LLVM  10.0.0svn
BTF.h
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1 //===-- BTF.h --------------------------------------------------*- C++ -*-===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 ///
9 /// \file
10 /// This file contains the layout of .BTF and .BTF.ext ELF sections.
11 ///
12 /// The binary layout for .BTF section:
13 /// struct Header
14 /// Type and Str subsections
15 /// The Type subsection is a collection of types with type id starting with 1.
16 /// The Str subsection is simply a collection of strings.
17 ///
18 /// The binary layout for .BTF.ext section:
19 /// struct ExtHeader
20 /// FuncInfo, LineInfo, FieldReloc and ExternReloc subsections
21 /// The FuncInfo subsection is defined as below:
22 /// BTFFuncInfo Size
23 /// struct SecFuncInfo for ELF section #1
24 /// A number of struct BPFFuncInfo for ELF section #1
25 /// struct SecFuncInfo for ELF section #2
26 /// A number of struct BPFFuncInfo for ELF section #2
27 /// ...
28 /// The LineInfo subsection is defined as below:
29 /// BPFLineInfo Size
30 /// struct SecLineInfo for ELF section #1
31 /// A number of struct BPFLineInfo for ELF section #1
32 /// struct SecLineInfo for ELF section #2
33 /// A number of struct BPFLineInfo for ELF section #2
34 /// ...
35 /// The FieldReloc subsection is defined as below:
36 /// BPFFieldReloc Size
37 /// struct SecFieldReloc for ELF section #1
38 /// A number of struct BPFFieldReloc for ELF section #1
39 /// struct SecFieldReloc for ELF section #2
40 /// A number of struct BPFFieldReloc for ELF section #2
41 /// ...
42 ///
43 /// The section formats are also defined at
44 /// https://github.com/torvalds/linux/blob/master/include/uapi/linux/btf.h
45 ///
46 //===----------------------------------------------------------------------===//
47 
48 #ifndef LLVM_LIB_TARGET_BPF_BTF_H
49 #define LLVM_LIB_TARGET_BPF_BTF_H
50 
51 namespace llvm {
52 namespace BTF {
53 
54 enum : uint32_t { MAGIC = 0xeB9F, VERSION = 1 };
55 
56 /// Sizes in bytes of various things in the BTF format.
57 enum {
58  HeaderSize = 24,
72 };
73 
74 /// The .BTF section header definition.
75 struct Header {
76  uint16_t Magic; ///< Magic value
77  uint8_t Version; ///< Version number
78  uint8_t Flags; ///< Extra flags
79  uint32_t HdrLen; ///< Length of this header
80 
81  /// All offsets are in bytes relative to the end of this header.
82  uint32_t TypeOff; ///< Offset of type section
83  uint32_t TypeLen; ///< Length of type section
84  uint32_t StrOff; ///< Offset of string section
85  uint32_t StrLen; ///< Length of string section
86 };
87 
88 enum : uint32_t {
89  MAX_VLEN = 0xffff ///< Max # of struct/union/enum members or func args
90 };
91 
92 enum TypeKinds : uint8_t {
93 #define HANDLE_BTF_KIND(ID, NAME) BTF_KIND_##NAME = ID,
94 #include "BTF.def"
95 };
96 
97 /// The BTF common type definition. Different kinds may have
98 /// additional information after this structure data.
99 struct CommonType {
100  /// Type name offset in the string table.
102 
103  /// "Info" bits arrangement:
104  /// Bits 0-15: vlen (e.g. # of struct's members)
105  /// Bits 16-23: unused
106  /// Bits 24-27: kind (e.g. int, ptr, array...etc)
107  /// Bits 28-30: unused
108  /// Bit 31: kind_flag, currently used by
109  /// struct, union and fwd
111 
112  /// "Size" is used by INT, ENUM, STRUCT and UNION.
113  /// "Size" tells the size of the type it is describing.
114  ///
115  /// "Type" is used by PTR, TYPEDEF, VOLATILE, CONST, RESTRICT,
116  /// FUNC, FUNC_PROTO and VAR.
117  /// "Type" is a type_id referring to another type.
118  union {
121  };
122 };
123 
124 // For some specific BTF_KIND, "struct CommonType" is immediately
125 // followed by extra data.
126 
127 // BTF_KIND_INT is followed by a u32 and the following
128 // is the 32 bits arrangement:
129 // BTF_INT_ENCODING(VAL) : (((VAL) & 0x0f000000) >> 24)
130 // BTF_INT_OFFSET(VAL) : (((VAL & 0x00ff0000)) >> 16)
131 // BTF_INT_BITS(VAL) : ((VAL) & 0x000000ff)
132 
133 /// Attributes stored in the INT_ENCODING.
134 enum : uint8_t {
135  INT_SIGNED = (1 << 0),
136  INT_CHAR = (1 << 1),
137  INT_BOOL = (1 << 2)
138 };
139 
140 /// BTF_KIND_ENUM is followed by multiple "struct BTFEnum".
141 /// The exact number of btf_enum is stored in the vlen (of the
142 /// info in "struct CommonType").
143 struct BTFEnum {
144  uint32_t NameOff; ///< Enum name offset in the string table
145  int32_t Val; ///< Enum member value
146 };
147 
148 /// BTF_KIND_ARRAY is followed by one "struct BTFArray".
149 struct BTFArray {
150  uint32_t ElemType; ///< Element type
151  uint32_t IndexType; ///< Index type
152  uint32_t Nelems; ///< Number of elements for this array
153 };
154 
155 /// BTF_KIND_STRUCT and BTF_KIND_UNION are followed
156 /// by multiple "struct BTFMember". The exact number
157 /// of BTFMember is stored in the vlen (of the info in
158 /// "struct CommonType").
159 ///
160 /// If the struct/union contains any bitfield member,
161 /// the Offset below represents BitOffset (bits 0 - 23)
162 /// and BitFieldSize(bits 24 - 31) with BitFieldSize = 0
163 /// for non bitfield members. Otherwise, the Offset
164 /// represents the BitOffset.
165 struct BTFMember {
166  uint32_t NameOff; ///< Member name offset in the string table
167  uint32_t Type; ///< Member type
168  uint32_t Offset; ///< BitOffset or BitFieldSize+BitOffset
169 };
170 
171 /// BTF_KIND_FUNC_PROTO are followed by multiple "struct BTFParam".
172 /// The exist number of BTFParam is stored in the vlen (of the info
173 /// in "struct CommonType").
174 struct BTFParam {
177 };
178 
179 /// Variable scoping information.
180 enum : uint8_t {
181  VAR_STATIC = 0, ///< Linkage: InternalLinkage
182  VAR_GLOBAL_ALLOCATED = 1, ///< Linkage: ExternalLinkage
183  VAR_GLOBAL_TENTATIVE = 2, ///< Linkage: CommonLinkage
184  VAR_GLOBAL_EXTERNAL = 3, ///< Linkage: ExternalLinkage
185 };
186 
187 /// BTF_KIND_DATASEC are followed by multiple "struct BTFDataSecVar".
188 /// The exist number of BTFDataSec is stored in the vlen (of the info
189 /// in "struct CommonType").
190 struct BTFDataSec {
191  uint32_t Type; ///< A BTF_KIND_VAR type
192  uint32_t Offset; ///< In-section offset
193  uint32_t Size; ///< Occupied memory size
194 };
195 
196 /// The .BTF.ext section header definition.
197 struct ExtHeader {
198  uint16_t Magic;
199  uint8_t Version;
200  uint8_t Flags;
202 
203  uint32_t FuncInfoOff; ///< Offset of func info section
204  uint32_t FuncInfoLen; ///< Length of func info section
205  uint32_t LineInfoOff; ///< Offset of line info section
206  uint32_t LineInfoLen; ///< Length of line info section
207  uint32_t FieldRelocOff; ///< Offset of offset reloc section
208  uint32_t FieldRelocLen; ///< Length of offset reloc section
209 };
210 
211 /// Specifying one function info.
212 struct BPFFuncInfo {
213  uint32_t InsnOffset; ///< Byte offset in the section
214  uint32_t TypeId; ///< Type id referring to .BTF type section
215 };
216 
217 /// Specifying function info's in one section.
218 struct SecFuncInfo {
219  uint32_t SecNameOff; ///< Section name index in the .BTF string table
220  uint32_t NumFuncInfo; ///< Number of func info's in this section
221 };
222 
223 /// Specifying one line info.
224 struct BPFLineInfo {
225  uint32_t InsnOffset; ///< Byte offset in this section
226  uint32_t FileNameOff; ///< File name index in the .BTF string table
227  uint32_t LineOff; ///< Line index in the .BTF string table
228  uint32_t LineCol; ///< Line num: line_col >> 10,
229  /// col num: line_col & 0x3ff
230 };
231 
232 /// Specifying line info's in one section.
233 struct SecLineInfo {
234  uint32_t SecNameOff; ///< Section name index in the .BTF string table
235  uint32_t NumLineInfo; ///< Number of line info's in this section
236 };
237 
238 /// Specifying one offset relocation.
240  uint32_t InsnOffset; ///< Byte offset in this section
241  uint32_t TypeID; ///< TypeID for the relocation
242  uint32_t OffsetNameOff; ///< The string to traverse types
243  uint32_t RelocKind; ///< What to patch the instruction
244 };
245 
246 /// Specifying offset relocation's in one section.
248  uint32_t SecNameOff; ///< Section name index in the .BTF string table
249  uint32_t NumFieldReloc; ///< Number of offset reloc's in this section
250 };
251 
252 } // End namespace BTF.
253 } // End namespace llvm.
254 
255 #endif
uint32_t HdrLen
Length of this header.
Definition: BTF.h:79
uint32_t Type
Definition: BTF.h:176
Max # of struct/union/enum members or func args.
Definition: BTF.h:89
uint32_t NumFuncInfo
Number of func info&#39;s in this section.
Definition: BTF.h:220
This class represents lattice values for constants.
Definition: AllocatorList.h:23
uint32_t HdrLen
Definition: BTF.h:201
uint32_t NameOff
Definition: BTF.h:175
uint32_t SecNameOff
Section name index in the .BTF string table.
Definition: BTF.h:219
Specifying one line info.
Definition: BTF.h:224
Specifying offset relocation&#39;s in one section.
Definition: BTF.h:247
uint32_t TypeID
TypeID for the relocation.
Definition: BTF.h:241
uint32_t Size
Definition: BTF.h:119
The BTF common type definition.
Definition: BTF.h:99
uint32_t InsnOffset
Byte offset in the section.
Definition: BTF.h:213
Specifying line info&#39;s in one section.
Definition: BTF.h:233
uint32_t Offset
BitOffset or BitFieldSize+BitOffset.
Definition: BTF.h:168
uint32_t Type
Member type.
Definition: BTF.h:167
uint32_t ElemType
Element type.
Definition: BTF.h:150
The .BTF.ext section header definition.
Definition: BTF.h:197
BTF_KIND_ENUM is followed by multiple "struct BTFEnum".
Definition: BTF.h:143
TypeKinds
Definition: BTF.h:92
uint8_t Version
Definition: BTF.h:199
uint32_t Offset
In-section offset.
Definition: BTF.h:192
uint32_t Type
Definition: BTF.h:120
uint32_t OffsetNameOff
The string to traverse types.
Definition: BTF.h:242
Specifying one offset relocation.
Definition: BTF.h:239
uint32_t FileNameOff
File name index in the .BTF string table.
Definition: BTF.h:226
uint32_t TypeLen
Length of type section.
Definition: BTF.h:83
uint8_t Flags
Definition: BTF.h:200
BTF_KIND_FUNC_PROTO are followed by multiple "struct BTFParam".
Definition: BTF.h:174
Specifying function info&#39;s in one section.
Definition: BTF.h:218
uint32_t LineCol
Line num: line_col >> 10, col num: line_col & 0x3ff.
Definition: BTF.h:228
BTF_KIND_DATASEC are followed by multiple "struct BTFDataSecVar".
Definition: BTF.h:190
Linkage: InternalLinkage.
Definition: BTF.h:181
uint8_t Flags
Extra flags.
Definition: BTF.h:78
uint32_t FuncInfoOff
Offset of func info section.
Definition: BTF.h:203
uint32_t SecNameOff
Section name index in the .BTF string table.
Definition: BTF.h:234
uint16_t Magic
Magic value.
Definition: BTF.h:76
uint32_t NameOff
Member name offset in the string table.
Definition: BTF.h:166
Specifying one function info.
Definition: BTF.h:212
uint32_t FieldRelocLen
Length of offset reloc section.
Definition: BTF.h:208
uint32_t TypeId
Type id referring to .BTF type section.
Definition: BTF.h:214
BTF_KIND_STRUCT and BTF_KIND_UNION are followed by multiple "struct BTFMember".
Definition: BTF.h:165
uint32_t NumFieldReloc
Number of offset reloc&#39;s in this section.
Definition: BTF.h:249
uint32_t NameOff
Type name offset in the string table.
Definition: BTF.h:101
uint32_t Size
Occupied memory size.
Definition: BTF.h:193
uint32_t FieldRelocOff
Offset of offset reloc section.
Definition: BTF.h:207
uint32_t InsnOffset
Byte offset in this section.
Definition: BTF.h:225
uint16_t Magic
Definition: BTF.h:198
int32_t Val
Enum member value.
Definition: BTF.h:145
uint32_t NameOff
Enum name offset in the string table.
Definition: BTF.h:144
uint32_t InsnOffset
Byte offset in this section.
Definition: BTF.h:240
uint32_t Type
A BTF_KIND_VAR type.
Definition: BTF.h:191
uint32_t FuncInfoLen
Length of func info section.
Definition: BTF.h:204
uint32_t IndexType
Index type.
Definition: BTF.h:151
uint32_t RelocKind
What to patch the instruction.
Definition: BTF.h:243
BTF_KIND_ARRAY is followed by one "struct BTFArray".
Definition: BTF.h:149
Linkage: CommonLinkage.
Definition: BTF.h:183
uint32_t LineInfoLen
Length of line info section.
Definition: BTF.h:206
Linkage: ExternalLinkage.
Definition: BTF.h:184
uint32_t Nelems
Number of elements for this array.
Definition: BTF.h:152
uint32_t StrOff
Offset of string section.
Definition: BTF.h:84
Linkage: ExternalLinkage.
Definition: BTF.h:182
uint32_t StrLen
Length of string section.
Definition: BTF.h:85
uint32_t SecNameOff
Section name index in the .BTF string table.
Definition: BTF.h:248
uint32_t LineOff
Line index in the .BTF string table.
Definition: BTF.h:227
uint32_t TypeOff
All offsets are in bytes relative to the end of this header.
Definition: BTF.h:82
uint8_t Version
Version number.
Definition: BTF.h:77
The .BTF section header definition.
Definition: BTF.h:75
uint32_t Info
"Info" bits arrangement: Bits 0-15: vlen (e.g.
Definition: BTF.h:110
uint32_t NumLineInfo
Number of line info&#39;s in this section.
Definition: BTF.h:235
uint32_t LineInfoOff
Offset of line info section.
Definition: BTF.h:205