xref: /openbmc/linux/tools/lib/bpf/btf.h (revision aa5b395b)
1 /* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
2 /* Copyright (c) 2018 Facebook */
3 
4 #ifndef __LIBBPF_BTF_H
5 #define __LIBBPF_BTF_H
6 
7 #include <stdarg.h>
8 #include <linux/btf.h>
9 #include <linux/types.h>
10 
11 #include "libbpf_common.h"
12 
13 #ifdef __cplusplus
14 extern "C" {
15 #endif
16 
17 #define BTF_ELF_SEC ".BTF"
18 #define BTF_EXT_ELF_SEC ".BTF.ext"
19 #define MAPS_ELF_SEC ".maps"
20 
21 struct btf;
22 struct btf_ext;
23 struct btf_type;
24 
25 struct bpf_object;
26 
27 /*
28  * The .BTF.ext ELF section layout defined as
29  *   struct btf_ext_header
30  *   func_info subsection
31  *
32  * The func_info subsection layout:
33  *   record size for struct bpf_func_info in the func_info subsection
34  *   struct btf_sec_func_info for section #1
35  *   a list of bpf_func_info records for section #1
36  *     where struct bpf_func_info mimics one in include/uapi/linux/bpf.h
37  *     but may not be identical
38  *   struct btf_sec_func_info for section #2
39  *   a list of bpf_func_info records for section #2
40  *   ......
41  *
42  * Note that the bpf_func_info record size in .BTF.ext may not
43  * be the same as the one defined in include/uapi/linux/bpf.h.
44  * The loader should ensure that record_size meets minimum
45  * requirement and pass the record as is to the kernel. The
46  * kernel will handle the func_info properly based on its contents.
47  */
48 struct btf_ext_header {
49 	__u16	magic;
50 	__u8	version;
51 	__u8	flags;
52 	__u32	hdr_len;
53 
54 	/* All offsets are in bytes relative to the end of this header */
55 	__u32	func_info_off;
56 	__u32	func_info_len;
57 	__u32	line_info_off;
58 	__u32	line_info_len;
59 
60 	/* optional part of .BTF.ext header */
61 	__u32	field_reloc_off;
62 	__u32	field_reloc_len;
63 };
64 
65 LIBBPF_API void btf__free(struct btf *btf);
66 LIBBPF_API struct btf *btf__new(__u8 *data, __u32 size);
67 LIBBPF_API struct btf *btf__parse_elf(const char *path,
68 				      struct btf_ext **btf_ext);
69 LIBBPF_API int btf__finalize_data(struct bpf_object *obj, struct btf *btf);
70 LIBBPF_API int btf__load(struct btf *btf);
71 LIBBPF_API __s32 btf__find_by_name(const struct btf *btf,
72 				   const char *type_name);
73 LIBBPF_API __s32 btf__find_by_name_kind(const struct btf *btf,
74 					const char *type_name, __u32 kind);
75 LIBBPF_API __u32 btf__get_nr_types(const struct btf *btf);
76 LIBBPF_API const struct btf_type *btf__type_by_id(const struct btf *btf,
77 						  __u32 id);
78 LIBBPF_API __s64 btf__resolve_size(const struct btf *btf, __u32 type_id);
79 LIBBPF_API int btf__resolve_type(const struct btf *btf, __u32 type_id);
80 LIBBPF_API int btf__align_of(const struct btf *btf, __u32 id);
81 LIBBPF_API int btf__fd(const struct btf *btf);
82 LIBBPF_API const void *btf__get_raw_data(const struct btf *btf, __u32 *size);
83 LIBBPF_API const char *btf__name_by_offset(const struct btf *btf, __u32 offset);
84 LIBBPF_API int btf__get_from_id(__u32 id, struct btf **btf);
85 LIBBPF_API int btf__get_map_kv_tids(const struct btf *btf, const char *map_name,
86 				    __u32 expected_key_size,
87 				    __u32 expected_value_size,
88 				    __u32 *key_type_id, __u32 *value_type_id);
89 
90 LIBBPF_API struct btf_ext *btf_ext__new(__u8 *data, __u32 size);
91 LIBBPF_API void btf_ext__free(struct btf_ext *btf_ext);
92 LIBBPF_API const void *btf_ext__get_raw_data(const struct btf_ext *btf_ext,
93 					     __u32 *size);
94 LIBBPF_API int btf_ext__reloc_func_info(const struct btf *btf,
95 					const struct btf_ext *btf_ext,
96 					const char *sec_name, __u32 insns_cnt,
97 					void **func_info, __u32 *cnt);
98 LIBBPF_API int btf_ext__reloc_line_info(const struct btf *btf,
99 					const struct btf_ext *btf_ext,
100 					const char *sec_name, __u32 insns_cnt,
101 					void **line_info, __u32 *cnt);
102 LIBBPF_API __u32 btf_ext__func_info_rec_size(const struct btf_ext *btf_ext);
103 LIBBPF_API __u32 btf_ext__line_info_rec_size(const struct btf_ext *btf_ext);
104 
105 LIBBPF_API struct btf *libbpf_find_kernel_btf(void);
106 
107 struct btf_dedup_opts {
108 	unsigned int dedup_table_size;
109 	bool dont_resolve_fwds;
110 };
111 
112 LIBBPF_API int btf__dedup(struct btf *btf, struct btf_ext *btf_ext,
113 			  const struct btf_dedup_opts *opts);
114 
115 struct btf_dump;
116 
117 struct btf_dump_opts {
118 	void *ctx;
119 };
120 
121 typedef void (*btf_dump_printf_fn_t)(void *ctx, const char *fmt, va_list args);
122 
123 LIBBPF_API struct btf_dump *btf_dump__new(const struct btf *btf,
124 					  const struct btf_ext *btf_ext,
125 					  const struct btf_dump_opts *opts,
126 					  btf_dump_printf_fn_t printf_fn);
127 LIBBPF_API void btf_dump__free(struct btf_dump *d);
128 
129 LIBBPF_API int btf_dump__dump_type(struct btf_dump *d, __u32 id);
130 
131 struct btf_dump_emit_type_decl_opts {
132 	/* size of this struct, for forward/backward compatiblity */
133 	size_t sz;
134 	/* optional field name for type declaration, e.g.:
135 	 * - struct my_struct <FNAME>
136 	 * - void (*<FNAME>)(int)
137 	 * - char (*<FNAME>)[123]
138 	 */
139 	const char *field_name;
140 	/* extra indentation level (in number of tabs) to emit for multi-line
141 	 * type declarations (e.g., anonymous struct); applies for lines
142 	 * starting from the second one (first line is assumed to have
143 	 * necessary indentation already
144 	 */
145 	int indent_level;
146 };
147 #define btf_dump_emit_type_decl_opts__last_field indent_level
148 
149 LIBBPF_API int
150 btf_dump__emit_type_decl(struct btf_dump *d, __u32 id,
151 			 const struct btf_dump_emit_type_decl_opts *opts);
152 
153 /*
154  * A set of helpers for easier BTF types handling
155  */
156 static inline __u16 btf_kind(const struct btf_type *t)
157 {
158 	return BTF_INFO_KIND(t->info);
159 }
160 
161 static inline __u16 btf_vlen(const struct btf_type *t)
162 {
163 	return BTF_INFO_VLEN(t->info);
164 }
165 
166 static inline bool btf_kflag(const struct btf_type *t)
167 {
168 	return BTF_INFO_KFLAG(t->info);
169 }
170 
171 static inline bool btf_is_int(const struct btf_type *t)
172 {
173 	return btf_kind(t) == BTF_KIND_INT;
174 }
175 
176 static inline bool btf_is_ptr(const struct btf_type *t)
177 {
178 	return btf_kind(t) == BTF_KIND_PTR;
179 }
180 
181 static inline bool btf_is_array(const struct btf_type *t)
182 {
183 	return btf_kind(t) == BTF_KIND_ARRAY;
184 }
185 
186 static inline bool btf_is_struct(const struct btf_type *t)
187 {
188 	return btf_kind(t) == BTF_KIND_STRUCT;
189 }
190 
191 static inline bool btf_is_union(const struct btf_type *t)
192 {
193 	return btf_kind(t) == BTF_KIND_UNION;
194 }
195 
196 static inline bool btf_is_composite(const struct btf_type *t)
197 {
198 	__u16 kind = btf_kind(t);
199 
200 	return kind == BTF_KIND_STRUCT || kind == BTF_KIND_UNION;
201 }
202 
203 static inline bool btf_is_enum(const struct btf_type *t)
204 {
205 	return btf_kind(t) == BTF_KIND_ENUM;
206 }
207 
208 static inline bool btf_is_fwd(const struct btf_type *t)
209 {
210 	return btf_kind(t) == BTF_KIND_FWD;
211 }
212 
213 static inline bool btf_is_typedef(const struct btf_type *t)
214 {
215 	return btf_kind(t) == BTF_KIND_TYPEDEF;
216 }
217 
218 static inline bool btf_is_volatile(const struct btf_type *t)
219 {
220 	return btf_kind(t) == BTF_KIND_VOLATILE;
221 }
222 
223 static inline bool btf_is_const(const struct btf_type *t)
224 {
225 	return btf_kind(t) == BTF_KIND_CONST;
226 }
227 
228 static inline bool btf_is_restrict(const struct btf_type *t)
229 {
230 	return btf_kind(t) == BTF_KIND_RESTRICT;
231 }
232 
233 static inline bool btf_is_mod(const struct btf_type *t)
234 {
235 	__u16 kind = btf_kind(t);
236 
237 	return kind == BTF_KIND_VOLATILE ||
238 	       kind == BTF_KIND_CONST ||
239 	       kind == BTF_KIND_RESTRICT;
240 }
241 
242 static inline bool btf_is_func(const struct btf_type *t)
243 {
244 	return btf_kind(t) == BTF_KIND_FUNC;
245 }
246 
247 static inline bool btf_is_func_proto(const struct btf_type *t)
248 {
249 	return btf_kind(t) == BTF_KIND_FUNC_PROTO;
250 }
251 
252 static inline bool btf_is_var(const struct btf_type *t)
253 {
254 	return btf_kind(t) == BTF_KIND_VAR;
255 }
256 
257 static inline bool btf_is_datasec(const struct btf_type *t)
258 {
259 	return btf_kind(t) == BTF_KIND_DATASEC;
260 }
261 
262 static inline __u8 btf_int_encoding(const struct btf_type *t)
263 {
264 	return BTF_INT_ENCODING(*(__u32 *)(t + 1));
265 }
266 
267 static inline __u8 btf_int_offset(const struct btf_type *t)
268 {
269 	return BTF_INT_OFFSET(*(__u32 *)(t + 1));
270 }
271 
272 static inline __u8 btf_int_bits(const struct btf_type *t)
273 {
274 	return BTF_INT_BITS(*(__u32 *)(t + 1));
275 }
276 
277 static inline struct btf_array *btf_array(const struct btf_type *t)
278 {
279 	return (struct btf_array *)(t + 1);
280 }
281 
282 static inline struct btf_enum *btf_enum(const struct btf_type *t)
283 {
284 	return (struct btf_enum *)(t + 1);
285 }
286 
287 static inline struct btf_member *btf_members(const struct btf_type *t)
288 {
289 	return (struct btf_member *)(t + 1);
290 }
291 
292 /* Get bit offset of a member with specified index. */
293 static inline __u32 btf_member_bit_offset(const struct btf_type *t,
294 					  __u32 member_idx)
295 {
296 	const struct btf_member *m = btf_members(t) + member_idx;
297 	bool kflag = btf_kflag(t);
298 
299 	return kflag ? BTF_MEMBER_BIT_OFFSET(m->offset) : m->offset;
300 }
301 /*
302  * Get bitfield size of a member, assuming t is BTF_KIND_STRUCT or
303  * BTF_KIND_UNION. If member is not a bitfield, zero is returned.
304  */
305 static inline __u32 btf_member_bitfield_size(const struct btf_type *t,
306 					     __u32 member_idx)
307 {
308 	const struct btf_member *m = btf_members(t) + member_idx;
309 	bool kflag = btf_kflag(t);
310 
311 	return kflag ? BTF_MEMBER_BITFIELD_SIZE(m->offset) : 0;
312 }
313 
314 static inline struct btf_param *btf_params(const struct btf_type *t)
315 {
316 	return (struct btf_param *)(t + 1);
317 }
318 
319 static inline struct btf_var *btf_var(const struct btf_type *t)
320 {
321 	return (struct btf_var *)(t + 1);
322 }
323 
324 static inline struct btf_var_secinfo *
325 btf_var_secinfos(const struct btf_type *t)
326 {
327 	return (struct btf_var_secinfo *)(t + 1);
328 }
329 
330 #ifdef __cplusplus
331 } /* extern "C" */
332 #endif
333 
334 #endif /* __LIBBPF_BTF_H */
335