| //===- X86_64.cpp ---------------------------------------------------------===// |
| // |
| // 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 |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "InputFiles.h" |
| #include "Symbols.h" |
| #include "SyntheticSections.h" |
| #include "Target.h" |
| |
| #include "lld/Common/ErrorHandler.h" |
| #include "mach-o/compact_unwind_encoding.h" |
| #include "llvm/BinaryFormat/MachO.h" |
| #include "llvm/Support/Endian.h" |
| |
| using namespace llvm::MachO; |
| using namespace llvm::support::endian; |
| using namespace lld; |
| using namespace lld::macho; |
| |
| namespace { |
| |
| struct X86_64 : TargetInfo { |
| X86_64(); |
| |
| int64_t getEmbeddedAddend(MemoryBufferRef, uint64_t offset, |
| const relocation_info) const override; |
| void relocateOne(uint8_t *loc, const Reloc &, uint64_t va, |
| uint64_t relocVA) const override; |
| |
| void writeStub(uint8_t *buf, const Symbol &, |
| uint64_t pointerVA) const override; |
| void writeStubHelperHeader(uint8_t *buf) const override; |
| void writeStubHelperEntry(uint8_t *buf, const Symbol &, |
| uint64_t entryAddr) const override; |
| |
| void writeObjCMsgSendStub(uint8_t *buf, Symbol *sym, uint64_t stubsAddr, |
| uint64_t &stubOffset, uint64_t selrefVA, |
| Symbol *objcMsgSend) const override; |
| |
| void relaxGotLoad(uint8_t *loc, uint8_t type) const override; |
| uint64_t getPageSize() const override { return 4 * 1024; } |
| |
| void handleDtraceReloc(const Symbol *sym, const Reloc &r, |
| uint8_t *loc) const override; |
| }; |
| } // namespace |
| |
| static constexpr std::array<RelocAttrs, 10> relocAttrsArray{{ |
| #define B(x) RelocAttrBits::x |
| {"UNSIGNED", |
| B(UNSIGNED) | B(ABSOLUTE) | B(EXTERN) | B(LOCAL) | B(BYTE4) | B(BYTE8)}, |
| {"SIGNED", B(PCREL) | B(EXTERN) | B(LOCAL) | B(BYTE4)}, |
| {"BRANCH", B(PCREL) | B(EXTERN) | B(BRANCH) | B(BYTE4)}, |
| {"GOT_LOAD", B(PCREL) | B(EXTERN) | B(GOT) | B(LOAD) | B(BYTE4)}, |
| {"GOT", B(PCREL) | B(EXTERN) | B(GOT) | B(POINTER) | B(BYTE4)}, |
| {"SUBTRACTOR", B(SUBTRAHEND) | B(EXTERN) | B(BYTE4) | B(BYTE8)}, |
| {"SIGNED_1", B(PCREL) | B(EXTERN) | B(LOCAL) | B(BYTE4)}, |
| {"SIGNED_2", B(PCREL) | B(EXTERN) | B(LOCAL) | B(BYTE4)}, |
| {"SIGNED_4", B(PCREL) | B(EXTERN) | B(LOCAL) | B(BYTE4)}, |
| {"TLV", B(PCREL) | B(EXTERN) | B(TLV) | B(LOAD) | B(BYTE4)}, |
| #undef B |
| }}; |
| |
| static int pcrelOffset(uint8_t type) { |
| switch (type) { |
| case X86_64_RELOC_SIGNED_1: |
| return 1; |
| case X86_64_RELOC_SIGNED_2: |
| return 2; |
| case X86_64_RELOC_SIGNED_4: |
| return 4; |
| default: |
| return 0; |
| } |
| } |
| |
| int64_t X86_64::getEmbeddedAddend(MemoryBufferRef mb, uint64_t offset, |
| relocation_info rel) const { |
| auto *buf = reinterpret_cast<const uint8_t *>(mb.getBufferStart()); |
| const uint8_t *loc = buf + offset + rel.r_address; |
| |
| switch (rel.r_length) { |
| case 2: |
| return static_cast<int32_t>(read32le(loc)) + pcrelOffset(rel.r_type); |
| case 3: |
| return read64le(loc) + pcrelOffset(rel.r_type); |
| default: |
| llvm_unreachable("invalid r_length"); |
| } |
| } |
| |
| void X86_64::relocateOne(uint8_t *loc, const Reloc &r, uint64_t value, |
| uint64_t relocVA) const { |
| if (r.pcrel) { |
| uint64_t pc = relocVA + 4 + pcrelOffset(r.type); |
| value -= pc; |
| } |
| |
| switch (r.length) { |
| case 2: |
| if (r.type == X86_64_RELOC_UNSIGNED) |
| checkUInt(loc, r, value, 32); |
| else |
| checkInt(loc, r, value, 32); |
| write32le(loc, value); |
| break; |
| case 3: |
| write64le(loc, value); |
| break; |
| default: |
| llvm_unreachable("invalid r_length"); |
| } |
| } |
| |
| // The following methods emit a number of assembly sequences with RIP-relative |
| // addressing. Note that RIP-relative addressing on X86-64 has the RIP pointing |
| // to the next instruction, not the current instruction, so we always have to |
| // account for the current instruction's size when calculating offsets. |
| // writeRipRelative helps with that. |
| // |
| // bufAddr: The virtual address corresponding to buf[0]. |
| // bufOff: The offset within buf of the next instruction. |
| // destAddr: The destination address that the current instruction references. |
| static void writeRipRelative(SymbolDiagnostic d, uint8_t *buf, uint64_t bufAddr, |
| uint64_t bufOff, uint64_t destAddr) { |
| uint64_t rip = bufAddr + bufOff; |
| checkInt(buf, d, destAddr - rip, 32); |
| // For the instructions we care about, the RIP-relative address is always |
| // stored in the last 4 bytes of the instruction. |
| write32le(buf + bufOff - 4, destAddr - rip); |
| } |
| |
| static constexpr uint8_t stub[] = { |
| 0xff, 0x25, 0, 0, 0, 0, // jmpq *__la_symbol_ptr(%rip) |
| }; |
| |
| void X86_64::writeStub(uint8_t *buf, const Symbol &sym, |
| uint64_t pointerVA) const { |
| memcpy(buf, stub, 2); // just copy the two nonzero bytes |
| uint64_t stubAddr = in.stubs->addr + sym.stubsIndex * sizeof(stub); |
| writeRipRelative({&sym, "stub"}, buf, stubAddr, sizeof(stub), pointerVA); |
| } |
| |
| static constexpr uint8_t stubHelperHeader[] = { |
| 0x4c, 0x8d, 0x1d, 0, 0, 0, 0, // 0x0: leaq ImageLoaderCache(%rip), %r11 |
| 0x41, 0x53, // 0x7: pushq %r11 |
| 0xff, 0x25, 0, 0, 0, 0, // 0x9: jmpq *dyld_stub_binder@GOT(%rip) |
| 0x90, // 0xf: nop |
| }; |
| |
| void X86_64::writeStubHelperHeader(uint8_t *buf) const { |
| memcpy(buf, stubHelperHeader, sizeof(stubHelperHeader)); |
| SymbolDiagnostic d = {nullptr, "stub helper header"}; |
| writeRipRelative(d, buf, in.stubHelper->addr, 7, |
| in.imageLoaderCache->getVA()); |
| writeRipRelative(d, buf, in.stubHelper->addr, 0xf, |
| in.got->addr + |
| in.stubHelper->stubBinder->gotIndex * LP64::wordSize); |
| } |
| |
| static constexpr uint8_t stubHelperEntry[] = { |
| 0x68, 0, 0, 0, 0, // 0x0: pushq <bind offset> |
| 0xe9, 0, 0, 0, 0, // 0x5: jmp <__stub_helper> |
| }; |
| |
| void X86_64::writeStubHelperEntry(uint8_t *buf, const Symbol &sym, |
| uint64_t entryAddr) const { |
| memcpy(buf, stubHelperEntry, sizeof(stubHelperEntry)); |
| write32le(buf + 1, sym.lazyBindOffset); |
| writeRipRelative({&sym, "stub helper"}, buf, entryAddr, |
| sizeof(stubHelperEntry), in.stubHelper->addr); |
| } |
| |
| static constexpr uint8_t objcStubsFastCode[] = { |
| 0x48, 0x8b, 0x35, 0, 0, 0, 0, // 0x0: movq selrefs@selector(%rip), %rsi |
| 0xff, 0x25, 0, 0, 0, 0, // 0x7: jmpq *_objc_msgSend@GOT(%rip) |
| }; |
| |
| void X86_64::writeObjCMsgSendStub(uint8_t *buf, Symbol *sym, uint64_t stubsAddr, |
| uint64_t &stubOffset, uint64_t selrefVA, |
| Symbol *objcMsgSend) const { |
| uint64_t objcMsgSendAddr = in.got->addr; |
| uint64_t objcMsgSendIndex = objcMsgSend->gotIndex; |
| |
| memcpy(buf, objcStubsFastCode, sizeof(objcStubsFastCode)); |
| SymbolDiagnostic d = {sym, sym->getName()}; |
| uint64_t stubAddr = stubsAddr + stubOffset; |
| writeRipRelative(d, buf, stubAddr, 7, selrefVA); |
| writeRipRelative(d, buf, stubAddr, 0xd, |
| objcMsgSendAddr + objcMsgSendIndex * LP64::wordSize); |
| stubOffset += target->objcStubsFastSize; |
| } |
| |
| void X86_64::relaxGotLoad(uint8_t *loc, uint8_t type) const { |
| // Convert MOVQ to LEAQ |
| if (loc[-2] != 0x8b) |
| error(getRelocAttrs(type).name + " reloc requires MOVQ instruction"); |
| loc[-2] = 0x8d; |
| } |
| |
| X86_64::X86_64() : TargetInfo(LP64()) { |
| cpuType = CPU_TYPE_X86_64; |
| cpuSubtype = CPU_SUBTYPE_X86_64_ALL; |
| |
| modeDwarfEncoding = UNWIND_X86_MODE_DWARF; |
| subtractorRelocType = X86_64_RELOC_SUBTRACTOR; |
| unsignedRelocType = X86_64_RELOC_UNSIGNED; |
| |
| stubSize = sizeof(stub); |
| stubHelperHeaderSize = sizeof(stubHelperHeader); |
| stubHelperEntrySize = sizeof(stubHelperEntry); |
| |
| objcStubsFastSize = sizeof(objcStubsFastCode); |
| objcStubsFastAlignment = 1; |
| |
| relocAttrs = {relocAttrsArray.data(), relocAttrsArray.size()}; |
| } |
| |
| TargetInfo *macho::createX86_64TargetInfo() { |
| static X86_64 t; |
| return &t; |
| } |
| |
| void X86_64::handleDtraceReloc(const Symbol *sym, const Reloc &r, |
| uint8_t *loc) const { |
| assert(r.type == X86_64_RELOC_BRANCH); |
| |
| if (config->outputType == MH_OBJECT) |
| return; |
| |
| if (sym->getName().starts_with("___dtrace_probe")) { |
| // change call site to a NOP |
| loc[-1] = 0x90; |
| write32le(loc, 0x00401F0F); |
| } else if (sym->getName().starts_with("___dtrace_isenabled")) { |
| // change call site to a clear eax |
| loc[-1] = 0x33; |
| write32le(loc, 0x909090C0); |
| } else { |
| error("Unrecognized dtrace symbol prefix: " + toString(*sym)); |
| } |
| } |