nohz: prevent tick stop outside of the idle loop
[linux-2.6.git] / arch / arm / kernel / process.c
1 /*
2  *  linux/arch/arm/kernel/process.c
3  *
4  *  Copyright (C) 1996-2000 Russell King - Converted to ARM.
5  *  Original Copyright (C) 1995  Linus Torvalds
6  *
7  * This program is free software; you can redistribute it and/or modify
8  * it under the terms of the GNU General Public License version 2 as
9  * published by the Free Software Foundation.
10  */
11 #include <stdarg.h>
12
13 #include <linux/module.h>
14 #include <linux/sched.h>
15 #include <linux/kernel.h>
16 #include <linux/mm.h>
17 #include <linux/stddef.h>
18 #include <linux/unistd.h>
19 #include <linux/slab.h>
20 #include <linux/user.h>
21 #include <linux/delay.h>
22 #include <linux/reboot.h>
23 #include <linux/interrupt.h>
24 #include <linux/kallsyms.h>
25 #include <linux/init.h>
26 #include <linux/cpu.h>
27 #include <linux/elfcore.h>
28 #include <linux/pm.h>
29 #include <linux/tick.h>
30 #include <linux/utsname.h>
31
32 #include <asm/leds.h>
33 #include <asm/processor.h>
34 #include <asm/system.h>
35 #include <asm/thread_notify.h>
36 #include <asm/uaccess.h>
37 #include <asm/mach/time.h>
38
39 static const char *processor_modes[] = {
40   "USER_26", "FIQ_26" , "IRQ_26" , "SVC_26" , "UK4_26" , "UK5_26" , "UK6_26" , "UK7_26" ,
41   "UK8_26" , "UK9_26" , "UK10_26", "UK11_26", "UK12_26", "UK13_26", "UK14_26", "UK15_26",
42   "USER_32", "FIQ_32" , "IRQ_32" , "SVC_32" , "UK4_32" , "UK5_32" , "UK6_32" , "ABT_32" ,
43   "UK8_32" , "UK9_32" , "UK10_32", "UND_32" , "UK12_32", "UK13_32", "UK14_32", "SYS_32"
44 };
45
46 static const char *isa_modes[] = {
47   "ARM" , "Thumb" , "Jazelle", "ThumbEE"
48 };
49
50 extern void setup_mm_for_reboot(char mode);
51
52 static volatile int hlt_counter;
53
54 #include <asm/arch/system.h>
55
56 void disable_hlt(void)
57 {
58         hlt_counter++;
59 }
60
61 EXPORT_SYMBOL(disable_hlt);
62
63 void enable_hlt(void)
64 {
65         hlt_counter--;
66 }
67
68 EXPORT_SYMBOL(enable_hlt);
69
70 static int __init nohlt_setup(char *__unused)
71 {
72         hlt_counter = 1;
73         return 1;
74 }
75
76 static int __init hlt_setup(char *__unused)
77 {
78         hlt_counter = 0;
79         return 1;
80 }
81
82 __setup("nohlt", nohlt_setup);
83 __setup("hlt", hlt_setup);
84
85 void arm_machine_restart(char mode)
86 {
87         /*
88          * Clean and disable cache, and turn off interrupts
89          */
90         cpu_proc_fin();
91
92         /*
93          * Tell the mm system that we are going to reboot -
94          * we may need it to insert some 1:1 mappings so that
95          * soft boot works.
96          */
97         setup_mm_for_reboot(mode);
98
99         /*
100          * Now call the architecture specific reboot code.
101          */
102         arch_reset(mode);
103
104         /*
105          * Whoops - the architecture was unable to reboot.
106          * Tell the user!
107          */
108         mdelay(1000);
109         printk("Reboot failed -- System halted\n");
110         while (1);
111 }
112
113 /*
114  * Function pointers to optional machine specific functions
115  */
116 void (*pm_idle)(void);
117 EXPORT_SYMBOL(pm_idle);
118
119 void (*pm_power_off)(void);
120 EXPORT_SYMBOL(pm_power_off);
121
122 void (*arm_pm_restart)(char str) = arm_machine_restart;
123 EXPORT_SYMBOL_GPL(arm_pm_restart);
124
125
126 /*
127  * This is our default idle handler.  We need to disable
128  * interrupts here to ensure we don't miss a wakeup call.
129  */
130 static void default_idle(void)
131 {
132         if (hlt_counter)
133                 cpu_relax();
134         else {
135                 local_irq_disable();
136                 if (!need_resched()) {
137                         timer_dyn_reprogram();
138                         arch_idle();
139                 }
140                 local_irq_enable();
141         }
142 }
143
144 /*
145  * The idle thread.  We try to conserve power, while trying to keep
146  * overall latency low.  The architecture specific idle is passed
147  * a value to indicate the level of "idleness" of the system.
148  */
149 void cpu_idle(void)
150 {
151         local_fiq_enable();
152
153         /* endless idle loop with no priority at all */
154         while (1) {
155                 void (*idle)(void) = pm_idle;
156
157 #ifdef CONFIG_HOTPLUG_CPU
158                 if (cpu_is_offline(smp_processor_id())) {
159                         leds_event(led_idle_start);
160                         cpu_die();
161                 }
162 #endif
163
164                 if (!idle)
165                         idle = default_idle;
166                 leds_event(led_idle_start);
167                 tick_nohz_stop_sched_tick(1);
168                 while (!need_resched())
169                         idle();
170                 leds_event(led_idle_end);
171                 tick_nohz_restart_sched_tick();
172                 preempt_enable_no_resched();
173                 schedule();
174                 preempt_disable();
175         }
176 }
177
178 static char reboot_mode = 'h';
179
180 int __init reboot_setup(char *str)
181 {
182         reboot_mode = str[0];
183         return 1;
184 }
185
186 __setup("reboot=", reboot_setup);
187
188 void machine_halt(void)
189 {
190 }
191
192
193 void machine_power_off(void)
194 {
195         if (pm_power_off)
196                 pm_power_off();
197 }
198
199 void machine_restart(char * __unused)
200 {
201         arm_pm_restart(reboot_mode);
202 }
203
204 void __show_regs(struct pt_regs *regs)
205 {
206         unsigned long flags;
207         char buf[64];
208
209         printk("CPU: %d    %s  (%s %.*s)\n",
210                 smp_processor_id(), print_tainted(), init_utsname()->release,
211                 (int)strcspn(init_utsname()->version, " "),
212                 init_utsname()->version);
213         print_symbol("PC is at %s\n", instruction_pointer(regs));
214         print_symbol("LR is at %s\n", regs->ARM_lr);
215         printk("pc : [<%08lx>]    lr : [<%08lx>]    psr: %08lx\n"
216                "sp : %08lx  ip : %08lx  fp : %08lx\n",
217                 regs->ARM_pc, regs->ARM_lr, regs->ARM_cpsr,
218                 regs->ARM_sp, regs->ARM_ip, regs->ARM_fp);
219         printk("r10: %08lx  r9 : %08lx  r8 : %08lx\n",
220                 regs->ARM_r10, regs->ARM_r9,
221                 regs->ARM_r8);
222         printk("r7 : %08lx  r6 : %08lx  r5 : %08lx  r4 : %08lx\n",
223                 regs->ARM_r7, regs->ARM_r6,
224                 regs->ARM_r5, regs->ARM_r4);
225         printk("r3 : %08lx  r2 : %08lx  r1 : %08lx  r0 : %08lx\n",
226                 regs->ARM_r3, regs->ARM_r2,
227                 regs->ARM_r1, regs->ARM_r0);
228
229         flags = regs->ARM_cpsr;
230         buf[0] = flags & PSR_N_BIT ? 'N' : 'n';
231         buf[1] = flags & PSR_Z_BIT ? 'Z' : 'z';
232         buf[2] = flags & PSR_C_BIT ? 'C' : 'c';
233         buf[3] = flags & PSR_V_BIT ? 'V' : 'v';
234         buf[4] = '\0';
235
236         printk("Flags: %s  IRQs o%s  FIQs o%s  Mode %s  ISA %s  Segment %s\n",
237                 buf, interrupts_enabled(regs) ? "n" : "ff",
238                 fast_interrupts_enabled(regs) ? "n" : "ff",
239                 processor_modes[processor_mode(regs)],
240                 isa_modes[isa_mode(regs)],
241                 get_fs() == get_ds() ? "kernel" : "user");
242 #ifdef CONFIG_CPU_CP15
243         {
244                 unsigned int ctrl;
245
246                 buf[0] = '\0';
247 #ifdef CONFIG_CPU_CP15_MMU
248                 {
249                         unsigned int transbase, dac;
250                         asm("mrc p15, 0, %0, c2, c0\n\t"
251                             "mrc p15, 0, %1, c3, c0\n"
252                             : "=r" (transbase), "=r" (dac));
253                         snprintf(buf, sizeof(buf), "  Table: %08x  DAC: %08x",
254                                 transbase, dac);
255                 }
256 #endif
257                 asm("mrc p15, 0, %0, c1, c0\n" : "=r" (ctrl));
258
259                 printk("Control: %08x%s\n", ctrl, buf);
260         }
261 #endif
262 }
263
264 void show_regs(struct pt_regs * regs)
265 {
266         printk("\n");
267         printk("Pid: %d, comm: %20s\n", task_pid_nr(current), current->comm);
268         __show_regs(regs);
269         __backtrace();
270 }
271
272 void show_fpregs(struct user_fp *regs)
273 {
274         int i;
275
276         for (i = 0; i < 8; i++) {
277                 unsigned long *p;
278                 char type;
279
280                 p = (unsigned long *)(regs->fpregs + i);
281
282                 switch (regs->ftype[i]) {
283                         case 1: type = 'f'; break;
284                         case 2: type = 'd'; break;
285                         case 3: type = 'e'; break;
286                         default: type = '?'; break;
287                 }
288                 if (regs->init_flag)
289                         type = '?';
290
291                 printk("  f%d(%c): %08lx %08lx %08lx%c",
292                         i, type, p[0], p[1], p[2], i & 1 ? '\n' : ' ');
293         }
294                         
295
296         printk("FPSR: %08lx FPCR: %08lx\n",
297                 (unsigned long)regs->fpsr,
298                 (unsigned long)regs->fpcr);
299 }
300
301 /*
302  * Free current thread data structures etc..
303  */
304 void exit_thread(void)
305 {
306 }
307
308 ATOMIC_NOTIFIER_HEAD(thread_notify_head);
309
310 EXPORT_SYMBOL_GPL(thread_notify_head);
311
312 void flush_thread(void)
313 {
314         struct thread_info *thread = current_thread_info();
315         struct task_struct *tsk = current;
316
317         memset(thread->used_cp, 0, sizeof(thread->used_cp));
318         memset(&tsk->thread.debug, 0, sizeof(struct debug_info));
319         memset(&thread->fpstate, 0, sizeof(union fp_state));
320
321         thread_notify(THREAD_NOTIFY_FLUSH, thread);
322 }
323
324 void release_thread(struct task_struct *dead_task)
325 {
326         struct thread_info *thread = task_thread_info(dead_task);
327
328         thread_notify(THREAD_NOTIFY_RELEASE, thread);
329 }
330
331 asmlinkage void ret_from_fork(void) __asm__("ret_from_fork");
332
333 int
334 copy_thread(int nr, unsigned long clone_flags, unsigned long stack_start,
335             unsigned long stk_sz, struct task_struct *p, struct pt_regs *regs)
336 {
337         struct thread_info *thread = task_thread_info(p);
338         struct pt_regs *childregs = task_pt_regs(p);
339
340         *childregs = *regs;
341         childregs->ARM_r0 = 0;
342         childregs->ARM_sp = stack_start;
343
344         memset(&thread->cpu_context, 0, sizeof(struct cpu_context_save));
345         thread->cpu_context.sp = (unsigned long)childregs;
346         thread->cpu_context.pc = (unsigned long)ret_from_fork;
347
348         if (clone_flags & CLONE_SETTLS)
349                 thread->tp_value = regs->ARM_r3;
350
351         return 0;
352 }
353
354 /*
355  * fill in the fpe structure for a core dump...
356  */
357 int dump_fpu (struct pt_regs *regs, struct user_fp *fp)
358 {
359         struct thread_info *thread = current_thread_info();
360         int used_math = thread->used_cp[1] | thread->used_cp[2];
361
362         if (used_math)
363                 memcpy(fp, &thread->fpstate.soft, sizeof (*fp));
364
365         return used_math != 0;
366 }
367 EXPORT_SYMBOL(dump_fpu);
368
369 /*
370  * Shuffle the argument into the correct register before calling the
371  * thread function.  r1 is the thread argument, r2 is the pointer to
372  * the thread function, and r3 points to the exit function.
373  */
374 extern void kernel_thread_helper(void);
375 asm(    ".section .text\n"
376 "       .align\n"
377 "       .type   kernel_thread_helper, #function\n"
378 "kernel_thread_helper:\n"
379 "       mov     r0, r1\n"
380 "       mov     lr, r3\n"
381 "       mov     pc, r2\n"
382 "       .size   kernel_thread_helper, . - kernel_thread_helper\n"
383 "       .previous");
384
385 /*
386  * Create a kernel thread.
387  */
388 pid_t kernel_thread(int (*fn)(void *), void *arg, unsigned long flags)
389 {
390         struct pt_regs regs;
391
392         memset(&regs, 0, sizeof(regs));
393
394         regs.ARM_r1 = (unsigned long)arg;
395         regs.ARM_r2 = (unsigned long)fn;
396         regs.ARM_r3 = (unsigned long)do_exit;
397         regs.ARM_pc = (unsigned long)kernel_thread_helper;
398         regs.ARM_cpsr = SVC_MODE;
399
400         return do_fork(flags|CLONE_VM|CLONE_UNTRACED, 0, &regs, 0, NULL, NULL);
401 }
402 EXPORT_SYMBOL(kernel_thread);
403
404 unsigned long get_wchan(struct task_struct *p)
405 {
406         unsigned long fp, lr;
407         unsigned long stack_start, stack_end;
408         int count = 0;
409         if (!p || p == current || p->state == TASK_RUNNING)
410                 return 0;
411
412         stack_start = (unsigned long)end_of_stack(p);
413         stack_end = (unsigned long)task_stack_page(p) + THREAD_SIZE;
414
415         fp = thread_saved_fp(p);
416         do {
417                 if (fp < stack_start || fp > stack_end)
418                         return 0;
419                 lr = pc_pointer (((unsigned long *)fp)[-1]);
420                 if (!in_sched_functions(lr))
421                         return lr;
422                 fp = *(unsigned long *) (fp - 12);
423         } while (count ++ < 16);
424         return 0;
425 }