1 files changed, 86 insertions, 16 deletions

diff --git a/arch/i386/kernel/process.c b/arch/i386/kernel/process.c
index c641056233a6..bea304d48cdb 100644
--- a/arch/i386/kernel/process.c
+++ b/arch/i386/kernel/process.c
@@ -38,6 +38,7 @@
 #include <linux/ptrace.h>
 #include <linux/random.h>
 #include <linux/personality.h>
+#include <linux/tick.h>
 
 #include <asm/uaccess.h>
 #include <asm/pgtable.h>
@@ -48,6 +49,7 @@
 #include <asm/i387.h>
 #include <asm/desc.h>
 #include <asm/vm86.h>
+#include <asm/idle.h>
 #ifdef CONFIG_MATH_EMULATION
 #include <asm/math_emu.h>
 #endif
@@ -80,6 +82,42 @@ void (*pm_idle)(void);
 EXPORT_SYMBOL(pm_idle);
 static DEFINE_PER_CPU(unsigned int, cpu_idle_state);
 
+static ATOMIC_NOTIFIER_HEAD(idle_notifier);
+
+void idle_notifier_register(struct notifier_block *n)
+{
+        atomic_notifier_chain_register(&idle_notifier, n);
+}
+
+void idle_notifier_unregister(struct notifier_block *n)
+{
+        atomic_notifier_chain_unregister(&idle_notifier, n);
+}
+
+static DEFINE_PER_CPU(volatile unsigned long, idle_state);
+
+void enter_idle(void)
+{
+        /* needs to be atomic w.r.t. interrupts, not against other CPUs */
+        __set_bit(0, &__get_cpu_var(idle_state));
+        atomic_notifier_call_chain(&idle_notifier, IDLE_START, NULL);
+}
+
+static void __exit_idle(void)
+{
+        /* needs to be atomic w.r.t. interrupts, not against other CPUs */
+        if (__test_and_clear_bit(0, &__get_cpu_var(idle_state)) == 0)
+                return;
+        atomic_notifier_call_chain(&idle_notifier, IDLE_END, NULL);
+}
+
+void exit_idle(void)
+{
+        if (current->pid)
+                return;
+        __exit_idle();
+}
+
 void disable_hlt(void)
 {
         hlt_counter++;
@@ -130,6 +168,7 @@ EXPORT_SYMBOL(default_idle);
  */
 static void poll_idle (void)
 {
+        local_irq_enable();
         cpu_relax();
 }
 
@@ -173,6 +212,7 @@ void cpu_idle(void)
 
         /* endless idle loop with no priority at all */
         while (1) {
+                tick_nohz_stop_sched_tick();
                 while (!need_resched()) {
                         void (*idle)(void);
 
@@ -189,8 +229,18 @@ void cpu_idle(void)
                                 play_dead();
 
                         __get_cpu_var(irq_stat).idle_timestamp = jiffies;
+
+                        /*
+                         * Idle routines should keep interrupts disabled
+                         * from here on, until they go to idle.
+                         * Otherwise, idle callbacks can misfire.
+                         */
+                        local_irq_disable();
+                        enter_idle();
                         idle();
+                        __exit_idle();
                 }
+                tick_nohz_restart_sched_tick();
                 preempt_enable_no_resched();
                 schedule();
                 preempt_disable();
@@ -243,7 +293,11 @@ void mwait_idle_with_hints(unsigned long eax, unsigned long ecx)
                 __monitor((void *)&current_thread_info()->flags, 0, 0);
                 smp_mb();
                 if (!need_resched())
-                        __mwait(eax, ecx);
+                        __sti_mwait(eax, ecx);
+                else
+                        local_irq_enable();
+        } else {
+                local_irq_enable();
         }
 }
 
@@ -308,8 +362,8 @@ void show_regs(struct pt_regs * regs)
                 regs->eax,regs->ebx,regs->ecx,regs->edx);
         printk("ESI: %08lx EDI: %08lx EBP: %08lx",
                 regs->esi, regs->edi, regs->ebp);
-        printk(" DS: %04x ES: %04x GS: %04x\n",
-               0xffff & regs->xds,0xffff & regs->xes, 0xffff & regs->xgs);
+        printk(" DS: %04x ES: %04x FS: %04x\n",
+               0xffff & regs->xds,0xffff & regs->xes, 0xffff & regs->xfs);
 
         cr0 = read_cr0();
         cr2 = read_cr2();
@@ -340,7 +394,7 @@ int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
 
         regs.xds = __USER_DS;
         regs.xes = __USER_DS;
-        regs.xgs = __KERNEL_PDA;
+        regs.xfs = __KERNEL_PDA;
         regs.orig_eax = -1;
         regs.eip = (unsigned long) kernel_thread_helper;
         regs.xcs = __KERNEL_CS | get_kernel_rpl();
@@ -425,7 +479,7 @@ int copy_thread(int nr, unsigned long clone_flags, unsigned long esp,
 
         p->thread.eip = (unsigned long) ret_from_fork;
 
-        savesegment(fs,p->thread.fs);
+        savesegment(gs,p->thread.gs);
 
         tsk = current;
         if (unlikely(test_tsk_thread_flag(tsk, TIF_IO_BITMAP))) {
@@ -501,8 +555,8 @@ void dump_thread(struct pt_regs * regs, struct user * dump)
         dump->regs.eax = regs->eax;
         dump->regs.ds = regs->xds;
         dump->regs.es = regs->xes;
-        savesegment(fs,dump->regs.fs);
-        dump->regs.gs = regs->xgs;
+        dump->regs.fs = regs->xfs;
+        savesegment(gs,dump->regs.gs);
         dump->regs.orig_eax = regs->orig_eax;
         dump->regs.eip = regs->eip;
         dump->regs.cs = regs->xcs;
@@ -653,7 +707,7 @@ struct task_struct fastcall * __switch_to(struct task_struct *prev_p, struct tas
         load_esp0(tss, next);
 
         /*
-         * Save away %fs. No need to save %gs, as it was saved on the
+         * Save away %gs. No need to save %fs, as it was saved on the
          * stack on entry.  No need to save %es and %ds, as those are
          * always kernel segments while inside the kernel.  Doing this
          * before setting the new TLS descriptors avoids the situation
@@ -662,7 +716,7 @@ struct task_struct fastcall * __switch_to(struct task_struct *prev_p, struct tas
          * used %fs or %gs (it does not today), or if the kernel is
          * running inside of a hypervisor layer.
          */
-        savesegment(fs, prev->fs);
+        savesegment(gs, prev->gs);
 
         /*
          * Load the per-thread Thread-Local Storage descriptor.
@@ -670,14 +724,13 @@ struct task_struct fastcall * __switch_to(struct task_struct *prev_p, struct tas
         load_TLS(next, cpu);
 
         /*
-         * Restore %fs if needed.
-         *
-         * Glibc normally makes %fs be zero.
+         * Restore IOPL if needed.  In normal use, the flags restore
+         * in the switch assembly will handle this.  But if the kernel
+         * is running virtualized at a non-zero CPL, the popf will
+         * not restore flags, so it must be done in a separate step.
          */
-        if (unlikely(prev->fs | next->fs))
-                loadsegment(fs, next->fs);
-
-        write_pda(pcurrent, next_p);
+        if (get_kernel_rpl() && unlikely(prev->iopl != next->iopl))
+                set_iopl_mask(next->iopl);
 
         /*
          * Now maybe handle debug registers and/or IO bitmaps
@@ -688,6 +741,15 @@ struct task_struct fastcall * __switch_to(struct task_struct *prev_p, struct tas
 
         disable_tsc(prev_p, next_p);
 
+        /*
+         * 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();
+
         /* 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
@@ -695,6 +757,14 @@ struct task_struct fastcall * __switch_to(struct task_struct *prev_p, struct tas
         if (next_p->fpu_counter > 5)
                 math_state_restore();
 
+        /*
+         * Restore %gs if needed (which is common)
+         */
+        if (prev->gs | next->gs)
+                loadsegment(gs, next->gs);
+
+        write_pda(pcurrent, next_p);
+
         return prev_p;
 }