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 "libbpf.h" 13 14 #define BTF_INFO_ENC(kind, kind_flag, vlen) \ 15 ((!!(kind_flag) << 31) | ((kind) << 24) | ((vlen) & BTF_MAX_VLEN)) 16 #define BTF_TYPE_ENC(name, info, size_or_type) (name), (info), (size_or_type) 17 #define BTF_INT_ENC(encoding, bits_offset, nr_bits) \ 18 ((encoding) << 24 | (bits_offset) << 16 | (nr_bits)) 19 #define BTF_TYPE_INT_ENC(name, encoding, bits_offset, bits, sz) \ 20 BTF_TYPE_ENC(name, BTF_INFO_ENC(BTF_KIND_INT, 0, 0), sz), \ 21 BTF_INT_ENC(encoding, bits_offset, bits) 22 #define BTF_MEMBER_ENC(name, type, bits_offset) (name), (type), (bits_offset) 23 #define BTF_PARAM_ENC(name, type) (name), (type) 24 #define BTF_VAR_SECINFO_ENC(type, offset, size) (type), (offset), (size) 25 26 #ifndef min 27 # define min(x, y) ((x) < (y) ? (x) : (y)) 28 #endif 29 #ifndef max 30 # define max(x, y) ((x) < (y) ? (y) : (x)) 31 #endif 32 #ifndef offsetofend 33 # define offsetofend(TYPE, FIELD) \ 34 (offsetof(TYPE, FIELD) + sizeof(((TYPE *)0)->FIELD)) 35 #endif 36 37 extern void libbpf_print(enum libbpf_print_level level, 38 const char *format, ...) 39 __attribute__((format(printf, 2, 3))); 40 41 #define __pr(level, fmt, ...) \ 42 do { \ 43 libbpf_print(level, "libbpf: " fmt, ##__VA_ARGS__); \ 44 } while (0) 45 46 #define pr_warning(fmt, ...) __pr(LIBBPF_WARN, fmt, ##__VA_ARGS__) 47 #define pr_info(fmt, ...) __pr(LIBBPF_INFO, fmt, ##__VA_ARGS__) 48 #define pr_debug(fmt, ...) __pr(LIBBPF_DEBUG, fmt, ##__VA_ARGS__) 49 50 int libbpf__load_raw_btf(const char *raw_types, size_t types_len, 51 const char *str_sec, size_t str_len); 52 53 struct btf_ext_info { 54 /* 55 * info points to the individual info section (e.g. func_info and 56 * line_info) from the .BTF.ext. It does not include the __u32 rec_size. 57 */ 58 void *info; 59 __u32 rec_size; 60 __u32 len; 61 }; 62 63 #define for_each_btf_ext_sec(seg, sec) \ 64 for (sec = (seg)->info; \ 65 (void *)sec < (seg)->info + (seg)->len; \ 66 sec = (void *)sec + sizeof(struct btf_ext_info_sec) + \ 67 (seg)->rec_size * sec->num_info) 68 69 #define for_each_btf_ext_rec(seg, sec, i, rec) \ 70 for (i = 0, rec = (void *)&(sec)->data; \ 71 i < (sec)->num_info; \ 72 i++, rec = (void *)rec + (seg)->rec_size) 73 74 struct btf_ext { 75 union { 76 struct btf_ext_header *hdr; 77 void *data; 78 }; 79 struct btf_ext_info func_info; 80 struct btf_ext_info line_info; 81 struct btf_ext_info offset_reloc_info; 82 __u32 data_size; 83 }; 84 85 struct btf_ext_info_sec { 86 __u32 sec_name_off; 87 __u32 num_info; 88 /* Followed by num_info * record_size number of bytes */ 89 __u8 data[0]; 90 }; 91 92 /* The minimum bpf_func_info checked by the loader */ 93 struct bpf_func_info_min { 94 __u32 insn_off; 95 __u32 type_id; 96 }; 97 98 /* The minimum bpf_line_info checked by the loader */ 99 struct bpf_line_info_min { 100 __u32 insn_off; 101 __u32 file_name_off; 102 __u32 line_off; 103 __u32 line_col; 104 }; 105 106 /* The minimum bpf_offset_reloc checked by the loader 107 * 108 * Offset relocation captures the following data: 109 * - insn_off - instruction offset (in bytes) within a BPF program that needs 110 * its insn->imm field to be relocated with actual offset; 111 * - type_id - BTF type ID of the "root" (containing) entity of a relocatable 112 * offset; 113 * - access_str_off - offset into corresponding .BTF string section. String 114 * itself encodes an accessed field using a sequence of field and array 115 * indicies, separated by colon (:). It's conceptually very close to LLVM's 116 * getelementptr ([0]) instruction's arguments for identifying offset to 117 * a field. 118 * 119 * Example to provide a better feel. 120 * 121 * struct sample { 122 * int a; 123 * struct { 124 * int b[10]; 125 * }; 126 * }; 127 * 128 * struct sample *s = ...; 129 * int x = &s->a; // encoded as "0:0" (a is field #0) 130 * int y = &s->b[5]; // encoded as "0:1:0:5" (anon struct is field #1, 131 * // b is field #0 inside anon struct, accessing elem #5) 132 * int z = &s[10]->b; // encoded as "10:1" (ptr is used as an array) 133 * 134 * type_id for all relocs in this example will capture BTF type id of 135 * `struct sample`. 136 * 137 * Such relocation is emitted when using __builtin_preserve_access_index() 138 * Clang built-in, passing expression that captures field address, e.g.: 139 * 140 * bpf_probe_read(&dst, sizeof(dst), 141 * __builtin_preserve_access_index(&src->a.b.c)); 142 * 143 * In this case Clang will emit offset relocation recording necessary data to 144 * be able to find offset of embedded `a.b.c` field within `src` struct. 145 * 146 * [0] https://llvm.org/docs/LangRef.html#getelementptr-instruction 147 */ 148 struct bpf_offset_reloc { 149 __u32 insn_off; 150 __u32 type_id; 151 __u32 access_str_off; 152 }; 153 154 #endif /* __LIBBPF_LIBBPF_INTERNAL_H */ 155