samples/bpf/libbpf.c

   1 /* eBPF mini library */
   2 #include <stdlib.h>
   3 #include <stdio.h>
   4 #include <linux/unistd.h>
   5 #include <unistd.h>
   6 #include <string.h>
   7 #include <linux/netlink.h>
   8 #include <linux/bpf.h>
   9 #include <errno.h>
  10 #include "libbpf.h"
  11
  12 static __u64 ptr_to_u64(void *ptr)
  13 {
  14         return (__u64) (unsigned long) ptr;
  15 }
  16
  17 int bpf_create_map(enum bpf_map_type map_type, int key_size, int value_size,
  18                    int max_entries)
  19 {
  20         union bpf_attr attr = {
  21                 .map_type = map_type,
  22                 .key_size = key_size,
  23                 .value_size = value_size,
  24                 .max_entries = max_entries
  25         };
  26
  27         return syscall(__NR_bpf, BPF_MAP_CREATE, &attr, sizeof(attr));
  28 }
  29
  30 int bpf_update_elem(int fd, void *key, void *value, unsigned long long flags)
  31 {
  32         union bpf_attr attr = {
  33                 .map_fd = fd,
  34                 .key = ptr_to_u64(key),
  35                 .value = ptr_to_u64(value),
  36                 .flags = flags,
  37         };
  38
  39         return syscall(__NR_bpf, BPF_MAP_UPDATE_ELEM, &attr, sizeof(attr));
  40 }
  41
  42 int bpf_lookup_elem(int fd, void *key, void *value)
  43 {
  44         union bpf_attr attr = {
  45                 .map_fd = fd,
  46                 .key = ptr_to_u64(key),
  47                 .value = ptr_to_u64(value),
  48         };
  49
  50         return syscall(__NR_bpf, BPF_MAP_LOOKUP_ELEM, &attr, sizeof(attr));
  51 }
  52
  53 int bpf_delete_elem(int fd, void *key)
  54 {
  55         union bpf_attr attr = {
  56                 .map_fd = fd,
  57                 .key = ptr_to_u64(key),
  58         };
  59
  60         return syscall(__NR_bpf, BPF_MAP_DELETE_ELEM, &attr, sizeof(attr));
  61 }
  62
  63 int bpf_get_next_key(int fd, void *key, void *next_key)
  64 {
  65         union bpf_attr attr = {
  66                 .map_fd = fd,
  67                 .key = ptr_to_u64(key),
  68                 .next_key = ptr_to_u64(next_key),
  69         };
  70
  71         return syscall(__NR_bpf, BPF_MAP_GET_NEXT_KEY, &attr, sizeof(attr));
  72 }
  73
  74 #define ROUND_UP(x, n) (((x) + (n) - 1u) & ~((n) - 1u))
  75
  76 char bpf_log_buf[LOG_BUF_SIZE];
  77
  78 int bpf_prog_load(enum bpf_prog_type prog_type,
  79                   const struct bpf_insn *insns, int prog_len,
  80                   const char *license)
  81 {
  82         union bpf_attr attr = {
  83                 .prog_type = prog_type,
  84                 .insns = ptr_to_u64((void *) insns),
  85                 .insn_cnt = prog_len / sizeof(struct bpf_insn),
  86                 .license = ptr_to_u64((void *) license),
  87                 .log_buf = ptr_to_u64(bpf_log_buf),
  88                 .log_size = LOG_BUF_SIZE,
  89                 .log_level = 1,
  90         };
  91
  92         bpf_log_buf[0] = 0;
  93
  94         return syscall(__NR_bpf, BPF_PROG_LOAD, &attr, sizeof(attr));
  95 }