57 lines
1.8 KiB
C++
57 lines
1.8 KiB
C++
//===- Thunks.h --------------------------------------------------------===//
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//
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// The LLVM Linker
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLD_ELF_THUNKS_H
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#define LLD_ELF_THUNKS_H
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#include "Relocations.h"
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namespace lld {
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namespace elf {
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class SymbolBody;
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template <class ELFT> class InputSection;
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// Class to describe an instance of a Thunk.
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// A Thunk is a code-sequence inserted by the linker in between a caller and
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// the callee. The relocation to the callee is redirected to the Thunk, which
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// after executing transfers control to the callee. Typical uses of Thunks
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// include transferring control from non-pi to pi and changing state on
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// targets like ARM.
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//
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// Thunks can be created for DefinedRegular and Shared Symbols. The Thunk
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// is stored in a field of the Symbol Destination.
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// Thunks to be written to an InputSection are recorded by the InputSection.
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template <class ELFT> class Thunk {
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typedef typename ELFT::uint uintX_t;
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public:
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Thunk(const SymbolBody &Destination, const InputSection<ELFT> &Owner);
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virtual ~Thunk();
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virtual uint32_t size() const { return 0; }
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virtual void writeTo(uint8_t *Buf) const {}
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uintX_t getVA() const;
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protected:
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const SymbolBody &Destination;
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const InputSection<ELFT> &Owner;
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uint64_t Offset;
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};
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// For a Relocation to symbol S from InputSection Src, create a Thunk and
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// update the fields of S and the InputSection that the Thunk body will be
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// written to. At present there are implementations for ARM and Mips Thunks.
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template <class ELFT>
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void addThunk(uint32_t RelocType, SymbolBody &S, InputSection<ELFT> &Src);
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} // namespace elf
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} // namespace lld
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#endif
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