1 /* 2 * Common eBPF ELF object loading 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 #ifndef __BPF_LIBBPF_H 22 #define __BPF_LIBBPF_H 23 24 #include <stdio.h> 25 #include <stdbool.h> 26 #include <linux/err.h> 27 #include <sys/types.h> // for size_t 28 29 enum libbpf_errno { 30 __LIBBPF_ERRNO__START = 4000, 31 32 /* Something wrong in libelf */ 33 LIBBPF_ERRNO__LIBELF = __LIBBPF_ERRNO__START, 34 LIBBPF_ERRNO__FORMAT, /* BPF object format invalid */ 35 LIBBPF_ERRNO__KVERSION, /* Incorrect or no 'version' section */ 36 LIBBPF_ERRNO__ENDIAN, /* Endian mismatch */ 37 LIBBPF_ERRNO__INTERNAL, /* Internal error in libbpf */ 38 LIBBPF_ERRNO__RELOC, /* Relocation failed */ 39 LIBBPF_ERRNO__LOAD, /* Load program failure for unknown reason */ 40 LIBBPF_ERRNO__VERIFY, /* Kernel verifier blocks program loading */ 41 LIBBPF_ERRNO__PROG2BIG, /* Program too big */ 42 LIBBPF_ERRNO__KVER, /* Incorrect kernel version */ 43 LIBBPF_ERRNO__PROGTYPE, /* Kernel doesn't support this program type */ 44 __LIBBPF_ERRNO__END, 45 }; 46 47 int libbpf_strerror(int err, char *buf, size_t size); 48 49 /* 50 * In include/linux/compiler-gcc.h, __printf is defined. However 51 * it should be better if libbpf.h doesn't depend on Linux header file. 52 * So instead of __printf, here we use gcc attribute directly. 53 */ 54 typedef int (*libbpf_print_fn_t)(const char *, ...) 55 __attribute__((format(printf, 1, 2))); 56 57 void libbpf_set_print(libbpf_print_fn_t warn, 58 libbpf_print_fn_t info, 59 libbpf_print_fn_t debug); 60 61 /* Hide internal to user */ 62 struct bpf_object; 63 64 struct bpf_object *bpf_object__open(const char *path); 65 struct bpf_object *bpf_object__open_buffer(void *obj_buf, 66 size_t obj_buf_sz, 67 const char *name); 68 void bpf_object__close(struct bpf_object *object); 69 70 /* Load/unload object into/from kernel */ 71 int bpf_object__load(struct bpf_object *obj); 72 int bpf_object__unload(struct bpf_object *obj); 73 const char *bpf_object__name(struct bpf_object *obj); 74 unsigned int bpf_object__kversion(struct bpf_object *obj); 75 76 struct bpf_object *bpf_object__next(struct bpf_object *prev); 77 #define bpf_object__for_each_safe(pos, tmp) \ 78 for ((pos) = bpf_object__next(NULL), \ 79 (tmp) = bpf_object__next(pos); \ 80 (pos) != NULL; \ 81 (pos) = (tmp), (tmp) = bpf_object__next(tmp)) 82 83 typedef void (*bpf_object_clear_priv_t)(struct bpf_object *, void *); 84 int bpf_object__set_priv(struct bpf_object *obj, void *priv, 85 bpf_object_clear_priv_t clear_priv); 86 void *bpf_object__priv(struct bpf_object *prog); 87 88 /* Accessors of bpf_program. */ 89 struct bpf_program; 90 struct bpf_program *bpf_program__next(struct bpf_program *prog, 91 struct bpf_object *obj); 92 93 #define bpf_object__for_each_program(pos, obj) \ 94 for ((pos) = bpf_program__next(NULL, (obj)); \ 95 (pos) != NULL; \ 96 (pos) = bpf_program__next((pos), (obj))) 97 98 typedef void (*bpf_program_clear_priv_t)(struct bpf_program *, 99 void *); 100 101 int bpf_program__set_priv(struct bpf_program *prog, void *priv, 102 bpf_program_clear_priv_t clear_priv); 103 104 void *bpf_program__priv(struct bpf_program *prog); 105 106 const char *bpf_program__title(struct bpf_program *prog, bool needs_copy); 107 108 int bpf_program__fd(struct bpf_program *prog); 109 110 struct bpf_insn; 111 112 /* 113 * Libbpf allows callers to adjust BPF programs before being loaded 114 * into kernel. One program in an object file can be transform into 115 * multiple variants to be attached to different code. 116 * 117 * bpf_program_prep_t, bpf_program__set_prep and bpf_program__nth_fd 118 * are APIs for this propose. 119 * 120 * - bpf_program_prep_t: 121 * It defines 'preprocessor', which is a caller defined function 122 * passed to libbpf through bpf_program__set_prep(), and will be 123 * called before program is loaded. The processor should adjust 124 * the program one time for each instances according to the number 125 * passed to it. 126 * 127 * - bpf_program__set_prep: 128 * Attachs a preprocessor to a BPF program. The number of instances 129 * whould be created is also passed through this function. 130 * 131 * - bpf_program__nth_fd: 132 * After the program is loaded, get resuling fds from bpf program for 133 * each instances. 134 * 135 * If bpf_program__set_prep() is not used, the program whould be loaded 136 * without adjustment during bpf_object__load(). The program has only 137 * one instance. In this case bpf_program__fd(prog) is equal to 138 * bpf_program__nth_fd(prog, 0). 139 */ 140 141 struct bpf_prog_prep_result { 142 /* 143 * If not NULL, load new instruction array. 144 * If set to NULL, don't load this instance. 145 */ 146 struct bpf_insn *new_insn_ptr; 147 int new_insn_cnt; 148 149 /* If not NULL, result fd is set to it */ 150 int *pfd; 151 }; 152 153 /* 154 * Parameters of bpf_program_prep_t: 155 * - prog: The bpf_program being loaded. 156 * - n: Index of instance being generated. 157 * - insns: BPF instructions array. 158 * - insns_cnt:Number of instructions in insns. 159 * - res: Output parameter, result of transformation. 160 * 161 * Return value: 162 * - Zero: pre-processing success. 163 * - Non-zero: pre-processing, stop loading. 164 */ 165 typedef int (*bpf_program_prep_t)(struct bpf_program *prog, int n, 166 struct bpf_insn *insns, int insns_cnt, 167 struct bpf_prog_prep_result *res); 168 169 int bpf_program__set_prep(struct bpf_program *prog, int nr_instance, 170 bpf_program_prep_t prep); 171 172 int bpf_program__nth_fd(struct bpf_program *prog, int n); 173 174 /* 175 * Adjust type of bpf program. Default is kprobe. 176 */ 177 int bpf_program__set_tracepoint(struct bpf_program *prog); 178 int bpf_program__set_kprobe(struct bpf_program *prog); 179 180 bool bpf_program__is_tracepoint(struct bpf_program *prog); 181 bool bpf_program__is_kprobe(struct bpf_program *prog); 182 183 /* 184 * We don't need __attribute__((packed)) now since it is 185 * unnecessary for 'bpf_map_def' because they are all aligned. 186 * In addition, using it will trigger -Wpacked warning message, 187 * and will be treated as an error due to -Werror. 188 */ 189 struct bpf_map_def { 190 unsigned int type; 191 unsigned int key_size; 192 unsigned int value_size; 193 unsigned int max_entries; 194 }; 195 196 /* 197 * There is another 'struct bpf_map' in include/linux/map.h. However, 198 * it is not a uapi header so no need to consider name clash. 199 */ 200 struct bpf_map; 201 struct bpf_map * 202 bpf_object__find_map_by_name(struct bpf_object *obj, const char *name); 203 204 /* 205 * Get bpf_map through the offset of corresponding struct bpf_map_def 206 * in the bpf object file. 207 */ 208 struct bpf_map * 209 bpf_object__find_map_by_offset(struct bpf_object *obj, size_t offset); 210 211 struct bpf_map * 212 bpf_map__next(struct bpf_map *map, struct bpf_object *obj); 213 #define bpf_map__for_each(pos, obj) \ 214 for ((pos) = bpf_map__next(NULL, (obj)); \ 215 (pos) != NULL; \ 216 (pos) = bpf_map__next((pos), (obj))) 217 218 int bpf_map__fd(struct bpf_map *map); 219 const struct bpf_map_def *bpf_map__def(struct bpf_map *map); 220 const char *bpf_map__name(struct bpf_map *map); 221 222 typedef void (*bpf_map_clear_priv_t)(struct bpf_map *, void *); 223 int bpf_map__set_priv(struct bpf_map *map, void *priv, 224 bpf_map_clear_priv_t clear_priv); 225 void *bpf_map__priv(struct bpf_map *map); 226 227 #endif 228