LXR linux/samples/bpf/syscall_tp

   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
  23static 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
  30static 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
  50static 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
  86int 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}
 109