tools/lib/bpf/libbpf.h

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