1 #include <linux/errno.h>
2 #include <linux/kernel.h>
5 #include <linux/slab.h>
6 #include <linux/sched.h>
7 #include <linux/module.h>
9 #include <linux/clockchips.h>
10 #include <asm/system.h>
12 unsigned long idle_halt
;
13 EXPORT_SYMBOL(idle_halt
);
14 unsigned long idle_nomwait
;
15 EXPORT_SYMBOL(idle_nomwait
);
17 struct kmem_cache
*task_xstate_cachep
;
19 int arch_dup_task_struct(struct task_struct
*dst
, struct task_struct
*src
)
22 if (src
->thread
.xstate
) {
23 dst
->thread
.xstate
= kmem_cache_alloc(task_xstate_cachep
,
25 if (!dst
->thread
.xstate
)
27 WARN_ON((unsigned long)dst
->thread
.xstate
& 15);
28 memcpy(dst
->thread
.xstate
, src
->thread
.xstate
, xstate_size
);
33 void free_thread_xstate(struct task_struct
*tsk
)
35 if (tsk
->thread
.xstate
) {
36 kmem_cache_free(task_xstate_cachep
, tsk
->thread
.xstate
);
37 tsk
->thread
.xstate
= NULL
;
41 void free_thread_info(struct thread_info
*ti
)
43 free_thread_xstate(ti
->task
);
44 free_pages((unsigned long)ti
, get_order(THREAD_SIZE
));
47 void arch_task_cache_init(void)
50 kmem_cache_create("task_xstate", xstate_size
,
51 __alignof__(union thread_xstate
),
56 * Idle related variables and functions
58 unsigned long boot_option_idle_override
= 0;
59 EXPORT_SYMBOL(boot_option_idle_override
);
62 * Powermanagement idle function, if any..
64 void (*pm_idle
)(void);
65 EXPORT_SYMBOL(pm_idle
);
69 * This halt magic was a workaround for ancient floppy DMA
70 * wreckage. It should be safe to remove.
72 static int hlt_counter
;
73 void disable_hlt(void)
77 EXPORT_SYMBOL(disable_hlt
);
83 EXPORT_SYMBOL(enable_hlt
);
85 static inline int hlt_use_halt(void)
87 return (!hlt_counter
&& boot_cpu_data
.hlt_works_ok
);
90 static inline int hlt_use_halt(void)
97 * We use this if we don't have any better
100 void default_idle(void)
102 if (hlt_use_halt()) {
103 current_thread_info()->status
&= ~TS_POLLING
;
105 * TS_POLLING-cleared state must be visible before we
111 safe_halt(); /* enables interrupts racelessly */
114 current_thread_info()->status
|= TS_POLLING
;
117 /* loop is done by the caller */
121 #ifdef CONFIG_APM_MODULE
122 EXPORT_SYMBOL(default_idle
);
125 static void do_nothing(void *unused
)
130 * cpu_idle_wait - Used to ensure that all the CPUs discard old value of
131 * pm_idle and update to new pm_idle value. Required while changing pm_idle
132 * handler on SMP systems.
134 * Caller must have changed pm_idle to the new value before the call. Old
135 * pm_idle value will not be used by any CPU after the return of this function.
137 void cpu_idle_wait(void)
140 /* kick all the CPUs so that they exit out of pm_idle */
141 smp_call_function(do_nothing
, NULL
, 1);
143 EXPORT_SYMBOL_GPL(cpu_idle_wait
);
146 * This uses new MONITOR/MWAIT instructions on P4 processors with PNI,
147 * which can obviate IPI to trigger checking of need_resched.
148 * We execute MONITOR against need_resched and enter optimized wait state
149 * through MWAIT. Whenever someone changes need_resched, we would be woken
150 * up from MWAIT (without an IPI).
152 * New with Core Duo processors, MWAIT can take some hints based on CPU
155 void mwait_idle_with_hints(unsigned long ax
, unsigned long cx
)
157 if (!need_resched()) {
158 __monitor((void *)¤t_thread_info()->flags
, 0, 0);
165 /* Default MONITOR/MWAIT with no hints, used for default C1 state */
166 static void mwait_idle(void)
168 if (!need_resched()) {
169 __monitor((void *)¤t_thread_info()->flags
, 0, 0);
180 * On SMP it's slightly faster (but much more power-consuming!)
181 * to poll the ->work.need_resched flag instead of waiting for the
182 * cross-CPU IPI to arrive. Use this option with caution.
184 static void poll_idle(void)
187 while (!need_resched())
192 * mwait selection logic:
194 * It depends on the CPU. For AMD CPUs that support MWAIT this is
195 * wrong. Family 0x10 and 0x11 CPUs will enter C1 on HLT. Powersavings
196 * then depend on a clock divisor and current Pstate of the core. If
197 * all cores of a processor are in halt state (C1) the processor can
198 * enter the C1E (C1 enhanced) state. If mwait is used this will never
201 * idle=mwait overrides this decision and forces the usage of mwait.
203 static int __cpuinitdata force_mwait
;
205 #define MWAIT_INFO 0x05
206 #define MWAIT_ECX_EXTENDED_INFO 0x01
207 #define MWAIT_EDX_C1 0xf0
209 static int __cpuinit
mwait_usable(const struct cpuinfo_x86
*c
)
211 u32 eax
, ebx
, ecx
, edx
;
216 if (c
->cpuid_level
< MWAIT_INFO
)
219 cpuid(MWAIT_INFO
, &eax
, &ebx
, &ecx
, &edx
);
220 /* Check, whether EDX has extended info about MWAIT */
221 if (!(ecx
& MWAIT_ECX_EXTENDED_INFO
))
225 * edx enumeratios MONITOR/MWAIT extensions. Check, whether
228 return (edx
& MWAIT_EDX_C1
);
232 * Check for AMD CPUs, which have potentially C1E support
234 static int __cpuinit
check_c1e_idle(const struct cpuinfo_x86
*c
)
236 if (c
->x86_vendor
!= X86_VENDOR_AMD
)
242 /* Family 0x0f models < rev F do not have C1E */
243 if (c
->x86
== 0x0f && c
->x86_model
< 0x40)
249 static cpumask_t c1e_mask
= CPU_MASK_NONE
;
250 static int c1e_detected
;
252 void c1e_remove_cpu(int cpu
)
254 cpu_clear(cpu
, c1e_mask
);
258 * C1E aware idle routine. We check for C1E active in the interrupt
259 * pending message MSR. If we detect C1E, then we handle it the same
260 * way as C3 power states (local apic timer and TSC stop)
262 static void c1e_idle(void)
270 rdmsr(MSR_K8_INT_PENDING_MSG
, lo
, hi
);
271 if (lo
& K8_INTP_C1E_ACTIVE_MASK
) {
273 if (!boot_cpu_has(X86_FEATURE_CONSTANT_TSC
))
274 mark_tsc_unstable("TSC halt in AMD C1E");
275 printk(KERN_INFO
"System has AMD C1E enabled\n");
276 set_cpu_cap(&boot_cpu_data
, X86_FEATURE_AMDC1E
);
281 int cpu
= smp_processor_id();
283 if (!cpu_isset(cpu
, c1e_mask
)) {
284 cpu_set(cpu
, c1e_mask
);
286 * Force broadcast so ACPI can not interfere. Needs
287 * to run with interrupts enabled as it uses
291 clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_FORCE
,
293 printk(KERN_INFO
"Switch to broadcast mode on CPU%d\n",
297 clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER
, &cpu
);
302 * The switch back from broadcast mode needs to be
303 * called with interrupts disabled.
306 clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_EXIT
, &cpu
);
312 void __cpuinit
select_idle_routine(const struct cpuinfo_x86
*c
)
314 #ifdef CONFIG_X86_SMP
315 if (pm_idle
== poll_idle
&& smp_num_siblings
> 1) {
316 printk(KERN_WARNING
"WARNING: polling idle and HT enabled,"
317 " performance may degrade.\n");
323 if (cpu_has(c
, X86_FEATURE_MWAIT
) && mwait_usable(c
)) {
325 * One CPU supports mwait => All CPUs supports mwait
327 printk(KERN_INFO
"using mwait in idle threads.\n");
328 pm_idle
= mwait_idle
;
329 } else if (check_c1e_idle(c
)) {
330 printk(KERN_INFO
"using C1E aware idle routine\n");
333 pm_idle
= default_idle
;
336 static int __init
idle_setup(char *str
)
341 if (!strcmp(str
, "poll")) {
342 printk("using polling idle threads.\n");
344 } else if (!strcmp(str
, "mwait"))
346 else if (!strcmp(str
, "halt")) {
348 * When the boot option of idle=halt is added, halt is
349 * forced to be used for CPU idle. In such case CPU C2/C3
350 * won't be used again.
351 * To continue to load the CPU idle driver, don't touch
352 * the boot_option_idle_override.
354 pm_idle
= default_idle
;
357 } else if (!strcmp(str
, "nomwait")) {
359 * If the boot option of "idle=nomwait" is added,
360 * it means that mwait will be disabled for CPU C2/C3
361 * states. In such case it won't touch the variable
362 * of boot_option_idle_override.
369 boot_option_idle_override
= 1;
372 early_param("idle", idle_setup
);