x86/ioapic: Cleanup the timer_works() irqflags mess
[linux-2.6-microblaze.git] / kernel / profile.c
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  *  linux/kernel/profile.c
4  *  Simple profiling. Manages a direct-mapped profile hit count buffer,
5  *  with configurable resolution, support for restricting the cpus on
6  *  which profiling is done, and switching between cpu time and
7  *  schedule() calls via kernel command line parameters passed at boot.
8  *
9  *  Scheduler profiling support, Arjan van de Ven and Ingo Molnar,
10  *      Red Hat, July 2004
11  *  Consolidation of architecture support code for profiling,
12  *      Nadia Yvette Chambers, Oracle, July 2004
13  *  Amortized hit count accounting via per-cpu open-addressed hashtables
14  *      to resolve timer interrupt livelocks, Nadia Yvette Chambers,
15  *      Oracle, 2004
16  */
17
18 #include <linux/export.h>
19 #include <linux/profile.h>
20 #include <linux/memblock.h>
21 #include <linux/notifier.h>
22 #include <linux/mm.h>
23 #include <linux/cpumask.h>
24 #include <linux/cpu.h>
25 #include <linux/highmem.h>
26 #include <linux/mutex.h>
27 #include <linux/slab.h>
28 #include <linux/vmalloc.h>
29 #include <linux/sched/stat.h>
30
31 #include <asm/sections.h>
32 #include <asm/irq_regs.h>
33 #include <asm/ptrace.h>
34
35 struct profile_hit {
36         u32 pc, hits;
37 };
38 #define PROFILE_GRPSHIFT        3
39 #define PROFILE_GRPSZ           (1 << PROFILE_GRPSHIFT)
40 #define NR_PROFILE_HIT          (PAGE_SIZE/sizeof(struct profile_hit))
41 #define NR_PROFILE_GRP          (NR_PROFILE_HIT/PROFILE_GRPSZ)
42
43 static atomic_t *prof_buffer;
44 static unsigned long prof_len, prof_shift;
45
46 int prof_on __read_mostly;
47 EXPORT_SYMBOL_GPL(prof_on);
48
49 static cpumask_var_t prof_cpu_mask;
50 #if defined(CONFIG_SMP) && defined(CONFIG_PROC_FS)
51 static DEFINE_PER_CPU(struct profile_hit *[2], cpu_profile_hits);
52 static DEFINE_PER_CPU(int, cpu_profile_flip);
53 static DEFINE_MUTEX(profile_flip_mutex);
54 #endif /* CONFIG_SMP */
55
56 int profile_setup(char *str)
57 {
58         static const char schedstr[] = "schedule";
59         static const char sleepstr[] = "sleep";
60         static const char kvmstr[] = "kvm";
61         int par;
62
63         if (!strncmp(str, sleepstr, strlen(sleepstr))) {
64 #ifdef CONFIG_SCHEDSTATS
65                 force_schedstat_enabled();
66                 prof_on = SLEEP_PROFILING;
67                 if (str[strlen(sleepstr)] == ',')
68                         str += strlen(sleepstr) + 1;
69                 if (get_option(&str, &par))
70                         prof_shift = par;
71                 pr_info("kernel sleep profiling enabled (shift: %ld)\n",
72                         prof_shift);
73 #else
74                 pr_warn("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                 pr_info("kernel schedule profiling enabled (shift: %ld)\n",
83                         prof_shift);
84         } else if (!strncmp(str, kvmstr, strlen(kvmstr))) {
85                 prof_on = KVM_PROFILING;
86                 if (str[strlen(kvmstr)] == ',')
87                         str += strlen(kvmstr) + 1;
88                 if (get_option(&str, &par))
89                         prof_shift = par;
90                 pr_info("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                 pr_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 #if defined(CONFIG_SMP) && defined(CONFIG_PROC_FS)
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 profile_dead_cpu(unsigned int cpu)
335 {
336         struct page *page;
337         int i;
338
339         if (cpumask_available(prof_cpu_mask))
340                 cpumask_clear_cpu(cpu, prof_cpu_mask);
341
342         for (i = 0; i < 2; i++) {
343                 if (per_cpu(cpu_profile_hits, cpu)[i]) {
344                         page = virt_to_page(per_cpu(cpu_profile_hits, cpu)[i]);
345                         per_cpu(cpu_profile_hits, cpu)[i] = NULL;
346                         __free_page(page);
347                 }
348         }
349         return 0;
350 }
351
352 static int profile_prepare_cpu(unsigned int cpu)
353 {
354         int i, node = cpu_to_mem(cpu);
355         struct page *page;
356
357         per_cpu(cpu_profile_flip, cpu) = 0;
358
359         for (i = 0; i < 2; i++) {
360                 if (per_cpu(cpu_profile_hits, cpu)[i])
361                         continue;
362
363                 page = __alloc_pages_node(node, GFP_KERNEL | __GFP_ZERO, 0);
364                 if (!page) {
365                         profile_dead_cpu(cpu);
366                         return -ENOMEM;
367                 }
368                 per_cpu(cpu_profile_hits, cpu)[i] = page_address(page);
369
370         }
371         return 0;
372 }
373
374 static int profile_online_cpu(unsigned int cpu)
375 {
376         if (cpumask_available(prof_cpu_mask))
377                 cpumask_set_cpu(cpu, prof_cpu_mask);
378
379         return 0;
380 }
381
382 #else /* !CONFIG_SMP */
383 #define profile_flip_buffers()          do { } while (0)
384 #define profile_discard_flip_buffers()  do { } while (0)
385
386 static void do_profile_hits(int type, void *__pc, unsigned int nr_hits)
387 {
388         unsigned long pc;
389         pc = ((unsigned long)__pc - (unsigned long)_stext) >> prof_shift;
390         atomic_add(nr_hits, &prof_buffer[min(pc, prof_len - 1)]);
391 }
392 #endif /* !CONFIG_SMP */
393
394 void profile_hits(int type, void *__pc, unsigned int nr_hits)
395 {
396         if (prof_on != type || !prof_buffer)
397                 return;
398         do_profile_hits(type, __pc, nr_hits);
399 }
400 EXPORT_SYMBOL_GPL(profile_hits);
401
402 void profile_tick(int type)
403 {
404         struct pt_regs *regs = get_irq_regs();
405
406         if (!user_mode(regs) && cpumask_available(prof_cpu_mask) &&
407             cpumask_test_cpu(smp_processor_id(), prof_cpu_mask))
408                 profile_hit(type, (void *)profile_pc(regs));
409 }
410
411 #ifdef CONFIG_PROC_FS
412 #include <linux/proc_fs.h>
413 #include <linux/seq_file.h>
414 #include <linux/uaccess.h>
415
416 static int prof_cpu_mask_proc_show(struct seq_file *m, void *v)
417 {
418         seq_printf(m, "%*pb\n", cpumask_pr_args(prof_cpu_mask));
419         return 0;
420 }
421
422 static int prof_cpu_mask_proc_open(struct inode *inode, struct file *file)
423 {
424         return single_open(file, prof_cpu_mask_proc_show, NULL);
425 }
426
427 static ssize_t prof_cpu_mask_proc_write(struct file *file,
428         const char __user *buffer, size_t count, loff_t *pos)
429 {
430         cpumask_var_t new_value;
431         int err;
432
433         if (!alloc_cpumask_var(&new_value, GFP_KERNEL))
434                 return -ENOMEM;
435
436         err = cpumask_parse_user(buffer, count, new_value);
437         if (!err) {
438                 cpumask_copy(prof_cpu_mask, new_value);
439                 err = count;
440         }
441         free_cpumask_var(new_value);
442         return err;
443 }
444
445 static const struct proc_ops prof_cpu_mask_proc_ops = {
446         .proc_open      = prof_cpu_mask_proc_open,
447         .proc_read      = seq_read,
448         .proc_lseek     = seq_lseek,
449         .proc_release   = single_release,
450         .proc_write     = prof_cpu_mask_proc_write,
451 };
452
453 void create_prof_cpu_mask(void)
454 {
455         /* create /proc/irq/prof_cpu_mask */
456         proc_create("irq/prof_cpu_mask", 0600, NULL, &prof_cpu_mask_proc_ops);
457 }
458
459 /*
460  * This function accesses profiling information. The returned data is
461  * binary: the sampling step and the actual contents of the profile
462  * buffer. Use of the program readprofile is recommended in order to
463  * get meaningful info out of these data.
464  */
465 static ssize_t
466 read_profile(struct file *file, char __user *buf, size_t count, loff_t *ppos)
467 {
468         unsigned long p = *ppos;
469         ssize_t read;
470         char *pnt;
471         unsigned int sample_step = 1 << prof_shift;
472
473         profile_flip_buffers();
474         if (p >= (prof_len+1)*sizeof(unsigned int))
475                 return 0;
476         if (count > (prof_len+1)*sizeof(unsigned int) - p)
477                 count = (prof_len+1)*sizeof(unsigned int) - p;
478         read = 0;
479
480         while (p < sizeof(unsigned int) && count > 0) {
481                 if (put_user(*((char *)(&sample_step)+p), buf))
482                         return -EFAULT;
483                 buf++; p++; count--; read++;
484         }
485         pnt = (char *)prof_buffer + p - sizeof(atomic_t);
486         if (copy_to_user(buf, (void *)pnt, count))
487                 return -EFAULT;
488         read += count;
489         *ppos += read;
490         return read;
491 }
492
493 /*
494  * Writing to /proc/profile resets the counters
495  *
496  * Writing a 'profiling multiplier' value into it also re-sets the profiling
497  * interrupt frequency, on architectures that support this.
498  */
499 static ssize_t write_profile(struct file *file, const char __user *buf,
500                              size_t count, loff_t *ppos)
501 {
502 #ifdef CONFIG_SMP
503         extern int setup_profiling_timer(unsigned int multiplier);
504
505         if (count == sizeof(int)) {
506                 unsigned int multiplier;
507
508                 if (copy_from_user(&multiplier, buf, sizeof(int)))
509                         return -EFAULT;
510
511                 if (setup_profiling_timer(multiplier))
512                         return -EINVAL;
513         }
514 #endif
515         profile_discard_flip_buffers();
516         memset(prof_buffer, 0, prof_len * sizeof(atomic_t));
517         return count;
518 }
519
520 static const struct proc_ops profile_proc_ops = {
521         .proc_read      = read_profile,
522         .proc_write     = write_profile,
523         .proc_lseek     = default_llseek,
524 };
525
526 int __ref create_proc_profile(void)
527 {
528         struct proc_dir_entry *entry;
529 #ifdef CONFIG_SMP
530         enum cpuhp_state online_state;
531 #endif
532
533         int err = 0;
534
535         if (!prof_on)
536                 return 0;
537 #ifdef CONFIG_SMP
538         err = cpuhp_setup_state(CPUHP_PROFILE_PREPARE, "PROFILE_PREPARE",
539                                 profile_prepare_cpu, profile_dead_cpu);
540         if (err)
541                 return err;
542
543         err = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "AP_PROFILE_ONLINE",
544                                 profile_online_cpu, NULL);
545         if (err < 0)
546                 goto err_state_prep;
547         online_state = err;
548         err = 0;
549 #endif
550         entry = proc_create("profile", S_IWUSR | S_IRUGO,
551                             NULL, &profile_proc_ops);
552         if (!entry)
553                 goto err_state_onl;
554         proc_set_size(entry, (1 + prof_len) * sizeof(atomic_t));
555
556         return err;
557 err_state_onl:
558 #ifdef CONFIG_SMP
559         cpuhp_remove_state(online_state);
560 err_state_prep:
561         cpuhp_remove_state(CPUHP_PROFILE_PREPARE);
562 #endif
563         return err;
564 }
565 subsys_initcall(create_proc_profile);
566 #endif /* CONFIG_PROC_FS */