diff options
author | Jim Grosbach <grosbach@apple.com> | 2012-09-26 21:27:45 +0000 |
---|---|---|
committer | Jim Grosbach <grosbach@apple.com> | 2012-09-26 21:27:45 +0000 |
commit | b7abea08409d4f15063b25e025f160a5469efd54 (patch) | |
tree | 6577a96f00807c9e4b8f0ca319ba823a3a8894ad /lib | |
parent | 2c79ecbd704c656178ffa43d5a58ebe3ca188b40 (diff) |
X86_32: Large Symbol+Offset relocations.
If the offset is more than 24-bits, it won't fit in a scattered
relocation offset field, so we fall back to using a non-scattered
relocation.
rdar://12358909
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@164724 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib')
-rw-r--r-- | lib/Target/X86/MCTargetDesc/X86MachObjectWriter.cpp | 48 |
1 files changed, 40 insertions, 8 deletions
diff --git a/lib/Target/X86/MCTargetDesc/X86MachObjectWriter.cpp b/lib/Target/X86/MCTargetDesc/X86MachObjectWriter.cpp index f0f1982d57..7ff058edbc 100644 --- a/lib/Target/X86/MCTargetDesc/X86MachObjectWriter.cpp +++ b/lib/Target/X86/MCTargetDesc/X86MachObjectWriter.cpp @@ -11,11 +11,13 @@ #include "MCTargetDesc/X86MCTargetDesc.h" #include "llvm/MC/MCAssembler.h" #include "llvm/MC/MCAsmLayout.h" +#include "llvm/MC/MCContext.h" #include "llvm/MC/MCMachObjectWriter.h" #include "llvm/MC/MCSectionMachO.h" #include "llvm/MC/MCValue.h" #include "llvm/ADT/Twine.h" #include "llvm/Support/ErrorHandling.h" +#include "llvm/Support/Format.h" #include "llvm/Object/MachOFormat.h" using namespace llvm; @@ -23,7 +25,7 @@ using namespace llvm::object; namespace { class X86MachObjectWriter : public MCMachObjectTargetWriter { - void RecordScatteredRelocation(MachObjectWriter *Writer, + bool RecordScatteredRelocation(MachObjectWriter *Writer, const MCAssembler &Asm, const MCAsmLayout &Layout, const MCFragment *Fragment, @@ -335,7 +337,7 @@ void X86MachObjectWriter::RecordX86_64Relocation(MachObjectWriter *Writer, Writer->addRelocation(Fragment->getParent(), MRE); } -void X86MachObjectWriter::RecordScatteredRelocation(MachObjectWriter *Writer, +bool X86MachObjectWriter::RecordScatteredRelocation(MachObjectWriter *Writer, const MCAssembler &Asm, const MCAsmLayout &Layout, const MCFragment *Fragment, @@ -381,6 +383,19 @@ void X86MachObjectWriter::RecordScatteredRelocation(MachObjectWriter *Writer, // Relocations are written out in reverse order, so the PAIR comes first. if (Type == macho::RIT_Difference || Type == macho::RIT_Generic_LocalDifference) { + // If the offset is too large to fit in a scattered relocation, + // we're hosed. It's an unfortunate limitation of the MachO format. + if (FixupOffset > 0xffffff) { + char Buffer[32]; + format("0x%x", FixupOffset).print(Buffer, sizeof(Buffer)); + Asm.getContext().FatalError(Fixup.getLoc(), + Twine("Section too large, can't encode " + "r_address (") + Buffer + + ") into 24 bits of scattered " + "relocation entry."); + llvm_unreachable("fatal error returned?!"); + } + macho::RelocationEntry MRE; MRE.Word0 = ((0 << 0) | (macho::RIT_Pair << 24) | @@ -389,6 +404,16 @@ void X86MachObjectWriter::RecordScatteredRelocation(MachObjectWriter *Writer, macho::RF_Scattered); MRE.Word1 = Value2; Writer->addRelocation(Fragment->getParent(), MRE); + } else { + // If the offset is more than 24-bits, it won't fit in a scattered + // relocation offset field, so we fall back to using a non-scattered + // relocation. This is a bit risky, as if the offset reaches out of + // the block and the linker is doing scattered loading on this + // symbol, things can go badly. + // + // Required for 'as' compatibility. + if (FixupOffset > 0xffffff) + return false; } macho::RelocationEntry MRE; @@ -399,6 +424,7 @@ void X86MachObjectWriter::RecordScatteredRelocation(MachObjectWriter *Writer, macho::RF_Scattered); MRE.Word1 = Value; Writer->addRelocation(Fragment->getParent(), MRE); + return true; } void X86MachObjectWriter::RecordTLVPRelocation(MachObjectWriter *Writer, @@ -469,9 +495,11 @@ void X86MachObjectWriter::RecordX86Relocation(MachObjectWriter *Writer, // If this is a difference or a defined symbol plus an offset, then we need a // scattered relocation entry. Differences always require scattered // relocations. - if (Target.getSymB()) - return RecordScatteredRelocation(Writer, Asm, Layout, Fragment, Fixup, - Target, Log2Size, FixedValue); + if (Target.getSymB()) { + RecordScatteredRelocation(Writer, Asm, Layout, Fragment, Fixup, + Target, Log2Size, FixedValue); + return; + } // Get the symbol data, if any. MCSymbolData *SD = 0; @@ -483,9 +511,13 @@ void X86MachObjectWriter::RecordX86Relocation(MachObjectWriter *Writer, uint32_t Offset = Target.getConstant(); if (IsPCRel) Offset += 1 << Log2Size; - if (Offset && SD && !Writer->doesSymbolRequireExternRelocation(SD)) - return RecordScatteredRelocation(Writer, Asm, Layout, Fragment, Fixup, - Target, Log2Size, FixedValue); + // Try to record the scattered relocation if needed. Fall back to non + // scattered if necessary (see comments in RecordScatteredRelocation() + // for details). + if (Offset && SD && !Writer->doesSymbolRequireExternRelocation(SD) && + RecordScatteredRelocation(Writer, Asm, Layout, Fragment, Fixup, + Target, Log2Size, FixedValue)) + return; // See <reloc.h>. uint32_t FixupOffset = Layout.getFragmentOffset(Fragment)+Fixup.getOffset(); |