LLVM
17.0.0git
lib
Target
BPF
MCTargetDesc
BPFELFObjectWriter.cpp
Go to the documentation of this file.
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//===-- BPFELFObjectWriter.cpp - BPF ELF Writer ---------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#include "
MCTargetDesc/BPFMCTargetDesc.h
"
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#include "
llvm/BinaryFormat/ELF.h
"
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#include "
llvm/MC/MCELFObjectWriter.h
"
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#include "
llvm/MC/MCFixup.h
"
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#include "
llvm/MC/MCObjectWriter.h
"
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#include "
llvm/MC/MCValue.h
"
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#include "
llvm/Support/ErrorHandling.h
"
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#include <cstdint>
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using namespace
llvm
;
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namespace
{
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class
BPFELFObjectWriter :
public
MCELFObjectTargetWriter
{
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public
:
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BPFELFObjectWriter(uint8_t OSABI);
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~BPFELFObjectWriter()
override
=
default
;
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protected
:
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unsigned
getRelocType(
MCContext
&Ctx,
const
MCValue
&
Target
,
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const
MCFixup
&Fixup,
bool
IsPCRel)
const override
;
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};
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}
// end anonymous namespace
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BPFELFObjectWriter::BPFELFObjectWriter(uint8_t OSABI)
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:
MCELFObjectTargetWriter
(
/*Is64Bit*/
true
, OSABI,
ELF
::
EM_BPF
,
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/*HasRelocationAddend*/
false
) {}
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unsigned
BPFELFObjectWriter::getRelocType(
MCContext
&Ctx,
const
MCValue
&
Target
,
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const
MCFixup
&
Fixup
,
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bool
IsPCRel)
const
{
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// determine the type of the relocation
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switch
(
Fixup
.getKind()) {
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default
:
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llvm_unreachable
(
"invalid fixup kind!"
);
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case
FK_SecRel_8
:
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// LD_imm64 instruction.
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return
ELF::R_BPF_64_64;
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case
FK_PCRel_4
:
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// CALL instruction.
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return
ELF::R_BPF_64_32;
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case
FK_Data_8
:
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return
ELF::R_BPF_64_ABS64;
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case
FK_Data_4
:
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if
(
const
MCSymbolRefExpr
*
A
=
Target
.getSymA()) {
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const
MCSymbol
&Sym =
A
->getSymbol();
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if
(Sym.
isDefined
()) {
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MCSection
&
Section
= Sym.
getSection
();
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const
MCSectionELF
*SectionELF = dyn_cast<MCSectionELF>(&
Section
);
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assert
(SectionELF &&
"Null section for reloc symbol"
);
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unsigned
Flags
= SectionELF->
getFlags
();
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if
(Sym.
isTemporary
()) {
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// .BTF.ext generates FK_Data_4 relocations for
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// insn offset by creating temporary labels.
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// The reloc symbol should be in text section.
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// Use a different relocation to instruct ExecutionEngine
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// RuntimeDyld not to do relocation for it, yet still to
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// allow lld to do proper adjustment when merging sections.
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if
((Flags &
ELF::SHF_ALLOC
) && (Flags &
ELF::SHF_EXECINSTR
))
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return
ELF::R_BPF_64_NODYLD32;
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}
else
{
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// .BTF generates FK_Data_4 relocations for variable
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// offset in DataSec kind.
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// The reloc symbol should be in data section.
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if
((Flags &
ELF::SHF_ALLOC
) && (Flags &
ELF::SHF_WRITE
))
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return
ELF::R_BPF_64_NODYLD32;
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}
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}
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}
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return
ELF::R_BPF_64_ABS32;
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}
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}
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std::unique_ptr<MCObjectTargetWriter>
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llvm::createBPFELFObjectWriter
(uint8_t OSABI) {
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return
std::make_unique<BPFELFObjectWriter>(OSABI);
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}
BPFMCTargetDesc.h
llvm::ELF::SHF_EXECINSTR
@ SHF_EXECINSTR
Definition:
ELF.h:1086
llvm
This is an optimization pass for GlobalISel generic memory operations.
Definition:
AddressRanges.h:18
llvm::MCSymbol
MCSymbol - Instances of this class represent a symbol name in the MC file, and MCSymbols are created ...
Definition:
MCSymbol.h:41
llvm::MCSymbol::isTemporary
bool isTemporary() const
isTemporary - Check if this is an assembler temporary symbol.
Definition:
MCSymbol.h:220
llvm::MCContext
Context object for machine code objects.
Definition:
MCContext.h:76
llvm::Target
Target - Wrapper for Target specific information.
Definition:
TargetRegistry.h:149
ErrorHandling.h
llvm::MCSymbol::isDefined
bool isDefined() const
isDefined - Check if this symbol is defined (i.e., it has an address).
Definition:
MCSymbol.h:248
llvm::ELF::SHF_ALLOC
@ SHF_ALLOC
Definition:
ELF.h:1083
llvm::createBPFELFObjectWriter
std::unique_ptr< MCObjectTargetWriter > createBPFELFObjectWriter(uint8_t OSABI)
Definition:
BPFELFObjectWriter.cpp:87
llvm::MCSectionELF
This represents a section on linux, lots of unix variants and some bare metal systems.
Definition:
MCSectionELF.h:26
llvm::ARMBuildAttrs::Section
@ Section
Legacy Tags.
Definition:
ARMBuildAttributes.h:82
llvm::FK_Data_4
@ FK_Data_4
A four-byte fixup.
Definition:
MCFixup.h:25
ELF.h
llvm::MCSymbol::getSection
MCSection & getSection() const
Get the section associated with a defined, non-absolute symbol.
Definition:
MCSymbol.h:267
false
Definition:
StackSlotColoring.cpp:141
llvm::MCELFObjectTargetWriter
Definition:
MCELFObjectWriter.h:53
MCELFObjectWriter.h
true
basic Basic Alias true
Definition:
BasicAliasAnalysis.cpp:1804
assert
assert(ImpDefSCC.getReg()==AMDGPU::SCC &&ImpDefSCC.isDef())
llvm::ELF::SHF_WRITE
@ SHF_WRITE
Definition:
ELF.h:1080
llvm::FK_PCRel_4
@ FK_PCRel_4
A four-byte pc relative fixup.
Definition:
MCFixup.h:30
llvm::MCSymbolRefExpr
Represent a reference to a symbol from inside an expression.
Definition:
MCExpr.h:192
llvm::ELF::EM_BPF
@ EM_BPF
Definition:
ELF.h:319
llvm::logicalview::LVBinaryType::ELF
@ ELF
llvm::MCSectionELF::getFlags
unsigned getFlags() const
Definition:
MCSectionELF.h:73
Fixup
PowerPC TLS Dynamic Call Fixup
Definition:
PPCTLSDynamicCall.cpp:215
llvm_unreachable
#define llvm_unreachable(msg)
Marks that the current location is not supposed to be reachable.
Definition:
ErrorHandling.h:143
A
* A
Definition:
README_ALTIVEC.txt:89
MCFixup.h
llvm::MCSection
Instances of this class represent a uniqued identifier for a section in the current translation unit.
Definition:
MCSection.h:39
MCObjectWriter.h
llvm::FK_SecRel_8
@ FK_SecRel_8
A eight-byte section relative fixup.
Definition:
MCFixup.h:43
MCValue.h
llvm::FK_Data_8
@ FK_Data_8
A eight-byte fixup.
Definition:
MCFixup.h:26
llvm::MCValue
This represents an "assembler immediate".
Definition:
MCValue.h:36
llvm::omp::RTLDependInfoFields::Flags
@ Flags
llvm::MCFixup
Encode information on a single operation to perform on a byte sequence (e.g., an encoded instruction)...
Definition:
MCFixup.h:71
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