]> git.saurik.com Git - apple/dyld.git/blobdiff - src/ImageLoader.cpp
dyld-635.2.tar.gz
[apple/dyld.git] / src / ImageLoader.cpp
index 23f89cbde1341333932f7daea3e7164f2576421b..28f89e27fee944bfc339312bfc3bec396aa5d950 100644 (file)
@@ -1,6 +1,6 @@
 /* -*- mode: C++; c-basic-offset: 4; tab-width: 4 -*-
  *
- * Copyright (c) 2004-2006 Apple Computer, Inc. All rights reserved.
+ * Copyright (c) 2004-2010 Apple Inc. All rights reserved.
  *
  * @APPLE_LICENSE_HEADER_START@
  * 
@@ -24,6 +24,7 @@
 
 #define __STDC_LIMIT_MACROS
 #include <stdint.h>
+#include <stdlib.h>
 #include <errno.h>
 #include <fcntl.h>
 #include <mach/mach.h>
 #include <sys/mman.h>
 #include <sys/param.h>
 #include <sys/mount.h>
+#include <sys/sysctl.h>
 #include <libkern/OSAtomic.h>
 
+#include "Tracing.h"
+
 #include "ImageLoader.h"
 
 
 uint32_t                                                               ImageLoader::fgImagesUsedFromSharedCache = 0;
 uint32_t                                                               ImageLoader::fgImagesWithUsedPrebinding = 0;
-uint32_t                                                               ImageLoader::fgImagesRequiringNoFixups = 0;
 uint32_t                                                               ImageLoader::fgImagesRequiringCoalescing = 0;
 uint32_t                                                               ImageLoader::fgImagesHasWeakDefinitions = 0;
 uint32_t                                                               ImageLoader::fgTotalRebaseFixups = 0;
@@ -53,54 +56,51 @@ uint32_t                                                            ImageLoader::fgTotalSegmentsMapped = 0;
 uint64_t                                                               ImageLoader::fgTotalBytesMapped = 0;
 uint64_t                                                               ImageLoader::fgTotalBytesPreFetched = 0;
 uint64_t                                                               ImageLoader::fgTotalLoadLibrariesTime;
+uint64_t                                                               ImageLoader::fgTotalObjCSetupTime = 0;
+uint64_t                                                               ImageLoader::fgTotalDebuggerPausedTime = 0;
+uint64_t                                                               ImageLoader::fgTotalRebindCacheTime = 0;
 uint64_t                                                               ImageLoader::fgTotalRebaseTime;
 uint64_t                                                               ImageLoader::fgTotalBindTime;
 uint64_t                                                               ImageLoader::fgTotalWeakBindTime;
 uint64_t                                                               ImageLoader::fgTotalDOF;
 uint64_t                                                               ImageLoader::fgTotalInitTime;
 uint16_t                                                               ImageLoader::fgLoadOrdinal = 0;
+uint32_t                                                               ImageLoader::fgSymbolTrieSearchs = 0;
+std::vector<ImageLoader::InterposeTuple>ImageLoader::fgInterposingTuples;
 uintptr_t                                                              ImageLoader::fgNextPIEDylibAddress = 0;
 
 
 
 ImageLoader::ImageLoader(const char* path, unsigned int libCount)
-       : fPath(path), fDevice(0), fInode(0), fLastModified(0), 
-       fPathHash(0), fDlopenReferenceCount(0), fStaticReferenceCount(0),
-       fDynamicReferenceCount(0), fDynamicReferences(NULL), fInitializerRecursiveLock(NULL), 
-       fDepth(0), fLoadOrder(0), fState(0), fLibraryCount(libCount), 
+       : fPath(path), fRealPath(NULL), fDevice(0), fInode(0), fLastModified(0), 
+       fPathHash(0), fDlopenReferenceCount(0), fInitializerRecursiveLock(NULL), 
+       fDepth(0), fLoadOrder(fgLoadOrdinal++), fState(0), fLibraryCount(libCount), 
        fAllLibraryChecksumsAndLoadAddressesMatch(false), fLeaveMapped(false), fNeverUnload(false),
        fHideSymbols(false), fMatchByInstallName(false),
-       fRegisteredDOF(false), fAllLazyPointersBound(false), fBeingRemoved(false), fAddFuncNotified(false),
-       fPathOwnedByImage(false), fWeakSymbolsBound(false)
+       fInterposed(false), fRegisteredDOF(false), fAllLazyPointersBound(false), 
+    fBeingRemoved(false), fAddFuncNotified(false),
+       fPathOwnedByImage(false), fIsReferencedDownward(false), 
+       fWeakSymbolsBound(false)
 {
        if ( fPath != NULL )
                fPathHash = hash(fPath);
+       if ( libCount > 512 )
+               dyld::throwf("too many dependent dylibs in %s", path);
 }
 
 
 void ImageLoader::deleteImage(ImageLoader* image)
 {
-       // this cannot be done in destructor because libImage() is implemented
-       // in a subclass
-       for(unsigned int i=0; i < image->libraryCount(); ++i) {
-               ImageLoader* lib = image->libImage(i);
-               if ( lib != NULL )
-                       lib->fStaticReferenceCount--;
-       }
        delete image;
 }
 
 
 ImageLoader::~ImageLoader()
 {
+       if ( fRealPath != NULL ) 
+               delete [] fRealPath;
        if ( fPathOwnedByImage && (fPath != NULL) ) 
                delete [] fPath;
-       if ( fDynamicReferences != NULL ) {
-               for (std::set<const ImageLoader*>::iterator it = fDynamicReferences->begin(); it != fDynamicReferences->end(); ++it ) {
-                       const_cast<ImageLoader*>(*it)->fDynamicReferenceCount--;
-               }
-               delete fDynamicReferences;
-       }
 }
 
 void ImageLoader::setFileInfo(dev_t device, ino_t inode, time_t modDate)
@@ -113,18 +113,7 @@ void ImageLoader::setFileInfo(dev_t device, ino_t inode, time_t modDate)
 void ImageLoader::setMapped(const LinkContext& context)
 {
        fState = dyld_image_state_mapped;
-       context.notifySingle(dyld_image_state_mapped, this);  // note: can throw exception
-}
-
-void ImageLoader::addDynamicReference(const ImageLoader* target)
-{
-       if ( fDynamicReferences == NULL )
-               fDynamicReferences = new std::set<const ImageLoader*>();
-       if ( fDynamicReferences->count(target) == 0 ) { 
-               fDynamicReferences->insert(target);
-               const_cast<ImageLoader*>(target)->fDynamicReferenceCount++;
-       }
-       //dyld::log("dyld: addDynamicReference() from %s to %s, fDynamicReferences->size()=%lu\n", this->getPath(), target->getPath(), fDynamicReferences->size());
+       context.notifySingle(dyld_image_state_mapped, this, NULL);  // note: can throw exception
 }
 
 int ImageLoader::compare(const ImageLoader* right) const
@@ -153,6 +142,7 @@ void ImageLoader::setPath(const char* path)
        strcpy((char*)fPath, path);
        fPathOwnedByImage = true;  // delete fPath when this image is destructed
        fPathHash = hash(fPath);
+       fRealPath = NULL;
 }
 
 void ImageLoader::setPathUnowned(const char* path)
@@ -165,6 +155,21 @@ void ImageLoader::setPathUnowned(const char* path)
        fPathHash = hash(fPath);
 }
 
+void ImageLoader::setPaths(const char* path, const char* realPath)
+{
+       this->setPath(path);
+       fRealPath = new char[strlen(realPath)+1];
+       strcpy((char*)fRealPath, realPath);
+}
+
+const char* ImageLoader::getRealPath() const 
+{ 
+       if ( fRealPath != NULL ) 
+               return fRealPath;
+       else
+               return fPath; 
+}
+
 
 uint32_t ImageLoader::hash(const char* path)
 {
@@ -192,15 +197,20 @@ bool ImageLoader::statMatch(const struct stat& stat_buf) const
        return ( (this->fDevice == stat_buf.st_dev) && (this->fInode == stat_buf.st_ino) );     
 }
 
-const char* ImageLoader::getShortName() const
+const char* ImageLoader::shortName(const char* fullName)
 {
        // try to return leaf name
-       if ( fPath != NULL ) {
-               const char* s = strrchr(fPath, '/');
+       if ( fullName != NULL ) {
+               const char* s = strrchr(fullName, '/');
                if ( s != NULL ) 
                        return &s[1];
        }
-       return fPath; 
+       return fullName;
+}
+
+const char* ImageLoader::getShortName() const
+{
+       return shortName(fPath);
 }
 
 void ImageLoader::setLeaveMapped()
@@ -230,8 +240,6 @@ time_t ImageLoader::lastModified() const
 
 bool ImageLoader::containsAddress(const void* addr) const
 {
-       if ( ! this->isLinked() )
-               return false;
        for(unsigned int i=0, e=segmentCount(); i < e; ++i) {
                const uint8_t* start = (const uint8_t*)segActualLoadAddress(i);
                const uint8_t* end = (const uint8_t*)segActualEndAddress(i);
@@ -246,6 +254,13 @@ bool ImageLoader::overlapsWithAddressRange(const void* start, const void* end) c
        for(unsigned int i=0, e=segmentCount(); i < e; ++i) {
                const uint8_t* segStart = (const uint8_t*)segActualLoadAddress(i);
                const uint8_t* segEnd = (const uint8_t*)segActualEndAddress(i);
+               if ( strcmp(segName(i), "__UNIXSTACK") == 0 ) {
+                       // __UNIXSTACK never slides.  This is the only place that cares
+                       // and checking for that segment name in segActualLoadAddress()
+                       // is too expensive.
+                       segStart -= getSlide();
+                       segEnd -= getSlide();
+               }
                if ( (start <= segStart) && (segStart < end) )
                        return true;
                if ( (start <= segEnd) && (segEnd < end) )
@@ -267,6 +282,16 @@ void ImageLoader::getMappedRegions(MappedRegion*& regions) const
 }
 
 
+
+bool ImageLoader::dependsOn(ImageLoader* image) {
+       for(unsigned int i=0; i < libraryCount(); ++i) {
+               if ( libImage(i) == image )
+                       return true;
+       }
+       return false;
+}
+
+
 static bool notInImgageList(const ImageLoader* image, const ImageLoader** dsiStart, const ImageLoader** dsiCur)
 {
        for (const ImageLoader** p = dsiStart; p < dsiCur; ++p)
@@ -275,16 +300,27 @@ static bool notInImgageList(const ImageLoader* image, const ImageLoader** dsiSta
        return true;
 }
 
+bool ImageLoader::findExportedSymbolAddress(const LinkContext& context, const char* symbolName,
+                                                                                       const ImageLoader* requestorImage, int requestorOrdinalOfDef,
+                                                                                       bool runResolver, const ImageLoader** foundIn, uintptr_t* address) const
+{
+       const Symbol* sym = this->findExportedSymbol(symbolName, true, foundIn);
+       if ( sym != NULL ) {
+               *address = (*foundIn)->getExportedSymbolAddress(sym, context, requestorImage, runResolver);
+               return true;
+       }
+       return false;
+}
+
 
 // private method that handles circular dependencies by only search any image once
 const ImageLoader::Symbol* ImageLoader::findExportedSymbolInDependentImagesExcept(const char* name, 
                        const ImageLoader** dsiStart, const ImageLoader**& dsiCur, const ImageLoader** dsiEnd, const ImageLoader** foundIn) const
 {
        const ImageLoader::Symbol* sym;
-       
        // search self
        if ( notInImgageList(this, dsiStart, dsiCur) ) {
-               sym = this->findExportedSymbol(name, false, foundIn);
+               sym = this->findExportedSymbol(name, false, this->getPath(), foundIn);
                if ( sym != NULL )
                        return sym;
                *dsiCur++ = this;
@@ -294,7 +330,7 @@ const ImageLoader::Symbol* ImageLoader::findExportedSymbolInDependentImagesExcep
        for(unsigned int i=0; i < libraryCount(); ++i) {
                ImageLoader* dependentImage = libImage(i);
                if ( (dependentImage != NULL) && notInImgageList(dependentImage, dsiStart, dsiCur) ) {
-                       const ImageLoader::Symbol* sym = dependentImage->findExportedSymbol(name, false, foundIn);
+                       sym = dependentImage->findExportedSymbol(name, false, libPath(i), foundIn);
                        if ( sym != NULL )
                                return sym;
                }
@@ -305,7 +341,7 @@ const ImageLoader::Symbol* ImageLoader::findExportedSymbolInDependentImagesExcep
                ImageLoader* dependentImage = libImage(i);
                if ( (dependentImage != NULL) && notInImgageList(dependentImage, dsiStart, dsiCur) ) {
                        *dsiCur++ = dependentImage; 
-                       const ImageLoader::Symbol* sym = dependentImage->findExportedSymbolInDependentImagesExcept(name, dsiStart, dsiCur, dsiEnd, foundIn);
+                       sym = dependentImage->findExportedSymbolInDependentImagesExcept(name, dsiStart, dsiCur, dsiEnd, foundIn);
                        if ( sym != NULL )
                                return sym;
                }
@@ -317,7 +353,7 @@ const ImageLoader::Symbol* ImageLoader::findExportedSymbolInDependentImagesExcep
 
 const ImageLoader::Symbol* ImageLoader::findExportedSymbolInDependentImages(const char* name, const LinkContext& context, const ImageLoader** foundIn) const
 {
-       unsigned int imageCount = context.imageCount();
+       unsigned int imageCount = context.imageCount()+2;
        const ImageLoader* dontSearchImages[imageCount];
        dontSearchImages[0] = this; // don't search this image
        const ImageLoader** cur = &dontSearchImages[1];
@@ -326,52 +362,188 @@ const ImageLoader::Symbol* ImageLoader::findExportedSymbolInDependentImages(cons
 
 const ImageLoader::Symbol* ImageLoader::findExportedSymbolInImageOrDependentImages(const char* name, const LinkContext& context, const ImageLoader** foundIn) const
 {
-       unsigned int imageCount = context.imageCount();
+       unsigned int imageCount = context.imageCount()+2;
        const ImageLoader* dontSearchImages[imageCount];
        const ImageLoader** cur = &dontSearchImages[0];
        return this->findExportedSymbolInDependentImagesExcept(name, &dontSearchImages[0], cur, &dontSearchImages[imageCount], foundIn);
 }
 
+// this is called by initializeMainExecutable() to interpose on the initial set of images
+void ImageLoader::applyInterposing(const LinkContext& context)
+{
+       dyld3::ScopedTimer timer(DBG_DYLD_TIMING_APPLY_INTERPOSING, 0, 0, 0);
+       if ( fgInterposingTuples.size() != 0 )
+               this->recursiveApplyInterposing(context);
+}
+
+
+uintptr_t ImageLoader::interposedAddress(const LinkContext& context, uintptr_t address, const ImageLoader* inImage, const ImageLoader* onlyInImage)
+{
+       //dyld::log("interposedAddress(0x%08llX), tupleCount=%lu\n", (uint64_t)address, fgInterposingTuples.size());
+       for (std::vector<InterposeTuple>::iterator it=fgInterposingTuples.begin(); it != fgInterposingTuples.end(); it++) {
+               //dyld::log("    interposedAddress: replacee=0x%08llX, replacement=0x%08llX, neverImage=%p, onlyImage=%p, inImage=%p\n", 
+               //                              (uint64_t)it->replacee, (uint64_t)it->replacement,  it->neverImage, it->onlyImage, inImage);
+               // replace all references to 'replacee' with 'replacement'
+               if ( (address == it->replacee) && (inImage != it->neverImage) && ((it->onlyImage == NULL) || (inImage == it->onlyImage)) ) {
+                       if ( context.verboseInterposing ) {
+                               dyld::log("dyld interposing: replace 0x%lX with 0x%lX\n", it->replacee, it->replacement);
+                       }
+                       return it->replacement;
+               }
+       }
+       return address;
+}
+
+void ImageLoader::applyInterposingToDyldCache(const LinkContext& context) {
+#if USES_CHAINED_BINDS
+       if (!context.dyldCache)
+               return;
+       if (fgInterposingTuples.empty())
+               return;
+       // For each of the interposed addresses, see if any of them are in the shared cache.  If so, find
+       // that image and apply its patch table to all uses.
+       uintptr_t cacheStart = (uintptr_t)context.dyldCache;
+       for (std::vector<InterposeTuple>::iterator it=fgInterposingTuples.begin(); it != fgInterposingTuples.end(); it++) {
+               if ( context.verboseInterposing )
+                       dyld::log("dyld: interpose: Trying to interpose address 0x%08llx\n", (uint64_t)it->replacee);
+               uint32_t imageIndex;
+               uint32_t cacheOffsetOfReplacee = (uint32_t)(it->replacee - cacheStart);
+               if (!context.dyldCache->addressInText(cacheOffsetOfReplacee, &imageIndex))
+                       continue;
+               dyld3::closure::ImageNum imageInCache = imageIndex+1;
+               if ( context.verboseInterposing )
+                       dyld::log("dyld: interpose: Found shared cache image %d for 0x%08llx\n", imageInCache, (uint64_t)it->replacee);
+               const dyld3::closure::Image* image = context.dyldCache->cachedDylibsImageArray()->imageForNum(imageInCache);
+               image->forEachPatchableExport(^(uint32_t cacheOffsetOfImpl, const char* exportName) {
+                       // Skip patching anything other than this symbol
+                       if (cacheOffsetOfImpl != cacheOffsetOfReplacee)
+                               return;
+                       if ( context.verboseInterposing )
+                               dyld::log("dyld: interpose: Patching uses of symbol %s in shared cache binary at %s\n", exportName, image->path());
+                       uintptr_t newLoc = it->replacement;
+                       image->forEachPatchableUseOfExport(cacheOffsetOfImpl, ^(dyld3::closure::Image::PatchableExport::PatchLocation patchLocation) {
+                               uintptr_t* loc = (uintptr_t*)(cacheStart+patchLocation.cacheOffset);
+#if __has_feature(ptrauth_calls)
+                               if ( patchLocation.authenticated ) {
+                                       dyld3::MachOLoaded::ChainedFixupPointerOnDisk fixupInfo;
+                                       fixupInfo.authRebase.auth      = true;
+                                       fixupInfo.authRebase.addrDiv   = patchLocation.usesAddressDiversity;
+                                       fixupInfo.authRebase.diversity = patchLocation.discriminator;
+                                       fixupInfo.authRebase.key       = patchLocation.key;
+                                       *loc = fixupInfo.signPointer(loc, newLoc + patchLocation.getAddend());
+                                       if ( context.verboseInterposing )
+                                               dyld::log("dyld: interpose: *%p = %p (JOP: diversity 0x%04X, addr-div=%d, key=%s)\n",
+                                                                 loc, (void*)*loc, patchLocation.discriminator, patchLocation.usesAddressDiversity, patchLocation.keyName());
+                                       return;
+                               }
+#endif
+                               if ( context.verboseInterposing )
+                                       dyld::log("dyld: interpose: *%p = 0x%0llX (dyld cache patch) to %s\n", loc, newLoc + patchLocation.getAddend(), exportName);
+                               *loc = newLoc + patchLocation.getAddend();
+                       });
+               });
+       }
+#endif
+}
+
+void ImageLoader::addDynamicInterposingTuples(const struct dyld_interpose_tuple array[], size_t count)
+{
+       for(size_t i=0; i < count; ++i) {
+               ImageLoader::InterposeTuple tuple;
+               tuple.replacement               = (uintptr_t)array[i].replacement;
+               tuple.neverImage                = NULL;
+               tuple.onlyImage             = this;
+               tuple.replacee                  = (uintptr_t)array[i].replacee;
+               // chain to any existing interpositions
+               for (std::vector<InterposeTuple>::iterator it=fgInterposingTuples.begin(); it != fgInterposingTuples.end(); it++) {
+                       if ( (it->replacee == tuple.replacee) && (it->onlyImage == this) ) {
+                               tuple.replacee = it->replacement;
+                       }
+               }
+               ImageLoader::fgInterposingTuples.push_back(tuple);
+       }
+}
 
-void ImageLoader::link(const LinkContext& context, bool forceLazysBound, bool preflightOnly, const RPathChain& loaderRPaths)
+// <rdar://problem/29099600> dyld should tell the kernel when it is doing root fix-ups
+void ImageLoader::vmAccountingSetSuspended(const LinkContext& context, bool suspend)
 {
-       //dyld::log("ImageLoader::link(%s) refCount=%d, neverUnload=%d\n", this->getPath(), fStaticReferenceCount, fNeverUnload);
+#if __arm__ || __arm64__
+       static bool sVmAccountingSuspended = false;
+       if ( suspend == sVmAccountingSuspended )
+               return;
+    if ( context.verboseBind )
+        dyld::log("set vm.footprint_suspend=%d\n", suspend);
+    int newValue = suspend ? 1 : 0;
+    int oldValue = 0;
+    size_t newlen = sizeof(newValue);
+    size_t oldlen = sizeof(oldValue);
+    int ret = sysctlbyname("vm.footprint_suspend", &oldValue, &oldlen, &newValue, newlen);
+    if ( context.verboseBind && (ret != 0) )
+               dyld::log("vm.footprint_suspend => %d, errno=%d\n", ret, errno);
+       sVmAccountingSuspended = suspend;
+#endif
+}
+
+
+void ImageLoader::link(const LinkContext& context, bool forceLazysBound, bool preflightOnly, bool neverUnload, const RPathChain& loaderRPaths, const char* imagePath)
+{
+       //dyld::log("ImageLoader::link(%s) refCount=%d, neverUnload=%d\n", imagePath, fDlopenReferenceCount, fNeverUnload);
        
+       // clear error strings
+       (*context.setErrorStrings)(0, NULL, NULL, NULL);
+
        uint64_t t0 = mach_absolute_time();
-       this->recursiveLoadLibraries(context, preflightOnly, loaderRPaths);
-       context.notifyBatch(dyld_image_state_dependents_mapped);
-       
+       this->recursiveLoadLibraries(context, preflightOnly, loaderRPaths, imagePath);
+       context.notifyBatch(dyld_image_state_dependents_mapped, preflightOnly);
+
        // we only do the loading step for preflights
        if ( preflightOnly )
                return;
-               
+
        uint64_t t1 = mach_absolute_time();
        context.clearAllDepths();
        this->recursiveUpdateDepth(context.imageCount());
 
-       uint64_t t2 = mach_absolute_time();
-       this->recursiveRebase(context);
-       context.notifyBatch(dyld_image_state_rebased);
-       
-       uint64_t t3 = mach_absolute_time();
-       this->recursiveBind(context, forceLazysBound);
+       __block uint64_t t2, t3, t4, t5;
+       {
+               dyld3::ScopedTimer(DBG_DYLD_TIMING_APPLY_FIXUPS, 0, 0, 0);
+               t2 = mach_absolute_time();
+               this->recursiveRebase(context);
+               context.notifyBatch(dyld_image_state_rebased, false);
+
+               t3 = mach_absolute_time();
+               if ( !context.linkingMainExecutable )
+                       this->recursiveBindWithAccounting(context, forceLazysBound, neverUnload);
+
+               t4 = mach_absolute_time();
+               if ( !context.linkingMainExecutable )
+                       this->weakBind(context);
+               t5 = mach_absolute_time();
+       }
 
-       uint64_t t4 = mach_absolute_time();
-       this->weakBind(context);
-       context.notifyBatch(dyld_image_state_bound);
+    if ( !context.linkingMainExecutable )
+        context.notifyBatch(dyld_image_state_bound, false);
+       uint64_t t6 = mach_absolute_time();     
 
-       uint64_t t5 = mach_absolute_time();     
        std::vector<DOFInfo> dofs;
        this->recursiveGetDOFSections(context, dofs);
        context.registerDOFs(dofs);
-       uint64_t t6 = mach_absolute_time();     
+       uint64_t t7 = mach_absolute_time();     
+
+       // interpose any dynamically loaded images
+       if ( !context.linkingMainExecutable && (fgInterposingTuples.size() != 0) ) {
+               dyld3::ScopedTimer timer(DBG_DYLD_TIMING_APPLY_INTERPOSING, 0, 0, 0);
+               this->recursiveApplyInterposing(context);
+       }
+
+       // clear error strings
+       (*context.setErrorStrings)(0, NULL, NULL, NULL);
 
-       
        fgTotalLoadLibrariesTime += t1 - t0;
        fgTotalRebaseTime += t3 - t2;
        fgTotalBindTime += t4 - t3;
        fgTotalWeakBindTime += t5 - t4;
-       fgTotalDOF += t6 - t5;
+       fgTotalDOF += t7 - t6;
        
        // done with initial dylib loads
        fgNextPIEDylibAddress = 0;
@@ -380,8 +552,7 @@ void ImageLoader::link(const LinkContext& context, bool forceLazysBound, bool pr
 
 void ImageLoader::printReferenceCounts()
 {
-       dyld::log("      dlopen=%d, static=%d, dynamic=%d for %s\n", 
-                               fDlopenReferenceCount, fStaticReferenceCount, fDynamicReferenceCount, getPath() );
+       dyld::log("      dlopen=%d for %s\n", fDlopenReferenceCount, getPath() );
 }
 
 
@@ -393,13 +564,39 @@ bool ImageLoader::decrementDlopenReferenceCount()
        return false;
 }
 
-void ImageLoader::runInitializers(const LinkContext& context)
+
+// <rdar://problem/14412057> upward dylib initializers can be run too soon
+// To handle dangling dylibs which are upward linked but not downward, all upward linked dylibs
+// have their initialization postponed until after the recursion through downward dylibs
+// has completed.
+void ImageLoader::processInitializers(const LinkContext& context, mach_port_t thisThread,
+                                                                        InitializerTimingList& timingInfo, ImageLoader::UninitedUpwards& images)
+{
+       uint32_t maxImageCount = context.imageCount()+2;
+       ImageLoader::UninitedUpwards upsBuffer[maxImageCount];
+       ImageLoader::UninitedUpwards& ups = upsBuffer[0];
+       ups.count = 0;
+       // Calling recursive init on all images in images list, building a new list of
+       // uninitialized upward dependencies.
+       for (uintptr_t i=0; i < images.count; ++i) {
+               images.images[i]->recursiveInitialization(context, thisThread, images.images[i]->getPath(), timingInfo, ups);
+       }
+       // If any upward dependencies remain, init them.
+       if ( ups.count > 0 )
+               processInitializers(context, thisThread, timingInfo, ups);
+}
+
+
+void ImageLoader::runInitializers(const LinkContext& context, InitializerTimingList& timingInfo)
 {
        uint64_t t1 = mach_absolute_time();
-       mach_port_t this_thread = mach_thread_self();
-       this->recursiveInitialization(context, this_thread);
-       context.notifyBatch(dyld_image_state_initialized);
-       mach_port_deallocate(mach_task_self(), this_thread);
+       mach_port_t thisThread = mach_thread_self();
+       ImageLoader::UninitedUpwards up;
+       up.count = 1;
+       up.images[0] = this;
+       processInitializers(context, thisThread, timingInfo, up);
+       context.notifyBatch(dyld_image_state_initialized, false);
+       mach_port_deallocate(mach_task_self(), thisThread);
        uint64_t t2 = mach_absolute_time();
        fgTotalInitTime += (t2 - t1);
 }
@@ -430,6 +627,29 @@ bool ImageLoader::allDependentLibrariesAsWhenPreBound() const
 }
 
 
+void ImageLoader::markedUsedRecursive(const std::vector<DynamicReference>& dynamicReferences)
+{
+       // already visited here
+       if ( fMarkedInUse )
+               return;
+       fMarkedInUse = true;
+       
+       // clear mark on all statically dependent dylibs
+       for(unsigned int i=0; i < libraryCount(); ++i) {
+               ImageLoader* dependentImage = libImage(i);
+               if ( dependentImage != NULL ) {
+                       dependentImage->markedUsedRecursive(dynamicReferences);
+               }
+       }
+       
+       // clear mark on all dynamically dependent dylibs
+       for (std::vector<ImageLoader::DynamicReference>::const_iterator it=dynamicReferences.begin(); it != dynamicReferences.end(); ++it) {
+               if ( it->from == this )
+                       it->to->markedUsedRecursive(dynamicReferences);
+       }
+       
+}
+
 unsigned int ImageLoader::recursiveUpdateDepth(unsigned int maxDepth)
 {
        // the purpose of this phase is to make the images sortable such that 
@@ -443,7 +663,7 @@ unsigned int ImageLoader::recursiveUpdateDepth(unsigned int maxDepth)
                unsigned int minDependentDepth = maxDepth;
                for(unsigned int i=0; i < libraryCount(); ++i) {
                        ImageLoader* dependentImage = libImage(i);
-                       if ( dependentImage != NULL ) {
+                       if ( (dependentImage != NULL) && !libIsUpward(i) ) {
                                unsigned int d = dependentImage->recursiveUpdateDepth(maxDepth);
                                if ( d < minDependentDepth )
                                        minDependentDepth = d;
@@ -458,14 +678,13 @@ unsigned int ImageLoader::recursiveUpdateDepth(unsigned int maxDepth)
 }
 
 
-void ImageLoader::recursiveLoadLibraries(const LinkContext& context, bool preflightOnly, const RPathChain& loaderRPaths)
+void ImageLoader::recursiveLoadLibraries(const LinkContext& context, bool preflightOnly, const RPathChain& loaderRPaths, const char* loadPath)
 {
        if ( fState < dyld_image_state_dependents_mapped ) {
                // break cycles
                fState = dyld_image_state_dependents_mapped;
                
                // get list of libraries this image needs
-               //dyld::log("ImageLoader::recursiveLoadLibraries() %ld = %d*%ld\n", fLibrariesCount*sizeof(DependentLibrary), fLibrariesCount, sizeof(DependentLibrary));
                DependentLibraryInfo libraryInfos[fLibraryCount]; 
                this->doGetDependentLibraries(libraryInfos);
                
@@ -479,30 +698,39 @@ void ImageLoader::recursiveLoadLibraries(const LinkContext& context, bool prefli
                for(unsigned int i=0; i < fLibraryCount; ++i){
                        ImageLoader* dependentLib;
                        bool depLibReExported = false;
-                       bool depLibReRequired = false;
+                       bool depLibRequired = false;
                        bool depLibCheckSumsMatch = false;
                        DependentLibraryInfo& requiredLibInfo = libraryInfos[i];
-#if DYLD_SHARED_CACHE_SUPPORT
                        if ( preflightOnly && context.inSharedCache(requiredLibInfo.name) ) {
                                // <rdar://problem/5910137> dlopen_preflight() on image in shared cache leaves it loaded but not objc initialized
                                // in preflight mode, don't even load dylib that are in the shared cache because they will never be unloaded
-                               setLibImage(i, NULL, false);
+                               setLibImage(i, NULL, false, false);
                                continue;
                        }
-#endif
                        try {
-                               dependentLib = context.loadLibrary(requiredLibInfo.name, true, this->getPath(), &thisRPaths);
+                               unsigned cacheIndex;
+                               bool enforceIOSMac = false;
+               #if __MAC_OS_X_VERSION_MIN_REQUIRED
+                               const dyld3::MachOFile* mf = (dyld3::MachOFile*)this->machHeader();
+                               if ( mf->supportsPlatform(dyld3::Platform::iOSMac) && !mf->supportsPlatform(dyld3::Platform::macOS) )
+                                       enforceIOSMac = true;
+               #endif
+                               dependentLib = context.loadLibrary(requiredLibInfo.name, true, this->getPath(), &thisRPaths, enforceIOSMac, cacheIndex);
                                if ( dependentLib == this ) {
                                        // found circular reference, perhaps DYLD_LIBARY_PATH is causing this rdar://problem/3684168 
-                                       dependentLib = context.loadLibrary(requiredLibInfo.name, false, NULL, NULL);
+                                       dependentLib = context.loadLibrary(requiredLibInfo.name, false, NULL, NULL, enforceIOSMac, cacheIndex);
                                        if ( dependentLib != this )
                                                dyld::warn("DYLD_ setting caused circular dependency in %s\n", this->getPath());
                                }
                                if ( fNeverUnload )
                                        dependentLib->setNeverUnload();
-                               dependentLib->fStaticReferenceCount += 1;
-                               LibraryInfo actualInfo = dependentLib->doGetLibraryInfo();
-                               depLibReRequired = requiredLibInfo.required;
+                               if ( requiredLibInfo.upward ) {
+                               }
+                               else { 
+                                       dependentLib->fIsReferencedDownward = true;
+                               }
+                               LibraryInfo actualInfo = dependentLib->doGetLibraryInfo(requiredLibInfo.info);
+                               depLibRequired = requiredLibInfo.required;
                                depLibCheckSumsMatch = ( actualInfo.checksum == requiredLibInfo.info.checksum );
                                depLibReExported = requiredLibInfo.reExported;
                                if ( ! depLibReExported ) {
@@ -510,14 +738,21 @@ void ImageLoader::recursiveLoadLibraries(const LinkContext& context, bool prefli
                                        depLibReExported = dependentLib->isSubframeworkOf(context, this) || this->hasSubLibrary(context, dependentLib);
                                }
                                // check found library version is compatible
-                               if ( actualInfo.minVersion < requiredLibInfo.info.minVersion ) {
+                               // <rdar://problem/89200806> 0xFFFFFFFF is wildcard that matches any version
+                               if ( (requiredLibInfo.info.minVersion != 0xFFFFFFFF) && (actualInfo.minVersion < requiredLibInfo.info.minVersion)
+                                               && ((dyld3::MachOFile*)(dependentLib->machHeader()))->enforceCompatVersion() ) {
+                                       // record values for possible use by CrashReporter or Finder
                                        dyld::throwf("Incompatible library version: %s requires version %d.%d.%d or later, but %s provides version %d.%d.%d",
                                                        this->getShortName(), requiredLibInfo.info.minVersion >> 16, (requiredLibInfo.info.minVersion >> 8) & 0xff, requiredLibInfo.info.minVersion & 0xff,
                                                        dependentLib->getShortName(), actualInfo.minVersion >> 16, (actualInfo.minVersion >> 8) & 0xff, actualInfo.minVersion & 0xff);
                                }
-                               // prebinding for this image disabled if any dependent library changed or slid
-                               if ( !depLibCheckSumsMatch || (dependentLib->getSlide() != 0) )
+                               // prebinding for this image disabled if any dependent library changed
+                               //if ( !depLibCheckSumsMatch )
+                               //      canUsePrelinkingInfo = false;
+                               // prebinding for this image disabled unless both this and dependent are in the shared cache
+                               if ( !dependentLib->inSharedCache() || !this->inSharedCache() )
                                        canUsePrelinkingInfo = false;
+                                       
                                //if ( context.verbosePrebinding ) {
                                //      if ( !requiredLib.checksumMatches )
                                //              fprintf(stderr, "dyld: checksum mismatch, (%u v %u) for %s referencing %s\n", 
@@ -531,13 +766,29 @@ void ImageLoader::recursiveLoadLibraries(const LinkContext& context, bool prefli
                                //      fprintf(stderr, "dyld: exception during processing for %s referencing %s\n", this->getPath(), dependentLib->getPath());         
                                if ( requiredLibInfo.required ) {
                                        fState = dyld_image_state_mapped;
-                                       dyld::throwf("Library not loaded: %s\n  Referenced from: %s\n  Reason: %s", requiredLibInfo.name, this->getPath(), msg);
+                                       // record values for possible use by CrashReporter or Finder
+                                       if ( strstr(msg, "Incompatible library version") != NULL )
+                                               (*context.setErrorStrings)(DYLD_EXIT_REASON_DYLIB_WRONG_VERSION, this->getPath(), requiredLibInfo.name, NULL);
+                                       else if ( strstr(msg, "architecture") != NULL )
+                                               (*context.setErrorStrings)(DYLD_EXIT_REASON_DYLIB_WRONG_ARCH, this->getPath(), requiredLibInfo.name, NULL);
+                                       else if ( strstr(msg, "file system sandbox") != NULL )
+                                               (*context.setErrorStrings)(DYLD_EXIT_REASON_FILE_SYSTEM_SANDBOX, this->getPath(), requiredLibInfo.name, NULL);
+                                       else if ( strstr(msg, "code signature") != NULL )
+                                               (*context.setErrorStrings)(DYLD_EXIT_REASON_CODE_SIGNATURE, this->getPath(), requiredLibInfo.name, NULL);
+                                       else if ( strstr(msg, "malformed") != NULL )
+                                               (*context.setErrorStrings)(DYLD_EXIT_REASON_MALFORMED_MACHO, this->getPath(), requiredLibInfo.name, NULL);
+                                       else
+                                               (*context.setErrorStrings)(DYLD_EXIT_REASON_DYLIB_MISSING, this->getPath(), requiredLibInfo.name, NULL);
+                                       const char* newMsg = dyld::mkstringf("Library not loaded: %s\n  Referenced from: %s\n  Reason: %s", requiredLibInfo.name, this->getRealPath(), msg);
+                                       free((void*)msg);       // our free() will do nothing if msg is a string literal
+                                       throw newMsg;
                                }
+                               free((void*)msg);       // our free() will do nothing if msg is a string literal
                                // ok if weak library not found
                                dependentLib = NULL;
                                canUsePrelinkingInfo = false;  // this disables all prebinding, we may want to just slam import vectors for this lib to zero
                        }
-                       setLibImage(i, dependentLib, depLibReExported);
+                       setLibImage(i, dependentLib, depLibReExported, requiredLibInfo.upward);
                }
                fAllLibraryChecksumsAndLoadAddressesMatch = canUsePrelinkingInfo;
 
@@ -545,7 +796,7 @@ void ImageLoader::recursiveLoadLibraries(const LinkContext& context, bool prefli
                for(unsigned int i=0; i < libraryCount(); ++i) {
                        ImageLoader* dependentImage = libImage(i);
                        if ( dependentImage != NULL ) { 
-                               dependentImage->recursiveLoadLibraries(context, preflightOnly, thisRPaths);
+                               dependentImage->recursiveLoadLibraries(context, preflightOnly, thisRPaths, libraryInfos[i].name);
                        }
                }
                
@@ -587,20 +838,49 @@ void ImageLoader::recursiveRebase(const LinkContext& context)
                        doRebase(context);
                        
                        // notify
-                       context.notifySingle(dyld_image_state_rebased, this);
+                       context.notifySingle(dyld_image_state_rebased, this, NULL);
                }
                catch (const char* msg) {
                        // this image is not rebased
                        fState = dyld_image_state_dependents_mapped;
+            CRSetCrashLogMessage2(NULL);
                        throw;
                }
        }
 }
 
+void ImageLoader::recursiveApplyInterposing(const LinkContext& context)
+{ 
+       if ( ! fInterposed ) {
+               // break cycles
+               fInterposed = true;
+               
+               try {
+                       // interpose lower level libraries first
+                       for(unsigned int i=0; i < libraryCount(); ++i) {
+                               ImageLoader* dependentImage = libImage(i);
+                               if ( dependentImage != NULL )
+                                       dependentImage->recursiveApplyInterposing(context);
+                       }
+                               
+                       // interpose this image
+                       doInterpose(context);
+               }
+               catch (const char* msg) {
+                       // this image is not interposed
+                       fInterposed = false;
+                       throw;
+               }
+       }
+}
 
+void ImageLoader::recursiveBindWithAccounting(const LinkContext& context, bool forceLazysBound, bool neverUnload)
+{
+       this->recursiveBind(context, forceLazysBound, neverUnload);
+       vmAccountingSetSuspended(context, false);
+}
 
-
-void ImageLoader::recursiveBind(const LinkContext& context, bool forceLazysBound)
+void ImageLoader::recursiveBind(const LinkContext& context, bool forceLazysBound, bool neverUnload)
 {
        // Normally just non-lazy pointers are bound immediately.
        // The exceptions are:
@@ -615,52 +895,75 @@ void ImageLoader::recursiveBind(const LinkContext& context, bool forceLazysBound
                        for(unsigned int i=0; i < libraryCount(); ++i) {
                                ImageLoader* dependentImage = libImage(i);
                                if ( dependentImage != NULL )
-                                       dependentImage->recursiveBind(context, forceLazysBound);
+                                       dependentImage->recursiveBind(context, forceLazysBound, neverUnload);
                        }
                        // bind this image
                        this->doBind(context, forceLazysBound); 
                        // mark if lazys are also bound
                        if ( forceLazysBound || this->usablePrebinding(context) )
                                fAllLazyPointersBound = true;
+                       // mark as never-unload if requested
+                       if ( neverUnload )
+                               this->setNeverUnload();
                                
-                       context.notifySingle(dyld_image_state_bound, this);
+                       context.notifySingle(dyld_image_state_bound, this, NULL);
                }
                catch (const char* msg) {
                        // restore state
                        fState = dyld_image_state_rebased;
+            CRSetCrashLogMessage2(NULL);
                        throw;
                }
        }
 }
 
+
+// These are mangled symbols for all the variants of operator new and delete
+// which a main executable can define (non-weak) and override the
+// weak-def implementation in the OS.
+static const char* sTreatAsWeak[] = {
+    "__Znwm", "__ZnwmRKSt9nothrow_t",
+    "__Znam", "__ZnamRKSt9nothrow_t",
+    "__ZdlPv", "__ZdlPvRKSt9nothrow_t", "__ZdlPvm",
+    "__ZdaPv", "__ZdaPvRKSt9nothrow_t", "__ZdaPvm",
+    "__ZnwmSt11align_val_t", "__ZnwmSt11align_val_tRKSt9nothrow_t",
+    "__ZnamSt11align_val_t", "__ZnamSt11align_val_tRKSt9nothrow_t",
+    "__ZdlPvSt11align_val_t", "__ZdlPvSt11align_val_tRKSt9nothrow_t", "__ZdlPvmSt11align_val_t",
+    "__ZdaPvSt11align_val_t", "__ZdaPvSt11align_val_tRKSt9nothrow_t", "__ZdaPvmSt11align_val_t"
+};
+
+
+
 void ImageLoader::weakBind(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];
-       int count = context.getCoalescedImages(imagesNeedingCoalescing);
+       unsigned imageIndexes[fgImagesRequiringCoalescing];
+       int count = context.getCoalescedImages(imagesNeedingCoalescing, imageIndexes);
        
        // count how many have not already had weakbinding done
        int countNotYetWeakBound = 0;
-       int countOfImagesWithWeakDefinitions = 0;
+       int countOfImagesWithWeakDefinitionsNotInSharedCache = 0;
        for(int i=0; i < count; ++i) {
-               if ( ! imagesNeedingCoalescing[i]->fWeakSymbolsBound )
+               if ( ! imagesNeedingCoalescing[i]->weakSymbolsBound(imageIndexes[i]) )
                        ++countNotYetWeakBound;
-               if ( imagesNeedingCoalescing[i]->hasCoalescedExports() )
-                       ++countOfImagesWithWeakDefinitions;
+               if ( ! imagesNeedingCoalescing[i]->inSharedCache() )
+                       ++countOfImagesWithWeakDefinitionsNotInSharedCache;
        }
 
        // don't need to do any coalescing if only one image has overrides, or all have already been done
-       if ( (countOfImagesWithWeakDefinitions > 1) && (countNotYetWeakBound > 0) ) {
+       if ( (countOfImagesWithWeakDefinitionsNotInSharedCache > 0) && (countNotYetWeakBound > 0) ) {
                // 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);
+                       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]->getPath());
+                               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 
@@ -693,51 +996,90 @@ void ImageLoader::weakBind(const LinkContext& context)
                                // 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->getPath());
+                                                       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 )
+                                                               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;
                                                        }
                                                }
                                        }
                                }
-                               if ( context.verboseWeakBind )
-                                       dyld::log("dyld: weak binding all uses of %s to copy from %s\n", nameToCoalesce, targetImage->getShortName());
-                               
                                // 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->getShortName(), targetAddr, targetImage->getShortName());
-                                                       if ( ! iterators[i].image->fWeakSymbolsBound )
-                                                               iterators[i].image->updateUsesCoalIterator(iterators[i], targetAddr, targetImage, context);
+                                                       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 __arm64e__
+               for (int i=0; i < count; ++i) {
+                       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
+                               if ( !imagesNeedingCoalescing[i]->weakSymbolsBound(imageIndexes[i]) ) {
+                                       for (const char* weakSymbolName : sTreatAsWeak) {
+                                               const ImageLoader* dummy;
+                                               imagesNeedingCoalescing[i]->resolveWeak(context, weakSymbolName, true, false, &dummy);
+                                       }
+                               }
+                       }
+                       else {
+                               // 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 ) {
+                                       imagesNeedingCoalescing[i]->incrementCoalIterator(coaler);
+                                       const ImageLoader* dummy;
+                                       // a side effect of resolveWeak() is to patch cache
+                                       imagesNeedingCoalescing[i]->resolveWeak(context, coaler.symbolName, true, false, &dummy);
+                               }
+                       }
+               }
+#endif
+
                // mark all as having all weak symbols bound
                for(int i=0; i < count; ++i) {
-                       imagesNeedingCoalescing[i]->fWeakSymbolsBound = true;
+                       imagesNeedingCoalescing[i]->setWeakSymbolsBound(imageIndexes[i]);
                }
        }
+
+       uint64_t t2 = mach_absolute_time();
+       fgTotalWeakBindTime += t2  - t1;
+       
        if ( context.verboseWeakBind )
                dyld::log("dyld: weak bind end\n");
 }
@@ -760,6 +1102,19 @@ void ImageLoader::recursiveGetDOFSections(const LinkContext& context, std::vecto
        }
 }
 
+void ImageLoader::setNeverUnloadRecursive() {
+       if ( ! fNeverUnload ) {
+               // break cycles
+               fNeverUnload = true;
+               
+               // gather lower level libraries first
+               for(unsigned int i=0; i < libraryCount(); ++i) {
+                       ImageLoader* dependentImage = libImage(i);
+                       if ( dependentImage != NULL )
+                               dependentImage->setNeverUnloadRecursive();
+               }
+       }
+}
 
 void ImageLoader::recursiveSpinLock(recursive_lock& rlock)
 {
@@ -780,8 +1135,21 @@ void ImageLoader::recursiveSpinUnLock()
                fInitializerRecursiveLock = NULL;
 }
 
+void ImageLoader::InitializerTimingList::addTime(const char* name, uint64_t time)
+{
+       for (int i=0; i < count; ++i) {
+               if ( strcmp(images[i].shortName, name) == 0 ) {
+                       images[i].initTime += time;
+                       return;
+               }
+       }
+       images[count].initTime = time;
+       images[count].shortName = name;
+       ++count;
+}
 
-void ImageLoader::recursiveInitialization(const LinkContext& context, mach_port_t this_thread)
+void ImageLoader::recursiveInitialization(const LinkContext& context, mach_port_t this_thread, const char* pathToInitialize,
+                                                                                 InitializerTimingList& timingInfo, UninitedUpwards& uninitUps)
 {
        recursive_lock lock_info(this_thread);
        recursiveSpinLock(lock_info);
@@ -794,28 +1162,40 @@ void ImageLoader::recursiveInitialization(const LinkContext& context, mach_port_
                        // initialize lower level libraries first
                        for(unsigned int i=0; i < libraryCount(); ++i) {
                                ImageLoader* dependentImage = libImage(i);
-                               if ( dependentImage != NULL )
-                               // don't try to initialize stuff "above" me
-                               if ( (dependentImage != NULL) && (dependentImage->fDepth >= fDepth) )
-                                       dependentImage->recursiveInitialization(context, this_thread);
+                               if ( dependentImage != NULL ) {
+                                       // don't try to initialize stuff "above" me yet
+                                       if ( libIsUpward(i) ) {
+                                               uninitUps.images[uninitUps.count] = dependentImage;
+                                               uninitUps.count++;
+                                       }
+                                       else if ( dependentImage->fDepth >= fDepth ) {
+                                               dependentImage->recursiveInitialization(context, this_thread, libPath(i), timingInfo, uninitUps);
+                                       }
+                }
                        }
                        
                        // record termination order
                        if ( this->needsTermination() )
                                context.terminationRecorder(this);
                        
-                       // let objc know we are about to initalize this image
+                       // let objc know we are about to initialize this image
+                       uint64_t t1 = mach_absolute_time();
                        fState = dyld_image_state_dependents_initialized;
                        oldState = fState;
-                       context.notifySingle(dyld_image_state_dependents_initialized, this);
-
+                       context.notifySingle(dyld_image_state_dependents_initialized, this, &timingInfo);
+                       
                        // initialize this image
-                       this->doInitialization(context);
+                       bool hasInitializers = this->doInitialization(context);
 
-                       // let anyone know we finished initalizing this image
+                       // let anyone know we finished initializing this image
                        fState = dyld_image_state_initialized;
                        oldState = fState;
-                       context.notifySingle(dyld_image_state_initialized, this);
+                       context.notifySingle(dyld_image_state_initialized, this, NULL);
+                       
+                       if ( hasInitializers ) {
+                               uint64_t t2 = mach_absolute_time();
+                               timingInfo.addTime(this->getShortName(), t2-t1);
+                       }
                }
                catch (const char* msg) {
                        // this image is not initialized
@@ -834,21 +1214,26 @@ static void printTime(const char* msg, uint64_t partTime, uint64_t totalTime)
        static uint64_t sUnitsPerSecond = 0;
        if ( sUnitsPerSecond == 0 ) {
                struct mach_timebase_info timeBaseInfo;
-               if ( mach_timebase_info(&timeBaseInfo) == KERN_SUCCESS ) {
-                       sUnitsPerSecond = 1000000000ULL * timeBaseInfo.denom / timeBaseInfo.numer;
-               }
+               if ( mach_timebase_info(&timeBaseInfo) != KERN_SUCCESS )
+                       return;
+               sUnitsPerSecond = 1000000000ULL * timeBaseInfo.denom / timeBaseInfo.numer;
        }
        if ( partTime < sUnitsPerSecond ) {
-               uint32_t milliSecondsTimesHundred = (partTime*100000)/sUnitsPerSecond;
-               uint32_t milliSeconds = milliSecondsTimesHundred/100;
-               uint32_t percentTimesTen = (partTime*1000)/totalTime;
+               uint32_t milliSecondsTimesHundred = (uint32_t)((partTime*100000)/sUnitsPerSecond);
+               uint32_t milliSeconds = (uint32_t)(milliSecondsTimesHundred/100);
+               uint32_t percentTimesTen = (uint32_t)((partTime*1000)/totalTime);
                uint32_t percent = percentTimesTen/10;
-               dyld::log("%s: %u.%02u milliseconds (%u.%u%%)\n", msg, milliSeconds, milliSecondsTimesHundred-milliSeconds*100, percent, percentTimesTen-percent*10);
+               if ( milliSeconds >= 100 )
+                       dyld::log("%s: %u.%02u milliseconds (%u.%u%%)\n", msg, milliSeconds, milliSecondsTimesHundred-milliSeconds*100, percent, percentTimesTen-percent*10);
+               else if ( milliSeconds >= 10 )
+                       dyld::log("%s:  %u.%02u milliseconds (%u.%u%%)\n", msg, milliSeconds, milliSecondsTimesHundred-milliSeconds*100, percent, percentTimesTen-percent*10);
+               else
+                       dyld::log("%s:   %u.%02u milliseconds (%u.%u%%)\n", msg, milliSeconds, milliSecondsTimesHundred-milliSeconds*100, percent, percentTimesTen-percent*10);
        }
        else {
-               uint32_t secondsTimeTen = (partTime*10)/sUnitsPerSecond;
+               uint32_t secondsTimeTen = (uint32_t)((partTime*10)/sUnitsPerSecond);
                uint32_t seconds = secondsTimeTen/10;
-               uint32_t percentTimesTen = (partTime*1000)/totalTime;
+               uint32_t percentTimesTen = (uint32_t)((partTime*1000)/totalTime);
                uint32_t percent = percentTimesTen/10;
                dyld::log("%s: %u.%u seconds (%u.%u%%)\n", msg, seconds, secondsTimeTen-seconds*10, percent, percentTimesTen-percent*10);
        }
@@ -876,20 +1261,45 @@ static char* commatize(uint64_t in, char* out)
 }
 
 
-void ImageLoader::printStatistics(unsigned int imageCount)
+void ImageLoader::printStatistics(unsigned int imageCount, const InitializerTimingList& timingInfo)
 {
-       uint64_t totalTime = fgTotalLoadLibrariesTime + fgTotalRebaseTime + fgTotalBindTime + fgTotalWeakBindTime + fgTotalDOF + fgTotalInitTime;
+       uint64_t totalTime = fgTotalLoadLibrariesTime  + fgTotalRebaseTime + fgTotalBindTime + fgTotalWeakBindTime + fgTotalDOF + fgTotalInitTime;
+
+       uint64_t totalDyldTime = totalTime - fgTotalDebuggerPausedTime - fgTotalRebindCacheTime;
+       printTime("Total pre-main time", totalDyldTime, totalDyldTime);
+       printTime("         dylib loading time", fgTotalLoadLibrariesTime-fgTotalDebuggerPausedTime, totalDyldTime);
+       printTime("        rebase/binding time", fgTotalRebaseTime+fgTotalBindTime+fgTotalWeakBindTime-fgTotalRebindCacheTime, totalDyldTime);
+       printTime("            ObjC setup time", fgTotalObjCSetupTime, totalDyldTime);
+       printTime("           initializer time", fgTotalInitTime-fgTotalObjCSetupTime, totalDyldTime);
+       dyld::log("           slowest intializers :\n");
+       for (uintptr_t i=0; i < timingInfo.count; ++i) {
+               uint64_t t = timingInfo.images[i].initTime;
+               if ( t*50 < totalDyldTime )
+                       continue;
+               dyld::log("%30s ", timingInfo.images[i].shortName);
+               if ( strncmp(timingInfo.images[i].shortName, "libSystem.", 10) == 0 )
+                       t -= fgTotalObjCSetupTime;
+                       printTime("", t, totalDyldTime);
+       }
+       dyld::log("\n");
+}
+
+void ImageLoader::printStatisticsDetails(unsigned int imageCount, const InitializerTimingList& timingInfo)
+{
+       uint64_t totalTime = fgTotalLoadLibrariesTime  + fgTotalRebaseTime + fgTotalBindTime + fgTotalWeakBindTime + fgTotalDOF + fgTotalInitTime;
        char commaNum1[40];
        char commaNum2[40];
 
-       printTime("total time", totalTime, totalTime);
-       dyld::log("total images loaded:  %d (%u from dyld shared cache, %u needed no fixups)\n", imageCount, fgImagesUsedFromSharedCache, fgImagesRequiringNoFixups);
-       dyld::log("total segments mapped: %u, into %llu pages with %llu pages pre-fetched\n", fgTotalSegmentsMapped, fgTotalBytesMapped/4096, fgTotalBytesPreFetched/4096);
-       printTime("total images loading time", fgTotalLoadLibrariesTime, totalTime);
-       printTime("total dtrace DOF registration time", fgTotalDOF, totalTime);
-       dyld::log("total rebase fixups:  %s\n", commatize(fgTotalRebaseFixups, commaNum1));
-       printTime("total rebase fixups time", fgTotalRebaseTime, totalTime);
-       dyld::log("total binding fixups: %s\n", commatize(fgTotalBindFixups, commaNum1));
+       printTime("  total time", totalTime, totalTime);
+       dyld::log("  total images loaded:  %d (%u from dyld shared cache)\n", imageCount, fgImagesUsedFromSharedCache);
+       dyld::log("  total segments mapped: %u, into %llu pages with %llu pages pre-fetched\n", fgTotalSegmentsMapped, fgTotalBytesMapped/4096, fgTotalBytesPreFetched/4096);
+       printTime("  total images loading time", fgTotalLoadLibrariesTime, totalTime);
+       printTime("  total load time in ObjC", fgTotalObjCSetupTime, totalTime);
+       printTime("  total debugger pause time", fgTotalDebuggerPausedTime, totalTime);
+       printTime("  total dtrace DOF registration time", fgTotalDOF, totalTime);
+       dyld::log("  total rebase fixups:  %s\n", commatize(fgTotalRebaseFixups, commaNum1));
+       printTime("  total rebase fixups time", fgTotalRebaseTime, totalTime);
+       dyld::log("  total binding fixups: %s\n", commatize(fgTotalBindFixups, commaNum1));
        if ( fgTotalBindSymbolsResolved != 0 ) {
                uint32_t avgTimesTen = (fgTotalBindImageSearches * 10) / fgTotalBindSymbolsResolved;
                uint32_t avgInt = fgTotalBindImageSearches / fgTotalBindSymbolsResolved;
@@ -897,10 +1307,21 @@ void ImageLoader::printStatistics(unsigned int imageCount)
                dyld::log("total binding symbol lookups: %s, average images searched per symbol: %u.%u\n", 
                                commatize(fgTotalBindSymbolsResolved, commaNum1), avgInt, avgTenths);
        }
-       printTime("total binding fixups time", fgTotalBindTime, totalTime);
-       printTime("total weak binding fixups time", fgTotalWeakBindTime, totalTime);
-       dyld::log("total bindings lazily fixed up: %s of %s\n", commatize(fgTotalLazyBindFixups, commaNum1), commatize(fgTotalPossibleLazyBindFixups, commaNum2));
-       printTime("total initializer time", fgTotalInitTime, totalTime);
+       printTime("  total binding fixups time", fgTotalBindTime, totalTime);
+       printTime("  total weak binding fixups time", fgTotalWeakBindTime, totalTime);
+       printTime("  total redo shared cached bindings time", fgTotalRebindCacheTime, totalTime);
+       dyld::log("  total bindings lazily fixed up: %s of %s\n", commatize(fgTotalLazyBindFixups, commaNum1), commatize(fgTotalPossibleLazyBindFixups, commaNum2));
+       printTime("  total time in initializers and ObjC +load", fgTotalInitTime-fgTotalObjCSetupTime, totalTime);
+       for (uintptr_t i=0; i < timingInfo.count; ++i) {
+               uint64_t t = timingInfo.images[i].initTime;
+               if ( t*1000 < totalTime )
+                       continue;
+               dyld::log("%42s ", timingInfo.images[i].shortName);
+               if ( strncmp(timingInfo.images[i].shortName, "libSystem.", 10) == 0 )
+                       t -= fgTotalObjCSetupTime;
+               printTime("", t, totalTime);
+       }
+       
 }
 
 
@@ -934,5 +1355,130 @@ void ImageLoader::addSuffix(const char* path, const char* suffix, char* result)
 }
 
 
+//
+// This function is the hotspot of symbol lookup.  It was pulled out of findExportedSymbol()
+// to enable it to be re-written in assembler if needed.
+//
+const uint8_t* ImageLoader::trieWalk(const uint8_t* start, const uint8_t* end, const char* s)
+{
+       //dyld::log("trieWalk(%p, %p, %s)\n", start, end, s);
+       ++fgSymbolTrieSearchs;
+       const uint8_t* p = start;
+       while ( p != NULL ) {
+               uintptr_t terminalSize = *p++;
+               if ( terminalSize > 127 ) {
+                       // except for re-export-with-rename, all terminal sizes fit in one byte
+                       --p;
+                       terminalSize = read_uleb128(p, end);
+               }
+               if ( (*s == '\0') && (terminalSize != 0) ) {
+                       //dyld::log("trieWalk(%p) returning %p\n", start, p);
+                       return p;
+               }
+               const uint8_t* children = p + terminalSize;
+               if ( children > end ) {
+                       dyld::log("trieWalk() malformed trie node, terminalSize=0x%lx extends past end of trie\n", terminalSize);
+                       return NULL;
+               }
+               //dyld::log("trieWalk(%p) sym=%s, terminalSize=%lu, children=%p\n", start, s, terminalSize, children);
+               uint8_t childrenRemaining = *children++;
+               p = children;
+               uintptr_t nodeOffset = 0;
+               for (; childrenRemaining > 0; --childrenRemaining) {
+                       const char* ss = s;
+                       //dyld::log("trieWalk(%p) child str=%s\n", start, (char*)p);
+                       bool wrongEdge = false;
+                       // scan whole edge to get to next edge
+                       // if edge is longer than target symbol name, don't read past end of symbol name
+                       char c = *p;
+                       while ( c != '\0' ) {
+                               if ( !wrongEdge ) {
+                                       if ( c != *ss )
+                                               wrongEdge = true;
+                                       ++ss;
+                               }
+                               ++p;
+                               c = *p;
+                       }
+                       if ( wrongEdge ) {
+                               // advance to next child
+                               ++p; // skip over zero terminator
+                               // skip over uleb128 until last byte is found
+                               while ( (*p & 0x80) != 0 )
+                                       ++p;
+                               ++p; // skip over last byte of uleb128
+                               if ( p > end ) {
+                                       dyld::log("trieWalk() malformed trie node, child node extends past end of trie\n");
+                                       return NULL;
+                               }
+                       }
+                       else {
+                               // the symbol so far matches this edge (child)
+                               // so advance to the child's node
+                               ++p;
+                               nodeOffset = read_uleb128(p, end);
+                               if ( (nodeOffset == 0) || ( &start[nodeOffset] > end) ) {
+                                       dyld::log("trieWalk() malformed trie child, nodeOffset=0x%lx out of range\n", nodeOffset);
+                                       return NULL;
+                               }
+                               s = ss;
+                               //dyld::log("trieWalk() found matching edge advancing to node 0x%lx\n", nodeOffset);
+                               break;
+                       }
+               }
+               if ( nodeOffset != 0 )
+                       p = &start[nodeOffset];
+               else
+                       p = NULL;
+       }
+       //dyld::log("trieWalk(%p) return NULL\n", start);
+       return NULL;
+}
+
+
+       
+uintptr_t ImageLoader::read_uleb128(const uint8_t*& p, const uint8_t* end)
+{
+       uint64_t result = 0;
+       int              bit = 0;
+       do {
+               if (p == end)
+                       dyld::throwf("malformed uleb128");
+
+               uint64_t slice = *p & 0x7f;
+
+               if (bit > 63)
+                       dyld::throwf("uleb128 too big for uint64, bit=%d, result=0x%0llX", bit, result);
+               else {
+                       result |= (slice << bit);
+                       bit += 7;
+               }
+       } while (*p++ & 0x80);
+       return (uintptr_t)result;
+}
+
+
+intptr_t ImageLoader::read_sleb128(const uint8_t*& p, const uint8_t* end)
+{
+       int64_t result = 0;
+       int bit = 0;
+       uint8_t byte;
+       do {
+               if (p == end)
+                       throw "malformed sleb128";
+               byte = *p++;
+               result |= (((int64_t)(byte & 0x7f)) << bit);
+               bit += 7;
+       } while (byte & 0x80);
+       // sign extend negative numbers
+       if ( (byte & 0x40) != 0 )
+               result |= (~0ULL) << bit;
+       return (intptr_t)result;
+}
+
+
+VECTOR_NEVER_DESTRUCTED_IMPL(ImageLoader::InterposeTuple);
+VECTOR_NEVER_DESTRUCTED_IMPL(ImagePair);
+