summaryrefslogtreecommitdiffstats
path: root/tools/lib/bpf/libbpf_internal.h
blob: 97ac17a64a58dde59adfedb34f0959c8b4c50215 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */

/*
 * Internal libbpf helpers.
 *
 * Copyright (c) 2019 Facebook
 */

#ifndef __LIBBPF_LIBBPF_INTERNAL_H
#define __LIBBPF_LIBBPF_INTERNAL_H

#include "libbpf.h"

#define BTF_INFO_ENC(kind, kind_flag, vlen) \
	((!!(kind_flag) << 31) | ((kind) << 24) | ((vlen) & BTF_MAX_VLEN))
#define BTF_TYPE_ENC(name, info, size_or_type) (name), (info), (size_or_type)
#define BTF_INT_ENC(encoding, bits_offset, nr_bits) \
	((encoding) << 24 | (bits_offset) << 16 | (nr_bits))
#define BTF_TYPE_INT_ENC(name, encoding, bits_offset, bits, sz) \
	BTF_TYPE_ENC(name, BTF_INFO_ENC(BTF_KIND_INT, 0, 0), sz), \
	BTF_INT_ENC(encoding, bits_offset, bits)
#define BTF_MEMBER_ENC(name, type, bits_offset) (name), (type), (bits_offset)
#define BTF_PARAM_ENC(name, type) (name), (type)
#define BTF_VAR_SECINFO_ENC(type, offset, size) (type), (offset), (size)

#ifndef min
# define min(x, y) ((x) < (y) ? (x) : (y))
#endif
#ifndef max
# define max(x, y) ((x) < (y) ? (y) : (x))
#endif
#ifndef offsetofend
# define offsetofend(TYPE, FIELD) \
	(offsetof(TYPE, FIELD) + sizeof(((TYPE *)0)->FIELD))
#endif

/* Symbol versioning is different between static and shared library.
 * Properly versioned symbols are needed for shared library, but
 * only the symbol of the new version is needed for static library.
 */
#ifdef SHARED
# define COMPAT_VERSION(internal_name, api_name, version) \
	asm(".symver " #internal_name "," #api_name "@" #version);
# define DEFAULT_VERSION(internal_name, api_name, version) \
	asm(".symver " #internal_name "," #api_name "@@" #version);
#else
# define COMPAT_VERSION(internal_name, api_name, version)
# define DEFAULT_VERSION(internal_name, api_name, version) \
	extern typeof(internal_name) api_name \
	__attribute__((alias(#internal_name)));
#endif

extern void libbpf_print(enum libbpf_print_level level,
			 const char *format, ...)
	__attribute__((format(printf, 2, 3)));

#define __pr(level, fmt, ...)	\
do {				\
	libbpf_print(level, "libbpf: " fmt, ##__VA_ARGS__);	\
} while (0)

#define pr_warn(fmt, ...)	__pr(LIBBPF_WARN, fmt, ##__VA_ARGS__)
#define pr_info(fmt, ...)	__pr(LIBBPF_INFO, fmt, ##__VA_ARGS__)
#define pr_debug(fmt, ...)	__pr(LIBBPF_DEBUG, fmt, ##__VA_ARGS__)

static inline bool libbpf_validate_opts(const char *opts,
					size_t opts_sz, size_t user_sz,
					const char *type_name)
{
	if (user_sz < sizeof(size_t)) {
		pr_warn("%s size (%zu) is too small\n", type_name, user_sz);
		return false;
	}
	if (user_sz > opts_sz) {
		size_t i;

		for (i = opts_sz; i < user_sz; i++) {
			if (opts[i]) {
				pr_warn("%s has non-zero extra bytes",
					type_name);
				return false;
			}
		}
	}
	return true;
}

#define OPTS_VALID(opts, type)						      \
	(!(opts) || libbpf_validate_opts((const char *)opts,		      \
					 offsetofend(struct type,	      \
						     type##__last_field),     \
					 (opts)->sz, #type))
#define OPTS_HAS(opts, field) \
	((opts) && opts->sz >= offsetofend(typeof(*(opts)), field))
#define OPTS_GET(opts, field, fallback_value) \
	(OPTS_HAS(opts, field) ? (opts)->field : fallback_value)

int libbpf__load_raw_btf(const char *raw_types, size_t types_len,
			 const char *str_sec, size_t str_len);

struct btf_ext_info {
	/*
	 * info points to the individual info section (e.g. func_info and
	 * line_info) from the .BTF.ext. It does not include the __u32 rec_size.
	 */
	void *info;
	__u32 rec_size;
	__u32 len;
};

#define for_each_btf_ext_sec(seg, sec)					\
	for (sec = (seg)->info;						\
	     (void *)sec < (seg)->info + (seg)->len;			\
	     sec = (void *)sec + sizeof(struct btf_ext_info_sec) +	\
		   (seg)->rec_size * sec->num_info)

#define for_each_btf_ext_rec(seg, sec, i, rec)				\
	for (i = 0, rec = (void *)&(sec)->data;				\
	     i < (sec)->num_info;					\
	     i++, rec = (void *)rec + (seg)->rec_size)

struct btf_ext {
	union {
		struct btf_ext_header *hdr;
		void *data;
	};
	struct btf_ext_info func_info;
	struct btf_ext_info line_info;
	struct btf_ext_info field_reloc_info;
	__u32 data_size;
};

struct btf_ext_info_sec {
	__u32	sec_name_off;
	__u32	num_info;
	/* Followed by num_info * record_size number of bytes */
	__u8	data[0];
};

/* The minimum bpf_func_info checked by the loader */
struct bpf_func_info_min {
	__u32   insn_off;
	__u32   type_id;
};

/* The minimum bpf_line_info checked by the loader */
struct bpf_line_info_min {
	__u32	insn_off;
	__u32	file_name_off;
	__u32	line_off;
	__u32	line_col;
};

/* bpf_field_info_kind encodes which aspect of captured field has to be
 * adjusted by relocations. Currently supported values are:
 *   - BPF_FIELD_BYTE_OFFSET: field offset (in bytes);
 *   - BPF_FIELD_EXISTS: field existence (1, if field exists; 0, otherwise);
 */
enum bpf_field_info_kind {
	BPF_FIELD_BYTE_OFFSET = 0,	/* field byte offset */
	BPF_FIELD_BYTE_SIZE = 1,
	BPF_FIELD_EXISTS = 2,		/* field existence in target kernel */
	BPF_FIELD_SIGNED = 3,
	BPF_FIELD_LSHIFT_U64 = 4,
	BPF_FIELD_RSHIFT_U64 = 5,
};

/* The minimum bpf_field_reloc checked by the loader
 *
 * Field relocation captures the following data:
 * - insn_off - instruction offset (in bytes) within a BPF program that needs
 *   its insn->imm field to be relocated with actual field info;
 * - type_id - BTF type ID of the "root" (containing) entity of a relocatable
 *   field;
 * - access_str_off - offset into corresponding .BTF string section. String
 *   itself encodes an accessed field using a sequence of field and array
 *   indicies, separated by colon (:). It's conceptually very close to LLVM's
 *   getelementptr ([0]) instruction's arguments for identifying offset to 
 *   a field.
 *
 * Example to provide a better feel.
 *
 *   struct sample {
 *       int a;
 *       struct {
 *           int b[10];
 *       };
 *   };
 *
 *   struct sample *s = ...;
 *   int x = &s->a;     // encoded as "0:0" (a is field #0)
 *   int y = &s->b[5];  // encoded as "0:1:0:5" (anon struct is field #1, 
 *                      // b is field #0 inside anon struct, accessing elem #5)
 *   int z = &s[10]->b; // encoded as "10:1" (ptr is used as an array)
 *
 * type_id for all relocs in this example  will capture BTF type id of
 * `struct sample`.
 *
 * Such relocation is emitted when using __builtin_preserve_access_index()
 * Clang built-in, passing expression that captures field address, e.g.:
 *
 * bpf_probe_read(&dst, sizeof(dst),
 *		  __builtin_preserve_access_index(&src->a.b.c));
 *
 * In this case Clang will emit field relocation recording necessary data to
 * be able to find offset of embedded `a.b.c` field within `src` struct.
 *
 *   [0] https://llvm.org/docs/LangRef.html#getelementptr-instruction
 */
struct bpf_field_reloc {
	__u32   insn_off;
	__u32   type_id;
	__u32   access_str_off;
	enum bpf_field_info_kind kind;
};

#endif /* __LIBBPF_LIBBPF_INTERNAL_H */