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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 and fwd
40 */
41 __u32 info;
42 /* "size" is used by INT, ENUM, STRUCT, UNION and DATASEC.
43 * "size" tells the size of the type it is describing.
44 *
45 * "type" is used by PTR, TYPEDEF, VOLATILE, CONST, RESTRICT,
46 * FUNC, FUNC_PROTO, VAR, DECL_TAG and TYPE_TAG.
47 * "type" is a type_id referring to another type.
48 */
49 union {
50 __u32 size;
51 __u32 type;
52 };
53};
54
55#define BTF_INFO_KIND(info) (((info) >> 24) & 0x1f)
56#define BTF_INFO_VLEN(info) ((info) & 0xffff)
57#define BTF_INFO_KFLAG(info) ((info) >> 31)
58
59enum {
60 BTF_KIND_UNKN = 0, /* Unknown */
61 BTF_KIND_INT = 1, /* Integer */
62 BTF_KIND_PTR = 2, /* Pointer */
63 BTF_KIND_ARRAY = 3, /* Array */
64 BTF_KIND_STRUCT = 4, /* Struct */
65 BTF_KIND_UNION = 5, /* Union */
66 BTF_KIND_ENUM = 6, /* Enumeration */
67 BTF_KIND_FWD = 7, /* Forward */
68 BTF_KIND_TYPEDEF = 8, /* Typedef */
69 BTF_KIND_VOLATILE = 9, /* Volatile */
70 BTF_KIND_CONST = 10, /* Const */
71 BTF_KIND_RESTRICT = 11, /* Restrict */
72 BTF_KIND_FUNC = 12, /* Function */
73 BTF_KIND_FUNC_PROTO = 13, /* Function Proto */
74 BTF_KIND_VAR = 14, /* Variable */
75 BTF_KIND_DATASEC = 15, /* Section */
76 BTF_KIND_FLOAT = 16, /* Floating point */
77 BTF_KIND_DECL_TAG = 17, /* Decl Tag */
78 BTF_KIND_TYPE_TAG = 18, /* Type Tag */
79
80 NR_BTF_KINDS,
81 BTF_KIND_MAX = NR_BTF_KINDS - 1,
82};
83
84/* For some specific BTF_KIND, "struct btf_type" is immediately
85 * followed by extra data.
86 */
87
88/* BTF_KIND_INT is followed by a u32 and the following
89 * is the 32 bits arrangement:
90 */
91#define BTF_INT_ENCODING(VAL) (((VAL) & 0x0f000000) >> 24)
92#define BTF_INT_OFFSET(VAL) (((VAL) & 0x00ff0000) >> 16)
93#define BTF_INT_BITS(VAL) ((VAL) & 0x000000ff)
94
95/* Attributes stored in the BTF_INT_ENCODING */
96#define BTF_INT_SIGNED (1 << 0)
97#define BTF_INT_CHAR (1 << 1)
98#define BTF_INT_BOOL (1 << 2)
99
100/* BTF_KIND_ENUM is followed by multiple "struct btf_enum".
101 * The exact number of btf_enum is stored in the vlen (of the
102 * info in "struct btf_type").
103 */
104struct btf_enum {
105 __u32 name_off;
106 __s32 val;
107};
108
109/* BTF_KIND_ARRAY is followed by one "struct btf_array" */
110struct btf_array {
111 __u32 type;
112 __u32 index_type;
113 __u32 nelems;
114};
115
116/* BTF_KIND_STRUCT and BTF_KIND_UNION are followed
117 * by multiple "struct btf_member". The exact number
118 * of btf_member is stored in the vlen (of the info in
119 * "struct btf_type").
120 */
121struct btf_member {
122 __u32 name_off;
123 __u32 type;
124 /* If the type info kind_flag is set, the btf_member offset
125 * contains both member bitfield size and bit offset. The
126 * bitfield size is set for bitfield members. If the type
127 * info kind_flag is not set, the offset contains only bit
128 * offset.
129 */
130 __u32 offset;
131};
132
133/* If the struct/union type info kind_flag is set, the
134 * following two macros are used to access bitfield_size
135 * and bit_offset from btf_member.offset.
136 */
137#define BTF_MEMBER_BITFIELD_SIZE(val) ((val) >> 24)
138#define BTF_MEMBER_BIT_OFFSET(val) ((val) & 0xffffff)
139
140/* BTF_KIND_FUNC_PROTO is followed by multiple "struct btf_param".
141 * The exact number of btf_param is stored in the vlen (of the
142 * info in "struct btf_type").
143 */
144struct btf_param {
145 __u32 name_off;
146 __u32 type;
147};
148
149enum {
150 BTF_VAR_STATIC = 0,
151 BTF_VAR_GLOBAL_ALLOCATED = 1,
152 BTF_VAR_GLOBAL_EXTERN = 2,
153};
154
155enum btf_func_linkage {
156 BTF_FUNC_STATIC = 0,
157 BTF_FUNC_GLOBAL = 1,
158 BTF_FUNC_EXTERN = 2,
159};
160
161/* BTF_KIND_VAR is followed by a single "struct btf_var" to describe
162 * additional information related to the variable such as its linkage.
163 */
164struct btf_var {
165 __u32 linkage;
166};
167
168/* BTF_KIND_DATASEC is followed by multiple "struct btf_var_secinfo"
169 * to describe all BTF_KIND_VAR types it contains along with it's
170 * in-section offset as well as size.
171 */
172struct btf_var_secinfo {
173 __u32 type;
174 __u32 offset;
175 __u32 size;
176};
177
178/* BTF_KIND_DECL_TAG is followed by a single "struct btf_decl_tag" to describe
179 * additional information related to the tag applied location.
180 * If component_idx == -1, the tag is applied to a struct, union,
181 * variable or function. Otherwise, it is applied to a struct/union
182 * member or a func argument, and component_idx indicates which member
183 * or argument (0 ... vlen-1).
184 */
185struct btf_decl_tag {
186 __s32 component_idx;
187};
188
189#endif /* _UAPI__LINUX_BTF_H__ */