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