Patchwork [00/13] Request to merge Address Sanitizer in

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Submitter Jack Howarth
Date Nov. 16, 2012, 3:57 p.m.
Message ID <20121116155704.GA26787@bromo.med.uc.edu>
Download mbox | patch
Permalink /patch/199675/
State New
Headers show

Comments

Jack Howarth - Nov. 16, 2012, 3:57 p.m.
On Fri, Nov 16, 2012 at 09:27:26AM +0100, Dodji Seketeli wrote:
> Jack Howarth <howarth@bromo.med.uc.edu> writes:
> 
> >     The Google branch is missing the required
> > interception/mach_override/mach_override.h and
> > interception/mach_override/mach_override.c files from compiler-rt svn
> > for darwin. I have posted what I believe to be the final patch which
> > eanbles libsanitizer on darwin...
> >
> > http://gcc.gnu.org/ml/gcc-patches/2012-11/msg01285.html
> 
> I see in that thread that Mike Stump has approves the patch if no
> asan{-darwin} people disagrees.  I'll abide by principle, FWIW.  :-)
> 
> > which has been tested with the existing asan testsuite, the
> > use-after-free.c testcase as well as the Polyhedron 2005 benchmarks
> > for -O1 -g -fno-omit-frame-pointer -faddress-sanitizer and -O3
> > -funroll-loops -ffast-math -g -fno-omit-frame-pointer
> > -faddress-sanitizer to prove that the current mach_override from
> > upstream is sufficient for darwin to use.
> 
> I see.   Thanks.
> 
> > Due to the large number of maintainers for libsanitizer, it is unclear
> > who is the person responsible for upstream merges to lobby for these
> > files to be ported into gcc trunk.  With Alexander Potapenko's commit
> > of the bug fix to mach_override/mach_override.c required for FSF
> > gcc...
> >
> > http://lists.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20121112/155989.html
> >
> > ...there really is no reason to continue to delay (as the interpose code simply won't
> > be completed in time for gcc 4.8.0).
> 
> It makes sense to me.
> 
> > Can we please get some movement on importing these missing files from
> > upstream?
> 
> Well, given that ....
> 
> Konstantin Serebryany <konstantin.s.serebryany@gmail.com> writes:
> 
> > I see no problems with committing mach_override to gcc.
> > The code should be verbatim copy from
> > llvm/projects/compiler-rt/lib/interception/mach_override
> > Note that this code comes with an MIT license and was not developed by
> > Google (we did add quite a few patches).
> 
> ... Konstantin who is one of the libsanitizer maintainers agrees, I see
> no reason to delay this either.
> 
> So, Jack, as you are on top of this topic and has the platform to test
> at hand, I guess you could just import the missing files from the llvm
> repository and commit them to GCC, unless a GCC maintainers disagrees,
> of course.

Dodji,
    Attached is a new version of the patch adjusted for the bit-rot from
the maintainer-mode checkins of today and with the missing files for
libsanitizer/interception/mach_override/mach_override.c and 
libsanitizer/interception/mach_override/mach_override.h from llvm
compiler-rt svn at...

------------------------------------------------------------------------
r168032 | glider | 2012-11-15 03:32:16 -0500 (Thu, 15 Nov 2012) | 3 lines

[ASan] Add the "lea $imm(%rip),%rax" instruction to mach_override.c
The need for this has been reported by Jack Howarth (howarth@bromo.med.uc.edu) who's porting ASan-Darwin to GCC

added to the patch so that you can make any required licensing adjustments to
the comments at the top of those files. Hopefully we can get this in soon as
the build parts keep bit-rotting.
        Jack
ps I added you to the ChangeLog for the llvm file imports since I believe that should be
done by the libsanitizer maintainers. Thanks in advance for handling the commit in
both gcc trunk and gcc asan branch.

> 
> Thus, you could maybe just send the patch of the file you are about to
> commit as a reply to this thread, so that Konstantin and Alexander can
> officially ACK it?  I am mentioning Alexander because of what Konstantin
> is saying ...
> 
> > Also, Alexander Potapenko is the best person to ask about asan-darwin.
> 
> .... here.
> 
> > Maybe we can add him to the list of sanitizer maintainers?
> 
> Seconded.  At least for libsanitier/Darwin.
> 
> Cheers.
> 
> -- 
> 		Dodji
gcc/

2012-11-16  Jack Howarth <howarth@bromo.med.uc.edu>

	* config/darwin.h (LINK_COMMAND_SPEC_A): Deal with -faddress-sanitizer.

libsanitizer/

2012-11-16  Dodji Seketeli <dodji@redhat.com>
	    Jack Howarth <howarth@bromo.med.uc.edu>

	* interception/mach_override/mach_override.c: Migrate from llvm.
	* interception/mach_override/mach_override.h: Likewise.
	* configure.tgt: Add darwin to supported targets.
	* configure.ac: Define USING_MACH_OVERRIDE when on darwin.
	* interception/Makefile.am: Compile mach_override.c when
	USING_MACH_OVERRIDE defined.
	* configure: Regenerated.
	* interception/Makefile.in: Likewise.
Jakub Jelinek - Nov. 16, 2012, 4 p.m.
On Fri, Nov 16, 2012 at 10:57:04AM -0500, Jack Howarth wrote:
> +case "$host" in
> +  *-*-darwin*) MACH_OVERRIDE=true ;;
> +  *) MACH_OVERRIDE=false ;;
> +esac
> +AM_CONDITIONAL(USING_MACH_OVERRIDE, $MACH_OVERRIDE)
> +

Shouldn't AM_CONDITIONAL follow AM_INIT_AUTOMAKE?  I'd say move it
before AC_CONFIG_FILES or so.

	Jakub

Patch

--- /dev/null	2012-11-16 10:24:58.000000000 -0500
+++ libsanitizer/interception/mach_override/mach_override.c	2012-11-16 10:26:42.000000000 -0500
@@ -0,0 +1,970 @@ 
+/*******************************************************************************
+	mach_override.c
+		Copyright (c) 2003-2009 Jonathan 'Wolf' Rentzsch: <http://rentzsch.com>
+		Some rights reserved: <http://opensource.org/licenses/mit-license.php>
+
+	***************************************************************************/
+#ifdef __APPLE__
+
+#include "mach_override.h"
+
+#include <mach-o/dyld.h>
+#include <mach/mach_host.h>
+#include <mach/mach_init.h>
+#include <mach/vm_map.h>
+#include <sys/mman.h>
+
+#include <CoreServices/CoreServices.h>
+
+//#define DEBUG_DISASM 1
+#undef DEBUG_DISASM
+
+/**************************
+*	
+*	Constants
+*	
+**************************/
+#pragma mark	-
+#pragma mark	(Constants)
+
+#if defined(__ppc__) || defined(__POWERPC__)
+
+static
+long kIslandTemplate[] = {
+	0x9001FFFC,	//	stw		r0,-4(SP)
+	0x3C00DEAD,	//	lis		r0,0xDEAD
+	0x6000BEEF,	//	ori		r0,r0,0xBEEF
+	0x7C0903A6,	//	mtctr	r0
+	0x8001FFFC,	//	lwz		r0,-4(SP)
+	0x60000000,	//	nop		; optionally replaced
+	0x4E800420 	//	bctr
+};
+
+#define kAddressHi			3
+#define kAddressLo			5
+#define kInstructionHi		10
+#define kInstructionLo		11
+
+#elif defined(__i386__) 
+
+#define kOriginalInstructionsSize 16
+
+static
+unsigned char kIslandTemplate[] = {
+	// kOriginalInstructionsSize nop instructions so that we 
+	// should have enough space to host original instructions 
+	0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 
+	0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90,
+	// Now the real jump instruction
+	0xE9, 0xEF, 0xBE, 0xAD, 0xDE
+};
+
+#define kInstructions	0
+#define kJumpAddress    kInstructions + kOriginalInstructionsSize + 1
+#elif defined(__x86_64__)
+
+#define kOriginalInstructionsSize 32
+
+#define kJumpAddress    kOriginalInstructionsSize + 6
+
+static
+unsigned char kIslandTemplate[] = {
+	// kOriginalInstructionsSize nop instructions so that we 
+	// should have enough space to host original instructions 
+	0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 
+	0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90,
+	0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 
+	0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90,
+	// Now the real jump instruction
+	0xFF, 0x25, 0x00, 0x00, 0x00, 0x00,
+        0x00, 0x00, 0x00, 0x00,
+        0x00, 0x00, 0x00, 0x00
+};
+
+#endif
+
+#define	kAllocateHigh		1
+#define	kAllocateNormal		0
+
+/**************************
+*	
+*	Data Types
+*	
+**************************/
+#pragma mark	-
+#pragma mark	(Data Types)
+
+typedef	struct	{
+	char	instructions[sizeof(kIslandTemplate)];
+	int		allocatedHigh;
+}	BranchIsland;
+
+/**************************
+*	
+*	Funky Protos
+*	
+**************************/
+#pragma mark	-
+#pragma mark	(Funky Protos)
+
+
+	static mach_error_t
+allocateBranchIsland(
+		BranchIsland	**island,
+		int				allocateHigh,
+		void *originalFunctionAddress);
+
+	static mach_error_t
+freeBranchIsland(
+		BranchIsland	*island );
+
+	static mach_error_t
+defaultIslandMalloc(
+	  void **ptr, size_t unused_size, void *hint);
+
+	static mach_error_t
+defaultIslandFree(
+   	void *ptr);
+
+#if defined(__ppc__) || defined(__POWERPC__)
+	static mach_error_t
+setBranchIslandTarget(
+		BranchIsland	*island,
+		const void		*branchTo,
+		long			instruction );
+#endif 
+
+#if defined(__i386__) || defined(__x86_64__)
+static mach_error_t
+setBranchIslandTarget_i386(
+						   BranchIsland	*island,
+						   const void		*branchTo,
+						   char*			instructions );
+// Can't be made static because there's no C implementation for atomic_mov64
+// on i386.
+void 
+atomic_mov64(
+		uint64_t *targetAddress,
+		uint64_t value ) __attribute__((visibility("hidden")));
+
+	static Boolean 
+eatKnownInstructions( 
+	unsigned char	*code, 
+	uint64_t		*newInstruction,
+	int				*howManyEaten, 
+	char			*originalInstructions,
+	int				*originalInstructionCount, 
+	uint8_t			*originalInstructionSizes );
+
+	static void
+fixupInstructions(
+    void		*originalFunction,
+    void		*escapeIsland,
+    void		*instructionsToFix,
+	int			instructionCount,
+	uint8_t		*instructionSizes );
+
+#ifdef DEBUG_DISASM
+	static void
+dump16Bytes(
+	void	*ptr);
+#endif  // DEBUG_DISASM
+#endif
+
+/*******************************************************************************
+*	
+*	Interface
+*	
+*******************************************************************************/
+#pragma mark	-
+#pragma mark	(Interface)
+
+#if defined(__i386__) || defined(__x86_64__)
+static mach_error_t makeIslandExecutable(void *address) {
+	mach_error_t err = err_none;
+    vm_size_t pageSize;
+    host_page_size( mach_host_self(), &pageSize );
+    uintptr_t page = (uintptr_t)address & ~(uintptr_t)(pageSize-1);
+    int e = err_none;
+    e |= mprotect((void *)page, pageSize, PROT_EXEC | PROT_READ | PROT_WRITE);
+    e |= msync((void *)page, pageSize, MS_INVALIDATE );
+    if (e) {
+        err = err_cannot_override;
+    }
+    return err;
+}
+#endif
+
+		static mach_error_t
+defaultIslandMalloc(
+	void **ptr, size_t unused_size, void *hint) {
+  return allocateBranchIsland( (BranchIsland**)ptr, kAllocateHigh, hint );
+}
+		static mach_error_t
+defaultIslandFree(
+	void *ptr) {
+	return freeBranchIsland(ptr);
+}
+
+    mach_error_t
+__asan_mach_override_ptr(
+	void *originalFunctionAddress,
+    const void *overrideFunctionAddress,
+    void **originalFunctionReentryIsland )
+{
+  return __asan_mach_override_ptr_custom(originalFunctionAddress,
+		overrideFunctionAddress,
+		originalFunctionReentryIsland,
+		defaultIslandMalloc,
+		defaultIslandFree);
+}
+
+    mach_error_t
+__asan_mach_override_ptr_custom(
+	void *originalFunctionAddress,
+    const void *overrideFunctionAddress,
+    void **originalFunctionReentryIsland,
+		island_malloc *alloc,
+		island_free *dealloc)
+{
+	assert( originalFunctionAddress );
+	assert( overrideFunctionAddress );
+	
+	// this addresses overriding such functions as AudioOutputUnitStart()
+	// test with modified DefaultOutputUnit project
+#if defined(__x86_64__)
+    for(;;){
+        if(*(uint16_t*)originalFunctionAddress==0x25FF)    // jmp qword near [rip+0x????????]
+            originalFunctionAddress=*(void**)((char*)originalFunctionAddress+6+*(int32_t *)((uint16_t*)originalFunctionAddress+1));
+        else break;
+    }
+#elif defined(__i386__)
+    for(;;){
+        if(*(uint16_t*)originalFunctionAddress==0x25FF)    // jmp *0x????????
+            originalFunctionAddress=**(void***)((uint16_t*)originalFunctionAddress+1);
+        else break;
+    }
+#endif
+#ifdef DEBUG_DISASM
+  {
+    fprintf(stderr, "Replacing function at %p\n", originalFunctionAddress);
+    fprintf(stderr, "First 16 bytes of the function: ");
+    unsigned char *orig = (unsigned char *)originalFunctionAddress;
+    int i;
+    for (i = 0; i < 16; i++) {
+       fprintf(stderr, "%x ", (unsigned int) orig[i]);
+    }
+    fprintf(stderr, "\n");
+    fprintf(stderr, 
+            "To disassemble, save the following function as disas.c"
+            " and run:\n  gcc -c disas.c && gobjdump -d disas.o\n"
+            "The first 16 bytes of the original function will start"
+            " after four nop instructions.\n");
+    fprintf(stderr, "\nvoid foo() {\n  asm volatile(\"nop;nop;nop;nop;\");\n");
+    int j = 0;
+    for (j = 0; j < 2; j++) {
+      fprintf(stderr, "  asm volatile(\".byte ");
+      for (i = 8 * j; i < 8 * (j+1) - 1; i++) {
+        fprintf(stderr, "0x%x, ", (unsigned int) orig[i]);
+      }
+      fprintf(stderr, "0x%x;\");\n", (unsigned int) orig[8 * (j+1) - 1]);
+    }
+    fprintf(stderr, "}\n\n");
+  }
+#endif
+
+	long	*originalFunctionPtr = (long*) originalFunctionAddress;
+	mach_error_t	err = err_none;
+	
+#if defined(__ppc__) || defined(__POWERPC__)
+	//	Ensure first instruction isn't 'mfctr'.
+	#define	kMFCTRMask			0xfc1fffff
+	#define	kMFCTRInstruction	0x7c0903a6
+	
+	long	originalInstruction = *originalFunctionPtr;
+	if( !err && ((originalInstruction & kMFCTRMask) == kMFCTRInstruction) )
+		err = err_cannot_override;
+#elif defined(__i386__) || defined(__x86_64__)
+	int eatenCount = 0;
+	int originalInstructionCount = 0;
+	char originalInstructions[kOriginalInstructionsSize];
+	uint8_t originalInstructionSizes[kOriginalInstructionsSize];
+	uint64_t jumpRelativeInstruction = 0; // JMP
+
+	Boolean overridePossible = eatKnownInstructions ((unsigned char *)originalFunctionPtr, 
+										&jumpRelativeInstruction, &eatenCount, 
+										originalInstructions, &originalInstructionCount, 
+										originalInstructionSizes );
+#ifdef DEBUG_DISASM
+  if (!overridePossible) fprintf(stderr, "overridePossible = false @%d\n", __LINE__);
+#endif
+	if (eatenCount > kOriginalInstructionsSize) {
+#ifdef DEBUG_DISASM
+		fprintf(stderr, "Too many instructions eaten\n");
+#endif    
+		overridePossible = false;
+	}
+	if (!overridePossible) err = err_cannot_override;
+	if (err) fprintf(stderr, "err = %x %s:%d\n", err, __FILE__, __LINE__);
+#endif
+	
+	//	Make the original function implementation writable.
+	if( !err ) {
+		err = vm_protect( mach_task_self(),
+				(vm_address_t) originalFunctionPtr, 8, false,
+				(VM_PROT_ALL | VM_PROT_COPY) );
+		if( err )
+			err = vm_protect( mach_task_self(),
+					(vm_address_t) originalFunctionPtr, 8, false,
+					(VM_PROT_DEFAULT | VM_PROT_COPY) );
+	}
+	if (err) fprintf(stderr, "err = %x %s:%d\n", err, __FILE__, __LINE__);
+	
+	//	Allocate and target the escape island to the overriding function.
+	BranchIsland	*escapeIsland = NULL;
+	if( !err )
+		err = alloc( (void**)&escapeIsland, sizeof(BranchIsland), originalFunctionAddress );
+	if ( err ) fprintf(stderr, "err = %x %s:%d\n", err, __FILE__, __LINE__);
+	
+#if defined(__ppc__) || defined(__POWERPC__)
+	if( !err )
+		err = setBranchIslandTarget( escapeIsland, overrideFunctionAddress, 0 );
+	
+	//	Build the branch absolute instruction to the escape island.
+	long	branchAbsoluteInstruction = 0; // Set to 0 just to silence warning.
+	if( !err ) {
+		long escapeIslandAddress = ((long) escapeIsland) & 0x3FFFFFF;
+		branchAbsoluteInstruction = 0x48000002 | escapeIslandAddress;
+	}
+#elif defined(__i386__) || defined(__x86_64__)
+        if (err) fprintf(stderr, "err = %x %s:%d\n", err, __FILE__, __LINE__);
+
+	if( !err )
+		err = setBranchIslandTarget_i386( escapeIsland, overrideFunctionAddress, 0 );
+ 
+	if (err) fprintf(stderr, "err = %x %s:%d\n", err, __FILE__, __LINE__);
+	// Build the jump relative instruction to the escape island
+#endif
+
+
+#if defined(__i386__) || defined(__x86_64__)
+	if (!err) {
+		uint32_t addressOffset = ((char*)escapeIsland - (char*)originalFunctionPtr - 5);
+		addressOffset = OSSwapInt32(addressOffset);
+		
+		jumpRelativeInstruction |= 0xE900000000000000LL; 
+		jumpRelativeInstruction |= ((uint64_t)addressOffset & 0xffffffff) << 24;
+		jumpRelativeInstruction = OSSwapInt64(jumpRelativeInstruction);		
+	}
+#endif
+	
+	//	Optionally allocate & return the reentry island. This may contain relocated
+	//  jmp instructions and so has all the same addressing reachability requirements
+	//  the escape island has to the original function, except the escape island is
+	//  technically our original function.
+	BranchIsland	*reentryIsland = NULL;
+	if( !err && originalFunctionReentryIsland ) {
+		err = alloc( (void**)&reentryIsland, sizeof(BranchIsland), escapeIsland);
+		if( !err )
+			*originalFunctionReentryIsland = reentryIsland;
+	}
+	
+#if defined(__ppc__) || defined(__POWERPC__)	
+	//	Atomically:
+	//	o If the reentry island was allocated:
+	//		o Insert the original instruction into the reentry island.
+	//		o Target the reentry island at the 2nd instruction of the
+	//		  original function.
+	//	o Replace the original instruction with the branch absolute.
+	if( !err ) {
+		int escapeIslandEngaged = false;
+		do {
+			if( reentryIsland )
+				err = setBranchIslandTarget( reentryIsland,
+						(void*) (originalFunctionPtr+1), originalInstruction );
+			if( !err ) {
+				escapeIslandEngaged = CompareAndSwap( originalInstruction,
+										branchAbsoluteInstruction,
+										(UInt32*)originalFunctionPtr );
+				if( !escapeIslandEngaged ) {
+					//	Someone replaced the instruction out from under us,
+					//	re-read the instruction, make sure it's still not
+					//	'mfctr' and try again.
+					originalInstruction = *originalFunctionPtr;
+					if( (originalInstruction & kMFCTRMask) == kMFCTRInstruction)
+						err = err_cannot_override;
+				}
+			}
+		} while( !err && !escapeIslandEngaged );
+	}
+#elif defined(__i386__) || defined(__x86_64__)
+	// Atomically:
+	//	o If the reentry island was allocated:
+	//		o Insert the original instructions into the reentry island.
+	//		o Target the reentry island at the first non-replaced 
+	//        instruction of the original function.
+	//	o Replace the original first instructions with the jump relative.
+	//
+	// Note that on i386, we do not support someone else changing the code under our feet
+	if ( !err ) {
+		fixupInstructions(originalFunctionPtr, reentryIsland, originalInstructions,
+					originalInstructionCount, originalInstructionSizes );
+	
+		if( reentryIsland )
+			err = setBranchIslandTarget_i386( reentryIsland,
+										 (void*) ((char *)originalFunctionPtr+eatenCount), originalInstructions );
+		// try making islands executable before planting the jmp
+#if defined(__x86_64__) || defined(__i386__)
+        if( !err )
+            err = makeIslandExecutable(escapeIsland);
+        if( !err && reentryIsland )
+            err = makeIslandExecutable(reentryIsland);
+#endif
+		if ( !err )
+			atomic_mov64((uint64_t *)originalFunctionPtr, jumpRelativeInstruction);
+	}
+#endif
+	
+	//	Clean up on error.
+	if( err ) {
+		if( reentryIsland )
+			dealloc( reentryIsland );
+		if( escapeIsland )
+			dealloc( escapeIsland );
+	}
+
+#ifdef DEBUG_DISASM
+  {
+    fprintf(stderr, "First 16 bytes of the function after slicing: ");
+    unsigned char *orig = (unsigned char *)originalFunctionAddress;
+    int i;
+    for (i = 0; i < 16; i++) {
+       fprintf(stderr, "%x ", (unsigned int) orig[i]);
+    }
+    fprintf(stderr, "\n");
+  }
+#endif
+	return err;
+}
+
+/*******************************************************************************
+*	
+*	Implementation
+*	
+*******************************************************************************/
+#pragma mark	-
+#pragma mark	(Implementation)
+
+/***************************************************************************//**
+	Implementation: Allocates memory for a branch island.
+	
+	@param	island			<-	The allocated island.
+	@param	allocateHigh	->	Whether to allocate the island at the end of the
+								address space (for use with the branch absolute
+								instruction).
+	@result					<-	mach_error_t
+
+	***************************************************************************/
+
+	static mach_error_t
+allocateBranchIsland(
+		BranchIsland	**island,
+		int				allocateHigh,
+		void *originalFunctionAddress)
+{
+	assert( island );
+	
+	mach_error_t	err = err_none;
+	
+	if( allocateHigh ) {
+		vm_size_t pageSize;
+		err = host_page_size( mach_host_self(), &pageSize );
+		if( !err ) {
+			assert( sizeof( BranchIsland ) <= pageSize );
+#if defined(__ppc__) || defined(__POWERPC__)
+			vm_address_t first = 0xfeffffff;
+			vm_address_t last = 0xfe000000 + pageSize;
+#elif defined(__x86_64__)
+			vm_address_t first = ((uint64_t)originalFunctionAddress & ~(uint64_t)(((uint64_t)1 << 31) - 1)) | ((uint64_t)1 << 31); // start in the middle of the page?
+			vm_address_t last = 0x0;
+#else
+			vm_address_t first = 0xffc00000;
+			vm_address_t last = 0xfffe0000;
+#endif
+
+			vm_address_t page = first;
+			int allocated = 0;
+			vm_map_t task_self = mach_task_self();
+			
+			while( !err && !allocated && page != last ) {
+
+				err = vm_allocate( task_self, &page, pageSize, 0 );
+				if( err == err_none )
+					allocated = 1;
+				else if( err == KERN_NO_SPACE ) {
+#if defined(__x86_64__)
+					page -= pageSize;
+#else
+					page += pageSize;
+#endif
+					err = err_none;
+				}
+			}
+			if( allocated )
+				*island = (BranchIsland*) page;
+			else if( !allocated && !err )
+				err = KERN_NO_SPACE;
+		}
+	} else {
+		void *block = malloc( sizeof( BranchIsland ) );
+		if( block )
+			*island = block;
+		else
+			err = KERN_NO_SPACE;
+	}
+	if( !err )
+		(**island).allocatedHigh = allocateHigh;
+	
+	return err;
+}
+
+/***************************************************************************//**
+	Implementation: Deallocates memory for a branch island.
+	
+	@param	island	->	The island to deallocate.
+	@result			<-	mach_error_t
+
+	***************************************************************************/
+
+	static mach_error_t
+freeBranchIsland(
+		BranchIsland	*island )
+{
+	assert( island );
+	assert( (*(long*)&island->instructions[0]) == kIslandTemplate[0] );
+	assert( island->allocatedHigh );
+	
+	mach_error_t	err = err_none;
+	
+	if( island->allocatedHigh ) {
+		vm_size_t pageSize;
+		err = host_page_size( mach_host_self(), &pageSize );
+		if( !err ) {
+			assert( sizeof( BranchIsland ) <= pageSize );
+			err = vm_deallocate(
+					mach_task_self(),
+					(vm_address_t) island, pageSize );
+		}
+	} else {
+		free( island );
+	}
+	
+	return err;
+}
+
+/***************************************************************************//**
+	Implementation: Sets the branch island's target, with an optional
+	instruction.
+	
+	@param	island		->	The branch island to insert target into.
+	@param	branchTo	->	The address of the target.
+	@param	instruction	->	Optional instruction to execute prior to branch. Set
+							to zero for nop.
+	@result				<-	mach_error_t
+
+	***************************************************************************/
+#if defined(__ppc__) || defined(__POWERPC__)
+	static mach_error_t
+setBranchIslandTarget(
+		BranchIsland	*island,
+		const void		*branchTo,
+		long			instruction )
+{
+	//	Copy over the template code.
+    bcopy( kIslandTemplate, island->instructions, sizeof( kIslandTemplate ) );
+    
+    //	Fill in the address.
+    ((short*)island->instructions)[kAddressLo] = ((long) branchTo) & 0x0000FFFF;
+    ((short*)island->instructions)[kAddressHi]
+    	= (((long) branchTo) >> 16) & 0x0000FFFF;
+    
+    //	Fill in the (optional) instuction.
+    if( instruction != 0 ) {
+        ((short*)island->instructions)[kInstructionLo]
+        	= instruction & 0x0000FFFF;
+        ((short*)island->instructions)[kInstructionHi]
+        	= (instruction >> 16) & 0x0000FFFF;
+    }
+    
+    //MakeDataExecutable( island->instructions, sizeof( kIslandTemplate ) );
+	msync( island->instructions, sizeof( kIslandTemplate ), MS_INVALIDATE );
+    
+    return err_none;
+}
+#endif 
+
+#if defined(__i386__)
+	static mach_error_t
+setBranchIslandTarget_i386(
+	BranchIsland	*island,
+	const void		*branchTo,
+	char*			instructions )
+{
+
+	//	Copy over the template code.
+    bcopy( kIslandTemplate, island->instructions, sizeof( kIslandTemplate ) );
+
+	// copy original instructions
+	if (instructions) {
+		bcopy (instructions, island->instructions + kInstructions, kOriginalInstructionsSize);
+	}
+	
+    // Fill in the address.
+    int32_t addressOffset = (char *)branchTo - (island->instructions + kJumpAddress + 4);
+    *((int32_t *)(island->instructions + kJumpAddress)) = addressOffset; 
+
+    msync( island->instructions, sizeof( kIslandTemplate ), MS_INVALIDATE );
+    return err_none;
+}
+
+#elif defined(__x86_64__)
+static mach_error_t
+setBranchIslandTarget_i386(
+        BranchIsland	*island,
+        const void		*branchTo,
+        char*			instructions )
+{
+    // Copy over the template code.
+    bcopy( kIslandTemplate, island->instructions, sizeof( kIslandTemplate ) );
+
+    // Copy original instructions.
+    if (instructions) {
+        bcopy (instructions, island->instructions, kOriginalInstructionsSize);
+    }
+
+    //	Fill in the address.
+    *((uint64_t *)(island->instructions + kJumpAddress)) = (uint64_t)branchTo; 
+    msync( island->instructions, sizeof( kIslandTemplate ), MS_INVALIDATE );
+
+    return err_none;
+}
+#endif
+
+
+#if defined(__i386__) || defined(__x86_64__)
+// simplistic instruction matching
+typedef struct {
+	unsigned int length; // max 15
+	unsigned char mask[15]; // sequence of bytes in memory order
+	unsigned char constraint[15]; // sequence of bytes in memory order
+}	AsmInstructionMatch;
+
+#if defined(__i386__)
+static AsmInstructionMatch possibleInstructions[] = {
+	{ 0x5, {0xFF, 0x00, 0x00, 0x00, 0x00}, {0xE9, 0x00, 0x00, 0x00, 0x00} },	// jmp 0x????????
+	{ 0x5, {0xFF, 0xFF, 0xFF, 0xFF, 0xFF}, {0x55, 0x89, 0xe5, 0xc9, 0xc3} },	// push %esp; mov %esp,%ebp; leave; ret
+	{ 0x1, {0xFF}, {0x90} },							// nop
+	{ 0x1, {0xF8}, {0x50} },							// push %reg
+	{ 0x2, {0xFF, 0xFF}, {0x89, 0xE5} },				                // mov %esp,%ebp
+	{ 0x3, {0xFF, 0xFF, 0xFF}, {0x89, 0x1C, 0x24} },				                // mov %ebx,(%esp)
+	{ 0x3, {0xFF, 0xFF, 0x00}, {0x83, 0xEC, 0x00} },	                        // sub 0x??, %esp
+	{ 0x6, {0xFF, 0xFF, 0x00, 0x00, 0x00, 0x00}, {0x81, 0xEC, 0x00, 0x00, 0x00, 0x00} },	// sub 0x??, %esp with 32bit immediate
+	{ 0x2, {0xFF, 0xFF}, {0x31, 0xC0} },						// xor %eax, %eax
+	{ 0x3, {0xFF, 0x4F, 0x00}, {0x8B, 0x45, 0x00} },  // mov $imm(%ebp), %reg
+	{ 0x3, {0xFF, 0x4C, 0x00}, {0x8B, 0x40, 0x00} },  // mov $imm(%eax-%edx), %reg
+	{ 0x3, {0xFF, 0xCF, 0x00}, {0x8B, 0x4D, 0x00} },  // mov $imm(%rpb), %reg
+	{ 0x3, {0xFF, 0x4F, 0x00}, {0x8A, 0x4D, 0x00} },  // mov $imm(%ebp), %cl
+	{ 0x4, {0xFF, 0xFF, 0xFF, 0x00}, {0x8B, 0x4C, 0x24, 0x00} },  			// mov $imm(%esp), %ecx
+	{ 0x4, {0xFF, 0x00, 0x00, 0x00}, {0x8B, 0x00, 0x00, 0x00} },  			// mov r16,r/m16 or r32,r/m32
+	{ 0x5, {0xFF, 0x00, 0x00, 0x00, 0x00}, {0xB9, 0x00, 0x00, 0x00, 0x00} }, 	// mov $imm, %ecx
+	{ 0x5, {0xFF, 0x00, 0x00, 0x00, 0x00}, {0xB8, 0x00, 0x00, 0x00, 0x00} }, 	// mov $imm, %eax
+	{ 0x4, {0xFF, 0xFF, 0xFF, 0x00}, {0x66, 0x0F, 0xEF, 0x00} },             	// pxor xmm2/128, xmm1
+	{ 0x2, {0xFF, 0xFF}, {0xDB, 0xE3} }, 						// fninit
+	{ 0x5, {0xFF, 0x00, 0x00, 0x00, 0x00}, {0xE8, 0x00, 0x00, 0x00, 0x00} },	// call $imm
+	{ 0x4, {0xFF, 0xFF, 0xFF, 0x00}, {0x0F, 0xBE, 0x55, 0x00} },                    // movsbl $imm(%ebp), %edx
+	{ 0x0, {0x00}, {0x00} }
+};
+#elif defined(__x86_64__)
+// TODO(glider): disassembling the "0x48, 0x89" sequences is trickier than it's done below.
+// If it stops working, refer to http://ref.x86asm.net/geek.html#modrm_byte_32_64 to do it
+// more accurately.
+// Note: 0x48 is in fact the REX.W prefix, but it might be wrong to treat it as a separate
+// instruction.
+static AsmInstructionMatch possibleInstructions[] = {
+	{ 0x5, {0xFF, 0x00, 0x00, 0x00, 0x00}, {0xE9, 0x00, 0x00, 0x00, 0x00} },	// jmp 0x????????
+	{ 0x1, {0xFF}, {0x90} },							// nop
+	{ 0x1, {0xF8}, {0x50} },							// push %rX
+	{ 0x1, {0xFF}, {0x65} },							// GS prefix
+	{ 0x3, {0xFF, 0xFF, 0xFF}, {0x48, 0x89, 0xE5} },				// mov %rsp,%rbp
+	{ 0x4, {0xFF, 0xFF, 0xFF, 0x00}, {0x48, 0x83, 0xEC, 0x00} },	                // sub 0x??, %rsp
+	{ 0x4, {0xFB, 0xFF, 0x07, 0x00}, {0x48, 0x89, 0x05, 0x00} },	                // move onto rbp
+	{ 0x3, {0xFB, 0xFF, 0x00}, {0x48, 0x89, 0x00} },	                            // mov %reg, %reg
+	{ 0x3, {0xFB, 0xFF, 0x00}, {0x49, 0x89, 0x00} },	                            // mov %reg, %reg (REX.WB)
+	{ 0x2, {0xFF, 0x00}, {0x41, 0x00} },						// push %rXX
+	{ 0x2, {0xFF, 0x00}, {0x84, 0x00} },						// test %rX8,%rX8
+	{ 0x2, {0xFF, 0x00}, {0x85, 0x00} },						// test %rX,%rX
+	{ 0x2, {0xFF, 0x00}, {0x77, 0x00} },						// ja $i8
+	{ 0x2, {0xFF, 0x00}, {0x74, 0x00} },						// je $i8
+	{ 0x5, {0xF8, 0x00, 0x00, 0x00, 0x00}, {0xB8, 0x00, 0x00, 0x00, 0x00} },	// mov $imm, %reg
+	{ 0x3, {0xFF, 0xFF, 0x00}, {0xFF, 0x77, 0x00} },				// pushq $imm(%rdi)
+	{ 0x2, {0xFF, 0xFF}, {0x31, 0xC0} },						// xor %eax, %eax
+	{ 0x5, {0xFF, 0x00, 0x00, 0x00, 0x00}, {0x25, 0x00, 0x00, 0x00, 0x00} },	// and $imm, %eax
+	{ 0x3, {0xFF, 0xFF, 0xFF}, {0x80, 0x3F, 0x00} },				// cmpb $imm, (%rdi)
+
+  { 0x8, {0xFF, 0xFF, 0xCF, 0xFF, 0x00, 0x00, 0x00, 0x00},
+         {0x48, 0x8B, 0x04, 0x25, 0x00, 0x00, 0x00, 0x00}, },                     // mov $imm, %{rax,rdx,rsp,rsi}
+  { 0x4, {0xFF, 0xFF, 0xFF, 0x00}, {0x48, 0x83, 0xFA, 0x00}, },   // cmp $i8, %rdx
+	{ 0x4, {0xFF, 0xFF, 0x00, 0x00}, {0x83, 0x7f, 0x00, 0x00}, },			// cmpl $imm, $imm(%rdi)
+	{ 0xa, {0xFF, 0xFF, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00},
+               {0x48, 0xB8, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00} },    // mov $imm, %rax
+        { 0x6, {0xFF, 0xFF, 0x00, 0x00, 0x00, 0x00},
+               {0x81, 0xE6, 0x00, 0x00, 0x00, 0x00} },                            // and $imm, %esi
+        { 0x6, {0xFF, 0xFF, 0x00, 0x00, 0x00, 0x00},
+               {0xFF, 0x25, 0x00, 0x00, 0x00, 0x00} },                            // jmpq *(%rip)
+        { 0x4, {0xFF, 0xFF, 0xFF, 0x00}, {0x66, 0x0F, 0xEF, 0x00} },              // pxor xmm2/128, xmm1
+        { 0x2, {0xFF, 0x00}, {0x89, 0x00} },                               // mov r/m32,r32 or r/m16,r16
+        { 0x3, {0xFF, 0xFF, 0xFF}, {0x49, 0x89, 0xF8} },                   // mov %rdi,%r8
+        { 0x4, {0xFF, 0xFF, 0xFF, 0xFF}, {0x40, 0x0F, 0xBE, 0xCE} },       // movsbl %sil,%ecx
+        { 0x7, {0xFF, 0xFF, 0xFF, 0x00, 0x00, 0x00, 0x00},
+               {0x48, 0x8D, 0x05, 0x00, 0x00, 0x00, 0x00} },  // lea $imm(%rip),%rax
+        { 0x3, {0xFF, 0xFF, 0xFF}, {0x0F, 0xBE, 0xCE} },  // movsbl, %dh, %ecx
+        { 0x3, {0xFF, 0xFF, 0x00}, {0xFF, 0x77, 0x00} },  // pushq $imm(%rdi)
+        { 0x2, {0xFF, 0xFF}, {0xDB, 0xE3} }, // fninit
+        { 0x3, {0xFF, 0xFF, 0xFF}, {0x48, 0x85, 0xD2} },  // test %rdx,%rdx
+	{ 0x0, {0x00}, {0x00} }
+};
+#endif
+
+static Boolean codeMatchesInstruction(unsigned char *code, AsmInstructionMatch* instruction) 
+{
+	Boolean match = true;
+	
+	size_t i;
+  assert(instruction);
+#ifdef DEBUG_DISASM
+	fprintf(stderr, "Matching: ");
+#endif  
+	for (i=0; i<instruction->length; i++) {
+		unsigned char mask = instruction->mask[i];
+		unsigned char constraint = instruction->constraint[i];
+		unsigned char codeValue = code[i];
+#ifdef DEBUG_DISASM
+		fprintf(stderr, "%x ", (unsigned)codeValue);
+#endif    
+		match = ((codeValue & mask) == constraint);
+		if (!match) break;
+	}
+#ifdef DEBUG_DISASM
+	if (match) {
+		fprintf(stderr, " OK\n");
+	} else {
+		fprintf(stderr, " FAIL\n");
+	}
+#endif  
+	return match;
+}
+
+#if defined(__i386__) || defined(__x86_64__)
+	static Boolean 
+eatKnownInstructions( 
+	unsigned char	*code, 
+	uint64_t		*newInstruction,
+	int				*howManyEaten, 
+	char			*originalInstructions,
+	int				*originalInstructionCount, 
+	uint8_t			*originalInstructionSizes )
+{
+	Boolean allInstructionsKnown = true;
+	int totalEaten = 0;
+	unsigned char* ptr = code;
+	int remainsToEat = 5; // a JMP instruction takes 5 bytes
+	int instructionIndex = 0;
+	
+	if (howManyEaten) *howManyEaten = 0;
+	if (originalInstructionCount) *originalInstructionCount = 0;
+	while (remainsToEat > 0) {
+		Boolean curInstructionKnown = false;
+		
+		// See if instruction matches one  we know
+		AsmInstructionMatch* curInstr = possibleInstructions;
+		do { 
+			if ((curInstructionKnown = codeMatchesInstruction(ptr, curInstr))) break;
+			curInstr++;
+		} while (curInstr->length > 0);
+		
+		// if all instruction matches failed, we don't know current instruction then, stop here
+		if (!curInstructionKnown) { 
+			allInstructionsKnown = false;
+			fprintf(stderr, "mach_override: some instructions unknown! Need to update mach_override.c\n");
+			break;
+		}
+		
+		// At this point, we've matched curInstr
+		int eaten = curInstr->length;
+		ptr += eaten;
+		remainsToEat -= eaten;
+		totalEaten += eaten;
+		
+		if (originalInstructionSizes) originalInstructionSizes[instructionIndex] = eaten;
+		instructionIndex += 1;
+		if (originalInstructionCount) *originalInstructionCount = instructionIndex;
+	}
+
+
+	if (howManyEaten) *howManyEaten = totalEaten;
+
+	if (originalInstructions) {
+		Boolean enoughSpaceForOriginalInstructions = (totalEaten < kOriginalInstructionsSize);
+		
+		if (enoughSpaceForOriginalInstructions) {
+			memset(originalInstructions, 0x90 /* NOP */, kOriginalInstructionsSize); // fill instructions with NOP
+			bcopy(code, originalInstructions, totalEaten);
+		} else {
+#ifdef DEBUG_DISASM
+			fprintf(stderr, "Not enough space in island to store original instructions. Adapt the island definition and kOriginalInstructionsSize\n");
+#endif      
+			return false;
+		}
+	}
+	
+	if (allInstructionsKnown) {
+		// save last 3 bytes of first 64bits of codre we'll replace
+		uint64_t currentFirst64BitsOfCode = *((uint64_t *)code);
+		currentFirst64BitsOfCode = OSSwapInt64(currentFirst64BitsOfCode); // back to memory representation
+		currentFirst64BitsOfCode &= 0x0000000000FFFFFFLL; 
+		
+		// keep only last 3 instructions bytes, first 5 will be replaced by JMP instr
+		*newInstruction &= 0xFFFFFFFFFF000000LL; // clear last 3 bytes
+		*newInstruction |= (currentFirst64BitsOfCode & 0x0000000000FFFFFFLL); // set last 3 bytes
+	}
+
+	return allInstructionsKnown;
+}
+
+	static void
+fixupInstructions(
+    void		*originalFunction,
+    void		*escapeIsland,
+    void		*instructionsToFix,
+	int			instructionCount,
+	uint8_t		*instructionSizes )
+{
+	void *initialOriginalFunction = originalFunction;
+	int	index, fixed_size, code_size = 0;
+	for (index = 0;index < instructionCount;index += 1)
+		code_size += instructionSizes[index];
+
+#ifdef DEBUG_DISASM
+	void *initialInstructionsToFix = instructionsToFix;
+	fprintf(stderr, "BEFORE FIXING:\n");
+	dump16Bytes(initialOriginalFunction);
+	dump16Bytes(initialInstructionsToFix);
+#endif  // DEBUG_DISASM
+
+	for (index = 0;index < instructionCount;index += 1)
+	{
+                fixed_size = instructionSizes[index];
+		if ((*(uint8_t*)instructionsToFix == 0xE9) || // 32-bit jump relative
+		    (*(uint8_t*)instructionsToFix == 0xE8))   // 32-bit call relative
+		{
+			uint32_t offset = (uintptr_t)originalFunction - (uintptr_t)escapeIsland;
+			uint32_t *jumpOffsetPtr = (uint32_t*)((uintptr_t)instructionsToFix + 1);
+			*jumpOffsetPtr += offset;
+		}
+		if ((*(uint8_t*)instructionsToFix == 0x74) ||  // Near jump if equal (je), 2 bytes.
+		    (*(uint8_t*)instructionsToFix == 0x77))    // Near jump if above (ja), 2 bytes.
+		{
+			// We replace a near je/ja instruction, "7P JJ", with a 32-bit je/ja, "0F 8P WW XX YY ZZ".
+			// This is critical, otherwise a near jump will likely fall outside the original function.
+			uint32_t offset = (uintptr_t)initialOriginalFunction - (uintptr_t)escapeIsland;
+			uint32_t jumpOffset = *(uint8_t*)((uintptr_t)instructionsToFix + 1);
+			*((uint8_t*)instructionsToFix + 1) = *(uint8_t*)instructionsToFix + 0x10;
+			*(uint8_t*)instructionsToFix = 0x0F;
+			uint32_t *jumpOffsetPtr = (uint32_t*)((uintptr_t)instructionsToFix + 2 );
+			*jumpOffsetPtr = offset + jumpOffset;
+			fixed_size = 6;
+                }
+		
+		originalFunction = (void*)((uintptr_t)originalFunction + instructionSizes[index]);
+		escapeIsland = (void*)((uintptr_t)escapeIsland + instructionSizes[index]);
+		instructionsToFix = (void*)((uintptr_t)instructionsToFix + fixed_size);
+
+		// Expanding short instructions into longer ones may overwrite the next instructions,
+		// so we must restore them.
+		code_size -= fixed_size;
+		if ((code_size > 0) && (fixed_size != instructionSizes[index])) {
+			bcopy(originalFunction, instructionsToFix, code_size);
+		}
+	}
+#ifdef DEBUG_DISASM
+	fprintf(stderr, "AFTER_FIXING:\n");
+	dump16Bytes(initialOriginalFunction);
+	dump16Bytes(initialInstructionsToFix);
+#endif  // DEBUG_DISASM
+}
+
+#ifdef DEBUG_DISASM
+#define HEX_DIGIT(x) ((((x) % 16) < 10) ? ('0' + ((x) % 16)) : ('A' + ((x) % 16 - 10)))
+
+	static void
+dump16Bytes(
+	void 	*ptr) {
+	int i;
+	char buf[3];
+	uint8_t *bytes = (uint8_t*)ptr;
+	for (i = 0; i < 16; i++) {
+		buf[0] = HEX_DIGIT(bytes[i] / 16);
+		buf[1] = HEX_DIGIT(bytes[i] % 16);
+		buf[2] = ' ';
+		write(2, buf, 3);
+	}
+	write(2, "\n", 1);
+}
+#endif  // DEBUG_DISASM
+#endif
+
+#if defined(__i386__)
+__asm(
+			".text;"
+			".align 2, 0x90;"
+			"_atomic_mov64:;"
+			"	pushl %ebp;"
+			"	movl %esp, %ebp;"
+			"	pushl %esi;"
+			"	pushl %ebx;"
+			"	pushl %ecx;"
+			"	pushl %eax;"
+			"	pushl %edx;"
+	
+			// atomic push of value to an address
+			// we use cmpxchg8b, which compares content of an address with 
+			// edx:eax. If they are equal, it atomically puts 64bit value 
+			// ecx:ebx in address. 
+			// We thus put contents of address in edx:eax to force ecx:ebx
+			// in address
+			"	mov		8(%ebp), %esi;"  // esi contains target address
+			"	mov		12(%ebp), %ebx;"
+			"	mov		16(%ebp), %ecx;" // ecx:ebx now contains value to put in target address
+			"	mov		(%esi), %eax;"
+			"	mov		4(%esi), %edx;"  // edx:eax now contains value currently contained in target address
+			"	lock; cmpxchg8b	(%esi);" // atomic move.
+			
+			// restore registers
+			"	popl %edx;"
+			"	popl %eax;"
+			"	popl %ecx;"
+			"	popl %ebx;"
+			"	popl %esi;"
+			"	popl %ebp;"
+			"	ret"
+);
+#elif defined(__x86_64__)
+void atomic_mov64(
+		uint64_t *targetAddress,
+		uint64_t value )
+{
+    *targetAddress = value;
+}
+#endif
+#endif
+#endif  // __APPLE__
--- /dev/null	2012-11-16 10:24:58.000000000 -0500
+++ libsanitizer/interception/mach_override/mach_override.h	2012-11-16 10:26:52.000000000 -0500
@@ -0,0 +1,140 @@ 
+/*******************************************************************************
+	mach_override.h
+		Copyright (c) 2003-2009 Jonathan 'Wolf' Rentzsch: <http://rentzsch.com>
+		Some rights reserved: <http://opensource.org/licenses/mit-license.php>
+
+	***************************************************************************/
+
+/***************************************************************************//**
+	@mainpage	mach_override
+	@author		Jonathan 'Wolf' Rentzsch: <http://rentzsch.com>
+	
+	This package, coded in C to the Mach API, allows you to override ("patch")
+	program- and system-supplied functions at runtime. You can fully replace
+	functions with your implementations, or merely head- or tail-patch the
+	original implementations.
+	
+	Use it by #include'ing mach_override.h from your .c, .m or .mm file(s).
+	
+	@todo	Discontinue use of Carbon's MakeDataExecutable() and
+			CompareAndSwap() calls and start using the Mach equivalents, if they
+			exist. If they don't, write them and roll them in. That way, this
+			code will be pure Mach, which will make it easier to use everywhere.
+			Update: MakeDataExecutable() has been replaced by
+			msync(MS_INVALIDATE). There is an OSCompareAndSwap in libkern, but
+			I'm currently unsure if I can link against it. May have to roll in
+			my own version...
+	@todo	Stop using an entire 4K high-allocated VM page per 28-byte escape
+			branch island. Done right, this will dramatically speed up escape
+			island allocations when they number over 250. Then again, if you're
+			overriding more than 250 functions, maybe speed isn't your main
+			concern...
+	@todo	Add detection of: b, bl, bla, bc, bcl, bcla, bcctrl, bclrl
+			first-instructions. Initially, we should refuse to override
+			functions beginning with these instructions. Eventually, we should
+			dynamically rewrite them to make them position-independent.
+	@todo	Write mach_unoverride(), which would remove an override placed on a
+			function. Must be multiple-override aware, which means an almost
+			complete rewrite under the covers, because the target address can't
+			be spread across two load instructions like it is now since it will
+			need to be atomically updatable.
+	@todo	Add non-rentry variants of overrides to test_mach_override.
+
+	***************************************************************************/
+
+#ifdef __APPLE__
+
+#ifndef		_mach_override_
+#define		_mach_override_
+
+#include <sys/types.h>
+#include <mach/error.h>
+
+#ifdef	__cplusplus
+	extern	"C"	{
+#endif
+
+/**
+	Returned if the function to be overrided begins with a 'mfctr' instruction.
+*/
+#define	err_cannot_override	(err_local|1)
+
+/************************************************************************************//**
+	Dynamically overrides the function implementation referenced by
+	originalFunctionAddress with the implentation pointed to by overrideFunctionAddress.
+	Optionally returns a pointer to a "reentry island" which, if jumped to, will resume
+	the original implementation.
+	
+	@param	originalFunctionAddress			->	Required address of the function to
+												override (with overrideFunctionAddress).
+	@param	overrideFunctionAddress			->	Required address to the overriding
+												function.
+	@param	originalFunctionReentryIsland	<-	Optional pointer to pointer to the
+												reentry island. Can be NULL.
+	@result									<-	err_cannot_override if the original
+												function's implementation begins with
+												the 'mfctr' instruction.
+
+	************************************************************************************/
+
+// We're prefixing mach_override_ptr() with "__asan_" to avoid name conflicts with other
+// mach_override_ptr() implementations that may appear in the client program.
+    mach_error_t
+__asan_mach_override_ptr(
+	void *originalFunctionAddress,
+    const void *overrideFunctionAddress,
+    void **originalFunctionReentryIsland );
+
+// Allow to use custom allocation and deallocation routines with mach_override_ptr().
+// This should help to speed up the things on x86_64.
+typedef mach_error_t island_malloc( void **ptr, size_t size, void *hint );
+typedef mach_error_t island_free( void *ptr );
+
+    mach_error_t
+__asan_mach_override_ptr_custom(
+	void *originalFunctionAddress,
+    const void *overrideFunctionAddress,
+    void **originalFunctionReentryIsland,
+    island_malloc *alloc,
+    island_free *dealloc );
+
+/************************************************************************************//**
+	
+
+	************************************************************************************/
+ 
+#ifdef	__cplusplus
+
+#define MACH_OVERRIDE( ORIGINAL_FUNCTION_RETURN_TYPE, ORIGINAL_FUNCTION_NAME, ORIGINAL_FUNCTION_ARGS, ERR )			\
+	{																												\
+		static ORIGINAL_FUNCTION_RETURN_TYPE (*ORIGINAL_FUNCTION_NAME##_reenter)ORIGINAL_FUNCTION_ARGS;				\
+		static bool ORIGINAL_FUNCTION_NAME##_overriden = false;														\
+		class mach_override_class__##ORIGINAL_FUNCTION_NAME {														\
+		public:																										\
+			static kern_return_t override(void *originalFunctionPtr) {												\
+				kern_return_t result = err_none;																	\
+				if (!ORIGINAL_FUNCTION_NAME##_overriden) {															\
+					ORIGINAL_FUNCTION_NAME##_overriden = true;														\
+					result = mach_override_ptr( (void*)originalFunctionPtr,											\
+												(void*)mach_override_class__##ORIGINAL_FUNCTION_NAME::replacement,	\
+												(void**)&ORIGINAL_FUNCTION_NAME##_reenter );						\
+				}																									\
+				return result;																						\
+			}																										\
+			static ORIGINAL_FUNCTION_RETURN_TYPE replacement ORIGINAL_FUNCTION_ARGS {
+
+#define END_MACH_OVERRIDE( ORIGINAL_FUNCTION_NAME )																	\
+			}																										\
+		};																											\
+																													\
+		err = mach_override_class__##ORIGINAL_FUNCTION_NAME::override((void*)ORIGINAL_FUNCTION_NAME);				\
+	}
+ 
+#endif
+
+#ifdef	__cplusplus
+	}
+#endif
+#endif	//	_mach_override_
+
+#endif  // __APPLE__
Index: libsanitizer/configure.ac
===================================================================
--- libsanitizer/configure.ac	(revision 193562)
+++ libsanitizer/configure.ac	(working copy)
@@ -22,6 +22,12 @@  AC_CANONICAL_SYSTEM
 target_alias=${target_alias-$host_alias}
 AC_SUBST(target_alias)
 
+case "$host" in
+  *-*-darwin*) MACH_OVERRIDE=true ;;
+  *) MACH_OVERRIDE=false ;;
+esac
+AM_CONDITIONAL(USING_MACH_OVERRIDE, $MACH_OVERRIDE)
+
 AM_INIT_AUTOMAKE(foreign)
 AM_ENABLE_MULTILIB(, ..)
 AM_MAINTAINER_MODE
Index: libsanitizer/interception/Makefile.am
===================================================================
--- libsanitizer/interception/Makefile.am	(revision 193562)
+++ libsanitizer/interception/Makefile.am	(working copy)
@@ -14,7 +14,11 @@  interception_files = \
         interception_mac.cc \
         interception_win.cc
 
-libinterception_la_SOURCES = $(interception_files) 
+if USING_MACH_OVERRIDE
+libinterception_la_SOURCES = $(interception_files) mach_override/mach_override.c
+else
+libinterception_la_SOURCES = $(interception_files)
+endif
 
 # Work around what appears to be a GNU make bug handling MAKEFLAGS
 # values defined in terms of make variables, as is the case for CC and
Index: libsanitizer/configure.tgt
===================================================================
--- libsanitizer/configure.tgt	(revision 193562)
+++ libsanitizer/configure.tgt	(working copy)
@@ -22,6 +22,8 @@ 
 case "${target}" in
   x86_64-*-linux* | i?86-*-linux* | sparc*-*-linux*)
 	;;
+  x86_64-*-darwin* | i?86-*-darwin*)
+	;;
   *)
 	UNSUPPORTED=1
 	;;
Index: gcc/config/darwin.h
===================================================================
--- gcc/config/darwin.h	(revision 193562)
+++ gcc/config/darwin.h	(working copy)
@@ -180,6 +180,9 @@  extern GTY(()) int darwin_ms_struct;
     %{L*} %(link_libgcc) %o %{fprofile-arcs|fprofile-generate*|coverage:-lgcov} \
     %{fopenmp|ftree-parallelize-loops=*: \
       %{static|static-libgcc|static-libstdc++|static-libgfortran: libgomp.a%s; : -lgomp } } \
+    %{faddress-sanitizer: \
+      %{static|static-libgcc|static-libgfortran: -framework CoreFoundation -lstdc++ libasan.a%s; \
+      static-libstdc++: -framework CoreFoundation libstdc++.a%s libasan.a%s; : -framework CoreFoundation -lasan } } \
     %{fgnu-tm: \
       %{static|static-libgcc|static-libstdc++|static-libgfortran: libitm.a%s; : -litm } } \
     %{!nostdlib:%{!nodefaultlibs:\