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 #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