5c1d160cd9
This first version lays the foundations for AArch32 support in JITLink. ELFLinkGraphBuilder_aarch32 processes REL-type relocations and populates LinkGraphs from ELF object files for both big- and little-endian systems. The ArmCfg member controls subarchitecture-specific details throughout the linking process (i.e. it's passed to ELFJITLinker_aarch32). Relocation types follow the ABI documentation's division into classes: Data (endian-sensitive), Arm (32-bit little-endian) and Thumb (2x 16-bit little-endian, "Thumb32" in the docs). The implementation of instruction encoding/decoding for relocation resolution is implemented symmetrically and is testable in isolation (see AArch32 category in JITLinkTests). Callable Thumb functions are marked with a ThumbSymbol target-flag and stored in the LinkGraph with their real addresses. The thumb-bit is added back in when the owning JITDylib requests the address for such a symbol. The StubsManager can generate (absolute) Thumb-state stubs for branch range extensions on v7+ targets. Proper GOT/PLT handling is not yet implemented. This patch is based on the backend implementation in ez-clang and has just enough functionality to model the infrastructure and link a Thumb function `main()` that calls `printf()` to dump "Hello Arm!" on Armv7a. It was tested on Raspberry Pi with 32-bit Raspbian OS. Reviewed By: lhames Differential Revision: https://reviews.llvm.org/D144083
126 lines
3.9 KiB
C++
126 lines
3.9 KiB
C++
//===-------------- ELF.cpp - JIT linker function for ELF -------------===//
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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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//
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// ELF jit-link function.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/ExecutionEngine/JITLink/ELF.h"
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#include "llvm/BinaryFormat/ELF.h"
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#include "llvm/ExecutionEngine/JITLink/ELF_aarch32.h"
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#include "llvm/ExecutionEngine/JITLink/ELF_aarch64.h"
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#include "llvm/ExecutionEngine/JITLink/ELF_i386.h"
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#include "llvm/ExecutionEngine/JITLink/ELF_loongarch.h"
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#include "llvm/ExecutionEngine/JITLink/ELF_riscv.h"
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#include "llvm/ExecutionEngine/JITLink/ELF_x86_64.h"
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#include "llvm/Object/ELF.h"
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#include "llvm/Support/Endian.h"
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#include "llvm/Support/Format.h"
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#include "llvm/Support/MemoryBuffer.h"
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#include <cstring>
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using namespace llvm;
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#define DEBUG_TYPE "jitlink"
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namespace llvm {
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namespace jitlink {
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Expected<uint16_t> readTargetMachineArch(StringRef Buffer) {
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const char *Data = Buffer.data();
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if (Data[ELF::EI_DATA] == ELF::ELFDATA2LSB) {
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if (Data[ELF::EI_CLASS] == ELF::ELFCLASS64) {
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if (auto File = llvm::object::ELF64LEFile::create(Buffer)) {
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return File->getHeader().e_machine;
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} else {
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return File.takeError();
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}
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} else if (Data[ELF::EI_CLASS] == ELF::ELFCLASS32) {
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if (auto File = llvm::object::ELF32LEFile::create(Buffer)) {
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return File->getHeader().e_machine;
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} else {
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return File.takeError();
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}
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}
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}
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return ELF::EM_NONE;
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}
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Expected<std::unique_ptr<LinkGraph>>
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createLinkGraphFromELFObject(MemoryBufferRef ObjectBuffer) {
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StringRef Buffer = ObjectBuffer.getBuffer();
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if (Buffer.size() < ELF::EI_MAG3 + 1)
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return make_error<JITLinkError>("Truncated ELF buffer");
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if (memcmp(Buffer.data(), ELF::ElfMagic, strlen(ELF::ElfMagic)) != 0)
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return make_error<JITLinkError>("ELF magic not valid");
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Expected<uint16_t> TargetMachineArch = readTargetMachineArch(Buffer);
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if (!TargetMachineArch)
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return TargetMachineArch.takeError();
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switch (*TargetMachineArch) {
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case ELF::EM_AARCH64:
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return createLinkGraphFromELFObject_aarch64(ObjectBuffer);
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case ELF::EM_ARM:
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return createLinkGraphFromELFObject_aarch32(ObjectBuffer);
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case ELF::EM_LOONGARCH:
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return createLinkGraphFromELFObject_loongarch(ObjectBuffer);
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case ELF::EM_RISCV:
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return createLinkGraphFromELFObject_riscv(ObjectBuffer);
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case ELF::EM_X86_64:
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return createLinkGraphFromELFObject_x86_64(ObjectBuffer);
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case ELF::EM_386:
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return createLinkGraphFromELFObject_i386(ObjectBuffer);
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default:
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return make_error<JITLinkError>(
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"Unsupported target machine architecture in ELF object " +
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ObjectBuffer.getBufferIdentifier());
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}
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}
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void link_ELF(std::unique_ptr<LinkGraph> G,
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std::unique_ptr<JITLinkContext> Ctx) {
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switch (G->getTargetTriple().getArch()) {
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case Triple::aarch64:
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link_ELF_aarch64(std::move(G), std::move(Ctx));
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return;
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case Triple::arm:
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case Triple::armeb:
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case Triple::thumb:
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case Triple::thumbeb:
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link_ELF_aarch32(std::move(G), std::move(Ctx));
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return;
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case Triple::loongarch32:
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case Triple::loongarch64:
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link_ELF_loongarch(std::move(G), std::move(Ctx));
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return;
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case Triple::riscv32:
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case Triple::riscv64:
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link_ELF_riscv(std::move(G), std::move(Ctx));
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return;
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case Triple::x86_64:
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link_ELF_x86_64(std::move(G), std::move(Ctx));
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return;
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case Triple::x86:
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link_ELF_i386(std::move(G), std::move(Ctx));
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return;
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default:
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Ctx->notifyFailed(make_error<JITLinkError>(
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"Unsupported target machine architecture in ELF link graph " +
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G->getName()));
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return;
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}
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}
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} // end namespace jitlink
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} // end namespace llvm
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