1 // SPDX-License-Identifier: GPL-2.0 2 #include "util/bpf_counter.h" 3 #include "util/debug.h" 4 #include "util/evsel.h" 5 #include "util/evlist.h" 6 #include "util/off_cpu.h" 7 #include "util/perf-hooks.h" 8 #include "util/record.h" 9 #include "util/session.h" 10 #include "util/target.h" 11 #include "util/cpumap.h" 12 #include "util/thread_map.h" 13 #include "util/cgroup.h" 14 #include <bpf/bpf.h> 15 16 #include "bpf_skel/off_cpu.skel.h" 17 18 #define MAX_STACKS 32 19 /* we don't need actual timestamp, just want to put the samples at last */ 20 #define OFF_CPU_TIMESTAMP (~0ull << 32) 21 22 static struct off_cpu_bpf *skel; 23 24 struct off_cpu_key { 25 u32 pid; 26 u32 tgid; 27 u32 stack_id; 28 u32 state; 29 u64 cgroup_id; 30 }; 31 32 union off_cpu_data { 33 struct perf_event_header hdr; 34 u64 array[1024 / sizeof(u64)]; 35 }; 36 37 static int off_cpu_config(struct evlist *evlist) 38 { 39 struct evsel *evsel; 40 struct perf_event_attr attr = { 41 .type = PERF_TYPE_SOFTWARE, 42 .config = PERF_COUNT_SW_BPF_OUTPUT, 43 .size = sizeof(attr), /* to capture ABI version */ 44 }; 45 char *evname = strdup(OFFCPU_EVENT); 46 47 if (evname == NULL) 48 return -ENOMEM; 49 50 evsel = evsel__new(&attr); 51 if (!evsel) { 52 free(evname); 53 return -ENOMEM; 54 } 55 56 evsel->core.attr.freq = 1; 57 evsel->core.attr.sample_period = 1; 58 /* off-cpu analysis depends on stack trace */ 59 evsel->core.attr.sample_type = PERF_SAMPLE_CALLCHAIN; 60 61 evlist__add(evlist, evsel); 62 63 free(evsel->name); 64 evsel->name = evname; 65 66 return 0; 67 } 68 69 static void off_cpu_start(void *arg) 70 { 71 struct evlist *evlist = arg; 72 73 /* update task filter for the given workload */ 74 if (!skel->bss->has_cpu && !skel->bss->has_task && 75 perf_thread_map__pid(evlist->core.threads, 0) != -1) { 76 int fd; 77 u32 pid; 78 u8 val = 1; 79 80 skel->bss->has_task = 1; 81 fd = bpf_map__fd(skel->maps.task_filter); 82 pid = perf_thread_map__pid(evlist->core.threads, 0); 83 bpf_map_update_elem(fd, &pid, &val, BPF_ANY); 84 } 85 86 skel->bss->enabled = 1; 87 } 88 89 static void off_cpu_finish(void *arg __maybe_unused) 90 { 91 skel->bss->enabled = 0; 92 off_cpu_bpf__destroy(skel); 93 } 94 95 /* v5.18 kernel added prev_state arg, so it needs to check the signature */ 96 static void check_sched_switch_args(void) 97 { 98 const struct btf *btf = bpf_object__btf(skel->obj); 99 const struct btf_type *t1, *t2, *t3; 100 u32 type_id; 101 102 type_id = btf__find_by_name_kind(btf, "bpf_trace_sched_switch", 103 BTF_KIND_TYPEDEF); 104 if ((s32)type_id < 0) 105 return; 106 107 t1 = btf__type_by_id(btf, type_id); 108 if (t1 == NULL) 109 return; 110 111 t2 = btf__type_by_id(btf, t1->type); 112 if (t2 == NULL || !btf_is_ptr(t2)) 113 return; 114 115 t3 = btf__type_by_id(btf, t2->type); 116 if (t3 && btf_is_func_proto(t3) && btf_vlen(t3) == 4) { 117 /* new format: pass prev_state as 4th arg */ 118 skel->rodata->has_prev_state = true; 119 } 120 } 121 122 int off_cpu_prepare(struct evlist *evlist, struct target *target, 123 struct record_opts *opts) 124 { 125 int err, fd, i; 126 int ncpus = 1, ntasks = 1, ncgrps = 1; 127 128 if (off_cpu_config(evlist) < 0) { 129 pr_err("Failed to config off-cpu BPF event\n"); 130 return -1; 131 } 132 133 skel = off_cpu_bpf__open(); 134 if (!skel) { 135 pr_err("Failed to open off-cpu BPF skeleton\n"); 136 return -1; 137 } 138 139 /* don't need to set cpu filter for system-wide mode */ 140 if (target->cpu_list) { 141 ncpus = perf_cpu_map__nr(evlist->core.user_requested_cpus); 142 bpf_map__set_max_entries(skel->maps.cpu_filter, ncpus); 143 } 144 145 if (target__has_task(target)) { 146 ntasks = perf_thread_map__nr(evlist->core.threads); 147 bpf_map__set_max_entries(skel->maps.task_filter, ntasks); 148 } 149 150 if (evlist__first(evlist)->cgrp) { 151 ncgrps = evlist->core.nr_entries - 1; /* excluding a dummy */ 152 bpf_map__set_max_entries(skel->maps.cgroup_filter, ncgrps); 153 154 if (!cgroup_is_v2("perf_event")) 155 skel->rodata->uses_cgroup_v1 = true; 156 } 157 158 if (opts->record_cgroup) { 159 skel->rodata->needs_cgroup = true; 160 161 if (!cgroup_is_v2("perf_event")) 162 skel->rodata->uses_cgroup_v1 = true; 163 } 164 165 set_max_rlimit(); 166 check_sched_switch_args(); 167 168 err = off_cpu_bpf__load(skel); 169 if (err) { 170 pr_err("Failed to load off-cpu skeleton\n"); 171 goto out; 172 } 173 174 if (target->cpu_list) { 175 u32 cpu; 176 u8 val = 1; 177 178 skel->bss->has_cpu = 1; 179 fd = bpf_map__fd(skel->maps.cpu_filter); 180 181 for (i = 0; i < ncpus; i++) { 182 cpu = perf_cpu_map__cpu(evlist->core.user_requested_cpus, i).cpu; 183 bpf_map_update_elem(fd, &cpu, &val, BPF_ANY); 184 } 185 } 186 187 if (target__has_task(target)) { 188 u32 pid; 189 u8 val = 1; 190 191 skel->bss->has_task = 1; 192 fd = bpf_map__fd(skel->maps.task_filter); 193 194 for (i = 0; i < ntasks; i++) { 195 pid = perf_thread_map__pid(evlist->core.threads, i); 196 bpf_map_update_elem(fd, &pid, &val, BPF_ANY); 197 } 198 } 199 200 if (evlist__first(evlist)->cgrp) { 201 struct evsel *evsel; 202 u8 val = 1; 203 204 skel->bss->has_cgroup = 1; 205 fd = bpf_map__fd(skel->maps.cgroup_filter); 206 207 evlist__for_each_entry(evlist, evsel) { 208 struct cgroup *cgrp = evsel->cgrp; 209 210 if (cgrp == NULL) 211 continue; 212 213 if (!cgrp->id && read_cgroup_id(cgrp) < 0) { 214 pr_err("Failed to read cgroup id of %s\n", 215 cgrp->name); 216 goto out; 217 } 218 219 bpf_map_update_elem(fd, &cgrp->id, &val, BPF_ANY); 220 } 221 } 222 223 err = off_cpu_bpf__attach(skel); 224 if (err) { 225 pr_err("Failed to attach off-cpu BPF skeleton\n"); 226 goto out; 227 } 228 229 if (perf_hooks__set_hook("record_start", off_cpu_start, evlist) || 230 perf_hooks__set_hook("record_end", off_cpu_finish, evlist)) { 231 pr_err("Failed to attach off-cpu skeleton\n"); 232 goto out; 233 } 234 235 return 0; 236 237 out: 238 off_cpu_bpf__destroy(skel); 239 return -1; 240 } 241 242 int off_cpu_write(struct perf_session *session) 243 { 244 int bytes = 0, size; 245 int fd, stack; 246 u64 sample_type, val, sid = 0; 247 struct evsel *evsel; 248 struct perf_data_file *file = &session->data->file; 249 struct off_cpu_key prev, key; 250 union off_cpu_data data = { 251 .hdr = { 252 .type = PERF_RECORD_SAMPLE, 253 .misc = PERF_RECORD_MISC_USER, 254 }, 255 }; 256 u64 tstamp = OFF_CPU_TIMESTAMP; 257 258 skel->bss->enabled = 0; 259 260 evsel = evlist__find_evsel_by_str(session->evlist, OFFCPU_EVENT); 261 if (evsel == NULL) { 262 pr_err("%s evsel not found\n", OFFCPU_EVENT); 263 return 0; 264 } 265 266 sample_type = evsel->core.attr.sample_type; 267 268 if (sample_type & (PERF_SAMPLE_ID | PERF_SAMPLE_IDENTIFIER)) { 269 if (evsel->core.id) 270 sid = evsel->core.id[0]; 271 } 272 273 fd = bpf_map__fd(skel->maps.off_cpu); 274 stack = bpf_map__fd(skel->maps.stacks); 275 memset(&prev, 0, sizeof(prev)); 276 277 while (!bpf_map_get_next_key(fd, &prev, &key)) { 278 int n = 1; /* start from perf_event_header */ 279 int ip_pos = -1; 280 281 bpf_map_lookup_elem(fd, &key, &val); 282 283 if (sample_type & PERF_SAMPLE_IDENTIFIER) 284 data.array[n++] = sid; 285 if (sample_type & PERF_SAMPLE_IP) { 286 ip_pos = n; 287 data.array[n++] = 0; /* will be updated */ 288 } 289 if (sample_type & PERF_SAMPLE_TID) 290 data.array[n++] = (u64)key.pid << 32 | key.tgid; 291 if (sample_type & PERF_SAMPLE_TIME) 292 data.array[n++] = tstamp; 293 if (sample_type & PERF_SAMPLE_ID) 294 data.array[n++] = sid; 295 if (sample_type & PERF_SAMPLE_CPU) 296 data.array[n++] = 0; 297 if (sample_type & PERF_SAMPLE_PERIOD) 298 data.array[n++] = val; 299 if (sample_type & PERF_SAMPLE_CALLCHAIN) { 300 int len = 0; 301 302 /* data.array[n] is callchain->nr (updated later) */ 303 data.array[n + 1] = PERF_CONTEXT_USER; 304 data.array[n + 2] = 0; 305 306 bpf_map_lookup_elem(stack, &key.stack_id, &data.array[n + 2]); 307 while (data.array[n + 2 + len]) 308 len++; 309 310 /* update length of callchain */ 311 data.array[n] = len + 1; 312 313 /* update sample ip with the first callchain entry */ 314 if (ip_pos >= 0) 315 data.array[ip_pos] = data.array[n + 2]; 316 317 /* calculate sample callchain data array length */ 318 n += len + 2; 319 } 320 if (sample_type & PERF_SAMPLE_CGROUP) 321 data.array[n++] = key.cgroup_id; 322 /* TODO: handle more sample types */ 323 324 size = n * sizeof(u64); 325 data.hdr.size = size; 326 bytes += size; 327 328 if (perf_data_file__write(file, &data, size) < 0) { 329 pr_err("failed to write perf data, error: %m\n"); 330 return bytes; 331 } 332 333 prev = key; 334 /* increase dummy timestamp to sort later samples */ 335 tstamp++; 336 } 337 return bytes; 338 } 339