[lld] r254461 - [ELF] MIPS paired R_MIPS_HI16/LO16 relocations support
Simon Atanasyan via llvm-commits
llvm-commits at lists.llvm.org
Tue Dec 1 13:24:46 PST 2015
Author: atanasyan
Date: Tue Dec 1 15:24:45 2015
New Revision: 254461
URL: http://llvm.org/viewvc/llvm-project?rev=254461&view=rev
Log:
[ELF] MIPS paired R_MIPS_HI16/LO16 relocations support
Some MIPS relocations including `R_MIPS_HI16/R_MIPS_LO16` use combined
addends. Such addend is calculated using addends of both paired relocations.
Each `R_MIPS_HI16` relocation is paired with the next `R_MIPS_LO16`
relocation. ABI requires to compute such combined addend in case of REL
relocation record format only.
For details see p. 4-17 at
ftp://www.linux-mips.org/pub/linux/mips/doc/ABI/mipsabi.pdf
This patch implements lookup of the next paired relocation suing new
`InputSectionBase::findPairedRelocLocation` method. The primary
disadvantage of this approach is that we put MIPS specific logic into
the common code. The next disadvantage is that we lookup `R_MIPS_LO16`
for each `R_MIPS_HI16` relocation, while in fact multiple `R_MIPS_HI16`
might be paired with the single `R_MIPS_LO16`. From the other side
this way allows us to keep `MipsTargetInfo` class stateless and implement
later relocation handling in parallel.
This patch does not support `R_MIPS_HI16/R_MIPS_LO16` relocations against
`_gp_disp` symbol. In that case the relocations use a special formula for
the calculation. That will be implemented later.
Differential Revision: http://reviews.llvm.org/D15112
Added:
lld/trunk/test/ELF/mips-hilo-hi-only.s
lld/trunk/test/ELF/mips-hilo.s
Modified:
lld/trunk/ELF/InputSection.cpp
lld/trunk/ELF/InputSection.h
lld/trunk/ELF/Target.cpp
lld/trunk/ELF/Target.h
Modified: lld/trunk/ELF/InputSection.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/InputSection.cpp?rev=254461&r1=254460&r2=254461&view=diff
==============================================================================
--- lld/trunk/ELF/InputSection.cpp (original)
+++ lld/trunk/ELF/InputSection.cpp Tue Dec 1 15:24:45 2015
@@ -94,9 +94,38 @@ bool InputSection<ELFT>::classof(const I
template <class ELFT>
template <bool isRela>
-void InputSectionBase<ELFT>::relocate(
- uint8_t *Buf, uint8_t *BufEnd,
- iterator_range<const Elf_Rel_Impl<ELFT, isRela> *> Rels) {
+uint8_t *
+InputSectionBase<ELFT>::findMipsPairedReloc(uint8_t *Buf, uint32_t Type,
+ RelIteratorRange<isRela> Rels) {
+ // Some MIPS relocations use addend calculated from addend of the relocation
+ // itself and addend of paired relocation. ABI requires to compute such
+ // combined addend in case of REL relocation record format only.
+ // See p. 4-17 at ftp://www.linux-mips.org/pub/linux/mips/doc/ABI/mipsabi.pdf
+ if (isRela || Config->EMachine != EM_MIPS)
+ return nullptr;
+ if (Type == R_MIPS_HI16)
+ Type = R_MIPS_LO16;
+ else if (Type == R_MIPS_PCHI16)
+ Type = R_MIPS_PCLO16;
+ else if (Type == R_MICROMIPS_HI16)
+ Type = R_MICROMIPS_LO16;
+ else
+ return nullptr;
+ for (const auto &RI : Rels) {
+ if (RI.getType(Config->Mips64EL) != Type)
+ continue;
+ uintX_t Offset = getOffset(RI.r_offset);
+ if (Offset == (uintX_t)-1)
+ return nullptr;
+ return Buf + Offset;
+ }
+ return nullptr;
+}
+
+template <class ELFT>
+template <bool isRela>
+void InputSectionBase<ELFT>::relocate(uint8_t *Buf, uint8_t *BufEnd,
+ RelIteratorRange<isRela> Rels) {
typedef Elf_Rel_Impl<ELFT, isRela> RelType;
size_t Num = Rels.end() - Rels.begin();
for (size_t I = 0; I < Num; ++I) {
@@ -109,6 +138,7 @@ void InputSectionBase<ELFT>::relocate(
uint8_t *BufLoc = Buf + Offset;
uintX_t AddrLoc = OutSec->getVA() + Offset;
+ auto NextRelocs = llvm::make_range(&RI, Rels.end());
if (Target->isTlsLocalDynamicReloc(Type) &&
!Target->isTlsOptimized(Type, nullptr)) {
@@ -123,7 +153,8 @@ void InputSectionBase<ELFT>::relocate(
const Elf_Shdr *SymTab = File->getSymbolTable();
if (SymIndex < SymTab->sh_info) {
uintX_t SymVA = getLocalRelTarget(*File, RI);
- Target->relocateOne(BufLoc, BufEnd, Type, AddrLoc, SymVA);
+ Target->relocateOne(BufLoc, BufEnd, Type, AddrLoc, SymVA,
+ findMipsPairedReloc(Buf, Type, NextRelocs));
continue;
}
@@ -161,7 +192,8 @@ void InputSectionBase<ELFT>::relocate(
continue;
}
Target->relocateOne(BufLoc, BufEnd, Type, AddrLoc,
- SymVA + getAddend<ELFT>(RI));
+ SymVA + getAddend<ELFT>(RI),
+ findMipsPairedReloc(Buf, Type, NextRelocs));
}
}
Modified: lld/trunk/ELF/InputSection.h
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/InputSection.h?rev=254461&r1=254460&r2=254461&view=diff
==============================================================================
--- lld/trunk/ELF/InputSection.h (original)
+++ lld/trunk/ELF/InputSection.h Tue Dec 1 15:24:45 2015
@@ -76,9 +76,16 @@ public:
InputSectionBase<ELFT> *getRelocTarget(const Elf_Rela &Rel);
template <bool isRela>
- void relocate(uint8_t *Buf, uint8_t *BufEnd,
- llvm::iterator_range<
- const llvm::object::Elf_Rel_Impl<ELFT, isRela> *> Rels);
+ using RelIteratorRange =
+ llvm::iterator_range<const llvm::object::Elf_Rel_Impl<ELFT, isRela> *>;
+
+ template <bool isRela>
+ void relocate(uint8_t *Buf, uint8_t *BufEnd, RelIteratorRange<isRela> Rels);
+
+private:
+ template <bool isRela>
+ uint8_t *findMipsPairedReloc(uint8_t *Buf, uint32_t Type,
+ RelIteratorRange<isRela> Rels);
};
template <class ELFT>
Modified: lld/trunk/ELF/Target.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/Target.cpp?rev=254461&r1=254460&r2=254461&view=diff
==============================================================================
--- lld/trunk/ELF/Target.cpp (original)
+++ lld/trunk/ELF/Target.cpp Tue Dec 1 15:24:45 2015
@@ -87,7 +87,7 @@ public:
bool relocNeedsGot(uint32_t Type, const SymbolBody &S) const override;
bool relocNeedsPlt(uint32_t Type, const SymbolBody &S) const override;
void relocateOne(uint8_t *Loc, uint8_t *BufEnd, uint32_t Type, uint64_t P,
- uint64_t SA) const override;
+ uint64_t SA, uint8_t *PairedLoc = nullptr) const override;
};
class X86_64TargetInfo final : public TargetInfo {
@@ -106,7 +106,7 @@ public:
bool relocNeedsGot(uint32_t Type, const SymbolBody &S) const override;
bool relocNeedsPlt(uint32_t Type, const SymbolBody &S) const override;
void relocateOne(uint8_t *Loc, uint8_t *BufEnd, uint32_t Type, uint64_t P,
- uint64_t SA) const override;
+ uint64_t SA, uint8_t *PairedLoc = nullptr) const override;
bool isRelRelative(uint32_t Type) const override;
bool isTlsOptimized(unsigned Type, const SymbolBody *S) const override;
unsigned relocateTlsOptimize(uint8_t *Loc, uint8_t *BufEnd, uint32_t Type,
@@ -133,7 +133,7 @@ public:
bool relocNeedsGot(uint32_t Type, const SymbolBody &S) const override;
bool relocNeedsPlt(uint32_t Type, const SymbolBody &S) const override;
void relocateOne(uint8_t *Loc, uint8_t *BufEnd, uint32_t Type, uint64_t P,
- uint64_t SA) const override;
+ uint64_t SA, uint8_t *PairedLoc = nullptr) const override;
bool isRelRelative(uint32_t Type) const override;
};
@@ -150,7 +150,7 @@ public:
bool relocNeedsGot(uint32_t Type, const SymbolBody &S) const override;
bool relocNeedsPlt(uint32_t Type, const SymbolBody &S) const override;
void relocateOne(uint8_t *Loc, uint8_t *BufEnd, uint32_t Type, uint64_t P,
- uint64_t SA) const override;
+ uint64_t SA, uint8_t *PairedLoc = nullptr) const override;
};
template <class ELFT> class MipsTargetInfo final : public TargetInfo {
@@ -166,7 +166,7 @@ public:
bool relocNeedsGot(uint32_t Type, const SymbolBody &S) const override;
bool relocNeedsPlt(uint32_t Type, const SymbolBody &S) const override;
void relocateOne(uint8_t *Loc, uint8_t *BufEnd, uint32_t Type, uint64_t P,
- uint64_t SA) const override;
+ uint64_t SA, uint8_t *PairedLoc = nullptr) const override;
};
} // anonymous namespace
@@ -308,7 +308,8 @@ bool X86TargetInfo::relocNeedsPlt(uint32
}
void X86TargetInfo::relocateOne(uint8_t *Loc, uint8_t *BufEnd, uint32_t Type,
- uint64_t P, uint64_t SA) const {
+ uint64_t P, uint64_t SA,
+ uint8_t *PairedLoc) const {
switch (Type) {
case R_386_32:
add32le(Loc, SA);
@@ -581,7 +582,8 @@ unsigned X86_64TargetInfo::relocateTlsOp
}
void X86_64TargetInfo::relocateOne(uint8_t *Loc, uint8_t *BufEnd, uint32_t Type,
- uint64_t P, uint64_t SA) const {
+ uint64_t P, uint64_t SA,
+ uint8_t *PairedLoc) const {
switch (Type) {
case R_X86_64_32:
checkUInt<32>(SA, Type);
@@ -728,7 +730,8 @@ bool PPC64TargetInfo::isRelRelative(uint
}
void PPC64TargetInfo::relocateOne(uint8_t *Loc, uint8_t *BufEnd, uint32_t Type,
- uint64_t P, uint64_t SA) const {
+ uint64_t P, uint64_t SA,
+ uint8_t *PairedLoc) const {
uint64_t TB = getPPC64TocBase();
// For a TOC-relative relocation, adjust the addend and proceed in terms of
@@ -933,8 +936,8 @@ static uint64_t getAArch64Page(uint64_t
}
void AArch64TargetInfo::relocateOne(uint8_t *Loc, uint8_t *BufEnd,
- uint32_t Type, uint64_t P,
- uint64_t SA) const {
+ uint32_t Type, uint64_t P, uint64_t SA,
+ uint8_t *PairedLoc) const {
switch (Type) {
case R_AARCH64_ABS16:
checkIntUInt<16>(SA, Type);
@@ -1046,13 +1049,31 @@ bool MipsTargetInfo<ELFT>::relocNeedsPlt
template <class ELFT>
void MipsTargetInfo<ELFT>::relocateOne(uint8_t *Loc, uint8_t *BufEnd,
- uint32_t Type, uint64_t P,
- uint64_t SA) const {
+ uint32_t Type, uint64_t P, uint64_t SA,
+ uint8_t *PairedLoc) const {
const endianness E = ELFT::TargetEndianness;
switch (Type) {
case R_MIPS_32:
add32<E>(Loc, SA);
break;
+ case R_MIPS_HI16: {
+ uint32_t Instr = read32<E>(Loc);
+ if (PairedLoc) {
+ uint64_t AHL = ((Instr & 0xffff) << 16) +
+ llvm::SignExtend64<16>(read32<E>(PairedLoc) & 0xffff);
+ write32<E>(Loc, (Instr & 0xffff0000) | (((SA + AHL) >> 16) & 0xffff));
+ } else {
+ warning("Can't find matching R_MIPS_LO16 relocation for R_MIPS_HI16");
+ write32<E>(Loc, (Instr & 0xffff0000) | ((SA >> 16) & 0xffff));
+ }
+ break;
+ }
+ case R_MIPS_LO16: {
+ uint32_t Instr = read32<E>(Loc);
+ int64_t AHL = llvm::SignExtend64<16>(Instr & 0xffff);
+ write32<E>(Loc, (Instr & 0xffff0000) | ((SA + AHL) & 0xffff));
+ break;
+ }
case R_MIPS_CALL16:
case R_MIPS_GOT16: {
int64_t V = SA - getMipsGpAddr<ELFT>();
Modified: lld/trunk/ELF/Target.h
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/Target.h?rev=254461&r1=254460&r2=254461&view=diff
==============================================================================
--- lld/trunk/ELF/Target.h (original)
+++ lld/trunk/ELF/Target.h Tue Dec 1 15:24:45 2015
@@ -57,7 +57,8 @@ public:
virtual bool relocNeedsGot(uint32_t Type, const SymbolBody &S) const = 0;
virtual bool relocNeedsPlt(uint32_t Type, const SymbolBody &S) const = 0;
virtual void relocateOne(uint8_t *Loc, uint8_t *BufEnd, uint32_t Type,
- uint64_t P, uint64_t SA) const = 0;
+ uint64_t P, uint64_t SA,
+ uint8_t *PairedLoc = nullptr) const = 0;
virtual bool isTlsOptimized(unsigned Type, const SymbolBody *S) const;
virtual unsigned relocateTlsOptimize(uint8_t *Loc, uint8_t *BufEnd,
uint32_t Type, uint64_t P,
Added: lld/trunk/test/ELF/mips-hilo-hi-only.s
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/test/ELF/mips-hilo-hi-only.s?rev=254461&view=auto
==============================================================================
--- lld/trunk/test/ELF/mips-hilo-hi-only.s (added)
+++ lld/trunk/test/ELF/mips-hilo-hi-only.s Tue Dec 1 15:24:45 2015
@@ -0,0 +1,22 @@
+# Check warning on orphaned R_MIPS_HI16 relocations.
+
+# RUN: llvm-mc -filetype=obj -triple=mips-unknown-linux %s -o %t.o
+# RUN: ld.lld %t.o -o %t.exe 2>&1 | FileCheck -check-prefix=WARN %s
+# RUN: llvm-objdump -d -t %t.exe | FileCheck %s
+
+# REQUIRES: mips
+
+ .text
+ .globl __start
+__start:
+ lui $t0,%hi(__start+0x10000)
+
+# WARN: Can't find matching R_MIPS_LO16 relocation for R_MIPS_HI16
+
+# CHECK: Disassembly of section .text:
+# CHECK-NEXT: __start:
+# CHECK-NEXT: 20000: 3c 08 00 02 lui $8, 2
+# ^-- %hi(__start) w/o addend
+
+# CHECK: SYMBOL TABLE:
+# CHECK: 0020000 .text 00000000 __start
Added: lld/trunk/test/ELF/mips-hilo.s
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/test/ELF/mips-hilo.s?rev=254461&view=auto
==============================================================================
--- lld/trunk/test/ELF/mips-hilo.s (added)
+++ lld/trunk/test/ELF/mips-hilo.s Tue Dec 1 15:24:45 2015
@@ -0,0 +1,53 @@
+# Check R_MIPS_HI16 / LO16 relocations calculation.
+
+# RUN: llvm-mc -filetype=obj -triple=mips-unknown-linux %s -o %t.o
+# RUN: ld.lld %t.o -o %t.exe
+# RUN: llvm-objdump -d -t %t.exe | FileCheck %s
+
+# REQUIRES: mips
+
+ .text
+ .globl __start
+__start:
+ lui $t0,%hi(__start)
+ lui $t1,%hi(g1)
+ addi $t0,$t0,%lo(__start+4)
+ addi $t0,$t0,%lo(g1+8)
+
+ lui $t0,%hi(l1+0x10000)
+ lui $t1,%hi(l1+0x20000)
+ addi $t0,$t0,%lo(l1+(-4))
+
+ .data
+ .type l1, at object
+ .size l1,4
+l1:
+ .word 0
+
+ .globl g1
+ .type g1, at object
+ .size g1,4
+g1:
+ .word 0
+
+# CHECK: Disassembly of section .text:
+# CHECK-NEXT: __start:
+# CHECK-NEXT: 20000: 3c 08 00 02 lui $8, 2
+# ^-- %hi(__start+4)
+# CHECK-NEXT: 20004: 3c 09 00 03 lui $9, 3
+# ^-- %hi(g1+8)
+# CHECK-NEXT: 20008: 21 08 00 04 addi $8, $8, 4
+# ^-- %lo(__start+4)
+# CHECK-NEXT: 2000c: 21 08 00 0c addi $8, $8, 12
+# ^-- %lo(g1+8)
+# CHECK-NEXT: 20010: 3c 08 00 03 lui $8, 3
+# ^-- %hi(l1+0x10000-4)
+# CHECK-NEXT: 20014: 3c 09 00 04 lui $9, 4
+# ^-- %hi(l1+0x20000-4)
+# CHECK-NEXT: 20018: 21 08 ff fc addi $8, $8, -4
+# ^-- %lo(l1-4)
+
+# CHECK: SYMBOL TABLE:
+# CHECK: 0030000 l .data 00000004 l1
+# CHECK: 0020000 .text 00000000 __start
+# CHECK: 0030004 g .data 00000004 g1
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