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61c4628b SS |
1 | #include <linux/errno.h> |
2 | #include <linux/kernel.h> | |
3 | #include <linux/mm.h> | |
4 | #include <linux/smp.h> | |
5 | #include <linux/slab.h> | |
6 | #include <linux/sched.h> | |
7f424a8b PZ |
7 | #include <linux/module.h> |
8 | #include <linux/pm.h> | |
61c4628b | 9 | |
aa283f49 | 10 | struct kmem_cache *task_xstate_cachep; |
61c4628b SS |
11 | |
12 | int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src) | |
13 | { | |
14 | *dst = *src; | |
aa283f49 SS |
15 | if (src->thread.xstate) { |
16 | dst->thread.xstate = kmem_cache_alloc(task_xstate_cachep, | |
17 | GFP_KERNEL); | |
18 | if (!dst->thread.xstate) | |
19 | return -ENOMEM; | |
20 | WARN_ON((unsigned long)dst->thread.xstate & 15); | |
21 | memcpy(dst->thread.xstate, src->thread.xstate, xstate_size); | |
22 | } | |
61c4628b SS |
23 | return 0; |
24 | } | |
25 | ||
aa283f49 | 26 | void free_thread_xstate(struct task_struct *tsk) |
61c4628b | 27 | { |
aa283f49 SS |
28 | if (tsk->thread.xstate) { |
29 | kmem_cache_free(task_xstate_cachep, tsk->thread.xstate); | |
30 | tsk->thread.xstate = NULL; | |
31 | } | |
32 | } | |
33 | ||
aa283f49 SS |
34 | void free_thread_info(struct thread_info *ti) |
35 | { | |
36 | free_thread_xstate(ti->task); | |
1679f271 | 37 | free_pages((unsigned long)ti, get_order(THREAD_SIZE)); |
61c4628b SS |
38 | } |
39 | ||
40 | void arch_task_cache_init(void) | |
41 | { | |
42 | task_xstate_cachep = | |
43 | kmem_cache_create("task_xstate", xstate_size, | |
44 | __alignof__(union thread_xstate), | |
45 | SLAB_PANIC, NULL); | |
46 | } | |
7f424a8b PZ |
47 | |
48 | static void do_nothing(void *unused) | |
49 | { | |
50 | } | |
51 | ||
52 | /* | |
53 | * cpu_idle_wait - Used to ensure that all the CPUs discard old value of | |
54 | * pm_idle and update to new pm_idle value. Required while changing pm_idle | |
55 | * handler on SMP systems. | |
56 | * | |
57 | * Caller must have changed pm_idle to the new value before the call. Old | |
58 | * pm_idle value will not be used by any CPU after the return of this function. | |
59 | */ | |
60 | void cpu_idle_wait(void) | |
61 | { | |
62 | smp_mb(); | |
63 | /* kick all the CPUs so that they exit out of pm_idle */ | |
64 | smp_call_function(do_nothing, NULL, 0, 1); | |
65 | } | |
66 | EXPORT_SYMBOL_GPL(cpu_idle_wait); | |
67 | ||
68 | /* | |
69 | * This uses new MONITOR/MWAIT instructions on P4 processors with PNI, | |
70 | * which can obviate IPI to trigger checking of need_resched. | |
71 | * We execute MONITOR against need_resched and enter optimized wait state | |
72 | * through MWAIT. Whenever someone changes need_resched, we would be woken | |
73 | * up from MWAIT (without an IPI). | |
74 | * | |
75 | * New with Core Duo processors, MWAIT can take some hints based on CPU | |
76 | * capability. | |
77 | */ | |
78 | void mwait_idle_with_hints(unsigned long ax, unsigned long cx) | |
79 | { | |
80 | if (!need_resched()) { | |
81 | __monitor((void *)¤t_thread_info()->flags, 0, 0); | |
82 | smp_mb(); | |
83 | if (!need_resched()) | |
84 | __mwait(ax, cx); | |
85 | } | |
86 | } | |
87 | ||
88 | /* Default MONITOR/MWAIT with no hints, used for default C1 state */ | |
89 | static void mwait_idle(void) | |
90 | { | |
91 | if (!need_resched()) { | |
92 | __monitor((void *)¤t_thread_info()->flags, 0, 0); | |
93 | smp_mb(); | |
94 | if (!need_resched()) | |
95 | __sti_mwait(0, 0); | |
96 | else | |
97 | local_irq_enable(); | |
98 | } else | |
99 | local_irq_enable(); | |
100 | } | |
101 | ||
7f424a8b PZ |
102 | /* |
103 | * On SMP it's slightly faster (but much more power-consuming!) | |
104 | * to poll the ->work.need_resched flag instead of waiting for the | |
105 | * cross-CPU IPI to arrive. Use this option with caution. | |
106 | */ | |
107 | static void poll_idle(void) | |
108 | { | |
109 | local_irq_enable(); | |
110 | cpu_relax(); | |
111 | } | |
112 | ||
113 | void __cpuinit select_idle_routine(const struct cpuinfo_x86 *c) | |
114 | { | |
115 | static int selected; | |
116 | ||
117 | if (selected) | |
118 | return; | |
119 | #ifdef CONFIG_X86_SMP | |
120 | if (pm_idle == poll_idle && smp_num_siblings > 1) { | |
121 | printk(KERN_WARNING "WARNING: polling idle and HT enabled," | |
122 | " performance may degrade.\n"); | |
123 | } | |
124 | #endif | |
a738d897 | 125 | if (cpu_has(c, X86_FEATURE_MWAIT)) { |
7f424a8b PZ |
126 | /* |
127 | * Skip, if setup has overridden idle. | |
128 | * One CPU supports mwait => All CPUs supports mwait | |
129 | */ | |
130 | if (!pm_idle) { | |
131 | printk(KERN_INFO "using mwait in idle threads.\n"); | |
132 | pm_idle = mwait_idle; | |
133 | } | |
134 | } | |
135 | selected = 1; | |
136 | } | |
137 | ||
138 | static int __init idle_setup(char *str) | |
139 | { | |
140 | if (!strcmp(str, "poll")) { | |
141 | printk("using polling idle threads.\n"); | |
142 | pm_idle = poll_idle; | |
143 | } else if (!strcmp(str, "mwait")) | |
144 | force_mwait = 1; | |
145 | else | |
146 | return -1; | |
147 | ||
148 | boot_option_idle_override = 1; | |
149 | return 0; | |
150 | } | |
151 | early_param("idle", idle_setup); | |
152 |