1/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
2/* Copyright (c) 2018 Facebook */
3#ifndef _UAPI__LINUX_BTF_H__
4#define _UAPI__LINUX_BTF_H__
5
6#include <linux/types.h>
7
8#define BTF_MAGIC 0xeB9F
9#define BTF_VERSION 1
10
11struct btf_header {
12 __u16 magic;
13 __u8 version;
14 __u8 flags;
15 __u32 hdr_len;
16
17 /* All offsets are in bytes relative to the end of this header */
18 __u32 type_off; /* offset of type section */
19 __u32 type_len; /* length of type section */
20 __u32 str_off; /* offset of string section */
21 __u32 str_len; /* length of string section */
22};
23
24/* Max # of type identifier */
25#define BTF_MAX_TYPE 0x000fffff
26/* Max offset into the string section */
27#define BTF_MAX_NAME_OFFSET 0x00ffffff
28/* Max # of struct/union/enum members or func args */
29#define BTF_MAX_VLEN 0xffff
30
31struct btf_type {
32 __u32 name_off;
33 /* "info" bits arrangement
34 * bits 0-15: vlen (e.g. # of struct's members)
35 * bits 16-23: unused
36 * bits 24-28: kind (e.g. int, ptr, array...etc)
37 * bits 29-30: unused
38 * bit 31: kind_flag, currently used by
39 * struct, union, enum, fwd, enum64,
40 * decl_tag and type_tag
41 */
42 __u32 info;
43 /* "size" is used by INT, ENUM, STRUCT, UNION, DATASEC and ENUM64.
44 * "size" tells the size of the type it is describing.
45 *
46 * "type" is used by PTR, TYPEDEF, VOLATILE, CONST, RESTRICT,
47 * FUNC, FUNC_PROTO, VAR, DECL_TAG and TYPE_TAG.
48 * "type" is a type_id referring to another type.
49 */
50 union {
51 __u32 size;
52 __u32 type;
53 };
54};
55
56#define BTF_INFO_KIND(info) (((info) >> 24) & 0x1f)
57#define BTF_INFO_VLEN(info) ((info) & 0xffff)
58#define BTF_INFO_KFLAG(info) ((info) >> 31)
59
60enum {
61 BTF_KIND_UNKN = 0, /* Unknown */
62 BTF_KIND_INT = 1, /* Integer */
63 BTF_KIND_PTR = 2, /* Pointer */
64 BTF_KIND_ARRAY = 3, /* Array */
65 BTF_KIND_STRUCT = 4, /* Struct */
66 BTF_KIND_UNION = 5, /* Union */
67 BTF_KIND_ENUM = 6, /* Enumeration up to 32-bit values */
68 BTF_KIND_FWD = 7, /* Forward */
69 BTF_KIND_TYPEDEF = 8, /* Typedef */
70 BTF_KIND_VOLATILE = 9, /* Volatile */
71 BTF_KIND_CONST = 10, /* Const */
72 BTF_KIND_RESTRICT = 11, /* Restrict */
73 BTF_KIND_FUNC = 12, /* Function */
74 BTF_KIND_FUNC_PROTO = 13, /* Function Proto */
75 BTF_KIND_VAR = 14, /* Variable */
76 BTF_KIND_DATASEC = 15, /* Section */
77 BTF_KIND_FLOAT = 16, /* Floating point */
78 BTF_KIND_DECL_TAG = 17, /* Decl Tag */
79 BTF_KIND_TYPE_TAG = 18, /* Type Tag */
80 BTF_KIND_ENUM64 = 19, /* Enumeration up to 64-bit values */
81
82 NR_BTF_KINDS,
83 BTF_KIND_MAX = NR_BTF_KINDS - 1,
84};
85
86/* For some specific BTF_KIND, "struct btf_type" is immediately
87 * followed by extra data.
88 */
89
90/* BTF_KIND_INT is followed by a u32 and the following
91 * is the 32 bits arrangement:
92 */
93#define BTF_INT_ENCODING(VAL) (((VAL) & 0x0f000000) >> 24)
94#define BTF_INT_OFFSET(VAL) (((VAL) & 0x00ff0000) >> 16)
95#define BTF_INT_BITS(VAL) ((VAL) & 0x000000ff)
96
97/* Attributes stored in the BTF_INT_ENCODING */
98#define BTF_INT_SIGNED (1 << 0)
99#define BTF_INT_CHAR (1 << 1)
100#define BTF_INT_BOOL (1 << 2)
101
102/* BTF_KIND_ENUM is followed by multiple "struct btf_enum".
103 * The exact number of btf_enum is stored in the vlen (of the
104 * info in "struct btf_type").
105 */
106struct btf_enum {
107 __u32 name_off;
108 __s32 val;
109};
110
111/* BTF_KIND_ARRAY is followed by one "struct btf_array" */
112struct btf_array {
113 __u32 type;
114 __u32 index_type;
115 __u32 nelems;
116};
117
118/* BTF_KIND_STRUCT and BTF_KIND_UNION are followed
119 * by multiple "struct btf_member". The exact number
120 * of btf_member is stored in the vlen (of the info in
121 * "struct btf_type").
122 */
123struct btf_member {
124 __u32 name_off;
125 __u32 type;
126 /* If the type info kind_flag is set, the btf_member offset
127 * contains both member bitfield size and bit offset. The
128 * bitfield size is set for bitfield members. If the type
129 * info kind_flag is not set, the offset contains only bit
130 * offset.
131 */
132 __u32 offset;
133};
134
135/* If the struct/union type info kind_flag is set, the
136 * following two macros are used to access bitfield_size
137 * and bit_offset from btf_member.offset.
138 */
139#define BTF_MEMBER_BITFIELD_SIZE(val) ((val) >> 24)
140#define BTF_MEMBER_BIT_OFFSET(val) ((val) & 0xffffff)
141
142/* BTF_KIND_FUNC_PROTO is followed by multiple "struct btf_param".
143 * The exact number of btf_param is stored in the vlen (of the
144 * info in "struct btf_type").
145 */
146struct btf_param {
147 __u32 name_off;
148 __u32 type;
149};
150
151enum {
152 BTF_VAR_STATIC = 0,
153 BTF_VAR_GLOBAL_ALLOCATED = 1,
154 BTF_VAR_GLOBAL_EXTERN = 2,
155};
156
157enum btf_func_linkage {
158 BTF_FUNC_STATIC = 0,
159 BTF_FUNC_GLOBAL = 1,
160 BTF_FUNC_EXTERN = 2,
161};
162
163/* BTF_KIND_VAR is followed by a single "struct btf_var" to describe
164 * additional information related to the variable such as its linkage.
165 */
166struct btf_var {
167 __u32 linkage;
168};
169
170/* BTF_KIND_DATASEC is followed by multiple "struct btf_var_secinfo"
171 * to describe all BTF_KIND_VAR types it contains along with it's
172 * in-section offset as well as size.
173 */
174struct btf_var_secinfo {
175 __u32 type;
176 __u32 offset;
177 __u32 size;
178};
179
180/* BTF_KIND_DECL_TAG is followed by a single "struct btf_decl_tag" to describe
181 * additional information related to the tag applied location.
182 * If component_idx == -1, the tag is applied to a struct, union,
183 * variable or function. Otherwise, it is applied to a struct/union
184 * member or a func argument, and component_idx indicates which member
185 * or argument (0 ... vlen-1).
186 */
187struct btf_decl_tag {
188 __s32 component_idx;
189};
190
191/* BTF_KIND_ENUM64 is followed by multiple "struct btf_enum64".
192 * The exact number of btf_enum64 is stored in the vlen (of the
193 * info in "struct btf_type").
194 */
195struct btf_enum64 {
196 __u32 name_off;
197 __u32 val_lo32;
198 __u32 val_hi32;
199};
200
201#endif /* _UAPI__LINUX_BTF_H__ */
202

source code of linux/include/uapi/linux/btf.h

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