forked from OSchip/llvm-project
280 lines
9.3 KiB
C++
280 lines
9.3 KiB
C++
//===- Thunks.cpp --------------------------------------------------------===//
|
|
//
|
|
// The LLVM Linker
|
|
//
|
|
// This file is distributed under the University of Illinois Open Source
|
|
// License. See LICENSE.TXT for details.
|
|
//
|
|
//===---------------------------------------------------------------------===//
|
|
//
|
|
// This file contains Thunk subclasses.
|
|
//
|
|
// A thunk is a small piece of code written after an input section
|
|
// which is used to jump between "incompatible" functions
|
|
// such as MIPS PIC and non-PIC or ARM non-Thumb and Thumb functions.
|
|
//
|
|
// If a jump target is too far and its address doesn't fit to a
|
|
// short jump instruction, we need to create a thunk too, but we
|
|
// haven't supported it yet.
|
|
//
|
|
// i386 and x86-64 don't need thunks.
|
|
//
|
|
//===---------------------------------------------------------------------===//
|
|
|
|
#include "Thunks.h"
|
|
#include "Config.h"
|
|
#include "Error.h"
|
|
#include "InputSection.h"
|
|
#include "Memory.h"
|
|
#include "OutputSections.h"
|
|
#include "Symbols.h"
|
|
#include "SyntheticSections.h"
|
|
#include "Target.h"
|
|
#include "llvm/BinaryFormat/ELF.h"
|
|
#include "llvm/Support/Casting.h"
|
|
#include "llvm/Support/Endian.h"
|
|
#include "llvm/Support/ErrorHandling.h"
|
|
#include "llvm/Support/MathExtras.h"
|
|
#include <cstdint>
|
|
#include <cstring>
|
|
|
|
using namespace llvm;
|
|
using namespace llvm::object;
|
|
using namespace llvm::support::endian;
|
|
using namespace llvm::ELF;
|
|
|
|
namespace lld {
|
|
namespace elf {
|
|
|
|
namespace {
|
|
|
|
// Specific ARM Thunk implementations. The naming convention is:
|
|
// Source State, TargetState, Target Requirement, ABS or PI, Range
|
|
class ARMV7ABSLongThunk final : public Thunk {
|
|
public:
|
|
ARMV7ABSLongThunk(const SymbolBody &Dest) : Thunk(Dest) {}
|
|
|
|
uint32_t size() const override { return 12; }
|
|
void writeTo(uint8_t *Buf, ThunkSection &IS) const override;
|
|
void addSymbols(ThunkSection &IS) override;
|
|
bool isCompatibleWith(uint32_t RelocType) const override;
|
|
};
|
|
|
|
class ARMV7PILongThunk final : public Thunk {
|
|
public:
|
|
ARMV7PILongThunk(const SymbolBody &Dest) : Thunk(Dest) {}
|
|
|
|
uint32_t size() const override { return 16; }
|
|
void writeTo(uint8_t *Buf, ThunkSection &IS) const override;
|
|
void addSymbols(ThunkSection &IS) override;
|
|
bool isCompatibleWith(uint32_t RelocType) const override;
|
|
};
|
|
|
|
class ThumbV7ABSLongThunk final : public Thunk {
|
|
public:
|
|
ThumbV7ABSLongThunk(const SymbolBody &Dest) : Thunk(Dest) {
|
|
alignment = 2;
|
|
}
|
|
|
|
uint32_t size() const override { return 10; }
|
|
void writeTo(uint8_t *Buf, ThunkSection &IS) const override;
|
|
void addSymbols(ThunkSection &IS) override;
|
|
bool isCompatibleWith(uint32_t RelocType) const override;
|
|
};
|
|
|
|
class ThumbV7PILongThunk final : public Thunk {
|
|
public:
|
|
ThumbV7PILongThunk(const SymbolBody &Dest) : Thunk(Dest) {
|
|
alignment = 2;
|
|
}
|
|
|
|
uint32_t size() const override { return 12; }
|
|
void writeTo(uint8_t *Buf, ThunkSection &IS) const override;
|
|
void addSymbols(ThunkSection &IS) override;
|
|
bool isCompatibleWith(uint32_t RelocType) const override;
|
|
};
|
|
|
|
// MIPS LA25 thunk
|
|
class MipsThunk final : public Thunk {
|
|
public:
|
|
MipsThunk(const SymbolBody &Dest) : Thunk(Dest) {}
|
|
|
|
uint32_t size() const override { return 16; }
|
|
void writeTo(uint8_t *Buf, ThunkSection &IS) const override;
|
|
void addSymbols(ThunkSection &IS) override;
|
|
InputSection *getTargetInputSection() const override;
|
|
};
|
|
|
|
} // end anonymous namespace
|
|
|
|
// ARM Target Thunks
|
|
static uint64_t getARMThunkDestVA(const SymbolBody &S) {
|
|
uint64_t V = S.isInPlt() ? S.getPltVA() : S.getVA();
|
|
return SignExtend64<32>(V);
|
|
}
|
|
|
|
void ARMV7ABSLongThunk::writeTo(uint8_t *Buf, ThunkSection &IS) const {
|
|
const uint8_t Data[] = {
|
|
0x00, 0xc0, 0x00, 0xe3, // movw ip,:lower16:S
|
|
0x00, 0xc0, 0x40, 0xe3, // movt ip,:upper16:S
|
|
0x1c, 0xff, 0x2f, 0xe1, // bx ip
|
|
};
|
|
uint64_t S = getARMThunkDestVA(Destination);
|
|
memcpy(Buf, Data, sizeof(Data));
|
|
Target->relocateOne(Buf, R_ARM_MOVW_ABS_NC, S);
|
|
Target->relocateOne(Buf + 4, R_ARM_MOVT_ABS, S);
|
|
}
|
|
|
|
void ARMV7ABSLongThunk::addSymbols(ThunkSection &IS) {
|
|
ThunkSym = addSyntheticLocal(
|
|
Saver.save("__ARMv7ABSLongThunk_" + Destination.getName()), STT_FUNC,
|
|
Offset, size(), &IS);
|
|
addSyntheticLocal("$a", STT_NOTYPE, Offset, 0, &IS);
|
|
}
|
|
|
|
bool ARMV7ABSLongThunk::isCompatibleWith(uint32_t RelocType) const {
|
|
// Thumb branch relocations can't use BLX
|
|
return RelocType != R_ARM_THM_JUMP19 && RelocType != R_ARM_THM_JUMP24;
|
|
}
|
|
|
|
void ThumbV7ABSLongThunk::writeTo(uint8_t *Buf, ThunkSection &IS) const {
|
|
const uint8_t Data[] = {
|
|
0x40, 0xf2, 0x00, 0x0c, // movw ip, :lower16:S
|
|
0xc0, 0xf2, 0x00, 0x0c, // movt ip, :upper16:S
|
|
0x60, 0x47, // bx ip
|
|
};
|
|
uint64_t S = getARMThunkDestVA(Destination);
|
|
memcpy(Buf, Data, sizeof(Data));
|
|
Target->relocateOne(Buf, R_ARM_THM_MOVW_ABS_NC, S);
|
|
Target->relocateOne(Buf + 4, R_ARM_THM_MOVT_ABS, S);
|
|
}
|
|
|
|
void ThumbV7ABSLongThunk::addSymbols(ThunkSection &IS) {
|
|
ThunkSym = addSyntheticLocal(
|
|
Saver.save("__Thumbv7ABSLongThunk_" + Destination.getName()), STT_FUNC,
|
|
Offset | 0x1, size(), &IS);
|
|
addSyntheticLocal("$t", STT_NOTYPE, Offset, 0, &IS);
|
|
}
|
|
|
|
bool ThumbV7ABSLongThunk::isCompatibleWith(uint32_t RelocType) const {
|
|
// ARM branch relocations can't use BLX
|
|
return RelocType != R_ARM_JUMP24 && RelocType != R_ARM_PC24 &&
|
|
RelocType != R_ARM_PLT32;
|
|
}
|
|
|
|
void ARMV7PILongThunk::writeTo(uint8_t *Buf, ThunkSection &IS) const {
|
|
const uint8_t Data[] = {
|
|
0xf0, 0xcf, 0x0f, 0xe3, // P: movw ip,:lower16:S - (P + (L1-P) +8)
|
|
0x00, 0xc0, 0x40, 0xe3, // movt ip,:upper16:S - (P + (L1-P+4) +8)
|
|
0x0f, 0xc0, 0x8c, 0xe0, // L1: add ip, ip, pc
|
|
0x1c, 0xff, 0x2f, 0xe1, // bx r12
|
|
};
|
|
uint64_t S = getARMThunkDestVA(Destination);
|
|
uint64_t P = ThunkSym->getVA();
|
|
memcpy(Buf, Data, sizeof(Data));
|
|
Target->relocateOne(Buf, R_ARM_MOVW_PREL_NC, S - P - 16);
|
|
Target->relocateOne(Buf + 4, R_ARM_MOVT_PREL, S - P - 12);
|
|
}
|
|
|
|
void ARMV7PILongThunk::addSymbols(ThunkSection &IS) {
|
|
ThunkSym = addSyntheticLocal(
|
|
Saver.save("__ARMV7PILongThunk_" + Destination.getName()), STT_FUNC,
|
|
Offset, size(), &IS);
|
|
addSyntheticLocal("$a", STT_NOTYPE, Offset, 0, &IS);
|
|
}
|
|
|
|
bool ARMV7PILongThunk::isCompatibleWith(uint32_t RelocType) const {
|
|
// Thumb branch relocations can't use BLX
|
|
return RelocType != R_ARM_THM_JUMP19 && RelocType != R_ARM_THM_JUMP24;
|
|
}
|
|
|
|
void ThumbV7PILongThunk::writeTo(uint8_t *Buf, ThunkSection &IS) const {
|
|
const uint8_t Data[] = {
|
|
0x4f, 0xf6, 0xf4, 0x7c, // P: movw ip,:lower16:S - (P + (L1-P) + 4)
|
|
0xc0, 0xf2, 0x00, 0x0c, // movt ip,:upper16:S - (P + (L1-P+4) + 4)
|
|
0xfc, 0x44, // L1: add r12, pc
|
|
0x60, 0x47, // bx r12
|
|
};
|
|
uint64_t S = getARMThunkDestVA(Destination);
|
|
uint64_t P = ThunkSym->getVA() & ~0x1;
|
|
memcpy(Buf, Data, sizeof(Data));
|
|
Target->relocateOne(Buf, R_ARM_THM_MOVW_PREL_NC, S - P - 12);
|
|
Target->relocateOne(Buf + 4, R_ARM_THM_MOVT_PREL, S - P - 8);
|
|
}
|
|
|
|
void ThumbV7PILongThunk::addSymbols(ThunkSection &IS) {
|
|
ThunkSym = addSyntheticLocal(
|
|
Saver.save("__ThumbV7PILongThunk_" + Destination.getName()), STT_FUNC,
|
|
Offset | 0x1, size(), &IS);
|
|
addSyntheticLocal("$t", STT_NOTYPE, Offset, 0, &IS);
|
|
}
|
|
|
|
bool ThumbV7PILongThunk::isCompatibleWith(uint32_t RelocType) const {
|
|
// ARM branch relocations can't use BLX
|
|
return RelocType != R_ARM_JUMP24 && RelocType != R_ARM_PC24 &&
|
|
RelocType != R_ARM_PLT32;
|
|
}
|
|
|
|
// Write MIPS LA25 thunk code to call PIC function from the non-PIC one.
|
|
void MipsThunk::writeTo(uint8_t *Buf, ThunkSection &) const {
|
|
uint64_t S = Destination.getVA();
|
|
write32(Buf, 0x3c190000, Config->Endianness); // lui $25, %hi(func)
|
|
write32(Buf + 4, 0x08000000 | (S >> 2), Config->Endianness); // j func
|
|
write32(Buf + 8, 0x27390000, Config->Endianness); // addiu $25, $25, %lo(func)
|
|
write32(Buf + 12, 0x00000000, Config->Endianness); // nop
|
|
Target->relocateOne(Buf, R_MIPS_HI16, S);
|
|
Target->relocateOne(Buf + 8, R_MIPS_LO16, S);
|
|
}
|
|
|
|
void MipsThunk::addSymbols(ThunkSection &IS) {
|
|
ThunkSym =
|
|
addSyntheticLocal(Saver.save("__LA25Thunk_" + Destination.getName()),
|
|
STT_FUNC, Offset, size(), &IS);
|
|
}
|
|
|
|
InputSection *MipsThunk::getTargetInputSection() const {
|
|
auto *DR = dyn_cast<DefinedRegular>(&Destination);
|
|
return dyn_cast<InputSection>(DR->Section);
|
|
}
|
|
|
|
Thunk::Thunk(const SymbolBody &D) : Destination(D), Offset(0) {}
|
|
|
|
Thunk::~Thunk() = default;
|
|
|
|
// Creates a thunk for Thumb-ARM interworking.
|
|
static Thunk *addThunkArm(uint32_t Reloc, SymbolBody &S) {
|
|
// ARM relocations need ARM to Thumb interworking Thunks.
|
|
// Thumb relocations need Thumb to ARM relocations.
|
|
// Use position independent Thunks if we require position independent code.
|
|
switch (Reloc) {
|
|
case R_ARM_PC24:
|
|
case R_ARM_PLT32:
|
|
case R_ARM_JUMP24:
|
|
if (Config->Pic)
|
|
return make<ARMV7PILongThunk>(S);
|
|
return make<ARMV7ABSLongThunk>(S);
|
|
case R_ARM_THM_JUMP19:
|
|
case R_ARM_THM_JUMP24:
|
|
if (Config->Pic)
|
|
return make<ThumbV7PILongThunk>(S);
|
|
return make<ThumbV7ABSLongThunk>(S);
|
|
}
|
|
fatal("unrecognized relocation type");
|
|
}
|
|
|
|
static Thunk *addThunkMips(SymbolBody &S) {
|
|
return make<MipsThunk>(S);
|
|
}
|
|
|
|
Thunk *addThunk(uint32_t RelocType, SymbolBody &S) {
|
|
if (Config->EMachine == EM_ARM)
|
|
return addThunkArm(RelocType, S);
|
|
else if (Config->EMachine == EM_MIPS)
|
|
return addThunkMips(S);
|
|
llvm_unreachable("add Thunk only supported for ARM and Mips");
|
|
return nullptr;
|
|
}
|
|
|
|
} // end namespace elf
|
|
} // end namespace lld
|