LXR linux/tools/lib/bpf/bpf.c

   1/*
   2 * common eBPF ELF operations.
   3 *
   4 * Copyright (C) 2013-2015 Alexei Starovoitov <ast@kernel.org>
   5 * Copyright (C) 2015 Wang Nan <wangnan0@huawei.com>
   6 * Copyright (C) 2015 Huawei Inc.
   7 *
   8 * This program is free software; you can redistribute it and/or
   9 * modify it under the terms of the GNU Lesser General Public
  10 * License as published by the Free Software Foundation;
  11 * version 2.1 of the License (not later!)
  12 *
  13 * This program is distributed in the hope that it will be useful,
  14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16 * GNU Lesser General Public License for more details.
  17 *
  18 * You should have received a copy of the GNU Lesser General Public
  19 * License along with this program; if not,  see <http://www.gnu.org/licenses>
  20 */
  21
  22#include <stdlib.h>
  23#include <memory.h>
  24#include <unistd.h>
  25#include <asm/unistd.h>
  26#include <linux/bpf.h>
  27#include "bpf.h"
  28
  29/*
  30 * When building perf, unistd.h is overrided. __NR_bpf is
  31 * required to be defined explicitly.
  32 */
  33#ifndef __NR_bpf
  34# if defined(__i386__)
  35#  define __NR_bpf 357
  36# elif defined(__x86_64__)
  37#  define __NR_bpf 321
  38# elif defined(__aarch64__)
  39#  define __NR_bpf 280
  40# else
  41#  error __NR_bpf not defined. libbpf does not support your arch.
  42# endif
  43#endif
  44
  45static __u64 ptr_to_u64(void *ptr)
  46{
  47        return (__u64) (unsigned long) ptr;
  48}
  49
  50static int sys_bpf(enum bpf_cmd cmd, union bpf_attr *attr,
  51                   unsigned int size)
  52{
  53        return syscall(__NR_bpf, cmd, attr, size);
  54}
  55
  56int bpf_create_map(enum bpf_map_type map_type, int key_size,
  57                   int value_size, int max_entries)
  58{
  59        union bpf_attr attr;
  60
  61        memset(&attr, '\0', sizeof(attr));
  62
  63        attr.map_type = map_type;
  64        attr.key_size = key_size;
  65        attr.value_size = value_size;
  66        attr.max_entries = max_entries;
  67
  68        return sys_bpf(BPF_MAP_CREATE, &attr, sizeof(attr));
  69}
  70
  71int bpf_load_program(enum bpf_prog_type type, struct bpf_insn *insns,
  72                     size_t insns_cnt, char *license,
  73                     u32 kern_version, char *log_buf, size_t log_buf_sz)
  74{
  75        int fd;
  76        union bpf_attr attr;
  77
  78        bzero(&attr, sizeof(attr));
  79        attr.prog_type = type;
  80        attr.insn_cnt = (__u32)insns_cnt;
  81        attr.insns = ptr_to_u64(insns);
  82        attr.license = ptr_to_u64(license);
  83        attr.log_buf = ptr_to_u64(NULL);
  84        attr.log_size = 0;
  85        attr.log_level = 0;
  86        attr.kern_version = kern_version;
  87
  88        fd = sys_bpf(BPF_PROG_LOAD, &attr, sizeof(attr));
  89        if (fd >= 0 || !log_buf || !log_buf_sz)
  90                return fd;
  91
  92        /* Try again with log */
  93        attr.log_buf = ptr_to_u64(log_buf);
  94        attr.log_size = log_buf_sz;
  95        attr.log_level = 1;
  96        log_buf[0] = 0;
  97        return sys_bpf(BPF_PROG_LOAD, &attr, sizeof(attr));
  98}
  99
 100int bpf_map_update_elem(int fd, void *key, void *value,
 101                        u64 flags)
 102{
 103        union bpf_attr attr;
 104
 105        bzero(&attr, sizeof(attr));
 106        attr.map_fd = fd;
 107        attr.key = ptr_to_u64(key);
 108        attr.value = ptr_to_u64(value);
 109        attr.flags = flags;
 110
 111        return sys_bpf(BPF_MAP_UPDATE_ELEM, &attr, sizeof(attr));
 112}
 113