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                 bpf_map__set_max_entries(skel->maps.stacks, 1);
  40         } else {
  41                 bpf_map__set_max_entries(skel->maps.task_data, 1);
  42                 bpf_map__set_max_entries(skel->maps.stacks, con->map_nr_entries);
  43         }
  44
  45         if (target__has_cpu(target))
  46                 ncpus = perf_cpu_map__nr(evlist->core.user_requested_cpus);
  47         if (target__has_task(target))
  48                 ntasks = perf_thread_map__nr(evlist->core.threads);
  49         if (con->filters->nr_types)
  50                 ntypes = con->filters->nr_types;
  51
  52         /* resolve lock name filters to addr */
  53         if (con->filters->nr_syms) {
  54                 struct symbol *sym;
  55                 struct map *kmap;
  56                 unsigned long *addrs;
  57
  58                 for (i = 0; i < con->filters->nr_syms; i++) {
  59                         sym = machine__find_kernel_symbol_by_name(con->machine,
  60                                                                   con->filters->syms[i],
  61                                                                   &kmap);
  62                         if (sym == NULL) {
  63                                 pr_warning("ignore unknown symbol: %s\n",
  64                                            con->filters->syms[i]);
  65                                 continue;
  66                         }
  67
  68                         addrs = realloc(con->filters->addrs,
  69                                         (con->filters->nr_addrs + 1) * sizeof(*addrs));
  70                         if (addrs == NULL) {
  71                                 pr_warning("memory allocation failure\n");
  72                                 continue;
  73                         }
  74
  75                         addrs[con->filters->nr_addrs++] = kmap->unmap_ip(kmap, sym->start);
  76                         con->filters->addrs = addrs;
  77                 }
  78                 naddrs = con->filters->nr_addrs;
  79         }
  80
  81         bpf_map__set_max_entries(skel->maps.cpu_filter, ncpus);
  82         bpf_map__set_max_entries(skel->maps.task_filter, ntasks);
  83         bpf_map__set_max_entries(skel->maps.type_filter, ntypes);
  84         bpf_map__set_max_entries(skel->maps.addr_filter, naddrs);
  85
  86         if (lock_contention_bpf__load(skel) < 0) {
  87                 pr_err("Failed to load lock-contention BPF skeleton\n");
  88                 return -1;
  89         }
  90
  91         if (target__has_cpu(target)) {
  92                 u32 cpu;
  93                 u8 val = 1;
  94
  95                 skel->bss->has_cpu = 1;
  96                 fd = bpf_map__fd(skel->maps.cpu_filter);
  97
  98                 for (i = 0; i < ncpus; i++) {
  99                         cpu = perf_cpu_map__cpu(evlist->core.user_requested_cpus, i).cpu;
 100                         bpf_map_update_elem(fd, &cpu, &val, BPF_ANY);
 101                 }
 102         }
 103
 104         if (target__has_task(target)) {
 105                 u32 pid;
 106                 u8 val = 1;
 107
 108                 skel->bss->has_task = 1;
 109                 fd = bpf_map__fd(skel->maps.task_filter);
 110
 111                 for (i = 0; i < ntasks; i++) {
 112                         pid = perf_thread_map__pid(evlist->core.threads, i);
 113                         bpf_map_update_elem(fd, &pid, &val, BPF_ANY);
 114                 }
 115         }
 116
 117         if (target__none(target) && evlist->workload.pid > 0) {
 118                 u32 pid = evlist->workload.pid;
 119                 u8 val = 1;
 120
 121                 skel->bss->has_task = 1;
 122                 fd = bpf_map__fd(skel->maps.task_filter);
 123                 bpf_map_update_elem(fd, &pid, &val, BPF_ANY);
 124         }
 125
 126         if (con->filters->nr_types) {
 127                 u8 val = 1;
 128
 129                 skel->bss->has_type = 1;
 130                 fd = bpf_map__fd(skel->maps.type_filter);
 131
 132                 for (i = 0; i < con->filters->nr_types; i++)
 133                         bpf_map_update_elem(fd, &con->filters->types[i], &val, BPF_ANY);
 134         }
 135
 136         if (con->filters->nr_addrs) {
 137                 u8 val = 1;
 138
 139                 skel->bss->has_addr = 1;
 140                 fd = bpf_map__fd(skel->maps.addr_filter);
 141
 142                 for (i = 0; i < con->filters->nr_addrs; i++)
 143                         bpf_map_update_elem(fd, &con->filters->addrs[i], &val, BPF_ANY);
 144         }
 145
 146         /* these don't work well if in the rodata section */
 147         skel->bss->stack_skip = con->stack_skip;
 148         skel->bss->aggr_mode = con->aggr_mode;
 149
 150         lock_contention_bpf__attach(skel);
 151         return 0;
 152 }
 153
 154 int lock_contention_start(void)
 155 {
 156         skel->bss->enabled = 1;
 157         return 0;
 158 }
 159
 160 int lock_contention_stop(void)
 161 {
 162         skel->bss->enabled = 0;
 163         return 0;
 164 }
 165
 166 int lock_contention_read(struct lock_contention *con)
 167 {
 168         int fd, stack, task_fd, err = 0;
 169         struct contention_key *prev_key, key;
 170         struct contention_data data = {};
 171         struct lock_stat *st = NULL;
 172         struct machine *machine = con->machine;
 173         u64 *stack_trace;
 174         size_t stack_size = con->max_stack * sizeof(*stack_trace);
 175
 176         fd = bpf_map__fd(skel->maps.lock_stat);
 177         stack = bpf_map__fd(skel->maps.stacks);
 178         task_fd = bpf_map__fd(skel->maps.task_data);
 179
 180         con->lost = skel->bss->lost;
 181
 182         stack_trace = zalloc(stack_size);
 183         if (stack_trace == NULL)
 184                 return -1;
 185
 186         if (con->aggr_mode == LOCK_AGGR_TASK) {
 187                 struct thread *idle = __machine__findnew_thread(machine,
 188                                                                 /*pid=*/0,
 189                                                                 /*tid=*/0);
 190                 thread__set_comm(idle, "swapper", /*timestamp=*/0);
 191         }
 192
 193         /* make sure it loads the kernel map */
 194         map__load(maps__first(machine->kmaps));
 195
 196         prev_key = NULL;
 197         while (!bpf_map_get_next_key(fd, prev_key, &key)) {
 198                 struct map *kmap;
 199                 struct symbol *sym;
 200                 int idx = 0;
 201                 s32 stack_id;
 202
 203                 /* to handle errors in the loop body */
 204                 err = -1;
 205
 206                 bpf_map_lookup_elem(fd, &key, &data);
 207                 st = zalloc(sizeof(*st));
 208                 if (st == NULL)
 209                         break;
 210
 211                 st->nr_contended = data.count;
 212                 st->wait_time_total = data.total_time;
 213                 st->wait_time_max = data.max_time;
 214                 st->wait_time_min = data.min_time;
 215
 216                 if (data.count)
 217                         st->avg_wait_time = data.total_time / data.count;
 218
 219                 st->flags = data.flags;
 220                 st->addr = key.aggr_key;
 221
 222                 if (con->aggr_mode == LOCK_AGGR_TASK) {
 223                         struct contention_task_data task;
 224                         struct thread *t;
 225                         int pid = key.aggr_key;
 226
 227                         /* do not update idle comm which contains CPU number */
 228                         if (st->addr) {
 229                                 bpf_map_lookup_elem(task_fd, &pid, &task);
 230                                 t = __machine__findnew_thread(machine, /*pid=*/-1, pid);
 231                                 thread__set_comm(t, task.comm, /*timestamp=*/0);
 232                         }
 233                         goto next;
 234                 }
 235
 236                 if (con->aggr_mode == LOCK_AGGR_ADDR) {
 237                         sym = machine__find_kernel_symbol(machine, st->addr, &kmap);
 238                         if (sym)
 239                                 st->name = strdup(sym->name);
 240                         goto next;
 241                 }
 242
 243                 stack_id = key.aggr_key;
 244                 bpf_map_lookup_elem(stack, &stack_id, stack_trace);
 245
 246                 /* skip lock internal functions */
 247                 while (machine__is_lock_function(machine, stack_trace[idx]) &&
 248                        idx < con->max_stack - 1)
 249                         idx++;
 250
 251                 st->addr = stack_trace[idx];
 252                 sym = machine__find_kernel_symbol(machine, st->addr, &kmap);
 253
 254                 if (sym) {
 255                         unsigned long offset;
 256                         int ret = 0;
 257
 258                         offset = kmap->map_ip(kmap, st->addr) - sym->start;
 259
 260                         if (offset)
 261                                 ret = asprintf(&st->name, "%s+%#lx", sym->name, offset);
 262                         else
 263                                 st->name = strdup(sym->name);
 264
 265                         if (ret < 0 || st->name == NULL)
 266                                 break;
 267                 } else if (asprintf(&st->name, "%#lx", (unsigned long)st->addr) < 0) {
 268                         break;
 269                 }
 270
 271                 if (verbose > 0) {
 272                         st->callstack = memdup(stack_trace, stack_size);
 273                         if (st->callstack == NULL)
 274                                 break;
 275                 }
 276 next:
 277                 hlist_add_head(&st->hash_entry, con->result);
 278                 prev_key = &key;
 279
 280                 /* we're fine now, reset the values */
 281                 st = NULL;
 282                 err = 0;
 283         }
 284
 285         free(stack_trace);
 286         if (st) {
 287                 free(st->name);
 288                 free(st);
 289         }
 290
 291         return err;
 292 }
 293
 294 int lock_contention_finish(void)
 295 {
 296         if (skel) {
 297                 skel->bss->enabled = 0;
 298                 lock_contention_bpf__destroy(skel);
 299         }
 300
 301         return 0;
 302 }