forked from OSchip/llvm-project
[ELF][MIPS] Add lazy relocation support for MIPS
The patch adds lazy relocation support for MIPS and R_MIPS_26 relocation handing. R_MIPS_26 relocation might require PLT entry creation. In that case it is fully supported by the patch. But if the relocation target is a local symbol we need to use a different expression to calculate the relocation result. This case is not implemented yet because there is no method to get know the kind of relocation target in the `relocateOne` routine. Differential Revision: http://reviews.llvm.org/D16982 llvm-svn: 260424
This commit is contained in:
Simon Atanasyan
parent
b3cce5d33a
commit
2287dc3bf8
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@ -195,6 +195,10 @@ template <class ELFT> class MipsTargetInfo final : public TargetInfo {
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public:
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MipsTargetInfo();
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unsigned getDynRel(unsigned Type) const override;
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void writeGotPlt(uint8_t *Buf, uint64_t Plt) const override;
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void writePltZero(uint8_t *Buf) const override;
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void writePlt(uint8_t *Buf, uint64_t GotEntryAddr, uint64_t PltEntryAddr,
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int32_t Index, unsigned RelOff) const override;
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void writeGotHeader(uint8_t *Buf) const override;
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bool needsCopyRel(uint32_t Type, const SymbolBody &S) const override;
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bool needsGot(uint32_t Type, SymbolBody &S) const override;
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@ -1389,8 +1393,13 @@ void AMDGPUTargetInfo::relocateOne(uint8_t *Loc, uint8_t *BufEnd, uint32_t Type,
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template <class ELFT> MipsTargetInfo<ELFT>::MipsTargetInfo() {
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GotHeaderEntriesNum = 2;
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GotPltHeaderEntriesNum = 2;
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PageSize = 65536;
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PltEntrySize = 16;
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PltZeroSize = 32;
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UseLazyBinding = true;
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CopyRel = R_MIPS_COPY;
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PltRel = R_MIPS_JUMP_SLOT;
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RelativeRel = R_MIPS_REL32;
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}
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@ -1429,24 +1438,8 @@ void MipsTargetInfo<ELFT>::writeGotHeader(uint8_t *Buf) const {
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}
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template <class ELFT>
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bool MipsTargetInfo<ELFT>::needsCopyRel(uint32_t Type,
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const SymbolBody &S) const {
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if (Config->Shared)
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return false;
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if (Type == R_MIPS_HI16 || Type == R_MIPS_LO16 || isRelRelative(Type))
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if (auto *SS = dyn_cast<SharedSymbol<ELFT>>(&S))
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return SS->Sym.getType() == STT_OBJECT;
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return false;
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}
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template <class ELFT>
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bool MipsTargetInfo<ELFT>::needsGot(uint32_t Type, SymbolBody &S) const {
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return Type == R_MIPS_GOT16 || Type == R_MIPS_CALL16;
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}
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template <class ELFT>
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bool MipsTargetInfo<ELFT>::needsPlt(uint32_t Type, SymbolBody &S) const {
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return false;
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void MipsTargetInfo<ELFT>::writeGotPlt(uint8_t *Buf, uint64_t Plt) const {
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write32<ELFT::TargetEndianness>(Buf, Out<ELFT>::Plt->getVA());
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}
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static uint16_t mipsHigh(uint64_t V) { return (V + 0x8000) >> 16; }
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@ -1464,6 +1457,71 @@ static void applyMipsPcReloc(uint8_t *Loc, uint32_t Type, uint64_t P,
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write32<E>(Loc, (Instr & ~Mask) | ((V >> SHIFT) & Mask));
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}
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template <endianness E>
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static void applyMipsHi16Reloc(uint8_t *Loc, uint64_t S, int64_t A) {
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uint32_t Instr = read32<E>(Loc);
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write32<E>(Loc, (Instr & 0xffff0000) | mipsHigh(S + A));
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}
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template <class ELFT>
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void MipsTargetInfo<ELFT>::writePltZero(uint8_t *Buf) const {
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const endianness E = ELFT::TargetEndianness;
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write32<E>(Buf, 0x3c1c0000); // lui $28, %hi(&GOTPLT[0])
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write32<E>(Buf + 4, 0x8f990000); // lw $25, %lo(&GOTPLT[0])($28)
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write32<E>(Buf + 8, 0x279c0000); // addiu $28, $28, %lo(&GOTPLT[0])
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write32<E>(Buf + 12, 0x031cc023); // subu $24, $24, $28
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write32<E>(Buf + 16, 0x03e07825); // move $15, $31
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write32<E>(Buf + 20, 0x0018c082); // srl $24, $24, 2
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write32<E>(Buf + 24, 0x0320f809); // jalr $25
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write32<E>(Buf + 28, 0x2718fffe); // subu $24, $24, 2
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uint64_t Got = Out<ELFT>::GotPlt->getVA();
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uint64_t Plt = Out<ELFT>::Plt->getVA();
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applyMipsHi16Reloc<E>(Buf, Got, 0);
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relocateOne(Buf + 4, Buf + 8, R_MIPS_LO16, Plt + 4, Got);
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relocateOne(Buf + 8, Buf + 12, R_MIPS_LO16, Plt + 8, Got);
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}
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template <class ELFT>
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void MipsTargetInfo<ELFT>::writePlt(uint8_t *Buf, uint64_t GotEntryAddr,
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uint64_t PltEntryAddr, int32_t Index,
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unsigned RelOff) const {
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const endianness E = ELFT::TargetEndianness;
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write32<E>(Buf, 0x3c0f0000); // lui $15, %hi(.got.plt entry)
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write32<E>(Buf + 4, 0x8df90000); // l[wd] $25, %lo(.got.plt entry)($15)
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write32<E>(Buf + 8, 0x03200008); // jr $25
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write32<E>(Buf + 12, 0x25f80000); // addiu $24, $15, %lo(.got.plt entry)
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applyMipsHi16Reloc<E>(Buf, GotEntryAddr, 0);
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relocateOne(Buf + 4, Buf + 8, R_MIPS_LO16, PltEntryAddr + 4, GotEntryAddr);
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relocateOne(Buf + 12, Buf + 16, R_MIPS_LO16, PltEntryAddr + 8, GotEntryAddr);
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}
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template <class ELFT>
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bool MipsTargetInfo<ELFT>::needsCopyRel(uint32_t Type,
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const SymbolBody &S) const {
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if (Config->Shared)
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return false;
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if (Type == R_MIPS_HI16 || Type == R_MIPS_LO16 || isRelRelative(Type))
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if (auto *SS = dyn_cast<SharedSymbol<ELFT>>(&S))
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return SS->Sym.getType() == STT_OBJECT;
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return false;
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}
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template <class ELFT>
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bool MipsTargetInfo<ELFT>::needsGot(uint32_t Type, SymbolBody &S) const {
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return needsPlt(Type, S) || Type == R_MIPS_GOT16 || Type == R_MIPS_CALL16;
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}
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template <class ELFT>
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bool MipsTargetInfo<ELFT>::needsPlt(uint32_t Type, SymbolBody &S) const {
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if (needsCopyRel(Type, S))
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return false;
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if (Type == R_MIPS_26 && canBePreempted(&S, false))
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return true;
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if (Type == R_MIPS_HI16 || Type == R_MIPS_LO16 || isRelRelative(Type))
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return S.isShared();
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return false;
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}
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template <class ELFT>
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void MipsTargetInfo<ELFT>::relocateOne(uint8_t *Loc, uint8_t *BufEnd,
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uint32_t Type, uint64_t P, uint64_t S,
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@ -1473,6 +1531,15 @@ void MipsTargetInfo<ELFT>::relocateOne(uint8_t *Loc, uint8_t *BufEnd,
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case R_MIPS_32:
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add32<E>(Loc, S);
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break;
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case R_MIPS_26: {
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uint32_t Instr = read32<E>(Loc);
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// FIXME (simon): If the relocation target symbol is not a PLT entry
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// we should use another expression for calculation:
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// ((A << 2) | (P & 0xf0000000)) >> 2
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S += SignExtend64<28>((Instr & 0x3ffffff) << 2);
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write32<E>(Loc, (Instr & ~0x3ffffff) | (S >> 2));
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break;
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}
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case R_MIPS_CALL16:
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case R_MIPS_GOT16: {
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int64_t V = S - getMipsGpAddr<ELFT>();
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@ -1496,10 +1563,10 @@ void MipsTargetInfo<ELFT>::relocateOne(uint8_t *Loc, uint8_t *BufEnd,
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if (PairedLoc) {
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uint64_t AHL = ((Instr & 0xffff) << 16) +
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SignExtend64<16>(read32<E>(PairedLoc) & 0xffff);
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write32<E>(Loc, (Instr & 0xffff0000) | mipsHigh(S + AHL));
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applyMipsHi16Reloc<E>(Loc, S, AHL);
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} else {
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warning("Can't find matching R_MIPS_LO16 relocation for R_MIPS_HI16");
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write32<E>(Loc, (Instr & 0xffff0000) | mipsHigh(S));
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applyMipsHi16Reloc<E>(Loc, S, 0);
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}
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break;
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}
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@ -4,9 +4,14 @@
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_foo:
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nop
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.globl foo
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.type foo, @function
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foo:
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.globl foo0
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.type foo0, @function
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foo0:
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nop
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.globl foo1
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.type foo1, @function
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foo1:
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nop
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.data
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@ -0,0 +1,97 @@
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# Check R_MIPS_26 relocation handling.
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# RUN: llvm-mc -filetype=obj -triple=mips-unknown-linux %s -o %t1.o
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# RUN: llvm-mc -filetype=obj -triple=mips-unknown-linux \
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# RUN: %S/Inputs/mips-dynamic.s -o %t2.o
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# RUN: ld.lld %t2.o -shared -o %t.so
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# RUN: ld.lld %t1.o %t.so -o %t.exe
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# RUN: llvm-objdump -d %t.exe | FileCheck %s
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# RUN: llvm-readobj -dynamic-table -s -r -mips-plt-got %t.exe \
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# RUN: | FileCheck -check-prefix=REL %s
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# REQUIRES: mips
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# CHECK: Disassembly of section .text:
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# CHECK-NEXT: bar:
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# CHECK-NEXT: 20000: 0c 00 80 06 jal 131096
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# ^-- 0x20018 loc
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# CHECK-NEXT: 20004: 00 00 00 00 nop
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#
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# CHECK: __start:
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# CHECK-NEXT: 20008: 0c 00 80 00 jal 131072
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# ^-- 0x20000 bar
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# CHECK-NEXT: 2000c: 00 00 00 00 nop
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# CHECK-NEXT: 20010: 0c 00 80 10 jal 131136
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# ^-- 0x20040 gotplt[foo0]
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# CHECK-NEXT: 20014: 00 00 00 00 nop
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#
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# CHECK: loc:
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# CHECK-NEXT: 20018: 00 00 00 00 nop
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# CHECK-NEXT: Disassembly of section .plt:
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# CHECK-NEXT: .plt:
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# CHECK-NEXT: 20020: 3c 1c 00 04 lui $gp, 4
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# CHECK-NEXT: 20024: 8f 99 00 04 lw $25, 4($gp)
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# CHECK-NEXT: 20028: 27 9c 00 04 addiu $gp, $gp, 4
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# CHECK-NEXT: 2002c: 03 1c c0 23 subu $24, $24, $gp
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# CHECK-NEXT: 20030: 03 e0 78 25 move $15, $ra
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# CHECK-NEXT: 20034: 00 18 c0 82 srl $24, $24, 2
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# CHECK-NEXT: 20038: 03 20 f8 09 jalr $25
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# CHECK-NEXT: 2003c: 27 18 ff fe addiu $24, $24, -2
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# CHECK-NEXT: 20040: 3c 0f 00 04 lui $15, 4
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# CHECK-NEXT: 20044: 8d f9 00 0c lw $25, 12($15)
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# CHECK-NEXT: 20048: 03 20 00 08 jr $25
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# CHECK-NEXT: 2004c: 25 f8 00 0c addiu $24, $15, 12
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# REL: Name: .plt
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# REL-NEXT: Type: SHT_PROGBITS
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# REL-NEXT: Flags [ (0x6)
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# REL-NEXT: SHF_ALLOC
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# REL-NEXT: SHF_EXECINSTR
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# REL-NEXT: ]
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# REL-NEXT: Address: 0x[[PLTADDR:[0-9A-F]+]]
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# REL: Name: .got.plt
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# REL-NEXT: Type: SHT_PROGBITS
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# REL-NEXT: Flags [ (0x3)
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# REL-NEXT: SHF_ALLOC
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# REL-NEXT: SHF_WRITE
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# REL-NEXT: ]
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# REL-NEXT: Address: 0x[[GOTPLTADDR:[0-9A-F]+]]
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# REL: Relocations [
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# REL-NEXT: Section (7) .rel.plt {
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# REL-NEXT: 0x[[PLTSLOT:[0-9A-F]+]] R_MIPS_JUMP_SLOT foo0 0x0
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# REL-NEXT: }
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# REL-NEXT: ]
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# REL: 0x70000032 MIPS_PLTGOT 0x[[GOTPLTADDR]]
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# REL: Primary GOT {
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# REL: Local entries [
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# REL-NEXT: ]
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# REL-NEXT: Global entries [
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# REL-NEXT: ]
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# REL: PLT GOT {
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# REL: Entries [
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# REL-NEXT: Entry {
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# REL-NEXT: Address: 0x[[PLTSLOT]]
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# REL-NEXT: Initial: 0x[[PLTADDR]]
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# REL-NEXT: Value: 0x0
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# REL-NEXT: Type: Function
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# REL-NEXT: Section: Undefined
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# REL-NEXT: Name: foo0
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# REL-NEXT: }
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# REL-NEXT: ]
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.text
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.globl bar
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bar:
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jal loc # R_MIPS_26 against .text + offset
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.globl __start
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__start:
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jal bar # R_MIPS_26 against global 'bar' from object file
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jal foo0 # R_MIPS_26 against 'foo0' from DSO
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loc:
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nop
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@ -1,4 +1,5 @@
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# Check creating of R_MIPS_COPY dynamic relocation.
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# Check creating of R_MIPS_COPY and R_MIPS_JUMP_SLOT dynamic relocations
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# and corresponding PLT entries.
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# RUN: llvm-mc -filetype=obj -triple=mips-unknown-linux %s -o %t.o
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# RUN: llvm-mc -filetype=obj -triple=mips-unknown-linux \
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@ -14,6 +15,10 @@
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# CHECK-NEXT: 0x{{[0-9A-F]+}} R_MIPS_COPY data0 0x0
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# CHECK-NEXT: 0x{{[0-9A-F]+}} R_MIPS_COPY data1 0x0
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# CHECK-NEXT: }
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# CHECK-NEXT: Section (8) .rel.plt {
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# CHECK-NEXT: 0x{{[0-9A-F]+}} R_MIPS_JUMP_SLOT foo0 0x0
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# CHECK-NEXT: 0x{{[0-9A-F]+}} R_MIPS_JUMP_SLOT foo1 0x0
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# CHECK-NEXT: }
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# CHECK-NEXT: ]
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# CHECK: Primary GOT {
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@ -22,11 +27,40 @@
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# CHECK-NEXT: Global entries [
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# CHECK-NEXT: ]
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# CHECK-NEXT: Number of TLS and multi-GOT entries: 0
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# CHECK-NEXT: }
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# CHECK: PLT GOT {
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# CHECK: Entries [
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# CHECK-NEXT: Entry {
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# CHECK-NEXT: Address: 0x{{[0-9A-F]+}}
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# CHECK-NEXT: Initial: 0x{{[0-9A-F]+}}
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# CHECK-NEXT: Value: 0x{{[0-9A-F]+}}
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# CHECK-NEXT: Type: Function
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# CHECK-NEXT: Section: Undefined
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# CHECK-NEXT: Name: foo0
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# CHECK-NEXT: }
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# CHECK-NEXT: Entry {
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# CHECK-NEXT: Address: 0x{{[0-9A-F]+}}
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# CHECK-NEXT: Initial: 0x{{[0-9A-F]+}}
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# CHECK-NEXT: Value: 0x{{[0-9A-F]+}}
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# CHECK-NEXT: Type: Function
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# CHECK-NEXT: Section: Undefined
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# CHECK-NEXT: Name: foo1
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# CHECK-NEXT: }
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# CHECK-NEXT: ]
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# CHECK-NEXT: }
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.text
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.globl __start
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__start:
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lui $t0,%hi(foo0) # R_MIPS_HI16 requires JUMP_SLOT/PLT entry
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# for DSO defined func.
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addi $t0,$t0,%lo(foo0)
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lui $t0,%hi(bar) # Does not require PLT for locally defined func.
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addi $t0,$t0,%lo(bar)
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lui $t0,%hi(loc) # Does not require PLT for local func.
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addi $t0,$t0,%lo(loc)
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lui $t0,%hi(data0) # R_MIPS_HI16 requires COPY rel for DSO defined data.
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addi $t0,$t0,%lo(data0)
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lui $t0,%hi(gd) # Does not require COPY rel for locally defined data.
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@ -34,9 +68,18 @@ __start:
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lui $t0,%hi(ld) # Does not require COPY rel for local data.
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addi $t0,$t0,%lo(ld)
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.globl bar
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.type bar, @function
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bar:
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nop
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loc:
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nop
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.data
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.globl gd
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gd:
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.word 0
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ld:
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.word data1+8-. # R_MIPS_PC32 requires COPY rel for DSO defined data.
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.word foo1+8-. # R_MIPS_PC32 requires JUMP_SLOT/PLT entry
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# for DSO defined func.
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