Merge branch 'linus' into timers/nohz

1 files changed, 43 insertions, 51 deletions

diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index c0a5c2a687e6..9a10c1897921 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -56,15 +56,6 @@ asmlinkage extern void ret_from_fork(void);
 
 unsigned long kernel_thread_flags = CLONE_VM | CLONE_UNTRACED;
 
-unsigned long boot_option_idle_override = 0;
-EXPORT_SYMBOL(boot_option_idle_override);
-
-/*
- * Powermanagement idle function, if any..
- */
-void (*pm_idle)(void);
-EXPORT_SYMBOL(pm_idle);
-
 static ATOMIC_NOTIFIER_HEAD(idle_notifier);
 
 void idle_notifier_register(struct notifier_block *n)
@@ -94,25 +85,6 @@ void exit_idle(void)
         __exit_idle();
 }
 
-/*
- * We use this if we don't have any better
- * idle routine..
- */
-void default_idle(void)
-{
-        current_thread_info()->status &= ~TS_POLLING;
-        /*
-         * TS_POLLING-cleared state must be visible before we
-         * test NEED_RESCHED:
-         */
-        smp_mb();
-        if (!need_resched())
-                safe_halt();    /* enables interrupts racelessly */
-        else
-                local_irq_enable();
-        current_thread_info()->status |= TS_POLLING;
-}
-
 #ifdef CONFIG_HOTPLUG_CPU
 DECLARE_PER_CPU(int, cpu_state);
 
@@ -150,12 +122,9 @@ void cpu_idle(void)
         while (1) {
                 tick_nohz_stop_sched_tick(1);
                 while (!need_resched()) {
-                        void (*idle)(void);
 
                         rmb();
-                        idle = pm_idle;
-                        if (!idle)
-                                idle = default_idle;
+
                         if (cpu_is_offline(smp_processor_id()))
                                 play_dead();
                         /*
@@ -165,7 +134,10 @@ void cpu_idle(void)
                          */
                         local_irq_disable();
                         enter_idle();
-                        idle();
+                        /* Don't trace irqs off for idle */
+                        stop_critical_timings();
+                        pm_idle();
+                        start_critical_timings();
                         /* In many cases the interrupt that ended idle
                            has already called exit_idle. But some idle
                            loops can be woken up without interrupt. */
@@ -294,6 +266,7 @@ void flush_thread(void)
         /*
          * Forget coprocessor state..
          */
+        tsk->fpu_counter = 0;
         clear_fpu(tsk);
         clear_used_math();
 }
@@ -365,10 +338,10 @@ int copy_thread(int nr, unsigned long clone_flags, unsigned long sp,
         p->thread.fs = me->thread.fs;
         p->thread.gs = me->thread.gs;
 
-        asm("mov %%gs,%0" : "=m" (p->thread.gsindex));
-        asm("mov %%fs,%0" : "=m" (p->thread.fsindex));
-        asm("mov %%es,%0" : "=m" (p->thread.es));
-        asm("mov %%ds,%0" : "=m" (p->thread.ds));
+        savesegment(gs, p->thread.gsindex);
+        savesegment(fs, p->thread.fsindex);
+        savesegment(es, p->thread.es);
+        savesegment(ds, p->thread.ds);
 
         if (unlikely(test_tsk_thread_flag(me, TIF_IO_BITMAP))) {
                 p->thread.io_bitmap_ptr = kmalloc(IO_BITMAP_BYTES, GFP_KERNEL);
@@ -407,7 +380,9 @@ out:
 void
 start_thread(struct pt_regs *regs, unsigned long new_ip, unsigned long new_sp)
 {
-        asm volatile("movl %0, %%fs; movl %0, %%es; movl %0, %%ds" :: "r"(0));
+        loadsegment(fs, 0);
+        loadsegment(es, 0);
+        loadsegment(ds, 0);
         load_gs_index(0);
         regs->ip                = new_ip;
         regs->sp                = new_sp;
@@ -566,6 +541,7 @@ __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);
+        unsigned fsindex, gsindex;
 
         /* we're going to use this soon, after a few expensive things */
         if (next_p->fpu_counter>5)
@@ -580,22 +556,38 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
          * Switch DS and ES.
          * This won't pick up thread selector changes, but I guess that is ok.
          */
-        asm volatile("mov %%es,%0" : "=m" (prev->es));
+        savesegment(es, prev->es);
         if (unlikely(next->es | prev->es))
                 loadsegment(es, next->es); 
-        
-        asm volatile ("mov %%ds,%0" : "=m" (prev->ds));
+
+        savesegment(ds, prev->ds);
         if (unlikely(next->ds | prev->ds))
                 loadsegment(ds, next->ds);
 
+
+        /* We must save %fs and %gs before load_TLS() because
+         * %fs and %gs may be cleared by load_TLS().
+         *
+         * (e.g. xen_load_tls())
+         */
+        savesegment(fs, fsindex);
+        savesegment(gs, gsindex);
+
         load_TLS(next, cpu);
 
+        /*
+         * Leave lazy mode, flushing any hypercalls made here.
+         * This must be done before restoring TLS segments so
+         * the GDT and LDT are properly updated, and must be
+         * done before math_state_restore, so the TS bit is up
+         * to date.
+         */
+        arch_leave_lazy_cpu_mode();
+
         /* 
          * Switch FS and GS.
          */
         { 
-                unsigned fsindex;
-                asm volatile("movl %%fs,%0" : "=r" (fsindex)); 
                 /* segment register != 0 always requires a reload. 
                    also reload when it has changed. 
                    when prev process used 64bit base always reload
@@ -613,10 +605,7 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
                 if (next->fs) 
                         wrmsrl(MSR_FS_BASE, next->fs); 
                 prev->fsindex = fsindex;
-        }
-        { 
-                unsigned gsindex;
-                asm volatile("movl %%gs,%0" : "=r" (gsindex)); 
+
                 if (unlikely(gsindex | next->gsindex | prev->gs)) {
                         load_gs_index(next->gsindex);
                         if (gsindex)
@@ -658,8 +647,11 @@ __switch_to(struct task_struct *prev_p, struct task_struct *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 (next_p->fpu_counter>5)
+        if (tsk_used_math(next_p) && next_p->fpu_counter > 5)
                 math_state_restore();
         return prev_p;
 }
@@ -794,7 +786,7 @@ long do_arch_prctl(struct task_struct *task, int code, unsigned long addr)
                         set_32bit_tls(task, FS_TLS, addr);
                         if (doit) {
                                 load_TLS(&task->thread, cpu);
-                                asm volatile("movl %0,%%fs" :: "r"(FS_TLS_SEL));
+                                loadsegment(fs, FS_TLS_SEL);
                         }
                         task->thread.fsindex = FS_TLS_SEL;
                         task->thread.fs = 0;
@@ -804,7 +796,7 @@ long do_arch_prctl(struct task_struct *task, int code, unsigned long addr)
                         if (doit) {
                                 /* set the selector to 0 to not confuse
                                    __switch_to */
-                                asm volatile("movl %0,%%fs" :: "r" (0));
+                                loadsegment(fs, 0);
                                 ret = checking_wrmsrl(MSR_FS_BASE, addr);
                         }
                 }
@@ -827,7 +819,7 @@ long do_arch_prctl(struct task_struct *task, int code, unsigned long addr)
                 if (task->thread.gsindex == GS_TLS_SEL)
                         base = read_32bit_tls(task, GS_TLS);
                 else if (doit) {
-                        asm("movl %%gs,%0" : "=r" (gsindex));
+                        savesegment(gs, gsindex);
                         if (gsindex)
                                 rdmsrl(MSR_KERNEL_GS_BASE, base);
                         else