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__get_name(struct bpf_object *obj); 59 unsigned int bpf_object__get_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_private(struct bpf_program *prog, void *priv, 82 bpf_program_clear_priv_t clear_priv); 83 84 int bpf_program__get_private(struct bpf_program *prog, 85 void **ppriv); 86 87 const char *bpf_program__title(struct bpf_program *prog, bool needs_copy); 88 89 int bpf_program__fd(struct bpf_program *prog); 90 91 struct bpf_insn; 92 93 /* 94 * Libbpf allows callers to adjust BPF programs before being loaded 95 * into kernel. One program in an object file can be transform into 96 * multiple variants to be attached to different code. 97 * 98 * bpf_program_prep_t, bpf_program__set_prep and bpf_program__nth_fd 99 * are APIs for this propose. 100 * 101 * - bpf_program_prep_t: 102 * It defines 'preprocessor', which is a caller defined function 103 * passed to libbpf through bpf_program__set_prep(), and will be 104 * called before program is loaded. The processor should adjust 105 * the program one time for each instances according to the number 106 * passed to it. 107 * 108 * - bpf_program__set_prep: 109 * Attachs a preprocessor to a BPF program. The number of instances 110 * whould be created is also passed through this function. 111 * 112 * - bpf_program__nth_fd: 113 * After the program is loaded, get resuling fds from bpf program for 114 * each instances. 115 * 116 * If bpf_program__set_prep() is not used, the program whould be loaded 117 * without adjustment during bpf_object__load(). The program has only 118 * one instance. In this case bpf_program__fd(prog) is equal to 119 * bpf_program__nth_fd(prog, 0). 120 */ 121 122 struct bpf_prog_prep_result { 123 /* 124 * If not NULL, load new instruction array. 125 * If set to NULL, don't load this instance. 126 */ 127 struct bpf_insn *new_insn_ptr; 128 int new_insn_cnt; 129 130 /* If not NULL, result fd is set to it */ 131 int *pfd; 132 }; 133 134 /* 135 * Parameters of bpf_program_prep_t: 136 * - prog: The bpf_program being loaded. 137 * - n: Index of instance being generated. 138 * - insns: BPF instructions array. 139 * - insns_cnt:Number of instructions in insns. 140 * - res: Output parameter, result of transformation. 141 * 142 * Return value: 143 * - Zero: pre-processing success. 144 * - Non-zero: pre-processing, stop loading. 145 */ 146 typedef int (*bpf_program_prep_t)(struct bpf_program *prog, int n, 147 struct bpf_insn *insns, int insns_cnt, 148 struct bpf_prog_prep_result *res); 149 150 int bpf_program__set_prep(struct bpf_program *prog, int nr_instance, 151 bpf_program_prep_t prep); 152 153 int bpf_program__nth_fd(struct bpf_program *prog, int n); 154 155 /* 156 * We don't need __attribute__((packed)) now since it is 157 * unnecessary for 'bpf_map_def' because they are all aligned. 158 * In addition, using it will trigger -Wpacked warning message, 159 * and will be treated as an error due to -Werror. 160 */ 161 struct bpf_map_def { 162 unsigned int type; 163 unsigned int key_size; 164 unsigned int value_size; 165 unsigned int max_entries; 166 }; 167 168 /* 169 * There is another 'struct bpf_map' in include/linux/map.h. However, 170 * it is not a uapi header so no need to consider name clash. 171 */ 172 struct bpf_map; 173 struct bpf_map * 174 bpf_object__get_map_by_name(struct bpf_object *obj, const char *name); 175 176 struct bpf_map * 177 bpf_map__next(struct bpf_map *map, struct bpf_object *obj); 178 #define bpf_map__for_each(pos, obj) \ 179 for ((pos) = bpf_map__next(NULL, (obj)); \ 180 (pos) != NULL; \ 181 (pos) = bpf_map__next((pos), (obj))) 182 183 int bpf_map__get_fd(struct bpf_map *map); 184 int bpf_map__get_def(struct bpf_map *map, struct bpf_map_def *pdef); 185 const char *bpf_map__get_name(struct bpf_map *map); 186 187 typedef void (*bpf_map_clear_priv_t)(struct bpf_map *, void *); 188 int bpf_map__set_private(struct bpf_map *map, void *priv, 189 bpf_map_clear_priv_t clear_priv); 190 int bpf_map__get_private(struct bpf_map *map, void **ppriv); 191 192 #endif 193