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 <sys/resource.h>
  12 #include <bpf/libbpf.h>
  13 #include <bpf/bpf.h>
  14 #include "trace_helpers.h"
  15
  16 #define PRINT_RAW_ADDR 0
  17
  18 /* counts, stackmap */
  19 static int map_fd[2];
  20
  21 static void print_ksym(__u64 addr)
  22 {
  23         struct ksym *sym;
  24
  25         if (!addr)
  26                 return;
  27         sym = ksym_search(addr);
  28         if (!sym) {
  29                 printf("ksym not found. Is kallsyms loaded?\n");
  30                 return;
  31         }
  32
  33         if (PRINT_RAW_ADDR)
  34                 printf("%s/%llx;", sym->name, addr);
  35         else
  36                 printf("%s;", sym->name);
  37 }
  38
  39 #define TASK_COMM_LEN 16
  40
  41 struct key_t {
  42         char waker[TASK_COMM_LEN];
  43         char target[TASK_COMM_LEN];
  44         __u32 wret;
  45         __u32 tret;
  46 };
  47
  48 static void print_stack(struct key_t *key, __u64 count)
  49 {
  50         __u64 ip[PERF_MAX_STACK_DEPTH] = {};
  51         static bool warned;
  52         int i;
  53
  54         printf("%s;", key->target);
  55         if (bpf_map_lookup_elem(map_fd[1], &key->tret, ip) != 0) {
  56                 printf("---;");
  57         } else {
  58                 for (i = PERF_MAX_STACK_DEPTH - 1; i >= 0; i--)
  59                         print_ksym(ip[i]);
  60         }
  61         printf("-;");
  62         if (bpf_map_lookup_elem(map_fd[1], &key->wret, ip) != 0) {
  63                 printf("---;");
  64         } else {
  65                 for (i = 0; i < PERF_MAX_STACK_DEPTH; i++)
  66                         print_ksym(ip[i]);
  67         }
  68         printf(";%s %lld\n", key->waker, count);
  69
  70         if ((key->tret == -EEXIST || key->wret == -EEXIST) && !warned) {
  71                 printf("stackmap collisions seen. Consider increasing size\n");
  72                 warned = true;
  73         } else if (((int)(key->tret) < 0 || (int)(key->wret) < 0)) {
  74                 printf("err stackid %d %d\n", key->tret, key->wret);
  75         }
  76 }
  77
  78 static void print_stacks(int fd)
  79 {
  80         struct key_t key = {}, next_key;
  81         __u64 value;
  82
  83         while (bpf_map_get_next_key(fd, &key, &next_key) == 0) {
  84                 bpf_map_lookup_elem(fd, &next_key, &value);
  85                 print_stack(&next_key, value);
  86                 key = next_key;
  87         }
  88 }
  89
  90 static void int_exit(int sig)
  91 {
  92         print_stacks(map_fd[0]);
  93         exit(0);
  94 }
  95
  96 int main(int argc, char **argv)
  97 {
  98         struct bpf_object *obj = NULL;
  99         struct bpf_link *links[2];
 100         struct bpf_program *prog;
 101         int delay = 1, i = 0;
 102         char filename[256];
 103
 104         if (load_kallsyms()) {
 105                 printf("failed to process /proc/kallsyms\n");
 106                 return 2;
 107         }
 108
 109         snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
 110         obj = bpf_object__open_file(filename, NULL);
 111         if (libbpf_get_error(obj)) {
 112                 fprintf(stderr, "ERROR: opening BPF object file failed\n");
 113                 obj = NULL;
 114                 goto cleanup;
 115         }
 116
 117         /* load BPF program */
 118         if (bpf_object__load(obj)) {
 119                 fprintf(stderr, "ERROR: loading BPF object file failed\n");
 120                 goto cleanup;
 121         }
 122
 123         map_fd[0] = bpf_object__find_map_fd_by_name(obj, "counts");
 124         map_fd[1] = bpf_object__find_map_fd_by_name(obj, "stackmap");
 125         if (map_fd[0] < 0 || map_fd[1] < 0) {
 126                 fprintf(stderr, "ERROR: finding a map in obj file failed\n");
 127                 goto cleanup;
 128         }
 129
 130         signal(SIGINT, int_exit);
 131         signal(SIGTERM, int_exit);
 132
 133         bpf_object__for_each_program(prog, obj) {
 134                 links[i] = bpf_program__attach(prog);
 135                 if (libbpf_get_error(links[i])) {
 136                         fprintf(stderr, "ERROR: bpf_program__attach failed\n");
 137                         links[i] = NULL;
 138                         goto cleanup;
 139                 }
 140                 i++;
 141         }
 142
 143         if (argc > 1)
 144                 delay = atoi(argv[1]);
 145         sleep(delay);
 146         print_stacks(map_fd[0]);
 147
 148 cleanup:
 149         for (i--; i >= 0; i--)
 150                 bpf_link__destroy(links[i]);
 151
 152         bpf_object__close(obj);
 153         return 0;
 154 }