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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
20static struct lock_contention_bpf *skel;
21
22int 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 skel->rodata->has_cpu = 1;
51 ncpus = perf_cpu_map__nr(evlist->core.user_requested_cpus);
52 }
53 if (target__has_task(target)) {
54 skel->rodata->has_task = 1;
55 ntasks = perf_thread_map__nr(evlist->core.threads);
56 }
57 if (con->filters->nr_types) {
58 skel->rodata->has_type = 1;
59 ntypes = con->filters->nr_types;
60 }
61 if (con->filters->nr_cgrps) {
62 skel->rodata->has_cgroup = 1;
63 ncgrps = con->filters->nr_cgrps;
64 }
65
66 /* resolve lock name filters to addr */
67 if (con->filters->nr_syms) {
68 struct symbol *sym;
69 struct map *kmap;
70 unsigned long *addrs;
71
72 for (i = 0; i < con->filters->nr_syms; i++) {
73 sym = machine__find_kernel_symbol_by_name(con->machine,
74 con->filters->syms[i],
75 &kmap);
76 if (sym == NULL) {
77 pr_warning("ignore unknown symbol: %s\n",
78 con->filters->syms[i]);
79 continue;
80 }
81
82 addrs = realloc(con->filters->addrs,
83 (con->filters->nr_addrs + 1) * sizeof(*addrs));
84 if (addrs == NULL) {
85 pr_warning("memory allocation failure\n");
86 continue;
87 }
88
89 addrs[con->filters->nr_addrs++] = map__unmap_ip(kmap, sym->start);
90 con->filters->addrs = addrs;
91 }
92 naddrs = con->filters->nr_addrs;
93 skel->rodata->has_addr = 1;
94 }
95
96 bpf_map__set_max_entries(skel->maps.cpu_filter, ncpus);
97 bpf_map__set_max_entries(skel->maps.task_filter, ntasks);
98 bpf_map__set_max_entries(skel->maps.type_filter, ntypes);
99 bpf_map__set_max_entries(skel->maps.addr_filter, naddrs);
100 bpf_map__set_max_entries(skel->maps.cgroup_filter, ncgrps);
101
102 skel->rodata->stack_skip = con->stack_skip;
103 skel->rodata->aggr_mode = con->aggr_mode;
104 skel->rodata->needs_callstack = con->save_callstack;
105 skel->rodata->lock_owner = con->owner;
106
107 if (con->aggr_mode == LOCK_AGGR_CGROUP || con->filters->nr_cgrps) {
108 if (cgroup_is_v2("perf_event"))
109 skel->rodata->use_cgroup_v2 = 1;
110 }
111
112 if (lock_contention_bpf__load(skel) < 0) {
113 pr_err("Failed to load lock-contention BPF skeleton\n");
114 return -1;
115 }
116
117 if (target__has_cpu(target)) {
118 u32 cpu;
119 u8 val = 1;
120
121 fd = bpf_map__fd(skel->maps.cpu_filter);
122
123 for (i = 0; i < ncpus; i++) {
124 cpu = perf_cpu_map__cpu(evlist->core.user_requested_cpus, i).cpu;
125 bpf_map_update_elem(fd, &cpu, &val, BPF_ANY);
126 }
127 }
128
129 if (target__has_task(target)) {
130 u32 pid;
131 u8 val = 1;
132
133 fd = bpf_map__fd(skel->maps.task_filter);
134
135 for (i = 0; i < ntasks; i++) {
136 pid = perf_thread_map__pid(evlist->core.threads, i);
137 bpf_map_update_elem(fd, &pid, &val, BPF_ANY);
138 }
139 }
140
141 if (target__none(target) && evlist->workload.pid > 0) {
142 u32 pid = evlist->workload.pid;
143 u8 val = 1;
144
145 fd = bpf_map__fd(skel->maps.task_filter);
146 bpf_map_update_elem(fd, &pid, &val, BPF_ANY);
147 }
148
149 if (con->filters->nr_types) {
150 u8 val = 1;
151
152 fd = bpf_map__fd(skel->maps.type_filter);
153
154 for (i = 0; i < con->filters->nr_types; i++)
155 bpf_map_update_elem(fd, &con->filters->types[i], &val, BPF_ANY);
156 }
157
158 if (con->filters->nr_addrs) {
159 u8 val = 1;
160
161 fd = bpf_map__fd(skel->maps.addr_filter);
162
163 for (i = 0; i < con->filters->nr_addrs; i++)
164 bpf_map_update_elem(fd, &con->filters->addrs[i], &val, BPF_ANY);
165 }
166
167 if (con->filters->nr_cgrps) {
168 u8 val = 1;
169
170 fd = bpf_map__fd(skel->maps.cgroup_filter);
171
172 for (i = 0; i < con->filters->nr_cgrps; i++)
173 bpf_map_update_elem(fd, &con->filters->cgrps[i], &val, BPF_ANY);
174 }
175
176 if (con->aggr_mode == LOCK_AGGR_CGROUP)
177 read_all_cgroups(&con->cgroups);
178
179 bpf_program__set_autoload(skel->progs.collect_lock_syms, false);
180
181 lock_contention_bpf__attach(skel);
182 return 0;
183}
184
185/*
186 * Run the BPF program directly using BPF_PROG_TEST_RUN to update the end
187 * timestamp in ktime so that it can calculate delta easily.
188 */
189static void mark_end_timestamp(void)
190{
191 DECLARE_LIBBPF_OPTS(bpf_test_run_opts, opts,
192 .flags = BPF_F_TEST_RUN_ON_CPU,
193 );
194 int prog_fd = bpf_program__fd(skel->progs.end_timestamp);
195
196 bpf_prog_test_run_opts(prog_fd, &opts);
197}
198
199static void update_lock_stat(int map_fd, int pid, u64 end_ts,
200 enum lock_aggr_mode aggr_mode,
201 struct tstamp_data *ts_data)
202{
203 u64 delta;
204 struct contention_key stat_key = {};
205 struct contention_data stat_data;
206
207 if (ts_data->timestamp >= end_ts)
208 return;
209
210 delta = end_ts - ts_data->timestamp;
211
212 switch (aggr_mode) {
213 case LOCK_AGGR_CALLER:
214 stat_key.stack_id = ts_data->stack_id;
215 break;
216 case LOCK_AGGR_TASK:
217 stat_key.pid = pid;
218 break;
219 case LOCK_AGGR_ADDR:
220 stat_key.lock_addr_or_cgroup = ts_data->lock;
221 break;
222 case LOCK_AGGR_CGROUP:
223 /* TODO */
224 return;
225 default:
226 return;
227 }
228
229 if (bpf_map_lookup_elem(map_fd, &stat_key, &stat_data) < 0)
230 return;
231
232 stat_data.total_time += delta;
233 stat_data.count++;
234
235 if (delta > stat_data.max_time)
236 stat_data.max_time = delta;
237 if (delta < stat_data.min_time)
238 stat_data.min_time = delta;
239
240 bpf_map_update_elem(map_fd, &stat_key, &stat_data, BPF_EXIST);
241}
242
243/*
244 * Account entries in the tstamp map (which didn't see the corresponding
245 * lock:contention_end tracepoint) using end_ts.
246 */
247static void account_end_timestamp(struct lock_contention *con)
248{
249 int ts_fd, stat_fd;
250 int *prev_key, key;
251 u64 end_ts = skel->bss->end_ts;
252 int total_cpus;
253 enum lock_aggr_mode aggr_mode = con->aggr_mode;
254 struct tstamp_data ts_data, *cpu_data;
255
256 /* Iterate per-task tstamp map (key = TID) */
257 ts_fd = bpf_map__fd(skel->maps.tstamp);
258 stat_fd = bpf_map__fd(skel->maps.lock_stat);
259
260 prev_key = NULL;
261 while (!bpf_map_get_next_key(ts_fd, prev_key, &key)) {
262 if (bpf_map_lookup_elem(ts_fd, &key, &ts_data) == 0) {
263 int pid = key;
264
265 if (aggr_mode == LOCK_AGGR_TASK && con->owner)
266 pid = ts_data.flags;
267
268 update_lock_stat(stat_fd, pid, end_ts, aggr_mode,
269 &ts_data);
270 }
271
272 prev_key = &key;
273 }
274
275 /* Now it'll check per-cpu tstamp map which doesn't have TID. */
276 if (aggr_mode == LOCK_AGGR_TASK || aggr_mode == LOCK_AGGR_CGROUP)
277 return;
278
279 total_cpus = cpu__max_cpu().cpu;
280 ts_fd = bpf_map__fd(skel->maps.tstamp_cpu);
281
282 cpu_data = calloc(total_cpus, sizeof(*cpu_data));
283 if (cpu_data == NULL)
284 return;
285
286 prev_key = NULL;
287 while (!bpf_map_get_next_key(ts_fd, prev_key, &key)) {
288 if (bpf_map_lookup_elem(ts_fd, &key, cpu_data) < 0)
289 goto next;
290
291 for (int i = 0; i < total_cpus; i++) {
292 if (cpu_data[i].lock == 0)
293 continue;
294
295 update_lock_stat(stat_fd, -1, end_ts, aggr_mode,
296 &cpu_data[i]);
297 }
298
299next:
300 prev_key = &key;
301 }
302 free(cpu_data);
303}
304
305int lock_contention_start(void)
306{
307 skel->bss->enabled = 1;
308 return 0;
309}
310
311int lock_contention_stop(void)
312{
313 skel->bss->enabled = 0;
314 mark_end_timestamp();
315 return 0;
316}
317
318static const char *lock_contention_get_name(struct lock_contention *con,
319 struct contention_key *key,
320 u64 *stack_trace, u32 flags)
321{
322 int idx = 0;
323 u64 addr;
324 const char *name = "";
325 static char name_buf[KSYM_NAME_LEN];
326 struct symbol *sym;
327 struct map *kmap;
328 struct machine *machine = con->machine;
329
330 if (con->aggr_mode == LOCK_AGGR_TASK) {
331 struct contention_task_data task;
332 int pid = key->pid;
333 int task_fd = bpf_map__fd(skel->maps.task_data);
334
335 /* do not update idle comm which contains CPU number */
336 if (pid) {
337 struct thread *t = machine__findnew_thread(machine, /*pid=*/-1, pid);
338
339 if (t == NULL)
340 return name;
341 if (!bpf_map_lookup_elem(task_fd, &pid, &task) &&
342 thread__set_comm(t, task.comm, /*timestamp=*/0))
343 name = task.comm;
344 }
345 return name;
346 }
347
348 if (con->aggr_mode == LOCK_AGGR_ADDR) {
349 int lock_fd = bpf_map__fd(skel->maps.lock_syms);
350
351 /* per-process locks set upper bits of the flags */
352 if (flags & LCD_F_MMAP_LOCK)
353 return "mmap_lock";
354 if (flags & LCD_F_SIGHAND_LOCK)
355 return "siglock";
356
357 /* global locks with symbols */
358 sym = machine__find_kernel_symbol(machine, key->lock_addr_or_cgroup, &kmap);
359 if (sym)
360 return sym->name;
361
362 /* try semi-global locks collected separately */
363 if (!bpf_map_lookup_elem(lock_fd, &key->lock_addr_or_cgroup, &flags)) {
364 if (flags == LOCK_CLASS_RQLOCK)
365 return "rq_lock";
366 }
367
368 return "";
369 }
370
371 if (con->aggr_mode == LOCK_AGGR_CGROUP) {
372 u64 cgrp_id = key->lock_addr_or_cgroup;
373 struct cgroup *cgrp = __cgroup__find(&con->cgroups, cgrp_id);
374
375 if (cgrp)
376 return cgrp->name;
377
378 snprintf(name_buf, sizeof(name_buf), "cgroup:%" PRIu64 "", cgrp_id);
379 return name_buf;
380 }
381
382 /* LOCK_AGGR_CALLER: skip lock internal functions */
383 while (machine__is_lock_function(machine, stack_trace[idx]) &&
384 idx < con->max_stack - 1)
385 idx++;
386
387 addr = stack_trace[idx];
388 sym = machine__find_kernel_symbol(machine, addr, &kmap);
389
390 if (sym) {
391 unsigned long offset;
392
393 offset = map__map_ip(kmap, addr) - sym->start;
394
395 if (offset == 0)
396 return sym->name;
397
398 snprintf(name_buf, sizeof(name_buf), "%s+%#lx", sym->name, offset);
399 } else {
400 snprintf(name_buf, sizeof(name_buf), "%#lx", (unsigned long)addr);
401 }
402
403 return name_buf;
404}
405
406int lock_contention_read(struct lock_contention *con)
407{
408 int fd, stack, err = 0;
409 struct contention_key *prev_key, key = {};
410 struct contention_data data = {};
411 struct lock_stat *st = NULL;
412 struct machine *machine = con->machine;
413 u64 *stack_trace;
414 size_t stack_size = con->max_stack * sizeof(*stack_trace);
415
416 fd = bpf_map__fd(skel->maps.lock_stat);
417 stack = bpf_map__fd(skel->maps.stacks);
418
419 con->fails.task = skel->bss->task_fail;
420 con->fails.stack = skel->bss->stack_fail;
421 con->fails.time = skel->bss->time_fail;
422 con->fails.data = skel->bss->data_fail;
423
424 stack_trace = zalloc(stack_size);
425 if (stack_trace == NULL)
426 return -1;
427
428 account_end_timestamp(con);
429
430 if (con->aggr_mode == LOCK_AGGR_TASK) {
431 struct thread *idle = machine__findnew_thread(machine,
432 /*pid=*/0,
433 /*tid=*/0);
434 thread__set_comm(idle, "swapper", /*timestamp=*/0);
435 }
436
437 if (con->aggr_mode == LOCK_AGGR_ADDR) {
438 DECLARE_LIBBPF_OPTS(bpf_test_run_opts, opts,
439 .flags = BPF_F_TEST_RUN_ON_CPU,
440 );
441 int prog_fd = bpf_program__fd(skel->progs.collect_lock_syms);
442
443 bpf_prog_test_run_opts(prog_fd, &opts);
444 }
445
446 /* make sure it loads the kernel map */
447 maps__load_first(machine->kmaps);
448
449 prev_key = NULL;
450 while (!bpf_map_get_next_key(fd, prev_key, &key)) {
451 s64 ls_key;
452 const char *name;
453
454 /* to handle errors in the loop body */
455 err = -1;
456
457 bpf_map_lookup_elem(fd, &key, &data);
458 if (con->save_callstack) {
459 bpf_map_lookup_elem(stack, &key.stack_id, stack_trace);
460
461 if (!match_callstack_filter(machine, stack_trace)) {
462 con->nr_filtered += data.count;
463 goto next;
464 }
465 }
466
467 switch (con->aggr_mode) {
468 case LOCK_AGGR_CALLER:
469 ls_key = key.stack_id;
470 break;
471 case LOCK_AGGR_TASK:
472 ls_key = key.pid;
473 break;
474 case LOCK_AGGR_ADDR:
475 case LOCK_AGGR_CGROUP:
476 ls_key = key.lock_addr_or_cgroup;
477 break;
478 default:
479 goto next;
480 }
481
482 st = lock_stat_find(ls_key);
483 if (st != NULL) {
484 st->wait_time_total += data.total_time;
485 if (st->wait_time_max < data.max_time)
486 st->wait_time_max = data.max_time;
487 if (st->wait_time_min > data.min_time)
488 st->wait_time_min = data.min_time;
489
490 st->nr_contended += data.count;
491 if (st->nr_contended)
492 st->avg_wait_time = st->wait_time_total / st->nr_contended;
493 goto next;
494 }
495
496 name = lock_contention_get_name(con, &key, stack_trace, data.flags);
497 st = lock_stat_findnew(ls_key, name, data.flags);
498 if (st == NULL)
499 break;
500
501 st->nr_contended = data.count;
502 st->wait_time_total = data.total_time;
503 st->wait_time_max = data.max_time;
504 st->wait_time_min = data.min_time;
505
506 if (data.count)
507 st->avg_wait_time = data.total_time / data.count;
508
509 if (con->aggr_mode == LOCK_AGGR_CALLER && verbose > 0) {
510 st->callstack = memdup(stack_trace, stack_size);
511 if (st->callstack == NULL)
512 break;
513 }
514
515next:
516 prev_key = &key;
517
518 /* we're fine now, reset the error */
519 err = 0;
520 }
521
522 free(stack_trace);
523
524 return err;
525}
526
527int lock_contention_finish(struct lock_contention *con)
528{
529 if (skel) {
530 skel->bss->enabled = 0;
531 lock_contention_bpf__destroy(skel);
532 }
533
534 while (!RB_EMPTY_ROOT(&con->cgroups)) {
535 struct rb_node *node = rb_first(&con->cgroups);
536 struct cgroup *cgrp = rb_entry(node, struct cgroup, node);
537
538 rb_erase(node, &con->cgroups);
539 cgroup__put(cgrp);
540 }
541
542 return 0;
543}