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