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 */ 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); 111 112 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