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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/*
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 <linux/sched/stat.h>
29
30#include <asm/sections.h>
31#include <asm/irq_regs.h>
32#include <asm/ptrace.h>
33
34struct profile_hit {
35 u32 pc, hits;
36};
37#define PROFILE_GRPSHIFT 3
38#define PROFILE_GRPSZ (1 << PROFILE_GRPSHIFT)
39#define NR_PROFILE_HIT (PAGE_SIZE/sizeof(struct profile_hit))
40#define NR_PROFILE_GRP (NR_PROFILE_HIT/PROFILE_GRPSZ)
41
42static atomic_t *prof_buffer;
43static unsigned long prof_len, prof_shift;
44
45int prof_on __read_mostly;
46EXPORT_SYMBOL_GPL(prof_on);
47
48static cpumask_var_t prof_cpu_mask;
49#if defined(CONFIG_SMP) && defined(CONFIG_PROC_FS)
50static DEFINE_PER_CPU(struct profile_hit *[2], cpu_profile_hits);
51static DEFINE_PER_CPU(int, cpu_profile_flip);
52static DEFINE_MUTEX(profile_flip_mutex);
53#endif /* CONFIG_SMP */
54
55int profile_setup(char *str)
56{
57 static const char schedstr[] = "schedule";
58 static const char sleepstr[] = "sleep";
59 static const char kvmstr[] = "kvm";
60 int par;
61
62 if (!strncmp(str, sleepstr, strlen(sleepstr))) {
63#ifdef CONFIG_SCHEDSTATS
64 force_schedstat_enabled();
65 prof_on = SLEEP_PROFILING;
66 if (str[strlen(sleepstr)] == ',')
67 str += strlen(sleepstr) + 1;
68 if (get_option(&str, &par))
69 prof_shift = par;
70 pr_info("kernel sleep profiling enabled (shift: %ld)\n",
71 prof_shift);
72#else
73 pr_warn("kernel sleep profiling requires CONFIG_SCHEDSTATS\n");
74#endif /* CONFIG_SCHEDSTATS */
75 } else if (!strncmp(str, schedstr, strlen(schedstr))) {
76 prof_on = SCHED_PROFILING;
77 if (str[strlen(schedstr)] == ',')
78 str += strlen(schedstr) + 1;
79 if (get_option(&str, &par))
80 prof_shift = par;
81 pr_info("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 pr_info("kernel KVM profiling enabled (shift: %ld)\n",
90 prof_shift);
91 } else if (get_option(&str, &par)) {
92 prof_shift = par;
93 prof_on = CPU_PROFILING;
94 pr_info("kernel profiling enabled (shift: %ld)\n",
95 prof_shift);
96 }
97 return 1;
98}
99__setup("profile=", profile_setup);
100
101
102int __ref profile_init(void)
103{
104 int buffer_bytes;
105 if (!prof_on)
106 return 0;
107
108 /* only text is profiled */
109 prof_len = (_etext - _stext) >> prof_shift;
110 buffer_bytes = prof_len*sizeof(atomic_t);
111
112 if (!alloc_cpumask_var(&prof_cpu_mask, GFP_KERNEL))
113 return -ENOMEM;
114
115 cpumask_copy(prof_cpu_mask, cpu_possible_mask);
116
117 prof_buffer = kzalloc(buffer_bytes, GFP_KERNEL|__GFP_NOWARN);
118 if (prof_buffer)
119 return 0;
120
121 prof_buffer = alloc_pages_exact(buffer_bytes,
122 GFP_KERNEL|__GFP_ZERO|__GFP_NOWARN);
123 if (prof_buffer)
124 return 0;
125
126 prof_buffer = vzalloc(buffer_bytes);
127 if (prof_buffer)
128 return 0;
129
130 free_cpumask_var(prof_cpu_mask);
131 return -ENOMEM;
132}
133
134/* Profile event notifications */
135
136static BLOCKING_NOTIFIER_HEAD(task_exit_notifier);
137static ATOMIC_NOTIFIER_HEAD(task_free_notifier);
138static BLOCKING_NOTIFIER_HEAD(munmap_notifier);
139
140void profile_task_exit(struct task_struct *task)
141{
142 blocking_notifier_call_chain(&task_exit_notifier, 0, task);
143}
144
145int profile_handoff_task(struct task_struct *task)
146{
147 int ret;
148 ret = atomic_notifier_call_chain(&task_free_notifier, 0, task);
149 return (ret == NOTIFY_OK) ? 1 : 0;
150}
151
152void profile_munmap(unsigned long addr)
153{
154 blocking_notifier_call_chain(&munmap_notifier, 0, (void *)addr);
155}
156
157int task_handoff_register(struct notifier_block *n)
158{
159 return atomic_notifier_chain_register(&task_free_notifier, n);
160}
161EXPORT_SYMBOL_GPL(task_handoff_register);
162
163int task_handoff_unregister(struct notifier_block *n)
164{
165 return atomic_notifier_chain_unregister(&task_free_notifier, n);
166}
167EXPORT_SYMBOL_GPL(task_handoff_unregister);
168
169int profile_event_register(enum profile_type type, struct notifier_block *n)
170{
171 int err = -EINVAL;
172
173 switch (type) {
174 case PROFILE_TASK_EXIT:
175 err = blocking_notifier_chain_register(
176 &task_exit_notifier, n);
177 break;
178 case PROFILE_MUNMAP:
179 err = blocking_notifier_chain_register(
180 &munmap_notifier, n);
181 break;
182 }
183
184 return err;
185}
186EXPORT_SYMBOL_GPL(profile_event_register);
187
188int profile_event_unregister(enum profile_type type, struct notifier_block *n)
189{
190 int err = -EINVAL;
191
192 switch (type) {
193 case PROFILE_TASK_EXIT:
194 err = blocking_notifier_chain_unregister(
195 &task_exit_notifier, n);
196 break;
197 case PROFILE_MUNMAP:
198 err = blocking_notifier_chain_unregister(
199 &munmap_notifier, n);
200 break;
201 }
202
203 return err;
204}
205EXPORT_SYMBOL_GPL(profile_event_unregister);
206
207#if defined(CONFIG_SMP) && defined(CONFIG_PROC_FS)
208/*
209 * Each cpu has a pair of open-addressed hashtables for pending
210 * profile hits. read_profile() IPI's all cpus to request them
211 * to flip buffers and flushes their contents to prof_buffer itself.
212 * Flip requests are serialized by the profile_flip_mutex. The sole
213 * use of having a second hashtable is for avoiding cacheline
214 * contention that would otherwise happen during flushes of pending
215 * profile hits required for the accuracy of reported profile hits
216 * and so resurrect the interrupt livelock issue.
217 *
218 * The open-addressed hashtables are indexed by profile buffer slot
219 * and hold the number of pending hits to that profile buffer slot on
220 * a cpu in an entry. When the hashtable overflows, all pending hits
221 * are accounted to their corresponding profile buffer slots with
222 * atomic_add() and the hashtable emptied. As numerous pending hits
223 * may be accounted to a profile buffer slot in a hashtable entry,
224 * this amortizes a number of atomic profile buffer increments likely
225 * to be far larger than the number of entries in the hashtable,
226 * particularly given that the number of distinct profile buffer
227 * positions to which hits are accounted during short intervals (e.g.
228 * several seconds) is usually very small. Exclusion from buffer
229 * flipping is provided by interrupt disablement (note that for
230 * SCHED_PROFILING or SLEEP_PROFILING profile_hit() may be called from
231 * process context).
232 * The hash function is meant to be lightweight as opposed to strong,
233 * and was vaguely inspired by ppc64 firmware-supported inverted
234 * pagetable hash functions, but uses a full hashtable full of finite
235 * collision chains, not just pairs of them.
236 *
237 * -- nyc
238 */
239static void __profile_flip_buffers(void *unused)
240{
241 int cpu = smp_processor_id();
242
243 per_cpu(cpu_profile_flip, cpu) = !per_cpu(cpu_profile_flip, cpu);
244}
245
246static void profile_flip_buffers(void)
247{
248 int i, j, cpu;
249
250 mutex_lock(&profile_flip_mutex);
251 j = per_cpu(cpu_profile_flip, get_cpu());
252 put_cpu();
253 on_each_cpu(__profile_flip_buffers, NULL, 1);
254 for_each_online_cpu(cpu) {
255 struct profile_hit *hits = per_cpu(cpu_profile_hits, cpu)[j];
256 for (i = 0; i < NR_PROFILE_HIT; ++i) {
257 if (!hits[i].hits) {
258 if (hits[i].pc)
259 hits[i].pc = 0;
260 continue;
261 }
262 atomic_add(hits[i].hits, &prof_buffer[hits[i].pc]);
263 hits[i].hits = hits[i].pc = 0;
264 }
265 }
266 mutex_unlock(&profile_flip_mutex);
267}
268
269static void profile_discard_flip_buffers(void)
270{
271 int i, cpu;
272
273 mutex_lock(&profile_flip_mutex);
274 i = per_cpu(cpu_profile_flip, get_cpu());
275 put_cpu();
276 on_each_cpu(__profile_flip_buffers, NULL, 1);
277 for_each_online_cpu(cpu) {
278 struct profile_hit *hits = per_cpu(cpu_profile_hits, cpu)[i];
279 memset(hits, 0, NR_PROFILE_HIT*sizeof(struct profile_hit));
280 }
281 mutex_unlock(&profile_flip_mutex);
282}
283
284static void do_profile_hits(int type, void *__pc, unsigned int nr_hits)
285{
286 unsigned long primary, secondary, flags, pc = (unsigned long)__pc;
287 int i, j, cpu;
288 struct profile_hit *hits;
289
290 pc = min((pc - (unsigned long)_stext) >> prof_shift, prof_len - 1);
291 i = primary = (pc & (NR_PROFILE_GRP - 1)) << PROFILE_GRPSHIFT;
292 secondary = (~(pc << 1) & (NR_PROFILE_GRP - 1)) << PROFILE_GRPSHIFT;
293 cpu = get_cpu();
294 hits = per_cpu(cpu_profile_hits, cpu)[per_cpu(cpu_profile_flip, cpu)];
295 if (!hits) {
296 put_cpu();
297 return;
298 }
299 /*
300 * We buffer the global profiler buffer into a per-CPU
301 * queue and thus reduce the number of global (and possibly
302 * NUMA-alien) accesses. The write-queue is self-coalescing:
303 */
304 local_irq_save(flags);
305 do {
306 for (j = 0; j < PROFILE_GRPSZ; ++j) {
307 if (hits[i + j].pc == pc) {
308 hits[i + j].hits += nr_hits;
309 goto out;
310 } else if (!hits[i + j].hits) {
311 hits[i + j].pc = pc;
312 hits[i + j].hits = nr_hits;
313 goto out;
314 }
315 }
316 i = (i + secondary) & (NR_PROFILE_HIT - 1);
317 } while (i != primary);
318
319 /*
320 * Add the current hit(s) and flush the write-queue out
321 * to the global buffer:
322 */
323 atomic_add(nr_hits, &prof_buffer[pc]);
324 for (i = 0; i < NR_PROFILE_HIT; ++i) {
325 atomic_add(hits[i].hits, &prof_buffer[hits[i].pc]);
326 hits[i].pc = hits[i].hits = 0;
327 }
328out:
329 local_irq_restore(flags);
330 put_cpu();
331}
332
333static int profile_dead_cpu(unsigned int cpu)
334{
335 struct page *page;
336 int i;
337
338 if (prof_cpu_mask != NULL)
339 cpumask_clear_cpu(cpu, prof_cpu_mask);
340
341 for (i = 0; i < 2; i++) {
342 if (per_cpu(cpu_profile_hits, cpu)[i]) {
343 page = virt_to_page(per_cpu(cpu_profile_hits, cpu)[i]);
344 per_cpu(cpu_profile_hits, cpu)[i] = NULL;
345 __free_page(page);
346 }
347 }
348 return 0;
349}
350
351static int profile_prepare_cpu(unsigned int cpu)
352{
353 int i, node = cpu_to_mem(cpu);
354 struct page *page;
355
356 per_cpu(cpu_profile_flip, cpu) = 0;
357
358 for (i = 0; i < 2; i++) {
359 if (per_cpu(cpu_profile_hits, cpu)[i])
360 continue;
361
362 page = __alloc_pages_node(node, GFP_KERNEL | __GFP_ZERO, 0);
363 if (!page) {
364 profile_dead_cpu(cpu);
365 return -ENOMEM;
366 }
367 per_cpu(cpu_profile_hits, cpu)[i] = page_address(page);
368
369 }
370 return 0;
371}
372
373static int profile_online_cpu(unsigned int cpu)
374{
375 if (prof_cpu_mask != NULL)
376 cpumask_set_cpu(cpu, prof_cpu_mask);
377
378 return 0;
379}
380
381#else /* !CONFIG_SMP */
382#define profile_flip_buffers() do { } while (0)
383#define profile_discard_flip_buffers() do { } while (0)
384
385static void do_profile_hits(int type, void *__pc, unsigned int nr_hits)
386{
387 unsigned long pc;
388 pc = ((unsigned long)__pc - (unsigned long)_stext) >> prof_shift;
389 atomic_add(nr_hits, &prof_buffer[min(pc, prof_len - 1)]);
390}
391#endif /* !CONFIG_SMP */
392
393void profile_hits(int type, void *__pc, unsigned int nr_hits)
394{
395 if (prof_on != type || !prof_buffer)
396 return;
397 do_profile_hits(type, __pc, nr_hits);
398}
399EXPORT_SYMBOL_GPL(profile_hits);
400
401void profile_tick(int type)
402{
403 struct pt_regs *regs = get_irq_regs();
404
405 if (!user_mode(regs) && prof_cpu_mask != NULL &&
406 cpumask_test_cpu(smp_processor_id(), prof_cpu_mask))
407 profile_hit(type, (void *)profile_pc(regs));
408}
409
410#ifdef CONFIG_PROC_FS
411#include <linux/proc_fs.h>
412#include <linux/seq_file.h>
413#include <linux/uaccess.h>
414
415static int prof_cpu_mask_proc_show(struct seq_file *m, void *v)
416{
417 seq_printf(m, "%*pb\n", cpumask_pr_args(prof_cpu_mask));
418 return 0;
419}
420
421static int prof_cpu_mask_proc_open(struct inode *inode, struct file *file)
422{
423 return single_open(file, prof_cpu_mask_proc_show, NULL);
424}
425
426static ssize_t prof_cpu_mask_proc_write(struct file *file,
427 const char __user *buffer, size_t count, loff_t *pos)
428{
429 cpumask_var_t new_value;
430 int err;
431
432 if (!alloc_cpumask_var(&new_value, GFP_KERNEL))
433 return -ENOMEM;
434
435 err = cpumask_parse_user(buffer, count, new_value);
436 if (!err) {
437 cpumask_copy(prof_cpu_mask, new_value);
438 err = count;
439 }
440 free_cpumask_var(new_value);
441 return err;
442}
443
444static const struct file_operations prof_cpu_mask_proc_fops = {
445 .open = prof_cpu_mask_proc_open,
446 .read = seq_read,
447 .llseek = seq_lseek,
448 .release = single_release,
449 .write = prof_cpu_mask_proc_write,
450};
451
452void create_prof_cpu_mask(void)
453{
454 /* create /proc/irq/prof_cpu_mask */
455 proc_create("irq/prof_cpu_mask", 0600, NULL, &prof_cpu_mask_proc_fops);
456}
457
458/*
459 * This function accesses profiling information. The returned data is
460 * binary: the sampling step and the actual contents of the profile
461 * buffer. Use of the program readprofile is recommended in order to
462 * get meaningful info out of these data.
463 */
464static ssize_t
465read_profile(struct file *file, char __user *buf, size_t count, loff_t *ppos)
466{
467 unsigned long p = *ppos;
468 ssize_t read;
469 char *pnt;
470 unsigned int sample_step = 1 << prof_shift;
471
472 profile_flip_buffers();
473 if (p >= (prof_len+1)*sizeof(unsigned int))
474 return 0;
475 if (count > (prof_len+1)*sizeof(unsigned int) - p)
476 count = (prof_len+1)*sizeof(unsigned int) - p;
477 read = 0;
478
479 while (p < sizeof(unsigned int) && count > 0) {
480 if (put_user(*((char *)(&sample_step)+p), buf))
481 return -EFAULT;
482 buf++; p++; count--; read++;
483 }
484 pnt = (char *)prof_buffer + p - sizeof(atomic_t);
485 if (copy_to_user(buf, (void *)pnt, count))
486 return -EFAULT;
487 read += count;
488 *ppos += read;
489 return read;
490}
491
492/*
493 * Writing to /proc/profile resets the counters
494 *
495 * Writing a 'profiling multiplier' value into it also re-sets the profiling
496 * interrupt frequency, on architectures that support this.
497 */
498static ssize_t write_profile(struct file *file, const char __user *buf,
499 size_t count, loff_t *ppos)
500{
501#ifdef CONFIG_SMP
502 extern int setup_profiling_timer(unsigned int multiplier);
503
504 if (count == sizeof(int)) {
505 unsigned int multiplier;
506
507 if (copy_from_user(&multiplier, buf, sizeof(int)))
508 return -EFAULT;
509
510 if (setup_profiling_timer(multiplier))
511 return -EINVAL;
512 }
513#endif
514 profile_discard_flip_buffers();
515 memset(prof_buffer, 0, prof_len * sizeof(atomic_t));
516 return count;
517}
518
519static const struct file_operations proc_profile_operations = {
520 .read = read_profile,
521 .write = write_profile,
522 .llseek = default_llseek,
523};
524
525int __ref create_proc_profile(void)
526{
527 struct proc_dir_entry *entry;
528#ifdef CONFIG_SMP
529 enum cpuhp_state online_state;
530#endif
531
532 int err = 0;
533
534 if (!prof_on)
535 return 0;
536#ifdef CONFIG_SMP
537 err = cpuhp_setup_state(CPUHP_PROFILE_PREPARE, "PROFILE_PREPARE",
538 profile_prepare_cpu, profile_dead_cpu);
539 if (err)
540 return err;
541
542 err = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "AP_PROFILE_ONLINE",
543 profile_online_cpu, NULL);
544 if (err < 0)
545 goto err_state_prep;
546 online_state = err;
547 err = 0;
548#endif
549 entry = proc_create("profile", S_IWUSR | S_IRUGO,
550 NULL, &proc_profile_operations);
551 if (!entry)
552 goto err_state_onl;
553 proc_set_size(entry, (1 + prof_len) * sizeof(atomic_t));
554
555 return err;
556err_state_onl:
557#ifdef CONFIG_SMP
558 cpuhp_remove_state(online_state);
559err_state_prep:
560 cpuhp_remove_state(CPUHP_PROFILE_PREPARE);
561#endif
562 return err;
563}
564subsys_initcall(create_proc_profile);
565#endif /* CONFIG_PROC_FS */