kernel/profile: fix profile_init() section mismatch
[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_t prof_cpu_mask = CPU_MASK_ALL;
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                 return 0;
117         }
118
119         prof_buffer = kzalloc(buffer_bytes, GFP_KERNEL);
120         if (prof_buffer)
121                 return 0;
122
123         prof_buffer = alloc_pages_exact(buffer_bytes, GFP_KERNEL|__GFP_ZERO);
124         if (prof_buffer)
125                 return 0;
126
127         prof_buffer = vmalloc(buffer_bytes);
128         if (prof_buffer)
129                 return 0;
130
131         return -ENOMEM;
132 }
133
134 /* Profile event notifications */
135
136 static BLOCKING_NOTIFIER_HEAD(task_exit_notifier);
137 static ATOMIC_NOTIFIER_HEAD(task_free_notifier);
138 static BLOCKING_NOTIFIER_HEAD(munmap_notifier);
139
140 void profile_task_exit(struct task_struct *task)
141 {
142         blocking_notifier_call_chain(&task_exit_notifier, 0, task);
143 }
144
145 int profile_handoff_task(struct task_struct *task)
146 {
147         int ret;
148         ret = atomic_notifier_call_chain(&task_free_notifier, 0, task);
149         return (ret == NOTIFY_OK) ? 1 : 0;
150 }
151
152 void profile_munmap(unsigned long addr)
153 {
154         blocking_notifier_call_chain(&munmap_notifier, 0, (void *)addr);
155 }
156
157 int task_handoff_register(struct notifier_block *n)
158 {
159         return atomic_notifier_chain_register(&task_free_notifier, n);
160 }
161 EXPORT_SYMBOL_GPL(task_handoff_register);
162
163 int task_handoff_unregister(struct notifier_block *n)
164 {
165         return atomic_notifier_chain_unregister(&task_free_notifier, n);
166 }
167 EXPORT_SYMBOL_GPL(task_handoff_unregister);
168
169 int profile_event_register(enum profile_type type, struct notifier_block *n)
170 {
171         int err = -EINVAL;
172
173         switch (type) {
174         case PROFILE_TASK_EXIT:
175                 err = blocking_notifier_chain_register(
176                                 &task_exit_notifier, n);
177                 break;
178         case PROFILE_MUNMAP:
179                 err = blocking_notifier_chain_register(
180                                 &munmap_notifier, n);
181                 break;
182         }
183
184         return err;
185 }
186 EXPORT_SYMBOL_GPL(profile_event_register);
187
188 int profile_event_unregister(enum profile_type type, struct notifier_block *n)
189 {
190         int err = -EINVAL;
191
192         switch (type) {
193         case PROFILE_TASK_EXIT:
194                 err = blocking_notifier_chain_unregister(
195                                 &task_exit_notifier, n);
196                 break;
197         case PROFILE_MUNMAP:
198                 err = blocking_notifier_chain_unregister(
199                                 &munmap_notifier, n);
200                 break;
201         }
202
203         return err;
204 }
205 EXPORT_SYMBOL_GPL(profile_event_unregister);
206
207 int register_timer_hook(int (*hook)(struct pt_regs *))
208 {
209         if (timer_hook)
210                 return -EBUSY;
211         timer_hook = hook;
212         return 0;
213 }
214 EXPORT_SYMBOL_GPL(register_timer_hook);
215
216 void unregister_timer_hook(int (*hook)(struct pt_regs *))
217 {
218         WARN_ON(hook != timer_hook);
219         timer_hook = NULL;
220         /* make sure all CPUs see the NULL hook */
221         synchronize_sched();  /* Allow ongoing interrupts to complete. */
222 }
223 EXPORT_SYMBOL_GPL(unregister_timer_hook);
224
225
226 #ifdef CONFIG_SMP
227 /*
228  * Each cpu has a pair of open-addressed hashtables for pending
229  * profile hits. read_profile() IPI's all cpus to request them
230  * to flip buffers and flushes their contents to prof_buffer itself.
231  * Flip requests are serialized by the profile_flip_mutex. The sole
232  * use of having a second hashtable is for avoiding cacheline
233  * contention that would otherwise happen during flushes of pending
234  * profile hits required for the accuracy of reported profile hits
235  * and so resurrect the interrupt livelock issue.
236  *
237  * The open-addressed hashtables are indexed by profile buffer slot
238  * and hold the number of pending hits to that profile buffer slot on
239  * a cpu in an entry. When the hashtable overflows, all pending hits
240  * are accounted to their corresponding profile buffer slots with
241  * atomic_add() and the hashtable emptied. As numerous pending hits
242  * may be accounted to a profile buffer slot in a hashtable entry,
243  * this amortizes a number of atomic profile buffer increments likely
244  * to be far larger than the number of entries in the hashtable,
245  * particularly given that the number of distinct profile buffer
246  * positions to which hits are accounted during short intervals (e.g.
247  * several seconds) is usually very small. Exclusion from buffer
248  * flipping is provided by interrupt disablement (note that for
249  * SCHED_PROFILING or SLEEP_PROFILING profile_hit() may be called from
250  * process context).
251  * The hash function is meant to be lightweight as opposed to strong,
252  * and was vaguely inspired by ppc64 firmware-supported inverted
253  * pagetable hash functions, but uses a full hashtable full of finite
254  * collision chains, not just pairs of them.
255  *
256  * -- wli
257  */
258 static void __profile_flip_buffers(void *unused)
259 {
260         int cpu = smp_processor_id();
261
262         per_cpu(cpu_profile_flip, cpu) = !per_cpu(cpu_profile_flip, cpu);
263 }
264
265 static void profile_flip_buffers(void)
266 {
267         int i, j, cpu;
268
269         mutex_lock(&profile_flip_mutex);
270         j = per_cpu(cpu_profile_flip, get_cpu());
271         put_cpu();
272         on_each_cpu(__profile_flip_buffers, NULL, 1);
273         for_each_online_cpu(cpu) {
274                 struct profile_hit *hits = per_cpu(cpu_profile_hits, cpu)[j];
275                 for (i = 0; i < NR_PROFILE_HIT; ++i) {
276                         if (!hits[i].hits) {
277                                 if (hits[i].pc)
278                                         hits[i].pc = 0;
279                                 continue;
280                         }
281                         atomic_add(hits[i].hits, &prof_buffer[hits[i].pc]);
282                         hits[i].hits = hits[i].pc = 0;
283                 }
284         }
285         mutex_unlock(&profile_flip_mutex);
286 }
287
288 static void profile_discard_flip_buffers(void)
289 {
290         int i, cpu;
291
292         mutex_lock(&profile_flip_mutex);
293         i = per_cpu(cpu_profile_flip, get_cpu());
294         put_cpu();
295         on_each_cpu(__profile_flip_buffers, NULL, 1);
296         for_each_online_cpu(cpu) {
297                 struct profile_hit *hits = per_cpu(cpu_profile_hits, cpu)[i];
298                 memset(hits, 0, NR_PROFILE_HIT*sizeof(struct profile_hit));
299         }
300         mutex_unlock(&profile_flip_mutex);
301 }
302
303 void profile_hits(int type, void *__pc, unsigned int nr_hits)
304 {
305         unsigned long primary, secondary, flags, pc = (unsigned long)__pc;
306         int i, j, cpu;
307         struct profile_hit *hits;
308
309         if (prof_on != type || !prof_buffer)
310                 return;
311         pc = min((pc - (unsigned long)_stext) >> prof_shift, prof_len - 1);
312         i = primary = (pc & (NR_PROFILE_GRP - 1)) << PROFILE_GRPSHIFT;
313         secondary = (~(pc << 1) & (NR_PROFILE_GRP - 1)) << PROFILE_GRPSHIFT;
314         cpu = get_cpu();
315         hits = per_cpu(cpu_profile_hits, cpu)[per_cpu(cpu_profile_flip, cpu)];
316         if (!hits) {
317                 put_cpu();
318                 return;
319         }
320         /*
321          * We buffer the global profiler buffer into a per-CPU
322          * queue and thus reduce the number of global (and possibly
323          * NUMA-alien) accesses. The write-queue is self-coalescing:
324          */
325         local_irq_save(flags);
326         do {
327                 for (j = 0; j < PROFILE_GRPSZ; ++j) {
328                         if (hits[i + j].pc == pc) {
329                                 hits[i + j].hits += nr_hits;
330                                 goto out;
331                         } else if (!hits[i + j].hits) {
332                                 hits[i + j].pc = pc;
333                                 hits[i + j].hits = nr_hits;
334                                 goto out;
335                         }
336                 }
337                 i = (i + secondary) & (NR_PROFILE_HIT - 1);
338         } while (i != primary);
339
340         /*
341          * Add the current hit(s) and flush the write-queue out
342          * to the global buffer:
343          */
344         atomic_add(nr_hits, &prof_buffer[pc]);
345         for (i = 0; i < NR_PROFILE_HIT; ++i) {
346                 atomic_add(hits[i].hits, &prof_buffer[hits[i].pc]);
347                 hits[i].pc = hits[i].hits = 0;
348         }
349 out:
350         local_irq_restore(flags);
351         put_cpu();
352 }
353
354 static int __devinit profile_cpu_callback(struct notifier_block *info,
355                                         unsigned long action, void *__cpu)
356 {
357         int node, cpu = (unsigned long)__cpu;
358         struct page *page;
359
360         switch (action) {
361         case CPU_UP_PREPARE:
362         case CPU_UP_PREPARE_FROZEN:
363                 node = cpu_to_node(cpu);
364                 per_cpu(cpu_profile_flip, cpu) = 0;
365                 if (!per_cpu(cpu_profile_hits, cpu)[1]) {
366                         page = alloc_pages_node(node,
367                                         GFP_KERNEL | __GFP_ZERO,
368                                         0);
369                         if (!page)
370                                 return NOTIFY_BAD;
371                         per_cpu(cpu_profile_hits, cpu)[1] = page_address(page);
372                 }
373                 if (!per_cpu(cpu_profile_hits, cpu)[0]) {
374                         page = alloc_pages_node(node,
375                                         GFP_KERNEL | __GFP_ZERO,
376                                         0);
377                         if (!page)
378                                 goto out_free;
379                         per_cpu(cpu_profile_hits, cpu)[0] = page_address(page);
380                 }
381                 break;
382 out_free:
383                 page = virt_to_page(per_cpu(cpu_profile_hits, cpu)[1]);
384                 per_cpu(cpu_profile_hits, cpu)[1] = NULL;
385                 __free_page(page);
386                 return NOTIFY_BAD;
387         case CPU_ONLINE:
388         case CPU_ONLINE_FROZEN:
389                 cpu_set(cpu, prof_cpu_mask);
390                 break;
391         case CPU_UP_CANCELED:
392         case CPU_UP_CANCELED_FROZEN:
393         case CPU_DEAD:
394         case CPU_DEAD_FROZEN:
395                 cpu_clear(cpu, prof_cpu_mask);
396                 if (per_cpu(cpu_profile_hits, cpu)[0]) {
397                         page = virt_to_page(per_cpu(cpu_profile_hits, cpu)[0]);
398                         per_cpu(cpu_profile_hits, cpu)[0] = NULL;
399                         __free_page(page);
400                 }
401                 if (per_cpu(cpu_profile_hits, cpu)[1]) {
402                         page = virt_to_page(per_cpu(cpu_profile_hits, cpu)[1]);
403                         per_cpu(cpu_profile_hits, cpu)[1] = NULL;
404                         __free_page(page);
405                 }
406                 break;
407         }
408         return NOTIFY_OK;
409 }
410 #else /* !CONFIG_SMP */
411 #define profile_flip_buffers()          do { } while (0)
412 #define profile_discard_flip_buffers()  do { } while (0)
413 #define profile_cpu_callback            NULL
414
415 void profile_hits(int type, void *__pc, unsigned int nr_hits)
416 {
417         unsigned long pc;
418
419         if (prof_on != type || !prof_buffer)
420                 return;
421         pc = ((unsigned long)__pc - (unsigned long)_stext) >> prof_shift;
422         atomic_add(nr_hits, &prof_buffer[min(pc, prof_len - 1)]);
423 }
424 #endif /* !CONFIG_SMP */
425 EXPORT_SYMBOL_GPL(profile_hits);
426
427 void profile_tick(int type)
428 {
429         struct pt_regs *regs = get_irq_regs();
430
431         if (type == CPU_PROFILING && timer_hook)
432                 timer_hook(regs);
433         if (!user_mode(regs) && cpu_isset(smp_processor_id(), prof_cpu_mask))
434                 profile_hit(type, (void *)profile_pc(regs));
435 }
436
437 #ifdef CONFIG_PROC_FS
438 #include <linux/proc_fs.h>
439 #include <asm/uaccess.h>
440 #include <asm/ptrace.h>
441
442 static int prof_cpu_mask_read_proc(char *page, char **start, off_t off,
443                         int count, int *eof, void *data)
444 {
445         int len = cpumask_scnprintf(page, count, *(cpumask_t *)data);
446         if (count - len < 2)
447                 return -EINVAL;
448         len += sprintf(page + len, "\n");
449         return len;
450 }
451
452 static int prof_cpu_mask_write_proc(struct file *file,
453         const char __user *buffer,  unsigned long count, void *data)
454 {
455         cpumask_t *mask = (cpumask_t *)data;
456         unsigned long full_count = count, err;
457         cpumask_t new_value;
458
459         err = cpumask_parse_user(buffer, count, new_value);
460         if (err)
461                 return err;
462
463         *mask = new_value;
464         return full_count;
465 }
466
467 void create_prof_cpu_mask(struct proc_dir_entry *root_irq_dir)
468 {
469         struct proc_dir_entry *entry;
470
471         /* create /proc/irq/prof_cpu_mask */
472         entry = create_proc_entry("prof_cpu_mask", 0600, root_irq_dir);
473         if (!entry)
474                 return;
475         entry->data = (void *)&prof_cpu_mask;
476         entry->read_proc = prof_cpu_mask_read_proc;
477         entry->write_proc = prof_cpu_mask_write_proc;
478 }
479
480 /*
481  * This function accesses profiling information. The returned data is
482  * binary: the sampling step and the actual contents of the profile
483  * buffer. Use of the program readprofile is recommended in order to
484  * get meaningful info out of these data.
485  */
486 static ssize_t
487 read_profile(struct file *file, char __user *buf, size_t count, loff_t *ppos)
488 {
489         unsigned long p = *ppos;
490         ssize_t read;
491         char *pnt;
492         unsigned int sample_step = 1 << prof_shift;
493
494         profile_flip_buffers();
495         if (p >= (prof_len+1)*sizeof(unsigned int))
496                 return 0;
497         if (count > (prof_len+1)*sizeof(unsigned int) - p)
498                 count = (prof_len+1)*sizeof(unsigned int) - p;
499         read = 0;
500
501         while (p < sizeof(unsigned int) && count > 0) {
502                 if (put_user(*((char *)(&sample_step)+p), buf))
503                         return -EFAULT;
504                 buf++; p++; count--; read++;
505         }
506         pnt = (char *)prof_buffer + p - sizeof(atomic_t);
507         if (copy_to_user(buf, (void *)pnt, count))
508                 return -EFAULT;
509         read += count;
510         *ppos += read;
511         return read;
512 }
513
514 /*
515  * Writing to /proc/profile resets the counters
516  *
517  * Writing a 'profiling multiplier' value into it also re-sets the profiling
518  * interrupt frequency, on architectures that support this.
519  */
520 static ssize_t write_profile(struct file *file, const char __user *buf,
521                              size_t count, loff_t *ppos)
522 {
523 #ifdef CONFIG_SMP
524         extern int setup_profiling_timer(unsigned int multiplier);
525
526         if (count == sizeof(int)) {
527                 unsigned int multiplier;
528
529                 if (copy_from_user(&multiplier, buf, sizeof(int)))
530                         return -EFAULT;
531
532                 if (setup_profiling_timer(multiplier))
533                         return -EINVAL;
534         }
535 #endif
536         profile_discard_flip_buffers();
537         memset(prof_buffer, 0, prof_len * sizeof(atomic_t));
538         return count;
539 }
540
541 static const struct file_operations proc_profile_operations = {
542         .read           = read_profile,
543         .write          = write_profile,
544 };
545
546 #ifdef CONFIG_SMP
547 static void __init profile_nop(void *unused)
548 {
549 }
550
551 static int create_hash_tables(void)
552 {
553         int cpu;
554
555         for_each_online_cpu(cpu) {
556                 int node = cpu_to_node(cpu);
557                 struct page *page;
558
559                 page = alloc_pages_node(node,
560                                 GFP_KERNEL | __GFP_ZERO | GFP_THISNODE,
561                                 0);
562                 if (!page)
563                         goto out_cleanup;
564                 per_cpu(cpu_profile_hits, cpu)[1]
565                                 = (struct profile_hit *)page_address(page);
566                 page = alloc_pages_node(node,
567                                 GFP_KERNEL | __GFP_ZERO | GFP_THISNODE,
568                                 0);
569                 if (!page)
570                         goto out_cleanup;
571                 per_cpu(cpu_profile_hits, cpu)[0]
572                                 = (struct profile_hit *)page_address(page);
573         }
574         return 0;
575 out_cleanup:
576         prof_on = 0;
577         smp_mb();
578         on_each_cpu(profile_nop, NULL, 1);
579         for_each_online_cpu(cpu) {
580                 struct page *page;
581
582                 if (per_cpu(cpu_profile_hits, cpu)[0]) {
583                         page = virt_to_page(per_cpu(cpu_profile_hits, cpu)[0]);
584                         per_cpu(cpu_profile_hits, cpu)[0] = NULL;
585                         __free_page(page);
586                 }
587                 if (per_cpu(cpu_profile_hits, cpu)[1]) {
588                         page = virt_to_page(per_cpu(cpu_profile_hits, cpu)[1]);
589                         per_cpu(cpu_profile_hits, cpu)[1] = NULL;
590                         __free_page(page);
591                 }
592         }
593         return -1;
594 }
595 #else
596 #define create_hash_tables()                    ({ 0; })
597 #endif
598
599 int create_proc_profile(void)
600 {
601         struct proc_dir_entry *entry;
602
603         if (!prof_on)
604                 return 0;
605         if (create_hash_tables())
606                 return -ENOMEM;
607         entry = proc_create("profile", S_IWUSR | S_IRUGO,
608                             NULL, &proc_profile_operations);
609         if (!entry)
610                 return 0;
611         entry->size = (1+prof_len) * sizeof(atomic_t);
612         hotcpu_notifier(profile_cpu_callback, 0);
613         return 0;
614 }
615 module_init(create_proc_profile);
616 #endif /* CONFIG_PROC_FS */