audit: fix info leak in AUDIT_GET requests
[linux-3.10.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  *      Nadia Yvette Chambers, Oracle, July 2004
12  *  Amortized hit count accounting via per-cpu open-addressed hashtables
13  *      to resolve timer interrupt livelocks, Nadia Yvette Chambers,
14  *      Oracle, 2004
15  */
16
17 #include <linux/export.h>
18 #include <linux/profile.h>
19 #include <linux/bootmem.h>
20 #include <linux/notifier.h>
21 #include <linux/mm.h>
22 #include <linux/cpumask.h>
23 #include <linux/cpu.h>
24 #include <linux/highmem.h>
25 #include <linux/mutex.h>
26 #include <linux/slab.h>
27 #include <linux/vmalloc.h>
28 #include <asm/sections.h>
29 #include <asm/irq_regs.h>
30 #include <asm/ptrace.h>
31
32 struct profile_hit {
33         u32 pc, hits;
34 };
35 #define PROFILE_GRPSHIFT        3
36 #define PROFILE_GRPSZ           (1 << PROFILE_GRPSHIFT)
37 #define NR_PROFILE_HIT          (PAGE_SIZE/sizeof(struct profile_hit))
38 #define NR_PROFILE_GRP          (NR_PROFILE_HIT/PROFILE_GRPSZ)
39
40 static atomic_t *prof_buffer;
41 static unsigned long prof_len, prof_shift;
42
43 int prof_on __read_mostly;
44 EXPORT_SYMBOL_GPL(prof_on);
45
46 static cpumask_var_t prof_cpu_mask;
47 #ifdef CONFIG_SMP
48 static DEFINE_PER_CPU(struct profile_hit *[2], cpu_profile_hits);
49 static DEFINE_PER_CPU(int, cpu_profile_flip);
50 static DEFINE_MUTEX(profile_flip_mutex);
51 #endif /* CONFIG_SMP */
52
53 int profile_setup(char *str)
54 {
55         static char schedstr[] = "schedule";
56         static char sleepstr[] = "sleep";
57         static char kvmstr[] = "kvm";
58         int par;
59
60         if (!strncmp(str, sleepstr, strlen(sleepstr))) {
61 #ifdef CONFIG_SCHEDSTATS
62                 prof_on = SLEEP_PROFILING;
63                 if (str[strlen(sleepstr)] == ',')
64                         str += strlen(sleepstr) + 1;
65                 if (get_option(&str, &par))
66                         prof_shift = par;
67                 printk(KERN_INFO
68                         "kernel sleep profiling enabled (shift: %ld)\n",
69                         prof_shift);
70 #else
71                 printk(KERN_WARNING
72                         "kernel sleep profiling requires CONFIG_SCHEDSTATS\n");
73 #endif /* CONFIG_SCHEDSTATS */
74         } else if (!strncmp(str, schedstr, strlen(schedstr))) {
75                 prof_on = SCHED_PROFILING;
76                 if (str[strlen(schedstr)] == ',')
77                         str += strlen(schedstr) + 1;
78                 if (get_option(&str, &par))
79                         prof_shift = par;
80                 printk(KERN_INFO
81                         "kernel schedule profiling enabled (shift: %ld)\n",
82                         prof_shift);
83         } else if (!strncmp(str, kvmstr, strlen(kvmstr))) {
84                 prof_on = KVM_PROFILING;
85                 if (str[strlen(kvmstr)] == ',')
86                         str += strlen(kvmstr) + 1;
87                 if (get_option(&str, &par))
88                         prof_shift = par;
89                 printk(KERN_INFO
90                         "kernel KVM profiling enabled (shift: %ld)\n",
91                         prof_shift);
92         } else if (get_option(&str, &par)) {
93                 prof_shift = par;
94                 prof_on = CPU_PROFILING;
95                 printk(KERN_INFO "kernel profiling enabled (shift: %ld)\n",
96                         prof_shift);
97         }
98         return 1;
99 }
100 __setup("profile=", profile_setup);
101
102
103 int __ref profile_init(void)
104 {
105         int buffer_bytes;
106         if (!prof_on)
107                 return 0;
108
109         /* only text is profiled */
110         prof_len = (_etext - _stext) >> prof_shift;
111         buffer_bytes = prof_len*sizeof(atomic_t);
112
113         if (!alloc_cpumask_var(&prof_cpu_mask, GFP_KERNEL))
114                 return -ENOMEM;
115
116         cpumask_copy(prof_cpu_mask, cpu_possible_mask);
117
118         prof_buffer = kzalloc(buffer_bytes, GFP_KERNEL|__GFP_NOWARN);
119         if (prof_buffer)
120                 return 0;
121
122         prof_buffer = alloc_pages_exact(buffer_bytes,
123                                         GFP_KERNEL|__GFP_ZERO|__GFP_NOWARN);
124         if (prof_buffer)
125                 return 0;
126
127         prof_buffer = vzalloc(buffer_bytes);
128         if (prof_buffer)
129                 return 0;
130
131         free_cpumask_var(prof_cpu_mask);
132         return -ENOMEM;
133 }
134
135 /* Profile event notifications */
136
137 static BLOCKING_NOTIFIER_HEAD(task_exit_notifier);
138 static ATOMIC_NOTIFIER_HEAD(task_free_notifier);
139 static BLOCKING_NOTIFIER_HEAD(munmap_notifier);
140
141 void profile_task_exit(struct task_struct *task)
142 {
143         blocking_notifier_call_chain(&task_exit_notifier, 0, task);
144 }
145
146 int profile_handoff_task(struct task_struct *task)
147 {
148         int ret;
149         ret = atomic_notifier_call_chain(&task_free_notifier, 0, task);
150         return (ret == NOTIFY_OK) ? 1 : 0;
151 }
152
153 void profile_munmap(unsigned long addr)
154 {
155         blocking_notifier_call_chain(&munmap_notifier, 0, (void *)addr);
156 }
157
158 int task_handoff_register(struct notifier_block *n)
159 {
160         return atomic_notifier_chain_register(&task_free_notifier, n);
161 }
162 EXPORT_SYMBOL_GPL(task_handoff_register);
163
164 int task_handoff_unregister(struct notifier_block *n)
165 {
166         return atomic_notifier_chain_unregister(&task_free_notifier, n);
167 }
168 EXPORT_SYMBOL_GPL(task_handoff_unregister);
169
170 int profile_event_register(enum profile_type type, struct notifier_block *n)
171 {
172         int err = -EINVAL;
173
174         switch (type) {
175         case PROFILE_TASK_EXIT:
176                 err = blocking_notifier_chain_register(
177                                 &task_exit_notifier, n);
178                 break;
179         case PROFILE_MUNMAP:
180                 err = blocking_notifier_chain_register(
181                                 &munmap_notifier, n);
182                 break;
183         }
184
185         return err;
186 }
187 EXPORT_SYMBOL_GPL(profile_event_register);
188
189 int profile_event_unregister(enum profile_type type, struct notifier_block *n)
190 {
191         int err = -EINVAL;
192
193         switch (type) {
194         case PROFILE_TASK_EXIT:
195                 err = blocking_notifier_chain_unregister(
196                                 &task_exit_notifier, n);
197                 break;
198         case PROFILE_MUNMAP:
199                 err = blocking_notifier_chain_unregister(
200                                 &munmap_notifier, n);
201                 break;
202         }
203
204         return err;
205 }
206 EXPORT_SYMBOL_GPL(profile_event_unregister);
207
208 #ifdef CONFIG_SMP
209 /*
210  * Each cpu has a pair of open-addressed hashtables for pending
211  * profile hits. read_profile() IPI's all cpus to request them
212  * to flip buffers and flushes their contents to prof_buffer itself.
213  * Flip requests are serialized by the profile_flip_mutex. The sole
214  * use of having a second hashtable is for avoiding cacheline
215  * contention that would otherwise happen during flushes of pending
216  * profile hits required for the accuracy of reported profile hits
217  * and so resurrect the interrupt livelock issue.
218  *
219  * The open-addressed hashtables are indexed by profile buffer slot
220  * and hold the number of pending hits to that profile buffer slot on
221  * a cpu in an entry. When the hashtable overflows, all pending hits
222  * are accounted to their corresponding profile buffer slots with
223  * atomic_add() and the hashtable emptied. As numerous pending hits
224  * may be accounted to a profile buffer slot in a hashtable entry,
225  * this amortizes a number of atomic profile buffer increments likely
226  * to be far larger than the number of entries in the hashtable,
227  * particularly given that the number of distinct profile buffer
228  * positions to which hits are accounted during short intervals (e.g.
229  * several seconds) is usually very small. Exclusion from buffer
230  * flipping is provided by interrupt disablement (note that for
231  * SCHED_PROFILING or SLEEP_PROFILING profile_hit() may be called from
232  * process context).
233  * The hash function is meant to be lightweight as opposed to strong,
234  * and was vaguely inspired by ppc64 firmware-supported inverted
235  * pagetable hash functions, but uses a full hashtable full of finite
236  * collision chains, not just pairs of them.
237  *
238  * -- nyc
239  */
240 static void __profile_flip_buffers(void *unused)
241 {
242         int cpu = smp_processor_id();
243
244         per_cpu(cpu_profile_flip, cpu) = !per_cpu(cpu_profile_flip, cpu);
245 }
246
247 static void profile_flip_buffers(void)
248 {
249         int i, j, cpu;
250
251         mutex_lock(&profile_flip_mutex);
252         j = per_cpu(cpu_profile_flip, get_cpu());
253         put_cpu();
254         on_each_cpu(__profile_flip_buffers, NULL, 1);
255         for_each_online_cpu(cpu) {
256                 struct profile_hit *hits = per_cpu(cpu_profile_hits, cpu)[j];
257                 for (i = 0; i < NR_PROFILE_HIT; ++i) {
258                         if (!hits[i].hits) {
259                                 if (hits[i].pc)
260                                         hits[i].pc = 0;
261                                 continue;
262                         }
263                         atomic_add(hits[i].hits, &prof_buffer[hits[i].pc]);
264                         hits[i].hits = hits[i].pc = 0;
265                 }
266         }
267         mutex_unlock(&profile_flip_mutex);
268 }
269
270 static void profile_discard_flip_buffers(void)
271 {
272         int i, cpu;
273
274         mutex_lock(&profile_flip_mutex);
275         i = per_cpu(cpu_profile_flip, get_cpu());
276         put_cpu();
277         on_each_cpu(__profile_flip_buffers, NULL, 1);
278         for_each_online_cpu(cpu) {
279                 struct profile_hit *hits = per_cpu(cpu_profile_hits, cpu)[i];
280                 memset(hits, 0, NR_PROFILE_HIT*sizeof(struct profile_hit));
281         }
282         mutex_unlock(&profile_flip_mutex);
283 }
284
285 static void do_profile_hits(int type, void *__pc, unsigned int nr_hits)
286 {
287         unsigned long primary, secondary, flags, pc = (unsigned long)__pc;
288         int i, j, cpu;
289         struct profile_hit *hits;
290
291         pc = min((pc - (unsigned long)_stext) >> prof_shift, prof_len - 1);
292         i = primary = (pc & (NR_PROFILE_GRP - 1)) << PROFILE_GRPSHIFT;
293         secondary = (~(pc << 1) & (NR_PROFILE_GRP - 1)) << PROFILE_GRPSHIFT;
294         cpu = get_cpu();
295         hits = per_cpu(cpu_profile_hits, cpu)[per_cpu(cpu_profile_flip, cpu)];
296         if (!hits) {
297                 put_cpu();
298                 return;
299         }
300         /*
301          * We buffer the global profiler buffer into a per-CPU
302          * queue and thus reduce the number of global (and possibly
303          * NUMA-alien) accesses. The write-queue is self-coalescing:
304          */
305         local_irq_save(flags);
306         do {
307                 for (j = 0; j < PROFILE_GRPSZ; ++j) {
308                         if (hits[i + j].pc == pc) {
309                                 hits[i + j].hits += nr_hits;
310                                 goto out;
311                         } else if (!hits[i + j].hits) {
312                                 hits[i + j].pc = pc;
313                                 hits[i + j].hits = nr_hits;
314                                 goto out;
315                         }
316                 }
317                 i = (i + secondary) & (NR_PROFILE_HIT - 1);
318         } while (i != primary);
319
320         /*
321          * Add the current hit(s) and flush the write-queue out
322          * to the global buffer:
323          */
324         atomic_add(nr_hits, &prof_buffer[pc]);
325         for (i = 0; i < NR_PROFILE_HIT; ++i) {
326                 atomic_add(hits[i].hits, &prof_buffer[hits[i].pc]);
327                 hits[i].pc = hits[i].hits = 0;
328         }
329 out:
330         local_irq_restore(flags);
331         put_cpu();
332 }
333
334 static int __cpuinit profile_cpu_callback(struct notifier_block *info,
335                                         unsigned long action, void *__cpu)
336 {
337         int node, cpu = (unsigned long)__cpu;
338         struct page *page;
339
340         switch (action) {
341         case CPU_UP_PREPARE:
342         case CPU_UP_PREPARE_FROZEN:
343                 node = cpu_to_mem(cpu);
344                 per_cpu(cpu_profile_flip, cpu) = 0;
345                 if (!per_cpu(cpu_profile_hits, cpu)[1]) {
346                         page = alloc_pages_exact_node(node,
347                                         GFP_KERNEL | __GFP_ZERO,
348                                         0);
349                         if (!page)
350                                 return notifier_from_errno(-ENOMEM);
351                         per_cpu(cpu_profile_hits, cpu)[1] = page_address(page);
352                 }
353                 if (!per_cpu(cpu_profile_hits, cpu)[0]) {
354                         page = alloc_pages_exact_node(node,
355                                         GFP_KERNEL | __GFP_ZERO,
356                                         0);
357                         if (!page)
358                                 goto out_free;
359                         per_cpu(cpu_profile_hits, cpu)[0] = page_address(page);
360                 }
361                 break;
362 out_free:
363                 page = virt_to_page(per_cpu(cpu_profile_hits, cpu)[1]);
364                 per_cpu(cpu_profile_hits, cpu)[1] = NULL;
365                 __free_page(page);
366                 return notifier_from_errno(-ENOMEM);
367         case CPU_ONLINE:
368         case CPU_ONLINE_FROZEN:
369                 if (prof_cpu_mask != NULL)
370                         cpumask_set_cpu(cpu, prof_cpu_mask);
371                 break;
372         case CPU_UP_CANCELED:
373         case CPU_UP_CANCELED_FROZEN:
374         case CPU_DEAD:
375         case CPU_DEAD_FROZEN:
376                 if (prof_cpu_mask != NULL)
377                         cpumask_clear_cpu(cpu, prof_cpu_mask);
378                 if (per_cpu(cpu_profile_hits, cpu)[0]) {
379                         page = virt_to_page(per_cpu(cpu_profile_hits, cpu)[0]);
380                         per_cpu(cpu_profile_hits, cpu)[0] = NULL;
381                         __free_page(page);
382                 }
383                 if (per_cpu(cpu_profile_hits, cpu)[1]) {
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                 }
388                 break;
389         }
390         return NOTIFY_OK;
391 }
392 #else /* !CONFIG_SMP */
393 #define profile_flip_buffers()          do { } while (0)
394 #define profile_discard_flip_buffers()  do { } while (0)
395 #define profile_cpu_callback            NULL
396
397 static void do_profile_hits(int type, void *__pc, unsigned int nr_hits)
398 {
399         unsigned long pc;
400         pc = ((unsigned long)__pc - (unsigned long)_stext) >> prof_shift;
401         atomic_add(nr_hits, &prof_buffer[min(pc, prof_len - 1)]);
402 }
403 #endif /* !CONFIG_SMP */
404
405 void profile_hits(int type, void *__pc, unsigned int nr_hits)
406 {
407         if (prof_on != type || !prof_buffer)
408                 return;
409         do_profile_hits(type, __pc, nr_hits);
410 }
411 EXPORT_SYMBOL_GPL(profile_hits);
412
413 void profile_tick(int type)
414 {
415         struct pt_regs *regs = get_irq_regs();
416
417         if (!user_mode(regs) && prof_cpu_mask != NULL &&
418             cpumask_test_cpu(smp_processor_id(), prof_cpu_mask))
419                 profile_hit(type, (void *)profile_pc(regs));
420 }
421
422 #ifdef CONFIG_PROC_FS
423 #include <linux/proc_fs.h>
424 #include <linux/seq_file.h>
425 #include <asm/uaccess.h>
426
427 static int prof_cpu_mask_proc_show(struct seq_file *m, void *v)
428 {
429         seq_cpumask(m, prof_cpu_mask);
430         seq_putc(m, '\n');
431         return 0;
432 }
433
434 static int prof_cpu_mask_proc_open(struct inode *inode, struct file *file)
435 {
436         return single_open(file, prof_cpu_mask_proc_show, NULL);
437 }
438
439 static ssize_t prof_cpu_mask_proc_write(struct file *file,
440         const char __user *buffer, size_t count, loff_t *pos)
441 {
442         cpumask_var_t new_value;
443         int err;
444
445         if (!alloc_cpumask_var(&new_value, GFP_KERNEL))
446                 return -ENOMEM;
447
448         err = cpumask_parse_user(buffer, count, new_value);
449         if (!err) {
450                 cpumask_copy(prof_cpu_mask, new_value);
451                 err = count;
452         }
453         free_cpumask_var(new_value);
454         return err;
455 }
456
457 static const struct file_operations prof_cpu_mask_proc_fops = {
458         .open           = prof_cpu_mask_proc_open,
459         .read           = seq_read,
460         .llseek         = seq_lseek,
461         .release        = single_release,
462         .write          = prof_cpu_mask_proc_write,
463 };
464
465 void create_prof_cpu_mask(void)
466 {
467         /* create /proc/irq/prof_cpu_mask */
468         proc_create("irq/prof_cpu_mask", 0600, NULL, &prof_cpu_mask_proc_fops);
469 }
470
471 /*
472  * This function accesses profiling information. The returned data is
473  * binary: the sampling step and the actual contents of the profile
474  * buffer. Use of the program readprofile is recommended in order to
475  * get meaningful info out of these data.
476  */
477 static ssize_t
478 read_profile(struct file *file, char __user *buf, size_t count, loff_t *ppos)
479 {
480         unsigned long p = *ppos;
481         ssize_t read;
482         char *pnt;
483         unsigned int sample_step = 1 << prof_shift;
484
485         profile_flip_buffers();
486         if (p >= (prof_len+1)*sizeof(unsigned int))
487                 return 0;
488         if (count > (prof_len+1)*sizeof(unsigned int) - p)
489                 count = (prof_len+1)*sizeof(unsigned int) - p;
490         read = 0;
491
492         while (p < sizeof(unsigned int) && count > 0) {
493                 if (put_user(*((char *)(&sample_step)+p), buf))
494                         return -EFAULT;
495                 buf++; p++; count--; read++;
496         }
497         pnt = (char *)prof_buffer + p - sizeof(atomic_t);
498         if (copy_to_user(buf, (void *)pnt, count))
499                 return -EFAULT;
500         read += count;
501         *ppos += read;
502         return read;
503 }
504
505 /*
506  * Writing to /proc/profile resets the counters
507  *
508  * Writing a 'profiling multiplier' value into it also re-sets the profiling
509  * interrupt frequency, on architectures that support this.
510  */
511 static ssize_t write_profile(struct file *file, const char __user *buf,
512                              size_t count, loff_t *ppos)
513 {
514 #ifdef CONFIG_SMP
515         extern int setup_profiling_timer(unsigned int multiplier);
516
517         if (count == sizeof(int)) {
518                 unsigned int multiplier;
519
520                 if (copy_from_user(&multiplier, buf, sizeof(int)))
521                         return -EFAULT;
522
523                 if (setup_profiling_timer(multiplier))
524                         return -EINVAL;
525         }
526 #endif
527         profile_discard_flip_buffers();
528         memset(prof_buffer, 0, prof_len * sizeof(atomic_t));
529         return count;
530 }
531
532 static const struct file_operations proc_profile_operations = {
533         .read           = read_profile,
534         .write          = write_profile,
535         .llseek         = default_llseek,
536 };
537
538 #ifdef CONFIG_SMP
539 static void profile_nop(void *unused)
540 {
541 }
542
543 static int create_hash_tables(void)
544 {
545         int cpu;
546
547         for_each_online_cpu(cpu) {
548                 int node = cpu_to_mem(cpu);
549                 struct page *page;
550
551                 page = alloc_pages_exact_node(node,
552                                 GFP_KERNEL | __GFP_ZERO | GFP_THISNODE,
553                                 0);
554                 if (!page)
555                         goto out_cleanup;
556                 per_cpu(cpu_profile_hits, cpu)[1]
557                                 = (struct profile_hit *)page_address(page);
558                 page = alloc_pages_exact_node(node,
559                                 GFP_KERNEL | __GFP_ZERO | GFP_THISNODE,
560                                 0);
561                 if (!page)
562                         goto out_cleanup;
563                 per_cpu(cpu_profile_hits, cpu)[0]
564                                 = (struct profile_hit *)page_address(page);
565         }
566         return 0;
567 out_cleanup:
568         prof_on = 0;
569         smp_mb();
570         on_each_cpu(profile_nop, NULL, 1);
571         for_each_online_cpu(cpu) {
572                 struct page *page;
573
574                 if (per_cpu(cpu_profile_hits, cpu)[0]) {
575                         page = virt_to_page(per_cpu(cpu_profile_hits, cpu)[0]);
576                         per_cpu(cpu_profile_hits, cpu)[0] = NULL;
577                         __free_page(page);
578                 }
579                 if (per_cpu(cpu_profile_hits, cpu)[1]) {
580                         page = virt_to_page(per_cpu(cpu_profile_hits, cpu)[1]);
581                         per_cpu(cpu_profile_hits, cpu)[1] = NULL;
582                         __free_page(page);
583                 }
584         }
585         return -1;
586 }
587 #else
588 #define create_hash_tables()                    ({ 0; })
589 #endif
590
591 int __ref create_proc_profile(void) /* false positive from hotcpu_notifier */
592 {
593         struct proc_dir_entry *entry;
594
595         if (!prof_on)
596                 return 0;
597         if (create_hash_tables())
598                 return -ENOMEM;
599         entry = proc_create("profile", S_IWUSR | S_IRUGO,
600                             NULL, &proc_profile_operations);
601         if (!entry)
602                 return 0;
603         proc_set_size(entry, (1 + prof_len) * sizeof(atomic_t));
604         hotcpu_notifier(profile_cpu_callback, 0);
605         return 0;
606 }
607 module_init(create_proc_profile);
608 #endif /* CONFIG_PROC_FS */