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[JITLink][ELF] Route objects to their matching linker backends based on header info 

Distinguish objects by target properties address size, endian and machine architecture. So far we only
support x86-64 (ELFCLASS64, ELFDATA2LSB, EM_X86_64).

Reviewed By: lhames

Differential Revision: https://reviews.llvm.org/D90860
This commit is contained in:
Stefan Gränitz 2020-12-08 10:53:50 +01:00
parent 2d1b024d06
commit 83b52b5ba2
1 changed files with 44 additions and 11 deletions
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55
llvm/lib/ExecutionEngine/JITLink/ELF.cpp
View File

@ -15,6 +15,7 @@
#include "llvm/BinaryFormat/ELF.h"
#include "llvm/ExecutionEngine/JITLink/ELF_x86_64.h"
#include "llvm/Object/ELF.h"
#include "llvm/Support/Endian.h"
#include "llvm/Support/Format.h"
#include "llvm/Support/MemoryBuffer.h"
@ -27,24 +28,56 @@ using namespace llvm;
namespace llvm {
namespace jitlink {
Expected<uint16_t> readTargetMachineArch(StringRef Buffer) {
const char *Data = Buffer.data();
if (Data[ELF::EI_DATA] == ELF::ELFDATA2LSB) {
if (Data[ELF::EI_CLASS] == ELF::ELFCLASS64) {
if (auto File = llvm::object::ELF64LEFile::create(Buffer)) {
return File->getHeader().e_machine;
} else {
return File.takeError();
}
} else if (Data[ELF::EI_CLASS] == ELF::ELFCLASS32) {
if (auto File = llvm::object::ELF32LEFile::create(Buffer)) {
return File->getHeader().e_machine;
} else {
return File.takeError();
}
}
}
return ELF::EM_NONE;
}
void jitLink_ELF(std::unique_ptr<JITLinkContext> Ctx) {
// We don't want to do full ELF validation here. We just verify it is elf'ish.
// Probably should parse into an elf header when we support more than x86 :)
StringRef Data = Ctx->getObjectBuffer().getBuffer();
if (Data.size() < llvm::ELF::EI_MAG3 + 1) {
StringRef Buffer = Ctx->getObjectBuffer().getBuffer();
if (Buffer.size() < ELF::EI_MAG3 + 1) {
Ctx->notifyFailed(make_error<JITLinkError>("Truncated ELF buffer"));
return;
}
if (!memcmp(Data.data(), llvm::ELF::ElfMagic, strlen(llvm::ELF::ElfMagic))) {
if (Data.data()[llvm::ELF::EI_CLASS] == ELF::ELFCLASS64) {
return jitLink_ELF_x86_64(std::move(Ctx));
}
if (memcmp(Buffer.data(), ELF::ElfMagic, strlen(ELF::ElfMagic)) != 0) {
Ctx->notifyFailed(make_error<JITLinkError>("ELF magic not valid"));
return;
}
Ctx->notifyFailed(make_error<JITLinkError>("ELF magic not valid"));
Expected<uint16_t> TargetMachineArch = readTargetMachineArch(Buffer);
if (!TargetMachineArch) {
Ctx->notifyFailed(TargetMachineArch.takeError());
return;
}
switch (*TargetMachineArch) {
case ELF::EM_X86_64:
jitLink_ELF_x86_64(std::move(Ctx));
return;
default:
Ctx->notifyFailed(make_error<JITLinkError>(
"Unsupported target machine architecture in ELF object " +
Ctx->getObjectBuffer().getBufferIdentifier()));
return;
}
}
} // end namespace jitlink