powerpc: Remove UP only lazy floating point and vector optimisations
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>
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 3aabed4..e098f43 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -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 @@
*/
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 @@
{
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 @@
{
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 @@
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 @@
{
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 @@
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 @@
{
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 @@
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 @@
}
#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 @@
__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 @@
__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 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 @@
regs->msr = MSR_USER32;
}
#endif
- discard_lazy_cpu_state();
#ifdef CONFIG_VSX
current->thread.used_vsr = 0;
#endif