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 <stdint.h>
  26 #include <stdbool.h>
  27 #include <sys/types.h>  // for size_t
  28 #include <linux/bpf.h>
  29
  30 enum libbpf_errno {
  31         __LIBBPF_ERRNO__START = 4000,
  32
  33         /* Something wrong in libelf */
  34         LIBBPF_ERRNO__LIBELF = __LIBBPF_ERRNO__START,
  35         LIBBPF_ERRNO__FORMAT,   /* BPF object format invalid */
  36         LIBBPF_ERRNO__KVERSION, /* Incorrect or no 'version' section */
  37         LIBBPF_ERRNO__ENDIAN,   /* Endian mismatch */
  38         LIBBPF_ERRNO__INTERNAL, /* Internal error in libbpf */
  39         LIBBPF_ERRNO__RELOC,    /* Relocation failed */
  40         LIBBPF_ERRNO__LOAD,     /* Load program failure for unknown reason */
  41         LIBBPF_ERRNO__VERIFY,   /* Kernel verifier blocks program loading */
  42         LIBBPF_ERRNO__PROG2BIG, /* Program too big */
  43         LIBBPF_ERRNO__KVER,     /* Incorrect kernel version */
  44         LIBBPF_ERRNO__PROGTYPE, /* Kernel doesn't support this program type */
  45         __LIBBPF_ERRNO__END,
  46 };
  47
  48 int libbpf_strerror(int err, char *buf, size_t size);
  49
  50 /*
  51  * In include/linux/compiler-gcc.h, __printf is defined. However
  52  * it should be better if libbpf.h doesn't depend on Linux header file.
  53  * So instead of __printf, here we use gcc attribute directly.
  54  */
  55 typedef int (*libbpf_print_fn_t)(const char *, ...)
  56         __attribute__((format(printf, 1, 2)));
  57
  58 void libbpf_set_print(libbpf_print_fn_t warn,
  59                       libbpf_print_fn_t info,
  60                       libbpf_print_fn_t debug);
  61
  62 /* Hide internal to user */
  63 struct bpf_object;
  64
  65 struct bpf_object *bpf_object__open(const char *path);
  66 struct bpf_object *bpf_object__open_buffer(void *obj_buf,
  67                                            size_t obj_buf_sz,
  68                                            const char *name);
  69 int bpf_object__pin(struct bpf_object *object, const char *path);
  70 void bpf_object__close(struct bpf_object *object);
  71
  72 /* Load/unload object into/from kernel */
  73 int bpf_object__load(struct bpf_object *obj);
  74 int bpf_object__unload(struct bpf_object *obj);
  75 const char *bpf_object__name(struct bpf_object *obj);
  76 unsigned int bpf_object__kversion(struct bpf_object *obj);
  77
  78 struct bpf_object *bpf_object__next(struct bpf_object *prev);
  79 #define bpf_object__for_each_safe(pos, tmp)                     \
  80         for ((pos) = bpf_object__next(NULL),            \
  81                 (tmp) = bpf_object__next(pos);          \
  82              (pos) != NULL;                             \
  83              (pos) = (tmp), (tmp) = bpf_object__next(tmp))
  84
  85 typedef void (*bpf_object_clear_priv_t)(struct bpf_object *, void *);
  86 int bpf_object__set_priv(struct bpf_object *obj, void *priv,
  87                          bpf_object_clear_priv_t clear_priv);
  88 void *bpf_object__priv(struct bpf_object *prog);
  89
  90 /* Accessors of bpf_program. */
  91 struct bpf_program;
  92 struct bpf_program *bpf_program__next(struct bpf_program *prog,
  93                                       struct bpf_object *obj);
  94
  95 #define bpf_object__for_each_program(pos, obj)          \
  96         for ((pos) = bpf_program__next(NULL, (obj));    \
  97              (pos) != NULL;                             \
  98              (pos) = bpf_program__next((pos), (obj)))
  99
 100 typedef void (*bpf_program_clear_priv_t)(struct bpf_program *,
 101                                          void *);
 102
 103 int bpf_program__set_priv(struct bpf_program *prog, void *priv,
 104                           bpf_program_clear_priv_t clear_priv);
 105
 106 void *bpf_program__priv(struct bpf_program *prog);
 107
 108 const char *bpf_program__title(struct bpf_program *prog, bool needs_copy);
 109
 110 int bpf_program__fd(struct bpf_program *prog);
 111 int bpf_program__pin_instance(struct bpf_program *prog, const char *path,
 112                               int instance);
 113 int bpf_program__pin(struct bpf_program *prog, const char *path);
 114
 115 struct bpf_insn;
 116
 117 /*
 118  * Libbpf allows callers to adjust BPF programs before being loaded
 119  * into kernel. One program in an object file can be transform into
 120  * multiple variants to be attached to different code.
 121  *
 122  * bpf_program_prep_t, bpf_program__set_prep and bpf_program__nth_fd
 123  * are APIs for this propose.
 124  *
 125  * - bpf_program_prep_t:
 126  *   It defines 'preprocessor', which is a caller defined function
 127  *   passed to libbpf through bpf_program__set_prep(), and will be
 128  *   called before program is loaded. The processor should adjust
 129  *   the program one time for each instances according to the number
 130  *   passed to it.
 131  *
 132  * - bpf_program__set_prep:
 133  *   Attachs a preprocessor to a BPF program. The number of instances
 134  *   whould be created is also passed through this function.
 135  *
 136  * - bpf_program__nth_fd:
 137  *   After the program is loaded, get resuling fds from bpf program for
 138  *   each instances.
 139  *
 140  * If bpf_program__set_prep() is not used, the program whould be loaded
 141  * without adjustment during bpf_object__load(). The program has only
 142  * one instance. In this case bpf_program__fd(prog) is equal to
 143  * bpf_program__nth_fd(prog, 0).
 144  */
 145
 146 struct bpf_prog_prep_result {
 147         /*
 148          * If not NULL, load new instruction array.
 149          * If set to NULL, don't load this instance.
 150          */
 151         struct bpf_insn *new_insn_ptr;
 152         int new_insn_cnt;
 153
 154         /* If not NULL, result fd is set to it */
 155         int *pfd;
 156 };
 157
 158 /*
 159  * Parameters of bpf_program_prep_t:
 160  *  - prog:     The bpf_program being loaded.
 161  *  - n:        Index of instance being generated.
 162  *  - insns:    BPF instructions array.
 163  *  - insns_cnt:Number of instructions in insns.
 164  *  - res:      Output parameter, result of transformation.
 165  *
 166  * Return value:
 167  *  - Zero: pre-processing success.
 168  *  - Non-zero: pre-processing, stop loading.
 169  */
 170 typedef int (*bpf_program_prep_t)(struct bpf_program *prog, int n,
 171                                   struct bpf_insn *insns, int insns_cnt,
 172                                   struct bpf_prog_prep_result *res);
 173
 174 int bpf_program__set_prep(struct bpf_program *prog, int nr_instance,
 175                           bpf_program_prep_t prep);
 176
 177 int bpf_program__nth_fd(struct bpf_program *prog, int n);
 178
 179 /*
 180  * Adjust type of bpf program. Default is kprobe.
 181  */
 182 int bpf_program__set_socket_filter(struct bpf_program *prog);
 183 int bpf_program__set_tracepoint(struct bpf_program *prog);
 184 int bpf_program__set_kprobe(struct bpf_program *prog);
 185 int bpf_program__set_sched_cls(struct bpf_program *prog);
 186 int bpf_program__set_sched_act(struct bpf_program *prog);
 187 int bpf_program__set_xdp(struct bpf_program *prog);
 188 int bpf_program__set_perf_event(struct bpf_program *prog);
 189 void bpf_program__set_type(struct bpf_program *prog, enum bpf_prog_type type);
 190
 191 bool bpf_program__is_socket_filter(struct bpf_program *prog);
 192 bool bpf_program__is_tracepoint(struct bpf_program *prog);
 193 bool bpf_program__is_kprobe(struct bpf_program *prog);
 194 bool bpf_program__is_sched_cls(struct bpf_program *prog);
 195 bool bpf_program__is_sched_act(struct bpf_program *prog);
 196 bool bpf_program__is_xdp(struct bpf_program *prog);
 197 bool bpf_program__is_perf_event(struct bpf_program *prog);
 198
 199 /*
 200  * We don't need __attribute__((packed)) now since it is
 201  * unnecessary for 'bpf_map_def' because they are all aligned.
 202  * In addition, using it will trigger -Wpacked warning message,
 203  * and will be treated as an error due to -Werror.
 204  */
 205 struct bpf_map_def {
 206         unsigned int type;
 207         unsigned int key_size;
 208         unsigned int value_size;
 209         unsigned int max_entries;
 210 };
 211
 212 /*
 213  * There is another 'struct bpf_map' in include/linux/map.h. However,
 214  * it is not a uapi header so no need to consider name clash.
 215  */
 216 struct bpf_map;
 217 struct bpf_map *
 218 bpf_object__find_map_by_name(struct bpf_object *obj, const char *name);
 219
 220 /*
 221  * Get bpf_map through the offset of corresponding struct bpf_map_def
 222  * in the bpf object file.
 223  */
 224 struct bpf_map *
 225 bpf_object__find_map_by_offset(struct bpf_object *obj, size_t offset);
 226
 227 struct bpf_map *
 228 bpf_map__next(struct bpf_map *map, struct bpf_object *obj);
 229 #define bpf_map__for_each(pos, obj)             \
 230         for ((pos) = bpf_map__next(NULL, (obj));        \
 231              (pos) != NULL;                             \
 232              (pos) = bpf_map__next((pos), (obj)))
 233
 234 int bpf_map__fd(struct bpf_map *map);
 235 const struct bpf_map_def *bpf_map__def(struct bpf_map *map);
 236 const char *bpf_map__name(struct bpf_map *map);
 237
 238 typedef void (*bpf_map_clear_priv_t)(struct bpf_map *, void *);
 239 int bpf_map__set_priv(struct bpf_map *map, void *priv,
 240                       bpf_map_clear_priv_t clear_priv);
 241 void *bpf_map__priv(struct bpf_map *map);
 242 int bpf_map__pin(struct bpf_map *map, const char *path);
 243
 244 long libbpf_get_error(const void *ptr);
 245
 246 #endif