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3a9eef1670
This is what InputSectionBase<ELFT>::relocate does and we need to be consistent. The other option would be to be more explicit about which relocations are signed and which are not, and sign extend only when appropriated. That would require extending the target interface. llvm-svn: 280366
270 lines
9.3 KiB
C++
270 lines
9.3 KiB
C++
//===- Thunks.cpp --------------------------------------------------------===//
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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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//
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// This file contains Thunk subclasses.
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//
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// A thunk is a small piece of code written after an input section
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// which is used to jump between "incompatible" functions
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// such as MIPS PIC and non-PIC or ARM non-Thumb and Thumb functions.
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//
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// If a jump target is too far and its address doesn't fit to a
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// short jump instruction, we need to create a thunk too, but we
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// haven't supported it yet.
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//
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// i386 and x86-64 don't need thunks.
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//
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//===---------------------------------------------------------------------===//
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#include "Thunks.h"
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#include "Error.h"
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#include "InputFiles.h"
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#include "InputSection.h"
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#include "OutputSections.h"
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#include "Symbols.h"
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#include "Target.h"
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#include "llvm/Support/Allocator.h"
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#include "llvm/Object/ELF.h"
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#include "llvm/Support/ELF.h"
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#include "llvm/Support/Endian.h"
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using namespace llvm;
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using namespace llvm::object;
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using namespace llvm::support::endian;
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using namespace llvm::ELF;
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namespace lld {
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namespace elf {
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namespace {
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// Specific ARM Thunk implementations. The naming convention is:
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// Source State, TargetState, Target Requirement, ABS or PI, Range
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template <class ELFT>
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class ARMToThumbV7ABSLongThunk final : public Thunk<ELFT> {
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public:
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ARMToThumbV7ABSLongThunk(const SymbolBody &Dest,
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const InputSection<ELFT> &Owner)
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: Thunk<ELFT>(Dest, Owner) {}
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uint32_t size() const override { return 12; }
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void writeTo(uint8_t *Buf) const override;
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};
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template <class ELFT> class ARMToThumbV7PILongThunk final : public Thunk<ELFT> {
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public:
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ARMToThumbV7PILongThunk(const SymbolBody &Dest,
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const InputSection<ELFT> &Owner)
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: Thunk<ELFT>(Dest, Owner) {}
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uint32_t size() const override { return 16; }
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void writeTo(uint8_t *Buf) const override;
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};
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template <class ELFT>
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class ThumbToARMV7ABSLongThunk final : public Thunk<ELFT> {
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public:
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ThumbToARMV7ABSLongThunk(const SymbolBody &Dest,
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const InputSection<ELFT> &Owner)
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: Thunk<ELFT>(Dest, Owner) {}
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uint32_t size() const override { return 10; }
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void writeTo(uint8_t *Buf) const override;
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};
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template <class ELFT> class ThumbToARMV7PILongThunk final : public Thunk<ELFT> {
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public:
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ThumbToARMV7PILongThunk(const SymbolBody &Dest,
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const InputSection<ELFT> &Owner)
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: Thunk<ELFT>(Dest, Owner) {}
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uint32_t size() const override { return 12; }
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void writeTo(uint8_t *Buf) const override;
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};
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// MIPS LA25 thunk
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template <class ELFT> class MipsThunk final : public Thunk<ELFT> {
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public:
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MipsThunk(const SymbolBody &Dest, const InputSection<ELFT> &Owner)
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: Thunk<ELFT>(Dest, Owner) {}
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uint32_t size() const override { return 16; }
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void writeTo(uint8_t *Buf) const override;
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};
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} // anonymous namespace
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// ARM Target Thunks
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template <class ELFT> static uint64_t getARMThunkDestVA(const SymbolBody &S) {
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uint64_t V = S.isInPlt() ? S.getPltVA<ELFT>() : S.getVA<ELFT>();
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return SignExtend64<32>(V);
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}
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template <class ELFT>
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void ARMToThumbV7ABSLongThunk<ELFT>::writeTo(uint8_t *Buf) const {
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const uint8_t Data[] = {
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0x00, 0xc0, 0x00, 0xe3, // movw ip,:lower16:S
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0x00, 0xc0, 0x40, 0xe3, // movt ip,:upper16:S
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0x1c, 0xff, 0x2f, 0xe1, // bx ip
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};
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uint64_t S = getARMThunkDestVA<ELFT>(this->Destination);
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memcpy(Buf, Data, sizeof(Data));
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Target->relocateOne(Buf, R_ARM_MOVW_ABS_NC, S);
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Target->relocateOne(Buf + 4, R_ARM_MOVT_ABS, S);
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}
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template <class ELFT>
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void ThumbToARMV7ABSLongThunk<ELFT>::writeTo(uint8_t *Buf) const {
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const uint8_t Data[] = {
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0x40, 0xf2, 0x00, 0x0c, // movw ip, :lower16:S
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0xc0, 0xf2, 0x00, 0x0c, // movt ip, :upper16:S
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0x60, 0x47, // bx ip
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};
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uint64_t S = getARMThunkDestVA<ELFT>(this->Destination);
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memcpy(Buf, Data, sizeof(Data));
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Target->relocateOne(Buf, R_ARM_THM_MOVW_ABS_NC, S);
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Target->relocateOne(Buf + 4, R_ARM_THM_MOVT_ABS, S);
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}
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template <class ELFT>
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void ARMToThumbV7PILongThunk<ELFT>::writeTo(uint8_t *Buf) const {
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const uint8_t Data[] = {
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0xf0, 0xcf, 0x0f, 0xe3, // P: movw ip,:lower16:S - (P + (L1-P) +8)
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0x00, 0xc0, 0x40, 0xe3, // movt ip,:upper16:S - (P + (L1-P+4) +8)
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0x0f, 0xc0, 0x8c, 0xe0, // L1: add ip, ip, pc
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0x1c, 0xff, 0x2f, 0xe1, // bx r12
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};
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uint64_t S = getARMThunkDestVA<ELFT>(this->Destination);
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uint64_t P = this->getVA();
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memcpy(Buf, Data, sizeof(Data));
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Target->relocateOne(Buf, R_ARM_MOVW_PREL_NC, S - P - 16);
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Target->relocateOne(Buf + 4, R_ARM_MOVT_PREL, S - P - 12);
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}
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template <class ELFT>
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void ThumbToARMV7PILongThunk<ELFT>::writeTo(uint8_t *Buf) const {
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const uint8_t Data[] = {
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0x4f, 0xf6, 0xf4, 0x7c, // P: movw ip,:lower16:S - (P + (L1-P) + 4)
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0xc0, 0xf2, 0x00, 0x0c, // movt ip,:upper16:S - (P + (L1-P+4) + 4)
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0xfc, 0x44, // L1: add r12, pc
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0x60, 0x47, // bx r12
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};
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uint64_t S = getARMThunkDestVA<ELFT>(this->Destination);
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uint64_t P = this->getVA();
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memcpy(Buf, Data, sizeof(Data));
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Target->relocateOne(Buf, R_ARM_THM_MOVW_PREL_NC, S - P - 12);
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Target->relocateOne(Buf + 4, R_ARM_THM_MOVT_PREL, S - P - 8);
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}
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// Write MIPS LA25 thunk code to call PIC function from the non-PIC one.
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template <class ELFT> void MipsThunk<ELFT>::writeTo(uint8_t *Buf) const {
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const endianness E = ELFT::TargetEndianness;
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uint64_t S = this->Destination.template getVA<ELFT>();
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write32<E>(Buf, 0x3c190000); // lui $25, %hi(func)
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write32<E>(Buf + 4, 0x08000000 | (S >> 2)); // j func
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write32<E>(Buf + 8, 0x27390000); // addiu $25, $25, %lo(func)
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write32<E>(Buf + 12, 0x00000000); // nop
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Target->relocateOne(Buf, R_MIPS_HI16, S);
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Target->relocateOne(Buf + 8, R_MIPS_LO16, S);
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}
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template <class ELFT>
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Thunk<ELFT>::Thunk(const SymbolBody &D, const InputSection<ELFT> &O)
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: Destination(D), Owner(O), Offset(O.getThunkOff() + O.getThunksSize()) {}
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template <class ELFT> typename ELFT::uint Thunk<ELFT>::getVA() const {
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return Owner.OutSec->getVA() + Owner.OutSecOff + Offset;
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}
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template <class ELFT> Thunk<ELFT>::~Thunk() {}
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// Creates a thunk for Thumb-ARM interworking.
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template <class ELFT>
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static Thunk<ELFT> *createThunkArm(uint32_t Reloc, SymbolBody &S,
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InputSection<ELFT> &IS) {
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// ARM relocations need ARM to Thumb interworking Thunks.
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// Thumb relocations need Thumb to ARM relocations.
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// Use position independent Thunks if we require position independent code.
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BumpPtrAllocator &Alloc = IS.getFile()->Alloc;
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switch (Reloc) {
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case R_ARM_PC24:
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case R_ARM_PLT32:
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case R_ARM_JUMP24:
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if (Config->Pic)
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return new (Alloc) ARMToThumbV7PILongThunk<ELFT>(S, IS);
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return new (Alloc) ARMToThumbV7ABSLongThunk<ELFT>(S, IS);
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case R_ARM_THM_JUMP19:
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case R_ARM_THM_JUMP24:
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if (Config->Pic)
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return new (Alloc) ThumbToARMV7PILongThunk<ELFT>(S, IS);
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return new (Alloc) ThumbToARMV7ABSLongThunk<ELFT>(S, IS);
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}
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fatal("unrecognized relocation type");
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}
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template <class ELFT>
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static void addThunkARM(uint32_t Reloc, SymbolBody &S, InputSection<ELFT> &IS) {
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// Only one Thunk supported per symbol.
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if (S.hasThunk<ELFT>())
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return;
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// ARM Thunks are added to the same InputSection as the relocation. This
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// isn't strictly necessary but it makes it more likely that a limited range
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// branch can reach the Thunk, and it makes Thunks to the PLT section easier
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Thunk<ELFT> *T = createThunkArm(Reloc, S, IS);
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IS.addThunk(T);
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if (auto *Sym = dyn_cast<DefinedRegular<ELFT>>(&S))
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Sym->ThunkData = T;
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else if (auto *Sym = dyn_cast<SharedSymbol<ELFT>>(&S))
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Sym->ThunkData = T;
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else
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fatal("symbol not DefinedRegular or Shared");
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}
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template <class ELFT>
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static void addThunkMips(uint32_t RelocType, SymbolBody &S,
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InputSection<ELFT> &IS) {
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// Only one Thunk supported per symbol.
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if (S.hasThunk<ELFT>())
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return;
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// Mips Thunks are added to the InputSection defining S.
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auto *R = cast<DefinedRegular<ELFT>>(&S);
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auto *Sec = cast<InputSection<ELFT>>(R->Section);
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auto *T = new (IS.getFile()->Alloc) MipsThunk<ELFT>(S, *Sec);
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Sec->addThunk(T);
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R->ThunkData = T;
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}
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template <class ELFT>
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void addThunk(uint32_t RelocType, SymbolBody &S, InputSection<ELFT> &IS) {
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if (Config->EMachine == EM_ARM)
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addThunkARM<ELFT>(RelocType, S, IS);
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else if (Config->EMachine == EM_MIPS)
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addThunkMips<ELFT>(RelocType, S, IS);
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else
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llvm_unreachable("add Thunk only supported for ARM and Mips");
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}
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template void addThunk<ELF32LE>(uint32_t, SymbolBody &,
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InputSection<ELF32LE> &);
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template void addThunk<ELF32BE>(uint32_t, SymbolBody &,
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InputSection<ELF32BE> &);
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template void addThunk<ELF64LE>(uint32_t, SymbolBody &,
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InputSection<ELF64LE> &);
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template void addThunk<ELF64BE>(uint32_t, SymbolBody &,
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InputSection<ELF64BE> &);
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template class Thunk<ELF32LE>;
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template class Thunk<ELF32BE>;
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template class Thunk<ELF64LE>;
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template class Thunk<ELF64BE>;
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} // namespace elf
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} // namespace lld
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