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 #ifndef EM_BPF 24 #define EM_BPF 247 25 #endif 26 27 #ifndef R_BPF_64_64 28 #define R_BPF_64_64 1 29 #endif 30 #ifndef R_BPF_64_32 31 #define R_BPF_64_32 10 32 #endif 33 34 #ifndef SHT_LLVM_ADDRSIG 35 #define SHT_LLVM_ADDRSIG 0x6FFF4C03 36 #endif 37 38 /* if libelf is old and doesn't support mmap(), fall back to read() */ 39 #ifndef ELF_C_READ_MMAP 40 #define ELF_C_READ_MMAP ELF_C_READ 41 #endif 42 43 #define BTF_INFO_ENC(kind, kind_flag, vlen) \ 44 ((!!(kind_flag) << 31) | ((kind) << 24) | ((vlen) & BTF_MAX_VLEN)) 45 #define BTF_TYPE_ENC(name, info, size_or_type) (name), (info), (size_or_type) 46 #define BTF_INT_ENC(encoding, bits_offset, nr_bits) \ 47 ((encoding) << 24 | (bits_offset) << 16 | (nr_bits)) 48 #define BTF_TYPE_INT_ENC(name, encoding, bits_offset, bits, sz) \ 49 BTF_TYPE_ENC(name, BTF_INFO_ENC(BTF_KIND_INT, 0, 0), sz), \ 50 BTF_INT_ENC(encoding, bits_offset, bits) 51 #define BTF_MEMBER_ENC(name, type, bits_offset) (name), (type), (bits_offset) 52 #define BTF_PARAM_ENC(name, type) (name), (type) 53 #define BTF_VAR_SECINFO_ENC(type, offset, size) (type), (offset), (size) 54 #define BTF_TYPE_FLOAT_ENC(name, sz) \ 55 BTF_TYPE_ENC(name, BTF_INFO_ENC(BTF_KIND_FLOAT, 0, 0), sz) 56 57 #ifndef likely 58 #define likely(x) __builtin_expect(!!(x), 1) 59 #endif 60 #ifndef unlikely 61 #define unlikely(x) __builtin_expect(!!(x), 0) 62 #endif 63 #ifndef min 64 # define min(x, y) ((x) < (y) ? (x) : (y)) 65 #endif 66 #ifndef max 67 # define max(x, y) ((x) < (y) ? (y) : (x)) 68 #endif 69 #ifndef offsetofend 70 # define offsetofend(TYPE, FIELD) \ 71 (offsetof(TYPE, FIELD) + sizeof(((TYPE *)0)->FIELD)) 72 #endif 73 74 /* Symbol versioning is different between static and shared library. 75 * Properly versioned symbols are needed for shared library, but 76 * only the symbol of the new version is needed for static library. 77 */ 78 #ifdef SHARED 79 # define COMPAT_VERSION(internal_name, api_name, version) \ 80 asm(".symver " #internal_name "," #api_name "@" #version); 81 # define DEFAULT_VERSION(internal_name, api_name, version) \ 82 asm(".symver " #internal_name "," #api_name "@@" #version); 83 #else 84 # define COMPAT_VERSION(internal_name, api_name, version) 85 # define DEFAULT_VERSION(internal_name, api_name, version) \ 86 extern typeof(internal_name) api_name \ 87 __attribute__((alias(#internal_name))); 88 #endif 89 90 extern void libbpf_print(enum libbpf_print_level level, 91 const char *format, ...) 92 __attribute__((format(printf, 2, 3))); 93 94 #define __pr(level, fmt, ...) \ 95 do { \ 96 libbpf_print(level, "libbpf: " fmt, ##__VA_ARGS__); \ 97 } while (0) 98 99 #define pr_warn(fmt, ...) __pr(LIBBPF_WARN, fmt, ##__VA_ARGS__) 100 #define pr_info(fmt, ...) __pr(LIBBPF_INFO, fmt, ##__VA_ARGS__) 101 #define pr_debug(fmt, ...) __pr(LIBBPF_DEBUG, fmt, ##__VA_ARGS__) 102 103 #ifndef __has_builtin 104 #define __has_builtin(x) 0 105 #endif 106 /* 107 * Re-implement glibc's reallocarray() for libbpf internal-only use. 108 * reallocarray(), unfortunately, is not available in all versions of glibc, 109 * so requires extra feature detection and using reallocarray() stub from 110 * <tools/libc_compat.h> and COMPAT_NEED_REALLOCARRAY. All this complicates 111 * build of libbpf unnecessarily and is just a maintenance burden. Instead, 112 * it's trivial to implement libbpf-specific internal version and use it 113 * throughout libbpf. 114 */ 115 static inline void *libbpf_reallocarray(void *ptr, size_t nmemb, size_t size) 116 { 117 size_t total; 118 119 #if __has_builtin(__builtin_mul_overflow) 120 if (unlikely(__builtin_mul_overflow(nmemb, size, &total))) 121 return NULL; 122 #else 123 if (size == 0 || nmemb > ULONG_MAX / size) 124 return NULL; 125 total = nmemb * size; 126 #endif 127 return realloc(ptr, total); 128 } 129 130 struct btf; 131 struct btf_type; 132 133 struct btf_type *btf_type_by_id(struct btf *btf, __u32 type_id); 134 135 void *libbpf_add_mem(void **data, size_t *cap_cnt, size_t elem_sz, 136 size_t cur_cnt, size_t max_cnt, size_t add_cnt); 137 int libbpf_ensure_mem(void **data, size_t *cap_cnt, size_t elem_sz, size_t need_cnt); 138 139 static inline bool libbpf_validate_opts(const char *opts, 140 size_t opts_sz, size_t user_sz, 141 const char *type_name) 142 { 143 if (user_sz < sizeof(size_t)) { 144 pr_warn("%s size (%zu) is too small\n", type_name, user_sz); 145 return false; 146 } 147 if (user_sz > opts_sz) { 148 size_t i; 149 150 for (i = opts_sz; i < user_sz; i++) { 151 if (opts[i]) { 152 pr_warn("%s has non-zero extra bytes\n", 153 type_name); 154 return false; 155 } 156 } 157 } 158 return true; 159 } 160 161 #define OPTS_VALID(opts, type) \ 162 (!(opts) || libbpf_validate_opts((const char *)opts, \ 163 offsetofend(struct type, \ 164 type##__last_field), \ 165 (opts)->sz, #type)) 166 #define OPTS_HAS(opts, field) \ 167 ((opts) && opts->sz >= offsetofend(typeof(*(opts)), field)) 168 #define OPTS_GET(opts, field, fallback_value) \ 169 (OPTS_HAS(opts, field) ? (opts)->field : fallback_value) 170 #define OPTS_SET(opts, field, value) \ 171 do { \ 172 if (OPTS_HAS(opts, field)) \ 173 (opts)->field = value; \ 174 } while (0) 175 176 int parse_cpu_mask_str(const char *s, bool **mask, int *mask_sz); 177 int parse_cpu_mask_file(const char *fcpu, bool **mask, int *mask_sz); 178 int libbpf__load_raw_btf(const char *raw_types, size_t types_len, 179 const char *str_sec, size_t str_len); 180 181 struct bpf_prog_load_params { 182 enum bpf_prog_type prog_type; 183 enum bpf_attach_type expected_attach_type; 184 const char *name; 185 const struct bpf_insn *insns; 186 size_t insn_cnt; 187 const char *license; 188 __u32 kern_version; 189 __u32 attach_prog_fd; 190 __u32 attach_btf_obj_fd; 191 __u32 attach_btf_id; 192 __u32 prog_ifindex; 193 __u32 prog_btf_fd; 194 __u32 prog_flags; 195 196 __u32 func_info_rec_size; 197 const void *func_info; 198 __u32 func_info_cnt; 199 200 __u32 line_info_rec_size; 201 const void *line_info; 202 __u32 line_info_cnt; 203 204 __u32 log_level; 205 char *log_buf; 206 size_t log_buf_sz; 207 }; 208 209 int libbpf__bpf_prog_load(const struct bpf_prog_load_params *load_attr); 210 211 int bpf_object__section_size(const struct bpf_object *obj, const char *name, 212 __u32 *size); 213 int bpf_object__variable_offset(const struct bpf_object *obj, const char *name, 214 __u32 *off); 215 struct btf *btf_get_from_fd(int btf_fd, struct btf *base_btf); 216 217 struct btf_ext_info { 218 /* 219 * info points to the individual info section (e.g. func_info and 220 * line_info) from the .BTF.ext. It does not include the __u32 rec_size. 221 */ 222 void *info; 223 __u32 rec_size; 224 __u32 len; 225 }; 226 227 #define for_each_btf_ext_sec(seg, sec) \ 228 for (sec = (seg)->info; \ 229 (void *)sec < (seg)->info + (seg)->len; \ 230 sec = (void *)sec + sizeof(struct btf_ext_info_sec) + \ 231 (seg)->rec_size * sec->num_info) 232 233 #define for_each_btf_ext_rec(seg, sec, i, rec) \ 234 for (i = 0, rec = (void *)&(sec)->data; \ 235 i < (sec)->num_info; \ 236 i++, rec = (void *)rec + (seg)->rec_size) 237 238 /* 239 * The .BTF.ext ELF section layout defined as 240 * struct btf_ext_header 241 * func_info subsection 242 * 243 * The func_info subsection layout: 244 * record size for struct bpf_func_info in the func_info subsection 245 * struct btf_sec_func_info for section #1 246 * a list of bpf_func_info records for section #1 247 * where struct bpf_func_info mimics one in include/uapi/linux/bpf.h 248 * but may not be identical 249 * struct btf_sec_func_info for section #2 250 * a list of bpf_func_info records for section #2 251 * ...... 252 * 253 * Note that the bpf_func_info record size in .BTF.ext may not 254 * be the same as the one defined in include/uapi/linux/bpf.h. 255 * The loader should ensure that record_size meets minimum 256 * requirement and pass the record as is to the kernel. The 257 * kernel will handle the func_info properly based on its contents. 258 */ 259 struct btf_ext_header { 260 __u16 magic; 261 __u8 version; 262 __u8 flags; 263 __u32 hdr_len; 264 265 /* All offsets are in bytes relative to the end of this header */ 266 __u32 func_info_off; 267 __u32 func_info_len; 268 __u32 line_info_off; 269 __u32 line_info_len; 270 271 /* optional part of .BTF.ext header */ 272 __u32 core_relo_off; 273 __u32 core_relo_len; 274 }; 275 276 struct btf_ext { 277 union { 278 struct btf_ext_header *hdr; 279 void *data; 280 }; 281 struct btf_ext_info func_info; 282 struct btf_ext_info line_info; 283 struct btf_ext_info core_relo_info; 284 __u32 data_size; 285 }; 286 287 struct btf_ext_info_sec { 288 __u32 sec_name_off; 289 __u32 num_info; 290 /* Followed by num_info * record_size number of bytes */ 291 __u8 data[]; 292 }; 293 294 /* The minimum bpf_func_info checked by the loader */ 295 struct bpf_func_info_min { 296 __u32 insn_off; 297 __u32 type_id; 298 }; 299 300 /* The minimum bpf_line_info checked by the loader */ 301 struct bpf_line_info_min { 302 __u32 insn_off; 303 __u32 file_name_off; 304 __u32 line_off; 305 __u32 line_col; 306 }; 307 308 /* bpf_core_relo_kind encodes which aspect of captured field/type/enum value 309 * has to be adjusted by relocations. 310 */ 311 enum bpf_core_relo_kind { 312 BPF_FIELD_BYTE_OFFSET = 0, /* field byte offset */ 313 BPF_FIELD_BYTE_SIZE = 1, /* field size in bytes */ 314 BPF_FIELD_EXISTS = 2, /* field existence in target kernel */ 315 BPF_FIELD_SIGNED = 3, /* field signedness (0 - unsigned, 1 - signed) */ 316 BPF_FIELD_LSHIFT_U64 = 4, /* bitfield-specific left bitshift */ 317 BPF_FIELD_RSHIFT_U64 = 5, /* bitfield-specific right bitshift */ 318 BPF_TYPE_ID_LOCAL = 6, /* type ID in local BPF object */ 319 BPF_TYPE_ID_TARGET = 7, /* type ID in target kernel */ 320 BPF_TYPE_EXISTS = 8, /* type existence in target kernel */ 321 BPF_TYPE_SIZE = 9, /* type size in bytes */ 322 BPF_ENUMVAL_EXISTS = 10, /* enum value existence in target kernel */ 323 BPF_ENUMVAL_VALUE = 11, /* enum value integer value */ 324 }; 325 326 /* The minimum bpf_core_relo checked by the loader 327 * 328 * CO-RE relocation captures the following data: 329 * - insn_off - instruction offset (in bytes) within a BPF program that needs 330 * its insn->imm field to be relocated with actual field info; 331 * - type_id - BTF type ID of the "root" (containing) entity of a relocatable 332 * type or field; 333 * - access_str_off - offset into corresponding .BTF string section. String 334 * interpretation depends on specific relocation kind: 335 * - for field-based relocations, string encodes an accessed field using 336 * a sequence of field and array indices, separated by colon (:). It's 337 * conceptually very close to LLVM's getelementptr ([0]) instruction's 338 * arguments for identifying offset to a field. 339 * - for type-based relocations, strings is expected to be just "0"; 340 * - for enum value-based relocations, string contains an index of enum 341 * value within its enum type; 342 * 343 * Example to provide a better feel. 344 * 345 * struct sample { 346 * int a; 347 * struct { 348 * int b[10]; 349 * }; 350 * }; 351 * 352 * struct sample *s = ...; 353 * int x = &s->a; // encoded as "0:0" (a is field #0) 354 * int y = &s->b[5]; // encoded as "0:1:0:5" (anon struct is field #1, 355 * // b is field #0 inside anon struct, accessing elem #5) 356 * int z = &s[10]->b; // encoded as "10:1" (ptr is used as an array) 357 * 358 * type_id for all relocs in this example will capture BTF type id of 359 * `struct sample`. 360 * 361 * Such relocation is emitted when using __builtin_preserve_access_index() 362 * Clang built-in, passing expression that captures field address, e.g.: 363 * 364 * bpf_probe_read(&dst, sizeof(dst), 365 * __builtin_preserve_access_index(&src->a.b.c)); 366 * 367 * In this case Clang will emit field relocation recording necessary data to 368 * be able to find offset of embedded `a.b.c` field within `src` struct. 369 * 370 * [0] https://llvm.org/docs/LangRef.html#getelementptr-instruction 371 */ 372 struct bpf_core_relo { 373 __u32 insn_off; 374 __u32 type_id; 375 __u32 access_str_off; 376 enum bpf_core_relo_kind kind; 377 }; 378 379 typedef int (*type_id_visit_fn)(__u32 *type_id, void *ctx); 380 typedef int (*str_off_visit_fn)(__u32 *str_off, void *ctx); 381 int btf_type_visit_type_ids(struct btf_type *t, type_id_visit_fn visit, void *ctx); 382 int btf_type_visit_str_offs(struct btf_type *t, str_off_visit_fn visit, void *ctx); 383 int btf_ext_visit_type_ids(struct btf_ext *btf_ext, type_id_visit_fn visit, void *ctx); 384 int btf_ext_visit_str_offs(struct btf_ext *btf_ext, str_off_visit_fn visit, void *ctx); 385 386 #endif /* __LIBBPF_LIBBPF_INTERNAL_H */ 387