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 #ifndef __BPF_LIBBPF_H 9 #define __BPF_LIBBPF_H 10 11 #include <stdio.h> 12 #include <stdbool.h> 13 #include <linux/err.h> 14 15 enum libbpf_errno { 16 __LIBBPF_ERRNO__START = 4000, 17 18 /* Something wrong in libelf */ 19 LIBBPF_ERRNO__LIBELF = __LIBBPF_ERRNO__START, 20 LIBBPF_ERRNO__FORMAT, /* BPF object format invalid */ 21 LIBBPF_ERRNO__KVERSION, /* Incorrect or no 'version' section */ 22 LIBBPF_ERRNO__ENDIAN, /* Endian missmatch */ 23 LIBBPF_ERRNO__INTERNAL, /* Internal error in libbpf */ 24 LIBBPF_ERRNO__RELOC, /* Relocation failed */ 25 LIBBPF_ERRNO__LOAD, /* Load program failure for unknown reason */ 26 LIBBPF_ERRNO__VERIFY, /* Kernel verifier blocks program loading */ 27 LIBBPF_ERRNO__PROG2BIG, /* Program too big */ 28 LIBBPF_ERRNO__KVER, /* Incorrect kernel version */ 29 __LIBBPF_ERRNO__END, 30 }; 31 32 int libbpf_strerror(int err, char *buf, size_t size); 33 34 /* 35 * In include/linux/compiler-gcc.h, __printf is defined. However 36 * it should be better if libbpf.h doesn't depend on Linux header file. 37 * So instead of __printf, here we use gcc attribute directly. 38 */ 39 typedef int (*libbpf_print_fn_t)(const char *, ...) 40 __attribute__((format(printf, 1, 2))); 41 42 void libbpf_set_print(libbpf_print_fn_t warn, 43 libbpf_print_fn_t info, 44 libbpf_print_fn_t debug); 45 46 /* Hide internal to user */ 47 struct bpf_object; 48 49 struct bpf_object *bpf_object__open(const char *path); 50 struct bpf_object *bpf_object__open_buffer(void *obj_buf, 51 size_t obj_buf_sz, 52 const char *name); 53 void bpf_object__close(struct bpf_object *object); 54 55 /* Load/unload object into/from kernel */ 56 int bpf_object__load(struct bpf_object *obj); 57 int bpf_object__unload(struct bpf_object *obj); 58 const char *bpf_object__name(struct bpf_object *obj); 59 unsigned int bpf_object__kversion(struct bpf_object *obj); 60 61 struct bpf_object *bpf_object__next(struct bpf_object *prev); 62 #define bpf_object__for_each_safe(pos, tmp) \ 63 for ((pos) = bpf_object__next(NULL), \ 64 (tmp) = bpf_object__next(pos); \ 65 (pos) != NULL; \ 66 (pos) = (tmp), (tmp) = bpf_object__next(tmp)) 67 68 /* Accessors of bpf_program. */ 69 struct bpf_program; 70 struct bpf_program *bpf_program__next(struct bpf_program *prog, 71 struct bpf_object *obj); 72 73 #define bpf_object__for_each_program(pos, obj) \ 74 for ((pos) = bpf_program__next(NULL, (obj)); \ 75 (pos) != NULL; \ 76 (pos) = bpf_program__next((pos), (obj))) 77 78 typedef void (*bpf_program_clear_priv_t)(struct bpf_program *, 79 void *); 80 81 int bpf_program__set_priv(struct bpf_program *prog, void *priv, 82 bpf_program_clear_priv_t clear_priv); 83 84 void *bpf_program__priv(struct bpf_program *prog); 85 86 const char *bpf_program__title(struct bpf_program *prog, bool needs_copy); 87 88 int bpf_program__fd(struct bpf_program *prog); 89 90 struct bpf_insn; 91 92 /* 93 * Libbpf allows callers to adjust BPF programs before being loaded 94 * into kernel. One program in an object file can be transform into 95 * multiple variants to be attached to different code. 96 * 97 * bpf_program_prep_t, bpf_program__set_prep and bpf_program__nth_fd 98 * are APIs for this propose. 99 * 100 * - bpf_program_prep_t: 101 * It defines 'preprocessor', which is a caller defined function 102 * passed to libbpf through bpf_program__set_prep(), and will be 103 * called before program is loaded. The processor should adjust 104 * the program one time for each instances according to the number 105 * passed to it. 106 * 107 * - bpf_program__set_prep: 108 * Attachs a preprocessor to a BPF program. The number of instances 109 * whould be created is also passed through this function. 110 * 111 * - bpf_program__nth_fd: 112 * After the program is loaded, get resuling fds from bpf program for 113 * each instances. 114 * 115 * If bpf_program__set_prep() is not used, the program whould be loaded 116 * without adjustment during bpf_object__load(). The program has only 117 * one instance. In this case bpf_program__fd(prog) is equal to 118 * bpf_program__nth_fd(prog, 0). 119 */ 120 121 struct bpf_prog_prep_result { 122 /* 123 * If not NULL, load new instruction array. 124 * If set to NULL, don't load this instance. 125 */ 126 struct bpf_insn *new_insn_ptr; 127 int new_insn_cnt; 128 129 /* If not NULL, result fd is set to it */ 130 int *pfd; 131 }; 132 133 /* 134 * Parameters of bpf_program_prep_t: 135 * - prog: The bpf_program being loaded. 136 * - n: Index of instance being generated. 137 * - insns: BPF instructions array. 138 * - insns_cnt:Number of instructions in insns. 139 * - res: Output parameter, result of transformation. 140 * 141 * Return value: 142 * - Zero: pre-processing success. 143 * - Non-zero: pre-processing, stop loading. 144 */ 145 typedef int (*bpf_program_prep_t)(struct bpf_program *prog, int n, 146 struct bpf_insn *insns, int insns_cnt, 147 struct bpf_prog_prep_result *res); 148 149 int bpf_program__set_prep(struct bpf_program *prog, int nr_instance, 150 bpf_program_prep_t prep); 151 152 int bpf_program__nth_fd(struct bpf_program *prog, int n); 153 154 /* 155 * We don't need __attribute__((packed)) now since it is 156 * unnecessary for 'bpf_map_def' because they are all aligned. 157 * In addition, using it will trigger -Wpacked warning message, 158 * and will be treated as an error due to -Werror. 159 */ 160 struct bpf_map_def { 161 unsigned int type; 162 unsigned int key_size; 163 unsigned int value_size; 164 unsigned int max_entries; 165 }; 166 167 /* 168 * There is another 'struct bpf_map' in include/linux/map.h. However, 169 * it is not a uapi header so no need to consider name clash. 170 */ 171 struct bpf_map; 172 struct bpf_map * 173 bpf_object__find_map_by_name(struct bpf_object *obj, const char *name); 174 175 struct bpf_map * 176 bpf_map__next(struct bpf_map *map, struct bpf_object *obj); 177 #define bpf_map__for_each(pos, obj) \ 178 for ((pos) = bpf_map__next(NULL, (obj)); \ 179 (pos) != NULL; \ 180 (pos) = bpf_map__next((pos), (obj))) 181 182 int bpf_map__fd(struct bpf_map *map); 183 const struct bpf_map_def *bpf_map__def(struct bpf_map *map); 184 const char *bpf_map__name(struct bpf_map *map); 185 186 typedef void (*bpf_map_clear_priv_t)(struct bpf_map *, void *); 187 int bpf_map__set_priv(struct bpf_map *map, void *priv, 188 bpf_map_clear_priv_t clear_priv); 189 void *bpf_map__priv(struct bpf_map *map); 190 191 #endif 192