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