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
 15enum 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
 32int 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 */
 39typedef int (*libbpf_print_fn_t)(const char *, ...)
 40	__attribute__((format(printf, 1, 2)));
 41
 42void 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 */
 47struct bpf_object;
 48
 49struct bpf_object *bpf_object__open(const char *path);
 50struct bpf_object *bpf_object__open_buffer(void *obj_buf,
 51					   size_t obj_buf_sz,
 52					   const char *name);
 53void bpf_object__close(struct bpf_object *object);
 54
 55/* Load/unload object into/from kernel */
 56int bpf_object__load(struct bpf_object *obj);
 57int bpf_object__unload(struct bpf_object *obj);
 58const char *bpf_object__get_name(struct bpf_object *obj);
 59unsigned int bpf_object__get_kversion(struct bpf_object *obj);
 60
 61struct 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. */
 69struct bpf_program;
 70struct 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
 78typedef void (*bpf_program_clear_priv_t)(struct bpf_program *,
 79					 void *);
 80
 81int bpf_program__set_private(struct bpf_program *prog, void *priv,
 82			     bpf_program_clear_priv_t clear_priv);
 83
 84int bpf_program__get_private(struct bpf_program *prog,
 85			     void **ppriv);
 86
 87const char *bpf_program__title(struct bpf_program *prog, bool needs_copy);
 88
 89int bpf_program__fd(struct bpf_program *prog);
 90
 91struct 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
122struct 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 */
146typedef 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
150int bpf_program__set_prep(struct bpf_program *prog, int nr_instance,
151			  bpf_program_prep_t prep);
152
153int 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 */
161struct 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 */
172struct bpf_map;
173struct bpf_map *
174bpf_object__get_map_by_name(struct bpf_object *obj, const char *name);
175
176struct bpf_map *
177bpf_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
183int bpf_map__get_fd(struct bpf_map *map);
184int bpf_map__get_def(struct bpf_map *map, struct bpf_map_def *pdef);
185const char *bpf_map__get_name(struct bpf_map *map);
186
187typedef void (*bpf_map_clear_priv_t)(struct bpf_map *, void *);
188int bpf_map__set_private(struct bpf_map *map, void *priv,
189			 bpf_map_clear_priv_t clear_priv);
190int bpf_map__get_private(struct bpf_map *map, void **ppriv);
191
192#endif