samples/bpf/spintest_user.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 #include <stdio.h>
   3 #include <unistd.h>
   4 #include <string.h>
   5 #include <assert.h>
   6 #include <sys/resource.h>
   7 #include <bpf/libbpf.h>
   8 #include <bpf/bpf.h>
   9 #include "trace_helpers.h"
  10
  11 int main(int ac, char **argv)
  12 {
  13         char filename[256], symbol[256];
  14         struct bpf_object *obj = NULL;
  15         struct bpf_link *links[20];
  16         long key, next_key, value;
  17         struct bpf_program *prog;
  18         int map_fd, i, j = 0;
  19         const char *section;
  20         struct ksym *sym;
  21
  22         if (load_kallsyms()) {
  23                 printf("failed to process /proc/kallsyms\n");
  24                 return 2;
  25         }
  26
  27         snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
  28         obj = bpf_object__open_file(filename, NULL);
  29         if (libbpf_get_error(obj)) {
  30                 fprintf(stderr, "ERROR: opening BPF object file failed\n");
  31                 obj = NULL;
  32                 goto cleanup;
  33         }
  34
  35         /* load BPF program */
  36         if (bpf_object__load(obj)) {
  37                 fprintf(stderr, "ERROR: loading BPF object file failed\n");
  38                 goto cleanup;
  39         }
  40
  41         map_fd = bpf_object__find_map_fd_by_name(obj, "my_map");
  42         if (map_fd < 0) {
  43                 fprintf(stderr, "ERROR: finding a map in obj file failed\n");
  44                 goto cleanup;
  45         }
  46
  47         bpf_object__for_each_program(prog, obj) {
  48                 section = bpf_program__section_name(prog);
  49                 if (sscanf(section, "kprobe/%s", symbol) != 1)
  50                         continue;
  51
  52                 /* Attach prog only when symbol exists */
  53                 if (ksym_get_addr(symbol)) {
  54                         links[j] = bpf_program__attach(prog);
  55                         if (libbpf_get_error(links[j])) {
  56                                 fprintf(stderr, "bpf_program__attach failed\n");
  57                                 links[j] = NULL;
  58                                 goto cleanup;
  59                         }
  60                         j++;
  61                 }
  62         }
  63
  64         for (i = 0; i < 5; i++) {
  65                 key = 0;
  66                 printf("kprobing funcs:");
  67                 while (bpf_map_get_next_key(map_fd, &key, &next_key) == 0) {
  68                         bpf_map_lookup_elem(map_fd, &next_key, &value);
  69                         assert(next_key == value);
  70                         sym = ksym_search(value);
  71                         key = next_key;
  72                         if (!sym) {
  73                                 printf("ksym not found. Is kallsyms loaded?\n");
  74                                 continue;
  75                         }
  76
  77                         printf(" %s", sym->name);
  78                 }
  79                 if (key)
  80                         printf("\n");
  81                 key = 0;
  82                 while (bpf_map_get_next_key(map_fd, &key, &next_key) == 0)
  83                         bpf_map_delete_elem(map_fd, &next_key);
  84                 sleep(1);
  85         }
  86
  87 cleanup:
  88         for (j--; j >= 0; j--)
  89                 bpf_link__destroy(links[j]);
  90
  91         bpf_object__close(obj);
  92         return 0;
  93 }