media: tegra: Tegra videobuf2
[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
115         if (!alloc_cpumask_var(&prof_cpu_mask, GFP_KERNEL))
116                 return -ENOMEM;
117
118         cpumask_copy(prof_cpu_mask, cpu_possible_mask);
119
120         prof_buffer = kzalloc(buffer_bytes, GFP_KERNEL|__GFP_NOWARN);
121         if (prof_buffer)
122                 return 0;
123
124         prof_buffer = alloc_pages_exact(buffer_bytes,
125                                         GFP_KERNEL|__GFP_ZERO|__GFP_NOWARN);
126         if (prof_buffer)
127                 return 0;
128
129         prof_buffer = vzalloc(buffer_bytes);
130         if (prof_buffer)
131                 return 0;
132
133         free_cpumask_var(prof_cpu_mask);
134         return -ENOMEM;
135 }
136
137 /* Profile event notifications */
138
139 static BLOCKING_NOTIFIER_HEAD(task_exit_notifier);
140 static ATOMIC_NOTIFIER_HEAD(task_free_notifier);
141 static BLOCKING_NOTIFIER_HEAD(munmap_notifier);
142
143 void profile_task_exit(struct task_struct *task)
144 {
145         blocking_notifier_call_chain(&task_exit_notifier, 0, task);
146 }
147
148 int profile_handoff_task(struct task_struct *task)
149 {
150         int ret;
151         ret = atomic_notifier_call_chain(&task_free_notifier, 0, task);
152         return (ret == NOTIFY_OK) ? 1 : 0;
153 }
154
155 void profile_munmap(unsigned long addr)
156 {
157         blocking_notifier_call_chain(&munmap_notifier, 0, (void *)addr);
158 }
159
160 int task_handoff_register(struct notifier_block *n)
161 {
162         return atomic_notifier_chain_register(&task_free_notifier, n);
163 }
164 EXPORT_SYMBOL_GPL(task_handoff_register);
165
166 int task_handoff_unregister(struct notifier_block *n)
167 {
168         return atomic_notifier_chain_unregister(&task_free_notifier, n);
169 }
170 EXPORT_SYMBOL_GPL(task_handoff_unregister);
171
172 int profile_event_register(enum profile_type type, struct notifier_block *n)
173 {
174         int err = -EINVAL;
175
176         switch (type) {
177         case PROFILE_TASK_EXIT:
178                 err = blocking_notifier_chain_register(
179                                 &task_exit_notifier, n);
180                 break;
181         case PROFILE_MUNMAP:
182                 err = blocking_notifier_chain_register(
183                                 &munmap_notifier, n);
184                 break;
185         }
186
187         return err;
188 }
189 EXPORT_SYMBOL_GPL(profile_event_register);
190
191 int profile_event_unregister(enum profile_type type, struct notifier_block *n)
192 {
193         int err = -EINVAL;
194
195         switch (type) {
196         case PROFILE_TASK_EXIT:
197                 err = blocking_notifier_chain_unregister(
198                                 &task_exit_notifier, n);
199                 break;
200         case PROFILE_MUNMAP:
201                 err = blocking_notifier_chain_unregister(
202                                 &munmap_notifier, n);
203                 break;
204         }
205
206         return err;
207 }
208 EXPORT_SYMBOL_GPL(profile_event_unregister);
209
210 int register_timer_hook(int (*hook)(struct pt_regs *))
211 {
212         if (timer_hook)
213                 return -EBUSY;
214         timer_hook = hook;
215         return 0;
216 }
217 EXPORT_SYMBOL_GPL(register_timer_hook);
218
219 void unregister_timer_hook(int (*hook)(struct pt_regs *))
220 {
221         WARN_ON(hook != timer_hook);
222         timer_hook = NULL;
223         /* make sure all CPUs see the NULL hook */
224         synchronize_sched();  /* Allow ongoing interrupts to complete. */
225 }
226 EXPORT_SYMBOL_GPL(unregister_timer_hook);
227
228
229 #ifdef CONFIG_SMP
230 /*
231  * Each cpu has a pair of open-addressed hashtables for pending
232  * profile hits. read_profile() IPI's all cpus to request them
233  * to flip buffers and flushes their contents to prof_buffer itself.
234  * Flip requests are serialized by the profile_flip_mutex. The sole
235  * use of having a second hashtable is for avoiding cacheline
236  * contention that would otherwise happen during flushes of pending
237  * profile hits required for the accuracy of reported profile hits
238  * and so resurrect the interrupt livelock issue.
239  *
240  * The open-addressed hashtables are indexed by profile buffer slot
241  * and hold the number of pending hits to that profile buffer slot on
242  * a cpu in an entry. When the hashtable overflows, all pending hits
243  * are accounted to their corresponding profile buffer slots with
244  * atomic_add() and the hashtable emptied. As numerous pending hits
245  * may be accounted to a profile buffer slot in a hashtable entry,
246  * this amortizes a number of atomic profile buffer increments likely
247  * to be far larger than the number of entries in the hashtable,
248  * particularly given that the number of distinct profile buffer
249  * positions to which hits are accounted during short intervals (e.g.
250  * several seconds) is usually very small. Exclusion from buffer
251  * flipping is provided by interrupt disablement (note that for
252  * SCHED_PROFILING or SLEEP_PROFILING profile_hit() may be called from
253  * process context).
254  * The hash function is meant to be lightweight as opposed to strong,
255  * and was vaguely inspired by ppc64 firmware-supported inverted
256  * pagetable hash functions, but uses a full hashtable full of finite
257  * collision chains, not just pairs of them.
258  *
259  * -- wli
260  */
261 static void __profile_flip_buffers(void *unused)
262 {
263         int cpu = smp_processor_id();
264
265         per_cpu(cpu_profile_flip, cpu) = !per_cpu(cpu_profile_flip, cpu);
266 }
267
268 static void profile_flip_buffers(void)
269 {
270         int i, j, cpu;
271
272         mutex_lock(&profile_flip_mutex);
273         j = per_cpu(cpu_profile_flip, get_cpu());
274         put_cpu();
275         on_each_cpu(__profile_flip_buffers, NULL, 1);
276         for_each_online_cpu(cpu) {
277                 struct profile_hit *hits = per_cpu(cpu_profile_hits, cpu)[j];
278                 for (i = 0; i < NR_PROFILE_HIT; ++i) {
279                         if (!hits[i].hits) {
280                                 if (hits[i].pc)
281                                         hits[i].pc = 0;
282                                 continue;
283                         }
284                         atomic_add(hits[i].hits, &prof_buffer[hits[i].pc]);
285                         hits[i].hits = hits[i].pc = 0;
286                 }
287         }
288         mutex_unlock(&profile_flip_mutex);
289 }
290
291 static void profile_discard_flip_buffers(void)
292 {
293         int i, cpu;
294
295         mutex_lock(&profile_flip_mutex);
296         i = per_cpu(cpu_profile_flip, get_cpu());
297         put_cpu();
298         on_each_cpu(__profile_flip_buffers, NULL, 1);
299         for_each_online_cpu(cpu) {
300                 struct profile_hit *hits = per_cpu(cpu_profile_hits, cpu)[i];
301                 memset(hits, 0, NR_PROFILE_HIT*sizeof(struct profile_hit));
302         }
303         mutex_unlock(&profile_flip_mutex);
304 }
305
306 static void do_profile_hits(int type, void *__pc, unsigned int nr_hits)
307 {
308         unsigned long primary, secondary, flags, pc = (unsigned long)__pc;
309         int i, j, cpu;
310         struct profile_hit *hits;
311
312         pc = min((pc - (unsigned long)_stext) >> prof_shift, prof_len - 1);
313         i = primary = (pc & (NR_PROFILE_GRP - 1)) << PROFILE_GRPSHIFT;
314         secondary = (~(pc << 1) & (NR_PROFILE_GRP - 1)) << PROFILE_GRPSHIFT;
315         cpu = get_cpu();
316         hits = per_cpu(cpu_profile_hits, cpu)[per_cpu(cpu_profile_flip, cpu)];
317         if (!hits) {
318                 put_cpu();
319                 return;
320         }
321         /*
322          * We buffer the global profiler buffer into a per-CPU
323          * queue and thus reduce the number of global (and possibly
324          * NUMA-alien) accesses. The write-queue is self-coalescing:
325          */
326         local_irq_save(flags);
327         do {
328                 for (j = 0; j < PROFILE_GRPSZ; ++j) {
329                         if (hits[i + j].pc == pc) {
330                                 hits[i + j].hits += nr_hits;
331                                 goto out;
332                         } else if (!hits[i + j].hits) {
333                                 hits[i + j].pc = pc;
334                                 hits[i + j].hits = nr_hits;
335                                 goto out;
336                         }
337                 }
338                 i = (i + secondary) & (NR_PROFILE_HIT - 1);
339         } while (i != primary);
340
341         /*
342          * Add the current hit(s) and flush the write-queue out
343          * to the global buffer:
344          */
345         atomic_add(nr_hits, &prof_buffer[pc]);
346         for (i = 0; i < NR_PROFILE_HIT; ++i) {
347                 atomic_add(hits[i].hits, &prof_buffer[hits[i].pc]);
348                 hits[i].pc = hits[i].hits = 0;
349         }
350 out:
351         local_irq_restore(flags);
352         put_cpu();
353 }
354
355 static int __cpuinit profile_cpu_callback(struct notifier_block *info,
356                                         unsigned long action, void *__cpu)
357 {
358         int node, cpu = (unsigned long)__cpu;
359         struct page *page;
360
361         switch (action) {
362         case CPU_UP_PREPARE:
363         case CPU_UP_PREPARE_FROZEN:
364                 node = cpu_to_mem(cpu);
365                 per_cpu(cpu_profile_flip, cpu) = 0;
366                 if (!per_cpu(cpu_profile_hits, cpu)[1]) {
367                         page = alloc_pages_exact_node(node,
368                                         GFP_KERNEL | __GFP_ZERO,
369                                         0);
370                         if (!page)
371                                 return notifier_from_errno(-ENOMEM);
372                         per_cpu(cpu_profile_hits, cpu)[1] = page_address(page);
373                 }
374                 if (!per_cpu(cpu_profile_hits, cpu)[0]) {
375                         page = alloc_pages_exact_node(node,
376                                         GFP_KERNEL | __GFP_ZERO,
377                                         0);
378                         if (!page)
379                                 goto out_free;
380                         per_cpu(cpu_profile_hits, cpu)[0] = page_address(page);
381                 }
382                 break;
383 out_free:
384                 page = virt_to_page(per_cpu(cpu_profile_hits, cpu)[1]);
385                 per_cpu(cpu_profile_hits, cpu)[1] = NULL;
386                 __free_page(page);
387                 return notifier_from_errno(-ENOMEM);
388         case CPU_ONLINE:
389         case CPU_ONLINE_FROZEN:
390                 if (prof_cpu_mask != NULL)
391                         cpumask_set_cpu(cpu, prof_cpu_mask);
392                 break;
393         case CPU_UP_CANCELED:
394         case CPU_UP_CANCELED_FROZEN:
395         case CPU_DEAD:
396         case CPU_DEAD_FROZEN:
397                 if (prof_cpu_mask != NULL)
398                         cpumask_clear_cpu(cpu, prof_cpu_mask);
399                 if (per_cpu(cpu_profile_hits, cpu)[0]) {
400                         page = virt_to_page(per_cpu(cpu_profile_hits, cpu)[0]);
401                         per_cpu(cpu_profile_hits, cpu)[0] = NULL;
402                         __free_page(page);
403                 }
404                 if (per_cpu(cpu_profile_hits, cpu)[1]) {
405                         page = virt_to_page(per_cpu(cpu_profile_hits, cpu)[1]);
406                         per_cpu(cpu_profile_hits, cpu)[1] = NULL;
407                         __free_page(page);
408                 }
409                 break;
410         }
411         return NOTIFY_OK;
412 }
413 #else /* !CONFIG_SMP */
414 #define profile_flip_buffers()          do { } while (0)
415 #define profile_discard_flip_buffers()  do { } while (0)
416 #define profile_cpu_callback            NULL
417
418 static void do_profile_hits(int type, void *__pc, unsigned int nr_hits)
419 {
420         unsigned long pc;
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
426 void profile_hits(int type, void *__pc, unsigned int nr_hits)
427 {
428         if (prof_on != type || !prof_buffer)
429                 return;
430         do_profile_hits(type, __pc, nr_hits);
431 }
432 EXPORT_SYMBOL_GPL(profile_hits);
433
434 void profile_tick(int type)
435 {
436         struct pt_regs *regs = get_irq_regs();
437
438         if (type == CPU_PROFILING && timer_hook)
439                 timer_hook(regs);
440         if (!user_mode(regs) && prof_cpu_mask != NULL &&
441             cpumask_test_cpu(smp_processor_id(), prof_cpu_mask))
442                 profile_hit(type, (void *)profile_pc(regs));
443 }
444
445 #ifdef CONFIG_PROC_FS
446 #include <linux/proc_fs.h>
447 #include <linux/seq_file.h>
448 #include <asm/uaccess.h>
449
450 static int prof_cpu_mask_proc_show(struct seq_file *m, void *v)
451 {
452         seq_cpumask(m, prof_cpu_mask);
453         seq_putc(m, '\n');
454         return 0;
455 }
456
457 static int prof_cpu_mask_proc_open(struct inode *inode, struct file *file)
458 {
459         return single_open(file, prof_cpu_mask_proc_show, NULL);
460 }
461
462 static ssize_t prof_cpu_mask_proc_write(struct file *file,
463         const char __user *buffer, size_t count, loff_t *pos)
464 {
465         cpumask_var_t new_value;
466         int err;
467
468         if (!alloc_cpumask_var(&new_value, GFP_KERNEL))
469                 return -ENOMEM;
470
471         err = cpumask_parse_user(buffer, count, new_value);
472         if (!err) {
473                 cpumask_copy(prof_cpu_mask, new_value);
474                 err = count;
475         }
476         free_cpumask_var(new_value);
477         return err;
478 }
479
480 static const struct file_operations prof_cpu_mask_proc_fops = {
481         .open           = prof_cpu_mask_proc_open,
482         .read           = seq_read,
483         .llseek         = seq_lseek,
484         .release        = single_release,
485         .write          = prof_cpu_mask_proc_write,
486 };
487
488 void create_prof_cpu_mask(struct proc_dir_entry *root_irq_dir)
489 {
490         /* create /proc/irq/prof_cpu_mask */
491         proc_create("prof_cpu_mask", 0600, root_irq_dir, &prof_cpu_mask_proc_fops);
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         .llseek         = default_llseek,
559 };
560
561 #ifdef CONFIG_SMP
562 static void profile_nop(void *unused)
563 {
564 }
565
566 static int create_hash_tables(void)
567 {
568         int cpu;
569
570         for_each_online_cpu(cpu) {
571                 int node = cpu_to_mem(cpu);
572                 struct page *page;
573
574                 page = alloc_pages_exact_node(node,
575                                 GFP_KERNEL | __GFP_ZERO | GFP_THISNODE,
576                                 0);
577                 if (!page)
578                         goto out_cleanup;
579                 per_cpu(cpu_profile_hits, cpu)[1]
580                                 = (struct profile_hit *)page_address(page);
581                 page = alloc_pages_exact_node(node,
582                                 GFP_KERNEL | __GFP_ZERO | GFP_THISNODE,
583                                 0);
584                 if (!page)
585                         goto out_cleanup;
586                 per_cpu(cpu_profile_hits, cpu)[0]
587                                 = (struct profile_hit *)page_address(page);
588         }
589         return 0;
590 out_cleanup:
591         prof_on = 0;
592         smp_mb();
593         on_each_cpu(profile_nop, NULL, 1);
594         for_each_online_cpu(cpu) {
595                 struct page *page;
596
597                 if (per_cpu(cpu_profile_hits, cpu)[0]) {
598                         page = virt_to_page(per_cpu(cpu_profile_hits, cpu)[0]);
599                         per_cpu(cpu_profile_hits, cpu)[0] = NULL;
600                         __free_page(page);
601                 }
602                 if (per_cpu(cpu_profile_hits, cpu)[1]) {
603                         page = virt_to_page(per_cpu(cpu_profile_hits, cpu)[1]);
604                         per_cpu(cpu_profile_hits, cpu)[1] = NULL;
605                         __free_page(page);
606                 }
607         }
608         return -1;
609 }
610 #else
611 #define create_hash_tables()                    ({ 0; })
612 #endif
613
614 int __ref create_proc_profile(void) /* false positive from hotcpu_notifier */
615 {
616         struct proc_dir_entry *entry;
617
618         if (!prof_on)
619                 return 0;
620         if (create_hash_tables())
621                 return -ENOMEM;
622         entry = proc_create("profile", S_IWUSR | S_IRUGO,
623                             NULL, &proc_profile_operations);
624         if (!entry)
625                 return 0;
626         entry->size = (1+prof_len) * sizeof(atomic_t);
627         hotcpu_notifier(profile_cpu_callback, 0);
628         return 0;
629 }
630 module_init(create_proc_profile);
631 #endif /* CONFIG_PROC_FS */