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--- libmalloc/libmalloc-792.80.2/src/malloc.c
+++ libmalloc/libmalloc-283.60.1/src/malloc.c
@@ -21,21 +21,14 @@
  * @APPLE_LICENSE_HEADER_END@
  */
 
-/*
- * Needed for definition of MALLOC_MSL_LITE_WRAPPED_ZONE_FLAGS
- */
-#ifndef MALLOC_ENABLE_MSL_LITE_SPI
-#define MALLOC_ENABLE_MSL_LITE_SPI 1
-#endif // MALLOC_ENABLE_MSL_LITE_SPI
-
 #include "internal.h"
 
-#if MALLOC_TARGET_IOS
+#if TARGET_OS_IPHONE
 // malloc_report(ASL_LEVEL_INFO...) on iOS doesn't show up in the Xcode Console log of the device,
 // but ASL_LEVEL_NOTICE does.  So raising the log level is helpful.
 #undef ASL_LEVEL_INFO
 #define ASL_LEVEL_INFO ASL_LEVEL_NOTICE
-#endif // MALLOC_TARGET_IOS
+#endif // TARGET_OS_IPHONE
 
 #define USE_SLEEP_RATHER_THAN_ABORT 0
 
@@ -54,52 +47,12 @@
  */
 int32_t malloc_num_zones = 0;
 int32_t malloc_num_zones_allocated = 0;
-malloc_zone_t **malloc_zones = (malloc_zone_t **)0xdeaddeaddeaddead;
-
-// TODO: getter and setter rather than direct export so that this can be baked
-// into the cached fastpath checks
+malloc_zone_t **malloc_zones = 0;
 malloc_logger_t *malloc_logger = NULL;
-
-static uint32_t initial_num_zones;
-static malloc_zone_t *initial_scalable_zone;
-#if CONFIG_NANOZONE
-static malloc_zone_t *initial_nano_zone;
-#endif // CONFIG_NANOZONE
-malloc_zone_t *initial_xzone_zone;
-static malloc_zone_t *default_purgeable_zone;
-static bool has_injected_zone0;
-static bool malloc_xzone_enabled = MALLOC_XZONE_ENABLED_DEFAULT;
-#if CONFIG_XZONE_MALLOC && CONFIG_NANOZONE
-static bool malloc_nano_on_xzone = false;
-#endif // CONFIG_XZONE_MALLOC && CONFIG_NANOZONE
-
-typedef enum {
-	MALLOC_XZONE_OVERRIDE_DEFAULT,
-	MALLOC_XZONE_OVERRIDE_DISABLED,
-	MALLOC_XZONE_OVERRIDE_ENABLED,
-} malloc_xzone_override_t;
-
-static malloc_xzone_override_t malloc_xzone_nano_override;
-static malloc_xzone_override_t malloc_nano_on_xzone_override;
+static malloc_zone_t *initial_default_zone = NULL;
 
 unsigned malloc_debug_flags = 0;
-bool malloc_tracing_enabled = false;
-bool malloc_space_efficient_enabled = false;
-bool malloc_medium_space_efficient_enabled = true;
-
-bool malloc_sanitizer_enabled = false;
-
-bool malloc_interposition_compat = false;
-
-#if CONFIG_MTE
-bool malloc_has_sec_transition = false;
-uint32_t malloc_sec_transition_policy = 0;
-bool malloc_sec_transition_early_malloc_support = false;
-#endif
-
-#if CONFIG_MALLOC_PROCESS_IDENTITY
-malloc_process_identity_t malloc_process_identity = MALLOC_PROCESS_NONE;
-#endif // CONFIG_MALLOC_PROCESS_IDENTITY
+boolean_t malloc_tracing_enabled = false;
 
 unsigned malloc_check_start = 0; // 0 means don't check
 unsigned malloc_check_counter = 0;
@@ -107,40 +60,43 @@
 
 static int malloc_check_sleep = 100; // default 100 second sleep
 static int malloc_check_abort = 0;   // default is to sleep, not abort
-static bool malloc_simple_stack_logging = false;
-#define MALLOC_SIMPLE_STACK_LOGGING_FLAGS \
-		(ASL_LEVEL_NOTICE | MALLOC_REPORT_NOPREFIX | MALLOC_REPORT_BACKTRACE | MALLOC_REPORT_NOWRITE)
-
-bool malloc_slowpath = false;
-
-static struct _malloc_msl_symbols msl = {};
-
-static struct malloc_sanitizer_poison *sanitizer = NULL;
-
-#if CONFIG_SANITIZER && TARGET_OS_OSX
-// Fallback pointers for memory poisoning functions from upstream ASan runtime
-static struct {
-	void (*memory_poison)(uintptr_t ptr, size_t sz);
-	void (*memory_unpoison)(uintptr_t ptr, size_t sz);
-} sanitizer_fallback_ptrs;
-
-// Fallback structure for heap allocation functions from our ASan runtime
-static struct malloc_sanitizer_poison sanitizer_fallback = {0};
-
-static void malloc_sanitizer_fallback_allocate_poison(uintptr_t ptr, size_t leftrz_sz, size_t alloc_sz, size_t rightrz_sz);
-static void malloc_sanitizer_fallback_deallocate_poison(uintptr_t ptr, size_t sz);
-#endif
-/* These masks are exported for libdispatch to register with (see "internal.h") */
-unsigned long malloc_memorypressure_mask_default_4libdispatch = MALLOC_MEMORYPRESSURE_MASK_DEFAULT;
-unsigned long malloc_memorypressure_mask_msl_4libdispatch = MALLOC_MEMORYPRESSURE_MASK_MSL;
-
-#if MALLOC_TARGET_IOS || TARGET_OS_SIMULATOR
-static unsigned long malloc_memorystatus_mask_resource_exception_handling = 0;
-#else
-static unsigned long malloc_memorystatus_mask_resource_exception_handling = MALLOC_MEMORYSTATUS_MASK_RESOURCE_EXCEPTION_HANDLING;
-#endif
-
-MALLOC_NOEXPORT malloc_zone_t* lite_zone = NULL;
+
+static os_once_t _malloc_initialize_pred;
+
+static
+struct msl {
+	void *dylib;
+
+	void (*handle_memory_event) (unsigned long event);
+	boolean_t (*stack_logging_locked) (void);
+	void (*fork_prepare) (void);
+	void (*fork_parent) (void);
+	void (*fork_child) (void);
+	
+	
+	// TODO delete these ones
+	kern_return_t (*get_frames_for_address)(task_t task,
+											mach_vm_address_t address,
+											mach_vm_address_t *stack_frames_buffer,
+											uint32_t max_stack_frames,
+											uint32_t *count);
+	
+	uint64_t (*stackid_for_vm_region) (task_t task, mach_vm_address_t address);
+	
+	kern_return_t (*get_frames_for_stackid) (task_t task,
+											 uint64_t stack_identifier,
+											 mach_vm_address_t *stack_frames_buffer,
+											 uint32_t max_stack_frames,
+											 uint32_t *count,
+											 bool *last_frame_is_threadid);
+	
+	
+	kern_return_t (*uniquing_table_read_stack) (struct backtrace_uniquing_table *uniquing_table,
+												uint64_t stackid,
+												mach_vm_address_t *out_frames_buffer,
+												uint32_t *out_frames_count,
+												uint32_t max_frames);
+} msl = {};
 
 /*
  * Counters that coordinate zone destruction (in malloc_zone_unregister) with
@@ -160,7 +116,6 @@
 #define MALLOC_LOG_TYPE_CLEARED stack_logging_flag_cleared
 
 #define DEFAULT_MALLOC_ZONE_STRING "DefaultMallocZone"
-#define DEFAULT_SCALABLE_ZONE_STRING "DefaultScalableMallocZone"
 #define DEFAULT_PUREGEABLE_ZONE_STRING "DefaultPurgeableMallocZone"
 #define MALLOC_HELPER_ZONE_STRING "MallocHelperZone"
 
@@ -170,53 +125,19 @@
 MALLOC_NOEXPORT
 unsigned int logical_ncpus;
 
-#if CONFIG_CLUSTER_AWARE
-MALLOC_NOEXPORT
-unsigned int ncpuclusters;
-#endif // CONFIG_CLUSTER_AWARE
-
 MALLOC_NOEXPORT
 unsigned int hyper_shift;
 
-MALLOC_NOEXPORT
-size_t malloc_absolute_max_size;
-
 // Boot argument for max magazine control
 static const char max_magazines_boot_arg[] = "malloc_max_magazines";
 
 static const char large_expanded_cache_threshold_boot_arg[] = "malloc_large_expanded_cache_threshold";
-
-
-MALLOC_NOEXPORT
-unsigned malloc_zero_on_free_sample_period = 0; // 0 means don't sample
-
-static const char zero_on_free_sample_period_boot_arg[] = "malloc_zero_on_free_sample_period";
-
-MALLOC_NOEXPORT
-malloc_zero_policy_t malloc_zero_policy = MALLOC_ZERO_POLICY_DEFAULT;
-
-static const char zero_on_free_enabled_boot_arg[] = "malloc_zero_on_free_enabled";
-
-#if CONFIG_XZONE_MALLOC
-static const char secure_allocator_boot_arg[] = "malloc_secure_allocator";
-
-static
-bool xzm_create_mzones = true;
-
-static
-bool purgeable_zone_use_xzm = true;
-#endif // CONFIG_XZONE_MALLOC
 
 #if CONFIG_MEDIUM_ALLOCATOR
 static const char medium_enabled_boot_arg[] = "malloc_medium_zone";
 static const char max_medium_magazines_boot_arg[] = "malloc_max_medium_magazines";
 static const char medium_activation_threshold_boot_arg[] = "malloc_medium_activation_threshold";
-static const char medium_space_efficient_boot_arg[] = "malloc_medium_space_efficient";
-static const char medium_madvise_dram_scale_divisor_boot_arg[] = "malloc_medium_madvise_dram_scale_divisor";
 #endif // CONFIG_MEDIUM_ALLOCATOR
-
-static
-bool malloc_report_config = false;
 
 /*********	Utilities	************/
 static bool _malloc_entropy_initialized;
@@ -227,32 +148,14 @@
 typedef void * (*dlopen_t) (const char * __path, int __mode);
 typedef void * (*dlsym_t) (void * __handle, const char * __symbol);
 
-static dlopen_t LIBMALLOC_FUNCTION_PTRAUTH(_dlopen) = NULL;
-static dlsym_t LIBMALLOC_FUNCTION_PTRAUTH(_dlsym) = NULL;
+static dlopen_t _dlopen = NULL;
+static dlsym_t _dlsym = NULL;
 #else
 #define _dlopen(...) NULL
 #define _dlsym(...) NULL
 #endif // TARGET_OS_DRIVERKIT
 
-void
-malloc_slowpath_update(void)
-{
-	bool slowpath = has_injected_zone0 ||
-			malloc_num_zones == 0 ||
-			malloc_check_start ||
-			lite_zone ||
-			malloc_tracing_enabled ||
-			malloc_simple_stack_logging ||
-			(malloc_debug_flags & MALLOC_DO_SCRIBBLE) != 0 ||
-			malloc_interposition_compat;
-
-	if (malloc_slowpath != slowpath) {
-		malloc_slowpath = slowpath;
-	}
-}
-
 void __malloc_init(const char *apple[]);
-static void _malloc_initialize(const char *apple[], const char *bootargs);
 
 static int
 __entropy_from_kernel(const char *str)
@@ -282,32 +185,6 @@
 		}
 	}
 	return idx;
-}
-
-#if TARGET_OS_OSX && defined(__x86_64__)
-static uint64_t
-__is_translated(void)
-{
-	return (*(uint64_t*)_COMM_PAGE_CPU_CAPABILITIES64) & kIsTranslated;
-}
-#endif /* TARGET_OS_OSX */
-
-#define LIBMALLOC_EXPERIMENT_FACTORS_KEY "MallocExperiment="
-#define LIBMALLOC_EXPERIMENT_DISABLE_MEDIUM (1ULL)
-#define LIBMALLOC_DEFERRED_RECLAIM_ENABLE "MallocDeferredReclaim=1"
-static void
-__malloc_init_experiments(const char *str)
-{
-	uint64_t experiment_factors = 0;
-	str = strchr(str, '=');
-	if (str) {
-		experiment_factors = strtoull_l(str + 1, NULL, 16, NULL);
-	}
-	switch (experiment_factors) {
-	case LIBMALLOC_EXPERIMENT_DISABLE_MEDIUM:
-		magazine_medium_enabled = false;
-		break;
-	}
 }
 
 static void
@@ -345,58 +222,7 @@
 		}
 	}
 
-	flag = malloc_common_value_for_key_copy(bootargs,
-			zero_on_free_enabled_boot_arg, value_buf, sizeof(value_buf));
-	if (flag) {
-		const char *endp;
-		long value = malloc_common_convert_to_long(flag, &endp);
-		if (!*endp && (value == 0 || value == 1)) {
-			malloc_zero_policy = value ? MALLOC_ZERO_ON_FREE : MALLOC_ZERO_NONE;
-		} else {
-			malloc_report(ASL_LEVEL_ERR,
-					"malloc_zero_on_free_enabled must be 0 or 1 - ignored.\n");
-		}
-	}
-
-	flag = malloc_common_value_for_key_copy(bootargs,
-			zero_on_free_sample_period_boot_arg, value_buf, sizeof(value_buf));
-	if (flag) {
-		const char *endp;
-		long value = malloc_common_convert_to_long(flag, &endp);
-		if (!*endp && value >= 0) {
-			malloc_zero_on_free_sample_period = (unsigned int)value;
-		} else {
-			malloc_report(ASL_LEVEL_ERR,
-					"malloc_zero_on_free_sample_period must be positive - ignored.\n");
-		}
-	}
-
-#if CONFIG_XZONE_MALLOC
-	flag = malloc_common_value_for_key_copy(bootargs,
-			secure_allocator_boot_arg, value_buf, sizeof(value_buf));
-	if (flag) {
-		const char *endp;
-		long value = malloc_common_convert_to_long(flag, &endp);
-		if (!*endp && (value == 0 || value == 1)) {
-			malloc_xzone_enabled = (bool)value;
-		} else {
-			malloc_report(ASL_LEVEL_ERR,
-					"malloc_secure_allocator must be 0 or 1 - ignored.\n");
-		}
-	}
-#endif // CONFIG_XZONE_MALLOC
-
 #if CONFIG_MEDIUM_ALLOCATOR
-#if TARGET_OS_OSX
-#if defined(__x86_64__)
-	if (__is_translated()) {
-		magazine_medium_active_threshold = 0;
-	}
-#elif defined(__arm64__)
-	magazine_medium_active_threshold = 0;
-#endif
-#endif /* TARGET_OS_OSX */
-
 	flag = malloc_common_value_for_key_copy(bootargs, medium_enabled_boot_arg,
 			value_buf, sizeof(value_buf));
 	if (flag) {
@@ -432,367 +258,10 @@
 					"malloc_max_medium_magazines must be positive - ignored.\n");
 		}
 	}
-
-	flag = malloc_common_value_for_key_copy(bootargs,
-			medium_space_efficient_boot_arg, value_buf, sizeof(value_buf));
-	if (flag) {
-		const char *endp;
-		long value = malloc_common_convert_to_long(flag, &endp);
-		if (!*endp) {
-			malloc_medium_space_efficient_enabled = (value != 0);
-		}
-	}
-
-	flag = malloc_common_value_for_key_copy(bootargs, medium_madvise_dram_scale_divisor_boot_arg, value_buf, sizeof(value_buf));
-	if (flag) {
-		const char *endp;
-		long value = malloc_common_convert_to_long(flag, &endp);
-		if (!*endp && value >= 0) {
-			magazine_medium_madvise_dram_scale_divisor = (uint64_t)value;
-		} else {
-			malloc_report(ASL_LEVEL_ERR,
-					"malloc_medium_madvise_dram_scale_divisor must be positive - ignored.\n");
-		}
-	}
 #endif // CONFIG_MEDIUM_ALLOCATOR
 }
 
-#if CONFIG_MALLOC_PROCESS_IDENTITY
-
-static void
-_malloc_check_process_identity(const char *apple[])
-{
-	static const struct {
-		const char *name;
-		malloc_process_identity_t identity;
-	} name_identity_mapping[] = {
-#if TARGET_OS_SIMULATOR
-		{ "launchd_sim",             MALLOC_PROCESS_LAUNCHD, },
-		{ "launchd_sim.development", MALLOC_PROCESS_LAUNCHD, },
-		{ "launchd_sim.debug",       MALLOC_PROCESS_LAUNCHD, },
-#else // TARGET_OS_SIMULATOR
-		{ "launchd",             MALLOC_PROCESS_LAUNCHD, },
-		{ "launchd.development", MALLOC_PROCESS_LAUNCHD, },
-		{ "launchd.debug",       MALLOC_PROCESS_LAUNCHD, },
-		{ "launchd.testing",     MALLOC_PROCESS_LAUNCHD, },
-#endif // TARGET_OS_SIMULATOR
-		{ "logd",                MALLOC_PROCESS_LOGD, },
-		{ "notifyd",             MALLOC_PROCESS_NOTIFYD, },
-
-		{ "mediaparserd",        MALLOC_PROCESS_MEDIAPARSERD, },
-		{ "videocodecd",         MALLOC_PROCESS_VIDEOCODECD, },
-		{ "mediaplaybackd",      MALLOC_PROCESS_MEDIAPLAYBACKD },
-		{ "audiomxd",            MALLOC_PROCESS_AUDIOMXD, },
-		{ "avconferenced",       MALLOC_PROCESS_AVCONFERENCED, },
-		{ "mediaserverd",        MALLOC_PROCESS_MEDIASERVERD, },
-		{ "cameracaptured",      MALLOC_PROCESS_CAMERACAPTURED, },
-
-		{ "MessagesBlastDoorService", MALLOC_PROCESS_BLASTDOOR_MESSAGES, },
-		{ "MessagesAirlockService",   MALLOC_PROCESS_BLASTDOOR_MESSAGES, },
-		{ "IDSBlastDoorService",      MALLOC_PROCESS_BLASTDOOR_IDS, },
-		{ "IMDPersistenceAgent",      MALLOC_PROCESS_IMDPERSISTENCEAGENT },
-		{ "imagent",                  MALLOC_PROCESS_IMAGENT, },
-
-		{ "ThumbnailExtensionSecure", MALLOC_PROCESS_QUICKLOOK_THUMBNAIL_SECURE, },
-		{ "com.apple.quicklook.extension.previewUI", MALLOC_PROCESS_QUICKLOOK_PREVIEW, },
-		{ "QuickLookUIExtension",     MALLOC_PROCESS_QUICKLOOK_PREVIEW, },
-		{ "ThumbnailExtension",       MALLOC_PROCESS_QUICKLOOK_THUMBNAIL },
-#if TARGET_OS_OSX
-		// Load-bearing: not already MallocSpaceEfficient
-		{ "QuickLookUIService",       MALLOC_PROCESS_QUICKLOOK_UISERVICE },
-		// Already MallocSpaceEfficient, but valuable to identify as
-		// security-relevant for other special treatment
-		{ "ThumbnailExtension_macOS", MALLOC_PROCESS_QUICKLOOK_THUMBNAIL },
-		{ "QuickLookSatellite",       MALLOC_PROCESS_QUICKLOOK_MACOS },
-		{ "quicklookd",               MALLOC_PROCESS_QUICKLOOK_MACOS },
-		{ "com.apple.quicklook.ThumbnailsAgent", MALLOC_PROCESS_QUICKLOOK_MACOS },
-		{ "ExternalQuickLookSatellite-arm64",    MALLOC_PROCESS_QUICKLOOK_MACOS },
-		{ "ExternalQuickLookSatellite-x86_64",   MALLOC_PROCESS_QUICKLOOK_MACOS },
-#endif // TARGET_OS_OSX
-
-		{ "MobileSafari",                                          MALLOC_PROCESS_BROWSER, },
-		{ "com.apple.WebKit.Networking",                           MALLOC_PROCESS_BROWSER, },
-		{ "com.apple.WebKit.Networking.Development",               MALLOC_PROCESS_BROWSER, },
-		{ "com.apple.WebKit.GPU",                                  MALLOC_PROCESS_BROWSER, },
-		{ "com.apple.WebKit.GPU.Development",                      MALLOC_PROCESS_BROWSER, },
-		{ "com.apple.WebKit.WebContent",                           MALLOC_PROCESS_BROWSER, },
-		{ "com.apple.WebKit.WebContent.Development",               MALLOC_PROCESS_BROWSER, },
-		{ "com.apple.WebKit.WebContent.CaptivePortal",             MALLOC_PROCESS_BROWSER, },
-		{ "com.apple.WebKit.WebContent.CaptivePortal.Development", MALLOC_PROCESS_BROWSER, },
-		{ "com.apple.WebKit.WebContent.EnhancedSecurity",             MALLOC_PROCESS_BROWSER, },
-		{ "com.apple.WebKit.WebContent.EnhancedSecurity.Development", MALLOC_PROCESS_BROWSER, },
-
-		{ "MTLCompilerService",          MALLOC_PROCESS_MTLCOMPILERSERVICE },
-
-#if TARGET_OS_OSX
-		{ "Safari",                                      MALLOC_PROCESS_SAFARI, },
-		{ "com.apple.Safari.CredentialExtractionHelper", MALLOC_PROCESS_SAFARI_SUPPORT, },
-		{ "com.apple.Safari.History",                    MALLOC_PROCESS_SAFARI_SUPPORT, },
-		{ "com.apple.Safari.SandboxBroker",              MALLOC_PROCESS_SAFARI_SUPPORT, },
-		{ "com.apple.Safari.SearchHelper",               MALLOC_PROCESS_SAFARI_SUPPORT, },
-		{ "com.apple.SafariFoundation.CredentialProviderExtensionHelper", MALLOC_PROCESS_SAFARI_SUPPORT, },
-		{ "com.apple.SafariPlatformSupport.Helper",      MALLOC_PROCESS_SAFARI_SUPPORT, },
-		{ "com.apple.SafariServices.ExtensionHelper",    MALLOC_PROCESS_SAFARI_SUPPORT, },
-		{ "com.apple.SafariServices",                    MALLOC_PROCESS_SAFARI_SUPPORT, },
-		{ "VTDecoderXPCService",                         MALLOC_PROCESS_VTDECODERXPCSERVICE, },
-#endif // TARGET_OS_OSX
-
-		{ "callservicesd",       MALLOC_PROCESS_CALLSERVICESD, },
-		{ "maild",               MALLOC_PROCESS_MAILD, },
-		{ "mDNSResponder",       MALLOC_PROCESS_MDNSRESPONDER, },
-		{ "ASVAssetViewer",      MALLOC_PROCESS_ASVASSETVIEWER },
-		{ "identityservicesd",   MALLOC_PROCESS_IDENTITYSERVICESD, },
-		{ "wifid",               MALLOC_PROCESS_WIFID, },
-		{ "fmfd",                MALLOC_PROCESS_FMFD, },
-		{ "searchpartyd",        MALLOC_PROCESS_SEARCHPARTYD, },
-		{ "vmd",                 MALLOC_PROCESS_VMD, },
-		{ "CommCenter",          MALLOC_PROCESS_COMMCENTER, },
-		{ "wifip2pd",            MALLOC_PROCESS_WIFIP2PD, },
-		{ "wifianalyticsd",      MALLOC_PROCESS_WIFIANALYTICSD, },
-
-#if TARGET_OS_VISION
-		{ "presenced",           MALLOC_PROCESS_PRESENCED, },
-		{ "FaceTime",            MALLOC_PROCESS_FACETIME, },
-		{ "managedassetsd",      MALLOC_PROCESS_MANAGEDASSETSD },
-		{ "polarisd",            MALLOC_PROCESS_POLARISD },
-		{ "arkitd",              MALLOC_PROCESS_ARKITD, },
-		{ "backboardd",          MALLOC_PROCESS_BACKBOARDD, },
-		{ "wakeboardd",          MALLOC_PROCESS_WAKEBOARDD, },
-		{ "realitycamerad",      MALLOC_PROCESS_REALITYCAMERAD, },
-#endif // TARGET_OS_VISION
-
-		{ "AegirPoster",         MALLOC_PROCESS_AEGIRPOSTER, },
-		{ "CollectionsPoster",   MALLOC_PROCESS_COLLECTIONSPOSTER, },
-
-#if TARGET_OS_WATCH
-		{ "backboardd",          MALLOC_PROCESS_BACKBOARDD, },
-		{ "ClockFace",           MALLOC_PROCESS_CLOCKFACE, },
-#endif // TARGET_OS_WATCH
-
-#if TARGET_OS_OSX
-		{ "GroupSessionService", MALLOC_PROCESS_GROUPSESSIONSERVICE, },
-		{ "IMTranscoderAgent", MALLOC_PROCESS_IMTRANSCODERAGENT, },
-		{ "Messages", MALLOC_PROCESS_MESSAGES, },
-		{ "Screen Sharing", MALLOC_PROCESS_SCREENSHARING, },
-		{ "keychainsharingmessagingd", MALLOC_PROCESS_KEYCHAINSHARINGMESSAGINGD, },
-
-		{ "VTEncoderXPCService", MALLOC_PROCESS_VTENCODERXPCSERVICE, },
-#endif // TARGET_OS_OSX
-
-		{ "ReportCrash", MALLOC_PROCESS_REPORTCRASH, },
-		{ "AudioConverterService", MALLOC_PROCESS_AUDIOCONVERTERSERVICE, },
-
-	};
-
-	if (getpid() == 1) {
-		malloc_process_identity = MALLOC_PROCESS_LAUNCHD;
-		return;
-	}
-
-	const char *flag = _simple_getenv(apple, "HardenedRuntime");
-	if (flag) {
-		unsigned long long value = strtoull(flag, NULL, 0);
-		if (value) {
-			// reproduced from xnu
-			enum {
-				MallocBrowserHostEntitlementMask       = 0x01,
-				MallocBrowserGPUEntitlementMask        = 0x02,
-				MallocBrowserNetworkEntitlementMask    = 0x04,
-				MallocBrowserWebContentEntitlementMask = 0x08,
-			};
-
-			long enablement_mask = MallocBrowserHostEntitlementMask |
-					MallocBrowserGPUEntitlementMask |
-					MallocBrowserNetworkEntitlementMask |
-					MallocBrowserWebContentEntitlementMask;
-			if (value & enablement_mask) {
-				malloc_process_identity = MALLOC_PROCESS_BROWSER;
-				return;
-			}
-		}
-	}
-
-	const char *name = getprogname();
-	for (size_t i = 0; i < countof(name_identity_mapping); i++) {
-		if (!strcmp(name, name_identity_mapping[i].name)) {
-			malloc_process_identity = name_identity_mapping[i].identity;
-			return;
-		}
-	}
-
-	if (os_security_config_get() & OS_SECURITY_CONFIG_HARDENED_HEAP) {
-		malloc_process_identity = MALLOC_PROCESS_HARDENED_HEAP_CONFIG;
-	}
-}
-
-#if !CONFIG_FEATUREFLAGS_SIMPLE
-#error "must have feature flags"
-#endif
-
-static bool
-_malloc_check_secure_allocator_process_enablement(
-		malloc_process_identity_t identity)
-{
-	// launchd is special because the feature flag check can't work for it
-	if (identity == MALLOC_PROCESS_LAUNCHD) {
-		return MALLOC_SECURE_ALLOCATOR_LAUNCHD_ENABLED_DEFAULT;
-	}
-
-#define ENABLEMENT_CASE(id, enable_status) \
-		case MALLOC_PROCESS_##id: \
-			return (enable_status);
-#define ENABLEMENT_CASE_FF(id, name, darwin_default, simulator_default) \
-		case MALLOC_PROCESS_##id: \
-			return malloc_secure_feature_enabled(SecureAllocator_process_##name, \
-					(darwin_default), (simulator_default))
-
-
-	switch (identity) {
-	ENABLEMENT_CASE(LOGD, true);
-	ENABLEMENT_CASE(NOTIFYD, true);
-
-	ENABLEMENT_CASE(MEDIAPARSERD, true);
-	ENABLEMENT_CASE(VIDEOCODECD, true);
-	ENABLEMENT_CASE(MEDIAPLAYBACKD, true);
-	ENABLEMENT_CASE(AVCONFERENCED, true);
-	ENABLEMENT_CASE(MEDIASERVERD, true);
-	ENABLEMENT_CASE(AUDIOMXD, true);
-	ENABLEMENT_CASE(CAMERACAPTURED, true);
-
-	ENABLEMENT_CASE(BLASTDOOR_MESSAGES, true);
-	ENABLEMENT_CASE(BLASTDOOR_IDS, true);
-	ENABLEMENT_CASE(IMDPERSISTENCEAGENT, true);
-	ENABLEMENT_CASE(IMAGENT, true);
-
-#if TARGET_OS_OSX
-	ENABLEMENT_CASE(QUICKLOOK_MACOS, true);
-	ENABLEMENT_CASE(QUICKLOOK_UISERVICE, true);
-#endif
-	ENABLEMENT_CASE(QUICKLOOK_THUMBNAIL_SECURE, true);
-	ENABLEMENT_CASE(QUICKLOOK_PREVIEW, true);
-	ENABLEMENT_CASE(QUICKLOOK_THUMBNAIL, true);
-
-	ENABLEMENT_CASE(MTLCOMPILERSERVICE, true);
-
-	ENABLEMENT_CASE(CALLSERVICESD, true);
-	ENABLEMENT_CASE(MAILD, true);
-	ENABLEMENT_CASE(MDNSRESPONDER, true);
-	ENABLEMENT_CASE(ASVASSETVIEWER, true);
-	ENABLEMENT_CASE(IDENTITYSERVICESD, true);
-	ENABLEMENT_CASE(WIFID, true);
-	ENABLEMENT_CASE(FMFD, true);
-	ENABLEMENT_CASE(SEARCHPARTYD, true);
-	ENABLEMENT_CASE(VMD, true);
-	ENABLEMENT_CASE(WIFIP2PD, true);
-	ENABLEMENT_CASE(WIFIANALYTICSD, true);
-
-	ENABLEMENT_CASE(COMMCENTER, true);
-
-#if TARGET_OS_SIMULATOR
-	ENABLEMENT_CASE(BROWSER, false);
-#else
-	ENABLEMENT_CASE(BROWSER, true);
-#endif // TARGET_OS_SIMULATOR
-
-#if TARGET_OS_OSX
-	ENABLEMENT_CASE(SAFARI, true);
-	ENABLEMENT_CASE(SAFARI_SUPPORT, true);
-#endif
-
-#if TARGET_OS_VISION
-	ENABLEMENT_CASE(PRESENCED, true);
-	ENABLEMENT_CASE(FACETIME, true);
-	ENABLEMENT_CASE(MANAGEDASSETSD, true);
-	ENABLEMENT_CASE(POLARISD, true);
-
-	ENABLEMENT_CASE_FF(ARKITD, arkitd, true, true);
-	ENABLEMENT_CASE_FF(BACKBOARDD, backboardd, true, true);
-	ENABLEMENT_CASE_FF(WAKEBOARDD, wakeboardd, true, true);
-	ENABLEMENT_CASE_FF(REALITYCAMERAD, realitycamerad, true, true);
-#endif
-
-	ENABLEMENT_CASE_FF(AEGIRPOSTER, aegirposter, false, false);
-	ENABLEMENT_CASE_FF(COLLECTIONSPOSTER, CollectionsPoster, false, false);
-
-#if TARGET_OS_WATCH
-	ENABLEMENT_CASE_FF(BACKBOARDD, backboardd, false, false);
-	ENABLEMENT_CASE_FF(CLOCKFACE, ClockFace, false, false);
-#endif
-
-#if TARGET_OS_OSX
-	ENABLEMENT_CASE(GROUPSESSIONSERVICE, true);
-	ENABLEMENT_CASE(IMTRANSCODERAGENT, true);
-	ENABLEMENT_CASE(KEYCHAINSHARINGMESSAGINGD, true);
-	ENABLEMENT_CASE(MESSAGES, true);
-	ENABLEMENT_CASE(SCREENSHARING, true);
-#endif
-
-#if TARGET_OS_OSX
-	ENABLEMENT_CASE(VTDECODERXPCSERVICE, true);
-#endif
-
-#if TARGET_OS_OSX
-	ENABLEMENT_CASE_FF(VTENCODERXPCSERVICE, VTEncoderXPCService, false, false);
-#endif
-
-	ENABLEMENT_CASE(REPORTCRASH, true);
-	ENABLEMENT_CASE(AUDIOCONVERTERSERVICE, true);
-
-
-	ENABLEMENT_CASE(HARDENED_HEAP_CONFIG, true);
-
-	default:
-		return false;
-	}
-}
-
-#endif // CONFIG_MALLOC_PROCESS_IDENTITY
-
-static void
-_malloc_init_featureflags(void)
-{
-#if CONFIG_FEATUREFLAGS_SIMPLE
-	bool zero_on_free_feature_enabled = os_feature_enabled_simple(libmalloc,
-			ZeroOnFree, MALLOC_ZERO_POLICY_DEFAULT == MALLOC_ZERO_ON_FREE);
-	bool policy_is_zero_on_free = (malloc_zero_policy == MALLOC_ZERO_ON_FREE);
-	if (zero_on_free_feature_enabled != policy_is_zero_on_free) {
-		malloc_zero_policy = zero_on_free_feature_enabled ?
-				MALLOC_ZERO_ON_FREE : MALLOC_ZERO_NONE;
-	}
-
-	bool secure_allocator = false;
-#if CONFIG_MALLOC_PROCESS_IDENTITY
-	if (malloc_process_identity != MALLOC_PROCESS_NONE) {
-		secure_allocator =
-				_malloc_check_secure_allocator_process_enablement(malloc_process_identity);
-	} else
-#endif // CONFIG_MALLOC_PROCESS_IDENTITY
-	{
-#if MALLOC_TARGET_IOS_ONLY || TARGET_OS_VISION || TARGET_OS_OSX || \
-		TARGET_OS_WATCH
-		secure_allocator = malloc_secure_feature_enabled(
-				SecureAllocator_SystemWide, true, true);
-#else
-		secure_allocator = malloc_secure_feature_enabled(
-				SecureAllocator_SystemWide, false, false);
-#endif	// MALLOC_TARGET_IOS_ONLY || TARGET_OS_VISION || TARGET_OS_OSX
-	}
-
-#if TARGET_OS_OSX && !TARGET_CPU_ARM64
-	if (!os_feature_enabled_simple(libmalloc, SecureAllocator_Intel, false)) {
-		secure_allocator = false;
-	}
-#endif // TARGET_OS_OSX && !TARGET_CPU_ARM64
-
-	if (secure_allocator != malloc_xzone_enabled) {
-		malloc_xzone_enabled = secure_allocator;
-	}
-#endif // CONFIG_FEATUREFLAGS_SIMPLE
-}
-
-extern malloc_zone_t *force_asan_init_if_present(void)
-		asm("_malloc_default_zone");
-
+/* TODO: Investigate adding _malloc_initialize() into this libSystem initializer */
 void
 __malloc_init(const char *apple[])
 {
@@ -801,52 +270,18 @@
 	// to temporarily allocate at least a page of memory to read the bootargs
 	// into.
 	char bootargs[1024] = { '\0' };
-	bool allow_bootargs = true;
-#if CONFIG_FEATUREFLAGS_SIMPLE
-	// os_feature_enabled_simple() doesn't work in launchd, but launchd should
-	// be able to read boot-args
-	if (getpid() != 1) {
-		allow_bootargs &= os_feature_enabled_simple(libmalloc, EnableBootArgs, false);
-	}
-#endif
-#if defined(_COMM_PAGE_DEV_FIRM)
-	allow_bootargs &= !!*((uint32_t *)_COMM_PAGE_DEV_FIRM);
-#endif // _COMM_PAGE_DEV_FIRM
-
 	size_t len = sizeof(bootargs) - 1;
-	if (allow_bootargs &&
-			!sysctlbyname("kern.bootargs", bootargs, &len, NULL, 0) &&
-			len > 0) {
+	if (!sysctlbyname("kern.bootargs", bootargs, &len, NULL, 0) && len > 0) {
 		bootargs[len + 1] = '\0';
 	}
 
-	// Cache the calculation of this "constant", which unfortunately depends on
-	// runtime values of vm_kernel_page_size and vm_page_size
-	malloc_absolute_max_size = _MALLOC_ABSOLUTE_MAX_SIZE;
-
-#if CONFIG_CHECK_PLATFORM_BINARY
-	bool is_platform_binary = _malloc_is_platform_binary();
-	if (malloc_is_platform_binary != is_platform_binary) {
-		malloc_is_platform_binary = is_platform_binary;
-	}
-#endif
-
+#if CONFIG_NANOZONE
 	// TODO: envp should be passed down from Libsystem
 	const char **envp = (const char **)*_NSGetEnviron();
-
-	bool allow_internal_security = _malloc_allow_internal_security_policy(envp);
-	if (allow_internal_security != malloc_internal_security_policy) {
-		malloc_internal_security_policy = allow_internal_security;
-	}
-
-#if CONFIG_MALLOC_PROCESS_IDENTITY
-	_malloc_check_process_identity(apple);
+	nano_common_init(envp, apple, bootargs);
 #endif
 
-	_malloc_init_featureflags();
-
 	const char **p;
-	const char *malloc_experiments = NULL;
 	for (p = apple; p && *p; p++) {
 		if (strstr(*p, "malloc_entropy") == *p) {
 			int count = __entropy_from_kernel(*p);
@@ -855,87 +290,23 @@
 			if (sizeof(malloc_entropy) / sizeof(malloc_entropy[0]) == count) {
 				_malloc_entropy_initialized = true;
 			}
-		}
-		if (strstr(*p, LIBMALLOC_EXPERIMENT_FACTORS_KEY) == *p) {
-			malloc_experiments = *p;
-		}
-#if CONFIG_MAGAZINE_DEFERRED_RECLAIM
-		if (strstr(*p, LIBMALLOC_DEFERRED_RECLAIM_ENABLE) == *p) {
-			// Turn on the large cache which will place
-			// its free entries in the deferred reclaim buffer
-			large_cache_enabled = 1;
-		}
-#endif /* CONFIG_MAGAZINE_DEFERRED_RECLAIM */
+			break;
+		}
 	}
 	if (!_malloc_entropy_initialized) {
 		getentropy((void*)malloc_entropy, sizeof(malloc_entropy));
 		_malloc_entropy_initialized = true;
 	}
 
-	if (malloc_experiments) {
-		__malloc_init_experiments(malloc_experiments);
-	}
 	__malloc_init_from_bootargs(bootargs);
 	mvm_aslr_init();
-
-	/*
-	 * This really is a renamed call to malloc_default_zone() which is
-	 * interposable and interposed by asan, so that we trigger the lazy
-	 * initialization of asan _BEFORE_ _malloc_initialize().
-	 *
-	 * If we do it after, then _malloc_initialize() then ASAN will replace
-	 * the system allocator too late and bad things happen.
-	 */
-	force_asan_init_if_present();
-
-	_malloc_initialize(apple, bootargs);
-}
-
-static void register_pgm_zone(bool internal_diagnostics);
-static void stack_logging_early_finished(const struct _malloc_late_init *funcs);
-
-// WARNING: The passed _malloc_late_init is a stack variable in
-// libSystem_initializer().  We must not hold on to it.
-//
-// WARNING 2: By the time this is called, malloc() is already used
-// a bunch of times (from libobjc, libxpc, ...).
-void
-__malloc_late_init(const struct _malloc_late_init *mli)
-{
-	register_pgm_zone(mli->internal_diagnostics);
-	stack_logging_early_finished(mli);
-	initial_num_zones = malloc_num_zones;
-	
-#if CONFIG_SANITIZER
-	if (malloc_sanitizer_enabled) {
-		sanitizer_reset_environment();
-
-#if TARGET_OS_OSX
-		// Fetch the memory poisoning functions from the upstream ASan runtime
-		sanitizer_fallback_ptrs.memory_poison = _dlsym(RTLD_MAIN_ONLY, "__asan_poison_memory_region");
-		sanitizer_fallback_ptrs.memory_unpoison = _dlsym(RTLD_MAIN_ONLY, "__asan_unpoison_memory_region");
-
-		// Prefer the heap allocation functions from our ASan runtime, if available
-		void *heap_alloc = _dlsym(RTLD_MAIN_ONLY, "__asan_poison_heap_memory_alloc"),
-			 *heap_dealloc = _dlsym(RTLD_MAIN_ONLY, "__asan_poison_heap_memory_free"),
-			 *heap_internal_poison = _dlsym(RTLD_MAIN_ONLY, "__asan_poison_heap_memory_internal");
-		if (heap_alloc && heap_dealloc && heap_internal_poison) {
-			sanitizer_fallback.heap_allocate_poison = heap_alloc;
-			sanitizer_fallback.heap_deallocate_poison = heap_dealloc;
-			sanitizer_fallback.heap_internal_poison = heap_internal_poison;
-		} else {
-			sanitizer_fallback.heap_allocate_poison = &malloc_sanitizer_fallback_allocate_poison;
-			sanitizer_fallback.heap_deallocate_poison = &malloc_sanitizer_fallback_deallocate_poison;
-			sanitizer_fallback.heap_internal_poison = &malloc_sanitizer_fallback_deallocate_poison;
-		}
-#endif
-	}
-#endif
-}
+}
+
+MALLOC_NOEXPORT malloc_zone_t* lite_zone = NULL;
 
 MALLOC_ALWAYS_INLINE
 static inline malloc_zone_t *
-runtime_default_zone(void) {
+runtime_default_zone() {
 	return (lite_zone) ? lite_zone : inline_malloc_default_zone();
 }
 
@@ -1173,18 +544,22 @@
 	default_zone_malloc_claimed_address,
 };
 
-MALLOC_NOEXPORT malloc_zone_t *default_zone = &virtual_default_zone.malloc_zone;
+static malloc_zone_t *default_zone = &virtual_default_zone.malloc_zone;
 
 MALLOC_NOEXPORT
 /*static*/ boolean_t
 has_default_zone0(void)
 {
-	return !has_injected_zone0;
-}
-
-static inline malloc_zone_t *_find_registered_zone(const void *, size_t *, bool) __attribute__((always_inline));
+	if (!malloc_zones) {
+		return false;
+	}
+	
+	return initial_default_zone == malloc_zones[0];
+}
+
+static inline malloc_zone_t *find_registered_zone(const void *, size_t *) __attribute__((always_inline));
 static inline malloc_zone_t *
-_find_registered_zone(const void *ptr, size_t *returned_size, bool known_non_default)
+find_registered_zone(const void *ptr, size_t *returned_size)
 {
 	// Returns a zone which contains ptr, else NULL
 
@@ -1207,37 +582,32 @@
 			return default_zone;
 		}
 	}
-
-	malloc_zone_t *zone;
-	size_t size;
-
-	// We assume that the initial zones will never be unregistered concurrently while this code is running so we can have
-	// a fast path without synchronization.  Callers who really do unregister these (to install their own default zone) need
-	// to ensure they establish their zone setup during initialization and before entering a multi-threaded environment.
-	for (uint32_t i = known_non_default ? 1 : 0; i < initial_num_zones; i++) {
-		zone = malloc_zones[i];
-		size = zone->size(zone, ptr);
-
-		if (size) { // Claimed by this zone?
-			if (returned_size) {
-				*returned_size = size;
-			}
-
-			// Asan and others replace the zone at position 0 with their own zone.
-			// In that case just return that zone as they need this information.
-			// Otherwise return the virtual default zone, not the actual zone in position 0.
-			if (i == 0 && has_default_zone0()) {
-				return default_zone;
-			}
-
+	
+	// The default zone is registered in malloc_zones[0]. There's no danger that it will ever be unregistered.
+	// So don't advance the FRZ counter yet.
+	malloc_zone_t *zone = malloc_zones[0];
+	size_t size = zone->size(zone, ptr);
+	if (size) { // Claimed by this zone?
+		if (returned_size) {
+			*returned_size = size;
+		}
+
+		// Asan and others replace the zone at position 0 with their own zone.
+		// In that case just return that zone as they need this information.
+		// Otherwise return the virtual default zone, not the actual zone in position 0.
+		if (!has_default_zone0()) {
 			return zone;
+		} else {
+			return default_zone;
 		}
 	}
 
 	int32_t volatile *pFRZCounter = pFRZCounterLive;   // Capture pointer to the counter of the moment
 	OSAtomicIncrement32Barrier(pFRZCounter); // Advance this counter -- our thread is in FRZ
 
+	unsigned index;
 	int32_t limit = *(int32_t volatile *)&malloc_num_zones;
+	malloc_zone_t **zones = &malloc_zones[1];
 
 	// From this point on, FRZ is accessing the malloc_zones[] array without locking
 	// in order to avoid contention on common operations (such as non-default-zone free()).
@@ -1254,8 +624,8 @@
 	//      are still valid). It also ensures that all the pointers in the zones array are
 	//      valid until it returns, so that a stale value in limit is not dangerous.
 
-	for (uint32_t i = initial_num_zones; i < limit; i++) {
-		zone = malloc_zones[i];
+	for (index = 1; index < limit; ++index, ++zones) {
+		zone = *zones;
 		size = zone->size(zone, ptr);
 		if (size) { // Claimed by this zone?
 			goto out;
@@ -1270,13 +640,6 @@
 	}
 	OSAtomicDecrement32Barrier(pFRZCounter); // our thread is leaving FRZ
 	return zone;
-}
-
-malloc_zone_t *
-find_registered_zone(const void *ptr, size_t *returned_size,
-		bool known_non_default)
-{
-	return _find_registered_zone(ptr, returned_size, known_non_default);
 }
 
 void
@@ -1326,13 +689,9 @@
 /*********	Creation and destruction	************/
 
 static void set_flags_from_environment(void);
-#if CONFIG_MTE
-static bool _malloc_check_has_sec_transition(const char *apple[]);
-static uint32_t _malloc_get_sec_transition_policy(const char *apple[]);
-#endif
 
 MALLOC_NOEXPORT void
-malloc_zone_register_while_locked(malloc_zone_t *zone, bool make_default)
+malloc_zone_register_while_locked(malloc_zone_t *zone)
 {
 	size_t protect_size;
 	unsigned i;
@@ -1348,30 +707,14 @@
 
 	if (malloc_num_zones == malloc_num_zones_allocated) {
 		size_t malloc_zones_size = malloc_num_zones * sizeof(malloc_zone_t *);
-
-		size_t new_malloc_num_zones_allocated = 0;
-		if (malloc_num_zones_allocated == 0) {
-			new_malloc_num_zones_allocated =
-					vm_page_size / sizeof(malloc_zone_t *);
-		} else if (malloc_num_zones_allocated < (1 << 17)) {
-			// Double up to 128K zones
-			new_malloc_num_zones_allocated = malloc_num_zones_allocated * 2;
-		} else {
-			// Increment in further batches of 128K zones
-			MALLOC_ASSERT(!os_add_overflow(malloc_num_zones_allocated, (1 << 17),
-					&new_malloc_num_zones_allocated));
-		}
-
-		mach_vm_size_t alloc_size = 0;
-		MALLOC_ASSERT(!os_mul_overflow(new_malloc_num_zones_allocated,
-				sizeof(malloc_zone_t *), &alloc_size));
-		alloc_size = round_page(alloc_size);
-
-		mach_vm_address_t vm_addr = (mach_vm_address_t)mvm_allocate_plat(
-				0, (size_t)alloc_size, 0, VM_FLAGS_ANYWHERE,
-				MALLOC_GUARDED_METADATA, VM_MEMORY_MALLOC, NULL);
-		if (vm_addr == 0) {
-			malloc_report(ASL_LEVEL_ERR, "malloc_zone_register allocation failed\n");
+		mach_vm_size_t alloc_size = round_page(malloc_zones_size + vm_page_size);
+		mach_vm_address_t vm_addr;
+		int alloc_flags = VM_FLAGS_ANYWHERE | VM_MAKE_TAG(VM_MEMORY_MALLOC);
+
+		vm_addr = vm_page_size;
+		kern_return_t kr = mach_vm_allocate(mach_task_self(), &vm_addr, alloc_size, alloc_flags);
+		if (kr) {
+			malloc_report(ASL_LEVEL_ERR, "malloc_zone_register allocation failed: %d\n", kr);
 			return;
 		}
 
@@ -1380,26 +723,21 @@
 		 * out of the previous array and into the new zones array */
 		if (malloc_zones) {
 			memcpy(new_zones, malloc_zones, malloc_zones_size);
+			vm_addr = (mach_vm_address_t)malloc_zones;
+			mach_vm_size_t dealloc_size = round_page(malloc_zones_size);
+			mach_vm_deallocate(mach_task_self(), vm_addr, dealloc_size);
 		}
 
 		/* Update the malloc_zones pointer, which we leak if it was previously
 		 * allocated, and the number of zones allocated */
 		protect_size = (size_t)alloc_size;
 		malloc_zones = new_zones;
-		MALLOC_ASSERT(!os_convert_overflow(new_malloc_num_zones_allocated,
-				&malloc_num_zones_allocated));
+		malloc_num_zones_allocated = (int32_t)(alloc_size / sizeof(malloc_zone_t *));
 	} else {
 		/* If we don't need to reallocate zones, we need to briefly change the
 		 * page protection the malloc zones to allow writes */
 		protect_size = malloc_num_zones_allocated * sizeof(malloc_zone_t *);
 		mprotect(malloc_zones, protect_size, PROT_READ | PROT_WRITE);
-	}
-
-	if (make_default) {
-		memmove(&malloc_zones[1], &malloc_zones[0], malloc_num_zones * sizeof(malloc_zone_t *));
-		malloc_zones[0] = zone;
-	} else {
-		malloc_zones[malloc_num_zones] = zone;
 	}
 
 	/* <rdar://problem/12871662> This store-increment needs to be visible in the correct
@@ -1410,37 +748,32 @@
 	 * ensure the proper store-release operation is performed is to use OSAtomic*Barrier
 	 * to update malloc_num_zones.
 	 */
+	malloc_zones[malloc_num_zones] = zone;
 	OSAtomicIncrement32Barrier(&malloc_num_zones);
 
 	/* Finally, now that the zone is registered, disallow write access to the
 	 * malloc_zones array */
 	mprotect(malloc_zones, protect_size, PROT_READ);
-
-	// ASan and others interpose on mprotect() to ensure their zone is always at position 0.
-	if (make_default && malloc_zones[0] != zone) {
-		has_injected_zone0 = true;
-		malloc_slowpath_update();
-	}
-
 	//malloc_report(ASL_LEVEL_INFO, "Registered malloc_zone %p in malloc_zones %p [%u zones, %u bytes]\n", zone, malloc_zones,
 	// malloc_num_zones, protect_size);
 }
 
-// This used to be called lazyily because it is using
-// dyld_process_is_restricted() before dyld_init() has run.
-//
-// However this function is safe to use, we keep this function separate
-// if we ever need to have a 2-stage init in the future.
+// To be used in _malloc_initialize_once() only, call that function instead.
 static void
-_malloc_initialize(const char *apple[], const char *bootargs)
-{
+_malloc_initialize(void *context __unused)
+{
+	MALLOC_LOCK();
+	unsigned n;
+	malloc_zone_t *zone = NULL;
+
+	if (!_malloc_entropy_initialized) {
+		// Lazy initialization may occur before __malloc_init (rdar://27075409)
+		// TODO: make this a fatal error
+		malloc_report(ASL_LEVEL_ERR, "*** malloc was initialized without entropy\n");
+	}
+
 	phys_ncpus = *(uint8_t *)(uintptr_t)_COMM_PAGE_PHYSICAL_CPUS;
 	logical_ncpus = *(uint8_t *)(uintptr_t)_COMM_PAGE_LOGICAL_CPUS;
-#if CONFIG_CLUSTER_AWARE
-	{
-		ncpuclusters = *(uint8_t *)(uintptr_t)_COMM_PAGE_CPU_CLUSTERS;
-	}
-#endif // CONFIG_CLUSTER_AWARE
 
 	if (0 != (logical_ncpus % phys_ncpus)) {
 		MALLOC_REPORT_FATAL_ERROR(logical_ncpus % phys_ncpus,
@@ -1477,300 +810,71 @@
 		max_medium_magazines = max_magazines;
 	}
 
-	// Don't enable for pre-AMP iOS hardware, which we identify as "iOS, plain
-	// arm64"
-#if CONFIG_XZM_CLUSTER_AWARE && \
-		(MALLOC_TARGET_IOS_ONLY || MALLOC_TARGET_DK_IOS) && \
-		defined(__arm64__) && !defined(__arm64e__)
-	if (ncpuclusters == 1) {
-#if CONFIG_FEATUREFLAGS_SIMPLE
-		// Not with the other feature flag checks because ncpuclusters needs to
-		// be initialized first
-		bool secure_allocator_single_cluster = os_feature_enabled_simple(
-				libmalloc, SecureAllocator_SingleCluster, false);
-#else // CONFIG_FEATUREFLAGS_SIMPLE
-		bool secure_allocator_single_cluster = false;
-#endif // CONFIG_FEATUREFLAGS_SIMPLE
-		if (malloc_xzone_enabled && !secure_allocator_single_cluster) {
-			malloc_xzone_enabled = false;
-		}
-	}
+	set_flags_from_environment(); // will only set flags up to two times
+	n = malloc_num_zones;
+
+#if CONFIG_NANOZONE
+	nano_common_configure();
+	
+	malloc_zone_t *helper_zone = create_scalable_zone(0, malloc_debug_flags);
+
+	if (_malloc_engaged_nano == NANO_V2) {
+		zone = nanov2_create_zone(helper_zone, malloc_debug_flags);
+	} else if (_malloc_engaged_nano == NANO_V1) {
+		zone = nano_create_zone(helper_zone, malloc_debug_flags);
+	}
+
+	if (zone) {
+		malloc_zone_register_while_locked(zone);
+		malloc_zone_register_while_locked(helper_zone);
+
+		// Must call malloc_set_zone_name() *after* helper and nano are hooked together.
+		malloc_set_zone_name(zone, DEFAULT_MALLOC_ZONE_STRING);
+		malloc_set_zone_name(helper_zone, MALLOC_HELPER_ZONE_STRING);
+	} else {
+		zone = helper_zone;
+		malloc_zone_register_while_locked(zone);
+		malloc_set_zone_name(zone, DEFAULT_MALLOC_ZONE_STRING);
+	}
+#else
+	zone = create_scalable_zone(0, malloc_debug_flags);
+	malloc_zone_register_while_locked(zone);
+	malloc_set_zone_name(zone, DEFAULT_MALLOC_ZONE_STRING);
 #endif
 
-	_malloc_detect_interposition();
-
-#if CONFIG_MTE
-	malloc_has_sec_transition = _malloc_check_has_sec_transition(apple);
-	// If the process has been spawned by setting has_sec_transition=1,
-	// enable the usage of xzone and the nano override by default.
-	// Note that we still allow overriding this behaviour through
-	// environment variables (whose values are loaded afterwards).
-	if (malloc_has_sec_transition) {
-		malloc_xzone_enabled = true;
-		malloc_xzone_nano_override = MALLOC_XZONE_OVERRIDE_ENABLED;
-		malloc_sec_transition_early_malloc_support = true;
-		malloc_sec_transition_policy = _malloc_get_sec_transition_policy(apple);
-	}
-#endif
-
-	set_flags_from_environment();
-	
-	// Add-in mask bits that can be set via env var MallocEnableMSLAtLimitWarning, for libdispatch to setup the desired handlers
-	malloc_memorypressure_mask_default_4libdispatch |= malloc_memorystatus_mask_resource_exception_handling;
-	malloc_memorypressure_mask_msl_4libdispatch |= malloc_memorystatus_mask_resource_exception_handling;
-
-	if (malloc_report_config) {
-		malloc_report(ASL_LEVEL_INFO, "Internal Security Policy: %d\n",
-				malloc_internal_security_policy);
-	}
-
-
-#if CONFIG_SANITIZER
-	malloc_sanitizer_enabled = sanitizer_should_enable();
-#endif
-	
-	// TODO: envp should be passed down from Libsystem
-	const char **envp = (const char **)*_NSGetEnviron();
-
-#if CONFIG_NANOZONE
-	// Disable nano when:
-	// - sanitizer is enabled, to avoid speculative out-of-bounds
-	//   use-after-free reads that nano/nanov2 performs, OR
-	// - MallocScribble is enabled, which nanov2 does not implement
-	// - MallocCheckZeroOnFreeCorruption sampling is enabled, which nanov2 does
-	//   not implement
-	if (!malloc_sanitizer_enabled &&
-			!(malloc_debug_flags & MALLOC_DO_SCRIBBLE) &&
-			!malloc_zero_on_free_sample_period) {
-		nano_common_init(envp, apple, bootargs);
-	}
-#else // CONFIG_NANOZONE
-	(void)envp;
-#endif // CONFIG_NANOZONE
-
-	bool nano_on_xzone = false;
-
-#if CONFIG_XZONE_MALLOC
-#if CONFIG_NANOZONE
-	bool nano_xzone_enabled = false;
-#if CONFIG_FEATUREFLAGS_SIMPLE
-	nano_xzone_enabled = os_feature_enabled_simple(libmalloc,
-			SecureAllocator_Nano, MALLOC_XZONE_NANO_ENABLED_DEFAULT);
-#elif MALLOC_TARGET_DK_OSX
-	nano_xzone_enabled = true;
-#endif // CONFIG_FEATUREFLAGS_SIMPLE
-
-#if CONFIG_MALLOC_PROCESS_IDENTITY
-	if (malloc_process_is_security_critical(malloc_process_identity)) {
-		// This is load-bearing for MTLCompilerService
-		nano_xzone_enabled = true;
-	}
-#endif // CONFIG_MALLOC_PROCESS_IDENTITY
-
-	switch (malloc_xzone_nano_override) {
-	case MALLOC_XZONE_OVERRIDE_DISABLED:
-		nano_xzone_enabled = false;
-		break;
-	case MALLOC_XZONE_OVERRIDE_ENABLED:
-		nano_xzone_enabled = true;
-		break;
-	default:
-		break;
-	}
-
-	// If we're forcing nano-on-xzone via the environment, take that even if
-	// we'd otherwise take the nano config of xzone
-	if (malloc_nano_on_xzone_override == MALLOC_XZONE_OVERRIDE_ENABLED) {
-		nano_xzone_enabled = false;
-	}
-
-	if (malloc_xzone_enabled && _malloc_engaged_nano == NANO_V2 &&
-			!nano_xzone_enabled) {
-#if TARGET_OS_SIMULATOR
-		// Note: simulator processes get nano by default because
-		// NANOV2_DEFAULT_MODE is conditioned on MALLOC_TARGET_IOS, which
-		// excludes the simulator.  So, simulator processes will not get xzone
-		// malloc until we either adjust this policy or enable it by default
-		// under nano.
-		malloc_xzone_enabled = false;
-#else // TARGET_OS_SIMULATOR
-#if CONFIG_FEATUREFLAGS_SIMPLE
-		nano_on_xzone = os_feature_enabled_simple(libmalloc,
-				SecureAllocator_NanoOnXzone, false);
-#endif // CONFIG_FEATUREFLAGS_SIMPLE
-
-		switch (malloc_nano_on_xzone_override) {
-		case MALLOC_XZONE_OVERRIDE_DISABLED:
-			nano_on_xzone = false;
-			break;
-		case MALLOC_XZONE_OVERRIDE_ENABLED:
-			nano_on_xzone = true;
-			break;
-		default:
-			break;
-		}
-
-		if (malloc_nano_on_xzone != nano_on_xzone) {
-			malloc_nano_on_xzone = nano_on_xzone;
-		}
-
-		if (!nano_on_xzone) {
-			malloc_xzone_enabled = false;
-		}
-#endif // TARGET_OS_SIMULATOR
-	}
-#endif // CONFIG_NANOZONE
-
-	if (malloc_xzone_enabled) {
-		mvm_guarded_range_init();
-
-		if (malloc_report_config && malloc_internal_security_policy) {
-			malloc_report(ASL_LEVEL_INFO,
-					"Guarded Range Config (base/size/carveout):"
-					" 0x%lx / 0x%lx / 0x%lx\n",
-					(unsigned long)malloc_guarded_range_config.base_address,
-					(unsigned long)malloc_guarded_range_config.size,
-					(unsigned long)malloc_guarded_range_config.carveout_address);
-		}
-
-		initial_xzone_zone = xzm_main_malloc_zone_create(malloc_debug_flags,
-				envp, apple, bootargs);
-
-		// Note: although it would be ideal if we could give this zone a unique
-		// name that draws attention to the fact that it will not behave like a
-		// nano or scalable zone, a lot of code looks specifically for
-		// "DefaultMallocZone" when looking for/at the default zone, so that's
-		// the name we'll need to continue to take.
-		malloc_set_zone_name(initial_xzone_zone, DEFAULT_MALLOC_ZONE_STRING);
-		malloc_zone_register_while_locked(initial_xzone_zone, /*make_default=*/true);
-	}
-#endif // CONFIG_XZONE_MALLOC
-
-	if (!initial_xzone_zone || nano_on_xzone) {
-		if (!initial_xzone_zone) {
-			initial_scalable_zone = create_scalable_zone(0, malloc_debug_flags);
-			malloc_set_zone_name(initial_scalable_zone, DEFAULT_MALLOC_ZONE_STRING);
-			malloc_zone_register_while_locked(initial_scalable_zone, /*make_default=*/true);
-		}
-
-#if CONFIG_NANOZONE
-		nano_common_configure();
-
-		malloc_zone_t *helper_zone = initial_xzone_zone ?: initial_scalable_zone;
-
-		if (_malloc_engaged_nano == NANO_V2) {
-			if (malloc_report_config) {
-				bool nano_on_xzone_enabled = (helper_zone == initial_xzone_zone);
-				malloc_report(ASL_LEVEL_INFO, "NanoV2 Config:\n"
-						"\tNano On Xzone: %d\n",
-						nano_on_xzone_enabled);
-			}
-			initial_nano_zone = nanov2_create_zone(helper_zone, malloc_debug_flags);
-		}
-
-		if (initial_nano_zone) {
-			malloc_set_zone_name(initial_nano_zone, DEFAULT_MALLOC_ZONE_STRING);
-			malloc_set_zone_name(helper_zone, MALLOC_HELPER_ZONE_STRING);
-			malloc_zone_register_while_locked(initial_nano_zone, /*make_default=*/true);
-		}
-#endif
-	}
-
-#if CONFIG_SANITIZER
-	if (malloc_sanitizer_enabled) {
-		malloc_zone_t *wrapped_zone = malloc_zones[0];
-		malloc_zone_t *sanitizer_zone = sanitizer_create_zone(wrapped_zone);
-		malloc_zone_register_while_locked(sanitizer_zone, /*make_default=*/true);
-	}
-#endif
-
-	// Initialize slowpath check after we've registered zones so that
-	// malloc_num_zones check is meaningful
-	malloc_slowpath_update();
-
-	initial_num_zones = malloc_num_zones;
-
-#if CONFIG_MAGAZINE_DEFERRED_RECLAIM
-	mach_vm_reclaim_error_t vmdr_kr = VM_RECLAIM_SUCCESS;
-	if (large_cache_enabled) {
-		const bool xzone_deferred_reclaim = initial_xzone_zone;
-		if (xzone_deferred_reclaim) {
-			// xzone_malloc will own the deferred_reclaim buffer
-			large_cache_enabled = false;
-		} else {
-			vmdr_kr = mvm_deferred_reclaim_init();
-			if (vmdr_kr != VM_RECLAIM_SUCCESS) {
-				large_cache_enabled = false;
-				malloc_report(ASL_LEVEL_ERR, "Unable to set up "
-						"reclaim buffer, disabling "
-						"large cache [%d] %s\n",
-						err_get_code(vmdr_kr),
-						mach_error_string(vmdr_kr));
-			}
-		}
-	}
-#endif // CONFIG_MAGAZINE_DEFERRED_RECLAIM
-
-	if (malloc_report_config && initial_scalable_zone) {
-		bool scribble = !!(malloc_debug_flags & MALLOC_DO_SCRIBBLE);
-		malloc_report(ASL_LEVEL_INFO, "Magazine Config:\n"
-				"\tMax Magazines: %d\n"
-				"\tMedium Enabled: %d\n"
-				"\tAggressive Madvise: %d\n"
-#if CONFIG_MAGAZINE_DEFERRED_RECLAIM
-				"\tLarge Cache: %d%s\n"
-#endif // CONFIG_MAGAZINE_DEFERRED_RECLAIM
-				"\tScribble: %d\n",
-				max_magazines, magazine_medium_enabled,
-				aggressive_madvise_enabled,
-#if CONFIG_MAGAZINE_DEFERRED_RECLAIM
-				vmdr_kr ?: large_cache_enabled, vmdr_kr ? " (ERROR)" : "",
-#endif // CONFIG_MAGAZINE_DEFERRED_RECLAIM
-				scribble);
-	}
-
-#if CONFIG_MEDIUM_ALLOCATOR
-	uint64_t memsize = platform_hw_memsize();
-	if (memsize >= 8 * magazine_medium_madvise_dram_scale_divisor) {
-		magazine_medium_madvise_window_scale_factor = 8;
-	} else if (memsize >= 4 * magazine_medium_madvise_dram_scale_divisor) {
-		magazine_medium_madvise_window_scale_factor = 4;
-	} else if (memsize >= 2 * magazine_medium_madvise_dram_scale_divisor) {
-		magazine_medium_madvise_window_scale_factor = 2;
-	} else {
-		magazine_medium_madvise_window_scale_factor = 1;
-	}
-#endif /* CONFIG_MEDIUM_ALLOCATOR */
+	initial_default_zone = zone;
+
+	if (n != 0) { // make the default first, for efficiency
+		unsigned protect_size = malloc_num_zones_allocated * sizeof(malloc_zone_t *);
+		malloc_zone_t *hold = malloc_zones[0];
+
+		if (hold->zone_name && strcmp(hold->zone_name, DEFAULT_MALLOC_ZONE_STRING) == 0) {
+			malloc_set_zone_name(hold, NULL);
+		}
+
+		mprotect(malloc_zones, protect_size, PROT_READ | PROT_WRITE);
+		malloc_zones[0] = malloc_zones[n];
+		malloc_zones[n] = hold;
+		mprotect(malloc_zones, protect_size, PROT_READ);
+	}
 
 	// malloc_report(ASL_LEVEL_INFO, "%d registered zones\n", malloc_num_zones);
 	// malloc_report(ASL_LEVEL_INFO, "malloc_zones is at %p; malloc_num_zones is at %p\n", (unsigned)&malloc_zones,
 	// (unsigned)&malloc_num_zones);
-}
-
-static bool
-enable_pgm(unsigned flags)
-{
-	bool other_debug_tool = has_injected_zone0 || malloc_sanitizer_enabled;
-	// To avoid allocations in the lite helper zone that don't have msl data at
-	// the end of the allocation, don't enable PGM on the lite helper zone
-	bool zone_is_msl = flags & MALLOC_MSL_LITE_WRAPPED_ZONE_FLAGS;
-	return !other_debug_tool && !zone_is_msl && pgm_should_enable();
-}
-
-static void
-register_pgm_zone(bool internal_diagnostics)
-{
-	pgm_init_config(internal_diagnostics);
-	if (enable_pgm(0)) {
-		malloc_zone_t *wrapped_zone = malloc_zones[0];
-		malloc_zone_t *pgm_zone = pgm_create_zone(wrapped_zone);
-		malloc_zone_register_while_locked(pgm_zone, /*make_default=*/true);
-	}
+	MALLOC_UNLOCK();
+}
+
+MALLOC_ALWAYS_INLINE
+static inline void
+_malloc_initialize_once(void)
+{
+	os_once(&_malloc_initialize_pred, NULL, _malloc_initialize);
 }
 
 static inline malloc_zone_t *
 inline_malloc_default_zone(void)
 {
+	_malloc_initialize_once();
 	// malloc_report(ASL_LEVEL_INFO, "In inline_malloc_default_zone with %d %d\n", malloc_num_zones, malloc_has_debug_zone);
 	return malloc_zones[0];
 }
@@ -1779,6 +883,41 @@
 malloc_default_zone(void)
 {
 	return default_zone;
+}
+
+static inline malloc_zone_t *inline_malloc_default_scalable_zone(void) __attribute__((always_inline));
+static inline malloc_zone_t *
+inline_malloc_default_scalable_zone(void)
+{
+	unsigned index;
+
+	_malloc_initialize_once();
+	// malloc_report(ASL_LEVEL_INFO, "In inline_malloc_default_scalable_zone with %d %d\n", malloc_num_zones,
+	// malloc_has_debug_zone);
+
+	MALLOC_LOCK();
+#if CONFIG_NANOZONE
+	for (index = 0; index < malloc_num_zones; ++index) {
+		malloc_zone_t *z = malloc_zones[index];
+
+		if (z->zone_name && strcmp(z->zone_name, MALLOC_HELPER_ZONE_STRING) == 0) {
+			MALLOC_UNLOCK();
+			return z;
+		}
+	}
+#endif
+	for (index = 0; index < malloc_num_zones; ++index) {
+		malloc_zone_t *z = malloc_zones[index];
+
+		if (z->zone_name && strcmp(z->zone_name, DEFAULT_MALLOC_ZONE_STRING) == 0) {
+			MALLOC_UNLOCK();
+			return z;
+		}
+	}
+	MALLOC_UNLOCK();
+
+	malloc_report(ASL_LEVEL_ERR, "*** malloc_default_scalable_zone() failed to find 'DefaultMallocZone'\n");
+	return NULL; // FIXME: abort() instead?
 }
 
 static void *
@@ -1825,16 +964,30 @@
 malloc_engaged_nano(void)
 {
 #if CONFIG_NANOZONE
-	return (initial_nano_zone || initial_xzone_zone) ? _malloc_engaged_nano : 0;
+	return _malloc_engaged_nano;
 #else
 	return 0;
 #endif
 }
 
-int
-malloc_engaged_secure_allocator(void)
-{
-	return !!initial_xzone_zone;
+malloc_zone_t *
+malloc_default_purgeable_zone(void)
+{
+	static malloc_zone_t *dpz;
+
+	if (!dpz) {
+		//
+		// PR_7288598: Must pass a *scalable* zone (szone) as the helper for create_purgeable_zone().
+		// Take care that the zone so obtained is not subject to interposing.
+		//
+		malloc_zone_t *tmp = create_purgeable_zone(0, inline_malloc_default_scalable_zone(), malloc_debug_flags);
+		malloc_zone_register(tmp);
+		malloc_set_zone_name(tmp, DEFAULT_PUREGEABLE_ZONE_STRING);
+		if (!OSAtomicCompareAndSwapPtrBarrier(NULL, tmp, (void**)&dpz)) {
+			malloc_destroy_zone(tmp);
+		}
+	}
+	return dpz;
 }
 
 static void
@@ -1845,7 +998,7 @@
 	const char **p;
 	const char *c;
 
-#if defined(__LP64__)
+#if __LP64__
 	malloc_debug_flags = MALLOC_ABORT_ON_CORRUPTION; // Set always on 64-bit processes
 #else
 	int libSystemVersion = NSVersionOfLinkTimeLibrary("System");
@@ -1855,20 +1008,6 @@
 		malloc_debug_flags = MALLOC_ABORT_ON_CORRUPTION;
 	}
 #endif
-
-#if TARGET_OS_OSX
-	// rdar://99288027
-	if (dyld_get_active_platform() == PLATFORM_MACOS &&
-			!dyld_program_sdk_at_least(dyld_platform_version_macOS_13_0)) {
-		if (malloc_zero_policy == MALLOC_ZERO_ON_FREE) {
-			malloc_zero_policy = MALLOC_ZERO_ON_ALLOC;
-			malloc_xzone_enabled = false;
-		}
-	}
-
-#else // TARGET_OS_OSX
-#endif // TARGET_OS_OSX
-
 	/*
 	 * Given that all environment variables start with "Malloc" we optimize by scanning quickly
 	 * first the environment, therefore avoiding repeated calls to getenv().
@@ -1900,32 +1039,19 @@
 		return;
 	}
 
-	flag = getenv("MallocGuardEdges");
-	if (flag) {
-		if (!strcmp(flag, "all")) {
-			// "MallocGuardEdges=all" adds guard page(s) for every region.
-			// Do not do this on 32-bit platforms because there is insufficient
-			// address space. These pages are always protected.
-#if MALLOC_TARGET_64BIT
-			malloc_debug_flags |= MALLOC_GUARD_ALL | MALLOC_ADD_GUARD_PAGE_FLAGS;
-			malloc_debug_flags &= ~(MALLOC_DONT_PROTECT_PRELUDE|MALLOC_DONT_PROTECT_POSTLUDE);
-			malloc_report(ASL_LEVEL_INFO, "adding guard pages to all regions\n");
-#endif // MALLOC_TARGET_64BIT
-		} else {
-			malloc_debug_flags |= MALLOC_ADD_GUARD_PAGE_FLAGS;
-			malloc_debug_flags &= ~MALLOC_GUARD_ALL;
-			malloc_report(ASL_LEVEL_INFO, "adding guard pages for large allocator blocks\n");
-			if (getenv("MallocDoNotProtectPrelude")) {
-				malloc_debug_flags |= MALLOC_DONT_PROTECT_PRELUDE;
-				malloc_report(ASL_LEVEL_INFO, "... but not protecting prelude guard page\n");
-			}
-			if (getenv("MallocDoNotProtectPostlude")) {
-				malloc_debug_flags |= MALLOC_DONT_PROTECT_POSTLUDE;
-				malloc_report(ASL_LEVEL_INFO, "... but not protecting postlude guard page\n");
-			}
-		}
-	}
-
+	if (getenv("MallocGuardEdges")) {
+		malloc_debug_flags |= MALLOC_ADD_GUARD_PAGES;
+		malloc_report(ASL_LEVEL_INFO, "protecting edges\n");
+		if (getenv("MallocDoNotProtectPrelude")) {
+			malloc_debug_flags |= MALLOC_DONT_PROTECT_PRELUDE;
+			malloc_report(ASL_LEVEL_INFO, "... but not protecting prelude guard page\n");
+		}
+		if (getenv("MallocDoNotProtectPostlude")) {
+			malloc_debug_flags |= MALLOC_DONT_PROTECT_POSTLUDE;
+			malloc_report(ASL_LEVEL_INFO, "... but not protecting postlude guard page\n");
+		}
+	}
+	
 	if (getenv("MallocScribble")) {
 		malloc_debug_flags |= MALLOC_DO_SCRIBBLE;
 		malloc_report(ASL_LEVEL_INFO, "enabling scribbling to detect mods to free blocks\n");
@@ -1937,14 +1063,8 @@
 	if (getenv("MallocTracing")) {
 		malloc_tracing_enabled = true;
 	}
-	if (getenv("MallocSimpleStackLogging")) {
-		malloc_simple_stack_logging = true;
-	}
-	if (getenv("MallocReportConfig")) {
-		malloc_report_config = true;
-	}
-
-#if defined(__LP64__)
+
+#if __LP64__
 /* initialization above forces MALLOC_ABORT_ON_CORRUPTION of 64-bit processes */
 #else
 	flag = getenv("MallocCorruptionAbort");
@@ -2002,19 +1122,9 @@
 	}
 #endif // RDAR_48993662
 	if (flag) {
-
-		int value = (int)strtol(flag, NULL, 0);
+		int value = (unsigned)strtol(flag, NULL, 0);
 		if (value == 0) {
 			malloc_report(ASL_LEVEL_INFO, "Maximum magazines defaulted to %d\n", max_magazines);
-#if CONFIG_MAGAZINE_PER_CLUSTER
-		} else if (value == UINT16_MAX) {
-			{
-				max_magazines = ncpuclusters;
-				malloc_report(ASL_LEVEL_INFO,
-						"Maximum magazines limited to ncpuclusters (%d)\n",
-						max_magazines);
-			}
-#endif // CONFIG_MAGAZINE_PER_CLUSTER
 		} else if (value < 0) {
 			malloc_report(ASL_LEVEL_ERR, "Maximum magazines must be positive - ignored.\n");
 		} else if (value > logical_ncpus) {
@@ -2039,43 +1149,6 @@
 		}
 	}
 
-	flag = getenv("MallocLargeDisableASLR");
-	if (flag) {
-		uint64_t value = (uint64_t)strtoull(flag, NULL, 0);
-		if (value == 0) {
-			malloc_report(ASL_LEVEL_INFO, "Enabling ASLR slide on large allocations\n");
-			malloc_debug_flags &= ~DISABLE_LARGE_ASLR;
-		} else if (value != 0) {
-			malloc_report(ASL_LEVEL_INFO, "Disabling ASLR slide on large allocations\n");
-			malloc_debug_flags |= DISABLE_LARGE_ASLR;
-		}
-	}
-
-#if CONFIG_AGGRESSIVE_MADVISE || CONFIG_LARGE_CACHE
-	// convenience flag to configure policies usually associated with memory-constrained platforms (iOS)
-	// that trade some amount of time efficiency for space efficiency
-	flag = getenv("MallocSpaceEfficient");
-	if (flag) {
-		const char *endp;
-		long value = malloc_common_convert_to_long(flag, &endp);
-		if (!*endp && endp != flag && (value == 0 || value == 1)) {
-#if CONFIG_AGGRESSIVE_MADVISE
-			aggressive_madvise_enabled = (value == 1);
-#endif // CONFIG_AGGRESSIVE_MADVISE
-#if CONFIG_LARGE_CACHE
-			// Disable the large cache in space efficient mode
-			if (value != 0){
-				large_cache_enabled = 0;
-			}
-#endif // CONFIG_LARGE_CACHE
-			malloc_space_efficient_enabled = (value == 1);
-			// consider disabling medium magazine if aggressive madvise is not sufficient
-		} else {
-			malloc_report(ASL_LEVEL_ERR, "MallocSpaceEfficient must be 0 or 1.\n");
-		}
-	}
-#endif // CONFIG_AGGRESSIVE_MADVISE || CONFIG_LARGE_CACHE
-
 #if CONFIG_MEDIUM_ALLOCATOR
 	flag = getenv("MallocMediumZone");
 	if (flag) {
@@ -2098,23 +1171,6 @@
 			magazine_medium_active_threshold = value;
 			malloc_report(ASL_LEVEL_INFO, "Medium activation threshold set to %lly\n", magazine_medium_active_threshold);
 		}
-	}
-
-	flag = getenv("MallocMediumSpaceEfficient");
-	if (flag) {
-		uint64_t value = (uint64_t)strtoull(flag, NULL, 0);
-		if (value == 0) {
-			malloc_medium_space_efficient_enabled = false;
-		} else if (value == 1) {
-			malloc_medium_space_efficient_enabled = true;
-		}
-	}
-
-	if (malloc_medium_space_efficient_enabled && malloc_space_efficient_enabled) {
-		// Bring down MallocMaxMediumMagazines to only a single magazine in
-		// space-efficent processes but do this before the envvar so that it
-		// can still be overridden at the command line.
-		max_medium_magazines = 1;
 	}
 
 	flag = getenv("MallocMaxMediumMagazines");
@@ -2139,32 +1195,6 @@
 	}
 #endif // CONFIG_MEDIUM_ALLOCATOR
 
-#if CONFIG_AGGRESSIVE_MADVISE
-	flag = getenv("MallocAggressiveMadvise");
-	if (flag) {
-		const char *endp;
-		long value = malloc_common_convert_to_long(flag, &endp);
-		if (!*endp && endp != flag && (value == 0 || value == 1)) {
-			aggressive_madvise_enabled = (value == 1);
-		} else {
-			malloc_report(ASL_LEVEL_ERR, "MallocAggressiveMadvise must be 0 or 1.\n");
-		}
-	}
-#endif // CONFIG_AGGRESSIVE_MADVISE
-
-#if CONFIG_LARGE_CACHE
-	flag = getenv("MallocLargeCache");
-	if (flag) {
-		const char *endp;
-		long value = malloc_common_convert_to_long(flag, &endp);
-		if (!*endp && endp != flag && (value == 0 || value == 1)) {
-			large_cache_enabled = (value == 1);
-		} else {
-			malloc_report(ASL_LEVEL_ERR, "MallocLargeCache must be 0 or 1.\n");
-		}
-	}
-#endif // CONFIG_LARGE_CACHE
-
 #if CONFIG_RECIRC_DEPOT
 	flag = getenv("MallocRecircRetainedRegions");
 	if (flag) {
@@ -2176,123 +1206,6 @@
 		}
 	}
 #endif // CONFIG_RECIRC_DEPOT
-
-	flag = getenv("MallocZeroOnFree");
-	if (flag) {
-		const char *endp;
-		long value = malloc_common_convert_to_long(flag, &endp);
-		if (!*endp && endp != flag && (value == 0 || value == 1)) {
-			malloc_zero_policy = value ? MALLOC_ZERO_ON_FREE : MALLOC_ZERO_NONE;
-		} else {
-			malloc_report(ASL_LEVEL_ERR, "MallocZeroOnFree must be 0 or 1.\n");
-		}
-	}
-
-	flag = getenv("MallocZeroOnAlloc");
-	if (flag) {
-		const char *endp;
-		long value = malloc_common_convert_to_long(flag, &endp);
-		if (!*endp && endp != flag && (value == 0 || value == 1)) {
-			malloc_zero_policy = value ? MALLOC_ZERO_ON_ALLOC : MALLOC_ZERO_NONE;
-		} else {
-			malloc_report(ASL_LEVEL_ERR, "MallocZeroOnAlloc must be 0 or 1.\n");
-		}
-	}
-
-	flag = getenv("MallocCheckZeroOnFreeCorruption");
-	if (flag) {
-		int value = (int)strtol(flag, NULL, 0);
-		if (value > 0) {
-			malloc_zero_on_free_sample_period = value;
-		} else {
-			malloc_report(ASL_LEVEL_ERR,
-					"malloc_zero_on_free_sample_period must be positive - ignored.\n");
-		}
-	}
-
-	flag = getenv("MallocSecureAllocator");
-	if (flag && malloc_internal_security_policy) {
-		const char *endp;
-		long value = malloc_common_convert_to_long(flag, &endp);
-		if (!*endp && endp != flag && (value == 0 || value == 1)) {
-			malloc_xzone_enabled = value;
-		} else {
-			malloc_report(ASL_LEVEL_ERR, "MallocSecureAllocator must be 0 or 1.\n");
-		}
-	}
-
-	flag = getenv("MallocSecureAllocatorNano");
-	if (flag) {
-		const char *endp;
-		long value = malloc_common_convert_to_long(flag, &endp);
-		if (!*endp && endp != flag && (value == 0 || value == 1)) {
-			malloc_xzone_nano_override = value ? MALLOC_XZONE_OVERRIDE_ENABLED :
-					MALLOC_XZONE_OVERRIDE_DISABLED;
-		} else {
-			malloc_report(ASL_LEVEL_ERR, "MallocSecureAllocatorNano must be 0 or 1.\n");
-		}
-	}
-
-	flag = getenv("MallocNanoOnXzone");
-	if (flag) {
-		const char *endp;
-		long value = malloc_common_convert_to_long(flag, &endp);
-		if (!*endp && endp != flag && (value == 0 || value == 1)) {
-			malloc_nano_on_xzone_override = value ? MALLOC_XZONE_OVERRIDE_ENABLED :
-					MALLOC_XZONE_OVERRIDE_DISABLED;
-		} else {
-			malloc_report(ASL_LEVEL_ERR, "MallocNanoOnXzone must be 0 or 1.\n");
-		}
-	}
-
-#if CONFIG_XZONE_MALLOC
-	flag = getenv("MallocSecureAllocatorCreateMzones");
-	if (flag && malloc_internal_security_policy) {
-		const char *endp;
-		long value = malloc_common_convert_to_long(flag, &endp);
-		if (!*endp && endp != flag && (value == 0 || value == 1)) {
-			xzm_create_mzones = value;
-		} else {
-			malloc_report(ASL_LEVEL_ERR,
-					"MallocSecureAllocatorCreateMzones must be 0 or 1.\n");
-		}
-	}
-	flag = getenv("MallocSecureAllocatorPurgeableZone");
-	if (flag && malloc_internal_security_policy) {
-		const char *endp;
-		long value = malloc_common_convert_to_long(flag, &endp);
-		if (!*endp && endp != flag && (value == 0 || value == 1)) {
-			purgeable_zone_use_xzm = value;
-		} else {
-			malloc_report(ASL_LEVEL_ERR,
-					"MallocSecureAllocatorPurgeableZone must be 0 or 1.\n");
-		}
-	}
-#endif // CONFIG_XZONE_MALLOC
-
-#if CONFIG_MTE
-	flag = getenv("MallocEarlyMallocSecTransitionSupport");
-	if (flag) {
-		const char *endp;
-		long value = malloc_common_convert_to_long(flag, &endp);
-		if (!*endp && endp != flag && (value == 0 || value == 1)) {
-			malloc_sec_transition_early_malloc_support = value;
-		} else {
-			malloc_report(ASL_LEVEL_ERR,
-					"MallocEarlyMallocSecTransitionSupport must be 0 or 1.\n");
-		}
-	}
-#endif // CONFIG_MTE
-		
-	flag = getenv("MallocEnableMSLAtLimitWarning");
-	if (flag) {
-		const char *endp;
-		long value = malloc_common_convert_to_long(flag, &endp);
-		if (!*endp && endp != flag && value == 1) {
-			malloc_memorystatus_mask_resource_exception_handling |= MALLOC_MEMORYSTATUS_MASK_RESOURCE_EXCEPTION_HANDLING;
-		}
-	}
-
 	if (getenv("MallocHelp")) {
 		malloc_report(ASL_LEVEL_INFO,
 				"environment variables that can be set for debug:\n"
@@ -2313,74 +1226,21 @@
 				"  MallocCorruptionAbort is always set on 64-bit processes\n"
 				"- MallocErrorAbort to abort on any malloc error, including out of memory\n"\
 				"- MallocTracing to emit kdebug trace points on malloc entry points\n"\
-				"- MallocZeroOnFree to enable or disable zero-on-free behavior (for debugging only)\n"\
-				"- MallocCheckZeroOnFreeCorruption to enable zero-on-free corruption detection\n"\
 				"- MallocHelp - this help!\n");
 	}
 }
-
-#if CONFIG_MTE
-static bool
-_malloc_check_has_sec_transition(const char *apple[])
-{
-	const char *flag = _simple_getenv(apple, "has_sec_transition");
-	if (flag) {
-		const char *endp;
-		long value = malloc_common_convert_to_long(flag, &endp);
-		if (!*endp && endp != flag && (value == 0 || value == 1)) {
-			return (bool)value;
-		}
-	}
-	return false;
-}
-
-static uint32_t
-_malloc_get_sec_transition_policy(const char *apple[])
-{
-	const char *flag = _simple_getenv(apple, "sec_transition_policy");
-	uint32_t policy = 0;
-	if (flag) {
-		char *endp;
-		unsigned long value = strtoul(flag, &endp, 0);
-		if (!*endp && endp != flag) {
-			policy = (uint32_t)value;
-		}
-	}
-	return policy;
-}
-
-#endif // CONFIG_MTE
 
 malloc_zone_t *
 malloc_create_zone(vm_size_t start_size, unsigned flags)
 {
-	malloc_zone_t *zone = NULL;
+	malloc_zone_t *zone;
 
 	/* start_size doesn't actually appear to be used, but we test anyway. */
-	if (start_size > malloc_absolute_max_size) {
+	if (start_size > MALLOC_ABSOLUTE_MAX_SIZE) {
 		return NULL;
 	}
-
-#if CONFIG_XZONE_MALLOC
-	if (initial_xzone_zone && xzm_create_mzones) {
-		zone = xzm_malloc_zone_create(flags | malloc_debug_flags,
-				(xzm_main_malloc_zone_t)initial_xzone_zone);
-	}
-#endif // CONFIG_XZONE_MALLOC
-
-	if (!zone) {
-		zone = create_scalable_zone(start_size, flags | malloc_debug_flags);
-	}
-
-	if (enable_pgm(flags)) {
-		malloc_zone_t *pgm_zone = pgm_create_zone(zone);
-		MALLOC_LOCK();
-		malloc_zone_register_while_locked(pgm_zone, false);
-		malloc_zone_register_while_locked(zone, false);
-		MALLOC_UNLOCK();
-		return pgm_zone;
-	}
-
+	_malloc_initialize_once();
+	zone = create_scalable_zone(start_size, flags | malloc_debug_flags);
 	malloc_zone_register(zone);
 	return zone;
 }
@@ -2393,10 +1253,13 @@
 malloc_create_legacy_default_zone(void)
 {
 	malloc_zone_t *zone;
-
+	int i;
+
+	_malloc_initialize_once();
 	zone = create_legacy_scalable_zone(0, malloc_debug_flags);
 
 	MALLOC_LOCK();
+	malloc_zone_register_while_locked(zone);
 
 	//
 	// Establish the legacy scalable zone just created as the default zone.
@@ -2407,7 +1270,16 @@
 	}
 	malloc_set_zone_name(zone, DEFAULT_MALLOC_ZONE_STRING);
 
-	malloc_zone_register_while_locked(zone, /*make_default=*/true);
+	unsigned protect_size = malloc_num_zones_allocated * sizeof(malloc_zone_t *);
+	mprotect(malloc_zones, protect_size, PROT_READ | PROT_WRITE);
+
+	// assert(zone == malloc_zones[malloc_num_zones - 1];
+	for (i = malloc_num_zones - 1; i > 0; --i) {
+		malloc_zones[i] = malloc_zones[i - 1];
+	}
+	malloc_zones[0] = zone;
+
+	mprotect(malloc_zones, protect_size, PROT_READ);
 	MALLOC_UNLOCK();
 }
 
@@ -2492,13 +1364,9 @@
 
 /*********	Block creation and manipulation	************/
 
-__attribute__((cold, noinline))
 static void
 internal_check(void)
 {
-	if (malloc_check_counter++ < malloc_check_start) {
-		return;
-	}
 	if (malloc_zone_check(NULL)) {
 		if (!frames) {
 			vm_allocate(mach_task_self(), (void *)&frames, vm_page_size, 1);
@@ -2508,314 +1376,106 @@
 	malloc_check_start += malloc_check_each;
 }
 
-MALLOC_NOINLINE
-static void *
-_malloc_zone_malloc_instrumented_or_legacy(malloc_zone_t *zone, size_t size,
-		malloc_zone_options_t mzo)
-{
-	uint64_t type_id = malloc_get_tsd_type_id();
-#if MALLOC_TARGET_64BIT
-	bool clear_type = false;
-	if (!type_id) {
-		malloc_type_descriptor_t fallback =
-				malloc_callsite_fallback_type_descriptor();
-		malloc_set_tsd_type_descriptor(fallback);
-		type_id = fallback.type_id;
-		clear_type = true;
-	}
-#endif // MALLOC_TARGET_64BIT
-	MALLOC_TRACE(TRACE_malloc | DBG_FUNC_START, (uintptr_t)zone, size, type_id,
-			0);
-
-	void *ptr = NULL;
-
-	if (malloc_check_start) {
-		internal_check();
-	}
-	if (size > malloc_absolute_max_size) {
-		goto out;
-	}
-
-	ptr = zone->malloc(zone, size);
-
-	if (os_unlikely(malloc_logger)) {
-		malloc_logger(MALLOC_LOG_TYPE_ALLOCATE | MALLOC_LOG_TYPE_HAS_ZONE,
-				(uintptr_t)zone, (uintptr_t)size, 0, (uintptr_t)ptr, 0);
-	}
-
-	if (os_unlikely(malloc_simple_stack_logging)) {
-		malloc_report(MALLOC_SIMPLE_STACK_LOGGING_FLAGS, "malloc (%p/%llu): ",
-				ptr, (unsigned long long)size);
-	}
-
-	MALLOC_TRACE(TRACE_malloc | DBG_FUNC_END, (uintptr_t)zone, size,
-			(uintptr_t)ptr, type_id);
-out:
-#if MALLOC_TARGET_64BIT
-	if (clear_type) {
-		malloc_set_tsd_type_descriptor(MALLOC_TYPE_DESCRIPTOR_NONE);
-	}
-#endif // MALLOC_TARGET_64BIT
-	if (os_unlikely(ptr == NULL)) {
-		malloc_set_errno_fast(mzo, ENOMEM);
-	}
-	return ptr;
-}
-
-void *
-_malloc_zone_malloc(malloc_zone_t *zone, size_t size, malloc_zone_options_t mzo)
-{
-	if (zone == default_zone && !lite_zone) {
-		// Eagerly resolve the virtual default zone to make the zone version
-		// check accurate
-		zone = malloc_zones[0];
-	}
-
-	if (os_unlikely(malloc_slowpath || malloc_logger || zone->version < 13)) {
-		return _malloc_zone_malloc_instrumented_or_legacy(zone, size, mzo);
-	}
-
-	if (os_unlikely(size > malloc_absolute_max_size)) {
-		malloc_set_errno_fast(mzo, ENOMEM);
-		return NULL;
-	}
-
-	if (zone->version >= 16) {
-		return zone->malloc_type_malloc(zone, size,
-				malloc_callsite_fallback_type_id());
-	}
-
-	// zone versions >= 13 set errno on failure so we can tail-call
-	return zone->malloc(zone, size);
-}
-
-MALLOC_NOINLINE
 void *
 malloc_zone_malloc(malloc_zone_t *zone, size_t size)
 {
-	return _malloc_zone_malloc(zone, size, MZ_NONE);
-}
-
-MALLOC_NOINLINE
-static void *
-_malloc_zone_calloc_instrumented_or_legacy(malloc_zone_t *zone,
-		size_t num_items, size_t size, malloc_zone_options_t mzo)
-{
-	uint64_t type_id = malloc_get_tsd_type_id();
-#if MALLOC_TARGET_64BIT
-	bool clear_type = false;
-	if (!type_id) {
-		malloc_type_descriptor_t fallback =
-				malloc_callsite_fallback_type_descriptor();
-		malloc_set_tsd_type_descriptor(fallback);
-		type_id = fallback.type_id;
-		clear_type = true;
-	}
-#endif // MALLOC_TARGET_64BIT
-	MALLOC_TRACE(TRACE_calloc | DBG_FUNC_START, (uintptr_t)zone, num_items,
-			size, type_id);
+	MALLOC_TRACE(TRACE_malloc | DBG_FUNC_START, (uintptr_t)zone, size, 0, 0);
 
 	void *ptr;
-	if (malloc_check_start) {
+	if (malloc_check_start && (malloc_check_counter++ >= malloc_check_start)) {
 		internal_check();
 	}
-
-	ptr = zone->calloc(zone, num_items, size);
-
-	if (os_unlikely(malloc_logger)) {
-		uint32_t logger_type = MALLOC_LOG_TYPE_ALLOCATE |
-				MALLOC_LOG_TYPE_HAS_ZONE | MALLOC_LOG_TYPE_CLEARED;
-		malloc_logger(logger_type, (uintptr_t)zone,
-				(uintptr_t)(num_items * size), 0, (uintptr_t)ptr, 0);
-	}
-
-	if (os_unlikely(malloc_simple_stack_logging)) {
-		malloc_report(MALLOC_SIMPLE_STACK_LOGGING_FLAGS,
-				"calloc (%p/%llu*%llu): ", ptr, (unsigned long long)num_items,
-				(unsigned long long)size);
-	}
-
-	MALLOC_TRACE(TRACE_calloc | DBG_FUNC_END, (uintptr_t)zone, num_items, size,
-			(uintptr_t)ptr);
-#if MALLOC_TARGET_64BIT
-	if (clear_type) {
-		malloc_set_tsd_type_descriptor(MALLOC_TYPE_DESCRIPTOR_NONE);
-	}
-#endif // MALLOC_TARGET_64BIT
-	if (os_unlikely(ptr == NULL)) {
-		malloc_set_errno_fast(mzo, ENOMEM);
-	}
+	if (size > MALLOC_ABSOLUTE_MAX_SIZE) {
+		return NULL;
+	}
+
+	ptr = zone->malloc(zone, size);		// if lite zone is passed in then we still call the lite methods
+
+	
+	if (malloc_logger) {
+		malloc_logger(MALLOC_LOG_TYPE_ALLOCATE | MALLOC_LOG_TYPE_HAS_ZONE, (uintptr_t)zone, (uintptr_t)size, 0, (uintptr_t)ptr, 0);
+	}
+
+	MALLOC_TRACE(TRACE_malloc | DBG_FUNC_END, (uintptr_t)zone, size, (uintptr_t)ptr, 0);
 	return ptr;
 }
 
-MALLOC_NOINLINE
-void *
-_malloc_zone_calloc(malloc_zone_t *zone, size_t num_items, size_t size,
-		malloc_zone_options_t mzo)
-{
-	if (zone == default_zone && !lite_zone) {
-		// Eagerly resolve the virtual default zone to make the zone version
-		// check accurate
-		zone = malloc_zones[0];
-	}
-
-	if (os_unlikely(malloc_slowpath || malloc_logger || zone->version < 13)) {
-		return _malloc_zone_calloc_instrumented_or_legacy(zone, num_items, size, mzo);
-	}
-
-	if (zone->version >= 16) {
-		return zone->malloc_type_calloc(zone, num_items, size,
-				malloc_callsite_fallback_type_id());
-	}
-
-	// zone versions >= 13 set errno on failure so we can tail-call
-	return zone->calloc(zone, num_items, size);
-}
-
-MALLOC_NOINLINE
 void *
 malloc_zone_calloc(malloc_zone_t *zone, size_t num_items, size_t size)
 {
-	return _malloc_zone_calloc(zone, num_items, size, MZ_NONE);
-}
-
-MALLOC_NOINLINE
-void *
-_malloc_zone_valloc(malloc_zone_t *zone, size_t size, malloc_zone_options_t mzo)
-{
-	uint64_t type_id = malloc_get_tsd_type_id();
-#if MALLOC_TARGET_64BIT
-	bool clear_type = false;
-	if (!type_id) {
-		malloc_type_descriptor_t fallback =
-				malloc_callsite_fallback_type_descriptor();
-		malloc_set_tsd_type_descriptor(fallback);
-		type_id = fallback.type_id;
-		clear_type = true;
-	}
-#endif // MALLOC_TARGET_64BIT
-	MALLOC_TRACE(TRACE_valloc | DBG_FUNC_START, (uintptr_t)zone, size, type_id,
-			0);
-
-	void *ptr = NULL;
-	if (malloc_check_start) {
+	MALLOC_TRACE(TRACE_calloc | DBG_FUNC_START, (uintptr_t)zone, num_items, size, 0);
+
+	void *ptr;
+	if (malloc_check_start && (malloc_check_counter++ >= malloc_check_start)) {
 		internal_check();
 	}
-	if (size > malloc_absolute_max_size) {
-		goto out;
-	}
-
-	ptr = zone->valloc(zone, size);
-
-	if (os_unlikely(malloc_logger)) {
-		malloc_logger(MALLOC_LOG_TYPE_ALLOCATE | MALLOC_LOG_TYPE_HAS_ZONE,
-				(uintptr_t)zone, (uintptr_t)size, 0, (uintptr_t)ptr, 0);
-	}
-
-	if (os_unlikely(malloc_simple_stack_logging)) {
-		malloc_report(MALLOC_SIMPLE_STACK_LOGGING_FLAGS, "valloc (%p/%llu): ",
-				ptr, (unsigned long long)size);
-	}
-
-	MALLOC_TRACE(TRACE_valloc | DBG_FUNC_END, (uintptr_t)zone, size,
-			(uintptr_t)ptr, type_id);
-out:
-#if MALLOC_TARGET_64BIT
-	if (clear_type) {
-		malloc_set_tsd_type_descriptor(MALLOC_TYPE_DESCRIPTOR_NONE);
-	}
-#endif // MALLOC_TARGET_64BIT
-
-	if (os_unlikely(ptr == NULL)) {
-		malloc_set_errno_fast(mzo, ENOMEM);
-	}
+
+	ptr = zone->calloc(zone, num_items, size);
+	
+	if (malloc_logger) {
+		malloc_logger(MALLOC_LOG_TYPE_ALLOCATE | MALLOC_LOG_TYPE_HAS_ZONE | MALLOC_LOG_TYPE_CLEARED, (uintptr_t)zone,
+				(uintptr_t)(num_items * size), 0, (uintptr_t)ptr, 0);
+	}
+
+	MALLOC_TRACE(TRACE_calloc | DBG_FUNC_END, (uintptr_t)zone, num_items, size, (uintptr_t)ptr);
 	return ptr;
 }
 
-MALLOC_NOINLINE
 void *
 malloc_zone_valloc(malloc_zone_t *zone, size_t size)
 {
-	return _malloc_zone_valloc(zone, size, MZ_NONE);
-}
-
-// We have this function so code within libmalloc can call it without going
-// through the (potentially interposed) dyld symbol stub
-void *
-_malloc_zone_realloc(malloc_zone_t *zone, void *ptr, size_t size,
-		malloc_type_descriptor_t type_desc)
-{
-	uint64_t type_id = malloc_get_tsd_type_id();
-#if MALLOC_TARGET_64BIT
-	bool clear_type = false;
-	if (!type_id) {
-		// A type descriptor in the TSD takes precendence over one passed as a
-		// parameter - the one in the TSD will be a real one set by e.g.
-		// _malloc_type_realloc_outlined(), whereas the parameter will be a
-		// callsite-derived fallback
-		malloc_set_tsd_type_descriptor(type_desc);
-		type_id = type_desc.type_id;
-		clear_type = true;
-	}
-#endif // MALLOC_TARGET_64BIT
-	MALLOC_TRACE(TRACE_realloc | DBG_FUNC_START, (uintptr_t)zone,
-			(uintptr_t)ptr, size, type_id);
-
-	void *new_ptr = NULL;
-	if (malloc_check_start) {
+	MALLOC_TRACE(TRACE_valloc | DBG_FUNC_START, (uintptr_t)zone, size, 0, 0);
+
+	void *ptr;
+	if (malloc_check_start && (malloc_check_counter++ >= malloc_check_start)) {
 		internal_check();
 	}
-	if (size > malloc_absolute_max_size) {
-		goto out;
-	}
-
-	new_ptr = zone->realloc(zone, ptr, size);
-	
-	if (os_unlikely(malloc_logger)) {
-		uint32_t logger_type = MALLOC_LOG_TYPE_ALLOCATE |
-			MALLOC_LOG_TYPE_DEALLOCATE | MALLOC_LOG_TYPE_HAS_ZONE;
-		malloc_logger(logger_type, (uintptr_t)zone, (uintptr_t)ptr,
-				(uintptr_t)size, (uintptr_t)new_ptr, 0);
-	}
-
-	if (os_unlikely(malloc_simple_stack_logging)) {
-		malloc_report(MALLOC_SIMPLE_STACK_LOGGING_FLAGS,
-				"realloc (%p->%p/%llu): ", ptr, new_ptr,
-				(unsigned long long)size);
-	}
-
-	MALLOC_TRACE(TRACE_realloc | DBG_FUNC_END, (uintptr_t)zone, (uintptr_t)ptr,
-			size, (uintptr_t)new_ptr);
-out:
-#if MALLOC_TARGET_64BIT
-	if (clear_type) {
-		malloc_set_tsd_type_descriptor(MALLOC_TYPE_DESCRIPTOR_NONE);
-	}
-#endif // MALLOC_TARGET_64BIT
-	return new_ptr;
-}
-
-MALLOC_NOINLINE
+	if (size > MALLOC_ABSOLUTE_MAX_SIZE) {
+		return NULL;
+	}
+
+	ptr = zone->valloc(zone, size);
+	
+	if (malloc_logger) {
+		malloc_logger(MALLOC_LOG_TYPE_ALLOCATE | MALLOC_LOG_TYPE_HAS_ZONE, (uintptr_t)zone, (uintptr_t)size, 0, (uintptr_t)ptr, 0);
+	}
+
+	MALLOC_TRACE(TRACE_valloc | DBG_FUNC_END, (uintptr_t)zone, size, (uintptr_t)ptr, 0);
+	return ptr;
+}
+
 void *
 malloc_zone_realloc(malloc_zone_t *zone, void *ptr, size_t size)
 {
-	return _malloc_zone_realloc(zone, ptr, size,
-			malloc_callsite_fallback_type_descriptor());
-}
-
-MALLOC_NOINLINE
+	MALLOC_TRACE(TRACE_realloc | DBG_FUNC_START, (uintptr_t)zone, (uintptr_t)ptr, size, 0);
+
+	void *new_ptr;
+	if (malloc_check_start && (malloc_check_counter++ >= malloc_check_start)) {
+		internal_check();
+	}
+	if (size > MALLOC_ABSOLUTE_MAX_SIZE) {
+		return NULL;
+	}
+
+	new_ptr = zone->realloc(zone, ptr, size);
+	
+	if (malloc_logger) {
+		malloc_logger(MALLOC_LOG_TYPE_ALLOCATE | MALLOC_LOG_TYPE_DEALLOCATE | MALLOC_LOG_TYPE_HAS_ZONE, (uintptr_t)zone,
+				(uintptr_t)ptr, (uintptr_t)size, (uintptr_t)new_ptr, 0);
+	}
+	MALLOC_TRACE(TRACE_realloc | DBG_FUNC_END, (uintptr_t)zone, (uintptr_t)ptr, size, (uintptr_t)new_ptr);
+	return new_ptr;
+}
+
 void
 malloc_zone_free(malloc_zone_t *zone, void *ptr)
 {
 	MALLOC_TRACE(TRACE_free, (uintptr_t)zone, (uintptr_t)ptr, (ptr) ? *(uintptr_t*)ptr : 0, 0);
 
-	if (os_unlikely(malloc_logger)) {
+	if (malloc_logger) {
 		malloc_logger(MALLOC_LOG_TYPE_DEALLOCATE | MALLOC_LOG_TYPE_HAS_ZONE, (uintptr_t)zone, (uintptr_t)ptr, 0, 0, 0);
 	}
-	if (os_unlikely(malloc_simple_stack_logging)) {
-		malloc_report(MALLOC_SIMPLE_STACK_LOGGING_FLAGS, "malloc_zone_free (%p): ", ptr);
-	}
-	if (malloc_check_start) {
+	if (malloc_check_start && (malloc_check_counter++ >= malloc_check_start)) {
 		internal_check();
 	}
 
@@ -2827,14 +1487,10 @@
 {
 	MALLOC_TRACE(TRACE_free, (uintptr_t)zone, (uintptr_t)ptr, size, (ptr && size) ? *(uintptr_t*)ptr : 0);
 
-	if (os_unlikely(malloc_logger)) {
+	if (malloc_logger) {
 		malloc_logger(MALLOC_LOG_TYPE_DEALLOCATE | MALLOC_LOG_TYPE_HAS_ZONE, (uintptr_t)zone, (uintptr_t)ptr, 0, 0, 0);
 	}
-	if (os_unlikely(malloc_simple_stack_logging)) {
-		malloc_report(MALLOC_SIMPLE_STACK_LOGGING_FLAGS, "free (%p/%llu): ",
-				ptr, (unsigned long long)size);
-	}
-	if (malloc_check_start) {
+	if (malloc_check_start && (malloc_check_counter++ >= malloc_check_start)) {
 		internal_check();
 	}
 
@@ -2847,96 +1503,41 @@
 	if (!ptr) {
 		return NULL;
 	} else {
-		return _find_registered_zone(ptr, NULL, false);
-	}
-}
-
-MALLOC_NOINLINE
-void *
-_malloc_zone_memalign(malloc_zone_t *zone, size_t alignment, size_t size,
-		malloc_zone_options_t mzo, malloc_type_descriptor_t type_desc)
-{
-	uint64_t type_id = malloc_get_tsd_type_id();
-#if MALLOC_TARGET_64BIT
-	bool clear_type = false;
-	if (!type_id) {
-		// A type descriptor in the TSD takes precendence over one passed as a
-		// parameter - the one in the TSD will be a real one set by e.g.
-		// _malloc_type_aligned_alloc_outlined(), whereas the parameter will
-		// usually be a callsite-derived fallback
-		malloc_set_tsd_type_descriptor(type_desc);
-		type_id = type_desc.type_id;
-		clear_type = true;
-	}
-#endif // MALLOC_TARGET_64BIT
-	MALLOC_TRACE(TRACE_memalign | DBG_FUNC_START, (uintptr_t)zone, alignment,
-			size, type_id);
-
-	void *ptr = NULL;
-	int err = ENOMEM;
-	// Version must be >= 5 to look at the new memalign field.
-	if (zone->version < 5) {
-		goto out;
-	}
-	if (malloc_check_start) {
-		internal_check();
-	}
-	if (size > malloc_absolute_max_size) {
-		goto out;
-	}
-	// excludes 0 == alignment
-	// relies on sizeof(void *) being a power of two.
-	if (alignment < MALLOC_ZONE_MALLOC_DEFAULT_ALIGN ||
-			0 != (alignment & (alignment - 1))) {
-		err = EINVAL;
-		goto out;
-	}
-	// C11 aligned_alloc requires size to be a multiple of alignment, but
-	// posix_memalign does not
-	if ((mzo & MZ_C11) && (size & (alignment - 1)) != 0) {
-		err = EINVAL;
-		goto out;
-	}
-
-	if (!(zone->memalign)) {
-		goto out;
-	}
-	ptr = zone->memalign(zone, alignment, size);
-
-	if (os_unlikely(malloc_logger)) {
-		malloc_logger(MALLOC_LOG_TYPE_ALLOCATE | MALLOC_LOG_TYPE_HAS_ZONE,
-				(uintptr_t)zone, (uintptr_t)size, 0, (uintptr_t)ptr, 0);
-	}
-	if (os_unlikely(malloc_simple_stack_logging)) {
-		malloc_report(MALLOC_SIMPLE_STACK_LOGGING_FLAGS,
-				"memalign (%p/%llu,%llu): ", ptr, (unsigned long long)alignment,
-				(unsigned long long)size);
-	}
-
-	MALLOC_TRACE(TRACE_memalign | DBG_FUNC_END, (uintptr_t)zone, alignment,
-			size, (uintptr_t)ptr);
-
-out:
-#if MALLOC_TARGET_64BIT
-	if (clear_type) {
-		malloc_set_tsd_type_descriptor(MALLOC_TYPE_DESCRIPTOR_NONE);
-	}
-#endif // MALLOC_TARGET_64BIT
-
-	if (os_unlikely(ptr == NULL)) {
-		if (mzo & MZ_POSIX) {
-			malloc_set_errno_fast(mzo, err);
-		}
-	}
-	return ptr;
-}
-
-MALLOC_NOINLINE
+		return find_registered_zone(ptr, NULL);
+	}
+}
+
 void *
 malloc_zone_memalign(malloc_zone_t *zone, size_t alignment, size_t size)
 {
-	return _malloc_zone_memalign(zone, alignment, size, MZ_NONE,
-			malloc_callsite_fallback_type_descriptor());
+	MALLOC_TRACE(TRACE_memalign | DBG_FUNC_START, (uintptr_t)zone, alignment, size, 0);
+
+	void *ptr;
+	if (zone->version < 5) { // Version must be >= 5 to look at the new memalign field.
+		return NULL;
+	}
+	if (malloc_check_start && (malloc_check_counter++ >= malloc_check_start)) {
+		internal_check();
+	}
+	if (size > MALLOC_ABSOLUTE_MAX_SIZE) {
+		return NULL;
+	}
+	if (alignment < sizeof(void *) ||			  // excludes 0 == alignment
+			0 != (alignment & (alignment - 1))) { // relies on sizeof(void *) being a power of two.
+		return NULL;
+	}
+
+	if (!(zone->memalign)) {
+		return NULL;
+	}
+	ptr = zone->memalign(zone, alignment, size);
+
+	if (malloc_logger) {
+		malloc_logger(MALLOC_LOG_TYPE_ALLOCATE | MALLOC_LOG_TYPE_HAS_ZONE, (uintptr_t)zone, (uintptr_t)size, 0, (uintptr_t)ptr, 0);
+	}
+
+	MALLOC_TRACE(TRACE_memalign | DBG_FUNC_END, (uintptr_t)zone, alignment, size, (uintptr_t)ptr);
+	return ptr;
 }
 
 boolean_t
@@ -2947,7 +1548,7 @@
 		return false;
 	}
 
-	if (malloc_check_start) {
+	if (malloc_check_start && (malloc_check_counter++ >= malloc_check_start)) {
 		internal_check();
 	}
 
@@ -2966,7 +1567,7 @@
 malloc_zone_register(malloc_zone_t *zone)
 {
 	MALLOC_LOCK();
-	malloc_zone_register_while_locked(zone, false);
+	malloc_zone_register_while_locked(zone);
 	MALLOC_UNLOCK();
 }
 
@@ -2997,10 +1598,6 @@
 		--malloc_num_zones;
 
 		mprotect(malloc_zones, protect_size, PROT_READ);
-
-		// MAX(num_zones, 1) retains the fast path in find_registered_zone() for zone 0 even
-		// if it is a custom zone, e.g., ASan and user zones.
-		initial_num_zones = MAX(MIN(malloc_num_zones, initial_num_zones), 1);
 
 		// Exchange the roles of the FRZ counters. The counter that has captured the number of threads presently
 		// executing *inside* find_registered_zone is swapped with the counter drained to zero last time through.
@@ -3025,60 +1622,24 @@
 void
 malloc_set_zone_name(malloc_zone_t *z, const char *name)
 {
-	// TODO: save and restore permissions generally
-	bool mprotect_zone = true;
-#if CONFIG_XZONE_MALLOC
-	if (_xzm_malloc_zone_is_xzm(z)) {
-		mprotect_zone = false;
-	}
-#endif // CONFIG_XZONE_MALLOC
-	if (mprotect_zone) {
-		mprotect(z, sizeof(malloc_zone_t), PROT_READ | PROT_WRITE);
-	}
+	char *newName;
+
+	mprotect(z, sizeof(malloc_zone_t), PROT_READ | PROT_WRITE);
 	if (z->zone_name) {
-		malloc_zone_t *old_zone = _find_registered_zone(z->zone_name, NULL, false);
-		if (old_zone) {
-			malloc_zone_free(old_zone, (char *)z->zone_name);
-		}
+		free((char *)z->zone_name);
 		z->zone_name = NULL;
 	}
 	if (name) {
 		size_t buflen = strlen(name) + 1;
-		if (_dyld_is_memory_immutable(name, buflen)) {
-			z->zone_name = name;
+		newName = malloc_zone_malloc(z, buflen);
+		if (newName) {
+			strlcpy(newName, name, buflen);
+			z->zone_name = (const char *)newName;
 		} else {
-			char *name_copy = _malloc_zone_malloc(z, buflen, MZ_NONE);
-			if (name_copy) {
-				strcpy(name_copy, name);
-				z->zone_name = name_copy;
-			}
-		}
-
-		malloc_zone_t *wrapped_zone = get_wrapped_zone(z);
-		if (wrapped_zone) {
-			// <name>-<wrapper_label>-<suffix>\0  // Wrapped zone name format
-			//       ^               ^        ^   // 2 dashes and \0 -> +3
-			const char *wrapper_label = get_wrapper_zone_label(z);
-			const char *suffix = "Wrapped";
-			size_t buflen = strlen(name) + strlen(wrapper_label) + strlen(suffix) + 3;
-			char *wz_name = _malloc_zone_malloc(wrapped_zone, buflen, MZ_NONE);
-			if (wz_name) {
-				// snprintf() may allocate (not safe to use from libmalloc) and
-				// _simple_sprintf()/_simple_salloc() call vm_allocate() which is
-				// undesirable for such a simple API as malloc_set_zone_name()
-				strcpy(wz_name, name);
-				strcat(wz_name, "-");
-				strcat(wz_name, wrapper_label);
-				strcat(wz_name, "-");
-				strcat(wz_name, suffix);
-				malloc_set_zone_name(wrapped_zone, wz_name);
-				malloc_zone_free(wrapped_zone, wz_name);
-			}
-		}
-	}
-	if (mprotect_zone) {
-		mprotect(z, sizeof(malloc_zone_t), PROT_READ);
-	}
+			z->zone_name = NULL;
+		}
+	}
+	mprotect(z, sizeof(malloc_zone_t), PROT_READ);
 }
 
 const char *
@@ -3087,8 +1648,49 @@
 	return zone->zone_name;
 }
 
-void
-find_zone_and_free(void *ptr, bool known_non_default)
+
+/*********	Generic ANSI callouts	************/
+
+void *
+malloc(size_t size)
+{
+	void *retval;
+	retval = malloc_zone_malloc(default_zone, size);
+	if (retval == NULL) {
+		errno = ENOMEM;
+	}
+	return retval;
+}
+
+void *
+aligned_alloc(size_t alignment, size_t size)
+{
+	if (alignment < sizeof(void *) || !powerof2(alignment) || /* those are implementation requirements */
+			(size & (alignment - 1)) != 0) { /* C11 requires size to be a multiple of alignment */
+		errno = EINVAL;
+		return NULL;
+	}
+
+	void *retval = malloc_zone_memalign(default_zone, alignment, size);
+	if (retval == NULL) {
+		errno = ENOMEM;
+	}
+	return retval;
+}
+
+void *
+calloc(size_t num_items, size_t size)
+{
+	void *retval;
+	retval = malloc_zone_calloc(default_zone, num_items, size);
+	if (retval == NULL) {
+		errno = ENOMEM;
+	}
+	return retval;
+}
+
+void
+free(void *ptr)
 {
 	malloc_zone_t *zone;
 	size_t size;
@@ -3096,27 +1698,14 @@
 		return;
 	}
 
-	zone = _find_registered_zone(ptr, &size, known_non_default);
+	zone = find_registered_zone(ptr, &size);
 	if (!zone) {
 		int flags = MALLOC_REPORT_DEBUG | MALLOC_REPORT_NOLOG;
 		if ((malloc_debug_flags & (MALLOC_ABORT_ON_CORRUPTION | MALLOC_ABORT_ON_ERROR))) {
 			flags = MALLOC_REPORT_CRASH | MALLOC_REPORT_NOLOG;
 		}
-#if CONFIG_MTE
-		// When tagging is enabled, this will validate the MTE tag of the
-		// pointer and raise a fatal exception if it doesn't match the tag
-		// stored in memory.
-		//
-		// We need to do this here to cover the following deviations along the
-		// free() path:
-		// - when we are called directly by _free(), in the cases where we can't
-		//   invoke zone->try_free_default()
-		// - in xzone, in the outlined path after the pointer lookup has failed,
-		//   if we're in a try context
-		// - in xzone, from the slow path for try_free_default(), if the zone
-		//   lookup fails when trying to determine the size of the allocation
-#endif
-		malloc_report_pointer_was_not_allocated(flags, ptr);
+		malloc_report(flags,
+				"*** error for object %p: pointer being freed was not allocated\n", ptr);
 	} else if (zone->version >= 6 && zone->free_definite_size) {
 		malloc_zone_free_definite_size(zone, ptr, size);
 	} else {
@@ -3124,68 +1713,11 @@
 	}
 }
 
-
-/*********	Generic ANSI callouts	************/
-
-MALLOC_NOINLINE
 void *
-malloc(size_t size)
-{
-	return _malloc_zone_malloc(default_zone, size, MZ_POSIX);
-}
-
-MALLOC_NOINLINE
-void *
-aligned_alloc(size_t alignment, size_t size)
-{
-	return _malloc_zone_memalign(default_zone, alignment, size,
-	    MZ_POSIX | MZ_C11, malloc_callsite_fallback_type_descriptor());
-}
-
-MALLOC_NOINLINE
-void *
-calloc(size_t num_items, size_t size)
-{
-	return _malloc_zone_calloc(default_zone, num_items, size, MZ_POSIX);
-}
-
-// We have this function so code within libmalloc can call it without going
-// through the (potentially interposed) dyld symbol stub
-void
-_free(void *ptr)
-{
-	if (!ptr) {
-		return;
-	}
-
-	malloc_zone_t *zone0 = malloc_zones[0];
-	if (os_unlikely(malloc_slowpath ||
-				malloc_logger ||
-				zone0->version < 13)) {
-		find_zone_and_free(ptr, false);
-		return;
-	}
-
-	if (zone0->try_free_default) {
-		zone0->try_free_default(zone0, ptr);
-	} else {
-		find_zone_and_free(ptr, false);
-	}
-}
-
-MALLOC_NOINLINE
-void
-free(void *ptr)
-{
-	return _free(ptr);
-}
-
-// We have this function so code within libmalloc can call it without going
-// through the (potentially interposed) dyld symbol stub
-void *
-_realloc(void *in_ptr, size_t new_size)
+realloc(void *in_ptr, size_t new_size)
 {
 	void *retval = NULL;
+	void *old_ptr;
 	malloc_zone_t *zone;
 
 	// SUSv3: "If size is 0 and ptr is not a null pointer, the object
@@ -3196,91 +1728,46 @@
 	// malloc_zone_malloc with zero size, which matches "If ptr is a null
 	// pointer, realloc() shall be equivalent to malloc() for the specified
 	// size."  So we only free the original memory if the allocation succeeds.
-	//
-	// When in_ptr is NULL, we want to ensure that the fallback type descriptor
-	// is good.  We can ensure that by tail-calling from here, so that the
-	// callsite information is accurate.
-	//
-	// We don't really care about the quality of the type descriptor
-	// for the new_size == 0 allocation, so it's fine for it to always be based
-	// on the callsite in this function.
-	//
-	// Note: the fact that we allocate from the default zone in the
-	// new_size == 0 case regardless of the zone in_ptr belongs to is arguably a
-	// bug.
-	if (!in_ptr) {
-		return _malloc_zone_malloc(default_zone, new_size, MZ_POSIX);
-	} else if (new_size == 0) {
-		retval = _malloc_zone_malloc(default_zone, new_size, MZ_NONE);
+	old_ptr = (new_size == 0) ? NULL : in_ptr;
+	if (!old_ptr) {
+		retval = malloc_zone_malloc(default_zone, new_size);
 	} else {
-		zone = _find_registered_zone(in_ptr, NULL, false);
+		zone = find_registered_zone(old_ptr, NULL);
 		if (!zone) {
-#if CONFIG_MTE
-			// This will validate the MTE tag of the pointer: this is required
-			// to make sure we raise a fatal exception when trying to reallocate
-			// a pointer with an invalid tag.
-			// Note that this is the only place where we handle this in the
-			// realloc path: for malloc_type_realloc, this means that we only
-			// validate the MTE tag when the zone lookup fails in the fast path,
-			// or in the slow path only if the symbol has not been interposed.
-#endif
 			int flags = MALLOC_REPORT_DEBUG | MALLOC_REPORT_NOLOG;
-			const int abort_flags =
-					(MALLOC_ABORT_ON_CORRUPTION | MALLOC_ABORT_ON_ERROR);
-			if (malloc_debug_flags & abort_flags) {
+			if (malloc_debug_flags & (MALLOC_ABORT_ON_CORRUPTION | MALLOC_ABORT_ON_ERROR)) {
 				flags = MALLOC_REPORT_CRASH | MALLOC_REPORT_NOLOG;
 			}
-			malloc_report_pointer_was_not_allocated(flags, in_ptr);
+			malloc_report(flags, "*** error for object %p: pointer being realloc'd was not allocated\n", in_ptr);
 		} else {
-			retval = _malloc_zone_realloc(zone, in_ptr, new_size,
-					malloc_callsite_fallback_type_descriptor());
+			retval = malloc_zone_realloc(zone, old_ptr, new_size);
 		}
 	}
 
 	if (retval == NULL) {
-		malloc_set_errno_fast(MZ_POSIX, ENOMEM);
+		errno = ENOMEM;
 	} else if (new_size == 0) {
-		_free(in_ptr);
+		free(in_ptr);
 	}
 	return retval;
 }
 
-MALLOC_NOINLINE
-void *
-realloc(void *in_ptr, size_t new_size)
-{
-	return _realloc(in_ptr, new_size);
-}
-
-MALLOC_NOINLINE
-void *
-reallocf(void *in_ptr, size_t new_size)
-{
-	void *ptr = realloc(in_ptr, new_size);
-
-	if (!ptr && in_ptr && new_size != 0) {
-		// Save and restore `errno`, because `realloc` will set it to ENOMEM
-		// on allocation failure, but it could be overwritten if `free` calls
-		// into a library function that also modifies `errno`
-		errno_t error = errno;
-		free(in_ptr);
-		errno = error;
-	}
-
-	return ptr;
-}
-
-MALLOC_NOINLINE
 void *
 valloc(size_t size)
 {
-	return _malloc_zone_valloc(default_zone, size, MZ_POSIX);
+	void *retval;
+	malloc_zone_t *zone = default_zone;
+	retval = malloc_zone_valloc(zone, size);
+	if (retval == NULL) {
+		errno = ENOMEM;
+	}
+	return retval;
 }
 
 extern void
 vfree(void *ptr)
 {
-	_free(ptr);
+	free(ptr);
 }
 
 size_t
@@ -3292,7 +1779,7 @@
 		return size;
 	}
 
-	(void)_find_registered_zone(ptr, &size, false);
+	(void)find_registered_zone(ptr, &size);
 	return size;
 }
 
@@ -3319,23 +1806,20 @@
  *	There is insufficient memory available with the requested alignment.
  */
 
-// We have this function so code within libmalloc can call it without going
-// through the (potentially interposed) dyld symbol stub
 int
-_posix_memalign(void **memptr, size_t alignment, size_t size)
+posix_memalign(void **memptr, size_t alignment, size_t size)
 {
 	void *retval;
 
 	/* POSIX is silent on NULL == memptr !?! */
 
-	retval = _malloc_zone_memalign(default_zone, alignment, size, MZ_NONE,
-			malloc_callsite_fallback_type_descriptor());
+	retval = malloc_zone_memalign(default_zone, alignment, size);
 	if (retval == NULL) {
 		// To avoid testing the alignment constraints redundantly, we'll rely on the
 		// test made in malloc_zone_memalign to vet each request. Only if that test fails
 		// and returns NULL, do we arrive here to detect the bogus alignment and give the
 		// required EINVAL return.
-		if (alignment < MALLOC_ZONE_MALLOC_DEFAULT_ALIGN || // excludes 0 == alignment
+		if (alignment < sizeof(void *) ||			  // excludes 0 == alignment
 				0 != (alignment & (alignment - 1))) { // relies on sizeof(void *) being a power of two.
 			return EINVAL;
 		}
@@ -3346,13 +1830,6 @@
 	}
 }
 
-MALLOC_NOINLINE
-int
-posix_memalign(void **memptr, size_t alignment, size_t size)
-{
-	return _posix_memalign(memptr, alignment, size);
-}
-
 boolean_t
 malloc_claimed_address(void *ptr)
 {
@@ -3367,11 +1844,9 @@
 		return true;
 	}
 
-	// Next, try the initial zones.
-	for (uint32_t i = 0; i < initial_num_zones; i++) {
-		if (malloc_zone_claimed_address(malloc_zones[i], ptr)) {
-			return true;
-		}
+	// Next, try the default zone, which is always present.
+	if (malloc_zone_claimed_address(malloc_zones[0], ptr)) {
+		return true;
 	}
 
 	// Try all the other zones. Increment the FRZ barrier so that we can
@@ -3381,9 +1856,10 @@
 	OSAtomicIncrement32Barrier(pFRZCounter);
 
 	int32_t limit = *(int32_t volatile *)&malloc_num_zones;
+	malloc_zone_t **zones = &malloc_zones[1];
 	boolean_t result = false;
-	for (uint32_t i = initial_num_zones; i < limit; i++) {
-		malloc_zone_t *zone = malloc_zones[i];
+	for (unsigned index = 1; index < limit; ++index, ++zones) {
+		malloc_zone_t *zone = *zones;
 		if (malloc_zone_claimed_address(zone, ptr)) {
 			result = true;
 			break;
@@ -3398,7 +1874,7 @@
 reallocarray(void * in_ptr, size_t nmemb, size_t size){
 	size_t alloc_size;
 	if (os_mul_overflow(nmemb, size, &alloc_size)){
-		malloc_set_errno_fast(MZ_POSIX, ENOMEM);
+		errno = ENOMEM;
 		return NULL;
 	}
 	return realloc(in_ptr, alloc_size);
@@ -3408,192 +1884,10 @@
 reallocarrayf(void * in_ptr, size_t nmemb, size_t size){
 	size_t alloc_size;
 	if (os_mul_overflow(nmemb, size, &alloc_size)){
-		malloc_set_errno_fast(MZ_POSIX, ENOMEM);
+		errno = ENOMEM;
 		return NULL;
 	}
 	return reallocf(in_ptr, alloc_size);
-}
-
-void *
-_malloc_zone_malloc_with_options_outlined(malloc_zone_t *zone, size_t align,
-		size_t size, malloc_zone_malloc_options_t options)
-{
-	void *ptr = NULL;
-
-	if (zone == NULL || zone == default_zone) {
-		zone = runtime_default_zone();
-	}
-
-#if MALLOC_TARGET_64BIT
-	uint64_t type_id = malloc_get_tsd_type_id();
-	bool clear_type = false;
-	if (!type_id) {
-		malloc_type_descriptor_t fallback =
-				malloc_callsite_fallback_type_descriptor();
-		malloc_set_tsd_type_descriptor(fallback);
-		type_id = fallback.type_id;
-		clear_type = true;
-	}
-#endif // MALLOC_TARGET_64BIT
-
-	if (malloc_interposition_compat || (zone->version < 15) ||
-			!zone->malloc_with_options) {
-		// There's no reasonable way to have the fallback callsite type
-		// descriptor work here.  That's okay, as it's uncommon and SPI, so its
-		// callers should be built with TMO.
-		const malloc_zone_malloc_options_t known_options =
-				MALLOC_ZONE_MALLOC_OPTION_CLEAR | MALLOC_NP_OPTION_CANONICAL_TAG;
-		if (options & ~known_options) {
-			malloc_zone_error(MALLOC_ABORT_ON_ERROR, true,
-					"malloc_zone_malloc_with_options: unsupported options 0x%llx\n",
-					options);
-			__builtin_trap();
-		}
-
-#if CONFIG_MTE
-		// rdar://140822174
-		// When dyld interposition or a wrapper zone that does not support
-		// forwarding malloc options is enabled, we need to set a flag in the
-		// TSD to preserve the semantics of canonical tagging.
-		malloc_thread_options_t opts;
-		if ((options & MALLOC_ZONE_MALLOC_OPTION_CANONICAL_TAG) &&
-				malloc_has_sec_transition) {
-			opts = malloc_get_thread_options();
-			malloc_thread_options_t newopts = opts;
-			newopts.ReservedFlag = true;
-			_malloc_set_thread_options(newopts);
-		}
-#endif // CONFIG_MTE
-
-		if (align > MALLOC_ZONE_MALLOC_DEFAULT_ALIGN) {
-			ptr = malloc_zone_memalign(zone, align, size);
-			if (ptr && (options & MALLOC_ZONE_MALLOC_OPTION_CLEAR)) {
-				memset(ptr, 0, size);
-			}
-		} else if (options & MALLOC_ZONE_MALLOC_OPTION_CLEAR) {
-			ptr = malloc_zone_calloc(zone, 1, size);
-		} else {
-			ptr = malloc_zone_malloc(zone, size);
-		}
-
-#if CONFIG_MTE
-		// Restore the saved TSD flags
-		if ((options & MALLOC_ZONE_MALLOC_OPTION_CANONICAL_TAG) &&
-				malloc_has_sec_transition) {
-			_malloc_set_thread_options(opts);
-		}
-#endif // CONFIG_MTE
-	} else {
-		MALLOC_TRACE(TRACE_malloc_options | DBG_FUNC_START, (uintptr_t)zone,
-				align, size, 0);
-		ptr = zone->malloc_with_options(zone, align, size, options);
-
-		if (os_unlikely(malloc_logger)) {
-			uint32_t flags = MALLOC_LOG_TYPE_ALLOCATE | MALLOC_LOG_TYPE_HAS_ZONE;
-			if (options & MALLOC_ZONE_MALLOC_OPTION_CLEAR) {
-				flags |= MALLOC_LOG_TYPE_CLEARED;
-			}
-			malloc_logger(flags, (uintptr_t)zone, (uintptr_t)size,
-					0, (uintptr_t)ptr, 0);
-		}
-		if (os_unlikely(malloc_simple_stack_logging)) {
-			malloc_report(MALLOC_SIMPLE_STACK_LOGGING_FLAGS,
-					"malloc_with_options (%p/%llu,%llu): ", ptr,
-					(unsigned long long)align, (unsigned long long)size);
-		}
-		MALLOC_TRACE(TRACE_malloc_options | DBG_FUNC_END,
-				(uintptr_t)zone, align, size, (uintptr_t)ptr);
-	}
-
-#if MALLOC_TARGET_64BIT
-	if (clear_type) {
-		malloc_set_tsd_type_descriptor(MALLOC_TYPE_DESCRIPTOR_NONE);
-	}
-#endif
-
-	return ptr;
-}
-
-void *
-malloc_zone_malloc_with_options(malloc_zone_t *zone, size_t align,
-		size_t size, malloc_zone_malloc_options_t options)
-{
-	if (align != MALLOC_ZONE_MALLOC_DEFAULT_ALIGN &&
-			(os_unlikely((align != 0) && (!powerof2(align) ||
-			((size & (align-1)) != 0))))) { // equivalent to (size % align != 0)
-		return NULL;
-	}
-
-	if (os_unlikely(malloc_logger || malloc_slowpath)) {
-		return _malloc_zone_malloc_with_options_outlined(zone, align, size,
-				options);
-	}
-
-	if (zone == NULL || zone == default_zone) {
-		zone = malloc_zones[0];
-	}
-
-	if (zone->version >= 16 && zone->malloc_type_malloc_with_options) {
-		return zone->malloc_type_malloc_with_options(zone, align, size,
-				options, malloc_callsite_fallback_type_id());
-	}
-
-	return _malloc_zone_malloc_with_options_outlined(zone, align, size,
-			options);
-}
-
-void * __sized_by_or_null(size)
-malloc_zone_malloc_with_options_np(malloc_zone_t *zone, size_t align,
-		size_t size, malloc_options_np_t options)
-{
-	return malloc_zone_malloc_with_options(zone, align, size, options);
-}
-
-/*********	Purgeable zone	************/
-
-static void
-_malloc_create_purgeable_zone(void * __unused ctx)
-{
-#if CONFIG_XZONE_MALLOC
-	if (initial_xzone_zone && purgeable_zone_use_xzm) {
-		unsigned flags = malloc_debug_flags | MALLOC_PURGEABLE;
-		default_purgeable_zone = xzm_malloc_zone_create(flags,
-				(xzm_main_malloc_zone_t)initial_xzone_zone);
-		malloc_zone_register(default_purgeable_zone);
-		malloc_set_zone_name(default_purgeable_zone,
-				DEFAULT_PUREGEABLE_ZONE_STRING);
-		return;
-	}
-#endif // CONFIG_XZONE_MALLOC
-
-	//
-	// PR_7288598: Must pass a *scalable* zone (szone) as the helper for create_purgeable_zone().
-	// Take care that the zone so obtained is not subject to interposing.
-	//
-	if (!initial_scalable_zone) {
-		// If the process didn't initially create a scalable zone because xzone
-		// malloc is enabled, we should create one now.
-		//
-		// TODO: xzone-backed purgeable zone
-		initial_scalable_zone = create_scalable_zone(0, malloc_debug_flags);
-		malloc_set_zone_name(initial_scalable_zone,
-				DEFAULT_SCALABLE_ZONE_STRING);
-		malloc_zone_register(initial_scalable_zone);
-	}
-
-	default_purgeable_zone = create_purgeable_zone(0, initial_scalable_zone,
-			malloc_debug_flags);
-	malloc_zone_register(default_purgeable_zone);
-	malloc_set_zone_name(default_purgeable_zone,
-			DEFAULT_PUREGEABLE_ZONE_STRING);
-}
-
-malloc_zone_t *
-malloc_default_purgeable_zone(void)
-{
-	static os_once_t pred;
-	os_once(&pred, NULL, _malloc_create_purgeable_zone);
-	return default_purgeable_zone;
 }
 
 static malloc_zone_t *
@@ -3610,7 +1904,7 @@
 	 * and only search those.
 	 */
 	size_t size = 0;
-	malloc_zone_t *zone = _find_registered_zone(ptr, &size, false);
+	malloc_zone_t *zone = find_registered_zone(ptr, &size);
 
 	/* FIXME: would really like a zone->introspect->flags->purgeable check, but haven't determined
 	 * binary compatibility impact of changing the introspect struct yet. */
@@ -3659,32 +1953,32 @@
 	return 0;
 }
 
-/*********	Memory events	************/
-
 void
 malloc_enter_process_memory_limit_warn_mode(void)
 {
 	// <rdar://problem/25063714>
 }
 
+
+
 // Note that malloc_memory_event_handler is not thread-safe, and we are relying on the callers of this for synchronization
 void
 malloc_memory_event_handler(unsigned long event)
 {
-#if CONFIG_MADVISE_PRESSURE_RELIEF || (CONFIG_LARGE_CACHE && !CONFIG_MAGAZINE_DEFERRED_RECLAIM)
-	if (event & MALLOC_MEMORYSTATUS_MASK_PRESSURE_RELIEF) {
+	if (event & NOTE_MEMORYSTATUS_PRESSURE_WARN) {
 		malloc_zone_pressure_relief(0, 0);
 	}
-#endif /* CONFIG_MADVISE_PRESSURE_RELIEF || (CONFIG_LARGE_CACHE && !CONFIG_MAGAZINE_DEFERRED_RECLAIM) */
 
 	if ((event & NOTE_MEMORYSTATUS_MSL_STATUS) != 0 && (event & ~NOTE_MEMORYSTATUS_MSL_STATUS) == 0) {
 		malloc_register_stack_logger();
 	}
 
-	if (event & malloc_memorystatus_mask_resource_exception_handling) {
+#if ENABLE_MEMORY_RESOURCE_EXCEPTION_HANDLING
+	if (event & (NOTE_MEMORYSTATUS_PROC_LIMIT_WARN | NOTE_MEMORYSTATUS_PROC_LIMIT_CRITICAL | NOTE_MEMORYSTATUS_PRESSURE_CRITICAL)) {
 		malloc_register_stack_logger();
 	}
-
+#endif // ENABLE_MEMORY_RESOURCE_EXCEPTION_HANDLING
+	
 	if (msl.handle_memory_event) {
 		// Let MSL see the event.
 		msl.handle_memory_event(event);
@@ -3738,12 +2032,12 @@
 	if (!zone->batch_malloc) {
 		return 0;
 	}
-	if (malloc_check_start) {
+	if (malloc_check_start && (malloc_check_counter++ >= malloc_check_start)) {
 		internal_check();
 	}
 	unsigned batched = zone->batch_malloc(zone, size, results, num_requested);
 	
-	if (os_unlikely(malloc_logger)) {
+	if (malloc_logger) {
 		unsigned index = 0;
 		while (index < batched) {
 			malloc_logger(MALLOC_LOG_TYPE_ALLOCATE | MALLOC_LOG_TYPE_HAS_ZONE, (uintptr_t)zone, (uintptr_t)size, 0,
@@ -3757,10 +2051,10 @@
 void
 malloc_zone_batch_free(malloc_zone_t *zone, void **to_be_freed, unsigned num)
 {
-	if (malloc_check_start) {
+	if (malloc_check_start && (malloc_check_counter++ >= malloc_check_start)) {
 		internal_check();
 	}
-	if (os_unlikely(malloc_logger)) {
+	if (malloc_logger) {
 		unsigned index = 0;
 		while (index < num) {
 			malloc_logger(
@@ -3779,85 +2073,6 @@
 			free_fun(zone, ptr);
 		}
 	}
-}
-
-/*********  Functions for sanitization ************/
-
-#if TARGET_OS_OSX
-
-// Shadow memory helpers
-#define SHADOW_MEMORY_BASE (0x0000200000000000ull)
-#define SHADOW_GRANULARITY_BITS 3u
-#define SHADOW_GRANULARITY (1u << SHADOW_GRANULARITY_BITS)
-#define PTR_TO_SHADOW(p) (void *)((((uintptr_t)ptr) >> SHADOW_GRANULARITY_BITS) + SHADOW_MEMORY_BASE)
-#define SIZE_TO_SHADOW_SIZE(p) ((p) >> SHADOW_GRANULARITY_BITS)
-#define SHADOW_POISON_HEAP_LEFT_RZ 0xfa
-#define SHADOW_POISON_HEAP_RIGHT_RZ 0xfb
-#define SHADOW_POISON_HEAP_FREED 0xfd
-
-static void
-malloc_sanitizer_fallback_allocate_poison(uintptr_t ptr, size_t leftrz_sz, size_t alloc_sz, size_t rightrz_sz)
-{
-	uintptr_t alloc_ptr, rightrz_ptr;
-	MALLOC_ASSERT(!os_add_overflow(ptr, leftrz_sz, &alloc_ptr) &&
-				  !os_add_overflow(alloc_ptr, alloc_sz, &rightrz_ptr));
-
-	// Tag the ASan shadow as ASAN_POISON_USER/ASAN_VALID/ASAN_POISON_USER
-	if (sanitizer_fallback_ptrs.memory_poison && sanitizer_fallback_ptrs.memory_unpoison) {
-		(*sanitizer_fallback_ptrs.memory_poison)(ptr, leftrz_sz);
-		(*sanitizer_fallback_ptrs.memory_unpoison)(alloc_ptr, alloc_sz);
-		(*sanitizer_fallback_ptrs.memory_poison)(rightrz_ptr, rightrz_sz);
-	} else {
-		// This code should only be executed by Rosetta on macOS
-		MALLOC_ASSERT(!(leftrz_sz % SHADOW_GRANULARITY) &&
-					  !((alloc_sz + rightrz_sz) % SHADOW_GRANULARITY));
-
-		const uint8_t partial = alloc_sz & (SHADOW_GRANULARITY - 1);
-		// Partial poison is not supported, leave it unpoisoned
-		const size_t left = SIZE_TO_SHADOW_SIZE(leftrz_sz),
-					right = SIZE_TO_SHADOW_SIZE(rightrz_sz),
-					alloc = SIZE_TO_SHADOW_SIZE(alloc_sz) + !!partial;
-		uint8_t *shadow = PTR_TO_SHADOW(ptr);
-		memset(shadow, SHADOW_POISON_HEAP_LEFT_RZ, left);
-		shadow += left;
-		bzero(shadow + left, alloc);
-		shadow += alloc;
-		memset(shadow, SHADOW_POISON_HEAP_RIGHT_RZ, right);
-	}
-}
-
-static void
-malloc_sanitizer_fallback_deallocate_poison(uintptr_t ptr, size_t sz)
-{
-	// Tag the ASan shadow as ASAN_POISON_USER
-	if (sanitizer_fallback_ptrs.memory_poison) {
-		(*sanitizer_fallback_ptrs.memory_poison)(ptr, sz);
-	} else {
-		memset(PTR_TO_SHADOW(ptr), SHADOW_POISON_HEAP_FREED, SIZE_TO_SHADOW_SIZE(sz));
-	}
-}
-
-#endif // TARGET_OS_OSX
-
-bool malloc_sanitizer_is_enabled(void)
-{
-	return malloc_sanitizer_enabled;
-}
-
-const struct malloc_sanitizer_poison *
-malloc_sanitizer_get_functions(void)
-{
-#if TARGET_OS_OSX
-	return sanitizer ? sanitizer : &sanitizer_fallback;
-#else
-	return sanitizer;
-#endif
-}
-
-void
-malloc_sanitizer_set_functions(struct malloc_sanitizer_poison *s)
-{
-	sanitizer = s;
 }
 
 /*********	Functions for performance tools	************/
@@ -3874,8 +2089,9 @@
 	vm_address_t *zones_address_ref;
 	unsigned num_zones;
 	unsigned *num_zones_ref;
-	reader = reader_or_in_memory_fallback(reader, task);
-
+	if (!reader) {
+		reader = _malloc_default_reader;
+	}
 	// printf("Read malloc_zones at address %p should be %p\n", &malloc_zones, malloc_zones);
 	err = reader(task, remote_malloc_zones, sizeof(void *), (void **)&zones_address_ref);
 	// printf("Read malloc_zones[%p]=%p\n", remote_malloc_zones, *zones_address_ref);
@@ -4027,21 +2243,10 @@
 {
 	unsigned index = 0;
 	MALLOC_LOCK();
-#if CONFIG_EARLY_MALLOC
-	mfm_lock();
-#endif
 	while (index < malloc_num_zones) {
 		malloc_zone_t *zone = malloc_zones[index++];
 		zone->introspect->force_lock(zone);
 	}
-#if CONFIG_XZONE_MALLOC
-	// All of the xzone malloc zones share some global state, and that global
-	// state needs to be locked after all the zone specific state has been
-	// locked, to prevent deadlocks
-	if (initial_xzone_zone) {
-		xzm_force_lock_global_state(initial_xzone_zone);
-	}
-#endif // CONFIG_XZONE_MALLOC
 	if (callout) {
 		callout();
 	}
@@ -4050,11 +2255,6 @@
 static void
 _malloc_unlock_all(void (*callout)(void))
 {
-#if CONFIG_XZONE_MALLOC
-	if (initial_xzone_zone) {
-		xzm_force_unlock_global_state(initial_xzone_zone);
-	}
-#endif // CONFIG_XZONE_MALLOC
 	unsigned index = 0;
 	if (callout) {
 		callout();
@@ -4063,20 +2263,12 @@
 		malloc_zone_t *zone = malloc_zones[index++];
 		zone->introspect->force_unlock(zone);
 	}
-#if CONFIG_EARLY_MALLOC
-	mfm_unlock();
-#endif
 	MALLOC_UNLOCK();
 }
 
 static void
 _malloc_reinit_lock_all(void (*callout)(void))
 {
-#if CONFIG_XZONE_MALLOC
-	if (initial_xzone_zone) {
-		xzm_force_reinit_lock_global_state(initial_xzone_zone);
-	}
-#endif // CONFIG_XZONE_MALLOC
 	unsigned index = 0;
 	if (callout) {
 		callout();
@@ -4089,9 +2281,6 @@
 			zone->introspect->reinit_lock(zone);
 		}
 	}
-#if CONFIG_EARLY_MALLOC
-	mfm_reinit_lock();
-#endif
 	MALLOC_REINIT_LOCK();
 }
 
@@ -4117,9 +2306,11 @@
 _malloc_fork_child(void)
 {
 #if CONFIG_NANOZONE
-	if (_malloc_entropy_initialized) {
-		if (initial_nano_zone) {
-			nanov2_forked_zone((nanozonev2_t *)initial_nano_zone);
+	if (_malloc_initialize_pred) {
+		if (_malloc_engaged_nano == NANO_V2) {
+			nanov2_forked_zone((nanozonev2_t *)inline_malloc_default_zone());
+		} else if (_malloc_engaged_nano == NANO_V1) {
+			nano_forked_zone((nanozone_t *)inline_malloc_default_zone());
 		}
 	}
 #endif
@@ -4217,33 +2408,7 @@
 	}
 }
 
-void
-malloc_zero_on_free_disable(void)
-{
-	malloc_zero_policy = MALLOC_ZERO_NONE;
-}
-
-bool
-malloc_variant_is_debug_4test(void)
-{
-#ifdef DEBUG
-	return true;
-#else
-	return false;
-#endif
-}
-
-bool
-malloc_allows_internal_security_4test(void)
-{
-	return malloc_internal_security_policy;
-}
-
 /*****************	OBSOLETE ENTRY POINTS	********************/
-
-#ifndef PHASE_OUT_OLD_MALLOC
-#define PHASE_OUT_OLD_MALLOC 0
-#endif
 
 #if PHASE_OUT_OLD_MALLOC
 #error PHASE OUT THE FOLLOWING FUNCTIONS
@@ -4279,64 +2444,34 @@
 }
 
 #pragma mark -
-#pragma mark Malloc Thread Options
-
-malloc_thread_options_t
-malloc_get_thread_options(void)
-{
-	th_opts_t x = {.storage = _pthread_getspecific_direct(__TSD_MALLOC_THREAD_OPTIONS)};
-	return x.options;
-}
-
-void
-malloc_set_thread_options(malloc_thread_options_t opts)
-{
-	if (os_unlikely(opts.ReservedFlag)) {
-		malloc_zone_error(MALLOC_ABORT_ON_ERROR, true,
-				"malloc_zone_malloc_with_options: reserved TSD bit set\n");
-		__builtin_trap();
-	}
-
-	// Canonicalize options
-	if (opts.DisableExpensiveDebuggingOptions) {
-		opts.DisableProbabilisticGuardMalloc = true;
-		opts.DisableMallocStackLogging = true;
-	}
-
-	pgm_thread_set_disabled(opts.DisableProbabilisticGuardMalloc);
-
-	_malloc_set_thread_options(opts);
-}
-
-#pragma mark -
 #pragma mark Malloc Stack Logging
 
-static bool _malloc_register_stack_logger(bool at_startup);
 
 /* this is called from libsystem during initialization. */
-static void
-stack_logging_early_finished(const struct _malloc_late_init *funcs)
+void
+__stack_logging_early_finished(const struct _malloc_functions *funcs)
 {
 #if !TARGET_OS_DRIVERKIT
 	_dlopen = funcs->dlopen;
 	_dlsym = funcs->dlsym;
 #endif
-	if (funcs->version >= 2 && funcs->msl) {
-		msl = *funcs->msl;
-	}
 	const char **env = (const char**) *_NSGetEnviron();
 	for (const char **e = env; *e; e++) {
 		if (0==strncmp(*e, "MallocStackLogging", 18)) {
-			_malloc_register_stack_logger(true);
-			if (msl.set_flags_from_environment) {
-				// rdar://125495815 - re-fetch env, as it may have moved
-				msl.set_flags_from_environment((const char **)*_NSGetEnviron());
+			malloc_register_stack_logger();
+			void (*msl_set_flags_from_environment) (const char **env);
+			msl_set_flags_from_environment = _dlsym(msl.dylib, "msl_set_flags_from_environment");
+			if (msl_set_flags_from_environment) {
+				msl_set_flags_from_environment(env);
 			}
 			break;
 		}
 	}
-	if (msl.initialize) {
-		msl.initialize();
+	if (msl.dylib) {
+		void (*initialize) () = _dlsym(msl.dylib, "msl_initialize");
+		if (initialize) {
+			initialize();
+		}
 	}
 }
 
@@ -4346,67 +2481,45 @@
 static void
 register_msl_dylib(void *dylib)
 {
-#if TARGET_OS_DRIVERKIT
-	// rdar://153673319
-	if (!msl.copy_msl_lite_hooks) {
-		return;
-	}
-
-	set_msl_lite_hooks(msl.copy_msl_lite_hooks);
-#else
 	if (!dylib) {
 		return;
 	}
+	msl.dylib = dylib;
 	msl.handle_memory_event = _dlsym(dylib, "msl_handle_memory_event");
 	msl.stack_logging_locked = _dlsym(dylib, "msl_stack_logging_locked");
 	msl.fork_prepare = _dlsym(dylib, "msl_fork_prepare");
 	msl.fork_child = _dlsym(dylib, "msl_fork_child");
 	msl.fork_parent = _dlsym(dylib, "msl_fork_parent");
-	msl.turn_on_stack_logging = _dlsym(dylib, "msl_turn_on_stack_logging");
-	msl.turn_off_stack_logging = _dlsym(dylib, "msl_turn_off_stack_logging");
-	msl.set_flags_from_environment = _dlsym(dylib, "msl_set_flags_from_environment");
-	msl.initialize = _dlsym(dylib, "msl_initialize");
+	
+	// TODO delete these ones
+	msl.get_frames_for_address = _dlsym(dylib, "msl_get_frames_for_address");
+	msl.stackid_for_vm_region = _dlsym(dylib, "msl_stackid_for_vm_region");
+	msl.get_frames_for_stackid = _dlsym(dylib, "msl_get_frames_for_stackid");
+	msl.uniquing_table_read_stack = _dlsym(dylib, "msl_uniquing_table_read_stack");
 
 	void (*msl_copy_msl_lite_hooks) (struct _malloc_msl_lite_hooks_s *hooksp, size_t size);
 	msl_copy_msl_lite_hooks = _dlsym(dylib, "msl_copy_msl_lite_hooks");
 	if (msl_copy_msl_lite_hooks) {
 		set_msl_lite_hooks(msl_copy_msl_lite_hooks);
 	}
-#endif
 }
 
 MALLOC_EXPORT
 boolean_t
 malloc_register_stack_logger(void)
 {
-    return _malloc_register_stack_logger(false);
-}
-
-static bool
-_malloc_register_stack_logger(bool at_startup)
-{
-	void *dylib = NULL;
-	if (malloc_sanitizer_enabled && !at_startup) {
-		return false;
-	}
-#if !TARGET_OS_DRIVERKIT
-	if (msl.handle_memory_event != NULL) {
+	if (msl.dylib != NULL) {
 		return true;
 	}
-	if (_dlopen == NULL) {
-		return false;
-	}
-	dylib = _dlopen("/System/Library/PrivateFrameworks/MallocStackLogging.framework/MallocStackLogging", RTLD_GLOBAL);
+	void *dylib = _dlopen("/System/Library/PrivateFrameworks/Alternate/MallocStackLogging.framework/MallocStackLogging", RTLD_GLOBAL);
 	if (dylib == NULL) {
-		return false;	
-	}
-#endif
+		dylib = _dlopen("/System/Library/PrivateFrameworks/MallocStackLogging.framework/MallocStackLogging", RTLD_GLOBAL);
+	}
 	os_once(&_register_msl_dylib_pred, dylib, register_msl_dylib);
-	if (!msl.handle_memory_event) {
+	if (!msl.dylib) {
 		malloc_report(ASL_LEVEL_WARNING, "failed to load MallocStackLogging.framework\n");
-		return false;
-	}
-	return true;
+	}
+	return msl.dylib == dylib;
 }
 
 /* Symbolication.framework looks up this symbol by name inside libsystem_malloc.dylib. */
@@ -4428,19 +2541,237 @@
 turn_on_stack_logging(stack_logging_mode_type mode)
 {
 	malloc_register_stack_logger();
-	if (!msl.turn_on_stack_logging) {
+	if (!msl.dylib) {
 		return false;
 	}
-	return msl.turn_on_stack_logging(mode);
+	boolean_t (*msl_turn_on_stack_logging) (stack_logging_mode_type mode);
+	msl_turn_on_stack_logging = _dlsym(msl.dylib, "msl_turn_on_stack_logging");
+	if (!msl_turn_on_stack_logging) {
+		return false;
+	}
+	return msl_turn_on_stack_logging(mode);
 }
 
 MALLOC_EXPORT
 void turn_off_stack_logging(void)
 {
 	malloc_register_stack_logger();
-	if (msl.turn_off_stack_logging) {
-		msl.turn_off_stack_logging();
-	}
+	if (!msl.dylib) {
+		return;
+	}
+	void (*msl_turn_off_stack_logging) ();
+	msl_turn_off_stack_logging = _dlsym(msl.dylib, "msl_turn_off_stack_logging");
+	if (msl_turn_off_stack_logging) {
+		msl_turn_off_stack_logging();
+	}
+}
+
+kern_return_t
+__mach_stack_logging_start_reading(task_t task, vm_address_t shared_memory_address, boolean_t *uses_lite_mode)
+{
+	malloc_register_stack_logger();
+	if (!msl.dylib) {
+		return KERN_FAILURE;
+	}
+	kern_return_t (*f) (task_t task, vm_address_t shared_memory_address, boolean_t *uses_lite_mode);
+	f = _dlsym(msl.dylib, "msl_start_reading");
+	if (!f) {
+		return KERN_FAILURE;
+	}
+	return f(task, shared_memory_address, uses_lite_mode);
+}
+
+kern_return_t
+__mach_stack_logging_stop_reading(task_t task)
+{
+	malloc_register_stack_logger();
+	if (!msl.dylib) {
+		return KERN_FAILURE;
+	}
+	kern_return_t (*f) (task_t task);
+	f = _dlsym(msl.dylib, "msl_stop_reading");
+	if (!f) {
+		return KERN_FAILURE;
+	}
+	return f(task);
+}
+
+kern_return_t
+__mach_stack_logging_get_frames(task_t task,
+								mach_vm_address_t address,
+								mach_vm_address_t *stack_frames_buffer,
+								uint32_t max_stack_frames,
+								uint32_t *count)
+{
+	malloc_register_stack_logger();
+	if (!msl.get_frames_for_address) {
+		return KERN_FAILURE;
+	}
+	return msl.get_frames_for_address(task, address, stack_frames_buffer, max_stack_frames, count);
+}
+
+uint64_t
+__mach_stack_logging_stackid_for_vm_region(task_t task, mach_vm_address_t address)
+{
+	malloc_register_stack_logger();
+	if (!msl.stackid_for_vm_region) {
+		return -1ull;
+	}
+	return msl.stackid_for_vm_region(task, address);
+}
+
+
+kern_return_t
+__mach_stack_logging_frames_for_uniqued_stack(task_t task,
+											  uint64_t stack_identifier,
+											  mach_vm_address_t *stack_frames_buffer,
+											  uint32_t max_stack_frames,
+											  uint32_t *count)
+{
+	malloc_register_stack_logger();
+	if (!msl.get_frames_for_stackid) {
+		return KERN_FAILURE;
+	}
+	return msl.get_frames_for_stackid(task, stack_identifier, stack_frames_buffer, max_stack_frames, count, NULL);
+}
+
+kern_return_t
+__mach_stack_logging_get_frames_for_stackid(task_t task,
+											uint64_t stack_identifier,
+											mach_vm_address_t *stack_frames_buffer,
+											uint32_t max_stack_frames,
+											uint32_t *count,
+											bool *last_frame_is_threadid)
+{
+	malloc_register_stack_logger();
+	if (!msl.get_frames_for_stackid) {
+		return KERN_FAILURE;
+	}
+	return msl.get_frames_for_stackid(task, stack_identifier, stack_frames_buffer, max_stack_frames, count, last_frame_is_threadid);
+}
+
+kern_return_t
+__mach_stack_logging_uniquing_table_read_stack(struct backtrace_uniquing_table *uniquing_table,
+											   uint64_t stackid,
+											   mach_vm_address_t *out_frames_buffer,
+											   uint32_t *out_frames_count,
+											   uint32_t max_frames)
+{
+	malloc_register_stack_logger();
+	if (!msl.uniquing_table_read_stack) {
+		return KERN_FAILURE;
+	}
+	return msl.uniquing_table_read_stack(uniquing_table, stackid, out_frames_buffer, out_frames_count, max_frames);
+}
+
+kern_return_t
+__mach_stack_logging_enumerate_records(task_t task,
+									   mach_vm_address_t address,
+									   void enumerator(mach_stack_logging_record_t, void *),
+									   void *context)
+{
+	malloc_register_stack_logger();
+	kern_return_t (*f) (task_t task,
+						mach_vm_address_t address,
+						void enumerator(mach_stack_logging_record_t, void *),
+						void *context);
+	if (!msl.dylib) {
+		return KERN_FAILURE;
+	}
+	f = _dlsym(msl.dylib, "msl_disk_stack_logs_enumerate_from_task");
+	if (!f) {
+		return KERN_FAILURE;
+	}
+	return f(task, address, enumerator, context);
+}
+
+struct backtrace_uniquing_table *
+__mach_stack_logging_copy_uniquing_table(task_t task)
+{
+	malloc_register_stack_logger();
+	struct backtrace_uniquing_table * (*f) (task_t task);
+	if (!msl.dylib) {
+		return NULL;
+	}
+	f = _dlsym(msl.dylib, "msl_uniquing_table_copy_from_task");
+	if (!f) {
+		return NULL;
+	}
+	return f(task);
+}
+
+struct backtrace_uniquing_table *
+__mach_stack_logging_uniquing_table_copy_from_serialized(void *buffer, size_t size)
+{
+	malloc_register_stack_logger();
+	struct backtrace_uniquing_table * (*f) (void *buffer, size_t size);
+	if (!msl.dylib) {
+		return NULL;
+	}
+	f = _dlsym(msl.dylib, "msl_uniquing_table_copy_from_serialized");
+	if (!f) {
+		return NULL;
+	}
+	return f(buffer, size);
+}
+
+void
+__mach_stack_logging_uniquing_table_release(struct backtrace_uniquing_table *table)
+{
+	malloc_register_stack_logger();
+	if (!msl.dylib) {
+		return;
+	}
+	void (*f) (struct backtrace_uniquing_table *table);
+	f = _dlsym(msl.dylib, "msl_uniquing_table_release");
+	if (f) {
+		f(table);
+	}
+}
+
+void
+__mach_stack_logging_uniquing_table_retain(struct backtrace_uniquing_table *table)
+{
+	malloc_register_stack_logger();
+	if (!msl.dylib) {
+		return;
+	}
+	void (*f) (struct backtrace_uniquing_table *table);
+	f = _dlsym(msl.dylib, "msl_uniquing_table_retain");
+	if (f) {
+		f(table);
+	}
+}
+
+extern
+size_t
+__mach_stack_logging_uniquing_table_sizeof(struct backtrace_uniquing_table *table)
+{
+	malloc_register_stack_logger();
+	size_t (*f) (struct backtrace_uniquing_table *table);
+	f = _dlsym(msl.dylib, "msl_uniquing_table_retain");
+	return f(table);
+}
+
+void *
+__mach_stack_logging_uniquing_table_serialize(struct backtrace_uniquing_table *table, mach_vm_size_t *size)
+{
+	malloc_register_stack_logger();
+	if (!msl.dylib) {
+		return NULL;
+	}
+	void * (*f) (struct backtrace_uniquing_table *table, mach_vm_size_t *size);
+	f = _dlsym(msl.dylib, "msl_uniquing_table_serialize");
+	if (!f) {
+		return NULL;
+	}
+	return f(table, size);
+}
+
+kern_return_t
+__mach_stack_logging_set_file_path(task_t task, char* file_path)
+{
+	return KERN_SUCCESS;
 }
 
 /* WeChat references this, only god knows why.  This symbol does nothing. */