[mirror_ubuntu-artful-kernel.git] / arch / x86 / kernel / process.c

#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <asm/idle.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 <linux/ftrace.h>
#include <asm/system.h>
#include <asm/apic.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()) {
		struct power_trace it;

		trace_power_start(&it, POWER_CSTATE, 1);
		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;
		trace_power_end(&it);
	} else {
		local_irq_enable();
		/* loop is done by the caller */
		cpu_relax();
	}
}
#ifdef CONFIG_APM_MODULE
EXPORT_SYMBOL(default_idle);
#endif

void stop_this_cpu(void *dummy)
{
	local_irq_disable();
	/*
	 * Remove this CPU:
	 */
	cpu_clear(smp_processor_id(), cpu_online_map);
	disable_local_APIC();

	for (;;) {
		if (hlt_works(smp_processor_id()))
			halt();
	}
}

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)
{
	struct power_trace it;

	trace_power_start(&it, POWER_CSTATE, (ax>>4)+1);
	if (!need_resched()) {
		__monitor((void *)&current_thread_info()->flags, 0, 0);
		smp_mb();
		if (!need_resched())
			__mwait(ax, cx);
	}
	trace_power_end(&it);
}

/* Default MONITOR/MWAIT with no hints, used for default C1 state */
static void mwait_idle(void)
{
	struct power_trace it;
	if (!need_resched()) {
		trace_power_start(&it, POWER_CSTATE, 1);
		__monitor((void *)&current_thread_info()->flags, 0, 0);
		smp_mb();
		if (!need_resched())
			__sti_mwait(0, 0);
		else
			local_irq_enable();
		trace_power_end(&it);
	} 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)
{
	struct power_trace it;

	trace_power_start(&it, POWER_CSTATE, 0);
	local_irq_enable();
	while (!need_resched())
		cpu_relax();
	trace_power_end(&it);
}

/*
 * 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_NONSTOP_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);
Commit	Line	Data
61c4628b SS	1	#include <linux/errno.h>
	2	#include <linux/kernel.h>
	3	#include <linux/mm.h>
f0bc2202	4	#include <asm/idle.h>
61c4628b SS	5	#include <linux/smp.h>
	6	#include <linux/slab.h>
	7	#include <linux/sched.h>
7f424a8b PZ	8	#include <linux/module.h>
7f424a8b PZ	9	#include <linux/pm.h>
aa276e1c	10	#include <linux/clockchips.h>
f3f47a67	11	#include <linux/ftrace.h>
c1e3b377	12	#include <asm/system.h>
d3ec5cae	13	#include <asm/apic.h>
c1e3b377 ZY	14
	15	unsigned long idle_halt;
	16	EXPORT_SYMBOL(idle_halt);
da5e09a1 ZY	17	unsigned long idle_nomwait;
da5e09a1 ZY	18	EXPORT_SYMBOL(idle_nomwait);
61c4628b	19
aa283f49	20	struct kmem_cache *task_xstate_cachep;
61c4628b SS	21
	22	int arch_dup_task_struct(struct task_struct dst, struct task_struct src)
	23	{
	24	dst = src;
aa283f49 SS	25	if (src->thread.xstate) {
	26	dst->thread.xstate = kmem_cache_alloc(task_xstate_cachep,
	27	GFP_KERNEL);
	28	if (!dst->thread.xstate)
	29	return -ENOMEM;
	30	WARN_ON((unsigned long)dst->thread.xstate & 15);
	31	memcpy(dst->thread.xstate, src->thread.xstate, xstate_size);
	32	}
61c4628b SS	33	return 0;
	34	}
	35
aa283f49	36	void free_thread_xstate(struct task_struct *tsk)
61c4628b	37	{
aa283f49 SS	38	if (tsk->thread.xstate) {
	39	kmem_cache_free(task_xstate_cachep, tsk->thread.xstate);
	40	tsk->thread.xstate = NULL;
	41	}
	42	}
	43
aa283f49 SS	44	void free_thread_info(struct thread_info *ti)
	45	{
	46	free_thread_xstate(ti->task);
1679f271	47	free_pages((unsigned long)ti, get_order(THREAD_SIZE));
61c4628b SS	48	}
	49
	50	void arch_task_cache_init(void)
	51	{
	52	task_xstate_cachep =
	53	kmem_cache_create("task_xstate", xstate_size,
	54	__alignof__(union thread_xstate),
	55	SLAB_PANIC, NULL);
	56	}
7f424a8b	57
00dba564 TG	58	/*
	59	* Idle related variables and functions
	60	*/
	61	unsigned long boot_option_idle_override = 0;
	62	EXPORT_SYMBOL(boot_option_idle_override);
	63
	64	/*
	65	* Powermanagement idle function, if any..
	66	*/
	67	void (*pm_idle)(void);
	68	EXPORT_SYMBOL(pm_idle);
	69
	70	#ifdef CONFIG_X86_32
	71	/*
	72	* This halt magic was a workaround for ancient floppy DMA
	73	* wreckage. It should be safe to remove.
	74	*/
	75	static int hlt_counter;
	76	void disable_hlt(void)
	77	{
	78	hlt_counter++;
	79	}
	80	EXPORT_SYMBOL(disable_hlt);
	81
	82	void enable_hlt(void)
	83	{
	84	hlt_counter--;
	85	}
	86	EXPORT_SYMBOL(enable_hlt);
	87
	88	static inline int hlt_use_halt(void)
	89	{
	90	return (!hlt_counter && boot_cpu_data.hlt_works_ok);
	91	}
	92	#else
	93	static inline int hlt_use_halt(void)
	94	{
	95	return 1;
	96	}
	97	#endif
	98
	99	/*
	100	* We use this if we don't have any better
	101	* idle routine..
	102	*/
	103	void default_idle(void)
	104	{
	105	if (hlt_use_halt()) {
f3f47a67 AV	106	struct power_trace it;
	107
	108	trace_power_start(&it, POWER_CSTATE, 1);
00dba564 TG	109	current_thread_info()->status &= ~TS_POLLING;
	110	/*
	111	* TS_POLLING-cleared state must be visible before we
	112	* test NEED_RESCHED:
	113	*/
	114	smp_mb();
	115
	116	if (!need_resched())
	117	safe_halt(); /* enables interrupts racelessly */
	118	else
	119	local_irq_enable();
	120	current_thread_info()->status \|= TS_POLLING;
f3f47a67	121	trace_power_end(&it);
00dba564 TG	122	} else {
	123	local_irq_enable();
	124	/* loop is done by the caller */
	125	cpu_relax();
	126	}
	127	}
	128	#ifdef CONFIG_APM_MODULE
	129	EXPORT_SYMBOL(default_idle);
	130	#endif
	131
d3ec5cae IV	132	void stop_this_cpu(void *dummy)
	133	{
	134	local_irq_disable();
	135	/*
	136	* Remove this CPU:
	137	*/
	138	cpu_clear(smp_processor_id(), cpu_online_map);
	139	disable_local_APIC();
	140
	141	for (;;) {
	142	if (hlt_works(smp_processor_id()))
	143	halt();
	144	}
	145	}
	146
7f424a8b PZ	147	static void do_nothing(void *unused)
	148	{
	149	}
	150
	151	/*
	152	* cpu_idle_wait - Used to ensure that all the CPUs discard old value of
	153	* pm_idle and update to new pm_idle value. Required while changing pm_idle
	154	* handler on SMP systems.
	155	*
	156	* Caller must have changed pm_idle to the new value before the call. Old
	157	* pm_idle value will not be used by any CPU after the return of this function.
	158	*/
	159	void cpu_idle_wait(void)
	160	{
	161	smp_mb();
	162	/* kick all the CPUs so that they exit out of pm_idle */
127a237a	163	smp_call_function(do_nothing, NULL, 1);
7f424a8b PZ	164	}
	165	EXPORT_SYMBOL_GPL(cpu_idle_wait);
	166
	167	/*
	168	* This uses new MONITOR/MWAIT instructions on P4 processors with PNI,
	169	* which can obviate IPI to trigger checking of need_resched.
	170	* We execute MONITOR against need_resched and enter optimized wait state
	171	* through MWAIT. Whenever someone changes need_resched, we would be woken
	172	* up from MWAIT (without an IPI).
	173	*
	174	* New with Core Duo processors, MWAIT can take some hints based on CPU
	175	* capability.
	176	*/
	177	void mwait_idle_with_hints(unsigned long ax, unsigned long cx)
	178	{
f3f47a67 AV	179	struct power_trace it;
	180
	181	trace_power_start(&it, POWER_CSTATE, (ax>>4)+1);
7f424a8b PZ	182	if (!need_resched()) {
	183	__monitor((void *)&current_thread_info()->flags, 0, 0);
	184	smp_mb();
	185	if (!need_resched())
	186	__mwait(ax, cx);
	187	}
f3f47a67	188	trace_power_end(&it);
7f424a8b PZ	189	}
	190
	191	/* Default MONITOR/MWAIT with no hints, used for default C1 state */
	192	static void mwait_idle(void)
	193	{
f3f47a67	194	struct power_trace it;
7f424a8b	195	if (!need_resched()) {
f3f47a67	196	trace_power_start(&it, POWER_CSTATE, 1);
7f424a8b PZ	197	__monitor((void *)&current_thread_info()->flags, 0, 0);
	198	smp_mb();
	199	if (!need_resched())
	200	__sti_mwait(0, 0);
	201	else
	202	local_irq_enable();
f3f47a67	203	trace_power_end(&it);
7f424a8b PZ	204	} else
	205	local_irq_enable();
	206	}
	207
7f424a8b PZ	208	/*
	209	* On SMP it's slightly faster (but much more power-consuming!)
	210	* to poll the ->work.need_resched flag instead of waiting for the
	211	* cross-CPU IPI to arrive. Use this option with caution.
	212	*/
	213	static void poll_idle(void)
	214	{
f3f47a67 AV	215	struct power_trace it;
	216
	217	trace_power_start(&it, POWER_CSTATE, 0);
7f424a8b	218	local_irq_enable();
2c7e9fd4 JK	219	while (!need_resched())
2c7e9fd4 JK	220	cpu_relax();
f3f47a67	221	trace_power_end(&it);
7f424a8b PZ	222	}
7f424a8b PZ	223
e9623b35 TG	224	/*
	225	* mwait selection logic:
	226	*
	227	* It depends on the CPU. For AMD CPUs that support MWAIT this is
	228	* wrong. Family 0x10 and 0x11 CPUs will enter C1 on HLT. Powersavings
	229	* then depend on a clock divisor and current Pstate of the core. If
	230	* all cores of a processor are in halt state (C1) the processor can
	231	* enter the C1E (C1 enhanced) state. If mwait is used this will never
	232	* happen.
	233	*
	234	* idle=mwait overrides this decision and forces the usage of mwait.
	235	*/
08ad8afa	236	static int __cpuinitdata force_mwait;
09fd4b4e TG	237
	238	#define MWAIT_INFO 0x05
	239	#define MWAIT_ECX_EXTENDED_INFO 0x01
	240	#define MWAIT_EDX_C1 0xf0
	241
e9623b35 TG	242	static int __cpuinit mwait_usable(const struct cpuinfo_x86 *c)
e9623b35 TG	243	{
09fd4b4e TG	244	u32 eax, ebx, ecx, edx;
09fd4b4e TG	245
e9623b35 TG	246	if (force_mwait)
	247	return 1;
	248
09fd4b4e TG	249	if (c->cpuid_level < MWAIT_INFO)
	250	return 0;
	251
	252	cpuid(MWAIT_INFO, &eax, &ebx, &ecx, &edx);
	253	/* Check, whether EDX has extended info about MWAIT */
	254	if (!(ecx & MWAIT_ECX_EXTENDED_INFO))
	255	return 1;
	256
	257	/*
	258	* edx enumeratios MONITOR/MWAIT extensions. Check, whether
	259	* C1 supports MWAIT
	260	*/
	261	return (edx & MWAIT_EDX_C1);
e9623b35 TG	262	}
e9623b35 TG	263
aa276e1c TG	264	/*
	265	* Check for AMD CPUs, which have potentially C1E support
	266	*/
	267	static int __cpuinit check_c1e_idle(const struct cpuinfo_x86 *c)
	268	{
	269	if (c->x86_vendor != X86_VENDOR_AMD)
	270	return 0;
	271
	272	if (c->x86 < 0x0F)
	273	return 0;
	274
	275	/* Family 0x0f models < rev F do not have C1E */
	276	if (c->x86 == 0x0f && c->x86_model < 0x40)
	277	return 0;
	278
	279	return 1;
	280	}
	281
4faac97d TG	282	static cpumask_t c1e_mask = CPU_MASK_NONE;
	283	static int c1e_detected;
	284
	285	void c1e_remove_cpu(int cpu)
	286	{
	287	cpu_clear(cpu, c1e_mask);
	288	}
	289
aa276e1c TG	290	/*
	291	* C1E aware idle routine. We check for C1E active in the interrupt
	292	* pending message MSR. If we detect C1E, then we handle it the same
	293	* way as C3 power states (local apic timer and TSC stop)
	294	*/
	295	static void c1e_idle(void)
	296	{
aa276e1c TG	297	if (need_resched())
	298	return;
	299
	300	if (!c1e_detected) {
	301	u32 lo, hi;
	302
	303	rdmsr(MSR_K8_INT_PENDING_MSG, lo, hi);
	304	if (lo & K8_INTP_C1E_ACTIVE_MASK) {
	305	c1e_detected = 1;
40fb1715	306	if (!boot_cpu_has(X86_FEATURE_NONSTOP_TSC))
09bfeea1 AH	307	mark_tsc_unstable("TSC halt in AMD C1E");
09bfeea1 AH	308	printk(KERN_INFO "System has AMD C1E enabled\n");
a8d68290	309	set_cpu_cap(&boot_cpu_data, X86_FEATURE_AMDC1E);
aa276e1c TG	310	}
	311	}
	312
	313	if (c1e_detected) {
	314	int cpu = smp_processor_id();
	315
	316	if (!cpu_isset(cpu, c1e_mask)) {
	317	cpu_set(cpu, c1e_mask);
0beefa20 TG	318	/*
	319	* Force broadcast so ACPI can not interfere. Needs
	320	* to run with interrupts enabled as it uses
	321	* smp_function_call.
	322	*/
	323	local_irq_enable();
aa276e1c TG	324	clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_FORCE,
	325	&cpu);
	326	printk(KERN_INFO "Switch to broadcast mode on CPU%d\n",
	327	cpu);
0beefa20	328	local_irq_disable();
aa276e1c TG	329	}
aa276e1c TG	330	clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER, &cpu);
0beefa20	331
aa276e1c	332	default_idle();
0beefa20 TG	333
	334	/*
	335	* The switch back from broadcast mode needs to be
	336	* called with interrupts disabled.
	337	*/
	338	local_irq_disable();
	339	clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_EXIT, &cpu);
	340	local_irq_enable();
aa276e1c TG	341	} else
	342	default_idle();
	343	}
	344
7f424a8b PZ	345	void __cpuinit select_idle_routine(const struct cpuinfo_x86 *c)
7f424a8b PZ	346	{
7f424a8b PZ	347	#ifdef CONFIG_X86_SMP
	348	if (pm_idle == poll_idle && smp_num_siblings > 1) {
	349	printk(KERN_WARNING "WARNING: polling idle and HT enabled,"
	350	" performance may degrade.\n");
	351	}
	352	#endif
6ddd2a27 TG	353	if (pm_idle)
	354	return;
	355
e9623b35	356	if (cpu_has(c, X86_FEATURE_MWAIT) && mwait_usable(c)) {
7f424a8b	357	/*
7f424a8b PZ	358	* One CPU supports mwait => All CPUs supports mwait
7f424a8b PZ	359	*/
6ddd2a27 TG	360	printk(KERN_INFO "using mwait in idle threads.\n");
6ddd2a27 TG	361	pm_idle = mwait_idle;
aa276e1c TG	362	} else if (check_c1e_idle(c)) {
	363	printk(KERN_INFO "using C1E aware idle routine\n");
	364	pm_idle = c1e_idle;
6ddd2a27 TG	365	} else
6ddd2a27 TG	366	pm_idle = default_idle;
7f424a8b PZ	367	}
	368
	369	static int __init idle_setup(char *str)
	370	{
ab6bc3e3 CG	371	if (!str)
	372	return -EINVAL;
	373
7f424a8b PZ	374	if (!strcmp(str, "poll")) {
	375	printk("using polling idle threads.\n");
	376	pm_idle = poll_idle;
	377	} else if (!strcmp(str, "mwait"))
	378	force_mwait = 1;
c1e3b377 ZY	379	else if (!strcmp(str, "halt")) {
	380	/*
	381	* When the boot option of idle=halt is added, halt is
	382	* forced to be used for CPU idle. In such case CPU C2/C3
	383	* won't be used again.
	384	* To continue to load the CPU idle driver, don't touch
	385	* the boot_option_idle_override.
	386	*/
	387	pm_idle = default_idle;
	388	idle_halt = 1;
	389	return 0;
da5e09a1 ZY	390	} else if (!strcmp(str, "nomwait")) {
	391	/*
	392	* If the boot option of "idle=nomwait" is added,
	393	* it means that mwait will be disabled for CPU C2/C3
	394	* states. In such case it won't touch the variable
	395	* of boot_option_idle_override.
	396	*/
	397	idle_nomwait = 1;
	398	return 0;
c1e3b377	399	} else
7f424a8b PZ	400	return -1;
	401
	402	boot_option_idle_override = 1;
	403	return 0;
	404	}
	405	early_param("idle", idle_setup);
	406