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Ignore functions referencing symbol at 0x0.

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Summary:
Binary code could be weird. It could include calls to address 0 and
reference data at 0 (e.g. with lea on x86). LLVM JIT fatals
while resolving relocations against symbols at address 0x0. For now
we will stop emitting such code, i.e. we'll skip functions.

(cherry picked from FBD28109837)
This commit is contained in:
Maksim Panchenko 2015-12-16 17:56:49 -08:00
parent f7d7a85a24
commit e2fcb371a8
1 changed files with 13 additions and 3 deletions
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16
bolt/BinaryFunction.cpp
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@ -75,6 +75,7 @@ void BinaryFunction::print(raw_ostream &OS, std::string Annotation,
<< "\n Offset : 0x" << Twine::utohexstr(FileOffset)
<< "\n Section : " << SectionName
<< "\n Orc Section : " << getCodeSectionName()
<< "\n LSDA : 0x" << Twine::utohexstr(getLSDAAddress())
<< "\n IsSimple : " << IsSimple
<< "\n IsSplit : " << IsSplit
<< "\n BB Count : " << BasicBlocksLayout.size();
@ -289,7 +290,7 @@ bool BinaryFunction::disassemble(ArrayRef<uint8_t> FunctionData) {
Labels[0] = Ctx->createTempSymbol("BB0", false);
auto handleRIPOperand =
[this](MCInst &Instruction, uint64_t Address, uint64_t Size) -> bool {
[&](MCInst &Instruction, uint64_t Address, uint64_t Size) -> bool {
uint64_t TargetAddress{0};
MCSymbol *TargetSymbol{nullptr};
if (!BC.MIA->evaluateRIPOperand(Instruction, Address, Size,
@ -302,6 +303,11 @@ bool BinaryFunction::disassemble(ArrayRef<uint8_t> FunctionData) {
return false;
}
// FIXME: check that the address is in data, not in code.
if (TargetAddress == 0) {
errs() << "FLO-WARNING: rip-relative operand is zero in function "
<< getName() << ". Ignoring function.\n";
return false;
}
TargetSymbol = BC.getOrCreateGlobalSymbol(TargetAddress, "DATAat");
BC.MIA->replaceRIPOperandDisp(
Instruction, MCOperand::createExpr(MCSymbolRefExpr::create(
@ -392,8 +398,12 @@ bool BinaryFunction::disassemble(ArrayRef<uint8_t> FunctionData) {
TargetSymbol = BC.getOrCreateGlobalSymbol(InstructionTarget,
"FUNCat");
if (InstructionTarget == 0) {
errs() << "FLO-WARNING: Function \":" << getName()
<< "\" has call to address zero. Ignoring it.\n";
// We actually see calls to address 0 because of the weak symbols
// from the libraries. In reality more often than not it is
// unreachable code, but we don't know it and have to emit calls
// to 0 which make LLVM JIT unhappy.
errs() << "FLO-WARNING: Function " << getName()
<< " has a call to address zero. Ignoring function.\n";
IsSimple = false;
}
}