1/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
2/* Copyright (c) 2018 Facebook */
3#ifndef __LINUX_BTF_H__
4#define __LINUX_BTF_H__
5
6#include <linux/types.h>
7
8#define BTF_MAGIC 0xeB9F
9#define BTF_VERSION 1
10
11/*
12 * BTF layout section consists of a struct btf_layout for each known
13 * kind at BTF encoding time.
14 */
15struct btf_layout {
16 __u8 info_sz; /* size of singular element after btf_type */
17 __u8 elem_sz; /* size of each of btf_vlen(t) elements */
18 __u16 flags; /* currently unused */
19};
20
21struct btf_header {
22 __u16 magic;
23 __u8 version;
24 __u8 flags;
25 __u32 hdr_len;
26
27 /* All offsets are in bytes relative to the end of this header */
28 __u32 type_off; /* offset of type section */
29 __u32 type_len; /* length of type section */
30 __u32 str_off; /* offset of string section */
31 __u32 str_len; /* length of string section */
32 __u32 layout_off; /* offset of layout section */
33 __u32 layout_len; /* length of layout section */
34};
35
36enum btf_max {
37 /* Max possible kind */
38 BTF_MAX_KIND = 0x0000007f,
39 /* Max # of type identifier */
40 BTF_MAX_TYPE = 0x000fffff,
41 /* Max offset into the string section */
42 BTF_MAX_NAME_OFFSET = 0x00ffffff,
43 /* Max # of struct/union/enum members or func args */
44 BTF_MAX_VLEN = 0x00ffffff,
45};
46
47struct btf_type {
48 __u32 name_off;
49 /* "info" bits arrangement
50 * bits 0-23: vlen (e.g. # of struct's members)
51 * bits 24-30: kind (e.g. int, ptr, array...etc)
52 * bit 31: kind_flag, currently used by
53 * struct, union, enum, fwd, enum64,
54 * decl_tag and type_tag
55 */
56 __u32 info;
57 /* "size" is used by INT, ENUM, STRUCT, UNION, DATASEC and ENUM64.
58 * "size" tells the size of the type it is describing.
59 *
60 * "type" is used by PTR, TYPEDEF, VOLATILE, CONST, RESTRICT,
61 * FUNC, FUNC_PROTO, VAR, DECL_TAG and TYPE_TAG.
62 * "type" is a type_id referring to another type.
63 */
64 union {
65 __u32 size;
66 __u32 type;
67 };
68};
69
70#define BTF_INFO_KIND(info) (((info) >> 24) & 0x7f)
71#define BTF_INFO_VLEN(info) ((info) & 0xffffff)
72#define BTF_INFO_KFLAG(info) ((info) >> 31)
73
74enum {
75 BTF_KIND_UNKN = 0, /* Unknown */
76 BTF_KIND_INT = 1, /* Integer */
77 BTF_KIND_PTR = 2, /* Pointer */
78 BTF_KIND_ARRAY = 3, /* Array */
79 BTF_KIND_STRUCT = 4, /* Struct */
80 BTF_KIND_UNION = 5, /* Union */
81 BTF_KIND_ENUM = 6, /* Enumeration up to 32-bit values */
82 BTF_KIND_FWD = 7, /* Forward */
83 BTF_KIND_TYPEDEF = 8, /* Typedef */
84 BTF_KIND_VOLATILE = 9, /* Volatile */
85 BTF_KIND_CONST = 10, /* Const */
86 BTF_KIND_RESTRICT = 11, /* Restrict */
87 BTF_KIND_FUNC = 12, /* Function */
88 BTF_KIND_FUNC_PROTO = 13, /* Function Proto */
89 BTF_KIND_VAR = 14, /* Variable */
90 BTF_KIND_DATASEC = 15, /* Section */
91 BTF_KIND_FLOAT = 16, /* Floating point */
92 BTF_KIND_DECL_TAG = 17, /* Decl Tag */
93 BTF_KIND_TYPE_TAG = 18, /* Type Tag */
94 BTF_KIND_ENUM64 = 19, /* Enumeration up to 64-bit values */
95
96 NR_BTF_KINDS,
97 BTF_KIND_MAX = NR_BTF_KINDS - 1,
98};
99
100/* For some specific BTF_KIND, "struct btf_type" is immediately
101 * followed by extra data.
102 */
103
104/* BTF_KIND_INT is followed by a u32 and the following
105 * is the 32 bits arrangement:
106 */
107#define BTF_INT_ENCODING(VAL) (((VAL) & 0x0f000000) >> 24)
108#define BTF_INT_OFFSET(VAL) (((VAL) & 0x00ff0000) >> 16)
109#define BTF_INT_BITS(VAL) ((VAL) & 0x000000ff)
110
111/* Attributes stored in the BTF_INT_ENCODING */
112#define BTF_INT_SIGNED (1 << 0)
113#define BTF_INT_CHAR (1 << 1)
114#define BTF_INT_BOOL (1 << 2)
115
116/* BTF_KIND_ENUM is followed by multiple "struct btf_enum".
117 * The exact number of btf_enum is stored in the vlen (of the
118 * info in "struct btf_type").
119 */
120struct btf_enum {
121 __u32 name_off;
122 __s32 val;
123};
124
125/* BTF_KIND_ARRAY is followed by one "struct btf_array" */
126struct btf_array {
127 __u32 type;
128 __u32 index_type;
129 __u32 nelems;
130};
131
132/* BTF_KIND_STRUCT and BTF_KIND_UNION are followed
133 * by multiple "struct btf_member". The exact number
134 * of btf_member is stored in the vlen (of the info in
135 * "struct btf_type").
136 */
137struct btf_member {
138 __u32 name_off;
139 __u32 type;
140 /* If the type info kind_flag is set, the btf_member offset
141 * contains both member bitfield size and bit offset. The
142 * bitfield size is set for bitfield members. If the type
143 * info kind_flag is not set, the offset contains only bit
144 * offset.
145 */
146 __u32 offset;
147};
148
149/* If the struct/union type info kind_flag is set, the
150 * following two macros are used to access bitfield_size
151 * and bit_offset from btf_member.offset.
152 */
153#define BTF_MEMBER_BITFIELD_SIZE(val) ((val) >> 24)
154#define BTF_MEMBER_BIT_OFFSET(val) ((val) & 0xffffff)
155
156/* BTF_KIND_FUNC_PROTO is followed by multiple "struct btf_param".
157 * The exact number of btf_param is stored in the vlen (of the
158 * info in "struct btf_type").
159 */
160struct btf_param {
161 __u32 name_off;
162 __u32 type;
163};
164
165enum {
166 BTF_VAR_STATIC = 0,
167 BTF_VAR_GLOBAL_ALLOCATED = 1,
168 BTF_VAR_GLOBAL_EXTERN = 2,
169};
170
171enum btf_func_linkage {
172 BTF_FUNC_STATIC = 0,
173 BTF_FUNC_GLOBAL = 1,
174 BTF_FUNC_EXTERN = 2,
175};
176
177/* BTF_KIND_VAR is followed by a single "struct btf_var" to describe
178 * additional information related to the variable such as its linkage.
179 */
180struct btf_var {
181 __u32 linkage;
182};
183
184/* BTF_KIND_DATASEC is followed by multiple "struct btf_var_secinfo"
185 * to describe all BTF_KIND_VAR types it contains along with it's
186 * in-section offset as well as size.
187 */
188struct btf_var_secinfo {
189 __u32 type;
190 __u32 offset;
191 __u32 size;
192};
193
194/* BTF_KIND_DECL_TAG is followed by a single "struct btf_decl_tag" to describe
195 * additional information related to the tag applied location.
196 * If component_idx == -1, the tag is applied to a struct, union,
197 * variable or function. Otherwise, it is applied to a struct/union
198 * member or a func argument, and component_idx indicates which member
199 * or argument (0 ... vlen-1).
200 */
201struct btf_decl_tag {
202 __s32 component_idx;
203};
204
205/* BTF_KIND_ENUM64 is followed by multiple "struct btf_enum64".
206 * The exact number of btf_enum64 is stored in the vlen (of the
207 * info in "struct btf_type").
208 */
209struct btf_enum64 {
210 __u32 name_off;
211 __u32 val_lo32;
212 __u32 val_hi32;
213};
214
215#endif /* __LINUX_BTF_H__ */