1//===- llvm/MC/MCELFObjectWriter.h - ELF Object Writer ----------*- 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#ifndef LLVM_MC_MCELFOBJECTWRITER_H
10#define LLVM_MC_MCELFOBJECTWRITER_H
11
12#include "llvm/BinaryFormat/ELF.h"
13#include "llvm/MC/MCObjectWriter.h"
14#include "llvm/MC/MCSectionELF.h"
15#include "llvm/Support/Casting.h"
16#include "llvm/Support/raw_ostream.h"
17#include "llvm/TargetParser/Triple.h"
18#include <cstdint>
19#include <vector>
20
21namespace llvm {
22
23class MCAssembler;
24class MCContext;
25class MCFixup;
26class MCSymbol;
27class MCSymbolELF;
28class MCValue;
29
30struct ELFRelocationEntry {
31 uint64_t Offset; // Where is the relocation.
32 const MCSymbolELF *Symbol; // The symbol to relocate with.
33 unsigned Type; // The type of the relocation.
34 uint64_t Addend; // The addend to use.
35 const MCSymbolELF *OriginalSymbol; // The original value of Symbol if we changed it.
36 uint64_t OriginalAddend; // The original value of addend.
37
38 ELFRelocationEntry(uint64_t Offset, const MCSymbolELF *Symbol, unsigned Type,
39 uint64_t Addend, const MCSymbolELF *OriginalSymbol,
40 uint64_t OriginalAddend)
41 : Offset(Offset), Symbol(Symbol), Type(Type), Addend(Addend),
42 OriginalSymbol(OriginalSymbol), OriginalAddend(OriginalAddend) {}
43
44 void print(raw_ostream &Out) const {
45 Out << "Off=" << Offset << ", Sym=" << Symbol << ", Type=" << Type
46 << ", Addend=" << Addend << ", OriginalSymbol=" << OriginalSymbol
47 << ", OriginalAddend=" << OriginalAddend;
48 }
49
50 LLVM_DUMP_METHOD void dump() const { print(Out&: errs()); }
51};
52
53class MCELFObjectTargetWriter : public MCObjectTargetWriter {
54 const uint8_t OSABI;
55 const uint8_t ABIVersion;
56 const uint16_t EMachine;
57 const unsigned HasRelocationAddend : 1;
58 const unsigned Is64Bit : 1;
59
60protected:
61 MCELFObjectTargetWriter(bool Is64Bit_, uint8_t OSABI_, uint16_t EMachine_,
62 bool HasRelocationAddend_, uint8_t ABIVersion_ = 0);
63
64public:
65 virtual ~MCELFObjectTargetWriter() = default;
66
67 Triple::ObjectFormatType getFormat() const override { return Triple::ELF; }
68 static bool classof(const MCObjectTargetWriter *W) {
69 return W->getFormat() == Triple::ELF;
70 }
71
72 static uint8_t getOSABI(Triple::OSType OSType) {
73 switch (OSType) {
74 case Triple::HermitCore:
75 return ELF::ELFOSABI_STANDALONE;
76 case Triple::PS4:
77 case Triple::FreeBSD:
78 return ELF::ELFOSABI_FREEBSD;
79 case Triple::Solaris:
80 return ELF::ELFOSABI_SOLARIS;
81 default:
82 return ELF::ELFOSABI_NONE;
83 }
84 }
85
86 virtual unsigned getRelocType(MCContext &Ctx, const MCValue &Target,
87 const MCFixup &Fixup, bool IsPCRel) const = 0;
88
89 virtual bool needsRelocateWithSymbol(const MCValue &Val, const MCSymbol &Sym,
90 unsigned Type) const;
91
92 virtual void sortRelocs(const MCAssembler &Asm,
93 std::vector<ELFRelocationEntry> &Relocs);
94
95 virtual void addTargetSectionFlags(MCContext &Ctx, MCSectionELF &Sec);
96
97 /// \name Accessors
98 /// @{
99 uint8_t getOSABI() const { return OSABI; }
100 uint8_t getABIVersion() const { return ABIVersion; }
101 uint16_t getEMachine() const { return EMachine; }
102 bool hasRelocationAddend() const { return HasRelocationAddend; }
103 bool is64Bit() const { return Is64Bit; }
104 /// @}
105
106 // Instead of changing everyone's API we pack the N64 Type fields
107 // into the existing 32 bit data unsigned.
108#define R_TYPE_SHIFT 0
109#define R_TYPE_MASK 0xffffff00
110#define R_TYPE2_SHIFT 8
111#define R_TYPE2_MASK 0xffff00ff
112#define R_TYPE3_SHIFT 16
113#define R_TYPE3_MASK 0xff00ffff
114#define R_SSYM_SHIFT 24
115#define R_SSYM_MASK 0x00ffffff
116
117 // N64 relocation type accessors
118 uint8_t getRType(uint32_t Type) const {
119 return (unsigned)((Type >> R_TYPE_SHIFT) & 0xff);
120 }
121 uint8_t getRType2(uint32_t Type) const {
122 return (unsigned)((Type >> R_TYPE2_SHIFT) & 0xff);
123 }
124 uint8_t getRType3(uint32_t Type) const {
125 return (unsigned)((Type >> R_TYPE3_SHIFT) & 0xff);
126 }
127 uint8_t getRSsym(uint32_t Type) const {
128 return (unsigned)((Type >> R_SSYM_SHIFT) & 0xff);
129 }
130
131 // N64 relocation type setting
132 static unsigned setRTypes(unsigned Value1, unsigned Value2, unsigned Value3) {
133 return ((Value1 & 0xff) << R_TYPE_SHIFT) |
134 ((Value2 & 0xff) << R_TYPE2_SHIFT) |
135 ((Value3 & 0xff) << R_TYPE3_SHIFT);
136 }
137 unsigned setRSsym(unsigned Value, unsigned Type) const {
138 return (Type & R_SSYM_MASK) | ((Value & 0xff) << R_SSYM_SHIFT);
139 }
140
141 // On AArch64, return a new section to be added to the ELF object that
142 // contains relocations used to describe every symbol that should have memory
143 // tags applied. Returns nullptr if no such section is necessary (i.e. there's
144 // no tagged globals).
145 virtual MCSectionELF *getMemtagRelocsSection(MCContext &Ctx) const {
146 return nullptr;
147 }
148};
149
150/// Construct a new ELF writer instance.
151///
152/// \param MOTW - The target specific ELF writer subclass.
153/// \param OS - The stream to write to.
154/// \returns The constructed object writer.
155std::unique_ptr<MCObjectWriter>
156createELFObjectWriter(std::unique_ptr<MCELFObjectTargetWriter> MOTW,
157 raw_pwrite_stream &OS, bool IsLittleEndian);
158
159std::unique_ptr<MCObjectWriter>
160createELFDwoObjectWriter(std::unique_ptr<MCELFObjectTargetWriter> MOTW,
161 raw_pwrite_stream &OS, raw_pwrite_stream &DwoOS,
162 bool IsLittleEndian);
163
164} // end namespace llvm
165
166#endif // LLVM_MC_MCELFOBJECTWRITER_H
167

source code of llvm/include/llvm/MC/MCELFObjectWriter.h