#include <linux/errno.h> #include <linux/kernel.h> #include <linux/mm.h> #include <linux/smp.h> #include <linux/slab.h> #include <linux/sched.h> #include <linux/module.h> #include <linux/pm.h> #include <linux/clockchips.h> #include <asm/system.h> unsigned long idle_halt; EXPORT_SYMBOL(idle_halt); unsigned long idle_nomwait; EXPORT_SYMBOL(idle_nomwait); struct kmem_cache *task_xstate_cachep; int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src) { *dst = *src; if (src->thread.xstate) { dst->thread.xstate = kmem_cache_alloc(task_xstate_cachep, GFP_KERNEL); if (!dst->thread.xstate) return -ENOMEM; WARN_ON((unsigned long)dst->thread.xstate & 15); memcpy(dst->thread.xstate, src->thread.xstate, xstate_size); } return 0; } void free_thread_xstate(struct task_struct *tsk) { if (tsk->thread.xstate) { kmem_cache_free(task_xstate_cachep, tsk->thread.xstate); tsk->thread.xstate = NULL; } } void free_thread_info(struct thread_info *ti) { free_thread_xstate(ti->task); free_pages((unsigned long)ti, get_order(THREAD_SIZE)); } void arch_task_cache_init(void) { task_xstate_cachep = kmem_cache_create("task_xstate", xstate_size, __alignof__(union thread_xstate), SLAB_PANIC, NULL); } /* * Idle related variables and functions */ 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); #ifdef CONFIG_X86_32 /* * This halt magic was a workaround for ancient floppy DMA * wreckage. It should be safe to remove. */ static int hlt_counter; void disable_hlt(void) { hlt_counter++; } EXPORT_SYMBOL(disable_hlt); void enable_hlt(void) { hlt_counter--; } EXPORT_SYMBOL(enable_hlt); static inline int hlt_use_halt(void) { return (!hlt_counter && boot_cpu_data.hlt_works_ok); } #else static inline int hlt_use_halt(void) { return 1; } #endif /* * We use this if we don't have any better * idle routine.. */ void default_idle(void) { if (hlt_use_halt()) { 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; } else { local_irq_enable(); /* loop is done by the caller */ cpu_relax(); } } #ifdef CONFIG_APM_MODULE EXPORT_SYMBOL(default_idle); #endif static void do_nothing(void *unused) { } /* * cpu_idle_wait - Used to ensure that all the CPUs discard old value of * pm_idle and update to new pm_idle value. Required while changing pm_idle * handler on SMP systems. * * Caller must have changed pm_idle to the new value before the call. Old * pm_idle value will not be used by any CPU after the return of this function. */ void cpu_idle_wait(void) { smp_mb(); /* kick all the CPUs so that they exit out of pm_idle */ smp_call_function(do_nothing, NULL, 1); } EXPORT_SYMBOL_GPL(cpu_idle_wait); /* * This uses new MONITOR/MWAIT instructions on P4 processors with PNI, * which can obviate IPI to trigger checking of need_resched. * We execute MONITOR against need_resched and enter optimized wait state * through MWAIT. Whenever someone changes need_resched, we would be woken * up from MWAIT (without an IPI). * * New with Core Duo processors, MWAIT can take some hints based on CPU * capability. */ void mwait_idle_with_hints(unsigned long ax, unsigned long cx) { if (!need_resched()) { __monitor((void *)¤t_thread_info()->flags, 0, 0); smp_mb(); if (!need_resched()) __mwait(ax, cx); } } /* Default MONITOR/MWAIT with no hints, used for default C1 state */ static void mwait_idle(void) { if (!need_resched()) { __monitor((void *)¤t_thread_info()->flags, 0, 0); smp_mb(); if (!need_resched()) __sti_mwait(0, 0); else local_irq_enable(); } else local_irq_enable(); } /* * On SMP it's slightly faster (but much more power-consuming!) * to poll the ->work.need_resched flag instead of waiting for the * cross-CPU IPI to arrive. Use this option with caution. */ static void poll_idle(void) { local_irq_enable(); while (!need_resched()) cpu_relax(); } /* * mwait selection logic: * * It depends on the CPU. For AMD CPUs that support MWAIT this is * wrong. Family 0x10 and 0x11 CPUs will enter C1 on HLT. Powersavings * then depend on a clock divisor and current Pstate of the core. If * all cores of a processor are in halt state (C1) the processor can * enter the C1E (C1 enhanced) state. If mwait is used this will never * happen. * * idle=mwait overrides this decision and forces the usage of mwait. */ static int __cpuinitdata force_mwait; #define MWAIT_INFO 0x05 #define MWAIT_ECX_EXTENDED_INFO 0x01 #define MWAIT_EDX_C1 0xf0 static int __cpuinit mwait_usable(const struct cpuinfo_x86 *c) { u32 eax, ebx, ecx, edx; if (force_mwait) return 1; if (c->cpuid_level < MWAIT_INFO) return 0; cpuid(MWAIT_INFO, &eax, &ebx, &ecx, &edx); /* Check, whether EDX has extended info about MWAIT */ if (!(ecx & MWAIT_ECX_EXTENDED_INFO)) return 1; /* * edx enumeratios MONITOR/MWAIT extensions. Check, whether * C1 supports MWAIT */ return (edx & MWAIT_EDX_C1); } /* * Check for AMD CPUs, which have potentially C1E support */ static int __cpuinit check_c1e_idle(const struct cpuinfo_x86 *c) { if (c->x86_vendor != X86_VENDOR_AMD) return 0; if (c->x86 < 0x0F) return 0; /* Family 0x0f models < rev F do not have C1E */ if (c->x86 == 0x0f && c->x86_model < 0x40) return 0; return 1; } static cpumask_t c1e_mask = CPU_MASK_NONE; static int c1e_detected; void c1e_remove_cpu(int cpu) { cpu_clear(cpu, c1e_mask); } /* * C1E aware idle routine. We check for C1E active in the interrupt * pending message MSR. If we detect C1E, then we handle it the same * way as C3 power states (local apic timer and TSC stop) */ static void c1e_idle(void) { if (need_resched()) return; if (!c1e_detected) { u32 lo, hi; rdmsr(MSR_K8_INT_PENDING_MSG, lo, hi); if (lo & K8_INTP_C1E_ACTIVE_MASK) { c1e_detected = 1; if (!boot_cpu_has(X86_FEATURE_CONSTANT_TSC)) mark_tsc_unstable("TSC halt in AMD C1E"); printk(KERN_INFO "System has AMD C1E enabled\n"); set_cpu_cap(&boot_cpu_data, X86_FEATURE_AMDC1E); } } if (c1e_detected) { int cpu = smp_processor_id(); if (!cpu_isset(cpu, c1e_mask)) { cpu_set(cpu, c1e_mask); /* * Force broadcast so ACPI can not interfere. Needs * to run with interrupts enabled as it uses * smp_function_call. */ local_irq_enable(); clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_FORCE, &cpu); printk(KERN_INFO "Switch to broadcast mode on CPU%d\n", cpu); local_irq_disable(); } clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER, &cpu); default_idle(); /* * The switch back from broadcast mode needs to be * called with interrupts disabled. */ local_irq_disable(); clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_EXIT, &cpu); local_irq_enable(); } else default_idle(); } void __cpuinit select_idle_routine(const struct cpuinfo_x86 *c) { #ifdef CONFIG_X86_SMP if (pm_idle == poll_idle && smp_num_siblings > 1) { printk(KERN_WARNING "WARNING: polling idle and HT enabled," " performance may degrade.\n"); } #endif if (pm_idle) return; if (cpu_has(c, X86_FEATURE_MWAIT) && mwait_usable(c)) { /* * One CPU supports mwait => All CPUs supports mwait */ printk(KERN_INFO "using mwait in idle threads.\n"); pm_idle = mwait_idle; } else if (check_c1e_idle(c)) { printk(KERN_INFO "using C1E aware idle routine\n"); pm_idle = c1e_idle; } else pm_idle = default_idle; } static int __init idle_setup(char *str) { if (!str) return -EINVAL; if (!strcmp(str, "poll")) { printk("using polling idle threads.\n"); pm_idle = poll_idle; } else if (!strcmp(str, "mwait")) force_mwait = 1; else if (!strcmp(str, "halt")) { /* * When the boot option of idle=halt is added, halt is * forced to be used for CPU idle. In such case CPU C2/C3 * won't be used again. * To continue to load the CPU idle driver, don't touch * the boot_option_idle_override. */ pm_idle = default_idle; idle_halt = 1; return 0; } else if (!strcmp(str, "nomwait")) { /* * If the boot option of "idle=nomwait" is added, * it means that mwait will be disabled for CPU C2/C3 * states. In such case it won't touch the variable * of boot_option_idle_override. */ idle_nomwait = 1; return 0; } else return -1; boot_option_idle_override = 1; return 0; } early_param("idle", idle_setup);