74871cdad7
Summary: llvm-mc emits `__bss` sections with an offset of zero, but we weren't expecting that in our input, so we were copying non-zero data from the start of the file and putting it in `__bss`, with obviously undesirable runtime results. (It appears that the kernel will copy those nonzero bytes as long as the offset is nonzero, regardless of whether S_ZERO_FILL is set.) I debated on whether to make a special ZeroFillSection -- separate from a regular InputSection -- but it seemed like too much work for now. But I'm happy to refactor if anyone feels strongly about having it as a separate class. Depends on D80857. Reviewers: ruiu, pcc, MaskRay, smeenai, alexshap, gkm, Ktwu, christylee Reviewed By: smeenai Subscribers: llvm-commits Tags: #llvm Differential Revision: https://reviews.llvm.org/D80859
75 lines
1.8 KiB
C++
75 lines
1.8 KiB
C++
//===- InputSection.h -------------------------------------------*- C++ -*-===//
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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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#ifndef LLD_MACHO_INPUT_SECTION_H
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#define LLD_MACHO_INPUT_SECTION_H
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#include "lld/Common/LLVM.h"
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#include "llvm/ADT/ArrayRef.h"
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#include "llvm/ADT/PointerUnion.h"
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#include "llvm/BinaryFormat/MachO.h"
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namespace lld {
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namespace macho {
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class InputFile;
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class InputSection;
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class OutputSection;
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class Symbol;
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struct Reloc {
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uint8_t type;
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bool pcrel;
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uint8_t length;
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// The offset from the start of the subsection that this relocation belongs
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// to.
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uint32_t offset;
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// Adding this offset to the address of the target symbol or subsection gives
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// the destination that this relocation refers to.
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uint64_t addend;
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llvm::PointerUnion<Symbol *, InputSection *> target;
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};
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inline bool isZeroFill(uint8_t flags) {
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return (flags & llvm::MachO::SECTION_TYPE) == llvm::MachO::S_ZEROFILL;
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}
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class InputSection {
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public:
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virtual ~InputSection() = default;
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virtual uint64_t getSize() const { return data.size(); }
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virtual uint64_t getFileSize() const {
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return isZeroFill(flags) ? 0 : getSize();
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}
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uint64_t getFileOffset() const;
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uint64_t getVA() const;
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virtual void writeTo(uint8_t *buf);
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InputFile *file = nullptr;
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StringRef name;
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StringRef segname;
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OutputSection *parent = nullptr;
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uint64_t outSecOff = 0;
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uint64_t outSecFileOff = 0;
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uint32_t align = 1;
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uint32_t flags = 0;
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ArrayRef<uint8_t> data;
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std::vector<Reloc> relocs;
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};
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extern std::vector<InputSection *> inputSections;
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} // namespace macho
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} // namespace lld
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#endif
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