squiid/llvm
1
0
Fork 0
Code Issues Pull requests Activity

[JITLink] Add initial Aarch64 support

Browse source 
Set up basic infrastructure for 64-bit ARM architecture support in JITLink. It allows for loading a minimal object file and resolving a single relocation. Advanced features like GOT and PLT handling or relaxations were intentionally left out for the moment.

This patch follows the idea to keep implementations for ARM (32-bit) and Aaarch64 (64-bit) separate, because:
* it might be easier to share code with the MachO "arm64" JITLink backend
* LLVM has individual targets for ARM and Aaarch64 as well

Reviewed By: lhames

Differential Revision: https://reviews.llvm.org/D108986
This commit is contained in:
Stefan Gränitz 2021-09-03 10:46:40 +02:00
parent 562521e2d1
commit 2ed91da0f1
7 changed files with 371 additions and 2 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

39
llvm/include/llvm/ExecutionEngine/JITLink/ELF_aarch64.h Normal file
View file

@ -0,0 +1,39 @@
//===--- ELF_aarch64.h - JIT link functions for ELF/aarch64 --*- C++ -*----===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
//===----------------------------------------------------------------------===//
//
// jit-link functions for ELF/aarch64.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_EXECUTIONENGINE_JITLINK_ELF_AARCH64_H
#define LLVM_EXECUTIONENGINE_JITLINK_ELF_AARCH64_H
#include "llvm/ExecutionEngine/JITLink/JITLink.h"
namespace llvm {
namespace jitlink {
/// Create a LinkGraph from an ELF/aarch64 relocatable object
///
/// Note: The graph does not take ownership of the underlying buffer, nor copy
/// its contents. The caller is responsible for ensuring that the object buffer
/// outlives the graph.
Expected<std::unique_ptr<LinkGraph>>
createLinkGraphFromELFObject_aarch64(MemoryBufferRef ObjectBuffer);
/// jit-link the given object buffer, which must be a ELF aarch64 relocatable
/// object file.
void link_ELF_aarch64(std::unique_ptr<LinkGraph> G,
std::unique_ptr<JITLinkContext> Ctx);
} // end namespace jitlink
} // end namespace llvm
#endif // LLVM_EXECUTIONENGINE_JITLINK_ELF_AARCH64_H

38
llvm/include/llvm/ExecutionEngine/JITLink/aarch64.h Normal file
View file

@ -0,0 +1,38 @@
//=== aarch64.h - Generic JITLink aarch64 edge kinds, utilities -*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// Generic utilities for graphs representing aarch64 objects.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_EXECUTIONENGINE_JITLINK_AARCH64_H
#define LLVM_EXECUTIONENGINE_JITLINK_AARCH64_H
#include "llvm/ExecutionEngine/JITLink/JITLink.h"
namespace llvm {
namespace jitlink {
namespace aarch64 {
/// Represets aarch64 fixups
enum EdgeKind_aarch64 : Edge::Kind {
/// Set a CALL immediate field to bits [27:2] of X = Target - Fixup + Addend
R_AARCH64_CALL26 = Edge::FirstRelocation,
};
/// Returns a string name for the given aarch64 edge. For debugging purposes
/// only
const char *getEdgeKindName(Edge::Kind K);
} // namespace aarch64
} // namespace jitlink
} // namespace llvm
#endif // LLVM_EXECUTIONENGINE_JITLINK_AARCH64_H

5
llvm/lib/ExecutionEngine/JITLink/CMakeLists.txt
View file

@ -13,13 +13,14 @@ add_llvm_component_library(LLVMJITLink
MachOLinkGraphBuilder.cpp
# ELF
ELF.cpp
ELFLinkGraphBuilder.cpp
ELF_aarch64.cpp
ELF_riscv.cpp
ELF_x86_64.cpp
# Architectures:
aarch64.cpp
riscv.cpp
x86_64.cpp
@ -35,7 +36,7 @@ add_llvm_component_library(LLVMJITLink
OrcTargetProcess
Support
)
target_link_libraries(LLVMJITLink
PRIVATE
LLVMObject

6
llvm/lib/ExecutionEngine/JITLink/ELF.cpp
View file

@ -13,6 +13,7 @@
#include "llvm/ExecutionEngine/JITLink/ELF.h"
#include "llvm/BinaryFormat/ELF.h"
#include "llvm/ExecutionEngine/JITLink/ELF_aarch64.h"
#include "llvm/ExecutionEngine/JITLink/ELF_riscv.h"
#include "llvm/ExecutionEngine/JITLink/ELF_x86_64.h"
#include "llvm/Object/ELF.h"
@ -64,6 +65,8 @@ createLinkGraphFromELFObject(MemoryBufferRef ObjectBuffer) {
return TargetMachineArch.takeError();
switch (*TargetMachineArch) {
case ELF::EM_AARCH64:
return createLinkGraphFromELFObject_aarch64(ObjectBuffer);
case ELF::EM_RISCV:
return createLinkGraphFromELFObject_riscv(ObjectBuffer);
case ELF::EM_X86_64:
@ -78,6 +81,9 @@ createLinkGraphFromELFObject(MemoryBufferRef ObjectBuffer) {
void link_ELF(std::unique_ptr<LinkGraph> G,
std::unique_ptr<JITLinkContext> Ctx) {
switch (G->getTargetTriple().getArch()) {
case Triple::aarch64:
link_ELF_aarch64(std::move(G), std::move(Ctx));
return;
case Triple::riscv32:
case Triple::riscv64:
link_ELF_riscv(std::move(G), std::move(Ctx));

220
llvm/lib/ExecutionEngine/JITLink/ELF_aarch64.cpp Normal file
View file

@ -0,0 +1,220 @@
//===----- ELF_aarch64.cpp - JIT linker implementation for ELF/aarch64 ----===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// ELF/aarch64 jit-link implementation.
//
//===----------------------------------------------------------------------===//
#include "llvm/ExecutionEngine/JITLink/ELF_aarch64.h"
#include "ELFLinkGraphBuilder.h"
#include "JITLinkGeneric.h"
#include "llvm/BinaryFormat/ELF.h"
#include "llvm/ExecutionEngine/JITLink/aarch64.h"
#include "llvm/Object/ELFObjectFile.h"
#define DEBUG_TYPE "jitlink"
using namespace llvm;
using namespace llvm::jitlink;
namespace llvm {
namespace jitlink {
class ELFJITLinker_aarch64 : public JITLinker<ELFJITLinker_aarch64> {
friend class JITLinker<ELFJITLinker_aarch64>;
public:
ELFJITLinker_aarch64(std::unique_ptr<JITLinkContext> Ctx,
std::unique_ptr<LinkGraph> G,
PassConfiguration PassConfig)
: JITLinker(std::move(Ctx), std::move(G), std::move(PassConfig)) {}
private:
Error applyFixup(LinkGraph &G, Block &B, const Edge &E) const {
using namespace aarch64;
using namespace llvm::support;
char *BlockWorkingMem = B.getAlreadyMutableContent().data();
char *FixupPtr = BlockWorkingMem + E.getOffset();
JITTargetAddress FixupAddress = B.getAddress() + E.getOffset();
switch (E.getKind()) {
case aarch64::R_AARCH64_CALL26: {
assert((FixupAddress & 0x3) == 0 && "Call-inst is not 32-bit aligned");
int64_t Value = E.getTarget().getAddress() - FixupAddress + E.getAddend();
if (static_cast<uint64_t>(Value) & 0x3)
return make_error<JITLinkError>("Call target is not 32-bit aligned");
if (!fitsRangeSignedInt<27>(Value))
return makeTargetOutOfRangeError(G, B, E);
uint32_t RawInstr = *(little32_t *)FixupPtr;
assert((RawInstr & 0x7fffffff) == 0x14000000 &&
"RawInstr isn't a B or BR immediate instruction");
uint32_t Imm = (static_cast<uint32_t>(Value) & ((1 << 28) - 1)) >> 2;
uint32_t FixedInstr = RawInstr | Imm;
*(little32_t *)FixupPtr = FixedInstr;
break;
}
}
return Error::success();
}
template <uint8_t Bits> static bool fitsRangeSignedInt(int64_t Value) {
return Value >= -(1 << Bits) && Value < (1 << Bits);
}
};
template <typename ELFT>
class ELFLinkGraphBuilder_aarch64 : public ELFLinkGraphBuilder<ELFT> {
private:
static Expected<aarch64::EdgeKind_aarch64>
getRelocationKind(const uint32_t Type) {
using namespace aarch64;
switch (Type) {
case ELF::R_AARCH64_CALL26:
return EdgeKind_aarch64::R_AARCH64_CALL26;
}
return make_error<JITLinkError>("Unsupported aarch64 relocation:" +
formatv("{0:d}", Type));
}
Error addRelocations() override {
using Base = ELFLinkGraphBuilder<ELFT>;
LLVM_DEBUG(dbgs() << "Adding relocations\n");
// Iterate sections and only process the interesting ones.
for (auto &SecRef : Base::Sections) {
if (SecRef.sh_type != ELF::SHT_RELA && SecRef.sh_type != ELF::SHT_REL)
continue;
auto RelSectName = Base::Obj.getSectionName(SecRef);
if (!RelSectName)
return RelSectName.takeError();
LLVM_DEBUG({
dbgs() << "Adding relocations from section " << *RelSectName << "\n";
});
auto UpdateSect = Base::Obj.getSection(SecRef.sh_info);
if (!UpdateSect)
return UpdateSect.takeError();
auto UpdateSectName = Base::Obj.getSectionName(**UpdateSect);
if (!UpdateSectName)
return UpdateSectName.takeError();
// Don't process relocations for debug sections.
if (Base::isDwarfSection(*UpdateSectName)) {
LLVM_DEBUG({
dbgs() << " Target is dwarf section " << *UpdateSectName
<< ". Skipping.\n";
});
continue;
}
LLVM_DEBUG(dbgs() << " For target section " << *UpdateSectName << "\n");
auto *JITSection = Base::G->findSectionByName(*UpdateSectName);
if (!JITSection)
return make_error<llvm::StringError>(
"Refencing a section that wasn't added to graph" + *UpdateSectName,
llvm::inconvertibleErrorCode());
auto Relocations = Base::Obj.relas(SecRef);
if (!Relocations)
return Relocations.takeError();
for (const auto &Rela : *Relocations) {
auto Type = Rela.getType(false);
LLVM_DEBUG({
dbgs() << "Relocation Type: " << Type << "\n"
<< "Name: " << Base::Obj.getRelocationTypeName(Type) << "\n";
});
auto SymbolIndex = Rela.getSymbol(false);
auto Symbol = Base::Obj.getRelocationSymbol(Rela, Base::SymTabSec);
if (!Symbol)
return Symbol.takeError();
auto BlockToFix = *(JITSection->blocks().begin());
auto *TargetSymbol = Base::getGraphSymbol(SymbolIndex);
if (!TargetSymbol) {
return make_error<llvm::StringError>(
"Could not find symbol at given index, did you add it to "
"JITSymbolTable? index: " +
std::to_string(SymbolIndex) + ", shndx: " +
std::to_string((*Symbol)->st_shndx) + " Size of table: " +
std::to_string(Base::GraphSymbols.size()),
llvm::inconvertibleErrorCode());
}
int64_t Addend = Rela.r_addend;
JITTargetAddress FixupAddress = (*UpdateSect)->sh_addr + Rela.r_offset;
LLVM_DEBUG({
dbgs() << "Processing relocation at "
<< format("0x%016" PRIx64, FixupAddress) << "\n";
});
auto Kind = getRelocationKind(Type);
if (!Kind)
return Kind.takeError();
BlockToFix->addEdge(*Kind, FixupAddress - BlockToFix->getAddress(),
*TargetSymbol, Addend);
}
}
return Error::success();
}
public:
ELFLinkGraphBuilder_aarch64(StringRef FileName,
const object::ELFFile<ELFT> &Obj, const Triple T)
: ELFLinkGraphBuilder<ELFT>(Obj, std::move(T), FileName,
aarch64::getEdgeKindName) {}
};
Expected<std::unique_ptr<LinkGraph>>
createLinkGraphFromELFObject_aarch64(MemoryBufferRef ObjectBuffer) {
LLVM_DEBUG({
dbgs() << "Building jitlink graph for new input "
<< ObjectBuffer.getBufferIdentifier() << "...\n";
});
auto ELFObj = object::ObjectFile::createELFObjectFile(ObjectBuffer);
if (!ELFObj)
return ELFObj.takeError();
assert((*ELFObj)->getArch() == Triple::aarch64 &&
"Only AArch64 (little endian) is supported for now");
auto &ELFObjFile = cast<object::ELFObjectFile<object::ELF64LE>>(**ELFObj);
return ELFLinkGraphBuilder_aarch64<object::ELF64LE>((*ELFObj)->getFileName(),
ELFObjFile.getELFFile(),
(*ELFObj)->makeTriple())
.buildGraph();
}
void link_ELF_aarch64(std::unique_ptr<LinkGraph> G,
std::unique_ptr<JITLinkContext> Ctx) {
PassConfiguration Config;
const Triple &TT = G->getTargetTriple();
if (Ctx->shouldAddDefaultTargetPasses(TT)) {
if (auto MarkLive = Ctx->getMarkLivePass(TT))
Config.PrePrunePasses.push_back(std::move(MarkLive));
else
Config.PrePrunePasses.push_back(markAllSymbolsLive);
}
if (auto Err = Ctx->modifyPassConfig(*G, Config))
return Ctx->notifyFailed(std::move(Err));
ELFJITLinker_aarch64::link(std::move(Ctx), std::move(G), std::move(Config));
}
} // namespace jitlink
} // namespace llvm

30
llvm/lib/ExecutionEngine/JITLink/aarch64.cpp Normal file
View file

@ -0,0 +1,30 @@
//===---- aarch64.cpp - Generic JITLink aarch64 edge kinds, utilities -----===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// Generic utilities for graphs representing aarch64 objects.
//
//===----------------------------------------------------------------------===//
#include "llvm/ExecutionEngine/JITLink/aarch64.h"
#define DEBUG_TYPE "jitlink"
namespace llvm {
namespace jitlink {
namespace aarch64 {
const char *getEdgeKindName(Edge::Kind K) {
switch (K) {
case R_AARCH64_CALL26:
return "R_AARCH64_CALL26";
}
return getGenericEdgeKindName(K);
}
} // namespace aarch64
} // namespace jitlink
} // namespace llvm

35
llvm/test/ExecutionEngine/JITLink/AArch64/ELF_aarch64_minimal.s Normal file
View file

@ -0,0 +1,35 @@
# RUN: rm -rf %t && mkdir -p %t
# RUN: llvm-mc -triple=aarch64-unknown-linux-gnu -relax-relocations=false -position-independent -filetype=obj -o %t/aarch64_reloc.o %s
# RUN: llvm-jitlink -noexec %t/aarch64_reloc.o
.text
.globl sub1
.p2align 2
.type sub1,@function
sub1:
sub sp, sp, #16
str w0, [sp, #12]
ldr w8, [sp, #12]
subs w0, w8, #1
add sp, sp, #16
ret
.size sub1, .-sub1
.globl main
.p2align 2
.type main,@function
main:
sub sp, sp, #32
stp x29, x30, [sp, #16]
add x29, sp, #16
stur wzr, [x29, #-4]
str w0, [sp, #8]
str x1, [sp]
ldr w0, [sp, #8]
bl sub1
ldp x29, x30, [sp, #16]
add sp, sp, #32
ret
.size main, .-main