root/samples/bpf/syscall_tp_user.c

DEFINITIONS

1. usage
2. verify_map
3. test
4. main

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