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//===----- 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"
#include "llvm/Support/MathExtras.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();
auto FixupAddress = B.getAddress() + E.getOffset();
switch (E.getKind()) {
case aarch64::R_AARCH64_CALL26: {
assert((FixupAddress.getValue() & 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 (!isInt<28>(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 <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 {
LLVM_DEBUG(dbgs() << "Processing relocations:\n");
using Base = ELFLinkGraphBuilder<ELFT>;
using Self = ELFLinkGraphBuilder_aarch64<ELFT>;
for (const auto &RelSect : Base::Sections)
if (Error Err = Base::forEachRelocation(RelSect, this,
&Self::addSingleRelocation))
return Err;
return Error::success();
}
Error addSingleRelocation(const typename ELFT::Rela &Rel,
const typename ELFT::Shdr &FixupSect,
Block &BlockToFix) {
using Base = ELFLinkGraphBuilder<ELFT>;
uint32_t SymbolIndex = Rel.getSymbol(false);
auto ObjSymbol = Base::Obj.getRelocationSymbol(Rel, Base::SymTabSec);
if (!ObjSymbol)
return ObjSymbol.takeError();
Symbol *GraphSymbol = Base::getGraphSymbol(SymbolIndex);
if (!GraphSymbol)
return make_error<StringError>(
formatv("Could not find symbol at given index, did you add it to "
"JITSymbolTable? index: {0}, shndx: {1} Size of table: {2}",
SymbolIndex, (*ObjSymbol)->st_shndx,
Base::GraphSymbols.size()),
inconvertibleErrorCode());
uint32_t Type = Rel.getType(false);
Expected<aarch64::EdgeKind_aarch64> Kind = getRelocationKind(Type);
if (!Kind)
return Kind.takeError();
int64_t Addend = Rel.r_addend;
orc::ExecutorAddr FixupAddress =
orc::ExecutorAddr(FixupSect.sh_addr) + Rel.r_offset;
Edge::OffsetT Offset = FixupAddress - BlockToFix.getAddress();
Edge GE(*Kind, Offset, *GraphSymbol, Addend);
LLVM_DEBUG({
dbgs() << " ";
printEdge(dbgs(), BlockToFix, GE, aarch64::getEdgeKindName(*Kind));
dbgs() << "\n";
});
BlockToFix.addEdge(std::move(GE));
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
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