diff options
Diffstat (limited to 'arch/i386/kernel/process.c')
| -rw-r--r-- | arch/i386/kernel/process.c | 88 |
1 files changed, 43 insertions, 45 deletions
diff --git a/arch/i386/kernel/process.c b/arch/i386/kernel/process.c index dd53c58f64f..c641056233a 100644 --- a/arch/i386/kernel/process.c +++ b/arch/i386/kernel/process.c @@ -56,6 +56,7 @@ #include <asm/tlbflush.h> #include <asm/cpu.h> +#include <asm/pda.h> asmlinkage void ret_from_fork(void) __asm__("ret_from_fork"); @@ -99,22 +100,23 @@ EXPORT_SYMBOL(enable_hlt); */ void default_idle(void) { - local_irq_enable(); - if (!hlt_counter && boot_cpu_data.hlt_works_ok) { current_thread_info()->status &= ~TS_POLLING; - smp_mb__after_clear_bit(); - while (!need_resched()) { - local_irq_disable(); - if (!need_resched()) - safe_halt(); - else - local_irq_enable(); - } + /* + * TS_POLLING-cleared state must be visible before we + * test NEED_RESCHED: + */ + smp_mb(); + + local_irq_disable(); + if (!need_resched()) + safe_halt(); /* enables interrupts racelessly */ + else + local_irq_enable(); current_thread_info()->status |= TS_POLLING; } else { - while (!need_resched()) - cpu_relax(); + /* loop is done by the caller */ + cpu_relax(); } } #ifdef CONFIG_APM_MODULE @@ -128,14 +130,7 @@ EXPORT_SYMBOL(default_idle); */ static void poll_idle (void) { - local_irq_enable(); - - asm volatile( - "2:" - "testl %0, %1;" - "rep; nop;" - "je 2b;" - : : "i"(_TIF_NEED_RESCHED), "m" (current_thread_info()->flags)); + cpu_relax(); } #ifdef CONFIG_HOTPLUG_CPU @@ -256,8 +251,7 @@ void mwait_idle_with_hints(unsigned long eax, unsigned long ecx) static void mwait_idle(void) { local_irq_enable(); - while (!need_resched()) - mwait_idle_with_hints(0, 0); + mwait_idle_with_hints(0, 0); } void __devinit select_idle_routine(const struct cpuinfo_x86 *c) @@ -314,8 +308,8 @@ 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\n", - 0xffff & regs->xds,0xffff & regs->xes); + printk(" DS: %04x ES: %04x GS: %04x\n", + 0xffff & regs->xds,0xffff & regs->xes, 0xffff & regs->xgs); cr0 = read_cr0(); cr2 = read_cr2(); @@ -346,6 +340,7 @@ int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags) regs.xds = __USER_DS; regs.xes = __USER_DS; + regs.xgs = __KERNEL_PDA; regs.orig_eax = -1; regs.eip = (unsigned long) kernel_thread_helper; regs.xcs = __KERNEL_CS | get_kernel_rpl(); @@ -431,7 +426,6 @@ 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))) { @@ -508,7 +502,7 @@ void dump_thread(struct pt_regs * regs, struct user * dump) dump->regs.ds = regs->xds; dump->regs.es = regs->xes; savesegment(fs,dump->regs.fs); - savesegment(gs,dump->regs.gs); + dump->regs.gs = regs->xgs; dump->regs.orig_eax = regs->orig_eax; dump->regs.eip = regs->eip; dump->regs.cs = regs->xcs; @@ -648,22 +642,27 @@ struct task_struct fastcall * __switch_to(struct task_struct *prev_p, struct tas __unlazy_fpu(prev_p); + + /* we're going to use this soon, after a few expensive things */ + if (next_p->fpu_counter > 5) + prefetch(&next->i387.fxsave); + /* * Reload esp0. */ load_esp0(tss, next); /* - * Save away %fs and %gs. 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 where we temporarily have non-reloadable - * segments in %fs and %gs. This could be an issue if the - * NMI handler ever used %fs or %gs (it does not today), or - * if the kernel is running inside of a hypervisor layer. + * Save away %fs. No need to save %gs, 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 + * where we temporarily have non-reloadable segments in %fs + * and %gs. This could be an issue if the NMI handler ever + * 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. @@ -671,22 +670,14 @@ struct task_struct fastcall * __switch_to(struct task_struct *prev_p, struct tas load_TLS(next, cpu); /* - * Restore %fs and %gs if needed. + * Restore %fs if needed. * - * Glibc normally makes %fs be zero, and %gs is one of - * the TLS segments. + * Glibc normally makes %fs be zero. */ if (unlikely(prev->fs | next->fs)) loadsegment(fs, next->fs); - if (prev->gs | next->gs) - loadsegment(gs, next->gs); - - /* - * Restore IOPL if needed. - */ - if (unlikely(prev->iopl != next->iopl)) - set_iopl_mask(next->iopl); + write_pda(pcurrent, next_p); /* * Now maybe handle debug registers and/or IO bitmaps @@ -697,6 +688,13 @@ struct task_struct fastcall * __switch_to(struct task_struct *prev_p, struct tas disable_tsc(prev_p, 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 + */ + if (next_p->fpu_counter > 5) + math_state_restore(); + return prev_p; } |