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/* Symbol versioning is different between static and shared library.
 38 * Properly versioned symbols are needed for shared library, but
 39 * only the symbol of the new version is needed for static library.
 40 */
 41#ifdef SHARED
 42# define COMPAT_VERSION(internal_name, api_name, version) \
 43	asm(".symver " #internal_name "," #api_name "@" #version);
 44# define DEFAULT_VERSION(internal_name, api_name, version) \
 45	asm(".symver " #internal_name "," #api_name "@@" #version);
 46#else
 47# define COMPAT_VERSION(internal_name, api_name, version)
 48# define DEFAULT_VERSION(internal_name, api_name, version) \
 49	extern typeof(internal_name) api_name \
 50	__attribute__((alias(#internal_name)));
 51#endif
 52
 53extern void libbpf_print(enum libbpf_print_level level,
 54			 const char *format, ...)
 55	__attribute__((format(printf, 2, 3)));
 56
 57#define __pr(level, fmt, ...)	\
 58do {				\
 59	libbpf_print(level, "libbpf: " fmt, ##__VA_ARGS__);	\
 60} while (0)
 61
 62#define pr_warning(fmt, ...)	__pr(LIBBPF_WARN, fmt, ##__VA_ARGS__)
 63#define pr_info(fmt, ...)	__pr(LIBBPF_INFO, fmt, ##__VA_ARGS__)
 64#define pr_debug(fmt, ...)	__pr(LIBBPF_DEBUG, fmt, ##__VA_ARGS__)
 65
 66int libbpf__load_raw_btf(const char *raw_types, size_t types_len,
 67			 const char *str_sec, size_t str_len);
 68
 69struct btf_ext_info {
 70	/*
 71	 * info points to the individual info section (e.g. func_info and
 72	 * line_info) from the .BTF.ext. It does not include the __u32 rec_size.
 73	 */
 74	void *info;
 75	__u32 rec_size;
 76	__u32 len;
 77};
 78
 79#define for_each_btf_ext_sec(seg, sec)					\
 80	for (sec = (seg)->info;						\
 81	     (void *)sec < (seg)->info + (seg)->len;			\
 82	     sec = (void *)sec + sizeof(struct btf_ext_info_sec) +	\
 83		   (seg)->rec_size * sec->num_info)
 84
 85#define for_each_btf_ext_rec(seg, sec, i, rec)				\
 86	for (i = 0, rec = (void *)&(sec)->data;				\
 87	     i < (sec)->num_info;					\
 88	     i++, rec = (void *)rec + (seg)->rec_size)
 89
 90struct btf_ext {
 91	union {
 92		struct btf_ext_header *hdr;
 93		void *data;
 94	};
 95	struct btf_ext_info func_info;
 96	struct btf_ext_info line_info;
 97	struct btf_ext_info offset_reloc_info;
 98	__u32 data_size;
 99};
100
101struct btf_ext_info_sec {
102	__u32	sec_name_off;
103	__u32	num_info;
104	/* Followed by num_info * record_size number of bytes */
105	__u8	data[0];
106};
107
108/* The minimum bpf_func_info checked by the loader */
109struct bpf_func_info_min {
110	__u32   insn_off;
111	__u32   type_id;
112};
113
114/* The minimum bpf_line_info checked by the loader */
115struct bpf_line_info_min {
116	__u32	insn_off;
117	__u32	file_name_off;
118	__u32	line_off;
119	__u32	line_col;
120};
121
122/* The minimum bpf_offset_reloc checked by the loader
123 *
124 * Offset relocation captures the following data:
125 * - insn_off - instruction offset (in bytes) within a BPF program that needs
126 *   its insn->imm field to be relocated with actual offset;
127 * - type_id - BTF type ID of the "root" (containing) entity of a relocatable
128 *   offset;
129 * - access_str_off - offset into corresponding .BTF string section. String
130 *   itself encodes an accessed field using a sequence of field and array
131 *   indicies, separated by colon (:). It's conceptually very close to LLVM's
132 *   getelementptr ([0]) instruction's arguments for identifying offset to 
133 *   a field.
134 *
135 * Example to provide a better feel.
136 *
137 *   struct sample {
138 *       int a;
139 *       struct {
140 *           int b[10];
141 *       };
142 *   };
143 *
144 *   struct sample *s = ...;
145 *   int x = &s->a;     // encoded as "0:0" (a is field #0)
146 *   int y = &s->b[5];  // encoded as "0:1:0:5" (anon struct is field #1, 
147 *                      // b is field #0 inside anon struct, accessing elem #5)
148 *   int z = &s[10]->b; // encoded as "10:1" (ptr is used as an array)
149 *
150 * type_id for all relocs in this example  will capture BTF type id of
151 * `struct sample`.
152 *
153 * Such relocation is emitted when using __builtin_preserve_access_index()
154 * Clang built-in, passing expression that captures field address, e.g.:
155 *
156 * bpf_probe_read(&dst, sizeof(dst),
157 *		  __builtin_preserve_access_index(&src->a.b.c));
158 *
159 * In this case Clang will emit offset relocation recording necessary data to
160 * be able to find offset of embedded `a.b.c` field within `src` struct.
161 *
162 *   [0] https://llvm.org/docs/LangRef.html#getelementptr-instruction
163 */
164struct bpf_offset_reloc {
165	__u32   insn_off;
166	__u32   type_id;
167	__u32   access_str_off;
168};
169
170#endif /* __LIBBPF_LIBBPF_INTERNAL_H */