samples/bpf/syscall_tp_user.c

   1 /* Copyright (c) 2017 Facebook
   2  *
   3  * This program is free software; you can redistribute it and/or
   4  * modify it under the terms of version 2 of the GNU General Public
   5  * License as published by the Free Software Foundation.
   6  */
   7 #include <stdio.h>
   8 #include <unistd.h>
   9 #include <fcntl.h>
  10 #include <stdlib.h>
  11 #include <signal.h>
  12 #include <linux/bpf.h>
  13 #include <string.h>
  14 #include <linux/perf_event.h>
  15 #include <errno.h>
  16 #include <assert.h>
  17 #include <stdbool.h>
  18 #include <sys/resource.h>
  19 #include "libbpf.h"
  20 #include "bpf_load.h"
  21
  22 /* This program verifies bpf attachment to tracepoint sys_enter_* and sys_exit_*.
  23  * This requires kernel CONFIG_FTRACE_SYSCALLS to be set.
  24  */
  25
  26 static void usage(const char *cmd)
  27 {
  28         printf("USAGE: %s [-i num_progs] [-h]\n", cmd);
  29         printf("       -i num_progs      # number of progs of the test\n");
  30         printf("       -h                # help\n");
  31 }
  32
  33 static void verify_map(int map_id)
  34 {
  35         __u32 key = 0;
  36         __u32 val;
  37
  38         if (bpf_map_lookup_elem(map_id, &key, &val) != 0) {
  39                 fprintf(stderr, "map_lookup failed: %s\n", strerror(errno));
  40                 return;
  41         }
  42         if (val == 0) {
  43                 fprintf(stderr, "failed: map #%d returns value 0\n", map_id);
  44                 return;
  45         }
  46         val = 0;
  47         if (bpf_map_update_elem(map_id, &key, &val, BPF_ANY) != 0) {
  48                 fprintf(stderr, "map_update failed: %s\n", strerror(errno));
  49                 return;
  50         }
  51 }
  52
  53 static int test(char *filename, int num_progs)
  54 {
  55         int i, fd, map0_fds[num_progs], map1_fds[num_progs];
  56
  57         for (i = 0; i < num_progs; i++) {
  58                 if (load_bpf_file(filename)) {
  59                         fprintf(stderr, "%s", bpf_log_buf);
  60                         return 1;
  61                 }
  62                 printf("prog #%d: map ids %d %d\n", i, map_fd[0], map_fd[1]);
  63                 map0_fds[i] = map_fd[0];
  64                 map1_fds[i] = map_fd[1];
  65         }
  66
  67         /* current load_bpf_file has perf_event_open default pid = -1
  68          * and cpu = 0, which permits attached bpf execution on
  69          * all cpus for all pid's. bpf program execution ignores
  70          * cpu affinity.
  71          */
  72         /* trigger some "open" operations */
  73         fd = open(filename, O_RDONLY);
  74         if (fd < 0) {
  75                 fprintf(stderr, "open failed: %s\n", strerror(errno));
  76                 return 1;
  77         }
  78         close(fd);
  79
  80         /* verify the map */
  81         for (i = 0; i < num_progs; i++) {
  82                 verify_map(map0_fds[i]);
  83                 verify_map(map1_fds[i]);
  84         }
  85
  86         return 0;
  87 }
  88
  89 int main(int argc, char **argv)
  90 {
  91         struct rlimit r = {RLIM_INFINITY, RLIM_INFINITY};
  92         int opt, num_progs = 1;
  93         char filename[256];
  94
  95         while ((opt = getopt(argc, argv, "i:h")) != -1) {
  96                 switch (opt) {
  97                 case 'i':
  98                         num_progs = atoi(optarg);
  99                         break;
 100                 case 'h':
 101                 default:
 102                         usage(argv[0]);
 103                         return 0;
 104                 }
 105         }
 106
 107         setrlimit(RLIMIT_MEMLOCK, &r);
 108         snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
 109
 110         return test(filename, num_progs);
 111 }