samples/bpf/offwaketime_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 <signal.h>
   8 #include <linux/perf_event.h>
   9 #include <errno.h>
  10 #include <stdbool.h>
  11 #include <bpf/libbpf.h>
  12 #include <bpf/bpf.h>
  13 #include "trace_helpers.h"
  14
  15 #define PRINT_RAW_ADDR 0
  16
  17 /* counts, stackmap */
  18 static int map_fd[2];
  19
  20 static void print_ksym(__u64 addr)
  21 {
  22         struct ksym *sym;
  23
  24         if (!addr)
  25                 return;
  26         sym = ksym_search(addr);
  27         if (!sym) {
  28                 printf("ksym not found. Is kallsyms loaded?\n");
  29                 return;
  30         }
  31
  32         if (PRINT_RAW_ADDR)
  33                 printf("%s/%llx;", sym->name, addr);
  34         else
  35                 printf("%s;", sym->name);
  36 }
  37
  38 #define TASK_COMM_LEN 16
  39
  40 struct key_t {
  41         char waker[TASK_COMM_LEN];
  42         char target[TASK_COMM_LEN];
  43         __u32 wret;
  44         __u32 tret;
  45 };
  46
  47 static void print_stack(struct key_t *key, __u64 count)
  48 {
  49         __u64 ip[PERF_MAX_STACK_DEPTH] = {};
  50         static bool warned;
  51         int i;
  52
  53         printf("%s;", key->target);
  54         if (bpf_map_lookup_elem(map_fd[1], &key->tret, ip) != 0) {
  55                 printf("---;");
  56         } else {
  57                 for (i = PERF_MAX_STACK_DEPTH - 1; i >= 0; i--)
  58                         print_ksym(ip[i]);
  59         }
  60         printf("-;");
  61         if (bpf_map_lookup_elem(map_fd[1], &key->wret, ip) != 0) {
  62                 printf("---;");
  63         } else {
  64                 for (i = 0; i < PERF_MAX_STACK_DEPTH; i++)
  65                         print_ksym(ip[i]);
  66         }
  67         printf(";%s %lld\n", key->waker, count);
  68
  69         if ((key->tret == -EEXIST || key->wret == -EEXIST) && !warned) {
  70                 printf("stackmap collisions seen. Consider increasing size\n");
  71                 warned = true;
  72         } else if (((int)(key->tret) < 0 || (int)(key->wret) < 0)) {
  73                 printf("err stackid %d %d\n", key->tret, key->wret);
  74         }
  75 }
  76
  77 static void print_stacks(int fd)
  78 {
  79         struct key_t key = {}, next_key;
  80         __u64 value;
  81
  82         while (bpf_map_get_next_key(fd, &key, &next_key) == 0) {
  83                 bpf_map_lookup_elem(fd, &next_key, &value);
  84                 print_stack(&next_key, value);
  85                 key = next_key;
  86         }
  87 }
  88
  89 static void int_exit(int sig)
  90 {
  91         print_stacks(map_fd[0]);
  92         exit(0);
  93 }
  94
  95 int main(int argc, char **argv)
  96 {
  97         struct bpf_object *obj = NULL;
  98         struct bpf_link *links[2];
  99         struct bpf_program *prog;
 100         int delay = 1, i = 0;
 101         char filename[256];
 102
 103         if (load_kallsyms()) {
 104                 printf("failed to process /proc/kallsyms\n");
 105                 return 2;
 106         }
 107
 108         snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
 109         obj = bpf_object__open_file(filename, NULL);
 110         if (libbpf_get_error(obj)) {
 111                 fprintf(stderr, "ERROR: opening BPF object file failed\n");
 112                 obj = NULL;
 113                 goto cleanup;
 114         }
 115
 116         /* load BPF program */
 117         if (bpf_object__load(obj)) {
 118                 fprintf(stderr, "ERROR: loading BPF object file failed\n");
 119                 goto cleanup;
 120         }
 121
 122         map_fd[0] = bpf_object__find_map_fd_by_name(obj, "counts");
 123         map_fd[1] = bpf_object__find_map_fd_by_name(obj, "stackmap");
 124         if (map_fd[0] < 0 || map_fd[1] < 0) {
 125                 fprintf(stderr, "ERROR: finding a map in obj file failed\n");
 126                 goto cleanup;
 127         }
 128
 129         signal(SIGINT, int_exit);
 130         signal(SIGTERM, int_exit);
 131
 132         bpf_object__for_each_program(prog, obj) {
 133                 links[i] = bpf_program__attach(prog);
 134                 if (libbpf_get_error(links[i])) {
 135                         fprintf(stderr, "ERROR: bpf_program__attach failed\n");
 136                         links[i] = NULL;
 137                         goto cleanup;
 138                 }
 139                 i++;
 140         }
 141
 142         if (argc > 1)
 143                 delay = atoi(argv[1]);
 144         sleep(delay);
 145         print_stacks(map_fd[0]);
 146
 147 cleanup:
 148         for (i--; i >= 0; i--)
 149                 bpf_link__destroy(links[i]);
 150
 151         bpf_object__close(obj);
 152         return 0;
 153 }