maxjhandsome
/
llvm-project
forked from OSchip/llvm-project
1
0
Fork 0
Code Issues Pull Requests Packages Releases Wiki Activity
llvm-project/lld/ELF/Target.cpp

1562 lines
52 KiB
C++
Raw Blame History

//===- Target.cpp ---------------------------------------------------------===//
//
// The LLVM Linker
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// Machine-specific things, such as applying relocations, creation of
// GOT or PLT entries, etc., are handled in this file.
//
// Refer the ELF spec for the single letter varaibles, S, A or P, used
// in this file.
//
// Some functions defined in this file has "relaxTls" as part of their names.
// They do peephole optimization for TLS variables by rewriting instructions.
// They are not part of the ABI but optional optimization, so you can skip
// them if you are not interested in how TLS variables are optimized.
// See the following paper for the details.
//
// Ulrich Drepper, ELF Handling For Thread-Local Storage
// http://www.akkadia.org/drepper/tls.pdf
//
//===----------------------------------------------------------------------===//
#include "Target.h"
#include "Error.h"
#include "InputFiles.h"
#include "OutputSections.h"
#include "Symbols.h"
#include "llvm/ADT/ArrayRef.h"
#include "llvm/Object/ELF.h"
#include "llvm/Support/Endian.h"
#include "llvm/Support/ELF.h"
using namespace llvm;
using namespace llvm::object;
using namespace llvm::support::endian;
using namespace llvm::ELF;
namespace lld {
namespace elf {
TargetInfo *Target;
static void or32le(uint8_t *P, int32_t V) { write32le(P, read32le(P) | V); }
template <unsigned N> static void checkInt(int64_t V, uint32_t Type) {
if (isInt<N>(V))
return;
StringRef S = getELFRelocationTypeName(Config->EMachine, Type);
error("relocation " + S + " out of range");
}
template <unsigned N> static void checkUInt(uint64_t V, uint32_t Type) {
if (isUInt<N>(V))
return;
StringRef S = getELFRelocationTypeName(Config->EMachine, Type);
error("relocation " + S + " out of range");
}
template <unsigned N> static void checkIntUInt(uint64_t V, uint32_t Type) {
if (isInt<N>(V) || isUInt<N>(V))
return;
StringRef S = getELFRelocationTypeName(Config->EMachine, Type);
error("relocation " + S + " out of range");
}
template <unsigned N> static void checkAlignment(uint64_t V, uint32_t Type) {
if ((V & (N - 1)) == 0)
return;
StringRef S = getELFRelocationTypeName(Config->EMachine, Type);
error("improper alignment for relocation " + S);
}
namespace {
class X86TargetInfo final : public TargetInfo {
public:
X86TargetInfo();
RelExpr getRelExpr(uint32_t Type, const SymbolBody &S) const override;
uint64_t getImplicitAddend(const uint8_t *Buf, uint32_t Type) const override;
void writeGotPltHeader(uint8_t *Buf) const override;
uint32_t getDynRel(uint32_t Type) const override;
bool isTlsLocalDynamicRel(uint32_t Type) const override;
bool isTlsGlobalDynamicRel(uint32_t Type) const override;
bool isTlsInitialExecRel(uint32_t Type) const override;
void writeGotPlt(uint8_t *Buf, uint64_t Plt) const override;
void writePltZero(uint8_t *Buf) const override;
void writePlt(uint8_t *Buf, uint64_t GotEntryAddr, uint64_t PltEntryAddr,
int32_t Index, unsigned RelOff) const override;
void relocateOne(uint8_t *Loc, uint32_t Type, uint64_t Val) const override;
void relaxTlsGdToIe(uint8_t *Loc, uint32_t Type, uint64_t Val) const override;
void relaxTlsGdToLe(uint8_t *Loc, uint32_t Type, uint64_t Val) const override;
void relaxTlsIeToLe(uint8_t *Loc, uint32_t Type, uint64_t Val) const override;
void relaxTlsLdToLe(uint8_t *Loc, uint32_t Type, uint64_t Val) const override;
};
class X86_64TargetInfo final : public TargetInfo {
public:
X86_64TargetInfo();
RelExpr getRelExpr(uint32_t Type, const SymbolBody &S) const override;
uint32_t getDynRel(uint32_t Type) const override;
bool isTlsLocalDynamicRel(uint32_t Type) const override;
bool isTlsGlobalDynamicRel(uint32_t Type) const override;
bool isTlsInitialExecRel(uint32_t Type) const override;
void writeGotPltHeader(uint8_t *Buf) const override;
void writeGotPlt(uint8_t *Buf, uint64_t Plt) const override;
void writePltZero(uint8_t *Buf) const override;
void writePlt(uint8_t *Buf, uint64_t GotEntryAddr, uint64_t PltEntryAddr,
int32_t Index, unsigned RelOff) const override;
void relocateOne(uint8_t *Loc, uint32_t Type, uint64_t Val) const override;
bool canRelaxGot(uint32_t Type, const uint8_t *Data,
uint64_t Offset) const override;
void relaxGot(uint8_t *Loc, uint64_t Val) const override;
void relaxTlsGdToIe(uint8_t *Loc, uint32_t Type, uint64_t Val) const override;
void relaxTlsGdToLe(uint8_t *Loc, uint32_t Type, uint64_t Val) const override;
void relaxTlsIeToLe(uint8_t *Loc, uint32_t Type, uint64_t Val) const override;
void relaxTlsLdToLe(uint8_t *Loc, uint32_t Type, uint64_t Val) const override;
};
class PPCTargetInfo final : public TargetInfo {
public:
PPCTargetInfo();
void relocateOne(uint8_t *Loc, uint32_t Type, uint64_t Val) const override;
RelExpr getRelExpr(uint32_t Type, const SymbolBody &S) const override;
};
class PPC64TargetInfo final : public TargetInfo {
public:
PPC64TargetInfo();
RelExpr getRelExpr(uint32_t Type, const SymbolBody &S) const override;
void writePlt(uint8_t *Buf, uint64_t GotEntryAddr, uint64_t PltEntryAddr,
int32_t Index, unsigned RelOff) const override;
void relocateOne(uint8_t *Loc, uint32_t Type, uint64_t Val) const override;
};
class AArch64TargetInfo final : public TargetInfo {
public:
AArch64TargetInfo();
RelExpr getRelExpr(uint32_t Type, const SymbolBody &S) const override;
uint32_t getDynRel(uint32_t Type) const override;
bool isTlsGlobalDynamicRel(uint32_t Type) const override;
bool isTlsInitialExecRel(uint32_t Type) const override;
void writeGotPlt(uint8_t *Buf, uint64_t Plt) const override;
void writePltZero(uint8_t *Buf) const override;
void writePlt(uint8_t *Buf, uint64_t GotEntryAddr, uint64_t PltEntryAddr,
int32_t Index, unsigned RelOff) const override;
bool usesOnlyLowPageBits(uint32_t Type) const override;
void relocateOne(uint8_t *Loc, uint32_t Type, uint64_t Val) const override;
void relaxTlsGdToLe(uint8_t *Loc, uint32_t Type, uint64_t Val) const override;
void relaxTlsIeToLe(uint8_t *Loc, uint32_t Type, uint64_t Val) const override;
};
class AMDGPUTargetInfo final : public TargetInfo {
public:
AMDGPUTargetInfo() {}
void relocateOne(uint8_t *Loc, uint32_t Type, uint64_t Val) const override;
RelExpr getRelExpr(uint32_t Type, const SymbolBody &S) const override;
};
template <class ELFT> class MipsTargetInfo final : public TargetInfo {
public:
MipsTargetInfo();
RelExpr getRelExpr(uint32_t Type, const SymbolBody &S) const override;
uint64_t getImplicitAddend(const uint8_t *Buf, uint32_t Type) const override;
uint32_t getDynRel(uint32_t Type) const override;
void writeGotPlt(uint8_t *Buf, uint64_t Plt) const override;
void writePltZero(uint8_t *Buf) const override;
void writePlt(uint8_t *Buf, uint64_t GotEntryAddr, uint64_t PltEntryAddr,
int32_t Index, unsigned RelOff) const override;
void writeThunk(uint8_t *Buf, uint64_t S) const override;
bool needsThunk(uint32_t Type, const InputFile &File,
const SymbolBody &S) const override;
void relocateOne(uint8_t *Loc, uint32_t Type, uint64_t Val) const override;
bool usesOnlyLowPageBits(uint32_t Type) const override;
};
} // anonymous namespace
TargetInfo *createTarget() {
switch (Config->EMachine) {
case EM_386:
return new X86TargetInfo();
case EM_AARCH64:
return new AArch64TargetInfo();
case EM_AMDGPU:
return new AMDGPUTargetInfo();
case EM_MIPS:
switch (Config->EKind) {
case ELF32LEKind:
return new MipsTargetInfo<ELF32LE>();
case ELF32BEKind:
return new MipsTargetInfo<ELF32BE>();
case ELF64LEKind:
return new MipsTargetInfo<ELF64LE>();
case ELF64BEKind:
return new MipsTargetInfo<ELF64BE>();
default:
fatal("unsupported MIPS target");
}
case EM_PPC:
return new PPCTargetInfo();
case EM_PPC64:
return new PPC64TargetInfo();
case EM_X86_64:
return new X86_64TargetInfo();
}
fatal("unknown target machine");
}
TargetInfo::~TargetInfo() {}
uint64_t TargetInfo::getImplicitAddend(const uint8_t *Buf,
uint32_t Type) const {
return 0;
}
uint64_t TargetInfo::getVAStart() const { return Config->Pic ? 0 : VAStart; }
bool TargetInfo::usesOnlyLowPageBits(uint32_t Type) const { return false; }
bool TargetInfo::needsThunk(uint32_t Type, const InputFile &File,
const SymbolBody &S) const {
return false;
}
bool TargetInfo::isTlsInitialExecRel(uint32_t Type) const { return false; }
bool TargetInfo::isTlsLocalDynamicRel(uint32_t Type) const { return false; }
bool TargetInfo::isTlsGlobalDynamicRel(uint32_t Type) const {
return false;
}
bool TargetInfo::canRelaxGot(uint32_t Type, const uint8_t *Data,
uint64_t Offset) const {
return false;
}
void TargetInfo::relaxGot(uint8_t *Loc, uint64_t Val) const {
llvm_unreachable("Should not have claimed to be relaxable");
}
void TargetInfo::relaxTlsGdToLe(uint8_t *Loc, uint32_t Type,
uint64_t Val) const {
llvm_unreachable("Should not have claimed to be relaxable");
}
void TargetInfo::relaxTlsGdToIe(uint8_t *Loc, uint32_t Type,
uint64_t Val) const {
llvm_unreachable("Should not have claimed to be relaxable");
}
void TargetInfo::relaxTlsIeToLe(uint8_t *Loc, uint32_t Type,
uint64_t Val) const {
llvm_unreachable("Should not have claimed to be relaxable");
}
void TargetInfo::relaxTlsLdToLe(uint8_t *Loc, uint32_t Type,
uint64_t Val) const {
llvm_unreachable("Should not have claimed to be relaxable");
}
X86TargetInfo::X86TargetInfo() {
CopyRel = R_386_COPY;
GotRel = R_386_GLOB_DAT;
PltRel = R_386_JUMP_SLOT;
IRelativeRel = R_386_IRELATIVE;
RelativeRel = R_386_RELATIVE;
TlsGotRel = R_386_TLS_TPOFF;
TlsModuleIndexRel = R_386_TLS_DTPMOD32;
TlsOffsetRel = R_386_TLS_DTPOFF32;
PltEntrySize = 16;
PltZeroSize = 16;
TlsGdToLeSkip = 2;
}
RelExpr X86TargetInfo::getRelExpr(uint32_t Type, const SymbolBody &S) const {
switch (Type) {
default:
return R_ABS;
case R_386_TLS_GD:
return R_TLSGD;
case R_386_TLS_LDM:
return R_TLSLD;
case R_386_PLT32:
return R_PLT_PC;
case R_386_PC32:
return R_PC;
case R_386_GOTPC:
return R_GOTONLY_PC;
case R_386_TLS_IE:
return R_GOT;
case R_386_GOT32:
case R_386_TLS_GOTIE:
return R_GOT_FROM_END;
case R_386_GOTOFF:
return R_GOTREL;
case R_386_TLS_LE:
return R_TLS;
case R_386_TLS_LE_32:
return R_NEG_TLS;
}
}
void X86TargetInfo::writeGotPltHeader(uint8_t *Buf) const {
write32le(Buf, Out<ELF32LE>::Dynamic->getVA());
}
void X86TargetInfo::writeGotPlt(uint8_t *Buf, uint64_t Plt) const {
// Entries in .got.plt initially points back to the corresponding
// PLT entries with a fixed offset to skip the first instruction.
write32le(Buf, Plt + 6);
}
uint32_t X86TargetInfo::getDynRel(uint32_t Type) const {
if (Type == R_386_TLS_LE)
return R_386_TLS_TPOFF;
if (Type == R_386_TLS_LE_32)
return R_386_TLS_TPOFF32;
return Type;
}
bool X86TargetInfo::isTlsGlobalDynamicRel(uint32_t Type) const {
return Type == R_386_TLS_GD;
}
bool X86TargetInfo::isTlsLocalDynamicRel(uint32_t Type) const {
return Type == R_386_TLS_LDO_32 || Type == R_386_TLS_LDM;
}
bool X86TargetInfo::isTlsInitialExecRel(uint32_t Type) const {
return Type == R_386_TLS_IE || Type == R_386_TLS_GOTIE;
}
void X86TargetInfo::writePltZero(uint8_t *Buf) const {
// Executable files and shared object files have
// separate procedure linkage tables.
if (Config->Pic) {
const uint8_t V[] = {
0xff, 0xb3, 0x04, 0x00, 0x00, 0x00, // pushl 4(%ebx)
0xff, 0xa3, 0x08, 0x00, 0x00, 0x00, // jmp *8(%ebx)
0x90, 0x90, 0x90, 0x90 // nop; nop; nop; nop
};
memcpy(Buf, V, sizeof(V));
return;
}
const uint8_t PltData[] = {
0xff, 0x35, 0x00, 0x00, 0x00, 0x00, // pushl (GOT+4)
0xff, 0x25, 0x00, 0x00, 0x00, 0x00, // jmp *(GOT+8)
0x90, 0x90, 0x90, 0x90 // nop; nop; nop; nop
};
memcpy(Buf, PltData, sizeof(PltData));
uint32_t Got = Out<ELF32LE>::GotPlt->getVA();
write32le(Buf + 2, Got + 4);
write32le(Buf + 8, Got + 8);
}
void X86TargetInfo::writePlt(uint8_t *Buf, uint64_t GotEntryAddr,
uint64_t PltEntryAddr, int32_t Index,
unsigned RelOff) const {
const uint8_t Inst[] = {
0xff, 0x00, 0x00, 0x00, 0x00, 0x00, // jmp *foo_in_GOT|*foo@GOT(%ebx)
0x68, 0x00, 0x00, 0x00, 0x00, // pushl $reloc_offset
0xe9, 0x00, 0x00, 0x00, 0x00 // jmp .PLT0@PC
};
memcpy(Buf, Inst, sizeof(Inst));
// jmp *foo@GOT(%ebx) or jmp *foo_in_GOT
Buf[1] = Config->Pic ? 0xa3 : 0x25;
uint32_t Got = Out<ELF32LE>::GotPlt->getVA();
write32le(Buf + 2, Config->Shared ? GotEntryAddr - Got : GotEntryAddr);
write32le(Buf + 7, RelOff);
write32le(Buf + 12, -Index * PltEntrySize - PltZeroSize - 16);
}
uint64_t X86TargetInfo::getImplicitAddend(const uint8_t *Buf,
uint32_t Type) const {
switch (Type) {
default:
return 0;
case R_386_32:
case R_386_GOT32:
case R_386_GOTOFF:
case R_386_GOTPC:
case R_386_PC32:
case R_386_PLT32:
return read32le(Buf);
}
}
void X86TargetInfo::relocateOne(uint8_t *Loc, uint32_t Type,
uint64_t Val) const {
checkInt<32>(Val, Type);
write32le(Loc, Val);
}
void X86TargetInfo::relaxTlsGdToLe(uint8_t *Loc, uint32_t Type,
uint64_t Val) const {
// Convert
// leal x@tlsgd(, %ebx, 1),
// call __tls_get_addr@plt
// to
// movl %gs:0,%eax
// subl $x@ntpoff,%eax
const uint8_t Inst[] = {
0x65, 0xa1, 0x00, 0x00, 0x00, 0x00, // movl %gs:0, %eax
0x81, 0xe8, 0x00, 0x00, 0x00, 0x00 // subl 0(%ebx), %eax
};
memcpy(Loc - 3, Inst, sizeof(Inst));
relocateOne(Loc + 5, R_386_32, Val);
}
void X86TargetInfo::relaxTlsGdToIe(uint8_t *Loc, uint32_t Type,
uint64_t Val) const {
// Convert
// leal x@tlsgd(, %ebx, 1),
// call __tls_get_addr@plt
// to
// movl %gs:0, %eax
// addl x@gotntpoff(%ebx), %eax
const uint8_t Inst[] = {
0x65, 0xa1, 0x00, 0x00, 0x00, 0x00, // movl %gs:0, %eax
0x03, 0x83, 0x00, 0x00, 0x00, 0x00 // addl 0(%ebx), %eax
};
memcpy(Loc - 3, Inst, sizeof(Inst));
relocateOne(Loc + 5, R_386_32, Val);
}
// In some conditions, relocations can be optimized to avoid using GOT.
// This function does that for Initial Exec to Local Exec case.
void X86TargetInfo::relaxTlsIeToLe(uint8_t *Loc, uint32_t Type,
uint64_t Val) const {
// Ulrich's document section 6.2 says that @gotntpoff can
// be used with MOVL or ADDL instructions.
// @indntpoff is similar to @gotntpoff, but for use in
// position dependent code.
uint8_t *Inst = Loc - 2;
uint8_t *Op = Loc - 1;
uint8_t Reg = (Loc[-1] >> 3) & 7;
bool IsMov = *Inst == 0x8b;
if (Type == R_386_TLS_IE) {
// For R_386_TLS_IE relocation we perform the next transformations:
// MOVL foo@INDNTPOFF,%EAX is transformed to MOVL $foo,%EAX
// MOVL foo@INDNTPOFF,%REG is transformed to MOVL $foo,%REG
// ADDL foo@INDNTPOFF,%REG is transformed to ADDL $foo,%REG
// First one is special because when EAX is used the sequence is 5 bytes
// long, otherwise it is 6 bytes.
if (*Op == 0xa1) {
*Op = 0xb8;
} else {
*Inst = IsMov ? 0xc7 : 0x81;
*Op = 0xc0 | ((*Op >> 3) & 7);
}
} else {
// R_386_TLS_GOTIE relocation can be optimized to
// R_386_TLS_LE so that it does not use GOT.
// "MOVL foo@GOTTPOFF(%RIP), %REG" is transformed to "MOVL $foo, %REG".
// "ADDL foo@GOTNTPOFF(%RIP), %REG" is transformed to "LEAL foo(%REG), %REG"
// Note: gold converts to ADDL instead of LEAL.
*Inst = IsMov ? 0xc7 : 0x8d;
if (IsMov)
*Op = 0xc0 | ((*Op >> 3) & 7);
else
*Op = 0x80 | Reg | (Reg << 3);
}
relocateOne(Loc, R_386_TLS_LE, Val);
}
void X86TargetInfo::relaxTlsLdToLe(uint8_t *Loc, uint32_t Type,
uint64_t Val) const {
if (Type == R_386_TLS_LDO_32) {
relocateOne(Loc, R_386_TLS_LE, Val);
return;
}
// Convert
// leal foo(%reg),%eax
// call ___tls_get_addr
// to
// movl %gs:0,%eax
// nop
// leal 0(%esi,1),%esi
const uint8_t Inst[] = {
0x65, 0xa1, 0x00, 0x00, 0x00, 0x00, // movl %gs:0,%eax
0x90, // nop
0x8d, 0x74, 0x26, 0x00 // leal 0(%esi,1),%esi
};
memcpy(Loc - 2, Inst, sizeof(Inst));
}
X86_64TargetInfo::X86_64TargetInfo() {
CopyRel = R_X86_64_COPY;
GotRel = R_X86_64_GLOB_DAT;
PltRel = R_X86_64_JUMP_SLOT;
RelativeRel = R_X86_64_RELATIVE;
IRelativeRel = R_X86_64_IRELATIVE;
TlsGotRel = R_X86_64_TPOFF64;
TlsModuleIndexRel = R_X86_64_DTPMOD64;
TlsOffsetRel = R_X86_64_DTPOFF64;
PltEntrySize = 16;
PltZeroSize = 16;
TlsGdToLeSkip = 2;
}
RelExpr X86_64TargetInfo::getRelExpr(uint32_t Type, const SymbolBody &S) const {
switch (Type) {
default:
return R_ABS;
case R_X86_64_TPOFF32:
return R_TLS;
case R_X86_64_TLSLD:
return R_TLSLD_PC;
case R_X86_64_TLSGD:
return R_TLSGD_PC;
case R_X86_64_SIZE32:
case R_X86_64_SIZE64:
return R_SIZE;
case R_X86_64_PLT32:
return R_PLT_PC;
case R_X86_64_PC32:
case R_X86_64_PC64:
return R_PC;
case R_X86_64_GOT32:
return R_GOT_FROM_END;
case R_X86_64_GOTPCREL:
case R_X86_64_GOTPCRELX:
case R_X86_64_REX_GOTPCRELX:
case R_X86_64_GOTTPOFF:
return R_GOT_PC;
}
}
void X86_64TargetInfo::writeGotPltHeader(uint8_t *Buf) const {
// The first entry holds the value of _DYNAMIC. It is not clear why that is
// required, but it is documented in the psabi and the glibc dynamic linker
// seems to use it (note that this is relevant for linking ld.so, not any
// other program).
write64le(Buf, Out<ELF64LE>::Dynamic->getVA());
}
void X86_64TargetInfo::writeGotPlt(uint8_t *Buf, uint64_t Plt) const {
// See comments in X86TargetInfo::writeGotPlt.
write32le(Buf, Plt + 6);
}
void X86_64TargetInfo::writePltZero(uint8_t *Buf) const {
const uint8_t PltData[] = {
0xff, 0x35, 0x00, 0x00, 0x00, 0x00, // pushq GOT+8(%rip)
0xff, 0x25, 0x00, 0x00, 0x00, 0x00, // jmp *GOT+16(%rip)
0x0f, 0x1f, 0x40, 0x00 // nopl 0x0(rax)
};
memcpy(Buf, PltData, sizeof(PltData));
uint64_t Got = Out<ELF64LE>::GotPlt->getVA();
uint64_t Plt = Out<ELF64LE>::Plt->getVA();
write32le(Buf + 2, Got - Plt + 2); // GOT+8
write32le(Buf + 8, Got - Plt + 4); // GOT+16
}
void X86_64TargetInfo::writePlt(uint8_t *Buf, uint64_t GotEntryAddr,
uint64_t PltEntryAddr, int32_t Index,
unsigned RelOff) const {
const uint8_t Inst[] = {
0xff, 0x25, 0x00, 0x00, 0x00, 0x00, // jmpq *got(%rip)
0x68, 0x00, 0x00, 0x00, 0x00, // pushq <relocation index>
0xe9, 0x00, 0x00, 0x00, 0x00 // jmpq plt[0]
};
memcpy(Buf, Inst, sizeof(Inst));
write32le(Buf + 2, GotEntryAddr - PltEntryAddr - 6);
write32le(Buf + 7, Index);
write32le(Buf + 12, -Index * PltEntrySize - PltZeroSize - 16);
}
uint32_t X86_64TargetInfo::getDynRel(uint32_t Type) const {
if (Type == R_X86_64_PC32 || Type == R_X86_64_32)
if (Config->Shared)
error(getELFRelocationTypeName(EM_X86_64, Type) +
" cannot be a dynamic relocation");
return Type;
}
bool X86_64TargetInfo::isTlsInitialExecRel(uint32_t Type) const {
return Type == R_X86_64_GOTTPOFF;
}
bool X86_64TargetInfo::isTlsGlobalDynamicRel(uint32_t Type) const {
return Type == R_X86_64_TLSGD;
}
bool X86_64TargetInfo::isTlsLocalDynamicRel(uint32_t Type) const {
return Type == R_X86_64_DTPOFF32 || Type == R_X86_64_DTPOFF64 ||
Type == R_X86_64_TLSLD;
}
void X86_64TargetInfo::relaxTlsGdToLe(uint8_t *Loc, uint32_t Type,
uint64_t Val) const {
// Convert
// .byte 0x66
// leaq x@tlsgd(%rip), %rdi
// .word 0x6666
// rex64
// call __tls_get_addr@plt
// to
// mov %fs:0x0,%rax
// lea x@tpoff,%rax
const uint8_t Inst[] = {
0x64, 0x48, 0x8b, 0x04, 0x25, 0x00, 0x00, 0x00, 0x00, // mov %fs:0x0,%rax
0x48, 0x8d, 0x80, 0x00, 0x00, 0x00, 0x00 // lea x@tpoff,%rax
};
memcpy(Loc - 4, Inst, sizeof(Inst));
// The original code used a pc relative relocation and so we have to
// compensate for the -4 in had in the addend.
relocateOne(Loc + 8, R_X86_64_TPOFF32, Val + 4);
}
void X86_64TargetInfo::relaxTlsGdToIe(uint8_t *Loc, uint32_t Type,
uint64_t Val) const {
// Convert
// .byte 0x66
// leaq x@tlsgd(%rip), %rdi
// .word 0x6666
// rex64
// call __tls_get_addr@plt
// to
// mov %fs:0x0,%rax
// addq x@tpoff,%rax
const uint8_t Inst[] = {
0x64, 0x48, 0x8b, 0x04, 0x25, 0x00, 0x00, 0x00, 0x00, // mov %fs:0x0,%rax
0x48, 0x03, 0x05, 0x00, 0x00, 0x00, 0x00 // addq x@tpoff,%rax
};
memcpy(Loc - 4, Inst, sizeof(Inst));
// Both code sequences are PC relatives, but since we are moving the constant
// forward by 8 bytes we have to subtract the value by 8.
relocateOne(Loc + 8, R_X86_64_PC32, Val - 8);
}
// In some conditions, R_X86_64_GOTTPOFF relocation can be optimized to
// R_X86_64_TPOFF32 so that it does not use GOT.
void X86_64TargetInfo::relaxTlsIeToLe(uint8_t *Loc, uint32_t Type,
uint64_t Val) const {
// Ulrich's document section 6.5 says that @gottpoff(%rip) must be
// used in MOVQ or ADDQ instructions only.
// "MOVQ foo@GOTTPOFF(%RIP), %REG" is transformed to "MOVQ $foo, %REG".
// "ADDQ foo@GOTTPOFF(%RIP), %REG" is transformed to "LEAQ foo(%REG), %REG"
// (if the register is not RSP/R12) or "ADDQ $foo, %RSP".
// Opcodes info can be found at http://ref.x86asm.net/coder64.html#x48.
uint8_t *Prefix = Loc - 3;
uint8_t *Inst = Loc - 2;
uint8_t *RegSlot = Loc - 1;
uint8_t Reg = Loc[-1] >> 3;
bool IsMov = *Inst == 0x8b;
bool RspAdd = !IsMov && Reg == 4;
// r12 and rsp registers requires special handling.
// Problem is that for other registers, for example leaq 0xXXXXXXXX(%r11),%r11
// result out is 7 bytes: 4d 8d 9b XX XX XX XX,
// but leaq 0xXXXXXXXX(%r12),%r12 is 8 bytes: 4d 8d a4 24 XX XX XX XX.
// The same true for rsp. So we convert to addq for them, saving 1 byte that
// we dont have.
if (RspAdd)
*Inst = 0x81;
else
*Inst = IsMov ? 0xc7 : 0x8d;
if (*Prefix == 0x4c)
*Prefix = (IsMov || RspAdd) ? 0x49 : 0x4d;
*RegSlot = (IsMov || RspAdd) ? (0xc0 | Reg) : (0x80 | Reg | (Reg << 3));
// The original code used a pc relative relocation and so we have to
// compensate for the -4 in had in the addend.
relocateOne(Loc, R_X86_64_TPOFF32, Val + 4);
}
void X86_64TargetInfo::relaxTlsLdToLe(uint8_t *Loc, uint32_t Type,
uint64_t Val) const {
// Convert
// leaq bar@tlsld(%rip), %rdi
// callq __tls_get_addr@PLT
// leaq bar@dtpoff(%rax), %rcx
// to
// .word 0x6666
// .byte 0x66
// mov %fs:0,%rax
// leaq bar@tpoff(%rax), %rcx
if (Type == R_X86_64_DTPOFF64) {
write64le(Loc, Val);
return;
}
if (Type == R_X86_64_DTPOFF32) {
relocateOne(Loc, R_X86_64_TPOFF32, Val);
return;
}
const uint8_t Inst[] = {
0x66, 0x66, // .word 0x6666
0x66, // .byte 0x66
0x64, 0x48, 0x8b, 0x04, 0x25, 0x00, 0x00, 0x00, 0x00 // mov %fs:0,%rax
};
memcpy(Loc - 3, Inst, sizeof(Inst));
}
void X86_64TargetInfo::relocateOne(uint8_t *Loc, uint32_t Type,
uint64_t Val) const {
switch (Type) {
case R_X86_64_32:
checkUInt<32>(Val, Type);
write32le(Loc, Val);
break;
case R_X86_64_32S:
case R_X86_64_TPOFF32:
case R_X86_64_GOT32:
case R_X86_64_GOTPCREL:
case R_X86_64_GOTPCRELX:
case R_X86_64_REX_GOTPCRELX:
case R_X86_64_PC32:
case R_X86_64_GOTTPOFF:
case R_X86_64_PLT32:
case R_X86_64_TLSGD:
case R_X86_64_TLSLD:
case R_X86_64_DTPOFF32:
case R_X86_64_SIZE32:
checkInt<32>(Val, Type);
write32le(Loc, Val);
break;
case R_X86_64_64:
case R_X86_64_DTPOFF64:
case R_X86_64_SIZE64:
case R_X86_64_PC64:
write64le(Loc, Val);
break;
default:
fatal("unrecognized reloc " + Twine(Type));
}
}
bool X86_64TargetInfo::canRelaxGot(uint32_t Type, const uint8_t *Data,
uint64_t Offset) const {
if (Type != R_X86_64_GOTPCRELX && Type != R_X86_64_REX_GOTPCRELX)
return false;
// Converting mov foo@GOTPCREL(%rip), %reg to lea foo(%rip), %reg
// is the only supported relaxation for now.
return (Offset >= 2 && Data[Offset - 2] == 0x8b);
}
void X86_64TargetInfo::relaxGot(uint8_t *Loc, uint64_t Val) const {
Loc[-2] = 0x8d;
relocateOne(Loc, R_X86_64_PC32, Val);
}
// Relocation masks following the #lo(value), #hi(value), #ha(value),
// #higher(value), #highera(value), #highest(value), and #highesta(value)
// macros defined in section 4.5.1. Relocation Types of the PPC-elf64abi
// document.
static uint16_t applyPPCLo(uint64_t V) { return V; }
static uint16_t applyPPCHi(uint64_t V) { return V >> 16; }
static uint16_t applyPPCHa(uint64_t V) { return (V + 0x8000) >> 16; }
static uint16_t applyPPCHigher(uint64_t V) { return V >> 32; }
static uint16_t applyPPCHighera(uint64_t V) { return (V + 0x8000) >> 32; }
static uint16_t applyPPCHighest(uint64_t V) { return V >> 48; }
static uint16_t applyPPCHighesta(uint64_t V) { return (V + 0x8000) >> 48; }
PPCTargetInfo::PPCTargetInfo() {}
void PPCTargetInfo::relocateOne(uint8_t *Loc, uint32_t Type,
uint64_t Val) const {
switch (Type) {
case R_PPC_ADDR16_HA:
write16be(Loc, applyPPCHa(Val));
break;
case R_PPC_ADDR16_LO:
write16be(Loc, applyPPCLo(Val));
break;
default:
fatal("unrecognized reloc " + Twine(Type));
}
}
RelExpr PPCTargetInfo::getRelExpr(uint32_t Type, const SymbolBody &S) const {
return R_ABS;
}
PPC64TargetInfo::PPC64TargetInfo() {
PltRel = GotRel = R_PPC64_GLOB_DAT;
RelativeRel = R_PPC64_RELATIVE;
PltEntrySize = 32;
// We need 64K pages (at least under glibc/Linux, the loader won't
// set different permissions on a finer granularity than that).
PageSize = 65536;
// The PPC64 ELF ABI v1 spec, says:
//
// It is normally desirable to put segments with different characteristics
// in separate 256 Mbyte portions of the address space, to give the
// operating system full paging flexibility in the 64-bit address space.
//
// And because the lowest non-zero 256M boundary is 0x10000000, PPC64 linkers
// use 0x10000000 as the starting address.
VAStart = 0x10000000;
}
static uint64_t PPC64TocOffset = 0x8000;
uint64_t getPPC64TocBase() {
// The TOC consists of sections .got, .toc, .tocbss, .plt in that order. The
// TOC starts where the first of these sections starts. We always create a
// .got when we see a relocation that uses it, so for us the start is always
// the .got.
uint64_t TocVA = Out<ELF64BE>::Got->getVA();
// Per the ppc64-elf-linux ABI, The TOC base is TOC value plus 0x8000
// thus permitting a full 64 Kbytes segment. Note that the glibc startup
// code (crt1.o) assumes that you can get from the TOC base to the
// start of the .toc section with only a single (signed) 16-bit relocation.
return TocVA + PPC64TocOffset;
}
RelExpr PPC64TargetInfo::getRelExpr(uint32_t Type, const SymbolBody &S) const {
switch (Type) {
default:
return R_ABS;
case R_PPC64_TOC16:
case R_PPC64_TOC16_DS:
case R_PPC64_TOC16_HA:
case R_PPC64_TOC16_HI:
case R_PPC64_TOC16_LO:
case R_PPC64_TOC16_LO_DS:
return R_GOTREL;
case R_PPC64_TOC:
return R_PPC_TOC;
case R_PPC64_REL24:
return R_PPC_PLT_OPD;
}
}
void PPC64TargetInfo::writePlt(uint8_t *Buf, uint64_t GotEntryAddr,
uint64_t PltEntryAddr, int32_t Index,
unsigned RelOff) const {
uint64_t Off = GotEntryAddr - getPPC64TocBase();
// FIXME: What we should do, in theory, is get the offset of the function
// descriptor in the .opd section, and use that as the offset from %r2 (the
// TOC-base pointer). Instead, we have the GOT-entry offset, and that will
// be a pointer to the function descriptor in the .opd section. Using
// this scheme is simpler, but requires an extra indirection per PLT dispatch.
write32be(Buf, 0xf8410028); // std %r2, 40(%r1)
write32be(Buf + 4, 0x3d620000 | applyPPCHa(Off)); // addis %r11, %r2, X@ha
write32be(Buf + 8, 0xe98b0000 | applyPPCLo(Off)); // ld %r12, X@l(%r11)
write32be(Buf + 12, 0xe96c0000); // ld %r11,0(%r12)
write32be(Buf + 16, 0x7d6903a6); // mtctr %r11
write32be(Buf + 20, 0xe84c0008); // ld %r2,8(%r12)
write32be(Buf + 24, 0xe96c0010); // ld %r11,16(%r12)
write32be(Buf + 28, 0x4e800420); // bctr
}
void PPC64TargetInfo::relocateOne(uint8_t *Loc, uint32_t Type,
uint64_t Val) const {
uint64_t TO = PPC64TocOffset;
// For a TOC-relative relocation, proceed in terms of the corresponding
// ADDR16 relocation type.
switch (Type) {
case R_PPC64_TOC16: Type = R_PPC64_ADDR16; Val -= TO; break;
case R_PPC64_TOC16_DS: Type = R_PPC64_ADDR16_DS; Val -= TO; break;
case R_PPC64_TOC16_HA: Type = R_PPC64_ADDR16_HA; Val -= TO; break;
case R_PPC64_TOC16_HI: Type = R_PPC64_ADDR16_HI; Val -= TO; break;
case R_PPC64_TOC16_LO: Type = R_PPC64_ADDR16_LO; Val -= TO; break;
case R_PPC64_TOC16_LO_DS: Type = R_PPC64_ADDR16_LO_DS; Val -= TO; break;
default: break;
}
switch (Type) {
case R_PPC64_ADDR14: {
checkAlignment<4>(Val, Type);
// Preserve the AA/LK bits in the branch instruction
uint8_t AALK = Loc[3];
write16be(Loc + 2, (AALK & 3) | (Val & 0xfffc));
break;
}
case R_PPC64_ADDR16:
checkInt<16>(Val, Type);
write16be(Loc, Val);
break;
case R_PPC64_ADDR16_DS:
checkInt<16>(Val, Type);
write16be(Loc, (read16be(Loc) & 3) | (Val & ~3));
break;
case R_PPC64_ADDR16_HA:
write16be(Loc, applyPPCHa(Val));
break;
case R_PPC64_ADDR16_HI:
write16be(Loc, applyPPCHi(Val));
break;
case R_PPC64_ADDR16_HIGHER:
write16be(Loc, applyPPCHigher(Val));
break;
case R_PPC64_ADDR16_HIGHERA:
write16be(Loc, applyPPCHighera(Val));
break;
case R_PPC64_ADDR16_HIGHEST:
write16be(Loc, applyPPCHighest(Val));
break;
case R_PPC64_ADDR16_HIGHESTA:
write16be(Loc, applyPPCHighesta(Val));
break;
case R_PPC64_ADDR16_LO:
write16be(Loc, applyPPCLo(Val));
break;
case R_PPC64_ADDR16_LO_DS:
write16be(Loc, (read16be(Loc) & 3) | (applyPPCLo(Val) & ~3));
break;
case R_PPC64_ADDR32:
checkInt<32>(Val, Type);
write32be(Loc, Val);
break;
case R_PPC64_ADDR64:
write64be(Loc, Val);
break;
case R_PPC64_REL16_HA:
write16be(Loc, applyPPCHa(Val));
break;
case R_PPC64_REL16_HI:
write16be(Loc, applyPPCHi(Val));
break;
case R_PPC64_REL16_LO:
write16be(Loc, applyPPCLo(Val));
break;
case R_PPC64_REL24: {
uint32_t Mask = 0x03FFFFFC;
checkInt<24>(Val, Type);
write32be(Loc, (read32be(Loc) & ~Mask) | (Val & Mask));
break;
}
case R_PPC64_REL32:
checkInt<32>(Val, Type);
write32be(Loc, Val);
break;
case R_PPC64_REL64:
write64be(Loc, Val);
break;
case R_PPC64_TOC:
write64be(Loc, Val);
break;
default:
fatal("unrecognized reloc " + Twine(Type));
}
}
AArch64TargetInfo::AArch64TargetInfo() {
CopyRel = R_AARCH64_COPY;
RelativeRel = R_AARCH64_RELATIVE;
IRelativeRel = R_AARCH64_IRELATIVE;
GotRel = R_AARCH64_GLOB_DAT;
PltRel = R_AARCH64_JUMP_SLOT;
TlsGotRel = R_AARCH64_TLS_TPREL64;
TlsModuleIndexRel = R_AARCH64_TLS_DTPMOD64;
TlsOffsetRel = R_AARCH64_TLS_DTPREL64;
PltEntrySize = 16;
PltZeroSize = 32;
// It doesn't seem to be documented anywhere, but tls on aarch64 uses variant
// 1 of the tls structures and the tcb size is 16.
TcbSize = 16;
}
RelExpr AArch64TargetInfo::getRelExpr(uint32_t Type,
const SymbolBody &S) const {
switch (Type) {
default:
return R_ABS;
case R_AARCH64_TLSLE_ADD_TPREL_HI12:
case R_AARCH64_TLSLE_ADD_TPREL_LO12_NC:
return R_TLS;
case R_AARCH64_CALL26:
case R_AARCH64_CONDBR19:
case R_AARCH64_JUMP26:
case R_AARCH64_TSTBR14:
return R_PLT_PC;
case R_AARCH64_PREL16:
case R_AARCH64_PREL32:
case R_AARCH64_PREL64:
case R_AARCH64_ADR_PREL_LO21:
return R_PC;
case R_AARCH64_ADR_PREL_PG_HI21:
return R_PAGE_PC;
case R_AARCH64_LD64_GOT_LO12_NC:
case R_AARCH64_TLSIE_LD64_GOTTPREL_LO12_NC:
return R_GOT;
case R_AARCH64_ADR_GOT_PAGE:
case R_AARCH64_TLSIE_ADR_GOTTPREL_PAGE21:
return R_GOT_PAGE_PC;
}
}
bool AArch64TargetInfo::usesOnlyLowPageBits(uint32_t Type) const {
switch (Type) {
default:
return false;
case R_AARCH64_ADD_ABS_LO12_NC:
case R_AARCH64_LDST8_ABS_LO12_NC:
case R_AARCH64_LDST16_ABS_LO12_NC:
case R_AARCH64_LDST32_ABS_LO12_NC:
case R_AARCH64_LDST64_ABS_LO12_NC:
case R_AARCH64_LDST128_ABS_LO12_NC:
case R_AARCH64_LD64_GOT_LO12_NC:
case R_AARCH64_TLSIE_LD64_GOTTPREL_LO12_NC:
return true;
}
}
bool AArch64TargetInfo::isTlsGlobalDynamicRel(uint32_t Type) const {
return Type == R_AARCH64_TLSDESC_ADR_PAGE21 ||
Type == R_AARCH64_TLSDESC_LD64_LO12_NC ||
Type == R_AARCH64_TLSDESC_ADD_LO12_NC ||
Type == R_AARCH64_TLSDESC_CALL;
}
bool AArch64TargetInfo::isTlsInitialExecRel(uint32_t Type) const {
return Type == R_AARCH64_TLSIE_ADR_GOTTPREL_PAGE21 ||
Type == R_AARCH64_TLSIE_LD64_GOTTPREL_LO12_NC;
}
uint32_t AArch64TargetInfo::getDynRel(uint32_t Type) const {
if (Type == R_AARCH64_ABS32 || Type == R_AARCH64_ABS64)
return Type;
StringRef S = getELFRelocationTypeName(EM_AARCH64, Type);
error("relocation " + S + " cannot be used when making a shared object; "
"recompile with -fPIC.");
// Keep it going with a dummy value so that we can find more reloc errors.
return R_AARCH64_ABS32;
}
void AArch64TargetInfo::writeGotPlt(uint8_t *Buf, uint64_t Plt) const {
write64le(Buf, Out<ELF64LE>::Plt->getVA());
}
static uint64_t getAArch64Page(uint64_t Expr) {
return Expr & (~static_cast<uint64_t>(0xFFF));
}
void AArch64TargetInfo::writePltZero(uint8_t *Buf) const {
const uint8_t PltData[] = {
0xf0, 0x7b, 0xbf, 0xa9, // stp x16, x30, [sp,#-16]!
0x10, 0x00, 0x00, 0x90, // adrp x16, Page(&(.plt.got[2]))
0x11, 0x02, 0x40, 0xf9, // ldr x17, [x16, Offset(&(.plt.got[2]))]
0x10, 0x02, 0x00, 0x91, // add x16, x16, Offset(&(.plt.got[2]))
0x20, 0x02, 0x1f, 0xd6, // br x17
0x1f, 0x20, 0x03, 0xd5, // nop
0x1f, 0x20, 0x03, 0xd5, // nop
0x1f, 0x20, 0x03, 0xd5 // nop
};
memcpy(Buf, PltData, sizeof(PltData));
uint64_t Got = Out<ELF64LE>::GotPlt->getVA();
uint64_t Plt = Out<ELF64LE>::Plt->getVA();
relocateOne(Buf + 4, R_AARCH64_ADR_PREL_PG_HI21,
getAArch64Page(Got + 16) - getAArch64Page(Plt + 4));
relocateOne(Buf + 8, R_AARCH64_LDST64_ABS_LO12_NC, Got + 16);
relocateOne(Buf + 12, R_AARCH64_ADD_ABS_LO12_NC, Got + 16);
}
void AArch64TargetInfo::writePlt(uint8_t *Buf, uint64_t GotEntryAddr,
uint64_t PltEntryAddr, int32_t Index,
unsigned RelOff) const {
const uint8_t Inst[] = {
0x10, 0x00, 0x00, 0x90, // adrp x16, Page(&(.plt.got[n]))
0x11, 0x02, 0x40, 0xf9, // ldr x17, [x16, Offset(&(.plt.got[n]))]
0x10, 0x02, 0x00, 0x91, // add x16, x16, Offset(&(.plt.got[n]))
0x20, 0x02, 0x1f, 0xd6 // br x17
};
memcpy(Buf, Inst, sizeof(Inst));
relocateOne(Buf, R_AARCH64_ADR_PREL_PG_HI21,
getAArch64Page(GotEntryAddr) - getAArch64Page(PltEntryAddr));
relocateOne(Buf + 4, R_AARCH64_LDST64_ABS_LO12_NC, GotEntryAddr);
relocateOne(Buf + 8, R_AARCH64_ADD_ABS_LO12_NC, GotEntryAddr);
}
static void updateAArch64Addr(uint8_t *L, uint64_t Imm) {
uint32_t ImmLo = (Imm & 0x3) << 29;
uint32_t ImmHi = ((Imm & 0x1FFFFC) >> 2) << 5;
uint64_t Mask = (0x3 << 29) | (0x7FFFF << 5);
write32le(L, (read32le(L) & ~Mask) | ImmLo | ImmHi);
}
static inline void updateAArch64Add(uint8_t *L, uint64_t Imm) {
or32le(L, (Imm & 0xFFF) << 10);
}
void AArch64TargetInfo::relocateOne(uint8_t *Loc, uint32_t Type,
uint64_t Val) const {
switch (Type) {
case R_AARCH64_ABS16:
case R_AARCH64_PREL16:
checkIntUInt<16>(Val, Type);
write16le(Loc, Val);
break;
case R_AARCH64_ABS32:
case R_AARCH64_PREL32:
checkIntUInt<32>(Val, Type);
write32le(Loc, Val);
break;
case R_AARCH64_ABS64:
case R_AARCH64_PREL64:
write64le(Loc, Val);
break;
case R_AARCH64_ADD_ABS_LO12_NC:
// This relocation stores 12 bits and there's no instruction
// to do it. Instead, we do a 32 bits store of the value
// of r_addend bitwise-or'ed Loc. This assumes that the addend
// bits in Loc are zero.
or32le(Loc, (Val & 0xFFF) << 10);
break;
case R_AARCH64_ADR_GOT_PAGE:
case R_AARCH64_ADR_PREL_PG_HI21:
case R_AARCH64_TLSIE_ADR_GOTTPREL_PAGE21:
checkInt<33>(Val, Type);
updateAArch64Addr(Loc, (Val >> 12) & 0x1FFFFF); // X[32:12]
break;
case R_AARCH64_ADR_PREL_LO21:
checkInt<21>(Val, Type);
updateAArch64Addr(Loc, Val & 0x1FFFFF);
break;
case R_AARCH64_CALL26:
case R_AARCH64_JUMP26:
checkInt<28>(Val, Type);
or32le(Loc, (Val & 0x0FFFFFFC) >> 2);
break;
case R_AARCH64_CONDBR19:
checkInt<21>(Val, Type);
or32le(Loc, (Val & 0x1FFFFC) << 3);
break;
case R_AARCH64_LD64_GOT_LO12_NC:
case R_AARCH64_TLSIE_LD64_GOTTPREL_LO12_NC:
checkAlignment<8>(Val, Type);
or32le(Loc, (Val & 0xFF8) << 7);
break;
case R_AARCH64_LDST128_ABS_LO12_NC:
or32le(Loc, (Val & 0x0FF8) << 6);
break;
case R_AARCH64_LDST16_ABS_LO12_NC:
or32le(Loc, (Val & 0x0FFC) << 9);
break;
case R_AARCH64_LDST8_ABS_LO12_NC:
or32le(Loc, (Val & 0xFFF) << 10);
break;
case R_AARCH64_LDST32_ABS_LO12_NC:
or32le(Loc, (Val & 0xFFC) << 8);
break;
case R_AARCH64_LDST64_ABS_LO12_NC:
or32le(Loc, (Val & 0xFF8) << 7);
break;
case R_AARCH64_TSTBR14:
checkInt<16>(Val, Type);
or32le(Loc, (Val & 0xFFFC) << 3);
break;
case R_AARCH64_TLSLE_ADD_TPREL_HI12:
checkInt<24>(Val, Type);
updateAArch64Add(Loc, (Val & 0xFFF000) >> 12);
break;
case R_AARCH64_TLSLE_ADD_TPREL_LO12_NC:
updateAArch64Add(Loc, Val & 0xFFF);
break;
default:
fatal("unrecognized reloc " + Twine(Type));
}
}
void AArch64TargetInfo::relaxTlsGdToLe(uint8_t *Loc, uint32_t Type,
uint64_t Val) const {
// TLSDESC Global-Dynamic relocation are in the form:
// adrp x0, :tlsdesc:v [R_AARCH64_TLSDESC_ADR_PAGE21]
// ldr x1, [x0, #:tlsdesc_lo12:v [R_AARCH64_TLSDESC_LD64_LO12_NC]
// add x0, x0, :tlsdesc_los:v [_AARCH64_TLSDESC_ADD_LO12_NC]
// .tlsdesccall [R_AARCH64_TLSDESC_CALL]
// And it can optimized to:
// movz x0, #0x0, lsl #16
// movk x0, #0x10
// nop
// nop
checkUInt<32>(Val, Type);
uint32_t NewInst;
switch (Type) {
case R_AARCH64_TLSDESC_ADD_LO12_NC:
case R_AARCH64_TLSDESC_CALL:
// nop
NewInst = 0xd503201f;
break;
case R_AARCH64_TLSDESC_ADR_PAGE21:
// movz
NewInst = 0xd2a00000 | (((Val >> 16) & 0xffff) << 5);
break;
case R_AARCH64_TLSDESC_LD64_LO12_NC:
// movk
NewInst = 0xf2800000 | ((Val & 0xffff) << 5);
break;
default:
llvm_unreachable("unsupported Relocation for TLS GD to LE relax");
}
write32le(Loc, NewInst);
}
void AArch64TargetInfo::relaxTlsIeToLe(uint8_t *Loc, uint32_t Type,
uint64_t Val) const {
checkUInt<32>(Val, Type);
uint32_t Inst = read32le(Loc);
uint32_t NewInst;
if (Type == R_AARCH64_TLSIE_ADR_GOTTPREL_PAGE21) {
// Generate movz.
unsigned RegNo = (Inst & 0x1f);
NewInst = (0xd2a00000 | RegNo) | (((Val >> 16) & 0xffff) << 5);
} else if (Type == R_AARCH64_TLSIE_LD64_GOTTPREL_LO12_NC) {
// Generate movk
unsigned RegNo = (Inst & 0x1f);
NewInst = (0xf2800000 | RegNo) | ((Val & 0xffff) << 5);
} else {
llvm_unreachable("invalid Relocation for TLS IE to LE Relax");
}
write32le(Loc, NewInst);
}
// Implementing relocations for AMDGPU is low priority since most
// programs don't use relocations now. Thus, this function is not
// actually called (relocateOne is called for each relocation).
// That's why the AMDGPU port works without implementing this function.
void AMDGPUTargetInfo::relocateOne(uint8_t *Loc, uint32_t Type,
uint64_t Val) const {
llvm_unreachable("not implemented");
}
RelExpr AMDGPUTargetInfo::getRelExpr(uint32_t Type, const SymbolBody &S) const {
llvm_unreachable("not implemented");
}
template <class ELFT> MipsTargetInfo<ELFT>::MipsTargetInfo() {
GotPltHeaderEntriesNum = 2;
PageSize = 65536;
PltEntrySize = 16;
PltZeroSize = 32;
ThunkSize = 16;
CopyRel = R_MIPS_COPY;
PltRel = R_MIPS_JUMP_SLOT;
if (ELFT::Is64Bits)
RelativeRel = (R_MIPS_64 << 8) | R_MIPS_REL32;
else
RelativeRel = R_MIPS_REL32;
}
template <class ELFT>
RelExpr MipsTargetInfo<ELFT>::getRelExpr(uint32_t Type,
const SymbolBody &S) const {
if (ELFT::Is64Bits)
// See comment in the calculateMips64RelChain.
Type &= 0xff;
switch (Type) {
default:
return R_ABS;
case R_MIPS_JALR:
return R_HINT;
case R_MIPS_GPREL16:
case R_MIPS_GPREL32:
return R_GOTREL;
case R_MIPS_26:
return R_PLT;
case R_MIPS_HI16:
case R_MIPS_LO16:
case R_MIPS_GOT_OFST:
// MIPS _gp_disp designates offset between start of function and 'gp'
// pointer into GOT. __gnu_local_gp is equal to the current value of
// the 'gp'. Therefore any relocations against them do not require
// dynamic relocation.
if (&S == ElfSym<ELFT>::MipsGpDisp)
return R_PC;
return R_ABS;
case R_MIPS_PC32:
case R_MIPS_PC16:
case R_MIPS_PC19_S2:
case R_MIPS_PC21_S2:
case R_MIPS_PC26_S2:
case R_MIPS_PCHI16:
case R_MIPS_PCLO16:
return R_PC;
case R_MIPS_GOT16:
if (S.isLocal())
return R_MIPS_GOT_LOCAL_PAGE;
// fallthrough
case R_MIPS_CALL16:
case R_MIPS_GOT_DISP:
if (!S.isPreemptible())
return R_MIPS_GOT_LOCAL;
return R_GOT_OFF;
case R_MIPS_GOT_PAGE:
return R_MIPS_GOT_LOCAL_PAGE;
}
}
template <class ELFT>
uint32_t MipsTargetInfo<ELFT>::getDynRel(uint32_t Type) const {
if (Type == R_MIPS_32 || Type == R_MIPS_64)
return RelativeRel;
StringRef S = getELFRelocationTypeName(EM_MIPS, Type);
error("relocation " + S + " cannot be used when making a shared object; "
"recompile with -fPIC.");
// Keep it going with a dummy value so that we can find more reloc errors.
return R_MIPS_32;
}
template <class ELFT>
void MipsTargetInfo<ELFT>::writeGotPlt(uint8_t *Buf, uint64_t Plt) const {
write32<ELFT::TargetEndianness>(Buf, Out<ELFT>::Plt->getVA());
}
static uint16_t mipsHigh(uint64_t V) { return (V + 0x8000) >> 16; }
template <endianness E, uint8_t BSIZE, uint8_t SHIFT>
static int64_t getPcRelocAddend(const uint8_t *Loc) {
uint32_t Instr = read32<E>(Loc);
uint32_t Mask = 0xffffffff >> (32 - BSIZE);
return SignExtend64<BSIZE + SHIFT>((Instr & Mask) << SHIFT);
}
template <endianness E, uint8_t BSIZE, uint8_t SHIFT>
static void applyMipsPcReloc(uint8_t *Loc, uint32_t Type, uint64_t V) {
uint32_t Mask = 0xffffffff >> (32 - BSIZE);
uint32_t Instr = read32<E>(Loc);
if (SHIFT > 0)
checkAlignment<(1 << SHIFT)>(V, Type);
checkInt<BSIZE + SHIFT>(V, Type);
write32<E>(Loc, (Instr & ~Mask) | ((V >> SHIFT) & Mask));
}
template <endianness E>
static void writeMipsHi16(uint8_t *Loc, uint64_t V) {
uint32_t Instr = read32<E>(Loc);
write32<E>(Loc, (Instr & 0xffff0000) | mipsHigh(V));
}
template <endianness E>
static void writeMipsLo16(uint8_t *Loc, uint64_t V) {
uint32_t Instr = read32<E>(Loc);
write32<E>(Loc, (Instr & 0xffff0000) | (V & 0xffff));
}
template <endianness E> static int16_t readSignedLo16(const uint8_t *Loc) {
return SignExtend32<16>(read32<E>(Loc) & 0xffff);
}
template <class ELFT>
void MipsTargetInfo<ELFT>::writePltZero(uint8_t *Buf) const {
const endianness E = ELFT::TargetEndianness;
write32<E>(Buf, 0x3c1c0000); // lui $28, %hi(&GOTPLT[0])
write32<E>(Buf + 4, 0x8f990000); // lw $25, %lo(&GOTPLT[0])($28)
write32<E>(Buf + 8, 0x279c0000); // addiu $28, $28, %lo(&GOTPLT[0])
write32<E>(Buf + 12, 0x031cc023); // subu $24, $24, $28
write32<E>(Buf + 16, 0x03e07825); // move $15, $31
write32<E>(Buf + 20, 0x0018c082); // srl $24, $24, 2
write32<E>(Buf + 24, 0x0320f809); // jalr $25
write32<E>(Buf + 28, 0x2718fffe); // subu $24, $24, 2
uint64_t Got = Out<ELFT>::GotPlt->getVA();
writeMipsHi16<E>(Buf, Got);
writeMipsLo16<E>(Buf + 4, Got);
writeMipsLo16<E>(Buf + 8, Got);
}
template <class ELFT>
void MipsTargetInfo<ELFT>::writePlt(uint8_t *Buf, uint64_t GotEntryAddr,
uint64_t PltEntryAddr, int32_t Index,
unsigned RelOff) const {
const endianness E = ELFT::TargetEndianness;
write32<E>(Buf, 0x3c0f0000); // lui $15, %hi(.got.plt entry)
write32<E>(Buf + 4, 0x8df90000); // l[wd] $25, %lo(.got.plt entry)($15)
write32<E>(Buf + 8, 0x03200008); // jr $25
write32<E>(Buf + 12, 0x25f80000); // addiu $24, $15, %lo(.got.plt entry)
writeMipsHi16<E>(Buf, GotEntryAddr);
writeMipsLo16<E>(Buf + 4, GotEntryAddr);
writeMipsLo16<E>(Buf + 12, GotEntryAddr);
}
template <class ELFT>
void MipsTargetInfo<ELFT>::writeThunk(uint8_t *Buf, uint64_t S) const {
// Write MIPS LA25 thunk code to call PIC function from the non-PIC one.
// See MipsTargetInfo::writeThunk for details.
const endianness E = ELFT::TargetEndianness;
write32<E>(Buf, 0x3c190000); // lui $25, %hi(func)
write32<E>(Buf + 4, 0x08000000); // j func
write32<E>(Buf + 8, 0x27390000); // addiu $25, $25, %lo(func)
write32<E>(Buf + 12, 0x00000000); // nop
writeMipsHi16<E>(Buf, S);
write32<E>(Buf + 4, 0x08000000 | (S >> 2));
writeMipsLo16<E>(Buf + 8, S);
}
template <class ELFT>
bool MipsTargetInfo<ELFT>::needsThunk(uint32_t Type, const InputFile &File,
const SymbolBody &S) const {
// Any MIPS PIC code function is invoked with its address in register $t9.
// So if we have a branch instruction from non-PIC code to the PIC one
// we cannot make the jump directly and need to create a small stubs
// to save the target function address.
// See page 3-38 ftp://www.linux-mips.org/pub/linux/mips/doc/ABI/mipsabi.pdf
if (Type != R_MIPS_26)
return false;
auto *F = dyn_cast<ELFFileBase<ELFT>>(&File);
if (!F)
return false;
// If current file has PIC code, LA25 stub is not required.
if (F->getObj().getHeader()->e_flags & EF_MIPS_PIC)
return false;
auto *D = dyn_cast<DefinedRegular<ELFT>>(&S);
if (!D || !D->Section)
return false;
// LA25 is required if target file has PIC code
// or target symbol is a PIC symbol.
return (D->Section->getFile()->getObj().getHeader()->e_flags & EF_MIPS_PIC) ||
(D->StOther & STO_MIPS_MIPS16) == STO_MIPS_PIC;
}
template <class ELFT>
uint64_t MipsTargetInfo<ELFT>::getImplicitAddend(const uint8_t *Buf,
uint32_t Type) const {
const endianness E = ELFT::TargetEndianness;
switch (Type) {
default:
return 0;
case R_MIPS_32:
case R_MIPS_GPREL32:
return read32<E>(Buf);
case R_MIPS_26:
// FIXME (simon): If the relocation target symbol is not a PLT entry
// we should use another expression for calculation:
// ((A << 2) | (P & 0xf0000000)) >> 2
return SignExtend64<28>((read32<E>(Buf) & 0x3ffffff) << 2);
case R_MIPS_GPREL16:
case R_MIPS_LO16:
case R_MIPS_PCLO16:
case R_MIPS_TLS_DTPREL_HI16:
case R_MIPS_TLS_DTPREL_LO16:
case R_MIPS_TLS_TPREL_HI16:
case R_MIPS_TLS_TPREL_LO16:
return readSignedLo16<E>(Buf);
case R_MIPS_PC16:
return getPcRelocAddend<E, 16, 2>(Buf);
case R_MIPS_PC19_S2:
return getPcRelocAddend<E, 19, 2>(Buf);
case R_MIPS_PC21_S2:
return getPcRelocAddend<E, 21, 2>(Buf);
case R_MIPS_PC26_S2:
return getPcRelocAddend<E, 26, 2>(Buf);
case R_MIPS_PC32:
return getPcRelocAddend<E, 32, 0>(Buf);
}
}
static std::pair<uint32_t, uint64_t> calculateMips64RelChain(uint32_t Type,
uint64_t Val) {
// MIPS N64 ABI packs multiple relocations into the single relocation
// record. In general, all up to three relocations can have arbitrary
// types. In fact, Clang and GCC uses only a few combinations. For now,
// we support two of them. That is allow to pass at least all LLVM
// test suite cases.
// <any relocation> / R_MIPS_SUB / R_MIPS_HI16 | R_MIPS_LO16
// <any relocation> / R_MIPS_64 / R_MIPS_NONE
// The first relocation is a 'real' relocation which is calculated
// using the corresponding symbol's value. The second and the third
// relocations used to modify result of the first one: extend it to
// 64-bit, extract high or low part etc. For details, see part 2.9 Relocation
// at the https://dmz-portal.mips.com/mw/images/8/82/007-4658-001.pdf
uint32_t Type2 = (Type >> 8) & 0xff;
uint32_t Type3 = (Type >> 16) & 0xff;
if (Type2 == R_MIPS_NONE && Type3 == R_MIPS_NONE)
return std::make_pair(Type, Val);
if (Type2 == R_MIPS_64 && Type3 == R_MIPS_NONE)
return std::make_pair(Type2, Val);
if (Type2 == R_MIPS_SUB && (Type3 == R_MIPS_HI16 || Type3 == R_MIPS_LO16))
return std::make_pair(Type3, -Val);
error("unsupported relocations combination " + Twine(Type));
return std::make_pair(Type & 0xff, Val);
}
template <class ELFT>
void MipsTargetInfo<ELFT>::relocateOne(uint8_t *Loc, uint32_t Type,
uint64_t Val) const {
const endianness E = ELFT::TargetEndianness;
// Thread pointer and DRP offsets from the start of TLS data area.
// https://www.linux-mips.org/wiki/NPTL
if (Type == R_MIPS_TLS_DTPREL_HI16 || Type == R_MIPS_TLS_DTPREL_LO16)
Val -= 0x8000;
else if (Type == R_MIPS_TLS_TPREL_HI16 || Type == R_MIPS_TLS_TPREL_LO16)
Val -= 0x7000;
if (ELFT::Is64Bits)
std::tie(Type, Val) = calculateMips64RelChain(Type, Val);
switch (Type) {
case R_MIPS_32:
case R_MIPS_GPREL32:
write32<E>(Loc, Val);
break;
case R_MIPS_64:
write64<E>(Loc, Val);
break;
case R_MIPS_26:
write32<E>(Loc, (read32<E>(Loc) & ~0x3ffffff) | (Val >> 2));
break;
case R_MIPS_GOT_DISP:
case R_MIPS_GOT_PAGE:
case R_MIPS_GOT16:
case R_MIPS_GPREL16:
checkInt<16>(Val, Type);
// fallthrough
case R_MIPS_CALL16:
case R_MIPS_GOT_OFST:
case R_MIPS_LO16:
case R_MIPS_PCLO16:
case R_MIPS_TLS_DTPREL_LO16:
case R_MIPS_TLS_TPREL_LO16:
writeMipsLo16<E>(Loc, Val);
break;
case R_MIPS_HI16:
case R_MIPS_PCHI16:
case R_MIPS_TLS_DTPREL_HI16:
case R_MIPS_TLS_TPREL_HI16:
writeMipsHi16<E>(Loc, Val);
break;
case R_MIPS_JALR:
// Ignore this optimization relocation for now
break;
case R_MIPS_PC16:
applyMipsPcReloc<E, 16, 2>(Loc, Type, Val);
break;
case R_MIPS_PC19_S2:
applyMipsPcReloc<E, 19, 2>(Loc, Type, Val);
break;
case R_MIPS_PC21_S2:
applyMipsPcReloc<E, 21, 2>(Loc, Type, Val);
break;
case R_MIPS_PC26_S2:
applyMipsPcReloc<E, 26, 2>(Loc, Type, Val);
break;
case R_MIPS_PC32:
applyMipsPcReloc<E, 32, 0>(Loc, Type, Val);
break;
default:
fatal("unrecognized reloc " + Twine(Type));
}
}
template <class ELFT>
bool MipsTargetInfo<ELFT>::usesOnlyLowPageBits(uint32_t Type) const {
return Type == R_MIPS_LO16 || Type == R_MIPS_GOT_OFST;
}
}
}
Reference in New Issue View Git Blame Copy Permalink