| //===--- ImageInspectionELF.cpp - ELF image inspection --------------------===// |
| // |
| // This source file is part of the Swift.org open source project |
| // |
| // Copyright (c) 2014 - 2017 Apple Inc. and the Swift project authors |
| // Licensed under Apache License v2.0 with Runtime Library Exception |
| // |
| // See https://swift.org/LICENSE.txt for license information |
| // See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors |
| // |
| //===----------------------------------------------------------------------===// |
| /// |
| /// \file |
| /// |
| /// This file includes routines that interact with ld*.so on ELF-based platforms |
| /// to extract runtime metadata embedded in dynamically linked ELF images |
| /// generated by the Swift compiler. |
| /// |
| //===----------------------------------------------------------------------===// |
| |
| #if (defined(__ELF__) || defined(__ANDROID__)) && !defined(__HAIKU__) |
| |
| #include "ImageInspection.h" |
| #include "swift/Runtime/Debug.h" |
| #include <dlfcn.h> |
| #include <elf.h> |
| #include <link.h> |
| #include <string.h> |
| |
| #if defined(__ANDROID__) |
| #include "llvm/ADT/StringRef.h" |
| #endif |
| |
| using namespace swift; |
| |
| /// The symbol name in the image that identifies the beginning of the |
| /// protocol conformances table. |
| static const char ProtocolConformancesSymbol[] = |
| ".swift2_protocol_conformances_start"; |
| /// The symbol name in the image that identifies the beginning of the |
| /// type metadata record table. |
| static const char TypeMetadataRecordsSymbol[] = |
| ".swift2_type_metadata_start"; |
| |
| /// Context arguments passed down from dl_iterate_phdr to its callback. |
| struct InspectArgs { |
| /// Symbol name to look up. |
| const char *symbolName; |
| /// Callback function to invoke with the metadata block. |
| void (*addBlock)(const void *start, uintptr_t size); |
| /// Set to true when initialize*Lookup() is called. |
| bool didInitializeLookup; |
| }; |
| |
| static InspectArgs ProtocolConformanceArgs = { |
| ProtocolConformancesSymbol, |
| addImageProtocolConformanceBlockCallback, |
| false |
| }; |
| |
| static InspectArgs TypeMetadataRecordArgs = { |
| TypeMetadataRecordsSymbol, |
| addImageTypeMetadataRecordBlockCallback, |
| false |
| }; |
| |
| |
| // Extract the section information for a named section in an image. imageName |
| // can be nullptr to specify the main executable. |
| static SectionInfo getSectionInfo(const char *imageName, |
| const char *sectionName) { |
| SectionInfo sectionInfo = { 0, nullptr }; |
| void *handle = dlopen(imageName, RTLD_LAZY | RTLD_NOLOAD); |
| if (!handle) { |
| #ifdef __ANDROID__ |
| llvm::StringRef imagePath = llvm::StringRef(imageName); |
| if (imagePath.startswith("/system/lib") || |
| (imageName && !imagePath.endswith(".so"))) { |
| return sectionInfo; |
| } |
| #endif |
| fatalError(/* flags = */ 0, "dlopen() failed on `%s': %s", imageName, |
| dlerror()); |
| } |
| void *symbol = dlsym(handle, sectionName); |
| if (symbol) { |
| // Extract the size of the section data from the head of the section. |
| const char *section = reinterpret_cast<const char *>(symbol); |
| memcpy(§ionInfo.size, section, sizeof(uint64_t)); |
| sectionInfo.data = section + sizeof(uint64_t); |
| } |
| dlclose(handle); |
| return sectionInfo; |
| } |
| |
| static int iteratePHDRCallback(struct dl_phdr_info *info, |
| size_t size, void *data) { |
| InspectArgs *inspectArgs = reinterpret_cast<InspectArgs *>(data); |
| const char *fname = info->dlpi_name; |
| |
| // While dl_iterate_phdr() is in progress it holds a lock to prevent other |
| // images being loaded. The initialize flag is set here inside the callback so |
| // that addNewDSOImage() sees a consistent state. If it was set outside the |
| // dl_iterate_phdr() call then it could result in images being missed or |
| // added twice. |
| inspectArgs->didInitializeLookup = true; |
| |
| if (fname == nullptr || fname[0] == '\0') { |
| // The filename may be null for both the dynamic loader and main executable. |
| // So ignore null image name here and explicitly add the main executable |
| // in initialize*Lookup() to avoid adding the data twice. |
| return 0; |
| } |
| |
| SectionInfo block = getSectionInfo(fname, inspectArgs->symbolName); |
| if (block.size > 0) { |
| inspectArgs->addBlock(block.data, block.size); |
| } |
| return 0; |
| } |
| |
| // Add the section information in an image specified by an address in that |
| // image. |
| static void addBlockInImage(const InspectArgs *inspectArgs, const void *addr) { |
| const char *fname = nullptr; |
| if (addr) { |
| Dl_info info; |
| if (dladdr(addr, &info) == 0 || info.dli_fname == nullptr) { |
| return; |
| } |
| fname = info.dli_fname; |
| } |
| SectionInfo block = getSectionInfo(fname, inspectArgs->symbolName); |
| if (block.size > 0) { |
| inspectArgs->addBlock(block.data, block.size); |
| } |
| } |
| |
| static void initializeSectionLookup(InspectArgs *inspectArgs) { |
| // Add section data in the main executable. |
| addBlockInImage(inspectArgs, nullptr); |
| // Search the loaded dls. This only searches the already |
| // loaded ones. Any images loaded after this are processed by |
| // addNewDSOImage() below. |
| dl_iterate_phdr(iteratePHDRCallback, reinterpret_cast<void *>(inspectArgs)); |
| } |
| |
| void swift::initializeProtocolConformanceLookup() { |
| initializeSectionLookup(&ProtocolConformanceArgs); |
| } |
| |
| void swift::initializeTypeMetadataRecordLookup() { |
| initializeSectionLookup(&TypeMetadataRecordArgs); |
| } |
| |
| // As ELF images are loaded, ImageInspectionInit:sectionDataInit() will call |
| // addNewDSOImage() with an address in the image that can later be used via |
| // dladdr() to dlopen() the image after the appropriate initialize*Lookup() |
| // function has been called. |
| SWIFT_RUNTIME_EXPORT |
| void swift_addNewDSOImage(const void *addr) { |
| if (ProtocolConformanceArgs.didInitializeLookup) { |
| addBlockInImage(&ProtocolConformanceArgs, addr); |
| } |
| |
| if (TypeMetadataRecordArgs.didInitializeLookup) { |
| addBlockInImage(&TypeMetadataRecordArgs, addr); |
| } |
| } |
| |
| int swift::lookupSymbol(const void *address, SymbolInfo *info) { |
| Dl_info dlinfo; |
| if (dladdr(address, &dlinfo) == 0) { |
| return 0; |
| } |
| |
| info->fileName = dlinfo.dli_fname; |
| info->baseAddress = dlinfo.dli_fbase; |
| info->symbolName = dlinfo.dli_sname; |
| info->symbolAddress = dlinfo.dli_saddr; |
| return 1; |
| } |
| |
| #endif // defined(__ELF__) || defined(__ANDROID__) |