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[BOLT] Add support for IFUNC 

Summary:
Relocation value verification was failing for IFUNC as the real value
used for relocation wasn't the symbol value, but a corresponding PLT
entry.

Relax the verification and skip any symbols of ST_Other type.

(cherry picked from FBD9123741)
This commit is contained in:
Maksim Panchenko 2018-07-30 10:29:47 -07:00
parent df94786119
commit 39f6fcc947
1 changed files with 17 additions and 60 deletions
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77
bolt/src/RewriteInstance.cpp
View File

@ -1859,7 +1859,7 @@ bool RewriteInstance::analyzeRelocation(const RelocationRef &Rel,
auto SymbolIter = Rel.getSymbol();
assert(SymbolIter != InputFile->symbol_end() &&
"relocation symbol must exist");
auto Symbol = *SymbolIter;
const auto &Symbol = *SymbolIter;
SymbolName = cantFail(Symbol.getName());
SymbolAddress = cantFail(Symbol.getAddress());
Addend = getRelocationAddend(InputFile, Rel);
@ -1920,67 +1920,24 @@ bool RewriteInstance::analyzeRelocation(const RelocationRef &Rel,
}
}
if (!IsPCRelative && Addend != 0 && IsFromCode && !SymbolIsSection) {
// TODO: RefSection should be the same as **(Symbol.getSection()).
auto RefSection = BC->getSectionForAddress(SymbolAddress);
if (RefSection && RefSection->isText()) {
if (opts::Verbosity > 1) {
SmallString<16> TypeName;
Rel.getTypeName(TypeName);
errs() << "BOLT-WARNING: detected absolute reference from code into "
<< "a middle of a function:\n"
<< " offset = 0x" << Twine::utohexstr(Rel.getOffset())
<< "; type = " << Rel.getType()
<< "; type name = " << TypeName
<< "; value = 0x" << Twine::utohexstr(ExtractedValue)
<< "; symbol = " << SymbolName
<< "; symbol address = 0x" << Twine::utohexstr(SymbolAddress)
<< "; symbol section = " << RefSection->getName()
<< "; addend = 0x" << Twine::utohexstr(Addend)
<< "; address = 0x" << Twine::utohexstr(SymbolAddress + Addend)
<< '\n';
}
assert(truncateToSize(ExtractedValue, RelSize) ==
truncateToSize(SymbolAddress + Addend, RelSize) &&
"value mismatch");
}
}
auto verifyExtractedValue = [&]() {
if (IsAArch64)
return true;
DEBUG(
if (!Relocation::isTLS(Rel.getType()) &&
SymbolName != "__hot_start" &&
SymbolName != "__hot_end" &&
truncateToSize(ExtractedValue, RelSize) !=
truncateToSize(SymbolAddress + Addend - PCRelOffset, RelSize)) {
auto Section = cantFail(Symbol.getSection());
SmallString<16> TypeName;
Rel.getTypeName(TypeName);
dbgs() << "BOLT-DEBUG: Mismatch between extracted value and relocation "
<< "data:\n"
<< "BOLT-DEBUG: offset = 0x"
<< Twine::utohexstr(Rel.getOffset())
<< "; type = " << Rel.getType()
<< "; type name = " << TypeName
<< "; value = 0x" << Twine::utohexstr(ExtractedValue)
<< "; symbol = " << SymbolName
<< "; symbol type = " << cantFail(Symbol.getType())
<< "; symbol address = 0x" << Twine::utohexstr(SymbolAddress)
<< "; orig symbol address = 0x"
<< Twine::utohexstr(cantFail(Symbol.getAddress()))
<< "; symbol section = " << getSectionName(*Section)
<< "; addend = 0x" << Twine::utohexstr(Addend)
<< "; original addend = 0x"
<< Twine::utohexstr(getRelocationAddend(InputFile, Rel))
<< '\n';
});
if (SymbolName == "__hot_start" || SymbolName == "__hot_end")
return true;
assert((IsAArch64 ||
Relocation::isTLS(Rel.getType()) ||
SymbolName == "__hot_start" ||
SymbolName == "__hot_end" ||
truncateToSize(ExtractedValue, RelSize) ==
truncateToSize(SymbolAddress + Addend - PCRelOffset, RelSize)) &&
"extracted relocation value should match relocation components");
if (Relocation::isTLS(Rel.getType()))
return true;
if (cantFail(Symbol.getType()) == SymbolRef::ST_Other)
return true;
return truncateToSize(ExtractedValue, RelSize) ==
truncateToSize(SymbolAddress + Addend - PCRelOffset, RelSize);
};
assert(verifyExtractedValue() && "mismatched extracted relocation value");
return true;
}