ca85e37338
Note: What ELF refers to as "TLS", Mach-O seems to refer to as "TLV", i.e. thread-local variables. This diff implements support for TLV relocations that reference defined symbols. On x86_64, TLV relocations are always used with movq opcodes, so for defined TLVs, we don't need to create a synthetic section to store the addresses of the symbols -- we can just convert the `movq` to a `leaq`. One notable quirk of Mach-O's TLVs is that absolute-address relocations inside TLV-defining sections behave differently -- their addresses are no longer absolute, but relative to the start of the target section. (AFAICT, RIP-relative relocations are not allowed in these sections.) Reviewed By: #lld-macho, compnerd, smeenai Differential Revision: https://reviews.llvm.org/D85080
58 lines
1.7 KiB
C++
58 lines
1.7 KiB
C++
//===- InputSection.cpp ---------------------------------------------------===//
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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 "InputSection.h"
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#include "OutputSegment.h"
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#include "Symbols.h"
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#include "Target.h"
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#include "lld/Common/Memory.h"
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#include "llvm/Support/Endian.h"
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using namespace llvm;
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using namespace llvm::MachO;
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using namespace llvm::support;
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using namespace lld;
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using namespace lld::macho;
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std::vector<InputSection *> macho::inputSections;
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uint64_t InputSection::getFileOffset() const {
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return parent->fileOff + outSecFileOff;
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}
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uint64_t InputSection::getVA() const { return parent->addr + outSecOff; }
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void InputSection::writeTo(uint8_t *buf) {
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if (getFileSize() == 0)
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return;
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memcpy(buf, data.data(), data.size());
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for (Reloc &r : relocs) {
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uint64_t va = 0;
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if (auto *s = r.target.dyn_cast<Symbol *>()) {
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va = target->resolveSymbolVA(buf + r.offset, *s, r.type);
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if (isThreadLocalVariables(flags)) {
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// References from thread-local variable sections are treated as
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// offsets relative to the start of the target section, instead of as
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// absolute addresses.
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if (auto *defined = dyn_cast<Defined>(s))
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va -= defined->isec->parent->addr;
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}
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} else if (auto *isec = r.target.dyn_cast<InputSection *>()) {
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va = isec->getVA();
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}
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uint64_t val = va + r.addend;
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if (r.pcrel)
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val -= getVA() + r.offset;
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target->relocateOne(buf + r.offset, r, val);
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}
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}
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