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llvm-mirror/lib/ExecutionEngine/JITLink/EHFrameSupport.cpp
Lang Hames 49d6de165d [JITLink] Switch from StringRef to ArrayRef<char>, add some generic x86-64 utils 
Adds utilities for creating anonymous pointers and jump stubs to x86_64.h. These
are used by the GOT and Stubs builder, but may also be used by pass writers who
want to create pointer stubs for indirection.

This patch also switches the underlying type for LinkGraph content from
StringRef to ArrayRef<char>. This avoids any confusion when working with buffers
that contain null bytes in the middle like, for example, a newly added null
pointer content array. ;)
2021-03-30 21:07:24 -07:00

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//===-------- JITLink_EHFrameSupport.cpp - JITLink eh-frame utils ---------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include "EHFrameSupportImpl.h"
#include "llvm/BinaryFormat/Dwarf.h"
#include "llvm/Config/config.h"
#include "llvm/ExecutionEngine/Orc/TargetProcess/RegisterEHFrames.h"
#include "llvm/Support/DynamicLibrary.h"
#define DEBUG_TYPE "jitlink"
namespace llvm {
namespace jitlink {
EHFrameSplitter::EHFrameSplitter(StringRef EHFrameSectionName)
: EHFrameSectionName(EHFrameSectionName) {}
Error EHFrameSplitter::operator()(LinkGraph &G) {
auto *EHFrame = G.findSectionByName(EHFrameSectionName);
if (!EHFrame) {
LLVM_DEBUG({
dbgs() << "EHFrameSplitter: No " << EHFrameSectionName
<< " section. Nothing to do\n";
});
return Error::success();
}
LLVM_DEBUG({
dbgs() << "EHFrameSplitter: Processing " << EHFrameSectionName << "...\n";
});
DenseMap<Block *, LinkGraph::SplitBlockCache> Caches;
{
// Pre-build the split caches.
for (auto *B : EHFrame->blocks())
Caches[B] = LinkGraph::SplitBlockCache::value_type();
for (auto *Sym : EHFrame->symbols())
Caches[&Sym->getBlock()]->push_back(Sym);
for (auto *B : EHFrame->blocks())
llvm::sort(*Caches[B], [](const Symbol *LHS, const Symbol *RHS) {
return LHS->getOffset() > RHS->getOffset();
});
}
// Iterate over blocks (we do this by iterating over Caches entries rather
// than EHFrame->blocks() as we will be inserting new blocks along the way,
// which would invalidate iterators in the latter sequence.
for (auto &KV : Caches) {
auto &B = *KV.first;
auto &BCache = KV.second;
if (auto Err = processBlock(G, B, BCache))
return Err;
}
return Error::success();
}
Error EHFrameSplitter::processBlock(LinkGraph &G, Block &B,
LinkGraph::SplitBlockCache &Cache) {
LLVM_DEBUG({
dbgs() << " Processing block at " << formatv("{0:x16}", B.getAddress())
<< "\n";
});
// eh-frame should not contain zero-fill blocks.
if (B.isZeroFill())
return make_error<JITLinkError>("Unexpected zero-fill block in " +
EHFrameSectionName + " section");
if (B.getSize() == 0) {
LLVM_DEBUG(dbgs() << " Block is empty. Skipping.\n");
return Error::success();
}
BinaryStreamReader BlockReader(
StringRef(B.getContent().data(), B.getContent().size()),
G.getEndianness());
while (true) {
uint64_t RecordStartOffset = BlockReader.getOffset();
LLVM_DEBUG({
dbgs() << " Processing CFI record at "
<< formatv("{0:x16}", B.getAddress()) << "\n";
});
uint32_t Length;
if (auto Err = BlockReader.readInteger(Length))
return Err;
if (Length != 0xffffffff) {
if (auto Err = BlockReader.skip(Length))
return Err;
} else {
uint64_t ExtendedLength;
if (auto Err = BlockReader.readInteger(ExtendedLength))
return Err;
if (auto Err = BlockReader.skip(ExtendedLength))
return Err;
}
// If this was the last block then there's nothing to split
if (BlockReader.empty()) {
LLVM_DEBUG(dbgs() << " Extracted " << B << "\n");
return Error::success();
}
uint64_t BlockSize = BlockReader.getOffset() - RecordStartOffset;
auto &NewBlock = G.splitBlock(B, BlockSize);
(void)NewBlock;
LLVM_DEBUG(dbgs() << " Extracted " << NewBlock << "\n");
}
}
EHFrameEdgeFixer::EHFrameEdgeFixer(StringRef EHFrameSectionName,
unsigned PointerSize, Edge::Kind Delta64,
Edge::Kind Delta32, Edge::Kind NegDelta32)
: EHFrameSectionName(EHFrameSectionName), PointerSize(PointerSize),
Delta64(Delta64), Delta32(Delta32), NegDelta32(NegDelta32) {}
Error EHFrameEdgeFixer::operator()(LinkGraph &G) {
auto *EHFrame = G.findSectionByName(EHFrameSectionName);
if (!EHFrame) {
LLVM_DEBUG({
dbgs() << "EHFrameEdgeFixer: No " << EHFrameSectionName
<< " section. Nothing to do\n";
});
return Error::success();
}
// Check that we support the graph's pointer size.
if (G.getPointerSize() != 4 && G.getPointerSize() != 8)
return make_error<JITLinkError>(
"EHFrameEdgeFixer only supports 32 and 64 bit targets");
LLVM_DEBUG({
dbgs() << "EHFrameEdgeFixer: Processing " << EHFrameSectionName << "...\n";
});
ParseContext PC(G);
// Build a map of all blocks and symbols in the text sections. We will use
// these for finding / building edge targets when processing FDEs.
for (auto &Sec : G.sections()) {
PC.AddrToSyms.addSymbols(Sec.symbols());
if (auto Err = PC.AddrToBlock.addBlocks(Sec.blocks(),
BlockAddressMap::includeNonNull))
return Err;
}
// Sort eh-frame blocks into address order to ensure we visit CIEs before
// their child FDEs.
std::vector<Block *> EHFrameBlocks;
for (auto *B : EHFrame->blocks())
EHFrameBlocks.push_back(B);
llvm::sort(EHFrameBlocks, [](const Block *LHS, const Block *RHS) {
return LHS->getAddress() < RHS->getAddress();
});
// Loop over the blocks in address order.
for (auto *B : EHFrameBlocks)
if (auto Err = processBlock(PC, *B))
return Err;
return Error::success();
}
Error EHFrameEdgeFixer::processBlock(ParseContext &PC, Block &B) {
LLVM_DEBUG({
dbgs() << " Processing block at " << formatv("{0:x16}", B.getAddress())
<< "\n";
});
// eh-frame should not contain zero-fill blocks.
if (B.isZeroFill())
return make_error<JITLinkError>("Unexpected zero-fill block in " +
EHFrameSectionName + " section");
if (B.getSize() == 0) {
LLVM_DEBUG(dbgs() << " Block is empty. Skipping.\n");
return Error::success();
}
// Find the offsets of any existing edges from this block.
BlockEdgeMap BlockEdges;
for (auto &E : B.edges())
if (E.isRelocation()) {
if (BlockEdges.count(E.getOffset()))
return make_error<JITLinkError>(
"Multiple relocations at offset " +
formatv("{0:x16}", E.getOffset()) + " in " + EHFrameSectionName +
" block at address " + formatv("{0:x16}", B.getAddress()));
BlockEdges[E.getOffset()] = EdgeTarget(E);
}
CIEInfosMap CIEInfos;
BinaryStreamReader BlockReader(
StringRef(B.getContent().data(), B.getContent().size()),
PC.G.getEndianness());
while (!BlockReader.empty()) {
size_t RecordStartOffset = BlockReader.getOffset();
LLVM_DEBUG({
dbgs() << " Processing CFI record at "
<< formatv("{0:x16}", B.getAddress() + RecordStartOffset) << "\n";
});
// Get the record length.
size_t RecordRemaining;
{
uint32_t Length;
if (auto Err = BlockReader.readInteger(Length))
return Err;
// If Length < 0xffffffff then use the regular length field, otherwise
// read the extended length field.
if (Length != 0xffffffff)
RecordRemaining = Length;
else {
uint64_t ExtendedLength;
if (auto Err = BlockReader.readInteger(ExtendedLength))
return Err;
RecordRemaining = ExtendedLength;
}
}
if (BlockReader.bytesRemaining() < RecordRemaining)
return make_error<JITLinkError>(
"Incomplete CFI record at " +
formatv("{0:x16}", B.getAddress() + RecordStartOffset));
// Read the CIE delta for this record.
uint64_t CIEDeltaFieldOffset = BlockReader.getOffset() - RecordStartOffset;
uint32_t CIEDelta;
if (auto Err = BlockReader.readInteger(CIEDelta))
return Err;
if (CIEDelta == 0) {
if (auto Err = processCIE(PC, B, RecordStartOffset,
CIEDeltaFieldOffset + RecordRemaining,
CIEDeltaFieldOffset))
return Err;
} else {
if (auto Err = processFDE(PC, B, RecordStartOffset,
CIEDeltaFieldOffset + RecordRemaining,
CIEDeltaFieldOffset, CIEDelta, BlockEdges))
return Err;
}
// Move to the next record.
BlockReader.setOffset(RecordStartOffset + CIEDeltaFieldOffset +
RecordRemaining);
}
return Error::success();
}
Error EHFrameEdgeFixer::processCIE(ParseContext &PC, Block &B,
size_t RecordOffset, size_t RecordLength,
size_t CIEDeltaFieldOffset) {
LLVM_DEBUG(dbgs() << " Record is CIE\n");
auto RecordContent = B.getContent().slice(RecordOffset, RecordLength);
BinaryStreamReader RecordReader(
StringRef(RecordContent.data(), RecordContent.size()),
PC.G.getEndianness());
// Skip past the CIE delta field: we've already processed this far.
RecordReader.setOffset(CIEDeltaFieldOffset + 4);
auto &CIESymbol =
PC.G.addAnonymousSymbol(B, RecordOffset, RecordLength, false, false);
CIEInformation CIEInfo(CIESymbol);
uint8_t Version = 0;
if (auto Err = RecordReader.readInteger(Version))
return Err;
if (Version != 0x01)
return make_error<JITLinkError>("Bad CIE version " + Twine(Version) +
" (should be 0x01) in eh-frame");
auto AugInfo = parseAugmentationString(RecordReader);
if (!AugInfo)
return AugInfo.takeError();
// Skip the EH Data field if present.
if (AugInfo->EHDataFieldPresent)
if (auto Err = RecordReader.skip(PC.G.getPointerSize()))
return Err;
// Read and sanity check the code alignment factor.
{
uint64_t CodeAlignmentFactor = 0;
if (auto Err = RecordReader.readULEB128(CodeAlignmentFactor))
return Err;
if (CodeAlignmentFactor != 1)
return make_error<JITLinkError>("Unsupported CIE code alignment factor " +
Twine(CodeAlignmentFactor) +
" (expected 1)");
}
// Read and sanity check the data alignment factor.
{
int64_t DataAlignmentFactor = 0;
if (auto Err = RecordReader.readSLEB128(DataAlignmentFactor))
return Err;
if (DataAlignmentFactor != -8)
return make_error<JITLinkError>("Unsupported CIE data alignment factor " +
Twine(DataAlignmentFactor) +
" (expected -8)");
}
// Skip the return address register field.
if (auto Err = RecordReader.skip(1))
return Err;
uint64_t AugmentationDataLength = 0;
if (auto Err = RecordReader.readULEB128(AugmentationDataLength))
return Err;
uint32_t AugmentationDataStartOffset = RecordReader.getOffset();
uint8_t *NextField = &AugInfo->Fields[0];
while (uint8_t Field = *NextField++) {
switch (Field) {
case 'L': {
CIEInfo.FDEsHaveLSDAField = true;
uint8_t LSDAPointerEncoding;
if (auto Err = RecordReader.readInteger(LSDAPointerEncoding))
return Err;
if (!isSupportedPointerEncoding(LSDAPointerEncoding))
return make_error<JITLinkError>(
"Unsupported LSDA pointer encoding " +
formatv("{0:x2}", LSDAPointerEncoding) + " in CIE at " +
formatv("{0:x16}", CIESymbol.getAddress()));
CIEInfo.LSDAPointerEncoding = LSDAPointerEncoding;
break;
}
case 'P': {
uint8_t PersonalityPointerEncoding = 0;
if (auto Err = RecordReader.readInteger(PersonalityPointerEncoding))
return Err;
if (PersonalityPointerEncoding !=
(dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
dwarf::DW_EH_PE_sdata4))
return make_error<JITLinkError>(
"Unspported personality pointer "
"encoding " +
formatv("{0:x2}", PersonalityPointerEncoding) + " in CIE at " +
formatv("{0:x16}", CIESymbol.getAddress()));
uint32_t PersonalityPointerAddress;
if (auto Err = RecordReader.readInteger(PersonalityPointerAddress))
return Err;
break;
}
case 'R': {
uint8_t FDEPointerEncoding;
if (auto Err = RecordReader.readInteger(FDEPointerEncoding))
return Err;
if (!isSupportedPointerEncoding(FDEPointerEncoding))
return make_error<JITLinkError>(
"Unsupported FDE pointer encoding " +
formatv("{0:x2}", FDEPointerEncoding) + " in CIE at " +
formatv("{0:x16}", CIESymbol.getAddress()));
CIEInfo.FDEPointerEncoding = FDEPointerEncoding;
break;
}
default:
llvm_unreachable("Invalid augmentation string field");
}
}
if (RecordReader.getOffset() - AugmentationDataStartOffset >
AugmentationDataLength)
return make_error<JITLinkError>("Read past the end of the augmentation "
"data while parsing fields");
assert(!PC.CIEInfos.count(CIESymbol.getAddress()) &&
"Multiple CIEs recorded at the same address?");
PC.CIEInfos[CIESymbol.getAddress()] = std::move(CIEInfo);
return Error::success();
}
Error EHFrameEdgeFixer::processFDE(ParseContext &PC, Block &B,
size_t RecordOffset, size_t RecordLength,
size_t CIEDeltaFieldOffset,
uint32_t CIEDelta,
BlockEdgeMap &BlockEdges) {
LLVM_DEBUG(dbgs() << " Record is FDE\n");
JITTargetAddress RecordAddress = B.getAddress() + RecordOffset;
auto RecordContent = B.getContent().slice(RecordOffset, RecordLength);
BinaryStreamReader RecordReader(
StringRef(RecordContent.data(), RecordContent.size()),
PC.G.getEndianness());
// Skip past the CIE delta field: we've already read this far.
RecordReader.setOffset(CIEDeltaFieldOffset + 4);
auto &FDESymbol =
PC.G.addAnonymousSymbol(B, RecordOffset, RecordLength, false, false);
CIEInformation *CIEInfo = nullptr;
{
// Process the CIE pointer field.
auto CIEEdgeItr = BlockEdges.find(RecordOffset + CIEDeltaFieldOffset);
JITTargetAddress CIEAddress =
RecordAddress + CIEDeltaFieldOffset - CIEDelta;
if (CIEEdgeItr == BlockEdges.end()) {
LLVM_DEBUG({
dbgs() << " Adding edge at "
<< formatv("{0:x16}", RecordAddress + CIEDeltaFieldOffset)
<< " to CIE at: " << formatv("{0:x16}", CIEAddress) << "\n";
});
if (auto CIEInfoOrErr = PC.findCIEInfo(CIEAddress))
CIEInfo = *CIEInfoOrErr;
else
return CIEInfoOrErr.takeError();
assert(CIEInfo->CIESymbol && "CIEInfo has no CIE symbol set");
B.addEdge(NegDelta32, RecordOffset + CIEDeltaFieldOffset,
*CIEInfo->CIESymbol, 0);
} else {
LLVM_DEBUG({
dbgs() << " Already has edge at "
<< formatv("{0:x16}", RecordAddress + CIEDeltaFieldOffset)
<< " to CIE at " << formatv("{0:x16}", CIEAddress) << "\n";
});
auto &EI = CIEEdgeItr->second;
if (EI.Addend)
return make_error<JITLinkError>(
"CIE edge at " +
formatv("{0:x16}", RecordAddress + CIEDeltaFieldOffset) +
" has non-zero addend");
if (auto CIEInfoOrErr = PC.findCIEInfo(EI.Target->getAddress()))
CIEInfo = *CIEInfoOrErr;
else
return CIEInfoOrErr.takeError();
}
}
{
// Process the PC-Begin field.
Block *PCBeginBlock = nullptr;
JITTargetAddress PCBeginFieldOffset = RecordReader.getOffset();
auto PCEdgeItr = BlockEdges.find(RecordOffset + PCBeginFieldOffset);
if (PCEdgeItr == BlockEdges.end()) {
auto PCBeginPtrInfo =
readEncodedPointer(CIEInfo->FDEPointerEncoding,
RecordAddress + PCBeginFieldOffset, RecordReader);
if (!PCBeginPtrInfo)
return PCBeginPtrInfo.takeError();
JITTargetAddress PCBegin = PCBeginPtrInfo->first;
Edge::Kind PCBeginEdgeKind = PCBeginPtrInfo->second;
LLVM_DEBUG({
dbgs() << " Adding edge at "
<< formatv("{0:x16}", RecordAddress + PCBeginFieldOffset)
<< " to PC at " << formatv("{0:x16}", PCBegin) << "\n";
});
auto PCBeginSym = getOrCreateSymbol(PC, PCBegin);
if (!PCBeginSym)
return PCBeginSym.takeError();
B.addEdge(PCBeginEdgeKind, RecordOffset + PCBeginFieldOffset, *PCBeginSym,
0);
PCBeginBlock = &PCBeginSym->getBlock();
} else {
auto &EI = PCEdgeItr->second;
LLVM_DEBUG({
dbgs() << " Already has edge at "
<< formatv("{0:x16}", RecordAddress + PCBeginFieldOffset)
<< " to PC at " << formatv("{0:x16}", EI.Target->getAddress());
if (EI.Addend)
dbgs() << " + " << formatv("{0:x16}", EI.Addend);
dbgs() << "\n";
});
// Make sure the existing edge points at a defined block.
if (!EI.Target->isDefined()) {
auto EdgeAddr = RecordAddress + PCBeginFieldOffset;
return make_error<JITLinkError>("FDE edge at " +
formatv("{0:x16}", EdgeAddr) +
" points at external block");
}
PCBeginBlock = &EI.Target->getBlock();
if (auto Err = RecordReader.skip(
getPointerEncodingDataSize(CIEInfo->FDEPointerEncoding)))
return Err;
}
// Add a keep-alive edge from the FDE target to the FDE to ensure that the
// FDE is kept alive if its target is.
assert(PCBeginBlock && "PC-begin block not recorded");
LLVM_DEBUG({
dbgs() << " Adding keep-alive edge from target at "
<< formatv("{0:x16}", PCBeginBlock->getAddress()) << " to FDE at "
<< formatv("{0:x16}", RecordAddress) << "\n";
});
PCBeginBlock->addEdge(Edge::KeepAlive, 0, FDESymbol, 0);
}
// Skip over the PC range size field.
if (auto Err = RecordReader.skip(
getPointerEncodingDataSize(CIEInfo->FDEPointerEncoding)))
return Err;
if (CIEInfo->FDEsHaveLSDAField) {
uint64_t AugmentationDataSize;
if (auto Err = RecordReader.readULEB128(AugmentationDataSize))
return Err;
JITTargetAddress LSDAFieldOffset = RecordReader.getOffset();
auto LSDAEdgeItr = BlockEdges.find(RecordOffset + LSDAFieldOffset);
if (LSDAEdgeItr == BlockEdges.end()) {
auto LSDAPointerInfo =
readEncodedPointer(CIEInfo->LSDAPointerEncoding,
RecordAddress + LSDAFieldOffset, RecordReader);
if (!LSDAPointerInfo)
return LSDAPointerInfo.takeError();
JITTargetAddress LSDA = LSDAPointerInfo->first;
Edge::Kind LSDAEdgeKind = LSDAPointerInfo->second;
auto LSDASym = getOrCreateSymbol(PC, LSDA);
if (!LSDASym)
return LSDASym.takeError();
LLVM_DEBUG({
dbgs() << " Adding edge at "
<< formatv("{0:x16}", RecordAddress + LSDAFieldOffset)
<< " to LSDA at " << formatv("{0:x16}", LSDA) << "\n";
});
B.addEdge(LSDAEdgeKind, RecordOffset + LSDAFieldOffset, *LSDASym, 0);
} else {
LLVM_DEBUG({
auto &EI = LSDAEdgeItr->second;
dbgs() << " Already has edge at "
<< formatv("{0:x16}", RecordAddress + LSDAFieldOffset)
<< " to LSDA at " << formatv("{0:x16}", EI.Target->getAddress());
if (EI.Addend)
dbgs() << " + " << formatv("{0:x16}", EI.Addend);
dbgs() << "\n";
});
if (auto Err = RecordReader.skip(AugmentationDataSize))
return Err;
}
} else {
LLVM_DEBUG(dbgs() << " Record does not have LSDA field.\n");
}
return Error::success();
}
Expected<EHFrameEdgeFixer::AugmentationInfo>
EHFrameEdgeFixer::parseAugmentationString(BinaryStreamReader &RecordReader) {
AugmentationInfo AugInfo;
uint8_t NextChar;
uint8_t *NextField = &AugInfo.Fields[0];
if (auto Err = RecordReader.readInteger(NextChar))
return std::move(Err);
while (NextChar != 0) {
switch (NextChar) {
case 'z':
AugInfo.AugmentationDataPresent = true;
break;
case 'e':
if (auto Err = RecordReader.readInteger(NextChar))
return std::move(Err);
if (NextChar != 'h')
return make_error<JITLinkError>("Unrecognized substring e" +
Twine(NextChar) +
" in augmentation string");
AugInfo.EHDataFieldPresent = true;
break;
case 'L':
case 'P':
case 'R':
*NextField++ = NextChar;
break;
default:
return make_error<JITLinkError>("Unrecognized character " +
Twine(NextChar) +
" in augmentation string");
}
if (auto Err = RecordReader.readInteger(NextChar))
return std::move(Err);
}
return std::move(AugInfo);
}
bool EHFrameEdgeFixer::isSupportedPointerEncoding(uint8_t PointerEncoding) {
using namespace dwarf;
// We only support PC-rel for now.
if ((PointerEncoding & 0x70) != DW_EH_PE_pcrel)
return false;
// readEncodedPointer does not handle indirect.
if (PointerEncoding & DW_EH_PE_indirect)
return false;
// Supported datatypes.
switch (PointerEncoding & 0xf) {
case DW_EH_PE_absptr:
case DW_EH_PE_udata4:
case DW_EH_PE_udata8:
case DW_EH_PE_sdata4:
case DW_EH_PE_sdata8:
return true;
}
return false;
}
unsigned EHFrameEdgeFixer::getPointerEncodingDataSize(uint8_t PointerEncoding) {
using namespace dwarf;
assert(isSupportedPointerEncoding(PointerEncoding) &&
"Unsupported pointer encoding");
switch (PointerEncoding & 0xf) {
case DW_EH_PE_absptr:
return PointerSize;
case DW_EH_PE_udata4:
case DW_EH_PE_sdata4:
return 4;
case DW_EH_PE_udata8:
case DW_EH_PE_sdata8:
return 8;
default:
llvm_unreachable("Unsupported encoding");
}
}
Expected<std::pair<JITTargetAddress, Edge::Kind>>
EHFrameEdgeFixer::readEncodedPointer(uint8_t PointerEncoding,
JITTargetAddress PointerFieldAddress,
BinaryStreamReader &RecordReader) {
static_assert(sizeof(JITTargetAddress) == sizeof(uint64_t),
"Result must be able to hold a uint64_t");
assert(isSupportedPointerEncoding(PointerEncoding) &&
"Unsupported pointer encoding");
using namespace dwarf;
// Isolate data type, remap absptr to udata4 or udata8. This relies on us
// having verified that the graph uses 32-bit or 64-bit pointers only at the
// start of this pass.
uint8_t EffectiveType = PointerEncoding & 0xf;
if (EffectiveType == DW_EH_PE_absptr)
EffectiveType = (PointerSize == 8) ? DW_EH_PE_udata8 : DW_EH_PE_udata4;
JITTargetAddress Addr;
Edge::Kind PointerEdgeKind;
switch (EffectiveType) {
case DW_EH_PE_udata4: {
uint32_t Val;
if (auto Err = RecordReader.readInteger(Val))
return std::move(Err);
Addr = PointerFieldAddress + Val;
PointerEdgeKind = Delta32;
break;
}
case DW_EH_PE_udata8: {
uint64_t Val;
if (auto Err = RecordReader.readInteger(Val))
return std::move(Err);
Addr = PointerFieldAddress + Val;
PointerEdgeKind = Delta64;
break;
}
case DW_EH_PE_sdata4: {
int32_t Val;
if (auto Err = RecordReader.readInteger(Val))
return std::move(Err);
Addr = PointerFieldAddress + Val;
PointerEdgeKind = Delta32;
break;
}
case DW_EH_PE_sdata8: {
int64_t Val;
if (auto Err = RecordReader.readInteger(Val))
return std::move(Err);
Addr = PointerFieldAddress + Val;
PointerEdgeKind = Delta64;
break;
}
}
if (PointerEdgeKind == Edge::Invalid)
return make_error<JITLinkError>(
"Unspported edge kind for encoded pointer at " +
formatv("{0:x}", PointerFieldAddress));
return std::make_pair(Addr, Delta64);
}
Expected<Symbol &> EHFrameEdgeFixer::getOrCreateSymbol(ParseContext &PC,
JITTargetAddress Addr) {
Symbol *CanonicalSym = nullptr;
auto UpdateCanonicalSym = [&](Symbol *Sym) {
if (!CanonicalSym || Sym->getLinkage() < CanonicalSym->getLinkage() ||
Sym->getScope() < CanonicalSym->getScope() ||
(Sym->hasName() && !CanonicalSym->hasName()) ||
Sym->getName() < CanonicalSym->getName())
CanonicalSym = Sym;
};
if (auto *SymbolsAtAddr = PC.AddrToSyms.getSymbolsAt(Addr))
for (auto *Sym : *SymbolsAtAddr)
UpdateCanonicalSym(Sym);
// If we found an existing symbol at the given address then use it.
if (CanonicalSym)
return *CanonicalSym;
// Otherwise search for a block covering the address and create a new symbol.
auto *B = PC.AddrToBlock.getBlockCovering(Addr);
if (!B)
return make_error<JITLinkError>("No symbol or block covering address " +
formatv("{0:x16}", Addr));
return PC.G.addAnonymousSymbol(*B, Addr - B->getAddress(), 0, false, false);
}
char EHFrameNullTerminator::NullTerminatorBlockContent[4] = {0, 0, 0, 0};
EHFrameNullTerminator::EHFrameNullTerminator(StringRef EHFrameSectionName)
: EHFrameSectionName(EHFrameSectionName) {}
Error EHFrameNullTerminator::operator()(LinkGraph &G) {
auto *EHFrame = G.findSectionByName(EHFrameSectionName);
if (!EHFrame)
return Error::success();
LLVM_DEBUG({
dbgs() << "EHFrameNullTerminator adding null terminator to "
<< EHFrameSectionName << "\n";
});
auto &NullTerminatorBlock = G.createContentBlock(
*EHFrame, NullTerminatorBlockContent, 0xfffffffffffffffc, 1, 0);
G.addAnonymousSymbol(NullTerminatorBlock, 0, 4, false, true);
return Error::success();
}
EHFrameRegistrar::~EHFrameRegistrar() {}
Error InProcessEHFrameRegistrar::registerEHFrames(
JITTargetAddress EHFrameSectionAddr, size_t EHFrameSectionSize) {
return orc::registerEHFrameSection(
jitTargetAddressToPointer<void *>(EHFrameSectionAddr),
EHFrameSectionSize);
}
Error InProcessEHFrameRegistrar::deregisterEHFrames(
JITTargetAddress EHFrameSectionAddr, size_t EHFrameSectionSize) {
return orc::deregisterEHFrameSection(
jitTargetAddressToPointer<void *>(EHFrameSectionAddr),
EHFrameSectionSize);
}
LinkGraphPassFunction
createEHFrameRecorderPass(const Triple &TT,
StoreFrameRangeFunction StoreRangeAddress) {
const char *EHFrameSectionName = nullptr;
if (TT.getObjectFormat() == Triple::MachO)
EHFrameSectionName = "__TEXT,__eh_frame";
else
EHFrameSectionName = ".eh_frame";
auto RecordEHFrame =
[EHFrameSectionName,
StoreFrameRange = std::move(StoreRangeAddress)](LinkGraph &G) -> Error {
// Search for a non-empty eh-frame and record the address of the first
// symbol in it.
JITTargetAddress Addr = 0;
size_t Size = 0;
if (auto *S = G.findSectionByName(EHFrameSectionName)) {
auto R = SectionRange(*S);
Addr = R.getStart();
Size = R.getSize();
}
if (Addr == 0 && Size != 0)
return make_error<JITLinkError>(
StringRef(EHFrameSectionName) +
" section can not have zero address with non-zero size");
StoreFrameRange(Addr, Size);
return Error::success();
};
return RecordEHFrame;
}
} // end namespace jitlink
} // end namespace llvm
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