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