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
11 struct 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
31 struct 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 and enum64
40 */
41 __u32 info;
42 /* "size" is used by INT, ENUM, STRUCT, UNION, DATASEC and ENUM64.
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
59 enum {
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 up to 32-bit values */
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 BTF_KIND_ENUM64 = 19, /* Enumeration up to 64-bit values */
80
81 NR_BTF_KINDS,
82 BTF_KIND_MAX = NR_BTF_KINDS - 1,
83 };
84
85 /* For some specific BTF_KIND, "struct btf_type" is immediately
86 * followed by extra data.
87 */
88
89 /* BTF_KIND_INT is followed by a u32 and the following
90 * is the 32 bits arrangement:
91 */
92 #define BTF_INT_ENCODING(VAL) (((VAL) & 0x0f000000) >> 24)
93 #define BTF_INT_OFFSET(VAL) (((VAL) & 0x00ff0000) >> 16)
94 #define BTF_INT_BITS(VAL) ((VAL) & 0x000000ff)
95
96 /* Attributes stored in the BTF_INT_ENCODING */
97 #define BTF_INT_SIGNED (1 << 0)
98 #define BTF_INT_CHAR (1 << 1)
99 #define BTF_INT_BOOL (1 << 2)
100
101 /* BTF_KIND_ENUM is followed by multiple "struct btf_enum".
102 * The exact number of btf_enum is stored in the vlen (of the
103 * info in "struct btf_type").
104 */
105 struct btf_enum {
106 __u32 name_off;
107 __s32 val;
108 };
109
110 /* BTF_KIND_ARRAY is followed by one "struct btf_array" */
111 struct btf_array {
112 __u32 type;
113 __u32 index_type;
114 __u32 nelems;
115 };
116
117 /* BTF_KIND_STRUCT and BTF_KIND_UNION are followed
118 * by multiple "struct btf_member". The exact number
119 * of btf_member is stored in the vlen (of the info in
120 * "struct btf_type").
121 */
122 struct btf_member {
123 __u32 name_off;
124 __u32 type;
125 /* If the type info kind_flag is set, the btf_member offset
126 * contains both member bitfield size and bit offset. The
127 * bitfield size is set for bitfield members. If the type
128 * info kind_flag is not set, the offset contains only bit
129 * offset.
130 */
131 __u32 offset;
132 };
133
134 /* If the struct/union type info kind_flag is set, the
135 * following two macros are used to access bitfield_size
136 * and bit_offset from btf_member.offset.
137 */
138 #define BTF_MEMBER_BITFIELD_SIZE(val) ((val) >> 24)
139 #define BTF_MEMBER_BIT_OFFSET(val) ((val) & 0xffffff)
140
141 /* BTF_KIND_FUNC_PROTO is followed by multiple "struct btf_param".
142 * The exact number of btf_param is stored in the vlen (of the
143 * info in "struct btf_type").
144 */
145 struct btf_param {
146 __u32 name_off;
147 __u32 type;
148 };
149
150 enum {
151 BTF_VAR_STATIC = 0,
152 BTF_VAR_GLOBAL_ALLOCATED = 1,
153 BTF_VAR_GLOBAL_EXTERN = 2,
154 };
155
156 enum btf_func_linkage {
157 BTF_FUNC_STATIC = 0,
158 BTF_FUNC_GLOBAL = 1,
159 BTF_FUNC_EXTERN = 2,
160 };
161
162 /* BTF_KIND_VAR is followed by a single "struct btf_var" to describe
163 * additional information related to the variable such as its linkage.
164 */
165 struct btf_var {
166 __u32 linkage;
167 };
168
169 /* BTF_KIND_DATASEC is followed by multiple "struct btf_var_secinfo"
170 * to describe all BTF_KIND_VAR types it contains along with it's
171 * in-section offset as well as size.
172 */
173 struct btf_var_secinfo {
174 __u32 type;
175 __u32 offset;
176 __u32 size;
177 };
178
179 /* BTF_KIND_DECL_TAG is followed by a single "struct btf_decl_tag" to describe
180 * additional information related to the tag applied location.
181 * If component_idx == -1, the tag is applied to a struct, union,
182 * variable or function. Otherwise, it is applied to a struct/union
183 * member or a func argument, and component_idx indicates which member
184 * or argument (0 ... vlen-1).
185 */
186 struct btf_decl_tag {
187 __s32 component_idx;
188 };
189
190 /* BTF_KIND_ENUM64 is followed by multiple "struct btf_enum64".
191 * The exact number of btf_enum64 is stored in the vlen (of the
192 * info in "struct btf_type").
193 */
194 struct btf_enum64 {
195 __u32 name_off;
196 __u32 val_lo32;
197 __u32 val_hi32;
198 };
199
200 #endif /* _UAPI__LINUX_BTF_H__ */
201
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