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
   9#include <stdlib.h>
  10#include <memory.h>
  11#include <unistd.h>
  12#include <asm/unistd.h>
  13#include <linux/bpf.h>
  14#include "bpf.h"
  15
  16/*
  17 * When building perf, unistd.h is overrided. __NR_bpf is
  18 * required to be defined explicitly.
  19 */
  20#ifndef __NR_bpf
  21# if defined(__i386__)
  22#  define __NR_bpf 357
  23# elif defined(__x86_64__)
  24#  define __NR_bpf 321
  25# elif defined(__aarch64__)
  26#  define __NR_bpf 280
  27# else
  28#  error __NR_bpf not defined. libbpf does not support your arch.
  29# endif
  30#endif
  31
  32static __u64 ptr_to_u64(void *ptr)
  33{
  34        return (__u64) (unsigned long) ptr;
  35}
  36
  37static int sys_bpf(enum bpf_cmd cmd, union bpf_attr *attr,
  38                   unsigned int size)
  39{
  40        return syscall(__NR_bpf, cmd, attr, size);
  41}
  42
  43int bpf_create_map(enum bpf_map_type map_type, int key_size,
  44                   int value_size, int max_entries)
  45{
  46        union bpf_attr attr;
  47
  48        memset(&attr, '\0', sizeof(attr));
  49
  50        attr.map_type = map_type;
  51        attr.key_size = key_size;
  52        attr.value_size = value_size;
  53        attr.max_entries = max_entries;
  54
  55        return sys_bpf(BPF_MAP_CREATE, &attr, sizeof(attr));
  56}
  57
  58int bpf_load_program(enum bpf_prog_type type, struct bpf_insn *insns,
  59                     size_t insns_cnt, char *license,
  60                     u32 kern_version, char *log_buf, size_t log_buf_sz)
  61{
  62        int fd;
  63        union bpf_attr attr;
  64
  65        bzero(&attr, sizeof(attr));
  66        attr.prog_type = type;
  67        attr.insn_cnt = (__u32)insns_cnt;
  68        attr.insns = ptr_to_u64(insns);
  69        attr.license = ptr_to_u64(license);
  70        attr.log_buf = ptr_to_u64(NULL);
  71        attr.log_size = 0;
  72        attr.log_level = 0;
  73        attr.kern_version = kern_version;
  74
  75        fd = sys_bpf(BPF_PROG_LOAD, &attr, sizeof(attr));
  76        if (fd >= 0 || !log_buf || !log_buf_sz)
  77                return fd;
  78
  79        /* Try again with log */
  80        attr.log_buf = ptr_to_u64(log_buf);
  81        attr.log_size = log_buf_sz;
  82        attr.log_level = 1;
  83        log_buf[0] = 0;
  84        return sys_bpf(BPF_PROG_LOAD, &attr, sizeof(attr));
  85}
  86
  87int bpf_map_update_elem(int fd, void *key, void *value,
  88                        u64 flags)
  89{
  90        union bpf_attr attr;
  91
  92        bzero(&attr, sizeof(attr));
  93        attr.map_fd = fd;
  94        attr.key = ptr_to_u64(key);
  95        attr.value = ptr_to_u64(value);
  96        attr.flags = flags;
  97
  98        return sys_bpf(BPF_MAP_UPDATE_ELEM, &attr, sizeof(attr));
  99}
 100