Merge commit 'v2.6.29-rc7' into perfcounters/core
[linux-2.6.git] / kernel / profile.c
1 /*
2  *  linux/kernel/profile.c
3  *  Simple profiling. Manages a direct-mapped profile hit count buffer,
4  *  with configurable resolution, support for restricting the cpus on
5  *  which profiling is done, and switching between cpu time and
6  *  schedule() calls via kernel command line parameters passed at boot.
7  *
8  *  Scheduler profiling support, Arjan van de Ven and Ingo Molnar,
9  *      Red Hat, July 2004
10  *  Consolidation of architecture support code for profiling,
11  *      William Irwin, Oracle, July 2004
12  *  Amortized hit count accounting via per-cpu open-addressed hashtables
13  *      to resolve timer interrupt livelocks, William Irwin, Oracle, 2004
14  */
15
16 #include <linux/module.h>
17 #include <linux/profile.h>
18 #include <linux/bootmem.h>
19 #include <linux/notifier.h>
20 #include <linux/mm.h>
21 #include <linux/cpumask.h>
22 #include <linux/cpu.h>
23 #include <linux/highmem.h>
24 #include <linux/mutex.h>
25 #include <linux/slab.h>
26 #include <linux/vmalloc.h>
27 #include <asm/sections.h>
28 #include <asm/irq_regs.h>
29 #include <asm/ptrace.h>
30
31 struct profile_hit {
32         u32 pc, hits;
33 };
34 #define PROFILE_GRPSHIFT        3
35 #define PROFILE_GRPSZ           (1 << PROFILE_GRPSHIFT)
36 #define NR_PROFILE_HIT          (PAGE_SIZE/sizeof(struct profile_hit))
37 #define NR_PROFILE_GRP          (NR_PROFILE_HIT/PROFILE_GRPSZ)
38
39 /* Oprofile timer tick hook */
40 static int (*timer_hook)(struct pt_regs *) __read_mostly;
41
42 static atomic_t *prof_buffer;
43 static unsigned long prof_len, prof_shift;
44
45 int prof_on __read_mostly;
46 EXPORT_SYMBOL_GPL(prof_on);
47
48 static cpumask_var_t prof_cpu_mask;
49 #ifdef CONFIG_SMP
50 static DEFINE_PER_CPU(struct profile_hit *[2], cpu_profile_hits);
51 static DEFINE_PER_CPU(int, cpu_profile_flip);
52 static DEFINE_MUTEX(profile_flip_mutex);
53 #endif /* CONFIG_SMP */
54
55 int profile_setup(char *str)
56 {
57         static char schedstr[] = "schedule";
58         static char sleepstr[] = "sleep";
59         static char kvmstr[] = "kvm";
60         int par;
61
62         if (!strncmp(str, sleepstr, strlen(sleepstr))) {
63 #ifdef CONFIG_SCHEDSTATS
64                 prof_on = SLEEP_PROFILING;
65                 if (str[strlen(sleepstr)] == ',')
66                         str += strlen(sleepstr) + 1;
67                 if (get_option(&str, &par))
68                         prof_shift = par;
69                 printk(KERN_INFO
70                         "kernel sleep profiling enabled (shift: %ld)\n",
71                         prof_shift);
72 #else
73                 printk(KERN_WARNING
74                         "kernel sleep profiling requires CONFIG_SCHEDSTATS\n");
75 #endif /* CONFIG_SCHEDSTATS */
76         } else if (!strncmp(str, schedstr, strlen(schedstr))) {
77                 prof_on = SCHED_PROFILING;
78                 if (str[strlen(schedstr)] == ',')
79                         str += strlen(schedstr) + 1;
80                 if (get_option(&str, &par))
81                         prof_shift = par;
82                 printk(KERN_INFO
83                         "kernel schedule profiling enabled (shift: %ld)\n",
84                         prof_shift);
85         } else if (!strncmp(str, kvmstr, strlen(kvmstr))) {
86                 prof_on = KVM_PROFILING;
87                 if (str[strlen(kvmstr)] == ',')
88                         str += strlen(kvmstr) + 1;
89                 if (get_option(&str, &par))
90                         prof_shift = par;
91                 printk(KERN_INFO
92                         "kernel KVM profiling enabled (shift: %ld)\n",
93                         prof_shift);
94         } else if (get_option(&str, &par)) {
95                 prof_shift = par;
96                 prof_on = CPU_PROFILING;
97                 printk(KERN_INFO "kernel profiling enabled (shift: %ld)\n",
98                         prof_shift);
99         }
100         return 1;
101 }
102 __setup("profile=", profile_setup);
103
104
105 int __ref profile_init(void)
106 {
107         int buffer_bytes;
108         if (!prof_on)
109                 return 0;
110
111         /* only text is profiled */
112         prof_len = (_etext - _stext) >> prof_shift;
113         buffer_bytes = prof_len*sizeof(atomic_t);
114         if (!slab_is_available()) {
115                 prof_buffer = alloc_bootmem(buffer_bytes);
116                 alloc_bootmem_cpumask_var(&prof_cpu_mask);
117                 cpumask_copy(prof_cpu_mask, cpu_possible_mask);
118                 return 0;
119         }
120
121         if (!alloc_cpumask_var(&prof_cpu_mask, GFP_KERNEL))
122                 return -ENOMEM;
123
124         cpumask_copy(prof_cpu_mask, cpu_possible_mask);
125
126         prof_buffer = kzalloc(buffer_bytes, GFP_KERNEL);
127         if (prof_buffer)
128                 return 0;
129
130         prof_buffer = alloc_pages_exact(buffer_bytes, GFP_KERNEL|__GFP_ZERO);
131         if (prof_buffer)
132                 return 0;
133
134         prof_buffer = vmalloc(buffer_bytes);
135         if (prof_buffer)
136                 return 0;
137
138         free_cpumask_var(prof_cpu_mask);
139         return -ENOMEM;
140 }
141
142 /* Profile event notifications */
143
144 static BLOCKING_NOTIFIER_HEAD(task_exit_notifier);
145 static ATOMIC_NOTIFIER_HEAD(task_free_notifier);
146 static BLOCKING_NOTIFIER_HEAD(munmap_notifier);
147
148 void profile_task_exit(struct task_struct *task)
149 {
150         blocking_notifier_call_chain(&task_exit_notifier, 0, task);
151 }
152
153 int profile_handoff_task(struct task_struct *task)
154 {
155         int ret;
156         ret = atomic_notifier_call_chain(&task_free_notifier, 0, task);
157         return (ret == NOTIFY_OK) ? 1 : 0;
158 }
159
160 void profile_munmap(unsigned long addr)
161 {
162         blocking_notifier_call_chain(&munmap_notifier, 0, (void *)addr);
163 }
164
165 int task_handoff_register(struct notifier_block *n)
166 {
167         return atomic_notifier_chain_register(&task_free_notifier, n);
168 }
169 EXPORT_SYMBOL_GPL(task_handoff_register);
170
171 int task_handoff_unregister(struct notifier_block *n)
172 {
173         return atomic_notifier_chain_unregister(&task_free_notifier, n);
174 }
175 EXPORT_SYMBOL_GPL(task_handoff_unregister);
176
177 int profile_event_register(enum profile_type type, struct notifier_block *n)
178 {
179         int err = -EINVAL;
180
181         switch (type) {
182         case PROFILE_TASK_EXIT:
183                 err = blocking_notifier_chain_register(
184                                 &task_exit_notifier, n);
185                 break;
186         case PROFILE_MUNMAP:
187                 err = blocking_notifier_chain_register(
188                                 &munmap_notifier, n);
189                 break;
190         }
191
192         return err;
193 }
194 EXPORT_SYMBOL_GPL(profile_event_register);
195
196 int profile_event_unregister(enum profile_type type, struct notifier_block *n)
197 {
198         int err = -EINVAL;
199
200         switch (type) {
201         case PROFILE_TASK_EXIT:
202                 err = blocking_notifier_chain_unregister(
203                                 &task_exit_notifier, n);
204                 break;
205         case PROFILE_MUNMAP:
206                 err = blocking_notifier_chain_unregister(
207                                 &munmap_notifier, n);
208                 break;
209         }
210
211         return err;
212 }
213 EXPORT_SYMBOL_GPL(profile_event_unregister);
214
215 int register_timer_hook(int (*hook)(struct pt_regs *))
216 {
217         if (timer_hook)
218                 return -EBUSY;
219         timer_hook = hook;
220         return 0;
221 }
222 EXPORT_SYMBOL_GPL(register_timer_hook);
223
224 void unregister_timer_hook(int (*hook)(struct pt_regs *))
225 {
226         WARN_ON(hook != timer_hook);
227         timer_hook = NULL;
228         /* make sure all CPUs see the NULL hook */
229         synchronize_sched();  /* Allow ongoing interrupts to complete. */
230 }
231 EXPORT_SYMBOL_GPL(unregister_timer_hook);
232
233
234 #ifdef CONFIG_SMP
235 /*
236  * Each cpu has a pair of open-addressed hashtables for pending
237  * profile hits. read_profile() IPI's all cpus to request them
238  * to flip buffers and flushes their contents to prof_buffer itself.
239  * Flip requests are serialized by the profile_flip_mutex. The sole
240  * use of having a second hashtable is for avoiding cacheline
241  * contention that would otherwise happen during flushes of pending
242  * profile hits required for the accuracy of reported profile hits
243  * and so resurrect the interrupt livelock issue.
244  *
245  * The open-addressed hashtables are indexed by profile buffer slot
246  * and hold the number of pending hits to that profile buffer slot on
247  * a cpu in an entry. When the hashtable overflows, all pending hits
248  * are accounted to their corresponding profile buffer slots with
249  * atomic_add() and the hashtable emptied. As numerous pending hits
250  * may be accounted to a profile buffer slot in a hashtable entry,
251  * this amortizes a number of atomic profile buffer increments likely
252  * to be far larger than the number of entries in the hashtable,
253  * particularly given that the number of distinct profile buffer
254  * positions to which hits are accounted during short intervals (e.g.
255  * several seconds) is usually very small. Exclusion from buffer
256  * flipping is provided by interrupt disablement (note that for
257  * SCHED_PROFILING or SLEEP_PROFILING profile_hit() may be called from
258  * process context).
259  * The hash function is meant to be lightweight as opposed to strong,
260  * and was vaguely inspired by ppc64 firmware-supported inverted
261  * pagetable hash functions, but uses a full hashtable full of finite
262  * collision chains, not just pairs of them.
263  *
264  * -- wli
265  */
266 static void __profile_flip_buffers(void *unused)
267 {
268         int cpu = smp_processor_id();
269
270         per_cpu(cpu_profile_flip, cpu) = !per_cpu(cpu_profile_flip, cpu);
271 }
272
273 static void profile_flip_buffers(void)
274 {
275         int i, j, cpu;
276
277         mutex_lock(&profile_flip_mutex);
278         j = per_cpu(cpu_profile_flip, get_cpu());
279         put_cpu();
280         on_each_cpu(__profile_flip_buffers, NULL, 1);
281         for_each_online_cpu(cpu) {
282                 struct profile_hit *hits = per_cpu(cpu_profile_hits, cpu)[j];
283                 for (i = 0; i < NR_PROFILE_HIT; ++i) {
284                         if (!hits[i].hits) {
285                                 if (hits[i].pc)
286                                         hits[i].pc = 0;
287                                 continue;
288                         }
289                         atomic_add(hits[i].hits, &prof_buffer[hits[i].pc]);
290                         hits[i].hits = hits[i].pc = 0;
291                 }
292         }
293         mutex_unlock(&profile_flip_mutex);
294 }
295
296 static void profile_discard_flip_buffers(void)
297 {
298         int i, cpu;
299
300         mutex_lock(&profile_flip_mutex);
301         i = per_cpu(cpu_profile_flip, get_cpu());
302         put_cpu();
303         on_each_cpu(__profile_flip_buffers, NULL, 1);
304         for_each_online_cpu(cpu) {
305                 struct profile_hit *hits = per_cpu(cpu_profile_hits, cpu)[i];
306                 memset(hits, 0, NR_PROFILE_HIT*sizeof(struct profile_hit));
307         }
308         mutex_unlock(&profile_flip_mutex);
309 }
310
311 void profile_hits(int type, void *__pc, unsigned int nr_hits)
312 {
313         unsigned long primary, secondary, flags, pc = (unsigned long)__pc;
314         int i, j, cpu;
315         struct profile_hit *hits;
316
317         if (prof_on != type || !prof_buffer)
318                 return;
319         pc = min((pc - (unsigned long)_stext) >> prof_shift, prof_len - 1);
320         i = primary = (pc & (NR_PROFILE_GRP - 1)) << PROFILE_GRPSHIFT;
321         secondary = (~(pc << 1) & (NR_PROFILE_GRP - 1)) << PROFILE_GRPSHIFT;
322         cpu = get_cpu();
323         hits = per_cpu(cpu_profile_hits, cpu)[per_cpu(cpu_profile_flip, cpu)];
324         if (!hits) {
325                 put_cpu();
326                 return;
327         }
328         /*
329          * We buffer the global profiler buffer into a per-CPU
330          * queue and thus reduce the number of global (and possibly
331          * NUMA-alien) accesses. The write-queue is self-coalescing:
332          */
333         local_irq_save(flags);
334         do {
335                 for (j = 0; j < PROFILE_GRPSZ; ++j) {
336                         if (hits[i + j].pc == pc) {
337                                 hits[i + j].hits += nr_hits;
338                                 goto out;
339                         } else if (!hits[i + j].hits) {
340                                 hits[i + j].pc = pc;
341                                 hits[i + j].hits = nr_hits;
342                                 goto out;
343                         }
344                 }
345                 i = (i + secondary) & (NR_PROFILE_HIT - 1);
346         } while (i != primary);
347
348         /*
349          * Add the current hit(s) and flush the write-queue out
350          * to the global buffer:
351          */
352         atomic_add(nr_hits, &prof_buffer[pc]);
353         for (i = 0; i < NR_PROFILE_HIT; ++i) {
354                 atomic_add(hits[i].hits, &prof_buffer[hits[i].pc]);
355                 hits[i].pc = hits[i].hits = 0;
356         }
357 out:
358         local_irq_restore(flags);
359         put_cpu();
360 }
361
362 static int __cpuinit profile_cpu_callback(struct notifier_block *info,
363                                         unsigned long action, void *__cpu)
364 {
365         int node, cpu = (unsigned long)__cpu;
366         struct page *page;
367
368         switch (action) {
369         case CPU_UP_PREPARE:
370         case CPU_UP_PREPARE_FROZEN:
371                 node = cpu_to_node(cpu);
372                 per_cpu(cpu_profile_flip, cpu) = 0;
373                 if (!per_cpu(cpu_profile_hits, cpu)[1]) {
374                         page = alloc_pages_node(node,
375                                         GFP_KERNEL | __GFP_ZERO,
376                                         0);
377                         if (!page)
378                                 return NOTIFY_BAD;
379                         per_cpu(cpu_profile_hits, cpu)[1] = page_address(page);
380                 }
381                 if (!per_cpu(cpu_profile_hits, cpu)[0]) {
382                         page = alloc_pages_node(node,
383                                         GFP_KERNEL | __GFP_ZERO,
384                                         0);
385                         if (!page)
386                                 goto out_free;
387                         per_cpu(cpu_profile_hits, cpu)[0] = page_address(page);
388                 }
389                 break;
390 out_free:
391                 page = virt_to_page(per_cpu(cpu_profile_hits, cpu)[1]);
392                 per_cpu(cpu_profile_hits, cpu)[1] = NULL;
393                 __free_page(page);
394                 return NOTIFY_BAD;
395         case CPU_ONLINE:
396         case CPU_ONLINE_FROZEN:
397                 if (prof_cpu_mask != NULL)
398                         cpumask_set_cpu(cpu, prof_cpu_mask);
399                 break;
400         case CPU_UP_CANCELED:
401         case CPU_UP_CANCELED_FROZEN:
402         case CPU_DEAD:
403         case CPU_DEAD_FROZEN:
404                 if (prof_cpu_mask != NULL)
405                         cpumask_clear_cpu(cpu, prof_cpu_mask);
406                 if (per_cpu(cpu_profile_hits, cpu)[0]) {
407                         page = virt_to_page(per_cpu(cpu_profile_hits, cpu)[0]);
408                         per_cpu(cpu_profile_hits, cpu)[0] = NULL;
409                         __free_page(page);
410                 }
411                 if (per_cpu(cpu_profile_hits, cpu)[1]) {
412                         page = virt_to_page(per_cpu(cpu_profile_hits, cpu)[1]);
413                         per_cpu(cpu_profile_hits, cpu)[1] = NULL;
414                         __free_page(page);
415                 }
416                 break;
417         }
418         return NOTIFY_OK;
419 }
420 #else /* !CONFIG_SMP */
421 #define profile_flip_buffers()          do { } while (0)
422 #define profile_discard_flip_buffers()  do { } while (0)
423 #define profile_cpu_callback            NULL
424
425 void profile_hits(int type, void *__pc, unsigned int nr_hits)
426 {
427         unsigned long pc;
428
429         if (prof_on != type || !prof_buffer)
430                 return;
431         pc = ((unsigned long)__pc - (unsigned long)_stext) >> prof_shift;
432         atomic_add(nr_hits, &prof_buffer[min(pc, prof_len - 1)]);
433 }
434 #endif /* !CONFIG_SMP */
435 EXPORT_SYMBOL_GPL(profile_hits);
436
437 void profile_tick(int type)
438 {
439         struct pt_regs *regs = get_irq_regs();
440
441         if (type == CPU_PROFILING && timer_hook)
442                 timer_hook(regs);
443         if (!user_mode(regs) && prof_cpu_mask != NULL &&
444             cpumask_test_cpu(smp_processor_id(), prof_cpu_mask))
445                 profile_hit(type, (void *)profile_pc(regs));
446 }
447
448 #ifdef CONFIG_PROC_FS
449 #include <linux/proc_fs.h>
450 #include <asm/uaccess.h>
451
452 static int prof_cpu_mask_read_proc(char *page, char **start, off_t off,
453                         int count, int *eof, void *data)
454 {
455         int len = cpumask_scnprintf(page, count, data);
456         if (count - len < 2)
457                 return -EINVAL;
458         len += sprintf(page + len, "\n");
459         return len;
460 }
461
462 static int prof_cpu_mask_write_proc(struct file *file,
463         const char __user *buffer,  unsigned long count, void *data)
464 {
465         struct cpumask *mask = data;
466         unsigned long full_count = count, err;
467         cpumask_var_t new_value;
468
469         if (!alloc_cpumask_var(&new_value, GFP_KERNEL))
470                 return -ENOMEM;
471
472         err = cpumask_parse_user(buffer, count, new_value);
473         if (!err) {
474                 cpumask_copy(mask, new_value);
475                 err = full_count;
476         }
477         free_cpumask_var(new_value);
478         return err;
479 }
480
481 void create_prof_cpu_mask(struct proc_dir_entry *root_irq_dir)
482 {
483         struct proc_dir_entry *entry;
484
485         /* create /proc/irq/prof_cpu_mask */
486         entry = create_proc_entry("prof_cpu_mask", 0600, root_irq_dir);
487         if (!entry)
488                 return;
489         entry->data = prof_cpu_mask;
490         entry->read_proc = prof_cpu_mask_read_proc;
491         entry->write_proc = prof_cpu_mask_write_proc;
492 }
493
494 /*
495  * This function accesses profiling information. The returned data is
496  * binary: the sampling step and the actual contents of the profile
497  * buffer. Use of the program readprofile is recommended in order to
498  * get meaningful info out of these data.
499  */
500 static ssize_t
501 read_profile(struct file *file, char __user *buf, size_t count, loff_t *ppos)
502 {
503         unsigned long p = *ppos;
504         ssize_t read;
505         char *pnt;
506         unsigned int sample_step = 1 << prof_shift;
507
508         profile_flip_buffers();
509         if (p >= (prof_len+1)*sizeof(unsigned int))
510                 return 0;
511         if (count > (prof_len+1)*sizeof(unsigned int) - p)
512                 count = (prof_len+1)*sizeof(unsigned int) - p;
513         read = 0;
514
515         while (p < sizeof(unsigned int) && count > 0) {
516                 if (put_user(*((char *)(&sample_step)+p), buf))
517                         return -EFAULT;
518                 buf++; p++; count--; read++;
519         }
520         pnt = (char *)prof_buffer + p - sizeof(atomic_t);
521         if (copy_to_user(buf, (void *)pnt, count))
522                 return -EFAULT;
523         read += count;
524         *ppos += read;
525         return read;
526 }
527
528 /*
529  * Writing to /proc/profile resets the counters
530  *
531  * Writing a 'profiling multiplier' value into it also re-sets the profiling
532  * interrupt frequency, on architectures that support this.
533  */
534 static ssize_t write_profile(struct file *file, const char __user *buf,
535                              size_t count, loff_t *ppos)
536 {
537 #ifdef CONFIG_SMP
538         extern int setup_profiling_timer(unsigned int multiplier);
539
540         if (count == sizeof(int)) {
541                 unsigned int multiplier;
542
543                 if (copy_from_user(&multiplier, buf, sizeof(int)))
544                         return -EFAULT;
545
546                 if (setup_profiling_timer(multiplier))
547                         return -EINVAL;
548         }
549 #endif
550         profile_discard_flip_buffers();
551         memset(prof_buffer, 0, prof_len * sizeof(atomic_t));
552         return count;
553 }
554
555 static const struct file_operations proc_profile_operations = {
556         .read           = read_profile,
557         .write          = write_profile,
558 };
559
560 #ifdef CONFIG_SMP
561 static void profile_nop(void *unused)
562 {
563 }
564
565 static int create_hash_tables(void)
566 {
567         int cpu;
568
569         for_each_online_cpu(cpu) {
570                 int node = cpu_to_node(cpu);
571                 struct page *page;
572
573                 page = alloc_pages_node(node,
574                                 GFP_KERNEL | __GFP_ZERO | GFP_THISNODE,
575                                 0);
576                 if (!page)
577                         goto out_cleanup;
578                 per_cpu(cpu_profile_hits, cpu)[1]
579                                 = (struct profile_hit *)page_address(page);
580                 page = alloc_pages_node(node,
581                                 GFP_KERNEL | __GFP_ZERO | GFP_THISNODE,
582                                 0);
583                 if (!page)
584                         goto out_cleanup;
585                 per_cpu(cpu_profile_hits, cpu)[0]
586                                 = (struct profile_hit *)page_address(page);
587         }
588         return 0;
589 out_cleanup:
590         prof_on = 0;
591         smp_mb();
592         on_each_cpu(profile_nop, NULL, 1);
593         for_each_online_cpu(cpu) {
594                 struct page *page;
595
596                 if (per_cpu(cpu_profile_hits, cpu)[0]) {
597                         page = virt_to_page(per_cpu(cpu_profile_hits, cpu)[0]);
598                         per_cpu(cpu_profile_hits, cpu)[0] = NULL;
599                         __free_page(page);
600                 }
601                 if (per_cpu(cpu_profile_hits, cpu)[1]) {
602                         page = virt_to_page(per_cpu(cpu_profile_hits, cpu)[1]);
603                         per_cpu(cpu_profile_hits, cpu)[1] = NULL;
604                         __free_page(page);
605                 }
606         }
607         return -1;
608 }
609 #else
610 #define create_hash_tables()                    ({ 0; })
611 #endif
612
613 int __ref create_proc_profile(void) /* false positive from hotcpu_notifier */
614 {
615         struct proc_dir_entry *entry;
616
617         if (!prof_on)
618                 return 0;
619         if (create_hash_tables())
620                 return -ENOMEM;
621         entry = proc_create("profile", S_IWUSR | S_IRUGO,
622                             NULL, &proc_profile_operations);
623         if (!entry)
624                 return 0;
625         entry->size = (1+prof_len) * sizeof(atomic_t);
626         hotcpu_notifier(profile_cpu_callback, 0);
627         return 0;
628 }
629 module_init(create_proc_profile);
630 #endif /* CONFIG_PROC_FS */