samples/bpf/syscall_tp_user.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /* Copyright (c) 2017 Facebook
   3  */
   4 #include <stdio.h>
   5 #include <unistd.h>
   6 #include <fcntl.h>
   7 #include <stdlib.h>
   8 #include <string.h>
   9 #include <linux/perf_event.h>
  10 #include <errno.h>
  11 #include <bpf/libbpf.h>
  12 #include <bpf/bpf.h>
  13
  14 /* This program verifies bpf attachment to tracepoint sys_enter_* and sys_exit_*.
  15  * This requires kernel CONFIG_FTRACE_SYSCALLS to be set.
  16  */
  17
  18 static void usage(const char *cmd)
  19 {
  20         printf("USAGE: %s [-i num_progs] [-h]\n", cmd);
  21         printf("       -i num_progs      # number of progs of the test\n");
  22         printf("       -h                # help\n");
  23 }
  24
  25 static void verify_map(int map_id)
  26 {
  27         __u32 key = 0;
  28         __u32 val;
  29
  30         if (bpf_map_lookup_elem(map_id, &key, &val) != 0) {
  31                 fprintf(stderr, "map_lookup failed: %s\n", strerror(errno));
  32                 return;
  33         }
  34         if (val == 0) {
  35                 fprintf(stderr, "failed: map #%d returns value 0\n", map_id);
  36                 return;
  37         }
  38
  39         printf("verify map:%d val: %d\n", map_id, val);
  40
  41         val = 0;
  42         if (bpf_map_update_elem(map_id, &key, &val, BPF_ANY) != 0) {
  43                 fprintf(stderr, "map_update failed: %s\n", strerror(errno));
  44                 return;
  45         }
  46 }
  47
  48 static int test(char *filename, int num_progs)
  49 {
  50         int map0_fds[num_progs], map1_fds[num_progs], fd, i, j = 0;
  51         struct bpf_link *links[num_progs * 4];
  52         struct bpf_object *objs[num_progs];
  53         struct bpf_program *prog;
  54
  55         for (i = 0; i < num_progs; i++) {
  56                 objs[i] = bpf_object__open_file(filename, NULL);
  57                 if (libbpf_get_error(objs[i])) {
  58                         fprintf(stderr, "opening BPF object file failed\n");
  59                         objs[i] = NULL;
  60                         goto cleanup;
  61                 }
  62
  63                 /* load BPF program */
  64                 if (bpf_object__load(objs[i])) {
  65                         fprintf(stderr, "loading BPF object file failed\n");
  66                         goto cleanup;
  67                 }
  68
  69                 map0_fds[i] = bpf_object__find_map_fd_by_name(objs[i],
  70                                                               "enter_open_map");
  71                 map1_fds[i] = bpf_object__find_map_fd_by_name(objs[i],
  72                                                               "exit_open_map");
  73                 if (map0_fds[i] < 0 || map1_fds[i] < 0) {
  74                         fprintf(stderr, "finding a map in obj file failed\n");
  75                         goto cleanup;
  76                 }
  77
  78                 bpf_object__for_each_program(prog, objs[i]) {
  79                         links[j] = bpf_program__attach(prog);
  80                         if (libbpf_get_error(links[j])) {
  81                                 fprintf(stderr, "bpf_program__attach failed\n");
  82                                 links[j] = NULL;
  83                                 goto cleanup;
  84                         }
  85                         j++;
  86                 }
  87                 printf("prog #%d: map ids %d %d\n", i, map0_fds[i], map1_fds[i]);
  88         }
  89
  90         /* current load_bpf_file has perf_event_open default pid = -1
  91          * and cpu = 0, which permits attached bpf execution on
  92          * all cpus for all pid's. bpf program execution ignores
  93          * cpu affinity.
  94          */
  95         /* trigger some "open" operations */
  96         fd = open(filename, O_RDONLY);
  97         if (fd < 0) {
  98                 fprintf(stderr, "open failed: %s\n", strerror(errno));
  99                 return 1;
 100         }
 101         close(fd);
 102
 103         /* verify the map */
 104         for (i = 0; i < num_progs; i++) {
 105                 verify_map(map0_fds[i]);
 106                 verify_map(map1_fds[i]);
 107         }
 108
 109 cleanup:
 110         for (j--; j >= 0; j--)
 111                 bpf_link__destroy(links[j]);
 112
 113         for (i--; i >= 0; i--)
 114                 bpf_object__close(objs[i]);
 115         return 0;
 116 }
 117
 118 int main(int argc, char **argv)
 119 {
 120         int opt, num_progs = 1;
 121         char filename[256];
 122
 123         while ((opt = getopt(argc, argv, "i:h")) != -1) {
 124                 switch (opt) {
 125                 case 'i':
 126                         num_progs = atoi(optarg);
 127                         break;
 128                 case 'h':
 129                 default:
 130                         usage(argv[0]);
 131                         return 0;
 132                 }
 133         }
 134
 135         snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
 136
 137         return test(filename, num_progs);
 138 }