+ // don't need to do any coalescing if only one image has overrides, or all have already been done
+ if ( (countOfImagesWithWeakDefinitionsNotInSharedCache > 0) && (countNotYetWeakBound > 0) ) {
+ if (!context.weakDefMapInitialized) {
+ // Initialize the weak def map as the link context doesn't run static initializers
+ new (&context.weakDefMap) dyld3::Map<const char*, std::pair<const ImageLoader*, uintptr_t>, ImageLoader::HashCString, ImageLoader::EqualCString>();
+ context.weakDefMapInitialized = true;
+ }
+#if __MAC_OS_X_VERSION_MIN_REQUIRED
+ // only do alternate algorithm for dlopen(). Use traditional algorithm for launch
+ if ( !context.linkingMainExecutable ) {
+ // Don't take the memory hit of weak defs on the launch path until we hit a dlopen with more weak symbols to bind
+ if (!context.weakDefMapProcessedLaunchDefs) {
+ context.weakDefMapProcessedLaunchDefs = true;
+
+ // Walk the nlist for all binaries from launch and fill in the map with any other weak defs
+ for (int i=0; i < count; ++i) {
+ const ImageLoader* image = imagesNeedingCoalescing[i];
+ // skip images without defs. We've processed launch time refs already
+ if ( !image->hasCoalescedExports() )
+ continue;
+ // Only process binaries which have had their weak symbols bound, ie, not the new ones we are processing now
+ // from this dlopen
+ if ( !image->weakSymbolsBound(imageIndexes[i]) )
+ continue;
+
+ Diagnostics diag;
+ const dyld3::MachOAnalyzer* ma = (const dyld3::MachOAnalyzer*)image->machHeader();
+ ma->forEachWeakDef(diag, ^(const char *symbolName, uintptr_t imageOffset, bool isFromExportTrie) {
+ uintptr_t targetAddr = (uintptr_t)ma + imageOffset;
+ if ( isFromExportTrie ) {
+ // Avoid duplicating the string if we already have the symbol name
+ if ( context.weakDefMap.find(symbolName) != context.weakDefMap.end() )
+ return;
+ symbolName = strdup(symbolName);
+ }
+ context.weakDefMap.insert({ symbolName, { image, targetAddr } });
+ });
+ }
+ }
+
+ // Walk the nlist for all binaries in dlopen and fill in the map with any other weak defs
+ for (int i=0; i < count; ++i) {
+ const ImageLoader* image = imagesNeedingCoalescing[i];
+ if ( image->weakSymbolsBound(imageIndexes[i]) )
+ continue;
+ // skip images without defs. We'll process refs later
+ if ( !image->hasCoalescedExports() )
+ continue;
+ Diagnostics diag;
+ const dyld3::MachOAnalyzer* ma = (const dyld3::MachOAnalyzer*)image->machHeader();
+ ma->forEachWeakDef(diag, ^(const char *symbolName, uintptr_t imageOffset, bool isFromExportTrie) {
+ uintptr_t targetAddr = (uintptr_t)ma + imageOffset;
+ if ( isFromExportTrie ) {
+ // Avoid duplicating the string if we already have the symbol name
+ if ( context.weakDefMap.find(symbolName) != context.weakDefMap.end() )
+ return;
+ symbolName = strdup(symbolName);
+ }
+ context.weakDefMap.insert({ symbolName, { image, targetAddr } });
+ });
+ }
+ // for all images that need weak binding
+ for (int i=0; i < count; ++i) {
+ ImageLoader* imageBeingFixedUp = imagesNeedingCoalescing[i];
+ if ( imageBeingFixedUp->weakSymbolsBound(imageIndexes[i]) )
+ continue; // weak binding already completed
+ bool imageBeingFixedUpInCache = imageBeingFixedUp->inSharedCache();
+
+ if ( context.verboseWeakBind )
+ dyld::log("dyld: checking for weak symbols in %s\n", imageBeingFixedUp->getPath());
+ // for all symbols that need weak binding in this image
+ ImageLoader::CoalIterator coalIterator;
+ imageBeingFixedUp->initializeCoalIterator(coalIterator, i, imageIndexes[i]);
+ while ( !imageBeingFixedUp->incrementCoalIterator(coalIterator) ) {
+ const char* nameToCoalesce = coalIterator.symbolName;
+ uintptr_t targetAddr = 0;
+ const ImageLoader* targetImage;
+ // Seatch the map for a previous definition to use
+ auto weakDefIt = context.weakDefMap.find(nameToCoalesce);
+ if ( (weakDefIt != context.weakDefMap.end()) && (weakDefIt->second.first != nullptr) ) {
+ // Found a previous defition
+ targetImage = weakDefIt->second.first;
+ targetAddr = weakDefIt->second.second;
+ } else {
+ // scan all images looking for definition to use
+ for (int j=0; j < count; ++j) {
+ const ImageLoader* anImage = imagesNeedingCoalescing[j];
+ bool anImageInCache = anImage->inSharedCache();
+ // <rdar://problem/47986398> Don't look at images in dyld cache because cache is
+ // already coalesced. Only images outside cache can potentially override something in cache.
+ if ( anImageInCache && imageBeingFixedUpInCache )
+ continue;
+
+ //dyld::log("looking for %s in %s\n", nameToCoalesce, anImage->getPath());
+ const ImageLoader* foundIn;
+ const Symbol* sym = anImage->findExportedSymbol(nameToCoalesce, false, &foundIn);
+ if ( sym != NULL ) {
+ targetAddr = foundIn->getExportedSymbolAddress(sym, context);
+ targetImage = foundIn;
+ if ( context.verboseWeakBind )
+ dyld::log("dyld: found weak %s at 0x%lX in %s\n", nameToCoalesce, targetAddr, foundIn->getPath());
+ break;
+ }
+ }
+ }
+ if ( (targetAddr != 0) && (coalIterator.image != targetImage) ) {
+ coalIterator.image->updateUsesCoalIterator(coalIterator, targetAddr, (ImageLoader*)targetImage, 0, context);
+ if (weakDefIt == context.weakDefMap.end()) {
+ if (targetImage->neverUnload()) {
+ // Add never unload defs to the map for next time
+ context.weakDefMap.insert({ nameToCoalesce, { targetImage, targetAddr } });
+ if ( context.verboseWeakBind ) {
+ dyld::log("dyld: weak binding adding %s to map\n", nameToCoalesce);
+ }
+ } else {
+ // Add a placeholder for unloadable symbols which makes us fall back to the regular search
+ context.weakDefMap.insert({ nameToCoalesce, { targetImage, targetAddr } });
+ if ( context.verboseWeakBind ) {
+ dyld::log("dyld: weak binding adding unloadable placeholder %s to map\n", nameToCoalesce);
+ }
+ }
+ }
+ if ( context.verboseWeakBind )
+ dyld::log("dyld: adjusting uses of %s in %s to use definition from %s\n", nameToCoalesce, coalIterator.image->getPath(), targetImage->getPath());
+ }
+ }
+ imageBeingFixedUp->setWeakSymbolsBound(imageIndexes[i]);
+ }
+ }
+ else
+#endif // __MAC_OS_X_VERSION_MIN_REQUIRED
+ {
+ // make symbol iterators for each
+ ImageLoader::CoalIterator iterators[count];
+ ImageLoader::CoalIterator* sortedIts[count];
+ for(int i=0; i < count; ++i) {
+ imagesNeedingCoalescing[i]->initializeCoalIterator(iterators[i], i, imageIndexes[i]);
+ sortedIts[i] = &iterators[i];
+ if ( context.verboseWeakBind )
+ dyld::log("dyld: weak bind load order %d/%d for %s\n", i, count, imagesNeedingCoalescing[i]->getIndexedPath(imageIndexes[i]));
+ }
+
+ // walk all symbols keeping iterators in sync by
+ // only ever incrementing the iterator with the lowest symbol
+ int doneCount = 0;
+ while ( doneCount != count ) {
+ //for(int i=0; i < count; ++i)
+ // dyld::log("sym[%d]=%s ", sortedIts[i]->loadOrder, sortedIts[i]->symbolName);
+ //dyld::log("\n");
+ // increment iterator with lowest symbol
+ if ( sortedIts[0]->image->incrementCoalIterator(*sortedIts[0]) )
+ ++doneCount;
+ // re-sort iterators
+ for(int i=1; i < count; ++i) {
+ int result = strcmp(sortedIts[i-1]->symbolName, sortedIts[i]->symbolName);
+ if ( result == 0 )
+ sortedIts[i-1]->symbolMatches = true;
+ if ( result > 0 ) {
+ // new one is bigger then next, so swap
+ ImageLoader::CoalIterator* temp = sortedIts[i-1];
+ sortedIts[i-1] = sortedIts[i];
+ sortedIts[i] = temp;
+ }
+ if ( result < 0 )
+ break;
+ }
+ // process all matching symbols just before incrementing the lowest one that matches
+ if ( sortedIts[0]->symbolMatches && !sortedIts[0]->done ) {
+ const char* nameToCoalesce = sortedIts[0]->symbolName;
+ // pick first symbol in load order (and non-weak overrides weak)
+ uintptr_t targetAddr = 0;
+ ImageLoader* targetImage = NULL;
+ unsigned targetImageIndex = 0;
+ for(int i=0; i < count; ++i) {
+ if ( strcmp(iterators[i].symbolName, nameToCoalesce) == 0 ) {
+ if ( context.verboseWeakBind )
+ dyld::log("dyld: weak bind, found %s weak=%d in %s \n", nameToCoalesce, iterators[i].weakSymbol, iterators[i].image->getIndexedPath((unsigned)iterators[i].imageIndex));
+ if ( iterators[i].weakSymbol ) {
+ if ( targetAddr == 0 ) {
+ targetAddr = iterators[i].image->getAddressCoalIterator(iterators[i], context);
+ if ( targetAddr != 0 ) {
+ targetImage = iterators[i].image;
+ targetImageIndex = (unsigned)iterators[i].imageIndex;
+ }
+ }
+ }
+ else {
+ targetAddr = iterators[i].image->getAddressCoalIterator(iterators[i], context);
+ if ( targetAddr != 0 ) {
+ targetImage = iterators[i].image;
+ targetImageIndex = (unsigned)iterators[i].imageIndex;
+ // strong implementation found, stop searching
+ break;
+ }
+ }
+ }
+ }
+ // tell each to bind to this symbol (unless already bound)
+ if ( targetAddr != 0 ) {
+ if ( context.verboseWeakBind ) {
+ dyld::log("dyld: weak binding all uses of %s to copy from %s\n",
+ nameToCoalesce, targetImage->getIndexedShortName(targetImageIndex));
+ }
+ for(int i=0; i < count; ++i) {
+ if ( strcmp(iterators[i].symbolName, nameToCoalesce) == 0 ) {
+ if ( context.verboseWeakBind ) {
+ dyld::log("dyld: weak bind, setting all uses of %s in %s to 0x%lX from %s\n",
+ nameToCoalesce, iterators[i].image->getIndexedShortName((unsigned)iterators[i].imageIndex),
+ targetAddr, targetImage->getIndexedShortName(targetImageIndex));
+ }
+ if ( ! iterators[i].image->weakSymbolsBound(imageIndexes[i]) )
+ iterators[i].image->updateUsesCoalIterator(iterators[i], targetAddr, targetImage, targetImageIndex, context);
+ iterators[i].symbolMatches = false;
+ }
+ }
+ if (targetImage->neverUnload()) {
+ // Add never unload defs to the map for next time
+ context.weakDefMap.insert({ nameToCoalesce, { targetImage, targetAddr } });
+ if ( context.verboseWeakBind ) {
+ dyld::log("dyld: weak binding adding %s to map\n",
+ nameToCoalesce);
+ }
+ }
+ }
+
+ }
+ }
+
+ for (int i=0; i < count; ++i) {
+ if ( imagesNeedingCoalescing[i]->weakSymbolsBound(imageIndexes[i]) )
+ continue; // skip images already processed
+
+ if ( imagesNeedingCoalescing[i]->usesChainedFixups() ) {
+ // during binding of references to weak-def symbols, the dyld cache was patched
+ // but if main executable has non-weak override of operator new or delete it needs is handled here
+ for (const char* weakSymbolName : sTreatAsWeak) {
+ const ImageLoader* dummy;
+ imagesNeedingCoalescing[i]->resolveWeak(context, weakSymbolName, true, false, &dummy);
+ }
+ }
+#if __arm64e__
+ else {
+ // support traditional arm64 app on an arm64e device
+ // look for weak def symbols in this image which may override the cache
+ ImageLoader::CoalIterator coaler;
+ imagesNeedingCoalescing[i]->initializeCoalIterator(coaler, i, 0);
+ imagesNeedingCoalescing[i]->incrementCoalIterator(coaler);
+ while ( !coaler.done ) {
+ const ImageLoader* dummy;
+ // a side effect of resolveWeak() is to patch cache
+ imagesNeedingCoalescing[i]->resolveWeak(context, coaler.symbolName, true, false, &dummy);
+ imagesNeedingCoalescing[i]->incrementCoalIterator(coaler);
+ }
+ }
+#endif
+ }
+
+ // mark all as having all weak symbols bound
+ for(int i=0; i < count; ++i) {
+ imagesNeedingCoalescing[i]->setWeakSymbolsBound(imageIndexes[i]);
+ }
+ }
+ }
+
+ uint64_t t2 = mach_absolute_time();
+ fgTotalWeakBindTime += t2 - t1;
+
+ if ( context.verboseWeakBind )
+ dyld::log("dyld: weak bind end\n");
+}
+
+
+void ImageLoader::weakBindOld(const LinkContext& context)
+{
+ if ( context.verboseWeakBind )
+ dyld::log("dyld: weak bind start:\n");
+ uint64_t t1 = mach_absolute_time();
+ // get set of ImageLoaders that participate in coalecsing
+ ImageLoader* imagesNeedingCoalescing[fgImagesRequiringCoalescing];
+ unsigned imageIndexes[fgImagesRequiringCoalescing];
+ int count = context.getCoalescedImages(imagesNeedingCoalescing, imageIndexes);
+
+ // count how many have not already had weakbinding done
+ int countNotYetWeakBound = 0;
+ int countOfImagesWithWeakDefinitionsNotInSharedCache = 0;
+ for(int i=0; i < count; ++i) {
+ if ( ! imagesNeedingCoalescing[i]->weakSymbolsBound(imageIndexes[i]) )
+ ++countNotYetWeakBound;
+ if ( ! imagesNeedingCoalescing[i]->inSharedCache() )
+ ++countOfImagesWithWeakDefinitionsNotInSharedCache;
+ }
+
projects / apple / dyld.git / commitdiff
