tools/perf/util/bpf_lock_contention.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 #include "util/debug.h"
   3 #include "util/evlist.h"
   4 #include "util/machine.h"
   5 #include "util/map.h"
   6 #include "util/symbol.h"
   7 #include "util/target.h"
   8 #include "util/thread.h"
   9 #include "util/thread_map.h"
  10 #include "util/lock-contention.h"
  11 #include <linux/zalloc.h>
  12 #include <linux/string.h>
  13 #include <bpf/bpf.h>
  14
  15 #include "bpf_skel/lock_contention.skel.h"
  16 #include "bpf_skel/lock_data.h"
  17
  18 static struct lock_contention_bpf *skel;
  19
  20 int lock_contention_prepare(struct lock_contention *con)
  21 {
  22         int i, fd;
  23         int ncpus = 1, ntasks = 1, ntypes = 1, naddrs = 1;
  24         struct evlist *evlist = con->evlist;
  25         struct target *target = con->target;
  26
  27         skel = lock_contention_bpf__open();
  28         if (!skel) {
  29                 pr_err("Failed to open lock-contention BPF skeleton\n");
  30                 return -1;
  31         }
  32
  33         bpf_map__set_value_size(skel->maps.stacks, con->max_stack * sizeof(u64));
  34         bpf_map__set_max_entries(skel->maps.lock_stat, con->map_nr_entries);
  35         bpf_map__set_max_entries(skel->maps.tstamp, con->map_nr_entries);
  36
  37         if (con->aggr_mode == LOCK_AGGR_TASK)
  38                 bpf_map__set_max_entries(skel->maps.task_data, con->map_nr_entries);
  39         else
  40                 bpf_map__set_max_entries(skel->maps.task_data, 1);
  41
  42         if (con->save_callstack)
  43                 bpf_map__set_max_entries(skel->maps.stacks, con->map_nr_entries);
  44         else
  45                 bpf_map__set_max_entries(skel->maps.stacks, 1);
  46
  47         if (target__has_cpu(target))
  48                 ncpus = perf_cpu_map__nr(evlist->core.user_requested_cpus);
  49         if (target__has_task(target))
  50                 ntasks = perf_thread_map__nr(evlist->core.threads);
  51         if (con->filters->nr_types)
  52                 ntypes = con->filters->nr_types;
  53
  54         /* resolve lock name filters to addr */
  55         if (con->filters->nr_syms) {
  56                 struct symbol *sym;
  57                 struct map *kmap;
  58                 unsigned long *addrs;
  59
  60                 for (i = 0; i < con->filters->nr_syms; i++) {
  61                         sym = machine__find_kernel_symbol_by_name(con->machine,
  62                                                                   con->filters->syms[i],
  63                                                                   &kmap);
  64                         if (sym == NULL) {
  65                                 pr_warning("ignore unknown symbol: %s\n",
  66                                            con->filters->syms[i]);
  67                                 continue;
  68                         }
  69
  70                         addrs = realloc(con->filters->addrs,
  71                                         (con->filters->nr_addrs + 1) * sizeof(*addrs));
  72                         if (addrs == NULL) {
  73                                 pr_warning("memory allocation failure\n");
  74                                 continue;
  75                         }
  76
  77                         addrs[con->filters->nr_addrs++] = kmap->unmap_ip(kmap, sym->start);
  78                         con->filters->addrs = addrs;
  79                 }
  80                 naddrs = con->filters->nr_addrs;
  81         }
  82
  83         bpf_map__set_max_entries(skel->maps.cpu_filter, ncpus);
  84         bpf_map__set_max_entries(skel->maps.task_filter, ntasks);
  85         bpf_map__set_max_entries(skel->maps.type_filter, ntypes);
  86         bpf_map__set_max_entries(skel->maps.addr_filter, naddrs);
  87
  88         if (lock_contention_bpf__load(skel) < 0) {
  89                 pr_err("Failed to load lock-contention BPF skeleton\n");
  90                 return -1;
  91         }
  92
  93         if (target__has_cpu(target)) {
  94                 u32 cpu;
  95                 u8 val = 1;
  96
  97                 skel->bss->has_cpu = 1;
  98                 fd = bpf_map__fd(skel->maps.cpu_filter);
  99
 100                 for (i = 0; i < ncpus; i++) {
 101                         cpu = perf_cpu_map__cpu(evlist->core.user_requested_cpus, i).cpu;
 102                         bpf_map_update_elem(fd, &cpu, &val, BPF_ANY);
 103                 }
 104         }
 105
 106         if (target__has_task(target)) {
 107                 u32 pid;
 108                 u8 val = 1;
 109
 110                 skel->bss->has_task = 1;
 111                 fd = bpf_map__fd(skel->maps.task_filter);
 112
 113                 for (i = 0; i < ntasks; i++) {
 114                         pid = perf_thread_map__pid(evlist->core.threads, i);
 115                         bpf_map_update_elem(fd, &pid, &val, BPF_ANY);
 116                 }
 117         }
 118
 119         if (target__none(target) && evlist->workload.pid > 0) {
 120                 u32 pid = evlist->workload.pid;
 121                 u8 val = 1;
 122
 123                 skel->bss->has_task = 1;
 124                 fd = bpf_map__fd(skel->maps.task_filter);
 125                 bpf_map_update_elem(fd, &pid, &val, BPF_ANY);
 126         }
 127
 128         if (con->filters->nr_types) {
 129                 u8 val = 1;
 130
 131                 skel->bss->has_type = 1;
 132                 fd = bpf_map__fd(skel->maps.type_filter);
 133
 134                 for (i = 0; i < con->filters->nr_types; i++)
 135                         bpf_map_update_elem(fd, &con->filters->types[i], &val, BPF_ANY);
 136         }
 137
 138         if (con->filters->nr_addrs) {
 139                 u8 val = 1;
 140
 141                 skel->bss->has_addr = 1;
 142                 fd = bpf_map__fd(skel->maps.addr_filter);
 143
 144                 for (i = 0; i < con->filters->nr_addrs; i++)
 145                         bpf_map_update_elem(fd, &con->filters->addrs[i], &val, BPF_ANY);
 146         }
 147
 148         /* these don't work well if in the rodata section */
 149         skel->bss->stack_skip = con->stack_skip;
 150         skel->bss->aggr_mode = con->aggr_mode;
 151         skel->bss->needs_callstack = con->save_callstack;
 152         skel->bss->lock_owner = con->owner;
 153
 154         lock_contention_bpf__attach(skel);
 155         return 0;
 156 }
 157
 158 int lock_contention_start(void)
 159 {
 160         skel->bss->enabled = 1;
 161         return 0;
 162 }
 163
 164 int lock_contention_stop(void)
 165 {
 166         skel->bss->enabled = 0;
 167         return 0;
 168 }
 169
 170 static const char *lock_contention_get_name(struct lock_contention *con,
 171                                             struct contention_key *key,
 172                                             u64 *stack_trace)
 173 {
 174         int idx = 0;
 175         u64 addr;
 176         const char *name = "";
 177         static char name_buf[KSYM_NAME_LEN];
 178         struct symbol *sym;
 179         struct map *kmap;
 180         struct machine *machine = con->machine;
 181
 182         if (con->aggr_mode == LOCK_AGGR_TASK) {
 183                 struct contention_task_data task;
 184                 int pid = key->pid;
 185                 int task_fd = bpf_map__fd(skel->maps.task_data);
 186
 187                 /* do not update idle comm which contains CPU number */
 188                 if (pid) {
 189                         struct thread *t = __machine__findnew_thread(machine, /*pid=*/-1, pid);
 190
 191                         if (t == NULL)
 192                                 return name;
 193                         if (!bpf_map_lookup_elem(task_fd, &pid, &task) &&
 194                             thread__set_comm(t, task.comm, /*timestamp=*/0))
 195                                 name = task.comm;
 196                 }
 197                 return name;
 198         }
 199
 200         if (con->aggr_mode == LOCK_AGGR_ADDR) {
 201                 sym = machine__find_kernel_symbol(machine, key->lock_addr, &kmap);
 202                 if (sym)
 203                         name = sym->name;
 204                 return name;
 205         }
 206
 207         /* LOCK_AGGR_CALLER: skip lock internal functions */
 208         while (machine__is_lock_function(machine, stack_trace[idx]) &&
 209                idx < con->max_stack - 1)
 210                 idx++;
 211
 212         addr = stack_trace[idx];
 213         sym = machine__find_kernel_symbol(machine, addr, &kmap);
 214
 215         if (sym) {
 216                 unsigned long offset;
 217
 218                 offset = kmap->map_ip(kmap, addr) - sym->start;
 219
 220                 if (offset == 0)
 221                         return sym->name;
 222
 223                 snprintf(name_buf, sizeof(name_buf), "%s+%#lx", sym->name, offset);
 224         } else {
 225                 snprintf(name_buf, sizeof(name_buf), "%#lx", (unsigned long)addr);
 226         }
 227
 228         return name_buf;
 229 }
 230
 231 int lock_contention_read(struct lock_contention *con)
 232 {
 233         int fd, stack, err = 0;
 234         struct contention_key *prev_key, key;
 235         struct contention_data data = {};
 236         struct lock_stat *st = NULL;
 237         struct machine *machine = con->machine;
 238         u64 *stack_trace;
 239         size_t stack_size = con->max_stack * sizeof(*stack_trace);
 240
 241         fd = bpf_map__fd(skel->maps.lock_stat);
 242         stack = bpf_map__fd(skel->maps.stacks);
 243
 244         con->lost = skel->bss->lost;
 245
 246         stack_trace = zalloc(stack_size);
 247         if (stack_trace == NULL)
 248                 return -1;
 249
 250         if (con->aggr_mode == LOCK_AGGR_TASK) {
 251                 struct thread *idle = __machine__findnew_thread(machine,
 252                                                                 /*pid=*/0,
 253                                                                 /*tid=*/0);
 254                 thread__set_comm(idle, "swapper", /*timestamp=*/0);
 255         }
 256
 257         /* make sure it loads the kernel map */
 258         map__load(maps__first(machine->kmaps));
 259
 260         prev_key = NULL;
 261         while (!bpf_map_get_next_key(fd, prev_key, &key)) {
 262                 s64 ls_key;
 263                 const char *name;
 264
 265                 /* to handle errors in the loop body */
 266                 err = -1;
 267
 268                 bpf_map_lookup_elem(fd, &key, &data);
 269                 if (con->save_callstack) {
 270                         bpf_map_lookup_elem(stack, &key.stack_id, stack_trace);
 271
 272                         if (!match_callstack_filter(machine, stack_trace))
 273                                 goto next;
 274                 }
 275
 276                 switch (con->aggr_mode) {
 277                 case LOCK_AGGR_CALLER:
 278                         ls_key = key.stack_id;
 279                         break;
 280                 case LOCK_AGGR_TASK:
 281                         ls_key = key.pid;
 282                         break;
 283                 case LOCK_AGGR_ADDR:
 284                         ls_key = key.lock_addr;
 285                         break;
 286                 default:
 287                         goto next;
 288                 }
 289
 290                 st = lock_stat_find(ls_key);
 291                 if (st != NULL) {
 292                         st->wait_time_total += data.total_time;
 293                         if (st->wait_time_max < data.max_time)
 294                                 st->wait_time_max = data.max_time;
 295                         if (st->wait_time_min > data.min_time)
 296                                 st->wait_time_min = data.min_time;
 297
 298                         st->nr_contended += data.count;
 299                         if (st->nr_contended)
 300                                 st->avg_wait_time = st->wait_time_total / st->nr_contended;
 301                         goto next;
 302                 }
 303
 304                 name = lock_contention_get_name(con, &key, stack_trace);
 305                 st = lock_stat_findnew(ls_key, name, data.flags);
 306                 if (st == NULL)
 307                         break;
 308
 309                 st->nr_contended = data.count;
 310                 st->wait_time_total = data.total_time;
 311                 st->wait_time_max = data.max_time;
 312                 st->wait_time_min = data.min_time;
 313
 314                 if (data.count)
 315                         st->avg_wait_time = data.total_time / data.count;
 316
 317                 if (con->save_callstack) {
 318                         st->callstack = memdup(stack_trace, stack_size);
 319                         if (st->callstack == NULL)
 320                                 break;
 321                 }
 322
 323 next:
 324                 prev_key = &key;
 325
 326                 /* we're fine now, reset the error */
 327                 err = 0;
 328         }
 329
 330         free(stack_trace);
 331
 332         return err;
 333 }
 334
 335 int lock_contention_finish(void)
 336 {
 337         if (skel) {
 338                 skel->bss->enabled = 0;
 339                 lock_contention_bpf__destroy(skel);
 340         }
 341
 342         return 0;
 343 }