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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
35struct 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
43static atomic_t *prof_buffer;
44static unsigned long prof_len, prof_shift;
45
46int prof_on __read_mostly;
47EXPORT_SYMBOL_GPL(prof_on);
48
49static cpumask_var_t prof_cpu_mask;
50#if defined(CONFIG_SMP) && defined(CONFIG_PROC_FS)
51static DEFINE_PER_CPU(struct profile_hit *[2], cpu_profile_hits);
52static DEFINE_PER_CPU(int, cpu_profile_flip);
53static DEFINE_MUTEX(profile_flip_mutex);
54#endif /* CONFIG_SMP */
55
56int 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
103int __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
137static BLOCKING_NOTIFIER_HEAD(task_exit_notifier);
138static ATOMIC_NOTIFIER_HEAD(task_free_notifier);
139static BLOCKING_NOTIFIER_HEAD(munmap_notifier);
140
141void profile_task_exit(struct task_struct *task)
142{
143 blocking_notifier_call_chain(&task_exit_notifier, 0, task);
144}
145
146int 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
153void profile_munmap(unsigned long addr)
154{
155 blocking_notifier_call_chain(&munmap_notifier, 0, (void *)addr);
156}
157
158int task_handoff_register(struct notifier_block *n)
159{
160 return atomic_notifier_chain_register(&task_free_notifier, n);
161}
162EXPORT_SYMBOL_GPL(task_handoff_register);
163
164int task_handoff_unregister(struct notifier_block *n)
165{
166 return atomic_notifier_chain_unregister(&task_free_notifier, n);
167}
168EXPORT_SYMBOL_GPL(task_handoff_unregister);
169
170int 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}
187EXPORT_SYMBOL_GPL(profile_event_register);
188
189int 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}
206EXPORT_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 */
240static 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
247static 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
270static 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
285static 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 }
329out:
330 local_irq_restore(flags);
331 put_cpu();
332}
333
334static int profile_dead_cpu(unsigned int cpu)
335{
336 struct page *page;
337 int i;
338
339 if (prof_cpu_mask != NULL)
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
352static 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
374static int profile_online_cpu(unsigned int cpu)
375{
376 if (prof_cpu_mask != NULL)
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
386static 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
394void 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}
400EXPORT_SYMBOL_GPL(profile_hits);
401
402void profile_tick(int type)
403{
404 struct pt_regs *regs = get_irq_regs();
405
406 if (!user_mode(regs) && prof_cpu_mask != NULL &&
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
416static 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
422static 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
427static 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
445static const struct file_operations prof_cpu_mask_proc_fops = {
446 .open = prof_cpu_mask_proc_open,
447 .read = seq_read,
448 .llseek = seq_lseek,
449 .release = single_release,
450 .write = prof_cpu_mask_proc_write,
451};
452
453void 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_fops);
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 */
465static ssize_t
466read_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 */
499static 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
520static const struct file_operations proc_profile_operations = {
521 .read = read_profile,
522 .write = write_profile,
523 .llseek = default_llseek,
524};
525
526int __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, &proc_profile_operations);
552 if (!entry)
553 goto err_state_onl;
554 proc_set_size(entry, (1 + prof_len) * sizeof(atomic_t));
555
556 return err;
557err_state_onl:
558#ifdef CONFIG_SMP
559 cpuhp_remove_state(online_state);
560err_state_prep:
561 cpuhp_remove_state(CPUHP_PROFILE_PREPARE);
562#endif
563 return err;
564}
565subsys_initcall(create_proc_profile);
566#endif /* CONFIG_PROC_FS */
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
35struct 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
43static atomic_t *prof_buffer;
44static unsigned long prof_len;
45static unsigned short int prof_shift;
46
47int prof_on __read_mostly;
48EXPORT_SYMBOL_GPL(prof_on);
49
50static cpumask_var_t prof_cpu_mask;
51#if defined(CONFIG_SMP) && defined(CONFIG_PROC_FS)
52static DEFINE_PER_CPU(struct profile_hit *[2], cpu_profile_hits);
53static DEFINE_PER_CPU(int, cpu_profile_flip);
54static DEFINE_MUTEX(profile_flip_mutex);
55#endif /* CONFIG_SMP */
56
57int profile_setup(char *str)
58{
59 static const char schedstr[] = "schedule";
60 static const char sleepstr[] = "sleep";
61 static const char kvmstr[] = "kvm";
62 int par;
63
64 if (!strncmp(str, sleepstr, strlen(sleepstr))) {
65#ifdef CONFIG_SCHEDSTATS
66 force_schedstat_enabled();
67 prof_on = SLEEP_PROFILING;
68 if (str[strlen(sleepstr)] == ',')
69 str += strlen(sleepstr) + 1;
70 if (get_option(&str, &par))
71 prof_shift = clamp(par, 0, BITS_PER_LONG - 1);
72 pr_info("kernel sleep profiling enabled (shift: %u)\n",
73 prof_shift);
74#else
75 pr_warn("kernel sleep profiling requires CONFIG_SCHEDSTATS\n");
76#endif /* CONFIG_SCHEDSTATS */
77 } else if (!strncmp(str, schedstr, strlen(schedstr))) {
78 prof_on = SCHED_PROFILING;
79 if (str[strlen(schedstr)] == ',')
80 str += strlen(schedstr) + 1;
81 if (get_option(&str, &par))
82 prof_shift = clamp(par, 0, BITS_PER_LONG - 1);
83 pr_info("kernel schedule profiling enabled (shift: %u)\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 = clamp(par, 0, BITS_PER_LONG - 1);
91 pr_info("kernel KVM profiling enabled (shift: %u)\n",
92 prof_shift);
93 } else if (get_option(&str, &par)) {
94 prof_shift = clamp(par, 0, BITS_PER_LONG - 1);
95 prof_on = CPU_PROFILING;
96 pr_info("kernel profiling enabled (shift: %u)\n",
97 prof_shift);
98 }
99 return 1;
100}
101__setup("profile=", profile_setup);
102
103
104int __ref profile_init(void)
105{
106 int buffer_bytes;
107 if (!prof_on)
108 return 0;
109
110 /* only text is profiled */
111 prof_len = (_etext - _stext) >> prof_shift;
112 buffer_bytes = prof_len*sizeof(atomic_t);
113
114 if (!alloc_cpumask_var(&prof_cpu_mask, GFP_KERNEL))
115 return -ENOMEM;
116
117 cpumask_copy(prof_cpu_mask, cpu_possible_mask);
118
119 prof_buffer = kzalloc(buffer_bytes, GFP_KERNEL|__GFP_NOWARN);
120 if (prof_buffer)
121 return 0;
122
123 prof_buffer = alloc_pages_exact(buffer_bytes,
124 GFP_KERNEL|__GFP_ZERO|__GFP_NOWARN);
125 if (prof_buffer)
126 return 0;
127
128 prof_buffer = vzalloc(buffer_bytes);
129 if (prof_buffer)
130 return 0;
131
132 free_cpumask_var(prof_cpu_mask);
133 return -ENOMEM;
134}
135
136/* Profile event notifications */
137
138static BLOCKING_NOTIFIER_HEAD(task_exit_notifier);
139static ATOMIC_NOTIFIER_HEAD(task_free_notifier);
140static BLOCKING_NOTIFIER_HEAD(munmap_notifier);
141
142void profile_task_exit(struct task_struct *task)
143{
144 blocking_notifier_call_chain(&task_exit_notifier, 0, task);
145}
146
147int profile_handoff_task(struct task_struct *task)
148{
149 int ret;
150 ret = atomic_notifier_call_chain(&task_free_notifier, 0, task);
151 return (ret == NOTIFY_OK) ? 1 : 0;
152}
153
154void profile_munmap(unsigned long addr)
155{
156 blocking_notifier_call_chain(&munmap_notifier, 0, (void *)addr);
157}
158
159int task_handoff_register(struct notifier_block *n)
160{
161 return atomic_notifier_chain_register(&task_free_notifier, n);
162}
163EXPORT_SYMBOL_GPL(task_handoff_register);
164
165int task_handoff_unregister(struct notifier_block *n)
166{
167 return atomic_notifier_chain_unregister(&task_free_notifier, n);
168}
169EXPORT_SYMBOL_GPL(task_handoff_unregister);
170
171int profile_event_register(enum profile_type type, struct notifier_block *n)
172{
173 int err = -EINVAL;
174
175 switch (type) {
176 case PROFILE_TASK_EXIT:
177 err = blocking_notifier_chain_register(
178 &task_exit_notifier, n);
179 break;
180 case PROFILE_MUNMAP:
181 err = blocking_notifier_chain_register(
182 &munmap_notifier, n);
183 break;
184 }
185
186 return err;
187}
188EXPORT_SYMBOL_GPL(profile_event_register);
189
190int profile_event_unregister(enum profile_type type, struct notifier_block *n)
191{
192 int err = -EINVAL;
193
194 switch (type) {
195 case PROFILE_TASK_EXIT:
196 err = blocking_notifier_chain_unregister(
197 &task_exit_notifier, n);
198 break;
199 case PROFILE_MUNMAP:
200 err = blocking_notifier_chain_unregister(
201 &munmap_notifier, n);
202 break;
203 }
204
205 return err;
206}
207EXPORT_SYMBOL_GPL(profile_event_unregister);
208
209#if defined(CONFIG_SMP) && defined(CONFIG_PROC_FS)
210/*
211 * Each cpu has a pair of open-addressed hashtables for pending
212 * profile hits. read_profile() IPI's all cpus to request them
213 * to flip buffers and flushes their contents to prof_buffer itself.
214 * Flip requests are serialized by the profile_flip_mutex. The sole
215 * use of having a second hashtable is for avoiding cacheline
216 * contention that would otherwise happen during flushes of pending
217 * profile hits required for the accuracy of reported profile hits
218 * and so resurrect the interrupt livelock issue.
219 *
220 * The open-addressed hashtables are indexed by profile buffer slot
221 * and hold the number of pending hits to that profile buffer slot on
222 * a cpu in an entry. When the hashtable overflows, all pending hits
223 * are accounted to their corresponding profile buffer slots with
224 * atomic_add() and the hashtable emptied. As numerous pending hits
225 * may be accounted to a profile buffer slot in a hashtable entry,
226 * this amortizes a number of atomic profile buffer increments likely
227 * to be far larger than the number of entries in the hashtable,
228 * particularly given that the number of distinct profile buffer
229 * positions to which hits are accounted during short intervals (e.g.
230 * several seconds) is usually very small. Exclusion from buffer
231 * flipping is provided by interrupt disablement (note that for
232 * SCHED_PROFILING or SLEEP_PROFILING profile_hit() may be called from
233 * process context).
234 * The hash function is meant to be lightweight as opposed to strong,
235 * and was vaguely inspired by ppc64 firmware-supported inverted
236 * pagetable hash functions, but uses a full hashtable full of finite
237 * collision chains, not just pairs of them.
238 *
239 * -- nyc
240 */
241static void __profile_flip_buffers(void *unused)
242{
243 int cpu = smp_processor_id();
244
245 per_cpu(cpu_profile_flip, cpu) = !per_cpu(cpu_profile_flip, cpu);
246}
247
248static void profile_flip_buffers(void)
249{
250 int i, j, cpu;
251
252 mutex_lock(&profile_flip_mutex);
253 j = per_cpu(cpu_profile_flip, get_cpu());
254 put_cpu();
255 on_each_cpu(__profile_flip_buffers, NULL, 1);
256 for_each_online_cpu(cpu) {
257 struct profile_hit *hits = per_cpu(cpu_profile_hits, cpu)[j];
258 for (i = 0; i < NR_PROFILE_HIT; ++i) {
259 if (!hits[i].hits) {
260 if (hits[i].pc)
261 hits[i].pc = 0;
262 continue;
263 }
264 atomic_add(hits[i].hits, &prof_buffer[hits[i].pc]);
265 hits[i].hits = hits[i].pc = 0;
266 }
267 }
268 mutex_unlock(&profile_flip_mutex);
269}
270
271static void profile_discard_flip_buffers(void)
272{
273 int i, cpu;
274
275 mutex_lock(&profile_flip_mutex);
276 i = per_cpu(cpu_profile_flip, get_cpu());
277 put_cpu();
278 on_each_cpu(__profile_flip_buffers, NULL, 1);
279 for_each_online_cpu(cpu) {
280 struct profile_hit *hits = per_cpu(cpu_profile_hits, cpu)[i];
281 memset(hits, 0, NR_PROFILE_HIT*sizeof(struct profile_hit));
282 }
283 mutex_unlock(&profile_flip_mutex);
284}
285
286static void do_profile_hits(int type, void *__pc, unsigned int nr_hits)
287{
288 unsigned long primary, secondary, flags, pc = (unsigned long)__pc;
289 int i, j, cpu;
290 struct profile_hit *hits;
291
292 pc = min((pc - (unsigned long)_stext) >> prof_shift, prof_len - 1);
293 i = primary = (pc & (NR_PROFILE_GRP - 1)) << PROFILE_GRPSHIFT;
294 secondary = (~(pc << 1) & (NR_PROFILE_GRP - 1)) << PROFILE_GRPSHIFT;
295 cpu = get_cpu();
296 hits = per_cpu(cpu_profile_hits, cpu)[per_cpu(cpu_profile_flip, cpu)];
297 if (!hits) {
298 put_cpu();
299 return;
300 }
301 /*
302 * We buffer the global profiler buffer into a per-CPU
303 * queue and thus reduce the number of global (and possibly
304 * NUMA-alien) accesses. The write-queue is self-coalescing:
305 */
306 local_irq_save(flags);
307 do {
308 for (j = 0; j < PROFILE_GRPSZ; ++j) {
309 if (hits[i + j].pc == pc) {
310 hits[i + j].hits += nr_hits;
311 goto out;
312 } else if (!hits[i + j].hits) {
313 hits[i + j].pc = pc;
314 hits[i + j].hits = nr_hits;
315 goto out;
316 }
317 }
318 i = (i + secondary) & (NR_PROFILE_HIT - 1);
319 } while (i != primary);
320
321 /*
322 * Add the current hit(s) and flush the write-queue out
323 * to the global buffer:
324 */
325 atomic_add(nr_hits, &prof_buffer[pc]);
326 for (i = 0; i < NR_PROFILE_HIT; ++i) {
327 atomic_add(hits[i].hits, &prof_buffer[hits[i].pc]);
328 hits[i].pc = hits[i].hits = 0;
329 }
330out:
331 local_irq_restore(flags);
332 put_cpu();
333}
334
335static int profile_dead_cpu(unsigned int cpu)
336{
337 struct page *page;
338 int i;
339
340 if (cpumask_available(prof_cpu_mask))
341 cpumask_clear_cpu(cpu, prof_cpu_mask);
342
343 for (i = 0; i < 2; i++) {
344 if (per_cpu(cpu_profile_hits, cpu)[i]) {
345 page = virt_to_page(per_cpu(cpu_profile_hits, cpu)[i]);
346 per_cpu(cpu_profile_hits, cpu)[i] = NULL;
347 __free_page(page);
348 }
349 }
350 return 0;
351}
352
353static int profile_prepare_cpu(unsigned int cpu)
354{
355 int i, node = cpu_to_mem(cpu);
356 struct page *page;
357
358 per_cpu(cpu_profile_flip, cpu) = 0;
359
360 for (i = 0; i < 2; i++) {
361 if (per_cpu(cpu_profile_hits, cpu)[i])
362 continue;
363
364 page = __alloc_pages_node(node, GFP_KERNEL | __GFP_ZERO, 0);
365 if (!page) {
366 profile_dead_cpu(cpu);
367 return -ENOMEM;
368 }
369 per_cpu(cpu_profile_hits, cpu)[i] = page_address(page);
370
371 }
372 return 0;
373}
374
375static int profile_online_cpu(unsigned int cpu)
376{
377 if (cpumask_available(prof_cpu_mask))
378 cpumask_set_cpu(cpu, prof_cpu_mask);
379
380 return 0;
381}
382
383#else /* !CONFIG_SMP */
384#define profile_flip_buffers() do { } while (0)
385#define profile_discard_flip_buffers() do { } while (0)
386
387static void do_profile_hits(int type, void *__pc, unsigned int nr_hits)
388{
389 unsigned long pc;
390 pc = ((unsigned long)__pc - (unsigned long)_stext) >> prof_shift;
391 atomic_add(nr_hits, &prof_buffer[min(pc, prof_len - 1)]);
392}
393#endif /* !CONFIG_SMP */
394
395void profile_hits(int type, void *__pc, unsigned int nr_hits)
396{
397 if (prof_on != type || !prof_buffer)
398 return;
399 do_profile_hits(type, __pc, nr_hits);
400}
401EXPORT_SYMBOL_GPL(profile_hits);
402
403void profile_tick(int type)
404{
405 struct pt_regs *regs = get_irq_regs();
406
407 if (!user_mode(regs) && cpumask_available(prof_cpu_mask) &&
408 cpumask_test_cpu(smp_processor_id(), prof_cpu_mask))
409 profile_hit(type, (void *)profile_pc(regs));
410}
411
412#ifdef CONFIG_PROC_FS
413#include <linux/proc_fs.h>
414#include <linux/seq_file.h>
415#include <linux/uaccess.h>
416
417static int prof_cpu_mask_proc_show(struct seq_file *m, void *v)
418{
419 seq_printf(m, "%*pb\n", cpumask_pr_args(prof_cpu_mask));
420 return 0;
421}
422
423static int prof_cpu_mask_proc_open(struct inode *inode, struct file *file)
424{
425 return single_open(file, prof_cpu_mask_proc_show, NULL);
426}
427
428static ssize_t prof_cpu_mask_proc_write(struct file *file,
429 const char __user *buffer, size_t count, loff_t *pos)
430{
431 cpumask_var_t new_value;
432 int err;
433
434 if (!zalloc_cpumask_var(&new_value, GFP_KERNEL))
435 return -ENOMEM;
436
437 err = cpumask_parse_user(buffer, count, new_value);
438 if (!err) {
439 cpumask_copy(prof_cpu_mask, new_value);
440 err = count;
441 }
442 free_cpumask_var(new_value);
443 return err;
444}
445
446static const struct proc_ops prof_cpu_mask_proc_ops = {
447 .proc_open = prof_cpu_mask_proc_open,
448 .proc_read = seq_read,
449 .proc_lseek = seq_lseek,
450 .proc_release = single_release,
451 .proc_write = prof_cpu_mask_proc_write,
452};
453
454void create_prof_cpu_mask(void)
455{
456 /* create /proc/irq/prof_cpu_mask */
457 proc_create("irq/prof_cpu_mask", 0600, NULL, &prof_cpu_mask_proc_ops);
458}
459
460/*
461 * This function accesses profiling information. The returned data is
462 * binary: the sampling step and the actual contents of the profile
463 * buffer. Use of the program readprofile is recommended in order to
464 * get meaningful info out of these data.
465 */
466static ssize_t
467read_profile(struct file *file, char __user *buf, size_t count, loff_t *ppos)
468{
469 unsigned long p = *ppos;
470 ssize_t read;
471 char *pnt;
472 unsigned long sample_step = 1UL << prof_shift;
473
474 profile_flip_buffers();
475 if (p >= (prof_len+1)*sizeof(unsigned int))
476 return 0;
477 if (count > (prof_len+1)*sizeof(unsigned int) - p)
478 count = (prof_len+1)*sizeof(unsigned int) - p;
479 read = 0;
480
481 while (p < sizeof(unsigned int) && count > 0) {
482 if (put_user(*((char *)(&sample_step)+p), buf))
483 return -EFAULT;
484 buf++; p++; count--; read++;
485 }
486 pnt = (char *)prof_buffer + p - sizeof(atomic_t);
487 if (copy_to_user(buf, (void *)pnt, count))
488 return -EFAULT;
489 read += count;
490 *ppos += read;
491 return read;
492}
493
494/*
495 * Writing to /proc/profile resets the counters
496 *
497 * Writing a 'profiling multiplier' value into it also re-sets the profiling
498 * interrupt frequency, on architectures that support this.
499 */
500static ssize_t write_profile(struct file *file, const char __user *buf,
501 size_t count, loff_t *ppos)
502{
503#ifdef CONFIG_SMP
504 extern int setup_profiling_timer(unsigned int multiplier);
505
506 if (count == sizeof(int)) {
507 unsigned int multiplier;
508
509 if (copy_from_user(&multiplier, buf, sizeof(int)))
510 return -EFAULT;
511
512 if (setup_profiling_timer(multiplier))
513 return -EINVAL;
514 }
515#endif
516 profile_discard_flip_buffers();
517 memset(prof_buffer, 0, prof_len * sizeof(atomic_t));
518 return count;
519}
520
521static const struct proc_ops profile_proc_ops = {
522 .proc_read = read_profile,
523 .proc_write = write_profile,
524 .proc_lseek = default_llseek,
525};
526
527int __ref create_proc_profile(void)
528{
529 struct proc_dir_entry *entry;
530#ifdef CONFIG_SMP
531 enum cpuhp_state online_state;
532#endif
533
534 int err = 0;
535
536 if (!prof_on)
537 return 0;
538#ifdef CONFIG_SMP
539 err = cpuhp_setup_state(CPUHP_PROFILE_PREPARE, "PROFILE_PREPARE",
540 profile_prepare_cpu, profile_dead_cpu);
541 if (err)
542 return err;
543
544 err = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "AP_PROFILE_ONLINE",
545 profile_online_cpu, NULL);
546 if (err < 0)
547 goto err_state_prep;
548 online_state = err;
549 err = 0;
550#endif
551 entry = proc_create("profile", S_IWUSR | S_IRUGO,
552 NULL, &profile_proc_ops);
553 if (!entry)
554 goto err_state_onl;
555 proc_set_size(entry, (1 + prof_len) * sizeof(atomic_t));
556
557 return err;
558err_state_onl:
559#ifdef CONFIG_SMP
560 cpuhp_remove_state(online_state);
561err_state_prep:
562 cpuhp_remove_state(CPUHP_PROFILE_PREPARE);
563#endif
564 return err;
565}
566subsys_initcall(create_proc_profile);
567#endif /* CONFIG_PROC_FS */