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--- dyld/dyld-46.9/src/ImageLoaderMachO.cpp
+++ dyld/dyld-46.16/src/ImageLoaderMachO.cpp
@@ -1299,7 +1299,14 @@
++fgImagesWithUsedPrebinding; // bump totals for statistics
return;
}
-
+
+ // <rdar://problem/5146059> update_prebinding fails if a prebound dylib depends on a non-prebound dylib
+ // In the unusual case that we find a prebound dylib dependent on un-prebound dylib and we are running
+ // update_prebinding, we want the link of the prebound dylib to fail so that it will be excluded from
+ // the list of dylibs to be re-written.
+ if ( context.prebinding && !this->isPrebindable() )
+ throwf("dylib not prebound: %s", this->getPath());
+
// print why prebinding was not used
if ( context.verbosePrebinding ) {
if ( !this->isPrebindable() ) {
@@ -1397,12 +1404,16 @@
otherRelocsPPC(locationToFix, sreloc->r_type, reloc->r_address, slide);
break;
#endif
- #if __ppc__ || __ppc64__
+ #if __ppc__
case PPC_RELOC_PB_LA_PTR:
// do nothing
break;
- #endif
- #if __i386__
+ #elif __ppc64__
+ case PPC_RELOC_PB_LA_PTR:
+ // these should never exist in ppc64, but the first ld64 had a bug and created them
+ *locationToFix = sreloc->r_value + slide;
+ break;
+ #elif __i386__
case GENERIC_RELOC_PB_LA_PTR:
// do nothing
break;
@@ -1752,6 +1763,12 @@
if ( context.bindFlat || !twoLevel ) {
// flat lookup
+ if ( ((undefinedSymbol->n_type & N_PEXT) != 0) && ((undefinedSymbol->n_type & N_TYPE) == N_SECT) ) {
+ // is a multi-module private_extern internal reference that the linker did not optimize away
+ uintptr_t addr = undefinedSymbol->n_value + this->fSlide;
+ *foundIn = this;
+ return addr;
+ }
const Symbol* sym;
if ( context.flatExportFinder(symbolName, &sym, foundIn) )
return (*foundIn)->getExportedSymbolAddress(sym);
@@ -1762,13 +1779,6 @@
if ( sym != NULL )
return (*foundIn)->getExportedSymbolAddress(sym);
}
- if ( ((undefinedSymbol->n_type & N_PEXT) != 0) || ((undefinedSymbol->n_type & N_TYPE) == N_SECT) ) {
- // could be a multi-module private_extern internal reference
- // the static linker squirrels away the target address in n_value
- uintptr_t addr = undefinedSymbol->n_value + this->fSlide;
- *foundIn = this;
- return addr;
- }
if ( (undefinedSymbol->n_desc & N_WEAK_REF) != 0 ) {
// definition can't be found anywhere
// if reference is weak_import, then it is ok, just return 0
@@ -1778,7 +1788,7 @@
}
else {
// symbol requires searching images with coalesced symbols
- if ( this->needsCoalescing() && symbolRequiresCoalescing(undefinedSymbol) ) {
+ if ( !context.prebinding && this->needsCoalescing() && symbolRequiresCoalescing(undefinedSymbol) ) {
const Symbol* sym;
if ( context.coalescedExportFinder(symbolName, &sym, foundIn) )
return (*foundIn)->getExportedSymbolAddress(sym);
@@ -1824,7 +1834,7 @@
}
if ( target == NULL ) {
- fprintf(stderr, "resolveUndefined(%s) in %s\n", symbolName, this->getPath());
+ //fprintf(stderr, "resolveUndefined(%s) in %s\n", symbolName, this->getPath());
throw "symbol not found";
}
@@ -2302,16 +2312,49 @@
const uint8_t type = sect->flags & SECTION_TYPE;
if ( (type == S_SYMBOL_STUBS) && (sect->flags & S_ATTR_SELF_MODIFYING_CODE) && (sect->reserved2 == 5) ) {
// reset each jmp entry in this section
+ const uint32_t indirectTableOffset = sect->reserved1;
+ const uint32_t* const indirectTable = (uint32_t*)&fLinkEditBase[fDynamicInfo->indirectsymoff];
uint8_t* start = (uint8_t*)(sect->addr + this->fSlide);
uint8_t* end = start + sect->size;
uintptr_t dyldHandler = (uintptr_t)&fast_stub_binding_helper_interface;
- for (uint8_t* entry = start; entry < end; entry += 5) {
- uint32_t rel32 = dyldHandler - (((uint32_t)entry)+5);
- entry[0] = 0xE8; // CALL rel32
- entry[1] = rel32 & 0xFF;
- entry[2] = (rel32 >> 8) & 0xFF;
- entry[3] = (rel32 >> 16) & 0xFF;
- entry[4] = (rel32 >> 24) & 0xFF;
+ uint32_t entryIndex = 0;
+ for (uint8_t* entry = start; entry < end; entry += 5, ++entryIndex) {
+ bool installLazyHandler = true;
+ // jump table entries that cross a (64-byte) cache line boundary have the potential to cause crashes
+ // if the instruction is updated by one thread while being executed by another
+ if ( ((uint32_t)entry & 0xFFFFFFC0) != ((uint32_t)entry+4 & 0xFFFFFFC0) ) {
+ // need to bind this now to avoid a potential problem if bound lazily
+ uint32_t symbolIndex = indirectTable[indirectTableOffset + entryIndex];
+ // the latest linker marks 64-byte crossing stubs with INDIRECT_SYMBOL_ABS so they are not used
+ if ( symbolIndex != INDIRECT_SYMBOL_ABS ) {
+ const char* symbolName = &fStrings[fSymbolTable[symbolIndex].n_un.n_strx];
+ ImageLoader* image = NULL;
+ try {
+ uintptr_t symbolAddr = this->resolveUndefined(context, &fSymbolTable[symbolIndex], this->usesTwoLevelNameSpace(), &image);
+ symbolAddr = this->bindIndirectSymbol((uintptr_t*)entry, sect, symbolName, symbolAddr, image, context);
+ ++fgTotalBindFixups;
+ uint32_t rel32 = symbolAddr - (((uint32_t)entry)+5);
+ entry[0] = 0xE9; // JMP rel32
+ entry[1] = rel32 & 0xFF;
+ entry[2] = (rel32 >> 8) & 0xFF;
+ entry[3] = (rel32 >> 16) & 0xFF;
+ entry[4] = (rel32 >> 24) & 0xFF;
+ installLazyHandler = false;
+ }
+ catch (const char* msg) {
+ // ignore errors when binding symbols early
+ // maybe the function is never called, and therefore erroring out now would be a regression
+ }
+ }
+ }
+ if ( installLazyHandler ) {
+ uint32_t rel32 = dyldHandler - (((uint32_t)entry)+5);
+ entry[0] = 0xE8; // CALL rel32
+ entry[1] = rel32 & 0xFF;
+ entry[2] = (rel32 >> 8) & 0xFF;
+ entry[3] = (rel32 >> 16) & 0xFF;
+ entry[4] = (rel32 >> 24) & 0xFF;
+ }
}
}
}
@@ -2326,7 +2369,10 @@
bool ImageLoaderMachO::usablePrebinding(const LinkContext& context) const
{
// if prebound and loaded at prebound address, and all libraries are same as when this was prebound, then no need to bind
- if ( this->isPrebindable() && this->allDependentLibrariesAsWhenPreBound() && (this->getSlide() == 0) ) {
+ if ( this->isPrebindable()
+ && (this->getSlide() == 0)
+ && (this->usesTwoLevelNameSpace() || context.prebinding)
+ && this->allDependentLibrariesAsWhenPreBound() ) {
// allow environment variables to disable prebinding
if ( context.bindFlat )
return false;
@@ -2505,16 +2551,22 @@
for (const DependentLibrary* dl=fLibraries; dl < &fLibraries[fLibrariesCount]; dl++) {
if (strcmp(dl->name, name) == 0 ) {
// found matching DependentLibrary for this load command
- ImageLoaderMachO* targetImage = (ImageLoaderMachO*)(dl->image); // !!! assume only mach-o images are prebound
- if ( ! targetImage->isPrebindable() )
- throw "dependent dylib is not prebound";
- // if the target is currently being re-prebound then its timestamp will be the same as this one
- if ( ! targetImage->usablePrebinding(context) ) {
- dylib->dylib.timestamp = timestamp;
+ if ( dl->image == NULL ) {
+ // missing weak linked dylib
+ dylib->dylib.timestamp = 0;
}
else {
- // otherwise dependent library is already correctly prebound, so use its checksum
- dylib->dylib.timestamp = targetImage->doGetLibraryInfo().checksum;
+ ImageLoaderMachO* targetImage = (ImageLoaderMachO*)(dl->image); // !!! assume only mach-o images are prebound
+ if ( ! targetImage->isPrebindable() )
+ throw "dependent dylib is not prebound";
+ // if the target is currently being re-prebound then its timestamp will be the same as this one
+ if ( ! targetImage->usablePrebinding(context) ) {
+ dylib->dylib.timestamp = timestamp;
+ }
+ else {
+ // otherwise dependent library is already correctly prebound, so use its checksum
+ dylib->dylib.timestamp = targetImage->doGetLibraryInfo().checksum;
+ }
}
break;
}