1 /* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
2
3 /*
4 * Internal libbpf helpers.
5 *
6 * Copyright (c) 2019 Facebook
7 */
8
9 #ifndef __LIBBPF_LIBBPF_INTERNAL_H
10 #define __LIBBPF_LIBBPF_INTERNAL_H
11
12 #include <stdlib.h>
13 #include <limits.h>
14
15 /* make sure libbpf doesn't use kernel-only integer typedefs */
16 #pragma GCC poison u8 u16 u32 u64 s8 s16 s32 s64
17
18 /* prevent accidental re-addition of reallocarray() */
19 #pragma GCC poison reallocarray
20
21 #include "libbpf.h"
22
23 #define BTF_INFO_ENC(kind, kind_flag, vlen) \
24 ((!!(kind_flag) << 31) | ((kind) << 24) | ((vlen) & BTF_MAX_VLEN))
25 #define BTF_TYPE_ENC(name, info, size_or_type) (name), (info), (size_or_type)
26 #define BTF_INT_ENC(encoding, bits_offset, nr_bits) \
27 ((encoding) << 24 | (bits_offset) << 16 | (nr_bits))
28 #define BTF_TYPE_INT_ENC(name, encoding, bits_offset, bits, sz) \
29 BTF_TYPE_ENC(name, BTF_INFO_ENC(BTF_KIND_INT, 0, 0), sz), \
30 BTF_INT_ENC(encoding, bits_offset, bits)
31 #define BTF_MEMBER_ENC(name, type, bits_offset) (name), (type), (bits_offset)
32 #define BTF_PARAM_ENC(name, type) (name), (type)
33 #define BTF_VAR_SECINFO_ENC(type, offset, size) (type), (offset), (size)
34
35 #ifndef likely
36 #define likely(x) __builtin_expect(!!(x), 1)
37 #endif
38 #ifndef unlikely
39 #define unlikely(x) __builtin_expect(!!(x), 0)
40 #endif
41 #ifndef min
42 # define min(x, y) ((x) < (y) ? (x) : (y))
43 #endif
44 #ifndef max
45 # define max(x, y) ((x) < (y) ? (y) : (x))
46 #endif
47 #ifndef offsetofend
48 # define offsetofend(TYPE, FIELD) \
49 (offsetof(TYPE, FIELD) + sizeof(((TYPE *)0)->FIELD))
50 #endif
51
52 /* Symbol versioning is different between static and shared library.
53 * Properly versioned symbols are needed for shared library, but
54 * only the symbol of the new version is needed for static library.
55 */
56 #ifdef SHARED
57 # define COMPAT_VERSION(internal_name, api_name, version) \
58 asm(".symver " #internal_name "," #api_name "@" #version);
59 # define DEFAULT_VERSION(internal_name, api_name, version) \
60 asm(".symver " #internal_name "," #api_name "@@" #version);
61 #else
62 # define COMPAT_VERSION(internal_name, api_name, version)
63 # define DEFAULT_VERSION(internal_name, api_name, version) \
64 extern typeof(internal_name) api_name \
65 __attribute__((alias(#internal_name)));
66 #endif
67
68 extern void libbpf_print(enum libbpf_print_level level,
69 const char *format, ...)
70 __attribute__((format(printf, 2, 3)));
71
72 #define __pr(level, fmt, ...) \
73 do { \
74 libbpf_print(level, "libbpf: " fmt, ##__VA_ARGS__); \
75 } while (0)
76
77 #define pr_warn(fmt, ...) __pr(LIBBPF_WARN, fmt, ##__VA_ARGS__)
78 #define pr_info(fmt, ...) __pr(LIBBPF_INFO, fmt, ##__VA_ARGS__)
79 #define pr_debug(fmt, ...) __pr(LIBBPF_DEBUG, fmt, ##__VA_ARGS__)
80
81 #ifndef __has_builtin
82 #define __has_builtin(x) 0
83 #endif
84 /*
85 * Re-implement glibc's reallocarray() for libbpf internal-only use.
86 * reallocarray(), unfortunately, is not available in all versions of glibc,
87 * so requires extra feature detection and using reallocarray() stub from
88 * <tools/libc_compat.h> and COMPAT_NEED_REALLOCARRAY. All this complicates
89 * build of libbpf unnecessarily and is just a maintenance burden. Instead,
90 * it's trivial to implement libbpf-specific internal version and use it
91 * throughout libbpf.
92 */
libbpf_reallocarray(void * ptr,size_t nmemb,size_t size)93 static inline void *libbpf_reallocarray(void *ptr, size_t nmemb, size_t size)
94 {
95 size_t total;
96
97 #if __has_builtin(__builtin_mul_overflow)
98 if (unlikely(__builtin_mul_overflow(nmemb, size, &total)))
99 return NULL;
100 #else
101 if (size == 0 || nmemb > ULONG_MAX / size)
102 return NULL;
103 total = nmemb * size;
104 #endif
105 return realloc(ptr, total);
106 }
107
108 void *btf_add_mem(void **data, size_t *cap_cnt, size_t elem_sz,
109 size_t cur_cnt, size_t max_cnt, size_t add_cnt);
110 int btf_ensure_mem(void **data, size_t *cap_cnt, size_t elem_sz, size_t need_cnt);
111
libbpf_validate_opts(const char * opts,size_t opts_sz,size_t user_sz,const char * type_name)112 static inline bool libbpf_validate_opts(const char *opts,
113 size_t opts_sz, size_t user_sz,
114 const char *type_name)
115 {
116 if (user_sz < sizeof(size_t)) {
117 pr_warn("%s size (%zu) is too small\n", type_name, user_sz);
118 return false;
119 }
120 if (user_sz > opts_sz) {
121 size_t i;
122
123 for (i = opts_sz; i < user_sz; i++) {
124 if (opts[i]) {
125 pr_warn("%s has non-zero extra bytes\n",
126 type_name);
127 return false;
128 }
129 }
130 }
131 return true;
132 }
133
134 #define OPTS_VALID(opts, type) \
135 (!(opts) || libbpf_validate_opts((const char *)opts, \
136 offsetofend(struct type, \
137 type##__last_field), \
138 (opts)->sz, #type))
139 #define OPTS_HAS(opts, field) \
140 ((opts) && opts->sz >= offsetofend(typeof(*(opts)), field))
141 #define OPTS_GET(opts, field, fallback_value) \
142 (OPTS_HAS(opts, field) ? (opts)->field : fallback_value)
143 #define OPTS_SET(opts, field, value) \
144 do { \
145 if (OPTS_HAS(opts, field)) \
146 (opts)->field = value; \
147 } while (0)
148
149 int parse_cpu_mask_str(const char *s, bool **mask, int *mask_sz);
150 int parse_cpu_mask_file(const char *fcpu, bool **mask, int *mask_sz);
151 int libbpf__load_raw_btf(const char *raw_types, size_t types_len,
152 const char *str_sec, size_t str_len);
153
154 int bpf_object__section_size(const struct bpf_object *obj, const char *name,
155 __u32 *size);
156 int bpf_object__variable_offset(const struct bpf_object *obj, const char *name,
157 __u32 *off);
158
159 struct btf_ext_info {
160 /*
161 * info points to the individual info section (e.g. func_info and
162 * line_info) from the .BTF.ext. It does not include the __u32 rec_size.
163 */
164 void *info;
165 __u32 rec_size;
166 __u32 len;
167 };
168
169 #define for_each_btf_ext_sec(seg, sec) \
170 for (sec = (seg)->info; \
171 (void *)sec < (seg)->info + (seg)->len; \
172 sec = (void *)sec + sizeof(struct btf_ext_info_sec) + \
173 (seg)->rec_size * sec->num_info)
174
175 #define for_each_btf_ext_rec(seg, sec, i, rec) \
176 for (i = 0, rec = (void *)&(sec)->data; \
177 i < (sec)->num_info; \
178 i++, rec = (void *)rec + (seg)->rec_size)
179
180 /*
181 * The .BTF.ext ELF section layout defined as
182 * struct btf_ext_header
183 * func_info subsection
184 *
185 * The func_info subsection layout:
186 * record size for struct bpf_func_info in the func_info subsection
187 * struct btf_sec_func_info for section #1
188 * a list of bpf_func_info records for section #1
189 * where struct bpf_func_info mimics one in include/uapi/linux/bpf.h
190 * but may not be identical
191 * struct btf_sec_func_info for section #2
192 * a list of bpf_func_info records for section #2
193 * ......
194 *
195 * Note that the bpf_func_info record size in .BTF.ext may not
196 * be the same as the one defined in include/uapi/linux/bpf.h.
197 * The loader should ensure that record_size meets minimum
198 * requirement and pass the record as is to the kernel. The
199 * kernel will handle the func_info properly based on its contents.
200 */
201 struct btf_ext_header {
202 __u16 magic;
203 __u8 version;
204 __u8 flags;
205 __u32 hdr_len;
206
207 /* All offsets are in bytes relative to the end of this header */
208 __u32 func_info_off;
209 __u32 func_info_len;
210 __u32 line_info_off;
211 __u32 line_info_len;
212
213 /* optional part of .BTF.ext header */
214 __u32 core_relo_off;
215 __u32 core_relo_len;
216 };
217
218 struct btf_ext {
219 union {
220 struct btf_ext_header *hdr;
221 void *data;
222 };
223 struct btf_ext_info func_info;
224 struct btf_ext_info line_info;
225 struct btf_ext_info core_relo_info;
226 __u32 data_size;
227 };
228
229 struct btf_ext_info_sec {
230 __u32 sec_name_off;
231 __u32 num_info;
232 /* Followed by num_info * record_size number of bytes */
233 __u8 data[];
234 };
235
236 /* The minimum bpf_func_info checked by the loader */
237 struct bpf_func_info_min {
238 __u32 insn_off;
239 __u32 type_id;
240 };
241
242 /* The minimum bpf_line_info checked by the loader */
243 struct bpf_line_info_min {
244 __u32 insn_off;
245 __u32 file_name_off;
246 __u32 line_off;
247 __u32 line_col;
248 };
249
250 /* bpf_core_relo_kind encodes which aspect of captured field/type/enum value
251 * has to be adjusted by relocations.
252 */
253 enum bpf_core_relo_kind {
254 BPF_FIELD_BYTE_OFFSET = 0, /* field byte offset */
255 BPF_FIELD_BYTE_SIZE = 1, /* field size in bytes */
256 BPF_FIELD_EXISTS = 2, /* field existence in target kernel */
257 BPF_FIELD_SIGNED = 3, /* field signedness (0 - unsigned, 1 - signed) */
258 BPF_FIELD_LSHIFT_U64 = 4, /* bitfield-specific left bitshift */
259 BPF_FIELD_RSHIFT_U64 = 5, /* bitfield-specific right bitshift */
260 BPF_TYPE_ID_LOCAL = 6, /* type ID in local BPF object */
261 BPF_TYPE_ID_TARGET = 7, /* type ID in target kernel */
262 BPF_TYPE_EXISTS = 8, /* type existence in target kernel */
263 BPF_TYPE_SIZE = 9, /* type size in bytes */
264 BPF_ENUMVAL_EXISTS = 10, /* enum value existence in target kernel */
265 BPF_ENUMVAL_VALUE = 11, /* enum value integer value */
266 };
267
268 /* The minimum bpf_core_relo checked by the loader
269 *
270 * CO-RE relocation captures the following data:
271 * - insn_off - instruction offset (in bytes) within a BPF program that needs
272 * its insn->imm field to be relocated with actual field info;
273 * - type_id - BTF type ID of the "root" (containing) entity of a relocatable
274 * type or field;
275 * - access_str_off - offset into corresponding .BTF string section. String
276 * interpretation depends on specific relocation kind:
277 * - for field-based relocations, string encodes an accessed field using
278 * a sequence of field and array indices, separated by colon (:). It's
279 * conceptually very close to LLVM's getelementptr ([0]) instruction's
280 * arguments for identifying offset to a field.
281 * - for type-based relocations, strings is expected to be just "0";
282 * - for enum value-based relocations, string contains an index of enum
283 * value within its enum type;
284 *
285 * Example to provide a better feel.
286 *
287 * struct sample {
288 * int a;
289 * struct {
290 * int b[10];
291 * };
292 * };
293 *
294 * struct sample *s = ...;
295 * int x = &s->a; // encoded as "0:0" (a is field #0)
296 * int y = &s->b[5]; // encoded as "0:1:0:5" (anon struct is field #1,
297 * // b is field #0 inside anon struct, accessing elem #5)
298 * int z = &s[10]->b; // encoded as "10:1" (ptr is used as an array)
299 *
300 * type_id for all relocs in this example will capture BTF type id of
301 * `struct sample`.
302 *
303 * Such relocation is emitted when using __builtin_preserve_access_index()
304 * Clang built-in, passing expression that captures field address, e.g.:
305 *
306 * bpf_probe_read(&dst, sizeof(dst),
307 * __builtin_preserve_access_index(&src->a.b.c));
308 *
309 * In this case Clang will emit field relocation recording necessary data to
310 * be able to find offset of embedded `a.b.c` field within `src` struct.
311 *
312 * [0] https://llvm.org/docs/LangRef.html#getelementptr-instruction
313 */
314 struct bpf_core_relo {
315 __u32 insn_off;
316 __u32 type_id;
317 __u32 access_str_off;
318 enum bpf_core_relo_kind kind;
319 };
320
321 #endif /* __LIBBPF_LIBBPF_INTERNAL_H */
322
