1 //===-- BTF.h --------------------------------------------------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
11 /// This file contains the layout of .BTF and .BTF.ext ELF sections.
13 /// The binary layout for .BTF section:
15 /// Type and Str subsections
16 /// The Type subsection is a collection of types with type id starting with 1.
17 /// The Str subsection is simply a collection of strings.
19 /// The binary layout for .BTF.ext section:
21 /// FuncInfo and LineInfo subsections
22 /// The FuncInfo subsection is defined as below:
24 /// struct SecFuncInfo for ELF section #1
25 /// A number of struct BPFFuncInfo for ELF section #1
26 /// struct SecFuncInfo for ELF section #2
27 /// A number of struct BPFFuncInfo for ELF section #2
29 /// The LineInfo subsection is defined as below:
31 /// struct SecLineInfo for ELF section #1
32 /// A number of struct BPFLineInfo for ELF section #1
33 /// struct SecLineInfo for ELF section #2
34 /// A number of struct BPFLineInfo for ELF section #2
37 /// The section formats are also defined at
38 /// https://github.com/torvalds/linux/blob/master/include/uapi/linux/btf.h
40 //===----------------------------------------------------------------------===//
42 #ifndef LLVM_LIB_TARGET_BPF_BTF_H
43 #define LLVM_LIB_TARGET_BPF_BTF_H
48 enum : uint32_t { MAGIC = 0xeB9F, VERSION = 1 };
50 /// Sizes in bytes of various things in the BTF format.
65 /// The .BTF section header definition.
67 uint16_t Magic; ///< Magic value
68 uint8_t Version; ///< Version number
69 uint8_t Flags; ///< Extra flags
70 uint32_t HdrLen; ///< Length of this header
72 /// All offsets are in bytes relative to the end of this header.
73 uint32_t TypeOff; ///< Offset of type section
74 uint32_t TypeLen; ///< Length of type section
75 uint32_t StrOff; ///< Offset of string section
76 uint32_t StrLen; ///< Length of string section
80 MAX_VLEN = 0xffff ///< Max # of struct/union/enum members or func args
83 enum TypeKinds : uint8_t {
84 #define HANDLE_BTF_KIND(ID, NAME) BTF_KIND_##NAME = ID,
88 /// The BTF common type definition. Different kinds may have
89 /// additional information after this structure data.
91 /// Type name offset in the string table.
94 /// "Info" bits arrangement:
95 /// Bits 0-15: vlen (e.g. # of struct's members)
96 /// Bits 16-23: unused
97 /// Bits 24-27: kind (e.g. int, ptr, array...etc)
98 /// Bits 28-30: unused
99 /// Bit 31: kind_flag, currently used by
100 /// struct, union and fwd
103 /// "Size" is used by INT, ENUM, STRUCT and UNION.
104 /// "Size" tells the size of the type it is describing.
106 /// "Type" is used by PTR, TYPEDEF, VOLATILE, CONST, RESTRICT,
107 /// FUNC and FUNC_PROTO.
108 /// "Type" is a type_id referring to another type.
115 // For some specific BTF_KIND, "struct CommonType" is immediately
116 // followed by extra data.
118 // BTF_KIND_INT is followed by a u32 and the following
119 // is the 32 bits arrangement:
120 // BTF_INT_ENCODING(VAL) : (((VAL) & 0x0f000000) >> 24)
121 // BTF_INT_OFFSET(VAL) : (((VAL & 0x00ff0000)) >> 16)
122 // BTF_INT_BITS(VAL) : ((VAL) & 0x000000ff)
124 /// Attributes stored in the INT_ENCODING.
125 enum : uint8_t { INT_SIGNED = (1 << 0), INT_CHAR = (1 << 1), INT_BOOL = (1 << 2) };
127 /// BTF_KIND_ENUM is followed by multiple "struct BTFEnum".
128 /// The exact number of btf_enum is stored in the vlen (of the
129 /// info in "struct CommonType").
131 uint32_t NameOff; ///< Enum name offset in the string table
132 int32_t Val; ///< Enum member value
135 /// BTF_KIND_ARRAY is followed by one "struct BTFArray".
137 uint32_t ElemType; ///< Element type
138 uint32_t IndexType; ///< Index type
139 uint32_t Nelems; ///< Number of elements for this array
142 /// BTF_KIND_STRUCT and BTF_KIND_UNION are followed
143 /// by multiple "struct BTFMember". The exact number
144 /// of BTFMember is stored in the vlen (of the info in
145 /// "struct CommonType").
147 /// If the struct/union contains any bitfield member,
148 /// the Offset below represents BitOffset (bits 0 - 23)
149 /// and BitFieldSize(bits 24 - 31) with BitFieldSize = 0
150 /// for non bitfield members. Otherwise, the Offset
151 /// represents the BitOffset.
153 uint32_t NameOff; ///< Member name offset in the string table
154 uint32_t Type; ///< Member type
155 uint32_t Offset; ///< BitOffset or BitFieldSize+BitOffset
158 /// BTF_KIND_FUNC_PROTO are followed by multiple "struct BTFParam".
159 /// The exist number of BTFParam is stored in the vlen (of the info
160 /// in "struct CommonType").
166 /// The .BTF.ext section header definition.
173 uint32_t FuncInfoOff; ///< Offset of func info section
174 uint32_t FuncInfoLen; ///< Length of func info section
175 uint32_t LineInfoOff; ///< Offset of line info section
176 uint32_t LineInfoLen; ///< Length of line info section
179 /// Specifying one function info.
181 uint32_t InsnOffset; ///< Byte offset in the section
182 uint32_t TypeId; ///< Type id referring to .BTF type section
185 /// Specifying function info's in one section.
187 uint32_t SecNameOff; ///< Section name index in the .BTF string table
188 uint32_t NumFuncInfo; ///< Number of func info's in this section
191 /// Specifying one line info.
193 uint32_t InsnOffset; ///< Byte offset in this section
194 uint32_t FileNameOff; ///< File name index in the .BTF string table
195 uint32_t LineOff; ///< Line index in the .BTF string table
196 uint32_t LineCol; ///< Line num: line_col >> 10,
197 /// col num: line_col & 0x3ff
200 /// Specifying line info's in one section.
202 uint32_t SecNameOff; ///< Section name index in the .BTF string tble
203 uint32_t NumLineInfo; ///< Number of line info's in this section
206 } // End namespace BTF.
207 } // End namespace llvm.