LXR linux/samples/bpf/syscall_tp

   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
  26static 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
  33static 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
  53static 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
  89int 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}
 112