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
  45 static __u64 ptr_to_u64(void *ptr)
  46 {
  47         return (__u64) (unsigned long) ptr;
  48 }
  49
  50 static 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
  56 int 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
  71 int 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
 100 int 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 }