1 // SPDX-License-Identifier: GPL-2.0
2 #include "util/cgroup.h"
3 #include "util/debug.h"
4 #include "util/evlist.h"
5 #include "util/machine.h"
6 #include "util/map.h"
7 #include "util/symbol.h"
8 #include "util/target.h"
9 #include "util/thread.h"
10 #include "util/thread_map.h"
11 #include "util/lock-contention.h"
12 #include <linux/zalloc.h>
13 #include <linux/string.h>
14 #include <bpf/bpf.h>
15 #include <inttypes.h>
16
17 #include "bpf_skel/lock_contention.skel.h"
18 #include "bpf_skel/lock_data.h"
19
20 static struct lock_contention_bpf *skel;
21
22 int lock_contention_prepare(struct lock_contention *con)
23 {
24 int i, fd;
25 int ncpus = 1, ntasks = 1, ntypes = 1, naddrs = 1, ncgrps = 1;
26 struct evlist *evlist = con->evlist;
27 struct target *target = con->target;
28
29 skel = lock_contention_bpf__open();
30 if (!skel) {
31 pr_err("Failed to open lock-contention BPF skeleton\n");
32 return -1;
33 }
34
35 bpf_map__set_value_size(skel->maps.stacks, con->max_stack * sizeof(u64));
36 bpf_map__set_max_entries(skel->maps.lock_stat, con->map_nr_entries);
37 bpf_map__set_max_entries(skel->maps.tstamp, con->map_nr_entries);
38
39 if (con->aggr_mode == LOCK_AGGR_TASK)
40 bpf_map__set_max_entries(skel->maps.task_data, con->map_nr_entries);
41 else
42 bpf_map__set_max_entries(skel->maps.task_data, 1);
43
44 if (con->save_callstack)
45 bpf_map__set_max_entries(skel->maps.stacks, con->map_nr_entries);
46 else
47 bpf_map__set_max_entries(skel->maps.stacks, 1);
48
49 if (target__has_cpu(target))
50 ncpus = perf_cpu_map__nr(evlist->core.user_requested_cpus);
51 if (target__has_task(target))
52 ntasks = perf_thread_map__nr(evlist->core.threads);
53 if (con->filters->nr_types)
54 ntypes = con->filters->nr_types;
55 if (con->filters->nr_cgrps)
56 ncgrps = con->filters->nr_cgrps;
57
58 /* resolve lock name filters to addr */
59 if (con->filters->nr_syms) {
60 struct symbol *sym;
61 struct map *kmap;
62 unsigned long *addrs;
63
64 for (i = 0; i < con->filters->nr_syms; i++) {
65 sym = machine__find_kernel_symbol_by_name(con->machine,
66 con->filters->syms[i],
67 &kmap);
68 if (sym == NULL) {
69 pr_warning("ignore unknown symbol: %s\n",
70 con->filters->syms[i]);
71 continue;
72 }
73
74 addrs = realloc(con->filters->addrs,
75 (con->filters->nr_addrs + 1) * sizeof(*addrs));
76 if (addrs == NULL) {
77 pr_warning("memory allocation failure\n");
78 continue;
79 }
80
81 addrs[con->filters->nr_addrs++] = map__unmap_ip(kmap, sym->start);
82 con->filters->addrs = addrs;
83 }
84 naddrs = con->filters->nr_addrs;
85 }
86
87 bpf_map__set_max_entries(skel->maps.cpu_filter, ncpus);
88 bpf_map__set_max_entries(skel->maps.task_filter, ntasks);
89 bpf_map__set_max_entries(skel->maps.type_filter, ntypes);
90 bpf_map__set_max_entries(skel->maps.addr_filter, naddrs);
91 bpf_map__set_max_entries(skel->maps.cgroup_filter, ncgrps);
92
93 if (lock_contention_bpf__load(skel) < 0) {
94 pr_err("Failed to load lock-contention BPF skeleton\n");
95 return -1;
96 }
97
98 if (target__has_cpu(target)) {
99 u32 cpu;
100 u8 val = 1;
101
102 skel->bss->has_cpu = 1;
103 fd = bpf_map__fd(skel->maps.cpu_filter);
104
105 for (i = 0; i < ncpus; i++) {
106 cpu = perf_cpu_map__cpu(evlist->core.user_requested_cpus, i).cpu;
107 bpf_map_update_elem(fd, &cpu, &val, BPF_ANY);
108 }
109 }
110
111 if (target__has_task(target)) {
112 u32 pid;
113 u8 val = 1;
114
115 skel->bss->has_task = 1;
116 fd = bpf_map__fd(skel->maps.task_filter);
117
118 for (i = 0; i < ntasks; i++) {
119 pid = perf_thread_map__pid(evlist->core.threads, i);
120 bpf_map_update_elem(fd, &pid, &val, BPF_ANY);
121 }
122 }
123
124 if (target__none(target) && evlist->workload.pid > 0) {
125 u32 pid = evlist->workload.pid;
126 u8 val = 1;
127
128 skel->bss->has_task = 1;
129 fd = bpf_map__fd(skel->maps.task_filter);
130 bpf_map_update_elem(fd, &pid, &val, BPF_ANY);
131 }
132
133 if (con->filters->nr_types) {
134 u8 val = 1;
135
136 skel->bss->has_type = 1;
137 fd = bpf_map__fd(skel->maps.type_filter);
138
139 for (i = 0; i < con->filters->nr_types; i++)
140 bpf_map_update_elem(fd, &con->filters->types[i], &val, BPF_ANY);
141 }
142
143 if (con->filters->nr_addrs) {
144 u8 val = 1;
145
146 skel->bss->has_addr = 1;
147 fd = bpf_map__fd(skel->maps.addr_filter);
148
149 for (i = 0; i < con->filters->nr_addrs; i++)
150 bpf_map_update_elem(fd, &con->filters->addrs[i], &val, BPF_ANY);
151 }
152
153 if (con->filters->nr_cgrps) {
154 u8 val = 1;
155
156 skel->bss->has_cgroup = 1;
157 fd = bpf_map__fd(skel->maps.cgroup_filter);
158
159 for (i = 0; i < con->filters->nr_cgrps; i++)
160 bpf_map_update_elem(fd, &con->filters->cgrps[i], &val, BPF_ANY);
161 }
162
163 /* these don't work well if in the rodata section */
164 skel->bss->stack_skip = con->stack_skip;
165 skel->bss->aggr_mode = con->aggr_mode;
166 skel->bss->needs_callstack = con->save_callstack;
167 skel->bss->lock_owner = con->owner;
168
169 if (con->aggr_mode == LOCK_AGGR_CGROUP) {
170 if (cgroup_is_v2("perf_event"))
171 skel->bss->use_cgroup_v2 = 1;
172
173 read_all_cgroups(&con->cgroups);
174 }
175
176 bpf_program__set_autoload(skel->progs.collect_lock_syms, false);
177
178 lock_contention_bpf__attach(skel);
179 return 0;
180 }
181
182 /*
183 * Run the BPF program directly using BPF_PROG_TEST_RUN to update the end
184 * timestamp in ktime so that it can calculate delta easily.
185 */
186 static void mark_end_timestamp(void)
187 {
188 DECLARE_LIBBPF_OPTS(bpf_test_run_opts, opts,
189 .flags = BPF_F_TEST_RUN_ON_CPU,
190 );
191 int prog_fd = bpf_program__fd(skel->progs.end_timestamp);
192
193 bpf_prog_test_run_opts(prog_fd, &opts);
194 }
195
196 static void update_lock_stat(int map_fd, int pid, u64 end_ts,
197 enum lock_aggr_mode aggr_mode,
198 struct tstamp_data *ts_data)
199 {
200 u64 delta;
201 struct contention_key stat_key = {};
202 struct contention_data stat_data;
203
204 if (ts_data->timestamp >= end_ts)
205 return;
206
207 delta = end_ts - ts_data->timestamp;
208
209 switch (aggr_mode) {
210 case LOCK_AGGR_CALLER:
211 stat_key.stack_id = ts_data->stack_id;
212 break;
213 case LOCK_AGGR_TASK:
214 stat_key.pid = pid;
215 break;
216 case LOCK_AGGR_ADDR:
217 stat_key.lock_addr_or_cgroup = ts_data->lock;
218 break;
219 case LOCK_AGGR_CGROUP:
220 /* TODO */
221 return;
222 default:
223 return;
224 }
225
226 if (bpf_map_lookup_elem(map_fd, &stat_key, &stat_data) < 0)
227 return;
228
229 stat_data.total_time += delta;
230 stat_data.count++;
231
232 if (delta > stat_data.max_time)
233 stat_data.max_time = delta;
234 if (delta < stat_data.min_time)
235 stat_data.min_time = delta;
236
237 bpf_map_update_elem(map_fd, &stat_key, &stat_data, BPF_EXIST);
238 }
239
240 /*
241 * Account entries in the tstamp map (which didn't see the corresponding
242 * lock:contention_end tracepoint) using end_ts.
243 */
244 static void account_end_timestamp(struct lock_contention *con)
245 {
246 int ts_fd, stat_fd;
247 int *prev_key, key;
248 u64 end_ts = skel->bss->end_ts;
249 int total_cpus;
250 enum lock_aggr_mode aggr_mode = con->aggr_mode;
251 struct tstamp_data ts_data, *cpu_data;
252
253 /* Iterate per-task tstamp map (key = TID) */
254 ts_fd = bpf_map__fd(skel->maps.tstamp);
255 stat_fd = bpf_map__fd(skel->maps.lock_stat);
256
257 prev_key = NULL;
258 while (!bpf_map_get_next_key(ts_fd, prev_key, &key)) {
259 if (bpf_map_lookup_elem(ts_fd, &key, &ts_data) == 0) {
260 int pid = key;
261
262 if (aggr_mode == LOCK_AGGR_TASK && con->owner)
263 pid = ts_data.flags;
264
265 update_lock_stat(stat_fd, pid, end_ts, aggr_mode,
266 &ts_data);
267 }
268
269 prev_key = &key;
270 }
271
272 /* Now it'll check per-cpu tstamp map which doesn't have TID. */
273 if (aggr_mode == LOCK_AGGR_TASK || aggr_mode == LOCK_AGGR_CGROUP)
274 return;
275
276 total_cpus = cpu__max_cpu().cpu;
277 ts_fd = bpf_map__fd(skel->maps.tstamp_cpu);
278
279 cpu_data = calloc(total_cpus, sizeof(*cpu_data));
280 if (cpu_data == NULL)
281 return;
282
283 prev_key = NULL;
284 while (!bpf_map_get_next_key(ts_fd, prev_key, &key)) {
285 if (bpf_map_lookup_elem(ts_fd, &key, cpu_data) < 0)
286 goto next;
287
288 for (int i = 0; i < total_cpus; i++) {
289 if (cpu_data[i].lock == 0)
290 continue;
291
292 update_lock_stat(stat_fd, -1, end_ts, aggr_mode,
293 &cpu_data[i]);
294 }
295
296 next:
297 prev_key = &key;
298 }
299 free(cpu_data);
300 }
301
302 int lock_contention_start(void)
303 {
304 skel->bss->enabled = 1;
305 return 0;
306 }
307
308 int lock_contention_stop(void)
309 {
310 skel->bss->enabled = 0;
311 mark_end_timestamp();
312 return 0;
313 }
314
315 static const char *lock_contention_get_name(struct lock_contention *con,
316 struct contention_key *key,
317 u64 *stack_trace, u32 flags)
318 {
319 int idx = 0;
320 u64 addr;
321 const char *name = "";
322 static char name_buf[KSYM_NAME_LEN];
323 struct symbol *sym;
324 struct map *kmap;
325 struct machine *machine = con->machine;
326
327 if (con->aggr_mode == LOCK_AGGR_TASK) {
328 struct contention_task_data task;
329 int pid = key->pid;
330 int task_fd = bpf_map__fd(skel->maps.task_data);
331
332 /* do not update idle comm which contains CPU number */
333 if (pid) {
334 struct thread *t = machine__findnew_thread(machine, /*pid=*/-1, pid);
335
336 if (t == NULL)
337 return name;
338 if (!bpf_map_lookup_elem(task_fd, &pid, &task) &&
339 thread__set_comm(t, task.comm, /*timestamp=*/0))
340 name = task.comm;
341 }
342 return name;
343 }
344
345 if (con->aggr_mode == LOCK_AGGR_ADDR) {
346 int lock_fd = bpf_map__fd(skel->maps.lock_syms);
347
348 /* per-process locks set upper bits of the flags */
349 if (flags & LCD_F_MMAP_LOCK)
350 return "mmap_lock";
351 if (flags & LCD_F_SIGHAND_LOCK)
352 return "siglock";
353
354 /* global locks with symbols */
355 sym = machine__find_kernel_symbol(machine, key->lock_addr_or_cgroup, &kmap);
356 if (sym)
357 return sym->name;
358
359 /* try semi-global locks collected separately */
360 if (!bpf_map_lookup_elem(lock_fd, &key->lock_addr_or_cgroup, &flags)) {
361 if (flags == LOCK_CLASS_RQLOCK)
362 return "rq_lock";
363 }
364
365 return "";
366 }
367
368 if (con->aggr_mode == LOCK_AGGR_CGROUP) {
369 u64 cgrp_id = key->lock_addr_or_cgroup;
370 struct cgroup *cgrp = __cgroup__find(&con->cgroups, cgrp_id);
371
372 if (cgrp)
373 return cgrp->name;
374
375 snprintf(name_buf, sizeof(name_buf), "cgroup:%" PRIu64 "", cgrp_id);
376 return name_buf;
377 }
378
379 /* LOCK_AGGR_CALLER: skip lock internal functions */
380 while (machine__is_lock_function(machine, stack_trace[idx]) &&
381 idx < con->max_stack - 1)
382 idx++;
383
384 addr = stack_trace[idx];
385 sym = machine__find_kernel_symbol(machine, addr, &kmap);
386
387 if (sym) {
388 unsigned long offset;
389
390 offset = map__map_ip(kmap, addr) - sym->start;
391
392 if (offset == 0)
393 return sym->name;
394
395 snprintf(name_buf, sizeof(name_buf), "%s+%#lx", sym->name, offset);
396 } else {
397 snprintf(name_buf, sizeof(name_buf), "%#lx", (unsigned long)addr);
398 }
399
400 return name_buf;
401 }
402
403 int lock_contention_read(struct lock_contention *con)
404 {
405 int fd, stack, err = 0;
406 struct contention_key *prev_key, key = {};
407 struct contention_data data = {};
408 struct lock_stat *st = NULL;
409 struct machine *machine = con->machine;
410 u64 *stack_trace;
411 size_t stack_size = con->max_stack * sizeof(*stack_trace);
412
413 fd = bpf_map__fd(skel->maps.lock_stat);
414 stack = bpf_map__fd(skel->maps.stacks);
415
416 con->fails.task = skel->bss->task_fail;
417 con->fails.stack = skel->bss->stack_fail;
418 con->fails.time = skel->bss->time_fail;
419 con->fails.data = skel->bss->data_fail;
420
421 stack_trace = zalloc(stack_size);
422 if (stack_trace == NULL)
423 return -1;
424
425 account_end_timestamp(con);
426
427 if (con->aggr_mode == LOCK_AGGR_TASK) {
428 struct thread *idle = machine__findnew_thread(machine,
429 /*pid=*/0,
430 /*tid=*/0);
431 thread__set_comm(idle, "swapper", /*timestamp=*/0);
432 }
433
434 if (con->aggr_mode == LOCK_AGGR_ADDR) {
435 DECLARE_LIBBPF_OPTS(bpf_test_run_opts, opts,
436 .flags = BPF_F_TEST_RUN_ON_CPU,
437 );
438 int prog_fd = bpf_program__fd(skel->progs.collect_lock_syms);
439
440 bpf_prog_test_run_opts(prog_fd, &opts);
441 }
442
443 /* make sure it loads the kernel map */
444 maps__load_first(machine->kmaps);
445
446 prev_key = NULL;
447 while (!bpf_map_get_next_key(fd, prev_key, &key)) {
448 s64 ls_key;
449 const char *name;
450
451 /* to handle errors in the loop body */
452 err = -1;
453
454 bpf_map_lookup_elem(fd, &key, &data);
455 if (con->save_callstack) {
456 bpf_map_lookup_elem(stack, &key.stack_id, stack_trace);
457
458 if (!match_callstack_filter(machine, stack_trace)) {
459 con->nr_filtered += data.count;
460 goto next;
461 }
462 }
463
464 switch (con->aggr_mode) {
465 case LOCK_AGGR_CALLER:
466 ls_key = key.stack_id;
467 break;
468 case LOCK_AGGR_TASK:
469 ls_key = key.pid;
470 break;
471 case LOCK_AGGR_ADDR:
472 case LOCK_AGGR_CGROUP:
473 ls_key = key.lock_addr_or_cgroup;
474 break;
475 default:
476 goto next;
477 }
478
479 st = lock_stat_find(ls_key);
480 if (st != NULL) {
481 st->wait_time_total += data.total_time;
482 if (st->wait_time_max < data.max_time)
483 st->wait_time_max = data.max_time;
484 if (st->wait_time_min > data.min_time)
485 st->wait_time_min = data.min_time;
486
487 st->nr_contended += data.count;
488 if (st->nr_contended)
489 st->avg_wait_time = st->wait_time_total / st->nr_contended;
490 goto next;
491 }
492
493 name = lock_contention_get_name(con, &key, stack_trace, data.flags);
494 st = lock_stat_findnew(ls_key, name, data.flags);
495 if (st == NULL)
496 break;
497
498 st->nr_contended = data.count;
499 st->wait_time_total = data.total_time;
500 st->wait_time_max = data.max_time;
501 st->wait_time_min = data.min_time;
502
503 if (data.count)
504 st->avg_wait_time = data.total_time / data.count;
505
506 if (con->aggr_mode == LOCK_AGGR_CALLER && verbose > 0) {
507 st->callstack = memdup(stack_trace, stack_size);
508 if (st->callstack == NULL)
509 break;
510 }
511
512 next:
513 prev_key = &key;
514
515 /* we're fine now, reset the error */
516 err = 0;
517 }
518
519 free(stack_trace);
520
521 return err;
522 }
523
524 int lock_contention_finish(struct lock_contention *con)
525 {
526 if (skel) {
527 skel->bss->enabled = 0;
528 lock_contention_bpf__destroy(skel);
529 }
530
531 while (!RB_EMPTY_ROOT(&con->cgroups)) {
532 struct rb_node *node = rb_first(&con->cgroups);
533 struct cgroup *cgrp = rb_entry(node, struct cgroup, node);
534
535 rb_erase(node, &con->cgroups);
536 cgroup__put(cgrp);
537 }
538
539 return 0;
540 }
541
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