ _GLOBAL(__giveup_vsx)
andc r4,r4,r3 /* disable VSX for previous task */
std r4,_MSR-STACK_FRAME_OVERHEAD(r5)
1:
#ifndef CONFIG_SMP
li r5,0
ld r4,last_task_used_vsx@got(r2)
std r5,0(r4)
#endif /* CONFIG_SMP */
blr
#endif /* CONFIG_VSX */