[llvm] r241383 - [RuntimeDyld] Skip relocations for external symbols with 64-bit address ~0ULL.
Lang Hames
lhames at gmail.com
Sun Jul 5 11:50:35 PDT 2015
Good point. In r241408 I've added a comment to SymbolResolver::findSymbol
in RuntimeDyld.h documenting the change.
Cheers,
Lang.
On Fri, Jul 3, 2015 at 9:47 PM, Philip Reames <listmail at philipreames.com>
wrote:
> On 07/03/2015 06:35 PM, Lang Hames wrote:
>
>> Author: lhames
>> Date: Fri Jul 3 20:35:26 2015
>> New Revision: 241383
>>
>> URL: http://llvm.org/viewvc/llvm-project?rev=241383&view=rev
>> Log:
>> [RuntimeDyld] Skip relocations for external symbols with 64-bit address
>> ~0ULL.
>>
>> Requested by Eugene Rozenfeld of the LLILC team, this feature allows JIT
>> clients to skip relocations for selected external symbols by returning
>> ~0ULL
>> from their symbol resolver. If this value is returned for a given symbol,
>> RuntimeDyld will skip all relocations for that symbol. The client will be
>> responsible for applying the skipped relocations manually before the code
>> is executed.
>>
> This seems like it's worth documenting somewhere. Possibly on the comment
> for getSymbolAddress on MCJITMemoryManager?
>
>
>>
>> Modified:
>> llvm/trunk/lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp
>> llvm/trunk/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldChecker.cpp
>>
>> llvm/trunk/test/ExecutionEngine/RuntimeDyld/X86/MachO_x86-64_PIC_relocations.s
>> llvm/trunk/tools/llvm-rtdyld/llvm-rtdyld.cpp
>>
>> Modified: llvm/trunk/lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp
>> URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp?rev=241383&r1=241382&r2=241383&view=diff
>>
>> ==============================================================================
>> --- llvm/trunk/lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp (original)
>> +++ llvm/trunk/lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp Fri Jul 3
>> 20:35:26 2015
>> @@ -815,12 +815,16 @@ void RuntimeDyldImpl::resolveExternalSym
>> report_fatal_error("Program used external function '" + Name +
>> "' which could not be resolved!");
>> - DEBUG(dbgs() << "Resolving relocations Name: " << Name << "\t"
>> - << format("0x%lx", Addr) << "\n");
>> - // This list may have been updated when we called
>> getSymbolAddress, so
>> - // don't change this code to get the list earlier.
>> - RelocationList &Relocs = i->second;
>> - resolveRelocationList(Relocs, Addr);
>> + // If Resolver returned UINT64_MAX, the client wants to handle
>> this symbol
>> + // manually and we shouldn't resolve its relocations.
>> + if (Addr != UINT64_MAX) {
>> + DEBUG(dbgs() << "Resolving relocations Name: " << Name << "\t"
>> + << format("0x%lx", Addr) << "\n");
>> + // This list may have been updated when we called
>> getSymbolAddress, so
>> + // don't change this code to get the list earlier.
>> + RelocationList &Relocs = i->second;
>> + resolveRelocationList(Relocs, Addr);
>> + }
>> }
>> ExternalSymbolRelocations.erase(i);
>>
>> Modified:
>> llvm/trunk/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldChecker.cpp
>> URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldChecker.cpp?rev=241383&r1=241382&r2=241383&view=diff
>>
>> ==============================================================================
>> --- llvm/trunk/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldChecker.cpp
>> (original)
>> +++ llvm/trunk/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldChecker.cpp Fri
>> Jul 3 20:35:26 2015
>> @@ -727,7 +727,9 @@ bool RuntimeDyldCheckerImpl::checkAllRul
>> }
>> bool RuntimeDyldCheckerImpl::isSymbolValid(StringRef Symbol) const {
>> - return getRTDyld().getSymbolLocalAddress(Symbol) != nullptr;
>> + if (getRTDyld().getSymbolLocalAddress(Symbol))
>> + return true;
>> + return !!getRTDyld().Resolver.findSymbol(Symbol);
>> }
>> uint64_t RuntimeDyldCheckerImpl::getSymbolLocalAddr(StringRef Symbol)
>> const {
>>
>> Modified:
>> llvm/trunk/test/ExecutionEngine/RuntimeDyld/X86/MachO_x86-64_PIC_relocations.s
>> URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/ExecutionEngine/RuntimeDyld/X86/MachO_x86-64_PIC_relocations.s?rev=241383&r1=241382&r2=241383&view=diff
>>
>> ==============================================================================
>> ---
>> llvm/trunk/test/ExecutionEngine/RuntimeDyld/X86/MachO_x86-64_PIC_relocations.s
>> (original)
>> +++
>> llvm/trunk/test/ExecutionEngine/RuntimeDyld/X86/MachO_x86-64_PIC_relocations.s
>> Fri Jul 3 20:35:26 2015
>> @@ -1,5 +1,5 @@
>> # RUN: llvm-mc -triple=x86_64-apple-macosx10.9 -relocation-model=pic
>> -filetype=obj -o %T/test_x86-64.o %s
>> -# RUN: llvm-rtdyld -triple=x86_64-apple-macosx10.9 -verify -check=%s
>> %/T/test_x86-64.o
>> +# RUN: llvm-rtdyld -triple=x86_64-apple-macosx10.9 -dummy-extern
>> ds1=0xfffffffffffffffe -dummy-extern ds2=0xffffffffffffffff -verify
>> -check=%s %/T/test_x86-64.o
>> .section __TEXT,__text,regular,pure_instructions
>> .globl foo
>> @@ -46,4 +46,15 @@ eh_frame_test:
>> x:
>> .long 5
>> +# Test dummy-extern relocation.
>> +# rtdyld-check: *{8}z1 = ds1
>> +z1:
>> + .quad ds1
>> +
>> +# Test external-symbol relocation bypass: symbols with addr
>> 0xffffffffffffffff
>> +# don't have their relocations applied.
>> +# rtdyld-check: *{8}z2 = 0
>> +z2:
>> + .quad ds2
>> +
>> .subsections_via_symbols
>>
>> Modified: llvm/trunk/tools/llvm-rtdyld/llvm-rtdyld.cpp
>> URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/tools/llvm-rtdyld/llvm-rtdyld.cpp?rev=241383&r1=241382&r2=241383&view=diff
>>
>> ==============================================================================
>> --- llvm/trunk/tools/llvm-rtdyld/llvm-rtdyld.cpp (original)
>> +++ llvm/trunk/tools/llvm-rtdyld/llvm-rtdyld.cpp Fri Jul 3 20:35:26 2015
>> @@ -115,8 +115,17 @@ TargetSectionSep("target-section-sep",
>> static cl::list<std::string>
>> SpecificSectionMappings("map-section",
>> - cl::desc("Map a section to a specific address."),
>> - cl::ZeroOrMore);
>> + cl::desc("For -verify only: Map a section to a "
>> + "specific address."),
>> + cl::ZeroOrMore,
>> + cl::Hidden);
>> +
>> +static cl::list<std::string>
>> +DummySymbolMappings("dummy-extern",
>> + cl::desc("For -verify only: Inject a symbol into the
>> extern "
>> + "symbol table."),
>> + cl::ZeroOrMore,
>> + cl::Hidden);
>> /* *** */
>> @@ -147,10 +156,25 @@ public:
>> // relocations) will get to the data cache but not to the instruction
>> cache.
>> virtual void invalidateInstructionCache();
>> + void addDummySymbol(const std::string &Name, uint64_t Addr) {
>> + DummyExterns[Name] = Addr;
>> + }
>> +
>> + RuntimeDyld::SymbolInfo findSymbol(const std::string &Name) override {
>> + auto I = DummyExterns.find(Name);
>> +
>> + if (I != DummyExterns.end())
>> + return RuntimeDyld::SymbolInfo(I->second,
>> JITSymbolFlags::Exported);
>> +
>> + return RTDyldMemoryManager::findSymbol(Name);
>> + }
>> +
>> void registerEHFrames(uint8_t *Addr, uint64_t LoadAddr,
>> size_t Size) override {}
>> void deregisterEHFrames(uint8_t *Addr, uint64_t LoadAddr,
>> size_t Size) override {}
>> +private:
>> + std::map<std::string, uint64_t> DummyExterns;
>> };
>> uint8_t *TrivialMemoryManager::allocateCodeSection(uintptr_t Size,
>> @@ -401,7 +425,7 @@ applySpecificSectionMappings(RuntimeDyld
>> for (StringRef Mapping : SpecificSectionMappings) {
>> size_t EqualsIdx = Mapping.find_first_of("=");
>> - StringRef SectionIDStr = Mapping.substr(0, EqualsIdx);
>> + std::string SectionIDStr = Mapping.substr(0, EqualsIdx);
>> size_t ComaIdx = Mapping.find_first_of(",");
>> if (ComaIdx == StringRef::npos) {
>> @@ -410,8 +434,8 @@ applySpecificSectionMappings(RuntimeDyld
>> exit(1);
>> }
>> - StringRef FileName = SectionIDStr.substr(0, ComaIdx);
>> - StringRef SectionName = SectionIDStr.substr(ComaIdx + 1);
>> + std::string FileName = SectionIDStr.substr(0, ComaIdx);
>> + std::string SectionName = SectionIDStr.substr(ComaIdx + 1);
>> uint64_t OldAddrInt;
>> std::string ErrorMsg;
>> @@ -425,11 +449,11 @@ applySpecificSectionMappings(RuntimeDyld
>> void* OldAddr =
>> reinterpret_cast<void*>(static_cast<uintptr_t>(OldAddrInt));
>> - StringRef NewAddrStr = Mapping.substr(EqualsIdx + 1);
>> + std::string NewAddrStr = Mapping.substr(EqualsIdx + 1);
>> uint64_t NewAddr;
>> - if (NewAddrStr.getAsInteger(0, NewAddr)) {
>> - errs() << "Invalid section address in mapping: " << Mapping <<
>> "\n";
>> + if (StringRef(NewAddrStr).getAsInteger(0, NewAddr)) {
>> + errs() << "Invalid section address in mapping '" << Mapping <<
>> "'.\n";
>> exit(1);
>> }
>> @@ -451,9 +475,9 @@ applySpecificSectionMappings(RuntimeDyld
>> // Defaults to zero. Set to something big
>> // (e.g. 1 << 32) to stress-test stubs,
>> GOTs, etc.
>> //
>> -static void remapSections(const llvm::Triple &TargetTriple,
>> - const TrivialMemoryManager &MemMgr,
>> - RuntimeDyldChecker &Checker) {
>> +static void remapSectionsAndSymbols(const llvm::Triple &TargetTriple,
>> + TrivialMemoryManager &MemMgr,
>> + RuntimeDyldChecker &Checker) {
>> // Set up a work list (section addr/size pairs).
>> typedef std::list<std::pair<void*, uint64_t>> WorklistT;
>> @@ -516,6 +540,27 @@ static void remapSections(const llvm::Tr
>> Checker.getRTDyld().mapSectionAddress(CurEntry.first,
>> NextSectionAddr);
>> }
>> + // Add dummy symbols to the memory manager.
>> + for (const auto &Mapping : DummySymbolMappings) {
>> + size_t EqualsIdx = Mapping.find_first_of("=");
>> +
>> + if (EqualsIdx == StringRef::npos) {
>> + errs() << "Invalid dummy symbol specification '" << Mapping
>> + << "'. Should be '<symbol name>=<addr>'\n";
>> + exit(1);
>> + }
>> +
>> + std::string Symbol = Mapping.substr(0, EqualsIdx);
>> + std::string AddrStr = Mapping.substr(EqualsIdx + 1);
>> +
>> + uint64_t Addr;
>> + if (StringRef(AddrStr).getAsInteger(0, Addr)) {
>> + errs() << "Invalid symbol mapping '" << Mapping << "'.\n";
>> + exit(1);
>> + }
>> +
>> + MemMgr.addDummySymbol(Symbol, Addr);
>> + }
>> }
>> // Load and link the objects specified on the command line, but do
>> not execute
>> @@ -604,8 +649,9 @@ static int linkAndVerify() {
>> }
>> }
>> - // Re-map the section addresses into the phony target address space.
>> - remapSections(TheTriple, MemMgr, Checker);
>> + // Re-map the section addresses into the phony target address space
>> and add
>> + // dummy symbols.
>> + remapSectionsAndSymbols(TheTriple, MemMgr, Checker);
>> // Resolve all the relocations we can.
>> Dyld.resolveRelocations();
>>
>>
>> _______________________________________________
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>> llvm-commits at cs.uiuc.edu
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>>
>
>
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