samples/bpf/trace_event_user.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /* Copyright (c) 2016 Facebook
   3  */
   4 #include <stdio.h>
   5 #include <unistd.h>
   6 #include <stdlib.h>
   7 #include <stdbool.h>
   8 #include <string.h>
   9 #include <linux/perf_event.h>
  10 #include <linux/bpf.h>
  11 #include <signal.h>
  12 #include <errno.h>
  13 #include <sys/resource.h>
  14 #include <bpf/bpf.h>
  15 #include <bpf/libbpf.h>
  16 #include "perf-sys.h"
  17 #include "trace_helpers.h"
  18
  19 #define SAMPLE_FREQ 50
  20
  21 static int pid;
  22 /* counts, stackmap */
  23 static int map_fd[2];
  24 struct bpf_program *prog;
  25 static bool sys_read_seen, sys_write_seen;
  26
  27 static void print_ksym(__u64 addr)
  28 {
  29         struct ksym *sym;
  30
  31         if (!addr)
  32                 return;
  33         sym = ksym_search(addr);
  34         if (!sym) {
  35                 printf("ksym not found. Is kallsyms loaded?\n");
  36                 return;
  37         }
  38
  39         printf("%s;", sym->name);
  40         if (!strstr(sym->name, "sys_read"))
  41                 sys_read_seen = true;
  42         else if (!strstr(sym->name, "sys_write"))
  43                 sys_write_seen = true;
  44 }
  45
  46 static void print_addr(__u64 addr)
  47 {
  48         if (!addr)
  49                 return;
  50         printf("%llx;", addr);
  51 }
  52
  53 #define TASK_COMM_LEN 16
  54
  55 struct key_t {
  56         char comm[TASK_COMM_LEN];
  57         __u32 kernstack;
  58         __u32 userstack;
  59 };
  60
  61 static void print_stack(struct key_t *key, __u64 count)
  62 {
  63         __u64 ip[PERF_MAX_STACK_DEPTH] = {};
  64         static bool warned;
  65         int i;
  66
  67         printf("%3lld %s;", count, key->comm);
  68         if (bpf_map_lookup_elem(map_fd[1], &key->kernstack, ip) != 0) {
  69                 printf("---;");
  70         } else {
  71                 for (i = PERF_MAX_STACK_DEPTH - 1; i >= 0; i--)
  72                         print_ksym(ip[i]);
  73         }
  74         printf("-;");
  75         if (bpf_map_lookup_elem(map_fd[1], &key->userstack, ip) != 0) {
  76                 printf("---;");
  77         } else {
  78                 for (i = PERF_MAX_STACK_DEPTH - 1; i >= 0; i--)
  79                         print_addr(ip[i]);
  80         }
  81         if (count < 6)
  82                 printf("\r");
  83         else
  84                 printf("\n");
  85
  86         if (key->kernstack == -EEXIST && !warned) {
  87                 printf("stackmap collisions seen. Consider increasing size\n");
  88                 warned = true;
  89         } else if ((int)key->kernstack < 0 && (int)key->userstack < 0) {
  90                 printf("err stackid %d %d\n", key->kernstack, key->userstack);
  91         }
  92 }
  93
  94 static void err_exit(int err)
  95 {
  96         kill(pid, SIGKILL);
  97         exit(err);
  98 }
  99
 100 static void print_stacks(void)
 101 {
 102         struct key_t key = {}, next_key;
 103         __u64 value;
 104         __u32 stackid = 0, next_id;
 105         int error = 1, fd = map_fd[0], stack_map = map_fd[1];
 106
 107         sys_read_seen = sys_write_seen = false;
 108         while (bpf_map_get_next_key(fd, &key, &next_key) == 0) {
 109                 bpf_map_lookup_elem(fd, &next_key, &value);
 110                 print_stack(&next_key, value);
 111                 bpf_map_delete_elem(fd, &next_key);
 112                 key = next_key;
 113         }
 114         printf("\n");
 115         if (!sys_read_seen || !sys_write_seen) {
 116                 printf("BUG kernel stack doesn't contain sys_read() and sys_write()\n");
 117                 err_exit(error);
 118         }
 119
 120         /* clear stack map */
 121         while (bpf_map_get_next_key(stack_map, &stackid, &next_id) == 0) {
 122                 bpf_map_delete_elem(stack_map, &next_id);
 123                 stackid = next_id;
 124         }
 125 }
 126
 127 static inline int generate_load(void)
 128 {
 129         if (system("dd if=/dev/zero of=/dev/null count=5000k status=none") < 0) {
 130                 printf("failed to generate some load with dd: %s\n", strerror(errno));
 131                 return -1;
 132         }
 133
 134         return 0;
 135 }
 136
 137 static void test_perf_event_all_cpu(struct perf_event_attr *attr)
 138 {
 139         int nr_cpus = sysconf(_SC_NPROCESSORS_ONLN);
 140         struct bpf_link **links = calloc(nr_cpus, sizeof(struct bpf_link *));
 141         int i, pmu_fd, error = 1;
 142
 143         if (!links) {
 144                 printf("malloc of links failed\n");
 145                 goto err;
 146         }
 147
 148         /* system wide perf event, no need to inherit */
 149         attr->inherit = 0;
 150
 151         /* open perf_event on all cpus */
 152         for (i = 0; i < nr_cpus; i++) {
 153                 pmu_fd = sys_perf_event_open(attr, -1, i, -1, 0);
 154                 if (pmu_fd < 0) {
 155                         printf("sys_perf_event_open failed\n");
 156                         goto all_cpu_err;
 157                 }
 158                 links[i] = bpf_program__attach_perf_event(prog, pmu_fd);
 159                 if (libbpf_get_error(links[i])) {
 160                         printf("bpf_program__attach_perf_event failed\n");
 161                         links[i] = NULL;
 162                         close(pmu_fd);
 163                         goto all_cpu_err;
 164                 }
 165         }
 166
 167         if (generate_load() < 0)
 168                 goto all_cpu_err;
 169
 170         print_stacks();
 171         error = 0;
 172 all_cpu_err:
 173         for (i--; i >= 0; i--)
 174                 bpf_link__destroy(links[i]);
 175 err:
 176         free(links);
 177         if (error)
 178                 err_exit(error);
 179 }
 180
 181 static void test_perf_event_task(struct perf_event_attr *attr)
 182 {
 183         struct bpf_link *link = NULL;
 184         int pmu_fd, error = 1;
 185
 186         /* per task perf event, enable inherit so the "dd ..." command can be traced properly.
 187          * Enabling inherit will cause bpf_perf_prog_read_time helper failure.
 188          */
 189         attr->inherit = 1;
 190
 191         /* open task bound event */
 192         pmu_fd = sys_perf_event_open(attr, 0, -1, -1, 0);
 193         if (pmu_fd < 0) {
 194                 printf("sys_perf_event_open failed\n");
 195                 goto err;
 196         }
 197         link = bpf_program__attach_perf_event(prog, pmu_fd);
 198         if (libbpf_get_error(link)) {
 199                 printf("bpf_program__attach_perf_event failed\n");
 200                 link = NULL;
 201                 close(pmu_fd);
 202                 goto err;
 203         }
 204
 205         if (generate_load() < 0)
 206                 goto err;
 207
 208         print_stacks();
 209         error = 0;
 210 err:
 211         bpf_link__destroy(link);
 212         if (error)
 213                 err_exit(error);
 214 }
 215
 216 static void test_bpf_perf_event(void)
 217 {
 218         struct perf_event_attr attr_type_hw = {
 219                 .sample_freq = SAMPLE_FREQ,
 220                 .freq = 1,
 221                 .type = PERF_TYPE_HARDWARE,
 222                 .config = PERF_COUNT_HW_CPU_CYCLES,
 223         };
 224         struct perf_event_attr attr_type_sw = {
 225                 .sample_freq = SAMPLE_FREQ,
 226                 .freq = 1,
 227                 .type = PERF_TYPE_SOFTWARE,
 228                 .config = PERF_COUNT_SW_CPU_CLOCK,
 229         };
 230         struct perf_event_attr attr_hw_cache_l1d = {
 231                 .sample_freq = SAMPLE_FREQ,
 232                 .freq = 1,
 233                 .type = PERF_TYPE_HW_CACHE,
 234                 .config =
 235                         PERF_COUNT_HW_CACHE_L1D |
 236                         (PERF_COUNT_HW_CACHE_OP_READ << 8) |
 237                         (PERF_COUNT_HW_CACHE_RESULT_ACCESS << 16),
 238         };
 239         struct perf_event_attr attr_hw_cache_branch_miss = {
 240                 .sample_freq = SAMPLE_FREQ,
 241                 .freq = 1,
 242                 .type = PERF_TYPE_HW_CACHE,
 243                 .config =
 244                         PERF_COUNT_HW_CACHE_BPU |
 245                         (PERF_COUNT_HW_CACHE_OP_READ << 8) |
 246                         (PERF_COUNT_HW_CACHE_RESULT_MISS << 16),
 247         };
 248         struct perf_event_attr attr_type_raw = {
 249                 .sample_freq = SAMPLE_FREQ,
 250                 .freq = 1,
 251                 .type = PERF_TYPE_RAW,
 252                 /* Intel Instruction Retired */
 253                 .config = 0xc0,
 254         };
 255         struct perf_event_attr attr_type_raw_lock_load = {
 256                 .sample_freq = SAMPLE_FREQ,
 257                 .freq = 1,
 258                 .type = PERF_TYPE_RAW,
 259                 /* Intel MEM_UOPS_RETIRED.LOCK_LOADS */
 260                 .config = 0x21d0,
 261                 /* Request to record lock address from PEBS */
 262                 .sample_type = PERF_SAMPLE_ADDR,
 263                 /* Record address value requires precise event */
 264                 .precise_ip = 2,
 265         };
 266
 267         printf("Test HW_CPU_CYCLES\n");
 268         test_perf_event_all_cpu(&attr_type_hw);
 269         test_perf_event_task(&attr_type_hw);
 270
 271         printf("Test SW_CPU_CLOCK\n");
 272         test_perf_event_all_cpu(&attr_type_sw);
 273         test_perf_event_task(&attr_type_sw);
 274
 275         printf("Test HW_CACHE_L1D\n");
 276         test_perf_event_all_cpu(&attr_hw_cache_l1d);
 277         test_perf_event_task(&attr_hw_cache_l1d);
 278
 279         printf("Test HW_CACHE_BPU\n");
 280         test_perf_event_all_cpu(&attr_hw_cache_branch_miss);
 281         test_perf_event_task(&attr_hw_cache_branch_miss);
 282
 283         printf("Test Instruction Retired\n");
 284         test_perf_event_all_cpu(&attr_type_raw);
 285         test_perf_event_task(&attr_type_raw);
 286
 287         printf("Test Lock Load\n");
 288         test_perf_event_all_cpu(&attr_type_raw_lock_load);
 289         test_perf_event_task(&attr_type_raw_lock_load);
 290
 291         printf("*** PASS ***\n");
 292 }
 293
 294
 295 int main(int argc, char **argv)
 296 {
 297         struct bpf_object *obj = NULL;
 298         char filename[256];
 299         int error = 1;
 300
 301         snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
 302
 303         signal(SIGINT, err_exit);
 304         signal(SIGTERM, err_exit);
 305
 306         if (load_kallsyms()) {
 307                 printf("failed to process /proc/kallsyms\n");
 308                 goto cleanup;
 309         }
 310
 311         obj = bpf_object__open_file(filename, NULL);
 312         if (libbpf_get_error(obj)) {
 313                 printf("opening BPF object file failed\n");
 314                 obj = NULL;
 315                 goto cleanup;
 316         }
 317
 318         prog = bpf_object__find_program_by_name(obj, "bpf_prog1");
 319         if (!prog) {
 320                 printf("finding a prog in obj file failed\n");
 321                 goto cleanup;
 322         }
 323
 324         /* load BPF program */
 325         if (bpf_object__load(obj)) {
 326                 printf("loading BPF object file failed\n");
 327                 goto cleanup;
 328         }
 329
 330         map_fd[0] = bpf_object__find_map_fd_by_name(obj, "counts");
 331         map_fd[1] = bpf_object__find_map_fd_by_name(obj, "stackmap");
 332         if (map_fd[0] < 0 || map_fd[1] < 0) {
 333                 printf("finding a counts/stackmap map in obj file failed\n");
 334                 goto cleanup;
 335         }
 336
 337         pid = fork();
 338         if (pid == 0) {
 339                 read_trace_pipe();
 340                 return 0;
 341         } else if (pid == -1) {
 342                 printf("couldn't spawn process\n");
 343                 goto cleanup;
 344         }
 345
 346         test_bpf_perf_event();
 347         error = 0;
 348
 349 cleanup:
 350         bpf_object__close(obj);
 351         err_exit(error);
 352 }