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, __u32 map_flags)
  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         attr.map_flags = map_flags;
  68
  69         return sys_bpf(BPF_MAP_CREATE, &attr, sizeof(attr));
  70 }
  71
  72 int bpf_load_program(enum bpf_prog_type type, struct bpf_insn *insns,
  73                      size_t insns_cnt, char *license,
  74                      __u32 kern_version, char *log_buf, size_t log_buf_sz)
  75 {
  76         int fd;
  77         union bpf_attr attr;
  78
  79         bzero(&attr, sizeof(attr));
  80         attr.prog_type = type;
  81         attr.insn_cnt = (__u32)insns_cnt;
  82         attr.insns = ptr_to_u64(insns);
  83         attr.license = ptr_to_u64(license);
  84         attr.log_buf = ptr_to_u64(NULL);
  85         attr.log_size = 0;
  86         attr.log_level = 0;
  87         attr.kern_version = kern_version;
  88
  89         fd = sys_bpf(BPF_PROG_LOAD, &attr, sizeof(attr));
  90         if (fd >= 0 || !log_buf || !log_buf_sz)
  91                 return fd;
  92
  93         /* Try again with log */
  94         attr.log_buf = ptr_to_u64(log_buf);
  95         attr.log_size = log_buf_sz;
  96         attr.log_level = 1;
  97         log_buf[0] = 0;
  98         return sys_bpf(BPF_PROG_LOAD, &attr, sizeof(attr));
  99 }
 100
 101 int bpf_map_update_elem(int fd, void *key, void *value,
 102                         __u64 flags)
 103 {
 104         union bpf_attr attr;
 105
 106         bzero(&attr, sizeof(attr));
 107         attr.map_fd = fd;
 108         attr.key = ptr_to_u64(key);
 109         attr.value = ptr_to_u64(value);
 110         attr.flags = flags;
 111
 112         return sys_bpf(BPF_MAP_UPDATE_ELEM, &attr, sizeof(attr));
 113 }
 114
 115 int bpf_map_lookup_elem(int fd, void *key, void *value)
 116 {
 117         union bpf_attr attr;
 118
 119         bzero(&attr, sizeof(attr));
 120         attr.map_fd = fd;
 121         attr.key = ptr_to_u64(key);
 122         attr.value = ptr_to_u64(value);
 123
 124         return sys_bpf(BPF_MAP_LOOKUP_ELEM, &attr, sizeof(attr));
 125 }
 126
 127 int bpf_map_delete_elem(int fd, void *key)
 128 {
 129         union bpf_attr attr;
 130
 131         bzero(&attr, sizeof(attr));
 132         attr.map_fd = fd;
 133         attr.key = ptr_to_u64(key);
 134
 135         return sys_bpf(BPF_MAP_DELETE_ELEM, &attr, sizeof(attr));
 136 }
 137
 138 int bpf_map_get_next_key(int fd, void *key, void *next_key)
 139 {
 140         union bpf_attr attr;
 141
 142         bzero(&attr, sizeof(attr));
 143         attr.map_fd = fd;
 144         attr.key = ptr_to_u64(key);
 145         attr.next_key = ptr_to_u64(next_key);
 146
 147         return sys_bpf(BPF_MAP_GET_NEXT_KEY, &attr, sizeof(attr));
 148 }
 149
 150 int bpf_obj_pin(int fd, const char *pathname)
 151 {
 152         union bpf_attr attr;
 153
 154         bzero(&attr, sizeof(attr));
 155         attr.pathname = ptr_to_u64((void *)pathname);
 156         attr.bpf_fd = fd;
 157
 158         return sys_bpf(BPF_OBJ_PIN, &attr, sizeof(attr));
 159 }
 160
 161 int bpf_obj_get(const char *pathname)
 162 {
 163         union bpf_attr attr;
 164
 165         bzero(&attr, sizeof(attr));
 166         attr.pathname = ptr_to_u64((void *)pathname);
 167
 168         return sys_bpf(BPF_OBJ_GET, &attr, sizeof(attr));
 169 }
 170
 171 int bpf_prog_attach(int prog_fd, int target_fd, enum bpf_attach_type type)
 172 {
 173         union bpf_attr attr;
 174
 175         bzero(&attr, sizeof(attr));
 176         attr.target_fd     = target_fd;
 177         attr.attach_bpf_fd = prog_fd;
 178         attr.attach_type   = type;
 179
 180         return sys_bpf(BPF_PROG_ATTACH, &attr, sizeof(attr));
 181 }
 182
 183 int bpf_prog_detach(int target_fd, enum bpf_attach_type type)
 184 {
 185         union bpf_attr attr;
 186
 187         bzero(&attr, sizeof(attr));
 188         attr.target_fd   = target_fd;
 189         attr.attach_type = type;
 190
 191         return sys_bpf(BPF_PROG_DETACH, &attr, sizeof(attr));
 192 }