Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc-2.6
[linux-2.6] / arch / x86 / kernel / process.c
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>
7 #include <linux/module.h>
8 #include <linux/pm.h>
9
10 struct kmem_cache *task_xstate_cachep;
11
12 int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
13 {
14         *dst = *src;
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         }
23         return 0;
24 }
25
26 void free_thread_xstate(struct task_struct *tsk)
27 {
28         if (tsk->thread.xstate) {
29                 kmem_cache_free(task_xstate_cachep, tsk->thread.xstate);
30                 tsk->thread.xstate = NULL;
31         }
32 }
33
34 void free_thread_info(struct thread_info *ti)
35 {
36         free_thread_xstate(ti->task);
37         free_pages((unsigned long)ti, get_order(THREAD_SIZE));
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 }
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 *)&current_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 *)&current_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
102
103 static int __cpuinit mwait_usable(const struct cpuinfo_x86 *c)
104 {
105         if (force_mwait)
106                 return 1;
107         /* Any C1 states supported? */
108         return c->cpuid_level >= 5 && ((cpuid_edx(5) >> 4) & 0xf) > 0;
109 }
110
111 /*
112  * On SMP it's slightly faster (but much more power-consuming!)
113  * to poll the ->work.need_resched flag instead of waiting for the
114  * cross-CPU IPI to arrive. Use this option with caution.
115  */
116 static void poll_idle(void)
117 {
118         local_irq_enable();
119         cpu_relax();
120 }
121
122 void __cpuinit select_idle_routine(const struct cpuinfo_x86 *c)
123 {
124         static int selected;
125
126         if (selected)
127                 return;
128 #ifdef CONFIG_X86_SMP
129         if (pm_idle == poll_idle && smp_num_siblings > 1) {
130                 printk(KERN_WARNING "WARNING: polling idle and HT enabled,"
131                         " performance may degrade.\n");
132         }
133 #endif
134         if (cpu_has(c, X86_FEATURE_MWAIT) && mwait_usable(c)) {
135                 /*
136                  * Skip, if setup has overridden idle.
137                  * One CPU supports mwait => All CPUs supports mwait
138                  */
139                 if (!pm_idle) {
140                         printk(KERN_INFO "using mwait in idle threads.\n");
141                         pm_idle = mwait_idle;
142                 }
143         }
144         selected = 1;
145 }
146
147 static int __init idle_setup(char *str)
148 {
149         if (!strcmp(str, "poll")) {
150                 printk("using polling idle threads.\n");
151                 pm_idle = poll_idle;
152         } else if (!strcmp(str, "mwait"))
153                 force_mwait = 1;
154         else
155                 return -1;
156
157         boot_option_idle_override = 1;
158         return 0;
159 }
160 early_param("idle", idle_setup);
161