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authorIngo Molnar <mingo@elte.hu>2009-09-15 12:18:15 +0200
committerIngo Molnar <mingo@elte.hu>2009-09-15 12:18:15 +0200
commitdca2d6ac09d9ef59ff46820d4f0c94b08a671202 (patch)
treefdec753b842dad09e3a4151954fab3eb5c43500d /arch/x86/kernel/process_64.c
parentd6a65dffb30d8636b1e5d4c201564ef401a246cf (diff)
parent18240904960a39e582ced8ba8ececb10b8c22dd3 (diff)
Merge branch 'linus' into tracing/hw-breakpoints
Conflicts: arch/x86/kernel/process_64.c Semantic conflict fixed in: arch/x86/kvm/x86.c Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'arch/x86/kernel/process_64.c')
-rw-r--r--arch/x86/kernel/process_64.c36
1 files changed, 21 insertions, 15 deletions
diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index 89c46f1259d..72edac026a7 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -57,9 +57,6 @@
asmlinkage extern void ret_from_fork(void);
-DEFINE_PER_CPU(struct task_struct *, current_task) = &init_task;
-EXPORT_PER_CPU_SYMBOL(current_task);
-
DEFINE_PER_CPU(unsigned long, old_rsp);
static DEFINE_PER_CPU(unsigned char, is_idle);
@@ -399,9 +396,17 @@ __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);
/*
@@ -432,6 +437,13 @@ __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
@@ -472,9 +484,6 @@ __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.
*/
@@ -493,15 +502,12 @@ __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();
/*
* There's a problem with moving the arch_install_thread_hw_breakpoint()
* call before current is updated. Suppose a kernel breakpoint is