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author | Linus Torvalds <torvalds@linux-foundation.org> | 2009-09-14 14:58:08 (GMT) |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2009-09-14 14:58:08 (GMT) |
commit | 625037cc405eabbfd2a39e9297e583a94886225f (patch) | |
tree | c0a62f6cb2a565efb7cd494f558f0acbadcbabb0 /arch | |
parent | 8fafa0a789faaff4318cbfa9c2f827d2198505dc (diff) | |
parent | 17950c5b243f99cbabef173415ee988c52104d7e (diff) | |
download | linux-fsl-qoriq-625037cc405eabbfd2a39e9297e583a94886225f.tar.xz |
Merge branch 'x86-fpu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'x86-fpu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
x86-64: move clts into batch cpu state updates when preloading fpu
x86-64: move unlazy_fpu() into lazy cpu state part of context switch
x86-32: make sure clts is batched during context switch
x86: split out core __math_state_restore
Diffstat (limited to 'arch')
-rw-r--r-- | arch/x86/include/asm/i387.h | 1 | ||||
-rw-r--r-- | arch/x86/kernel/process_32.c | 27 | ||||
-rw-r--r-- | arch/x86/kernel/process_64.c | 33 | ||||
-rw-r--r-- | arch/x86/kernel/traps.c | 33 |
4 files changed, 61 insertions, 33 deletions
diff --git a/arch/x86/include/asm/i387.h b/arch/x86/include/asm/i387.h index fb7f0d6..0b20bbb 100644 --- a/arch/x86/include/asm/i387.h +++ b/arch/x86/include/asm/i387.h @@ -26,6 +26,7 @@ extern void fpu_init(void); extern void mxcsr_feature_mask_init(void); extern int init_fpu(struct task_struct *child); extern asmlinkage void math_state_restore(void); +extern void __math_state_restore(void); extern void init_thread_xstate(void); extern int dump_fpu(struct pt_regs *, struct user_i387_struct *); diff --git a/arch/x86/kernel/process_32.c b/arch/x86/kernel/process_32.c index 59f4524..a80eddd 100644 --- a/arch/x86/kernel/process_32.c +++ b/arch/x86/kernel/process_32.c @@ -350,14 +350,21 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p) *next = &next_p->thread; int cpu = smp_processor_id(); struct tss_struct *tss = &per_cpu(init_tss, cpu); + bool preload_fpu; /* never put a printk in __switch_to... printk() calls wake_up*() indirectly */ - __unlazy_fpu(prev_p); + /* + * If the task has used fpu the last 5 timeslices, just do a full + * restore of the math state immediately to avoid the trap; the + * chances of needing FPU soon are obviously high now + */ + preload_fpu = tsk_used_math(next_p) && next_p->fpu_counter > 5; + __unlazy_fpu(prev_p); /* we're going to use this soon, after a few expensive things */ - if (next_p->fpu_counter > 5) + if (preload_fpu) prefetch(next->xstate); /* @@ -398,6 +405,11 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p) task_thread_info(next_p)->flags & _TIF_WORK_CTXSW_NEXT)) __switch_to_xtra(prev_p, next_p, tss); + /* If we're going to preload the fpu context, make sure clts + is run while we're batching the cpu state updates. */ + if (preload_fpu) + clts(); + /* * Leave lazy mode, flushing any hypercalls made here. * This must be done before restoring TLS segments so @@ -407,15 +419,8 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p) */ arch_end_context_switch(next_p); - /* If the task has used fpu the last 5 timeslices, just do a full - * restore of the math state immediately to avoid the trap; the - * chances of needing FPU soon are obviously high now - * - * tsk_used_math() checks prevent calling math_state_restore(), - * which can sleep in the case of !tsk_used_math() - */ - if (tsk_used_math(next_p) && next_p->fpu_counter > 5) - math_state_restore(); + if (preload_fpu) + __math_state_restore(); /* * Restore %gs if needed (which is common) diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c index ebefb54..a28279d 100644 --- a/arch/x86/kernel/process_64.c +++ b/arch/x86/kernel/process_64.c @@ -386,9 +386,17 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p) int cpu = smp_processor_id(); struct tss_struct *tss = &per_cpu(init_tss, cpu); unsigned fsindex, gsindex; + bool preload_fpu; + + /* + * If the task has used fpu the last 5 timeslices, just do a full + * restore of the math state immediately to avoid the trap; the + * chances of needing FPU soon are obviously high now + */ + preload_fpu = tsk_used_math(next_p) && next_p->fpu_counter > 5; /* we're going to use this soon, after a few expensive things */ - if (next_p->fpu_counter > 5) + if (preload_fpu) prefetch(next->xstate); /* @@ -419,6 +427,13 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p) load_TLS(next, cpu); + /* Must be after DS reload */ + unlazy_fpu(prev_p); + + /* Make sure cpu is ready for new context */ + if (preload_fpu) + clts(); + /* * Leave lazy mode, flushing any hypercalls made here. * This must be done before restoring TLS segments so @@ -459,9 +474,6 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p) wrmsrl(MSR_KERNEL_GS_BASE, next->gs); prev->gsindex = gsindex; - /* Must be after DS reload */ - unlazy_fpu(prev_p); - /* * Switch the PDA and FPU contexts. */ @@ -480,15 +492,12 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p) task_thread_info(prev_p)->flags & _TIF_WORK_CTXSW_PREV)) __switch_to_xtra(prev_p, next_p, tss); - /* If the task has used fpu the last 5 timeslices, just do a full - * restore of the math state immediately to avoid the trap; the - * chances of needing FPU soon are obviously high now - * - * tsk_used_math() checks prevent calling math_state_restore(), - * which can sleep in the case of !tsk_used_math() + /* + * Preload the FPU context, now that we've determined that the + * task is likely to be using it. */ - if (tsk_used_math(next_p) && next_p->fpu_counter > 5) - math_state_restore(); + if (preload_fpu) + __math_state_restore(); return prev_p; } diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index 6fe85c2..8326492 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -795,6 +795,28 @@ asmlinkage void __attribute__((weak)) smp_threshold_interrupt(void) } /* + * __math_state_restore assumes that cr0.TS is already clear and the + * fpu state is all ready for use. Used during context switch. + */ +void __math_state_restore(void) +{ + struct thread_info *thread = current_thread_info(); + struct task_struct *tsk = thread->task; + + /* + * Paranoid restore. send a SIGSEGV if we fail to restore the state. + */ + if (unlikely(restore_fpu_checking(tsk))) { + stts(); + force_sig(SIGSEGV, tsk); + return; + } + + thread->status |= TS_USEDFPU; /* So we fnsave on switch_to() */ + tsk->fpu_counter++; +} + +/* * 'math_state_restore()' saves the current math information in the * old math state array, and gets the new ones from the current task * @@ -825,17 +847,8 @@ asmlinkage void math_state_restore(void) } clts(); /* Allow maths ops (or we recurse) */ - /* - * Paranoid restore. send a SIGSEGV if we fail to restore the state. - */ - if (unlikely(restore_fpu_checking(tsk))) { - stts(); - force_sig(SIGSEGV, tsk); - return; - } - thread->status |= TS_USEDFPU; /* So we fnsave on switch_to() */ - tsk->fpu_counter++; + __math_state_restore(); } EXPORT_SYMBOL_GPL(math_state_restore); |