[lld] r260424 - [ELF][MIPS] Add lazy relocation support for MIPS
Simon Atanasyan via llvm-commits
llvm-commits at lists.llvm.org
Wed Feb 10 11:57:19 PST 2016
Author: atanasyan
Date: Wed Feb 10 13:57:19 2016
New Revision: 260424
URL: http://llvm.org/viewvc/llvm-project?rev=260424&view=rev
Log:
[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
Added:
lld/trunk/test/ELF/mips-26.s
Modified:
lld/trunk/ELF/Target.cpp
lld/trunk/test/ELF/Inputs/mips-dynamic.s
lld/trunk/test/ELF/mips-plt-copy.s
Modified: lld/trunk/ELF/Target.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/Target.cpp?rev=260424&r1=260423&r2=260424&view=diff
==============================================================================
--- lld/trunk/ELF/Target.cpp (original)
+++ lld/trunk/ELF/Target.cpp Wed Feb 10 13:57:19 2016
@@ -195,6 +195,10 @@ template <class ELFT> class MipsTargetIn
public:
MipsTargetInfo();
unsigned getDynRel(unsigned 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 writeGotHeader(uint8_t *Buf) const override;
bool needsCopyRel(uint32_t Type, const SymbolBody &S) const override;
bool needsGot(uint32_t Type, SymbolBody &S) const override;
@@ -1389,8 +1393,13 @@ void AMDGPUTargetInfo::relocateOne(uint8
template <class ELFT> MipsTargetInfo<ELFT>::MipsTargetInfo() {
GotHeaderEntriesNum = 2;
+ GotPltHeaderEntriesNum = 2;
PageSize = 65536;
+ PltEntrySize = 16;
+ PltZeroSize = 32;
+ UseLazyBinding = true;
CopyRel = R_MIPS_COPY;
+ PltRel = R_MIPS_JUMP_SLOT;
RelativeRel = R_MIPS_REL32;
}
@@ -1429,6 +1438,64 @@ void MipsTargetInfo<ELFT>::writeGotHeade
}
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 void applyMipsPcReloc(uint8_t *Loc, uint32_t Type, uint64_t P,
+ uint64_t S) {
+ uint32_t Mask = 0xffffffff >> (32 - BSIZE);
+ uint32_t Instr = read32<E>(Loc);
+ int64_t A = SignExtend64<BSIZE + SHIFT>((Instr & Mask) << SHIFT);
+ if (SHIFT > 0)
+ checkAlignment<(1 << SHIFT)>(S + A, Type);
+ int64_t V = S + A - P;
+ checkInt<BSIZE + SHIFT>(V, Type);
+ write32<E>(Loc, (Instr & ~Mask) | ((V >> SHIFT) & Mask));
+}
+
+template <endianness E>
+static void applyMipsHi16Reloc(uint8_t *Loc, uint64_t S, int64_t A) {
+ uint32_t Instr = read32<E>(Loc);
+ write32<E>(Loc, (Instr & 0xffff0000) | mipsHigh(S + A));
+}
+
+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();
+ uint64_t Plt = Out<ELFT>::Plt->getVA();
+ applyMipsHi16Reloc<E>(Buf, Got, 0);
+ relocateOne(Buf + 4, Buf + 8, R_MIPS_LO16, Plt + 4, Got);
+ relocateOne(Buf + 8, Buf + 12, R_MIPS_LO16, Plt + 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)
+ applyMipsHi16Reloc<E>(Buf, GotEntryAddr, 0);
+ relocateOne(Buf + 4, Buf + 8, R_MIPS_LO16, PltEntryAddr + 4, GotEntryAddr);
+ relocateOne(Buf + 12, Buf + 16, R_MIPS_LO16, PltEntryAddr + 8, GotEntryAddr);
+}
+
+template <class ELFT>
bool MipsTargetInfo<ELFT>::needsCopyRel(uint32_t Type,
const SymbolBody &S) const {
if (Config->Shared)
@@ -1441,29 +1508,20 @@ bool MipsTargetInfo<ELFT>::needsCopyRel(
template <class ELFT>
bool MipsTargetInfo<ELFT>::needsGot(uint32_t Type, SymbolBody &S) const {
- return Type == R_MIPS_GOT16 || Type == R_MIPS_CALL16;
+ return needsPlt(Type, S) || Type == R_MIPS_GOT16 || Type == R_MIPS_CALL16;
}
template <class ELFT>
bool MipsTargetInfo<ELFT>::needsPlt(uint32_t Type, SymbolBody &S) const {
+ if (needsCopyRel(Type, S))
+ return false;
+ if (Type == R_MIPS_26 && canBePreempted(&S, false))
+ return true;
+ if (Type == R_MIPS_HI16 || Type == R_MIPS_LO16 || isRelRelative(Type))
+ return S.isShared();
return false;
}
-static uint16_t mipsHigh(uint64_t V) { return (V + 0x8000) >> 16; }
-
-template <endianness E, uint8_t BSIZE, uint8_t SHIFT>
-static void applyMipsPcReloc(uint8_t *Loc, uint32_t Type, uint64_t P,
- uint64_t S) {
- uint32_t Mask = 0xffffffff >> (32 - BSIZE);
- uint32_t Instr = read32<E>(Loc);
- int64_t A = SignExtend64<BSIZE + SHIFT>((Instr & Mask) << SHIFT);
- if (SHIFT > 0)
- checkAlignment<(1 << SHIFT)>(S + A, Type);
- int64_t V = S + A - P;
- checkInt<BSIZE + SHIFT>(V, Type);
- write32<E>(Loc, (Instr & ~Mask) | ((V >> SHIFT) & Mask));
-}
-
template <class ELFT>
void MipsTargetInfo<ELFT>::relocateOne(uint8_t *Loc, uint8_t *BufEnd,
uint32_t Type, uint64_t P, uint64_t S,
@@ -1473,6 +1531,15 @@ void MipsTargetInfo<ELFT>::relocateOne(u
case R_MIPS_32:
add32<E>(Loc, S);
break;
+ case R_MIPS_26: {
+ uint32_t Instr = read32<E>(Loc);
+ // FIXME (simon): If the relocation target symbol is not a PLT entry
+ // we should use another expression for calculation:
+ // ((A << 2) | (P & 0xf0000000)) >> 2
+ S += SignExtend64<28>((Instr & 0x3ffffff) << 2);
+ write32<E>(Loc, (Instr & ~0x3ffffff) | (S >> 2));
+ break;
+ }
case R_MIPS_CALL16:
case R_MIPS_GOT16: {
int64_t V = S - getMipsGpAddr<ELFT>();
@@ -1496,10 +1563,10 @@ void MipsTargetInfo<ELFT>::relocateOne(u
if (PairedLoc) {
uint64_t AHL = ((Instr & 0xffff) << 16) +
SignExtend64<16>(read32<E>(PairedLoc) & 0xffff);
- write32<E>(Loc, (Instr & 0xffff0000) | mipsHigh(S + AHL));
+ applyMipsHi16Reloc<E>(Loc, S, AHL);
} else {
warning("Can't find matching R_MIPS_LO16 relocation for R_MIPS_HI16");
- write32<E>(Loc, (Instr & 0xffff0000) | mipsHigh(S));
+ applyMipsHi16Reloc<E>(Loc, S, 0);
}
break;
}
Modified: lld/trunk/test/ELF/Inputs/mips-dynamic.s
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/test/ELF/Inputs/mips-dynamic.s?rev=260424&r1=260423&r2=260424&view=diff
==============================================================================
--- lld/trunk/test/ELF/Inputs/mips-dynamic.s (original)
+++ lld/trunk/test/ELF/Inputs/mips-dynamic.s Wed Feb 10 13:57:19 2016
@@ -4,9 +4,14 @@
_foo:
nop
- .globl foo
- .type foo, @function
-foo:
+ .globl foo0
+ .type foo0, @function
+foo0:
+ nop
+
+ .globl foo1
+ .type foo1, @function
+foo1:
nop
.data
Added: lld/trunk/test/ELF/mips-26.s
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/test/ELF/mips-26.s?rev=260424&view=auto
==============================================================================
--- lld/trunk/test/ELF/mips-26.s (added)
+++ lld/trunk/test/ELF/mips-26.s Wed Feb 10 13:57:19 2016
@@ -0,0 +1,97 @@
+# Check R_MIPS_26 relocation handling.
+
+# RUN: llvm-mc -filetype=obj -triple=mips-unknown-linux %s -o %t1.o
+# RUN: llvm-mc -filetype=obj -triple=mips-unknown-linux \
+# RUN: %S/Inputs/mips-dynamic.s -o %t2.o
+# RUN: ld.lld %t2.o -shared -o %t.so
+# RUN: ld.lld %t1.o %t.so -o %t.exe
+# RUN: llvm-objdump -d %t.exe | FileCheck %s
+# RUN: llvm-readobj -dynamic-table -s -r -mips-plt-got %t.exe \
+# RUN: | FileCheck -check-prefix=REL %s
+
+# REQUIRES: mips
+
+# CHECK: Disassembly of section .text:
+# CHECK-NEXT: bar:
+# CHECK-NEXT: 20000: 0c 00 80 06 jal 131096
+# ^-- 0x20018 loc
+# CHECK-NEXT: 20004: 00 00 00 00 nop
+#
+# CHECK: __start:
+# CHECK-NEXT: 20008: 0c 00 80 00 jal 131072
+# ^-- 0x20000 bar
+# CHECK-NEXT: 2000c: 00 00 00 00 nop
+# CHECK-NEXT: 20010: 0c 00 80 10 jal 131136
+# ^-- 0x20040 gotplt[foo0]
+# CHECK-NEXT: 20014: 00 00 00 00 nop
+#
+# CHECK: loc:
+# CHECK-NEXT: 20018: 00 00 00 00 nop
+# CHECK-NEXT: Disassembly of section .plt:
+# CHECK-NEXT: .plt:
+# CHECK-NEXT: 20020: 3c 1c 00 04 lui $gp, 4
+# CHECK-NEXT: 20024: 8f 99 00 04 lw $25, 4($gp)
+# CHECK-NEXT: 20028: 27 9c 00 04 addiu $gp, $gp, 4
+# CHECK-NEXT: 2002c: 03 1c c0 23 subu $24, $24, $gp
+# CHECK-NEXT: 20030: 03 e0 78 25 move $15, $ra
+# CHECK-NEXT: 20034: 00 18 c0 82 srl $24, $24, 2
+# CHECK-NEXT: 20038: 03 20 f8 09 jalr $25
+# CHECK-NEXT: 2003c: 27 18 ff fe addiu $24, $24, -2
+# CHECK-NEXT: 20040: 3c 0f 00 04 lui $15, 4
+# CHECK-NEXT: 20044: 8d f9 00 0c lw $25, 12($15)
+# CHECK-NEXT: 20048: 03 20 00 08 jr $25
+# CHECK-NEXT: 2004c: 25 f8 00 0c addiu $24, $15, 12
+
+# REL: Name: .plt
+# REL-NEXT: Type: SHT_PROGBITS
+# REL-NEXT: Flags [ (0x6)
+# REL-NEXT: SHF_ALLOC
+# REL-NEXT: SHF_EXECINSTR
+# REL-NEXT: ]
+# REL-NEXT: Address: 0x[[PLTADDR:[0-9A-F]+]]
+
+# REL: Name: .got.plt
+# REL-NEXT: Type: SHT_PROGBITS
+# REL-NEXT: Flags [ (0x3)
+# REL-NEXT: SHF_ALLOC
+# REL-NEXT: SHF_WRITE
+# REL-NEXT: ]
+# REL-NEXT: Address: 0x[[GOTPLTADDR:[0-9A-F]+]]
+
+# REL: Relocations [
+# REL-NEXT: Section (7) .rel.plt {
+# REL-NEXT: 0x[[PLTSLOT:[0-9A-F]+]] R_MIPS_JUMP_SLOT foo0 0x0
+# REL-NEXT: }
+# REL-NEXT: ]
+
+# REL: 0x70000032 MIPS_PLTGOT 0x[[GOTPLTADDR]]
+
+# REL: Primary GOT {
+# REL: Local entries [
+# REL-NEXT: ]
+# REL-NEXT: Global entries [
+# REL-NEXT: ]
+# REL: PLT GOT {
+# REL: Entries [
+# REL-NEXT: Entry {
+# REL-NEXT: Address: 0x[[PLTSLOT]]
+# REL-NEXT: Initial: 0x[[PLTADDR]]
+# REL-NEXT: Value: 0x0
+# REL-NEXT: Type: Function
+# REL-NEXT: Section: Undefined
+# REL-NEXT: Name: foo0
+# REL-NEXT: }
+# REL-NEXT: ]
+
+ .text
+ .globl bar
+bar:
+ jal loc # R_MIPS_26 against .text + offset
+
+ .globl __start
+__start:
+ jal bar # R_MIPS_26 against global 'bar' from object file
+ jal foo0 # R_MIPS_26 against 'foo0' from DSO
+
+loc:
+ nop
Modified: lld/trunk/test/ELF/mips-plt-copy.s
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/test/ELF/mips-plt-copy.s?rev=260424&r1=260423&r2=260424&view=diff
==============================================================================
--- lld/trunk/test/ELF/mips-plt-copy.s (original)
+++ lld/trunk/test/ELF/mips-plt-copy.s Wed Feb 10 13:57:19 2016
@@ -1,4 +1,5 @@
-# Check creating of R_MIPS_COPY dynamic relocation.
+# Check creating of R_MIPS_COPY and R_MIPS_JUMP_SLOT dynamic relocations
+# and corresponding PLT entries.
# RUN: llvm-mc -filetype=obj -triple=mips-unknown-linux %s -o %t.o
# RUN: llvm-mc -filetype=obj -triple=mips-unknown-linux \
@@ -14,6 +15,10 @@
# CHECK-NEXT: 0x{{[0-9A-F]+}} R_MIPS_COPY data0 0x0
# CHECK-NEXT: 0x{{[0-9A-F]+}} R_MIPS_COPY data1 0x0
# CHECK-NEXT: }
+# CHECK-NEXT: Section (8) .rel.plt {
+# CHECK-NEXT: 0x{{[0-9A-F]+}} R_MIPS_JUMP_SLOT foo0 0x0
+# CHECK-NEXT: 0x{{[0-9A-F]+}} R_MIPS_JUMP_SLOT foo1 0x0
+# CHECK-NEXT: }
# CHECK-NEXT: ]
# CHECK: Primary GOT {
@@ -24,9 +29,38 @@
# CHECK-NEXT: Number of TLS and multi-GOT entries: 0
# CHECK-NEXT: }
+# CHECK: PLT GOT {
+# CHECK: Entries [
+# CHECK-NEXT: Entry {
+# CHECK-NEXT: Address: 0x{{[0-9A-F]+}}
+# CHECK-NEXT: Initial: 0x{{[0-9A-F]+}}
+# CHECK-NEXT: Value: 0x{{[0-9A-F]+}}
+# CHECK-NEXT: Type: Function
+# CHECK-NEXT: Section: Undefined
+# CHECK-NEXT: Name: foo0
+# CHECK-NEXT: }
+# CHECK-NEXT: Entry {
+# CHECK-NEXT: Address: 0x{{[0-9A-F]+}}
+# CHECK-NEXT: Initial: 0x{{[0-9A-F]+}}
+# CHECK-NEXT: Value: 0x{{[0-9A-F]+}}
+# CHECK-NEXT: Type: Function
+# CHECK-NEXT: Section: Undefined
+# CHECK-NEXT: Name: foo1
+# CHECK-NEXT: }
+# CHECK-NEXT: ]
+# CHECK-NEXT: }
+
.text
.globl __start
__start:
+ lui $t0,%hi(foo0) # R_MIPS_HI16 requires JUMP_SLOT/PLT entry
+ # for DSO defined func.
+ addi $t0,$t0,%lo(foo0)
+ lui $t0,%hi(bar) # Does not require PLT for locally defined func.
+ addi $t0,$t0,%lo(bar)
+ lui $t0,%hi(loc) # Does not require PLT for local func.
+ addi $t0,$t0,%lo(loc)
+
lui $t0,%hi(data0) # R_MIPS_HI16 requires COPY rel for DSO defined data.
addi $t0,$t0,%lo(data0)
lui $t0,%hi(gd) # Does not require COPY rel for locally defined data.
@@ -34,9 +68,18 @@ __start:
lui $t0,%hi(ld) # Does not require COPY rel for local data.
addi $t0,$t0,%lo(ld)
+ .globl bar
+ .type bar, @function
+bar:
+ nop
+loc:
+ nop
+
.data
.globl gd
gd:
.word 0
ld:
.word data1+8-. # R_MIPS_PC32 requires COPY rel for DSO defined data.
+ .word foo1+8-. # R_MIPS_PC32 requires JUMP_SLOT/PLT entry
+ # for DSO defined func.
More information about the llvm-commits
mailing list