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