0d30e92f59
This commit adds support for chained fixups, which were introduced in Apple's late 2020 OS releases. This format replaces the dyld opcodes used for supplying rebase and binding information, and encodes most of that data directly in the memory location that will have the fixup applied. This reduces binary size and is a requirement for page-in linking, which will be available starting with macOS 13. A high-level overview of the format and my implementation can be found in SyntheticSections.h. This feature is currently gated behind the `-fixup_chains` flag, and will be enabled by default for supported targets in a later commit. Like in ld64, lazy binding is disabled when chained fixups are in use, and the `-init_offsets` transformation is performed by default. Differential Revision: https://reviews.llvm.org/D132560
129 lines
4.6 KiB
C++
129 lines
4.6 KiB
C++
//===- ARM64_32.cpp
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//----------------------------------------------------------===//
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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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#include "Arch/ARM64Common.h"
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#include "InputFiles.h"
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#include "Symbols.h"
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#include "SyntheticSections.h"
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#include "Target.h"
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#include "lld/Common/ErrorHandler.h"
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#include "llvm/ADT/SmallVector.h"
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#include "llvm/ADT/StringRef.h"
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#include "llvm/BinaryFormat/MachO.h"
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#include "llvm/Support/Endian.h"
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#include "llvm/Support/MathExtras.h"
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using namespace llvm::MachO;
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using namespace llvm::support::endian;
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using namespace lld;
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using namespace lld::macho;
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namespace {
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struct ARM64_32 : ARM64Common {
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ARM64_32();
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void writeStub(uint8_t *buf, const Symbol &, uint64_t) const override;
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void writeStubHelperHeader(uint8_t *buf) const override;
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void writeStubHelperEntry(uint8_t *buf, const Symbol &,
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uint64_t entryAddr) const override;
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void writeObjCMsgSendStub(uint8_t *buf, Symbol *sym, uint64_t stubsAddr,
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uint64_t stubOffset, uint64_t selrefsVA,
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uint64_t selectorIndex, uint64_t gotAddr,
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uint64_t msgSendIndex) const override;
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};
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} // namespace
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// These are very similar to ARM64's relocation attributes, except that we don't
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// have the BYTE8 flag set.
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static constexpr std::array<RelocAttrs, 11> relocAttrsArray{{
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#define B(x) RelocAttrBits::x
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{"UNSIGNED", B(UNSIGNED) | B(ABSOLUTE) | B(EXTERN) | B(LOCAL) | B(BYTE4)},
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{"SUBTRACTOR", B(SUBTRAHEND) | B(EXTERN) | B(BYTE4)},
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{"BRANCH26", B(PCREL) | B(EXTERN) | B(BRANCH) | B(BYTE4)},
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{"PAGE21", B(PCREL) | B(EXTERN) | B(BYTE4)},
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{"PAGEOFF12", B(ABSOLUTE) | B(EXTERN) | B(BYTE4)},
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{"GOT_LOAD_PAGE21", B(PCREL) | B(EXTERN) | B(GOT) | B(BYTE4)},
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{"GOT_LOAD_PAGEOFF12",
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B(ABSOLUTE) | B(EXTERN) | B(GOT) | B(LOAD) | B(BYTE4)},
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{"POINTER_TO_GOT", B(PCREL) | B(EXTERN) | B(GOT) | B(POINTER) | B(BYTE4)},
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{"TLVP_LOAD_PAGE21", B(PCREL) | B(EXTERN) | B(TLV) | B(BYTE4)},
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{"TLVP_LOAD_PAGEOFF12",
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B(ABSOLUTE) | B(EXTERN) | B(TLV) | B(LOAD) | B(BYTE4)},
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{"ADDEND", B(ADDEND)},
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#undef B
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}};
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// The stub code is fairly similar to ARM64's, except that we load pointers into
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// 32-bit 'w' registers, instead of the 64-bit 'x' ones.
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static constexpr uint32_t stubCode[] = {
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0x90000010, // 00: adrp x16, __la_symbol_ptr@page
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0xb9400210, // 04: ldr w16, [x16, __la_symbol_ptr@pageoff]
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0xd61f0200, // 08: br x16
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};
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void ARM64_32::writeStub(uint8_t *buf8, const Symbol &sym,
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uint64_t pointerVA) const {
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::writeStub(buf8, stubCode, sym, pointerVA);
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}
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static constexpr uint32_t stubHelperHeaderCode[] = {
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0x90000011, // 00: adrp x17, _dyld_private@page
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0x91000231, // 04: add x17, x17, _dyld_private@pageoff
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0xa9bf47f0, // 08: stp x16/x17, [sp, #-16]!
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0x90000010, // 0c: adrp x16, dyld_stub_binder@page
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0xb9400210, // 10: ldr w16, [x16, dyld_stub_binder@pageoff]
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0xd61f0200, // 14: br x16
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};
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void ARM64_32::writeStubHelperHeader(uint8_t *buf8) const {
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::writeStubHelperHeader<ILP32>(buf8, stubHelperHeaderCode);
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}
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static constexpr uint32_t stubHelperEntryCode[] = {
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0x18000050, // 00: ldr w16, l0
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0x14000000, // 04: b stubHelperHeader
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0x00000000, // 08: l0: .long 0
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};
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void ARM64_32::writeStubHelperEntry(uint8_t *buf8, const Symbol &sym,
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uint64_t entryVA) const {
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::writeStubHelperEntry(buf8, stubHelperEntryCode, sym, entryVA);
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}
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void ARM64_32::writeObjCMsgSendStub(uint8_t *buf, Symbol *sym,
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uint64_t stubsAddr, uint64_t stubOffset,
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uint64_t selrefsVA, uint64_t selectorIndex,
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uint64_t gotAddr,
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uint64_t msgSendIndex) const {
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fatal("TODO: implement this");
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}
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ARM64_32::ARM64_32() : ARM64Common(ILP32()) {
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cpuType = CPU_TYPE_ARM64_32;
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cpuSubtype = CPU_SUBTYPE_ARM64_V8;
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modeDwarfEncoding = 0x04000000; // UNWIND_ARM_MODE_DWARF
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subtractorRelocType = GENERIC_RELOC_INVALID; // FIXME
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unsignedRelocType = GENERIC_RELOC_INVALID; // FIXME
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stubSize = sizeof(stubCode);
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stubHelperHeaderSize = sizeof(stubHelperHeaderCode);
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stubHelperEntrySize = sizeof(stubHelperEntryCode);
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relocAttrs = {relocAttrsArray.data(), relocAttrsArray.size()};
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}
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TargetInfo *macho::createARM64_32TargetInfo() {
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static ARM64_32 t;
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return &t;
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}
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