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 24-27: kind (e.g. int, ptr, array...etc)
37 * bits 28-30: 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 and VAR.
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) & 0x0f)
56 #define BTF_INFO_VLEN(info) ((info) & 0xffff)
57 #define BTF_INFO_KFLAG(info) ((info) >> 31)
58
59 #define BTF_KIND_UNKN 0 /* Unknown */
60 #define BTF_KIND_INT 1 /* Integer */
61 #define BTF_KIND_PTR 2 /* Pointer */
62 #define BTF_KIND_ARRAY 3 /* Array */
63 #define BTF_KIND_STRUCT 4 /* Struct */
64 #define BTF_KIND_UNION 5 /* Union */
65 #define BTF_KIND_ENUM 6 /* Enumeration */
66 #define BTF_KIND_FWD 7 /* Forward */
67 #define BTF_KIND_TYPEDEF 8 /* Typedef */
68 #define BTF_KIND_VOLATILE 9 /* Volatile */
69 #define BTF_KIND_CONST 10 /* Const */
70 #define BTF_KIND_RESTRICT 11 /* Restrict */
71 #define BTF_KIND_FUNC 12 /* Function */
72 #define BTF_KIND_FUNC_PROTO 13 /* Function Proto */
73 #define BTF_KIND_VAR 14 /* Variable */
74 #define BTF_KIND_DATASEC 15 /* Section */
75 #define BTF_KIND_MAX BTF_KIND_DATASEC
76 #define NR_BTF_KINDS (BTF_KIND_MAX + 1)
77
78 /* For some specific BTF_KIND, "struct btf_type" is immediately
79 * followed by extra data.
80 */
81
82 /* BTF_KIND_INT is followed by a u32 and the following
83 * is the 32 bits arrangement:
84 */
85 #define BTF_INT_ENCODING(VAL) (((VAL) & 0x0f000000) >> 24)
86 #define BTF_INT_OFFSET(VAL) (((VAL) & 0x00ff0000) >> 16)
87 #define BTF_INT_BITS(VAL) ((VAL) & 0x000000ff)
88
89 /* Attributes stored in the BTF_INT_ENCODING */
90 #define BTF_INT_SIGNED (1 << 0)
91 #define BTF_INT_CHAR (1 << 1)
92 #define BTF_INT_BOOL (1 << 2)
93
94 /* BTF_KIND_ENUM is followed by multiple "struct btf_enum".
95 * The exact number of btf_enum is stored in the vlen (of the
96 * info in "struct btf_type").
97 */
98 struct btf_enum {
99 __u32 name_off;
100 __s32 val;
101 };
102
103 /* BTF_KIND_ARRAY is followed by one "struct btf_array" */
104 struct btf_array {
105 __u32 type;
106 __u32 index_type;
107 __u32 nelems;
108 };
109
110 /* BTF_KIND_STRUCT and BTF_KIND_UNION are followed
111 * by multiple "struct btf_member". The exact number
112 * of btf_member is stored in the vlen (of the info in
113 * "struct btf_type").
114 */
115 struct btf_member {
116 __u32 name_off;
117 __u32 type;
118 /* If the type info kind_flag is set, the btf_member offset
119 * contains both member bitfield size and bit offset. The
120 * bitfield size is set for bitfield members. If the type
121 * info kind_flag is not set, the offset contains only bit
122 * offset.
123 */
124 __u32 offset;
125 };
126
127 /* If the struct/union type info kind_flag is set, the
128 * following two macros are used to access bitfield_size
129 * and bit_offset from btf_member.offset.
130 */
131 #define BTF_MEMBER_BITFIELD_SIZE(val) ((val) >> 24)
132 #define BTF_MEMBER_BIT_OFFSET(val) ((val) & 0xffffff)
133
134 /* BTF_KIND_FUNC_PROTO is followed by multiple "struct btf_param".
135 * The exact number of btf_param is stored in the vlen (of the
136 * info in "struct btf_type").
137 */
138 struct btf_param {
139 __u32 name_off;
140 __u32 type;
141 };
142
143 enum {
144 BTF_VAR_STATIC = 0,
145 BTF_VAR_GLOBAL_ALLOCATED,
146 };
147
148 /* BTF_KIND_VAR is followed by a single "struct btf_var" to describe
149 * additional information related to the variable such as its linkage.
150 */
151 struct btf_var {
152 __u32 linkage;
153 };
154
155 /* BTF_KIND_DATASEC is followed by multiple "struct btf_var_secinfo"
156 * to describe all BTF_KIND_VAR types it contains along with it's
157 * in-section offset as well as size.
158 */
159 struct btf_var_secinfo {
160 __u32 type;
161 __u32 offset;
162 __u32 size;
163 };
164
165 #endif /* _UAPI__LINUX_BTF_H__ */