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--- dyld/dyld-43/src/ImageLoaderMachO.cpp
+++ dyld/dyld-46.12/src/ImageLoaderMachO.cpp
@@ -34,8 +34,16 @@
#include <mach-o/reloc.h>
#include <mach-o/nlist.h>
#include <sys/sysctl.h>
+#include <libkern/OSAtomic.h>
#if __ppc__ || __ppc64__
#include <mach-o/ppc/reloc.h>
+#endif
+#if __x86_64__
+ #include <mach-o/x86_64/reloc.h>
+#endif
+
+#ifndef S_ATTR_SELF_MODIFYING_CODE
+ #define S_ATTR_SELF_MODIFYING_CODE 0x04000000
#endif
#include "ImageLoaderMachO.h"
@@ -72,9 +80,15 @@
struct macho_routines_command : public routines_command {};
#endif
+#if __x86_64__
+ #define POINTER_RELOC X86_64_RELOC_UNSIGNED
+#else
+ #define POINTER_RELOC GENERIC_RELOC_VANILLA
+#endif
uint32_t ImageLoaderMachO::fgHintedBinaryTreeSearchs = 0;
uint32_t ImageLoaderMachO::fgUnhintedBinaryTreeSearchs = 0;
+uint32_t ImageLoaderMachO::fgCountOfImagesWithWeakExports = 0;
//#define LINKEDIT_USAGE_DEBUG 1
@@ -176,6 +190,12 @@
this->parseLoadCmds();
}
+ImageLoaderMachO::~ImageLoaderMachO()
+{
+ // keep count of images with weak exports
+ if ( this->hasCoalescedExports() )
+ --fgCountOfImagesWithWeakExports;
+}
@@ -188,7 +208,8 @@
const struct load_command* cmd = cmds;
for (unsigned long i = 0; i < cmd_count; ++i) {
if ( cmd->cmd == LC_SEGMENT_COMMAND ) {
- fSegments.push_back(new SegmentMachO((struct macho_segment_command*)cmd, this, fileData));
+ if ( (((struct macho_segment_command*)cmd)->vmsize != 0) || !fIsSplitSeg )
+ fSegments.push_back(new SegmentMachO((struct macho_segment_command*)cmd, this, fileData));
}
cmd = (const struct load_command*)(((char*)cmd)+cmd->cmdsize);
}
@@ -316,6 +337,38 @@
= 0;
#endif
+static int
+_shared_region_map_file_with_mmap(
+ int fd, // file descriptor to map into shared region
+ unsigned int regionCount, // number of entres in array of regions
+ const _shared_region_mapping_np regions[]) // the array of regions to map
+{
+ // map in each region
+ for(unsigned int i=0; i < regionCount; ++i) {
+ void* mmapAddress = (void*)(uintptr_t)(regions[i].address);
+ size_t size = regions[i].size;
+ if ( (regions[i].init_prot & VM_PROT_ZF) != 0 ) {
+ // do nothing already vm_allocate() which zero fills
+ }
+ else {
+ int protection = 0;
+ if ( regions[i].init_prot & VM_PROT_EXECUTE )
+ protection |= PROT_EXEC;
+ if ( regions[i].init_prot & VM_PROT_READ )
+ protection |= PROT_READ;
+ if ( regions[i].init_prot & VM_PROT_WRITE )
+ protection |= PROT_WRITE;
+ off_t offset = regions[i].file_offset;
+ //fprintf(stderr, "mmap(%p, 0x%08lX, block=0x%08X, %s\n", mmapAddress, size, biggestDiff, fPath);
+ mmapAddress = mmap(mmapAddress, size, protection, MAP_FILE | MAP_FIXED | MAP_PRIVATE, fd, offset);
+ if ( mmapAddress == ((void*)(-1)) )
+ throw "mmap error";
+ }
+ }
+
+ return 0;
+}
+
static
bool
@@ -366,6 +419,8 @@
}
sNextAltLoadAddress += 0x00100000; // skip ahead 1MB and try again
if ( (sNextAltLoadAddress & 0xF0000000) == 0x90000000 )
+ sNextAltLoadAddress = 0xB0000000;
+ if ( (sNextAltLoadAddress & 0xF0000000) == 0xF0000000 )
throw "can't map split seg anywhere";
foundRoom = false;
break;
@@ -437,6 +492,7 @@
kSharedRegionLoadFileState,
kSharedRegionMapFileState,
kSharedRegionMapFilePrivateState,
+ kSharedRegionMapFilePrivateMMapState,
kSharedRegionMapFilePrivateOutsideState,
};
static SharedRegionState sSharedRegionState = kSharedRegionStartState;
@@ -447,7 +503,15 @@
if ( kSharedRegionStartState == sSharedRegionState ) {
if ( hasSharedRegionMapFile() ) {
- if ( (context.sharedRegionMode == kUsePrivateSharedRegion) || context.slideAndPackDylibs ) {
+ if ( context.slideAndPackDylibs ) {
+ sharedRegionMakePrivate(context);
+ // remove underlying submap and block out 0x90000000 to 0xAFFFFFFF
+ vm_address_t addr = (vm_address_t)0x90000000;
+ vm_deallocate(mach_task_self(), addr, 0x20000000);
+ vm_allocate(mach_task_self(), &addr, 0x20000000, false);
+ sSharedRegionState = kSharedRegionMapFilePrivateMMapState;
+ }
+ else if ( context.sharedRegionMode == kUsePrivateSharedRegion ) {
sharedRegionMakePrivate(context);
sSharedRegionState = kSharedRegionMapFilePrivateState;
}
@@ -476,8 +540,8 @@
}
}
- if ( kSharedRegionMapFilePrivateState == sSharedRegionState ) {
- if ( 0 != sharedRegionMapFilePrivate(fd, offsetInFat, lenInFat, fileLen, context) ) {
+ if ( (kSharedRegionMapFilePrivateState == sSharedRegionState) || (kSharedRegionMapFilePrivateMMapState == sSharedRegionState) ) {
+ if ( 0 != sharedRegionMapFilePrivate(fd, offsetInFat, lenInFat, fileLen, context, (kSharedRegionMapFilePrivateMMapState == sSharedRegionState)) ) {
sSharedRegionState = kSharedRegionMapFilePrivateOutsideState;
}
}
@@ -608,12 +672,14 @@
return r;
}
+
int
ImageLoaderMachO::sharedRegionMapFilePrivate(int fd,
uint64_t offsetInFat,
uint64_t lenInFat,
uint64_t fileLen,
- const LinkContext& context)
+ const LinkContext& context,
+ bool usemmap)
{
const unsigned int segmentCount = fSegments.size();
@@ -650,7 +716,11 @@
uint64_t slide = 0;
// try map it in privately (don't allow sliding if we pre-calculated the load address to pack dylibs)
- int r = _shared_region_map_file_np(fd, mappingTableCount, mappingTable, context.slideAndPackDylibs ? NULL : &slide);
+ int r;
+ if ( usemmap )
+ r = _shared_region_map_file_with_mmap(fd, mappingTableCount, mappingTable);
+ else
+ r = _shared_region_map_file_np(fd, mappingTableCount, mappingTable, context.slideAndPackDylibs ? NULL : &slide);
if ( 0 == r ) {
if ( 0 != slide ) {
slide = (slide) & (-4096); // round down to page boundary
@@ -702,7 +772,7 @@
}
}
if ( context.slideAndPackDylibs && (r != 0) )
- throw "can't rebase split-seg dylib";
+ throwf("can't rebase split-seg dylib %s because shared_region_map_file_np() returned %d", this->getPath(), r);
return r;
}
@@ -848,6 +918,10 @@
}
}
+ // keep count of prebound images with weak exports
+ if ( this->hasCoalescedExports() )
+ ++fgCountOfImagesWithWeakExports;
+
// walk load commands (mapped in at start of __TEXT segment)
const uint32_t cmd_count = ((macho_header*)fMachOData)->ncmds;
const struct load_command* const cmds = (struct load_command*)&fMachOData[sizeof(macho_header)];
@@ -891,8 +965,9 @@
fModInitSection = sect;
else if ( type == S_MOD_TERM_FUNC_POINTERS )
fModTermSection = sect;
- else if ( isDataSeg && (strcmp(sect->sectname, "__dyld") == 0) )
- fDATAdyld = sect;
+ else if ( isDataSeg && (strcmp(sect->sectname, "__dyld") == 0) ) {
+ fDATAdyld = sect;
+ }
else if ( isDataSeg && (strcmp(sect->sectname, "__image_notify") == 0) )
fImageNotifySection = sect;
}
@@ -906,6 +981,12 @@
fDylibID = (struct dylib_command*)cmd;
}
break;
+ case LC_LOAD_WEAK_DYLIB:
+ // do nothing, just prevent LC_REQ_DYLD exception from occuring
+ break;
+ default:
+ if ( (cmd->cmd & LC_REQ_DYLD) != 0 )
+ throwf("unknown required load command 0x%08X", cmd->cmd);
}
cmd = (const struct load_command*)(((char*)cmd)+cmd->cmdsize);
}
@@ -1047,6 +1128,9 @@
#elif __i386__
const i386_thread_state_t* registers = (i386_thread_state_t*)(((char*)cmd) + 16);
return (void*)registers->eip;
+ #elif __x86_64__
+ const x86_thread_state64_t* registers = (x86_thread_state64_t*)(((char*)cmd) + 16);
+ return (void*)registers->rip;
#else
#warning need processor specific code
#endif
@@ -1122,19 +1206,29 @@
return info;
}
+uintptr_t ImageLoaderMachO::getFirstWritableSegmentAddress()
+{
+ // in split segment libraries r_address is offset from first writable segment
+ for (std::vector<class Segment*>::iterator it=fSegments.begin(); it != fSegments.end(); ++it) {
+ if ( (*it)->writeable() ) {
+ return (*it)->getActualLoadAddress();
+ }
+ }
+ throw "no writable segment";
+}
uintptr_t ImageLoaderMachO::getRelocBase()
{
+#if __x86_64__
+ // r_address is offset from first writable segment
+ return getFirstWritableSegmentAddress();
+#endif
+#if __ppc__ || __i386__
if ( fIsSplitSeg ) {
// in split segment libraries r_address is offset from first writable segment
- const unsigned int segmentCount = fSegments.size();
- for(unsigned int i=0; i < segmentCount; ++i){
- Segment* seg = fSegments[i];
- if ( seg->writeable() ) {
- return seg->getActualLoadAddress();
- }
- }
- }
+ return getFirstWritableSegmentAddress();
+ }
+#endif
// in non-split segment libraries r_address is offset from first segment
return fSegments[0]->getActualLoadAddress();
@@ -1167,14 +1261,40 @@
}
#endif
+#if __ppc__ || __i386__
+void ImageLoaderMachO::resetPreboundLazyPointers(const LinkContext& context, uintptr_t relocBase)
+{
+ // loop through all local (internal) relocation records looking for pre-bound-lazy-pointer values
+ register const uintptr_t slide = this->fSlide;
+ const relocation_info* const relocsStart = (struct relocation_info*)(&fLinkEditBase[fDynamicInfo->locreloff]);
+ const relocation_info* const relocsEnd = &relocsStart[fDynamicInfo->nlocrel];
+ for (const relocation_info* reloc=relocsStart; reloc < relocsEnd; ++reloc) {
+ if ( (reloc->r_address & R_SCATTERED) != 0 ) {
+ const struct scattered_relocation_info* sreloc = (struct scattered_relocation_info*)reloc;
+ if (sreloc->r_length == RELOC_SIZE) {
+ uintptr_t* locationToFix = (uintptr_t*)(sreloc->r_address + relocBase);
+ switch(sreloc->r_type) {
+ #if __ppc__
+ case PPC_RELOC_PB_LA_PTR:
+ *locationToFix = sreloc->r_value + slide;
+ break;
+ #endif
+ #if __i386__
+ case GENERIC_RELOC_PB_LA_PTR:
+ *locationToFix = sreloc->r_value + slide;
+ break;
+ #endif
+ }
+ }
+ }
+ }
+}
+#endif
+
void ImageLoaderMachO::doRebase(const LinkContext& context)
{
// if prebound and loaded at prebound address, then no need to rebase
- // Note: you might think that the check for allDependentLibrariesAsWhenPreBound() is not needed
- // but it is. If a dependent library changed, this image's lazy pointers into that library
- // need to be updated (reset back to lazy binding handler). That work is done most easily
- // here because there is a PPC_RELOC_PB_LA_PTR reloc record for each lazy pointer.
- if ( this->usablePrebinding(context) && this->usesTwoLevelNameSpace() ) {
+ if ( this->usablePrebinding(context) ) {
// skip rebasing cause prebound and prebinding not disabled
++fgImagesWithUsedPrebinding; // bump totals for statistics
return;
@@ -1199,18 +1319,41 @@
}
}
+ // cache values that are used in the following loop
+ const uintptr_t relocBase = this->getRelocBase();
+ register const uintptr_t slide = this->fSlide;
+
+#if __ppc__ || __i386__
+ // if prebound and we got here, then prebinding is not valid, so reset all lazy pointers
+ if ( this->isPrebindable() )
+ this->resetPreboundLazyPointers(context, relocBase);
+#endif
+
+ // if loaded at preferred address, no rebasing necessary
+ if ( slide == 0 )
+ return;
+
// if there are __TEXT fixups, temporarily make __TEXT writable
if ( fTextSegmentWithFixups != NULL )
fTextSegmentWithFixups->tempWritable();
- // cache this value that is used in the following loop
- register const uintptr_t slide = this->fSlide;
-
// loop through all local (internal) relocation records
- const uintptr_t relocBase = this->getRelocBase();
const relocation_info* const relocsStart = (struct relocation_info*)(&fLinkEditBase[fDynamicInfo->locreloff]);
const relocation_info* const relocsEnd = &relocsStart[fDynamicInfo->nlocrel];
for (const relocation_info* reloc=relocsStart; reloc < relocsEnd; ++reloc) {
+ #if __x86_64__
+ // only one kind of local relocation supported for x86_64
+ if ( reloc->r_length != 3 )
+ throw "bad local relocation length";
+ if ( reloc->r_type != X86_64_RELOC_UNSIGNED )
+ throw "unknown local relocation type";
+ if ( reloc->r_pcrel != 0 )
+ throw "bad local relocation pc_rel";
+ if ( reloc->r_extern != 0 )
+ throw "extern relocation found with local relocations";
+ *((uintptr_t*)(reloc->r_address + relocBase)) += slide;
+ #endif
+ #if __ppc__ || __ppc64__ || __i386__
if ( (reloc->r_address & R_SCATTERED) == 0 ) {
if ( reloc->r_symbolnum == R_ABS ) {
// ignore absolute relocations
@@ -1245,12 +1388,6 @@
case GENERIC_RELOC_VANILLA:
*locationToFix += slide;
break;
- #if __ppc__ || __ppc64__
- case PPC_RELOC_PB_LA_PTR:
- // should only see these in prebound images, and we got here so prebinding is being ignored
- *locationToFix = sreloc->r_value + slide;
- break;
- #endif
#if __ppc__
case PPC_RELOC_HI16:
case PPC_RELOC_LO16:
@@ -1260,10 +1397,18 @@
otherRelocsPPC(locationToFix, sreloc->r_type, reloc->r_address, slide);
break;
#endif
- #if __i386__
+ #if __ppc__
+ case PPC_RELOC_PB_LA_PTR:
+ // do nothing
+ break;
+ #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:
- // should only see these in prebound images, and we got here so prebinding is being ignored
- *locationToFix = sreloc->r_value + slide;
+ // do nothing
break;
#endif
default:
@@ -1274,6 +1419,7 @@
throw "bad local scattered relocation length";
}
}
+ #endif
}
// if there were __TEXT fixups, restore write protection
@@ -1443,6 +1589,7 @@
}
}
+
return NULL;
}
@@ -1609,6 +1756,12 @@
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);
@@ -1618,13 +1771,6 @@
sym = this->findExportedSymbol(symbolName, NULL, false, foundIn);
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
@@ -1715,6 +1861,34 @@
}
}
+// returns if 'addr' is within the address range of section 'sectionIndex'
+// fSlide is not used. 'addr' is assumed to be a prebound address in this image
+bool ImageLoaderMachO::isAddrInSection(uintptr_t addr, uint8_t sectionIndex)
+{
+ uint8_t currentSectionIndex = 1;
+ const uint32_t cmd_count = ((macho_header*)fMachOData)->ncmds;
+ const struct load_command* const cmds = (struct load_command*)&fMachOData[sizeof(macho_header)];
+ const struct load_command* cmd = cmds;
+ for (unsigned long i = 0; i < cmd_count; ++i) {
+ if ( cmd->cmd == LC_SEGMENT_COMMAND ) {
+ const struct macho_segment_command* seg = (struct macho_segment_command*)cmd;
+ if ( (currentSectionIndex <= sectionIndex) && (sectionIndex < currentSectionIndex+seg->nsects) ) {
+ // 'sectionIndex' is in this segment, get section info
+ const struct macho_section* const sectionsStart = (struct macho_section*)((char*)seg + sizeof(struct macho_segment_command));
+ const struct macho_section* const section = §ionsStart[sectionIndex-currentSectionIndex];
+ return ( (section->addr <= addr) && (addr < section->addr+section->size) );
+ }
+ else {
+ // 'sectionIndex' not in this segment, skip to next segment
+ currentSectionIndex += seg->nsects;
+ }
+ }
+ cmd = (const struct load_command*)(((char*)cmd)+cmd->cmdsize);
+ }
+
+ return false;
+}
+
void ImageLoaderMachO::doBindExternalRelocations(const LinkContext& context, bool onlyCoalescedSymbols)
{
const uintptr_t relocBase = this->getRelocBase();
@@ -1736,7 +1910,7 @@
for (const relocation_info* reloc=relocsStart; reloc < relocsEnd; ++reloc) {
if (reloc->r_length == RELOC_SIZE) {
switch(reloc->r_type) {
- case GENERIC_RELOC_VANILLA:
+ case POINTER_RELOC:
{
const struct macho_nlist* undefinedSymbol = &fSymbolTable[reloc->r_symbolnum];
// if only processing coalesced symbols and this one does not require coalesceing, skip to next
@@ -1744,12 +1918,31 @@
continue;
uintptr_t* location = ((uintptr_t*)(reloc->r_address + relocBase));
uintptr_t value = *location;
+ #if __i386__
+ if ( reloc->r_pcrel ) {
+ value += (uintptr_t)location + 4 - fSlide;
+ }
+ #endif
if ( prebound ) {
// we are doing relocations, so prebinding was not usable
- // in a prebound executable, the n_value field is set to the address where the symbol was found when prebound
+ // in a prebound executable, the n_value field of an undefined symbol is set to the address where the symbol was found when prebound
// so, subtracting that gives the initial displacement which we need to add to the newly found symbol address
- // if mach-o relocation structs had an "addend" field this would not be necessary.
- value -= undefinedSymbol->n_value;
+ // if mach-o relocation structs had an "addend" field this complication would not be necessary.
+ if ( ((undefinedSymbol->n_type & N_TYPE) == N_SECT) && ((undefinedSymbol->n_desc & N_WEAK_DEF) != 0) ) {
+ // weak symbols need special casing, since *location may have been prebound to a definition in another image.
+ // If *location is currently prebound to somewhere in the same section as the weak definition, we assume
+ // that we can subtract off the weak symbol address to get the addend.
+ // If prebound elsewhere, we've lost the addend and have to assume it is zero.
+ // The prebinding to elsewhere only happens with 10.4+ update_prebinding which only operates on a small set of Apple dylibs
+ if ( (value == undefinedSymbol->n_value) || this->isAddrInSection(value, undefinedSymbol->n_sect) )
+ value -= undefinedSymbol->n_value;
+ else
+ value = 0;
+ }
+ else {
+ // is undefined or non-weak symbol, so do subtraction to get addend
+ value -= undefinedSymbol->n_value;
+ }
}
// if undefinedSymbol is same as last time, then symbolAddr and image will resolve to the same too
if ( undefinedSymbol != lastUndefinedSymbol ) {
@@ -1773,7 +1966,20 @@
}
}
value += symbolAddr;
- *location = value;
+ #if __i386__
+ if ( reloc->r_pcrel ) {
+ *location = value - ((uintptr_t)location + 4);
+ }
+ else {
+ // don't dirty page if prebound value was correct
+ if ( !prebound || (*location != value) )
+ *location = value;
+ }
+ #else
+ // don't dirty page if prebound value was correct
+ if ( !prebound || (*location != value) )
+ *location = value;
+ #endif
}
break;
default:
@@ -1810,6 +2016,61 @@
{
Segment* seg = fSegments[0];
return (const void*)seg->getActualLoadAddress();
+}
+
+uintptr_t ImageLoaderMachO::bindIndirectSymbol(uintptr_t* ptrToBind, const struct macho_section* sect, const char* symbolName, uintptr_t targetAddr, ImageLoader* targetImage, const LinkContext& context)
+{
+ if ( context.verboseBind ) {
+ const char* path = NULL;
+ if ( targetImage != NULL )
+ path = targetImage->getShortName();
+ fprintf(stderr, "dyld: bind: %s:%s$%s = %s:%s, *0x%08lx = 0x%08lx\n",
+ this->getShortName(), symbolName, (((sect->flags & SECTION_TYPE)==S_NON_LAZY_SYMBOL_POINTERS) ? "non_lazy_ptr" : "lazy_ptr"),
+ path, symbolName, (uintptr_t)ptrToBind, targetAddr);
+ }
+ if ( context.bindingHandler != NULL ) {
+ const char* path = NULL;
+ if ( targetImage != NULL )
+ path = targetImage->getShortName();
+ targetAddr = (uintptr_t)context.bindingHandler(path, symbolName, (void *)targetAddr);
+ }
+#if __i386__
+ // i386 has special self-modifying stubs that change from "CALL rel32" to "JMP rel32"
+ if ( ((sect->flags & SECTION_TYPE) == S_SYMBOL_STUBS) && ((sect->flags & S_ATTR_SELF_MODIFYING_CODE) != 0) && (sect->reserved2 == 5) ) {
+ uint32_t rel32 = targetAddr - (((uint32_t)ptrToBind)+5);
+ // re-write instruction in a thread-safe manner
+ // use 8-byte compare-and-swap to alter 5-byte jump table entries
+ // loop is required in case the extra three bytes that cover the next entry are altered by another thread
+ bool done = false;
+ while ( !done ) {
+ volatile int64_t* jumpPtr = (int64_t*)ptrToBind;
+ int pad = 0;
+ // By default the three extra bytes swapped follow the 5-byte JMP.
+ // But, if the 5-byte jump is up against the end of the __IMPORT segment
+ // We don't want to access bytes off the end of the segment, so we shift
+ // the extra bytes to precede the 5-byte JMP.
+ if ( (((uint32_t)ptrToBind + 8) & 0x00000FFC) == 0x00000000 ) {
+ jumpPtr = (int64_t*)((uint32_t)ptrToBind - 3);
+ pad = 3;
+ }
+ int64_t oldEntry = *jumpPtr;
+ union {
+ int64_t int64;
+ uint8_t bytes[8];
+ } newEntry;
+ newEntry.int64 = oldEntry;
+ newEntry.bytes[pad+0] = 0xE9; // JMP rel32
+ newEntry.bytes[pad+1] = rel32 & 0xFF;
+ newEntry.bytes[pad+2] = (rel32 >> 8) & 0xFF;
+ newEntry.bytes[pad+3] = (rel32 >> 16) & 0xFF;
+ newEntry.bytes[pad+4] = (rel32 >> 24) & 0xFF;
+ done = OSAtomicCompareAndSwap64Barrier(oldEntry, newEntry.int64, (int64_t*)jumpPtr);
+ }
+ }
+ else
+#endif
+ *ptrToBind = targetAddr;
+ return targetAddr;
}
@@ -1830,38 +2091,39 @@
const struct macho_section* const sectionsEnd = §ionsStart[seg->nsects];
for (const struct macho_section* sect=sectionsStart; sect < sectionsEnd; ++sect) {
const uint8_t type = sect->flags & SECTION_TYPE;
+ uint32_t symbolIndex = INDIRECT_SYMBOL_LOCAL;
if ( type == S_LAZY_SYMBOL_POINTERS ) {
const uint32_t pointerCount = sect->size / sizeof(uintptr_t);
uintptr_t* const symbolPointers = (uintptr_t*)(sect->addr + fSlide);
if ( (lazyPointer >= symbolPointers) && (lazyPointer < &symbolPointers[pointerCount]) ) {
const uint32_t indirectTableOffset = sect->reserved1;
const uint32_t lazyIndex = lazyPointer - symbolPointers;
- uint32_t symbolIndex = indirectTable[indirectTableOffset + lazyIndex];
- if ( symbolIndex != INDIRECT_SYMBOL_ABS && symbolIndex != INDIRECT_SYMBOL_LOCAL ) {
- ImageLoader *image = NULL;
- const char *path = NULL;
- uintptr_t symbolAddr = this->resolveUndefined(context, &fSymbolTable[symbolIndex], twoLevel, &image);
- if ( context.verboseBind ) {
- if(NULL == path && NULL != image) {
- path = image->getShortName();
- }
- fprintf(stderr, "dyld: bind: %s:%s$%s = %s:%s, *0x%08lx = 0x%08lx\n",
- this->getShortName(), &fStrings[fSymbolTable[symbolIndex].n_un.n_strx], "lazy_ptr",
- path, &fStrings[fSymbolTable[symbolIndex].n_un.n_strx], (uintptr_t)&symbolPointers[lazyIndex], symbolAddr);
- }
- if ( NULL != context.bindingHandler ) {
- if(NULL == path && NULL != image) {
- path = image->getPath();
- }
- symbolAddr = (uintptr_t)context.bindingHandler(path, &fStrings[fSymbolTable[symbolIndex].n_un.n_strx], (void *)symbolAddr);
- }
- symbolPointers[lazyIndex] = symbolAddr;
- // update stats
- fgTotalLazyBindFixups++;
- return symbolPointers[lazyIndex];
- }
+ symbolIndex = indirectTable[indirectTableOffset + lazyIndex];
}
}
+ #if __i386__
+ else if ( (type == S_SYMBOL_STUBS) && (sect->flags & S_ATTR_SELF_MODIFYING_CODE) && (sect->reserved2 == 5) ) {
+ // 5 bytes stubs on i386 are new "fast stubs"
+ uint8_t* const jmpTableBase = (uint8_t*)(sect->addr + fSlide);
+ uint8_t* const jmpTableEnd = jmpTableBase + sect->size;
+ // initial CALL instruction in jump table leaves pointer to next entry, so back up
+ uint8_t* const jmpTableEntryToPatch = ((uint8_t*)lazyPointer) - 5;
+ lazyPointer = (uintptr_t*)jmpTableEntryToPatch;
+ if ( (jmpTableEntryToPatch >= jmpTableBase) && (jmpTableEntryToPatch < jmpTableEnd) ) {
+ const uint32_t indirectTableOffset = sect->reserved1;
+ const uint32_t entryIndex = (jmpTableEntryToPatch - jmpTableBase)/5;
+ symbolIndex = indirectTable[indirectTableOffset + entryIndex];
+ }
+ }
+ #endif
+ if ( symbolIndex != INDIRECT_SYMBOL_ABS && symbolIndex != INDIRECT_SYMBOL_LOCAL ) {
+ const char* symbolName = &fStrings[fSymbolTable[symbolIndex].n_un.n_strx];
+ ImageLoader* image = NULL;
+ uintptr_t symbolAddr = this->resolveUndefined(context, &fSymbolTable[symbolIndex], twoLevel, &image);
+ symbolAddr = this->bindIndirectSymbol(lazyPointer, sect, symbolName, symbolAddr, image, context);
+ ++fgTotalLazyBindFixups;
+ return symbolAddr;
+ }
}
}
break;
@@ -1870,6 +2132,7 @@
}
throw "lazy pointer not found";
}
+
@@ -1890,26 +2153,37 @@
const struct macho_section* const sectionsEnd = §ionsStart[seg->nsects];
for (const struct macho_section* sect=sectionsStart; sect < sectionsEnd; ++sect) {
const uint8_t type = sect->flags & SECTION_TYPE;
- const uint32_t pointerCount = sect->size / sizeof(uintptr_t);
+ uint32_t elementSize = sizeof(uintptr_t);
+ uint32_t elementCount = sect->size / elementSize;
if ( type == S_NON_LAZY_SYMBOL_POINTERS ) {
if ( (bindness == kLazyOnly) || (bindness == kLazyOnlyNoDependents) )
continue;
}
else if ( type == S_LAZY_SYMBOL_POINTERS ) {
// process each symbol pointer in this section
- fgTotalPossibleLazyBindFixups += pointerCount;
+ fgTotalPossibleLazyBindFixups += elementCount;
if ( bindness == kNonLazyOnly )
continue;
}
+ #if __i386__
+ else if ( (type == S_SYMBOL_STUBS) && (sect->flags & S_ATTR_SELF_MODIFYING_CODE) && (sect->reserved2 == 5) ) {
+ // process each jmp entry in this section
+ elementCount = sect->size / 5;
+ elementSize = 5;
+ fgTotalPossibleLazyBindFixups += elementCount;
+ if ( bindness == kNonLazyOnly )
+ continue;
+ }
+ #endif
else {
continue;
}
const uint32_t indirectTableOffset = sect->reserved1;
- uintptr_t* const symbolPointers = (uintptr_t*)(sect->addr + fSlide);
- for (uint32_t j=0; j < pointerCount; ++j) {
+ uint8_t* ptrToBind = (uint8_t*)(sect->addr + fSlide);
+ for (uint32_t j=0; j < elementCount; ++j, ptrToBind += elementSize) {
uint32_t symbolIndex = indirectTable[indirectTableOffset + j];
if ( symbolIndex == INDIRECT_SYMBOL_LOCAL) {
- symbolPointers[j] += this->fSlide;
+ *((uintptr_t*)ptrToBind) += this->fSlide;
}
else if ( symbolIndex == INDIRECT_SYMBOL_ABS) {
// do nothing since already has absolute address
@@ -1947,27 +2221,13 @@
continue;
uintptr_t symbolAddr;
symbolAddr = resolveUndefined(context, sym, twoLevel, &image);
- if ( context.verboseBind ) {
- const char *path = NULL;
- if(NULL != image) {
- path = image->getShortName();
- }
- const char *typeName;
- if ( type == S_LAZY_SYMBOL_POINTERS ) {
- typeName = "lazy_ptr";
- }
- else {
- typeName = "non_lazy_ptr";
- }
- fprintf(stderr, "dyld: bind: %s:%s$%s = %s:%s, *0x%08lx = 0x%08lx\n",
- this->getShortName(), &fStrings[sym->n_un.n_strx], typeName,
- path, &fStrings[sym->n_un.n_strx], (uintptr_t)&symbolPointers[j], symbolAddr);
- }
- symbolPointers[j] = symbolAddr;
+
+ // update pointer
+ symbolAddr = this->bindIndirectSymbol((uintptr_t*)ptrToBind, sect, &fStrings[sym->n_un.n_strx], symbolAddr, image, context);
}
}
// update stats
- fgTotalBindFixups += pointerCount;
+ fgTotalBindFixups += elementCount;
}
}
break;
@@ -2006,9 +2266,10 @@
// These are defined in dyldStartup.s
extern "C" void stub_binding_helper();
extern "C" bool dyld_func_lookup(const char* name, uintptr_t* address);
-
-
-void ImageLoaderMachO::setupLazyPointerHandler()
+extern "C" void fast_stub_binding_helper_interface();
+
+
+void ImageLoaderMachO::setupLazyPointerHandler(const LinkContext& context)
{
if ( fDATAdyld != NULL ) {
struct DATAdyld* dd = (struct DATAdyld*)(fDATAdyld->addr + fSlide);
@@ -2027,12 +2288,51 @@
// save = dd->stubBindHelper;
#endif
}
+#if __i386__
+ if ( ! this->usablePrebinding(context) || !this->usesTwoLevelNameSpace() ) {
+ // reset all "fast" stubs
+ const uint32_t cmd_count = ((macho_header*)fMachOData)->ncmds;
+ const struct load_command* const cmds = (struct load_command*)&fMachOData[sizeof(macho_header)];
+ const struct load_command* cmd = cmds;
+ for (uint32_t i = 0; i < cmd_count; ++i) {
+ switch (cmd->cmd) {
+ case LC_SEGMENT_COMMAND:
+ {
+ const struct macho_segment_command* seg = (struct macho_segment_command*)cmd;
+ const struct macho_section* const sectionsStart = (struct macho_section*)((char*)seg + sizeof(struct macho_segment_command));
+ const struct macho_section* const sectionsEnd = §ionsStart[seg->nsects];
+ for (const struct macho_section* sect=sectionsStart; sect < sectionsEnd; ++sect) {
+ 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
+ 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;
+ }
+ }
+ }
+ }
+ }
+ cmd = (const struct load_command*)(((char*)cmd)+cmd->cmdsize);
+ }
+ }
+#endif
}
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()
+ && this->allDependentLibrariesAsWhenPreBound() ) {
// allow environment variables to disable prebinding
if ( context.bindFlat )
return false;
@@ -2053,13 +2353,13 @@
void ImageLoaderMachO::doBind(const LinkContext& context, BindingLaziness bindness)
{
// set dyld entry points in image
- this->setupLazyPointerHandler();
+ this->setupLazyPointerHandler(context);
// if prebound and loaded at prebound address, and all libraries are same as when this was prebound, then no need to bind
// note: flat-namespace binaries need to be imports rebound (even if correctly prebound)
if ( this->usablePrebinding(context) && this->usesTwoLevelNameSpace() ) {
- // if image has coalesced symbols, then these need to be rebound
- if ( this->needsCoalescing() ) {
+ // if image has coalesced symbols, then these need to be rebound, unless this is the only image with weak symbols
+ if ( this->needsCoalescing() && (fgCountOfImagesWithWeakExports > 1) ) {
this->doBindExternalRelocations(context, true);
this->doBindIndirectSymbolPointers(context, kLazyAndNonLazy, true);
}
@@ -2164,6 +2464,7 @@
ImageLoader::printStatistics(imageCount);
fprintf(stderr, "total hinted binary tree searches: %d\n", fgHintedBinaryTreeSearchs);
fprintf(stderr, "total unhinted binary tree searches: %d\n", fgUnhintedBinaryTreeSearchs);
+ fprintf(stderr, "total images with weak exports: %d\n", fgCountOfImagesWithWeakExports);
#if LINKEDIT_USAGE_DEBUG
fprintf(stderr, "linkedit pages accessed (%lu):\n", sLinkEditPageBuckets.size());
@@ -2296,13 +2597,14 @@
// walk all exports and slide their n_value
struct macho_nlist* lastExport = &symbolTable[dysymtab->iextdefsym+dysymtab->nextdefsym];
for (struct macho_nlist* entry = &symbolTable[dysymtab->iextdefsym]; entry < lastExport; ++entry) {
- entry->n_value += fSlide;
+ if ( (entry->n_type & N_TYPE) == N_SECT )
+ entry->n_value += fSlide;
}
// walk all local symbols and slide their n_value
struct macho_nlist* lastLocal = &symbolTable[dysymtab->ilocalsym+dysymtab->nlocalsym];
for (struct macho_nlist* entry = &symbolTable[dysymtab->ilocalsym]; entry < lastLocal; ++entry) {
- if ( (entry->n_type & N_TYPE) == N_SECT )
+ if ( entry->n_sect != NO_SECT )
entry->n_value += fSlide;
}
@@ -2316,7 +2618,7 @@
switch(sreloc->r_type) {
#if __ppc__ || __ppc64__
case PPC_RELOC_PB_LA_PTR:
- #elif __i386__
+ #elif __i386__ || __x86_64__
case GENERIC_RELOC_PB_LA_PTR:
#else
#error unknown architecture
@@ -2327,8 +2629,67 @@
}
}
}
-
-}
+
+ // if multi-module, fix up objc_addr (10.4 and later runtime does not use this, but we want to keep file checksum consistent)
+ if ( dysymtab->nmodtab != 0 ) {
+ dylib_module* const modulesStart = (struct dylib_module*)(&fileToPrebind[dysymtab->modtaboff]);
+ dylib_module* const modulesEnd = &modulesStart[dysymtab->nmodtab];
+ for (dylib_module* module=modulesStart; module < modulesEnd; ++module) {
+ if ( module->objc_module_info_size != 0 ) {
+ module->objc_module_info_addr += fSlide;
+ }
+ }
+ }
+}
+
+// file on disk has been reprebound, but we are still mapped to old file
+void ImageLoaderMachO::prebindUnmap(const LinkContext& context)
+{
+ // this removes all mappings to the old file, so the kernel will unlink (delete) it.
+ // We need to leave the load commands and __LINKEDIT in place
+ for (std::vector<class Segment*>::iterator it=fSegments.begin(); it != fSegments.end(); ++it) {
+ void* segmentAddress = (void*)((*it)->getActualLoadAddress());
+ uintptr_t segmentSize = (*it)->getSize();
+ //fprintf(stderr, "unmapping segment %s at %p for %s\n", (*it)->getName(), segmentAddress, this->getPath());
+ // save load commands at beginning of __TEXT segment
+ if ( segmentAddress == fMachOData ) {
+ // typically load commands are one or two pages in size, so ok to alloc on stack
+ uint32_t loadCmdSize = sizeof(macho_header) + ((macho_header*)fMachOData)->sizeofcmds;
+ uint32_t loadCmdPages = (loadCmdSize+4095) & (-4096);
+ uint8_t loadcommands[loadCmdPages];
+ memcpy(loadcommands, fMachOData, loadCmdPages);
+ // unmap whole __TEXT segment
+ munmap((void*)(fMachOData), segmentSize);
+ // allocate and copy back mach_header and load commands
+ vm_address_t addr = (vm_address_t)fMachOData;
+ int r2 = vm_allocate(mach_task_self(), &addr, loadCmdPages, false /*at this address*/);
+ if ( r2 != 0 )
+ fprintf(stderr, "prebindUnmap() vm_allocate for __TEXT %d failed\n", loadCmdPages);
+ memcpy((void*)fMachOData, loadcommands, loadCmdPages);
+ //fprintf(stderr, "copying back load commands to %p size=%u for %s\n", segmentAddress, loadCmdPages, this->getPath());
+ }
+ else if ( strcmp((*it)->getName(), "__LINKEDIT") == 0 ) {
+ uint32_t linkEditSize = segmentSize;
+ uint32_t linkEditPages = (linkEditSize+4095) & (-4096);
+ void* linkEditTmp = malloc(linkEditPages);
+ memcpy(linkEditTmp, segmentAddress, linkEditPages);
+ // unmap whole __LINKEDIT segment
+ munmap(segmentAddress, segmentSize);
+ vm_address_t addr = (vm_address_t)segmentAddress;
+ int r2 = vm_allocate(mach_task_self(), &addr, linkEditPages, false /*at this address*/);
+ if ( r2 != 0 )
+ fprintf(stderr, "prebindUnmap() vm_allocate for __LINKEDIT %d failed\n", linkEditPages);
+ memcpy(segmentAddress, linkEditTmp, linkEditPages);
+ //fprintf(stderr, "copying back __LINKEDIT to %p size=%u for %s\n", segmentAddress, linkEditPages, this->getPath());
+ free(linkEditTmp);
+ }
+ else {
+ // unmap any other segment
+ munmap((void*)(segmentAddress), (*it)->getSize());
+ }
+ }
+}
+
SegmentMachO::SegmentMachO(const struct macho_segment_command* cmd, ImageLoaderMachO* image, const uint8_t* fileData)