]> git.saurik.com Git - apple/xnu.git/blobdiff - osfmk/kern/zalloc.c
xnu-2050.22.13.tar.gz
[apple/xnu.git] / osfmk / kern / zalloc.c
index 9d1afa5d6e84a9e430c8c7218737481dd28c24d0..dc9ea000ca8eba965a977f601faf39c06dbbbd61 100644 (file)
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2000-2009 Apple Inc. All rights reserved.
+ * Copyright (c) 2000-2011 Apple Inc. All rights reserved.
  *
  * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
  * 
@@ -64,8 +64,6 @@
  */
 #include <zone_debug.h>
 #include <zone_alias_addr.h>
-#include <norma_vm.h>
-#include <mach_kdb.h>
 
 #include <mach/mach_types.h>
 #include <mach/vm_param.h>
@@ -74,6 +72,7 @@
 #include <mach/task_server.h>
 #include <mach/machine/vm_types.h>
 #include <mach_debug/zone_info.h>
+#include <mach/vm_map.h>
 
 #include <kern/kern_types.h>
 #include <kern/assert.h>
@@ -92,6 +91,8 @@
 #include <vm/vm_kern.h>
 #include <vm/vm_page.h>
 
+#include <pexpert/pexpert.h>
+
 #include <machine/machparam.h>
 
 #include <libkern/OSDebug.h>
 /* 
  * Zone Corruption Debugging
  *
- * We provide three methods to detect use of a zone element after it's been freed.  These
- * checks are enabled by specifying "-zc" and/or "-zp" in the boot-args:
+ * We perform three methods to detect use of a zone element after it's been freed. These
+ * checks are enabled for every N'th element (counted per-zone) by specifying
+ * "zp-factor=N" as a boot-arg. To turn this feature off, set "zp-factor=0" or "-no-zp".
+ *
+ * (1) Range-check the free-list "next" pointer for sanity.
+ * (2) Store the pointer in two different words, one at the beginning of the freed element
+ *     and one at the end, and compare them against each other when re-using the element,
+ *     to detect modifications.
+ * (3) Poison the freed memory by overwriting it with 0xdeadbeef, and check it when the
+ *     memory is being reused to make sure it is still poisoned.
+ *
+ * As a result, each element (that is large enough to hold this data inside) must be marked
+ * as either "ZP_POISONED" or "ZP_NOT_POISONED" in the first integer within the would-be
+ * poisoned segment after the first free-list pointer.
  *
- * (1) Range-check the free-list "next" ptr for sanity.
- * (2) Store the ptr in two different words, and compare them against
- *     each other when re-using the zone element, to detect modifications.
- * (3) poison the freed memory by overwriting it with 0xdeadbeef.
+ * Performance slowdown is inversely proportional to the frequency with which you check
+ * (as would be expected), with a 4-5% hit around N=1, down to ~0.3% at N=16 and just
+ * "noise" at N=32 and higher. You can expect to find a 100% reproducible
+ * bug in an average of N tries, with a standard deviation of about N, but you will probably
+ * want to set "zp-factor=1" or "-zp" if you are attempting to reproduce a known bug.
  *
- * The first two checks are fairly light weight and are enabled by specifying "-zc" 
- * in the boot-args.  If you want more aggressive checking for use-after-free bugs
- * and you don't mind the additional overhead, then turn on poisoning by adding
- * "-zp" to the boot-args in addition to "-zc".  If you specify -zp without -zc,
- * it still poisons the memory when it's freed, but doesn't check if the memory
- * has been altered later when it's reallocated.
+ *
+ * Zone corruption logging
+ *
+ * You can also track where corruptions come from by using the boot-arguments:
+ * "zlog=<zone name to log> -zc". Search for "Zone corruption logging" later in this
+ * document for more implementation and usage information.
+ */
+
+#define ZP_POISON       0xdeadbeef
+#define ZP_POISONED     0xfeedface
+#define ZP_NOT_POISONED 0xbaddecaf
+
+#if CONFIG_EMBEDDED
+       #define ZP_DEFAULT_SAMPLING_FACTOR 0
+#else /* CONFIG_EMBEDDED */
+       #define ZP_DEFAULT_SAMPLING_FACTOR 16
+#endif /* CONFIG_EMBEDDED */
+
+uint32_t       free_check_sample_factor = 0;           /* set by zp-factor=N boot arg */
+boolean_t      corruption_debug_flag    = FALSE;       /* enabled by "-zc" boot-arg */
+
+/* 
+ * Zone checking helper macro.
+ */
+#define is_kernel_data_addr(a) (!(a) || ((a) >= vm_min_kernel_address && !((a) & 0x3)))
+
+/*
+ * Frees the specified element, which is within the specified zone. If this
+ * element should be poisoned and its free list checker should be set, both are
+ * done here. These checks will only be enabled if the element size is at least
+ * large enough to hold two vm_offset_t's and one uint32_t (to enable both types
+ * of checks).
+ */
+static inline void
+free_to_zone(zone_t zone, void *elem) {
+       /* get the index of the first uint32_t beyond the 'next' pointer */
+       unsigned int i = sizeof(vm_offset_t) / sizeof(uint32_t);
+       
+       /* should we run checks on this piece of memory? */
+       if (free_check_sample_factor != 0 &&
+           zone->free_check_count++ % free_check_sample_factor == 0 &&
+           zone->elem_size >= (2 * sizeof(vm_offset_t) + sizeof(uint32_t))) {
+               zone->free_check_count = 1;
+               ((uint32_t *) elem)[i] = ZP_POISONED;
+               for (i++; i < zone->elem_size / sizeof(uint32_t); i++) {
+                       ((uint32_t *) elem)[i] = ZP_POISON;
+               }
+               ((vm_offset_t *) elem)[((zone->elem_size)/sizeof(vm_offset_t))-1] = zone->free_elements;
+       } else {
+               ((uint32_t *) elem)[i] = ZP_NOT_POISONED;
+       }
+       
+       /* maintain free list and decrement number of active objects in zone */
+       ((vm_offset_t *) elem)[0] = zone->free_elements;
+       zone->free_elements = (vm_offset_t) elem;
+       zone->count--;
+}
+
+/*
+ * Allocates an element from the specifed zone, storing its address in the
+ * return arg. This function will look for corruptions revealed through zone
+ * poisoning and free list checks.
  */
+static inline void
+alloc_from_zone(zone_t zone, void **ret) {
+       void *elem = (void *) zone->free_elements;
+       if (elem != NULL) {
+               /* get the index of the first uint32_t beyond the 'next' pointer */
+               unsigned int i = sizeof(vm_offset_t) / sizeof(uint32_t);
+               
+               /* first int in data section must be ZP_POISONED or ZP_NOT_POISONED */
+               if (((uint32_t *) elem)[i] == ZP_POISONED &&
+                   zone->elem_size >= (2 * sizeof(vm_offset_t) + sizeof(uint32_t))) {
+                       /* check the free list pointers */
+                       if (!is_kernel_data_addr(((vm_offset_t *) elem)[0]) ||
+                           ((vm_offset_t *) elem)[0] !=
+                           ((vm_offset_t *) elem)[(zone->elem_size/sizeof(vm_offset_t))-1]) {
+                               panic("a freed zone element has been modified in zone: %s",
+                                     zone->zone_name);
+                       }
+                       
+                       /* check for poisoning in free space */
+                       for (i++;
+                            i < zone->elem_size / sizeof(uint32_t) -
+                                sizeof(vm_offset_t) / sizeof(uint32_t);
+                            i++) {
+                               if (((uint32_t *) elem)[i] != ZP_POISON) {
+                                       panic("a freed zone element has been modified in zone: %s",
+                                             zone->zone_name);
+                               }
+                       }
+               } else if (((uint32_t *) elem)[i] != ZP_NOT_POISONED) {
+                       panic("a freed zone element has been modified in zone: %s",
+                             zone->zone_name);
+               }
+               
+               zone->count++;
+               zone->sum_count++;
+               zone->free_elements = ((vm_offset_t *) elem)[0];
+       }
+       *ret = elem;
+}
 
-boolean_t check_freed_element = FALSE;         /* enabled by -zc in boot-args */
-boolean_t zfree_clear = FALSE;                 /* enabled by -zp in boot-args */
 
 /*
  * Fake zones for things that want to report via zprint but are not actually zones.
@@ -131,26 +238,25 @@ struct fake_zone_info {
                      uint64_t *, int *, int *, int *);
 };
 
-static struct fake_zone_info fake_zones[] = {
+static const struct fake_zone_info fake_zones[] = {
        {
                .name = "kernel_stacks",
                .init = stack_fake_zone_init,
                .query = stack_fake_zone_info,
        },
-#if defined(__i386__) || defined (__x86_64__)
        {
                .name = "page_tables",
                .init = pt_fake_zone_init,
                .query = pt_fake_zone_info,
        },
-#endif /* i386 */
        {
                .name = "kalloc.large",
                .init = kalloc_fake_zone_init,
                .query = kalloc_fake_zone_info,
        },
 };
-unsigned int num_fake_zones = sizeof(fake_zones)/sizeof(fake_zones[0]);
+static const unsigned int num_fake_zones =
+       sizeof (fake_zones) / sizeof (fake_zones[0]);
 
 /*
  * Zone info options
@@ -159,61 +265,6 @@ boolean_t zinfo_per_task = FALSE;          /* enabled by -zinfop in boot-args */
 #define ZINFO_SLOTS 200                                /* for now */
 #define ZONES_MAX (ZINFO_SLOTS - num_fake_zones - 1)
 
-/* 
- * Allocation helper macros
- */
-#define is_kernel_data_addr(a) (!(a) || ((a) >= vm_min_kernel_address && !((a) & 0x3)))
-
-#define ADD_TO_ZONE(zone, element)                                     \
-MACRO_BEGIN                                                            \
-       if (zfree_clear)                                                \
-       {   unsigned int i;                                             \
-           for (i=0;                                                   \
-                i < zone->elem_size/sizeof(uint32_t);                  \
-                i++)                                                   \
-           ((uint32_t *)(element))[i] = 0xdeadbeef;                    \
-       }                                                               \
-       *((vm_offset_t *)(element)) = (zone)->free_elements;            \
-       if (check_freed_element) {                                      \
-               if ((zone)->elem_size >= (2 * sizeof(vm_offset_t)))     \
-                       ((vm_offset_t *)(element))[((zone)->elem_size/sizeof(vm_offset_t))-1] = \
-                               (zone)->free_elements;                  \
-       }                                                               \
-       (zone)->free_elements = (vm_offset_t) (element);                \
-       (zone)->count--;                                                \
-MACRO_END
-
-#define REMOVE_FROM_ZONE(zone, ret, type)                                      \
-MACRO_BEGIN                                                                    \
-       (ret) = (type) (zone)->free_elements;                                   \
-       if ((ret) != (type) 0) {                                                \
-               if (check_freed_element) {                                      \
-                       if (!is_kernel_data_addr(((vm_offset_t *)(ret))[0]) ||  \
-                           ((zone)->elem_size >= (2 * sizeof(vm_offset_t)) &&  \
-                           ((vm_offset_t *)(ret))[((zone)->elem_size/sizeof(vm_offset_t))-1] != \
-                           ((vm_offset_t *)(ret))[0]))                         \
-                               panic("a freed zone element has been modified");\
-                       if (zfree_clear) {                                      \
-                               unsigned int ii;                                \
-                               for (ii = sizeof(vm_offset_t) / sizeof(uint32_t); \
-                                    ii < (zone)->elem_size/sizeof(uint32_t) - sizeof(vm_offset_t) / sizeof(uint32_t); \
-                                        ii++)                                  \
-                                       if (((uint32_t *)(ret))[ii] != (uint32_t)0xdeadbeef) \
-                                               panic("a freed zone element has been modified");\
-                       }                                                       \
-               }                                                               \
-               (zone)->count++;                                                \
-               (zone)->sum_count++;                                            \
-               (zone)->free_elements = *((vm_offset_t *)(ret));                \
-       }                                                                       \
-MACRO_END
-
-#if    ZONE_DEBUG
-#define zone_debug_enabled(z) z->active_zones.next
-#define        ROUNDUP(x,y)            ((((x)+(y)-1)/(y))*(y))
-#define ZONE_DEBUG_OFFSET      ROUNDUP(sizeof(queue_chain_t),16) 
-#endif /* ZONE_DEBUG */
-
 /*
  * Support for garbage collection of unused zone pages
  *
@@ -255,7 +306,8 @@ void                zone_page_alloc(
                                vm_size_t       size);
 
 void           zone_page_free_element(
-                               zone_page_index_t       *free_page_list,
+                               zone_page_index_t       *free_page_head,
+                               zone_page_index_t       *free_page_tail,
                                vm_offset_t     addr,
                                vm_size_t       size);
 
@@ -277,12 +329,6 @@ void               zalloc_async(
 
 void           zone_display_zprint( void );
 
-#if    ZONE_DEBUG && MACH_KDB
-int            zone_count(
-                               zone_t          z,
-                               int             tail);
-#endif /* ZONE_DEBUG && MACH_KDB */
-
 vm_map_t       zone_map = VM_MAP_NULL;
 
 zone_t         zone_zone = ZONE_NULL;  /* the zone containing other zones */
@@ -298,16 +344,6 @@ zone_t             zinfo_zone = ZONE_NULL; /* zone of per-task zone info */
 vm_offset_t    zdata;
 vm_size_t      zdata_size;
 
-#define lock_zone(zone)                                        \
-MACRO_BEGIN                                            \
-       lck_mtx_lock_spin(&(zone)->lock);                       \
-MACRO_END
-
-#define unlock_zone(zone)                              \
-MACRO_BEGIN                                            \
-       lck_mtx_unlock(&(zone)->lock);                  \
-MACRO_END
-
 #define zone_wakeup(zone) thread_wakeup((event_t)(zone))
 #define zone_sleep(zone)                               \
        (void) lck_mtx_sleep(&(zone)->lock, LCK_SLEEP_SPIN, (event_t)(zone), THREAD_UNINT);
@@ -354,15 +390,14 @@ lck_grp_t       zone_lck_grp;
 lck_grp_attr_t  zone_lck_grp_attr;
 lck_mtx_ext_t   zone_lck_ext;
 
-
 #if    !ZONE_ALIAS_ADDR
 #define from_zone_map(addr, size) \
        ((vm_offset_t)(addr) >= zone_map_min_address && \
         ((vm_offset_t)(addr) + size -1) <  zone_map_max_address)
 #else
 #define from_zone_map(addr, size) \
-       ((vm_offset_t)(zone_virtual_addr((vm_map_address_t)addr)) >= zone_map_min_address && \
-        ((vm_offset_t)(zone_virtual_addr((vm_map_address_t)addr)) + size -1) <  zone_map_max_address)
+       ((vm_offset_t)(zone_virtual_addr((vm_map_address_t)(uintptr_t)addr)) >= zone_map_min_address && \
+        ((vm_offset_t)(zone_virtual_addr((vm_map_address_t)(uintptr_t)addr)) + size -1) <  zone_map_max_address)
 #endif
 
 /*
@@ -423,8 +458,9 @@ static char zone_name_to_log[MAX_ZONE_NAME] = "";   /* the zone name we're logging
  * records since going much larger than this tends to make the system unresponsive and unbootable on small
  * memory configurations.  The default value is 4000 records.
  */
+
 #if    defined(__LP64__)
-#define ZRECORDS_MAX           16000           /* Max records allowed in the log */
+#define ZRECORDS_MAX           128000          /* Max records allowed in the log */
 #else
 #define ZRECORDS_MAX           8000            /* Max records allowed in the log */
 #endif
@@ -518,7 +554,7 @@ extern boolean_t zlog_ready;
 
 /* 
  * The zone leak detector, abbreviated 'zleak', keeps track of a subset of the currently outstanding
- * allocations made by the zone allocator.  Every z_sample_factor allocations in each zone, we capture a
+ * allocations made by the zone allocator.  Every zleak_sample_factor allocations in each zone, we capture a
  * backtrace.  Every free, we examine the table and determine if the allocation was being tracked, 
  * and stop tracking it if it was being tracked.
  *
@@ -539,7 +575,7 @@ uint32_t    zleak_state = 0;                /* State of collection, as above */
 boolean_t      panic_include_ztrace    = FALSE;        /* Enable zleak logging on panic */
 vm_size_t      zleak_global_tracking_threshold;        /* Size of zone map at which to start collecting data */
 vm_size_t      zleak_per_zone_tracking_threshold;      /* Size a zone will have before we will collect data on it */
-unsigned int   z_sample_factor = 1000;                 /* Allocations per sample attempt */
+unsigned int   zleak_sample_factor     = 1000;         /* Allocations per sample attempt */
 
 /*
  * Counters for allocation statistics.
@@ -575,11 +611,8 @@ struct zallocation {
 };
 
 /* Size must be a power of two for the zhash to be able to just mask off bits instead of mod */
-#define ZLEAK_ALLOCATION_MAP_NUM       16384
-#define ZLEAK_TRACE_MAP_NUM            8192
-
-uint32_t zleak_alloc_buckets = ZLEAK_ALLOCATION_MAP_NUM;
-uint32_t zleak_trace_buckets = ZLEAK_TRACE_MAP_NUM;
+uint32_t zleak_alloc_buckets = CONFIG_ZLEAK_ALLOCATION_MAP_NUM;
+uint32_t zleak_trace_buckets = CONFIG_ZLEAK_TRACE_MAP_NUM;
 
 vm_size_t zleak_max_zonemap_size;
 
@@ -591,7 +624,7 @@ static struct ztrace*               ztraces;
 struct ztrace*                         top_ztrace;
 
 /* Lock to protect zallocations, ztraces, and top_ztrace from concurrent modification. */
-static lck_mtx_t                       zleak_lock;
+static lck_spin_t                      zleak_lock;
 static lck_attr_t                      zleak_lock_attr;
 static lck_grp_t                       zleak_lock_grp;
 static lck_grp_attr_t                  zleak_lock_grp_attr;
@@ -609,6 +642,15 @@ zleak_init(vm_size_t max_zonemap_size)
        zleak_global_tracking_threshold = max_zonemap_size / 2; 
        zleak_per_zone_tracking_threshold = zleak_global_tracking_threshold / 8;
 
+#if CONFIG_EMBEDDED
+       if (PE_parse_boot_argn("-zleakon", scratch_buf, sizeof(scratch_buf))) {
+               zleak_enable_flag = TRUE;
+               printf("zone leak detection enabled\n");
+       } else {
+               zleak_enable_flag = FALSE;
+               printf("zone leak detection disabled\n");
+       }
+#else /* CONFIG_EMBEDDED */
        /* -zleakoff (flag to disable zone leak monitor) */
        if (PE_parse_boot_argn("-zleakoff", scratch_buf, sizeof(scratch_buf))) {
                zleak_enable_flag = FALSE;
@@ -617,12 +659,13 @@ zleak_init(vm_size_t max_zonemap_size)
                zleak_enable_flag = TRUE;
                printf("zone leak detection enabled\n");
        }
+#endif /* CONFIG_EMBEDDED */
        
        /* zfactor=XXXX (override how often to sample the zone allocator) */
-       if (PE_parse_boot_argn("zfactor", &z_sample_factor, sizeof(z_sample_factor))) {
-               printf("Zone leak factor override:%u\n", z_sample_factor);
+       if (PE_parse_boot_argn("zfactor", &zleak_sample_factor, sizeof(zleak_sample_factor))) {
+               printf("Zone leak factor override:%u\n", zleak_sample_factor);
        }
-       
+
        /* zleak-allocs=XXXX (override number of buckets in zallocations) */
        if (PE_parse_boot_argn("zleak-allocs", &zleak_alloc_buckets, sizeof(zleak_alloc_buckets))) {
                printf("Zone leak alloc buckets override:%u\n", zleak_alloc_buckets);
@@ -645,7 +688,7 @@ zleak_init(vm_size_t max_zonemap_size)
        lck_grp_attr_setdefault(&zleak_lock_grp_attr);
        lck_grp_init(&zleak_lock_grp, "zleak_lock", &zleak_lock_grp_attr);
        lck_attr_setdefault(&zleak_lock_attr);
-       lck_mtx_init(&zleak_lock, &zleak_lock_grp, &zleak_lock_attr);
+       lck_spin_init(&zleak_lock, &zleak_lock_grp, &zleak_lock_attr);
        
        if (zleak_enable_flag) {
                zleak_state = ZLEAK_STATE_ENABLED;
@@ -656,7 +699,7 @@ zleak_init(vm_size_t max_zonemap_size)
 
 /*
  * Support for kern.zleak.active sysctl - a simplified
- * simplified version of the zleak_state variable.
+ * version of the zleak_state variable.
  */
 int
 get_zleak_state(void)
@@ -686,14 +729,14 @@ zleak_activate(void)
        }
 
        /* Indicate that we're doing the setup */
-       lck_mtx_lock_spin(&zleak_lock);
+       lck_spin_lock(&zleak_lock);
        if (zleak_state & (ZLEAK_STATE_ACTIVE | ZLEAK_STATE_ACTIVATING | ZLEAK_STATE_FAILED)) {
-               lck_mtx_unlock(&zleak_lock);
+               lck_spin_unlock(&zleak_lock);
                return KERN_SUCCESS;
        }
 
        zleak_state |= ZLEAK_STATE_ACTIVATING;
-       lck_mtx_unlock(&zleak_lock);
+       lck_spin_unlock(&zleak_lock);
 
        /* Allocate and zero tables */
        retval = kmem_alloc_kobject(kernel_map, (vm_offset_t*)&allocations_ptr, z_alloc_size);
@@ -724,10 +767,10 @@ zleak_activate(void)
         * the tables and setting the active flag, because the zfree()
         * path accesses the table without a lock if we're active.
         */
-       lck_mtx_lock_spin(&zleak_lock);
+       lck_spin_lock(&zleak_lock);
        zleak_state |= ZLEAK_STATE_ACTIVE;
        zleak_state &= ~ZLEAK_STATE_ACTIVATING;
-       lck_mtx_unlock(&zleak_lock);
+       lck_spin_unlock(&zleak_lock);
        
        return 0;
 
@@ -736,10 +779,10 @@ fail:
         * If we fail to allocate memory, don't further tax
         * the system by trying again.
         */
-       lck_mtx_lock_spin(&zleak_lock);
+       lck_spin_lock(&zleak_lock);
        zleak_state |= ZLEAK_STATE_FAILED;
        zleak_state &= ~ZLEAK_STATE_ACTIVATING;
-       lck_mtx_unlock(&zleak_lock);
+       lck_spin_unlock(&zleak_lock);
 
        if (allocations_ptr != NULL) {
                kmem_free(kernel_map, (vm_offset_t)allocations_ptr, z_alloc_size);
@@ -776,7 +819,7 @@ zleak_log(uintptr_t* bt,
                  vm_size_t allocation_size) 
 {
        /* Quit if there's someone else modifying the hash tables */
-       if (!lck_mtx_try_lock_spin(&zleak_lock)) {
+       if (!lck_spin_try_lock(&zleak_lock)) {
                z_total_conflicts++;
                return FALSE;
        }
@@ -796,7 +839,7 @@ zleak_log(uintptr_t* bt,
        if (allocation->za_element != (uintptr_t) 0 && trace_index == allocation->za_trace_index) {
                z_alloc_collisions++;
                
-               lck_mtx_unlock(&zleak_lock);
+               lck_spin_unlock(&zleak_lock);
                return TRUE;
        }
        
@@ -812,7 +855,7 @@ zleak_log(uintptr_t* bt,
                trace->zt_collisions++;
                z_trace_collisions++;
                
-               lck_mtx_unlock(&zleak_lock);
+               lck_spin_unlock(&zleak_lock);
                return TRUE;
        } else if (trace->zt_size > 0) {
                /* Same trace, already added, so increment refcount */
@@ -858,7 +901,7 @@ zleak_log(uintptr_t* bt,
        if (top_ztrace->zt_size < trace->zt_size)
                top_ztrace = trace;
        
-       lck_mtx_unlock(&zleak_lock);
+       lck_spin_unlock(&zleak_lock);
        return TRUE;
 }
 
@@ -881,7 +924,7 @@ zleak_free(uintptr_t addr,
        
        if (allocation->za_element == addr && allocation->za_trace_index < zleak_trace_buckets) {
                /* if the allocation was the one, grab the lock, check again, then delete it */
-               lck_mtx_lock_spin(&zleak_lock);
+               lck_spin_lock(&zleak_lock);
                
                if (allocation->za_element == addr && allocation->za_trace_index < zleak_trace_buckets) {
                        struct ztrace *trace;
@@ -902,7 +945,7 @@ zleak_free(uintptr_t addr,
                        /* A NULL element means the allocation bucket is unused */
                        allocation->za_element = 0;
                }
-               lck_mtx_unlock(&zleak_lock);
+               lck_spin_unlock(&zleak_lock);
        }
 }
 
@@ -918,21 +961,23 @@ zleak_free(uintptr_t addr,
  * It's fast because it does no checking to make sure there isn't bad data.
  * Since it's only called from threads that we're going to keep executing,
  * if there's bad data we were going to die eventually.
- * This seems to work for x86 and X86_64.
- * ARMTODO: Test it on ARM, I think it will work but I can't test it.  If it works, remove the ifdef.
  * If this function is inlined, it doesn't record the frame of the function it's inside.
  * (because there's no stack frame!)
  */
+
 uint32_t
 fastbacktrace(uintptr_t* bt, uint32_t max_frames)
 {
-#if defined(__x86_64__) || defined(__i386__)
        uintptr_t* frameptr = NULL, *frameptr_next = NULL;
        uintptr_t retaddr = 0;
        uint32_t frame_index = 0, frames = 0;
        uintptr_t kstackb, kstackt;
+       thread_t cthread = current_thread();
 
-       kstackb = current_thread()->kernel_stack;
+       if (__improbable(cthread == NULL))
+               return 0;
+
+       kstackb = cthread->kernel_stack;
        kstackt = kstackb + kernel_stack_size;
        /* Load stack frame pointer (EBP on x86) into frameptr */
        frameptr = __builtin_frame_address(0);
@@ -965,9 +1010,6 @@ fastbacktrace(uintptr_t* bt, uint32_t max_frames)
                bt[frame_index++] = 0;
 
        return frames;
-#else
-       return OSBacktrace((void*)bt, max_frames);
-#endif
 }
 
 /* "Thomas Wang's 32/64 bit mix functions."  http://www.concentric.net/~Ttwang/tech/inthash.htm */
@@ -1001,8 +1043,8 @@ hashbacktrace(uintptr_t* bt, uint32_t depth, uint32_t max_size)
        uintptr_t hash = 0;
        uintptr_t mask = max_size - 1;
 
-       while (--depth) {
-               hash += bt[depth];
+       while (depth) {
+               hash += bt[--depth];
        }
 
        hash = hash_mix(hash) & mask;
@@ -1053,6 +1095,7 @@ zinit(
                zdata_size -= sizeof(*z);
        } else
                z = (zone_t) zalloc(zone_zone);
+
        if (z == ZONE_NULL)
                return(ZONE_NULL);
 
@@ -1128,6 +1171,8 @@ use_this_allocation:
        z->noencrypt = FALSE;
        z->no_callout = FALSE;
        z->async_prio_refill = FALSE;
+       z->gzalloc_exempt = FALSE;
+       z->alignment_required = FALSE;
        z->prio_refill_watermark = 0;
        z->zone_replenish_thread = NULL;
 #if CONFIG_ZLEAKS
@@ -1165,8 +1210,7 @@ use_this_allocation:
        /*
         * Check if we should be logging this zone.  If so, remember the zone pointer.
         */
-
-        if (log_this_zone(z->zone_name, zone_name_to_log)) {
+       if (log_this_zone(z->zone_name, zone_name_to_log)) {
                zone_of_interest = z;
        }
 
@@ -1178,7 +1222,6 @@ use_this_allocation:
         * later on some other zone.  So note we may be allocating a buffer to log a zone other than the one being initialized
         * right now.
         */
-
        if (zone_of_interest != NULL && zrecords == NULL && zlog_ready) {
                if (kmem_alloc(kernel_map, (vm_offset_t *)&zrecords, log_records * sizeof(struct zrecord)) == KERN_SUCCESS) {
 
@@ -1195,7 +1238,9 @@ use_this_allocation:
                        zone_of_interest = NULL;
                }
        }
-
+#if    CONFIG_GZALLOC  
+       gzalloc_zone_init(z);
+#endif
        return(z);
 }
 unsigned       zone_replenish_loops, zone_replenish_wakeups, zone_replenish_wakeups_initiated;
@@ -1306,10 +1351,10 @@ zcram(
 
        lock_zone(zone);
        while (size >= elem_size) {
-               ADD_TO_ZONE(zone, newmem);
+               free_to_zone(zone, (void *) newmem);
                if (from_zm)
                        zone_page_alloc(newmem, elem_size);
-               zone->count++;  /* compensate for ADD_TO_ZONE */
+               zone->count++;  /* compensate for free_to_zone */
                size -= elem_size;
                newmem += elem_size;
                zone->cur_size += elem_size;
@@ -1325,6 +1370,9 @@ zcram(
 void
 zone_steal_memory(void)
 {
+#if    CONFIG_GZALLOC
+       gzalloc_configure();
+#endif
        /* Request enough early memory to get to the pmap zone */
        zdata_size = 12 * sizeof(struct zone);
        zdata = (vm_offset_t)pmap_steal_memory(round_page(zdata_size));
@@ -1375,35 +1423,30 @@ zone_bootstrap(void)
 {
        char temp_buf[16];
 
-#if 6094439
-       /* enable zone checks by default, to try and catch offenders... */
-#if 0
-       /* 7968354: turn "-zc" back off */
-       check_freed_element = TRUE;
-       /* 7995202: turn "-zp" back off */
-       zfree_clear = TRUE;
-#endif
-       
-       /* ... but allow them to be turned off explicitely */
-       if (PE_parse_boot_argn("-no_zc", temp_buf, sizeof (temp_buf))) {
-               check_freed_element = FALSE;
-       }
-       if (PE_parse_boot_argn("-no_zp", temp_buf, sizeof (temp_buf))) {
-               zfree_clear = FALSE;
+       if (PE_parse_boot_argn("-zinfop", temp_buf, sizeof(temp_buf))) {
+               zinfo_per_task = TRUE;
        }
-#endif
 
-       /* see if we want freed zone element checking and/or poisoning */
-       if (PE_parse_boot_argn("-zc", temp_buf, sizeof (temp_buf))) {
-               check_freed_element = TRUE;
+       /* do we want corruption-style debugging with zlog? */
+       if (PE_parse_boot_argn("-zc", temp_buf, sizeof(temp_buf))) {
+               corruption_debug_flag = TRUE;
        }
+       
+       /* Set up zone poisoning */
 
-       if (PE_parse_boot_argn("-zp", temp_buf, sizeof (temp_buf))) {
-               zfree_clear = TRUE;
+       free_check_sample_factor = ZP_DEFAULT_SAMPLING_FACTOR;
+
+       /* support for old zone poisoning boot-args */
+       if (PE_parse_boot_argn("-zp", temp_buf, sizeof(temp_buf))) {
+               free_check_sample_factor = 1;
+       }
+       if (PE_parse_boot_argn("-no-zp", temp_buf, sizeof(temp_buf))) {
+               free_check_sample_factor = 0;
        }
 
-       if (PE_parse_boot_argn("-zinfop", temp_buf, sizeof (temp_buf))) {
-               zinfo_per_task = TRUE;
+       /* zp-factor=XXXX (override how often to poison freed zone elements) */
+       if (PE_parse_boot_argn("zp-factor", &free_check_sample_factor, sizeof(free_check_sample_factor))) {
+               printf("Zone poisoning factor override:%u\n", free_check_sample_factor);
        }
 
        /*
@@ -1498,6 +1541,9 @@ zone_init(
        if (retval != KERN_SUCCESS)
                panic("zone_init: kmem_suballoc failed");
        zone_max = zone_min + round_page(max_zonemap_size);
+#if    CONFIG_GZALLOC
+       gzalloc_init(max_zonemap_size);
+#endif
        /*
         * Setup garbage collection information:
         */
@@ -1608,19 +1654,26 @@ zalloc_canblock(
        register zone_t zone,
        boolean_t canblock)
 {
-       vm_offset_t     addr;
-       kern_return_t retval;
+       vm_offset_t     addr = 0;
+       kern_return_t   retval;
        uintptr_t       zbt[MAX_ZTRACE_DEPTH];  /* used in zone leak logging and zone leak detection */
        int             numsaved = 0;
-       int                     i;
+       int             i;
        boolean_t       zone_replenish_wakeup = FALSE;
+       boolean_t       did_gzalloc;
 
+       did_gzalloc = FALSE;
 #if CONFIG_ZLEAKS
        uint32_t        zleak_tracedepth = 0;  /* log this allocation if nonzero */
 #endif /* CONFIG_ZLEAKS */
 
        assert(zone != ZONE_NULL);
-       
+
+#if    CONFIG_GZALLOC
+       addr = gzalloc_alloc(zone, canblock);
+       did_gzalloc = (addr != 0);
+#endif
+
        lock_zone(zone);
 
        /*
@@ -1632,10 +1685,10 @@ zalloc_canblock(
        
 #if CONFIG_ZLEAKS
        /* 
-        * Zone leak detection: capture a backtrace every z_sample_factor
+        * Zone leak detection: capture a backtrace every zleak_sample_factor
         * allocations in this zone. 
         */
-       if (zone->zleak_on && (zone->zleak_capture++ % z_sample_factor == 0)) {
+       if (zone->zleak_on && (zone->zleak_capture++ % zleak_sample_factor == 0)) {
                zone->zleak_capture = 1;
                
                /* Avoid backtracing twice if zone logging is on */
@@ -1646,10 +1699,12 @@ zalloc_canblock(
        }
 #endif /* CONFIG_ZLEAKS */
 
-       REMOVE_FROM_ZONE(zone, addr, vm_offset_t);
+       if (__probable(addr == 0))
+               alloc_from_zone(zone, (void **) &addr);
 
        if (zone->async_prio_refill &&
-       ((zone->cur_size - (zone->count * zone->elem_size)) < (zone->prio_refill_watermark * zone->elem_size))) {
+           ((zone->cur_size - (zone->count * zone->elem_size)) <
+           (zone->prio_refill_watermark * zone->elem_size))) {
                zone_replenish_wakeup = TRUE;
                zone_replenish_wakeups_initiated++;
        }
@@ -1698,6 +1753,11 @@ zalloc_canblock(
                                } else {
                                        unlock_zone(zone);
 
+                                       panic_include_zprint = TRUE;
+#if CONFIG_ZLEAKS
+                                       if (zleak_state & ZLEAK_STATE_ACTIVE)
+                                               panic_include_ztrace = TRUE;
+#endif /* CONFIG_ZLEAKS */
                                        panic("zalloc: zone \"%s\" empty.", zone->zone_name);
                                }
                        }
@@ -1749,7 +1809,7 @@ zalloc_canblock(
                                        retry++;
                                        
                                        if (retry == 2) {
-                                               zone_gc();
+                                               zone_gc(TRUE);
                                                printf("zalloc did gc\n");
                                                zone_display_zprint();
                                        }
@@ -1775,7 +1835,7 @@ zalloc_canblock(
                                zone->waiting = FALSE;
                                zone_wakeup(zone);
                        }
-                       REMOVE_FROM_ZONE(zone, addr, vm_offset_t);
+                       alloc_from_zone(zone, (void **) &addr);
                        if (addr == 0 &&
                                retval == KERN_RESOURCE_SHORTAGE) {
                                unlock_zone(zone);
@@ -1785,7 +1845,7 @@ zalloc_canblock(
                        }
                }
                if (addr == 0)
-                       REMOVE_FROM_ZONE(zone, addr, vm_offset_t);
+                       alloc_from_zone(zone, (void **) &addr);
        }
 
 #if CONFIG_ZLEAKS
@@ -1796,7 +1856,7 @@ zalloc_canblock(
                /* Sampling can fail if another sample is happening at the same time in a different zone. */
                if (!zleak_log(zbt, addr, zleak_tracedepth, zone->elem_size)) {
                        /* If it failed, roll back the counter so we sample the next allocation instead. */
-                       zone->zleak_capture = z_sample_factor;
+                       zone->zleak_capture = zleak_sample_factor;
                }
        }
 #endif /* CONFIG_ZLEAKS */                     
@@ -1815,16 +1875,16 @@ zalloc_canblock(
                 * depending on whether we're looking for the source of a zone leak or a zone corruption.  When looking
                 * for a leak, we want to log as many allocations as possible in order to clearly identify the leaker
                 * among all the records.  So we look for an unused slot in the log and fill that in before overwriting
-                * an old entry.  When looking for a corrution however, it's better to have a chronological log of all
+                * an old entry.  When looking for a corruption however, it's better to have a chronological log of all
                 * the allocations and frees done in the zone so that the history of operations for a specific zone 
                 * element can be inspected.  So in this case, we treat the log as a circular buffer and overwrite the
                 * oldest entry whenever a new one needs to be added.
                 *
-                * The check_freed_element flag tells us what style of logging to do.  It's set if we're supposed to be
+                * The corruption_debug_flag flag tells us what style of logging to do.  It's set if we're supposed to be
                 * doing corruption style logging (indicated via -zc in the boot-args).
                 */
 
-               if (!check_freed_element && zrecords[zcurrent].z_element && zrecorded < log_records) {
+               if (!corruption_debug_flag && zrecords[zcurrent].z_element && zrecorded < log_records) {
 
                        /*
                         * If we get here, we're doing leak style logging and there's still some unused entries in
@@ -1832,8 +1892,8 @@ zalloc_canblock(
                         * starting at zcurrent and wrap-around if we reach the end of the buffer.  If the buffer
                         * is already full, we just fall through and overwrite the element indexed by zcurrent.
                         */
-       
-                      for (i = zcurrent; i < log_records; i++) {
+
+                       for (i = zcurrent; i < log_records; i++) {
                                if (zrecords[i].z_element == NULL) {
                                        zcurrent = i;
                                        goto empty_slot;
@@ -1877,11 +1937,11 @@ empty_slot:
                unlock_zone(zone);
                thread_call_enter(&zone->call_async_alloc);
                lock_zone(zone);
-               REMOVE_FROM_ZONE(zone, addr, vm_offset_t);
+               alloc_from_zone(zone, (void **) &addr);
        }
 
 #if    ZONE_DEBUG
-       if (addr && zone_debug_enabled(zone)) {
+       if (!did_gzalloc && addr && zone_debug_enabled(zone)) {
                enqueue_tail(&zone->active_zones, (queue_entry_t)addr);
                addr += ZONE_DEBUG_OFFSET;
        }
@@ -1904,14 +1964,15 @@ empty_slot:
                thread_t thr = current_thread();
                task_t task;
                zinfo_usage_t zinfo;
+               vm_size_t sz = zone->elem_size;
 
                if (zone->caller_acct)
-                       thr->tkm_private.alloc += zone->elem_size;
+                       ledger_credit(thr->t_ledger, task_ledgers.tkm_private, sz);
                else
-                       thr->tkm_shared.alloc += zone->elem_size;
+                       ledger_credit(thr->t_ledger, task_ledgers.tkm_shared, sz);
 
                if ((task = thr->task) != NULL && (zinfo = task->tkm_zinfo) != NULL)
-                       OSAddAtomic64(zone->elem_size, (int64_t *)&zinfo[zone->index].alloc);
+                       OSAddAtomic64(sz, (int64_t *)&zinfo[zone->index].alloc);
        }
        return((void *)addr);
 }
@@ -1945,7 +2006,6 @@ zalloc_async(
        unlock_zone(((zone_t)p0));
 }
 
-
 /*
  *     zget returns an element from the specified zone
  *     and immediately returns nothing if there is nothing there.
@@ -1961,7 +2021,7 @@ void *
 zget(
        register zone_t zone)
 {
-       register vm_offset_t    addr;
+       vm_offset_t     addr;
        
 #if CONFIG_ZLEAKS
        uintptr_t       zbt[MAX_ZTRACE_DEPTH];          /* used for zone leak detection */
@@ -1977,13 +2037,13 @@ zget(
        /*
         * Zone leak detection: capture a backtrace
         */
-       if (zone->zleak_on && (zone->zleak_capture++ % z_sample_factor == 0)) {
+       if (zone->zleak_on && (zone->zleak_capture++ % zleak_sample_factor == 0)) {
                zone->zleak_capture = 1;
                zleak_tracedepth = fastbacktrace(zbt, MAX_ZTRACE_DEPTH);
        }
 #endif /* CONFIG_ZLEAKS */
 
-       REMOVE_FROM_ZONE(zone, addr, vm_offset_t);
+       alloc_from_zone(zone, (void **) &addr);
 #if    ZONE_DEBUG
        if (addr && zone_debug_enabled(zone)) {
                enqueue_tail(&zone->active_zones, (queue_entry_t)addr);
@@ -1999,7 +2059,7 @@ zget(
                /* Sampling can fail if another sample is happening at the same time in a different zone. */
                if (!zleak_log(zbt, addr, zleak_tracedepth, zone->elem_size)) {
                        /* If it failed, roll back the counter so we sample the next allocation instead. */
-                       zone->zleak_capture = z_sample_factor;
+                       zone->zleak_capture = zleak_sample_factor;
                }
        }
        
@@ -2026,8 +2086,9 @@ zfree(
        void            *addr)
 {
        vm_offset_t     elem = (vm_offset_t) addr;
-       void            *zbt[MAX_ZTRACE_DEPTH];                 /* only used if zone logging is enabled via boot-args */
+       void            *zbt[MAX_ZTRACE_DEPTH]; /* only used if zone logging is enabled via boot-args */
        int             numsaved = 0;
+       boolean_t       gzfreed = FALSE;
 
        assert(zone != ZONE_NULL);
 
@@ -2047,10 +2108,14 @@ zfree(
                panic("zfree: freeing to zone_zone breaks zone_gc!");
 #endif
 
+#if    CONFIG_GZALLOC  
+       gzfreed = gzalloc_free(zone, addr);
+#endif
+
        TRACE_MACHLEAKS(ZFREE_CODE, ZFREE_CODE_2, zone->elem_size, (uintptr_t)addr);
 
-       if (zone->collectable && !zone->allows_foreign &&
-           !from_zone_map(elem, zone->elem_size)) {
+       if (__improbable(!gzfreed && zone->collectable && !zone->allows_foreign &&
+               !from_zone_map(elem, zone->elem_size))) {
 #if MACH_ASSERT
                panic("zfree: non-allocated memory in collectable zone!");
 #endif
@@ -2069,7 +2134,7 @@ zfree(
        if (DO_LOGGING(zone)) {
                int  i;
 
-               if (check_freed_element) {
+               if (corruption_debug_flag) {
 
                        /*
                         * We're logging to catch a corruption.  Add a record of this zfree operation
@@ -2116,7 +2181,7 @@ zfree(
 
 
 #if    ZONE_DEBUG
-       if (zone_debug_enabled(zone)) {
+       if (!gzfreed && zone_debug_enabled(zone)) {
                queue_t tmp_elem;
 
                elem -= ZONE_DEBUG_OFFSET;
@@ -2145,7 +2210,10 @@ zfree(
                        if (!pmap_kernel_va(this) || this == elem)
                                panic("zfree");
        }
-       ADD_TO_ZONE(zone, elem);
+
+       if (__probable(!gzfreed))
+               free_to_zone(zone, (void *) elem);
+
 #if MACH_ASSERT
        if (zone->count < 0)
                panic("zfree: count < 0!");
@@ -2178,14 +2246,15 @@ zfree(
                thread_t thr = current_thread();
                task_t task;
                zinfo_usage_t zinfo;
+               vm_size_t sz = zone->elem_size;
 
                if (zone->caller_acct)
-                       thr->tkm_private.free += zone->elem_size;
+                       ledger_debit(thr->t_ledger, task_ledgers.tkm_private, sz);
                else
-                       thr->tkm_shared.free += zone->elem_size;
+                       ledger_debit(thr->t_ledger, task_ledgers.tkm_shared, sz);
+
                if ((task = thr->task) != NULL && (zinfo = task->tkm_zinfo) != NULL)
-                       OSAddAtomic64(zone->elem_size,
-                                     (int64_t *)&zinfo[zone->index].free);
+                       OSAddAtomic64(sz, (int64_t *)&zinfo[zone->index].free);
        }
 }
 
@@ -2224,11 +2293,24 @@ zone_change(
                case Z_NOCALLOUT:
                        zone->no_callout = value;
                        break;
-#if MACH_ASSERT
+               case Z_GZALLOC_EXEMPT:
+                       zone->gzalloc_exempt = value;
+#if    CONFIG_GZALLOC
+                       gzalloc_reconfigure(zone);
+#endif
+                       break;
+               case Z_ALIGNMENT_REQUIRED:
+                       zone->alignment_required = value;
+#if    ZONE_DEBUG                      
+                       zone_debug_disable(zone);
+#endif
+#if    CONFIG_GZALLOC
+                       gzalloc_reconfigure(zone);
+#endif
+                       break;
                default:
                        panic("Zone_change: Wrong Item Type!");
                        /* break; */
-#endif
        }
 }
 
@@ -2253,24 +2335,6 @@ zone_free_count(zone_t zone)
        return(free_count);
 }
 
-/*
- *     zprealloc preallocates wired memory, exanding the specified
- *      zone to the specified size
- */
-void
-zprealloc(
-       zone_t  zone,
-       vm_size_t size)
-{
-        vm_offset_t addr;
-
-       if (size != 0) {
-               if (kmem_alloc_kobject(zone_map, &addr, size) != KERN_SUCCESS)
-                 panic("zprealloc");
-               zcram(zone, addr, size);
-       }
-}
-
 /*
  *  Zone garbage collection subroutines
  */
@@ -2419,7 +2483,8 @@ zone_page_alloc(
 
 void
 zone_page_free_element(
-       zone_page_index_t       *free_page_list,
+       zone_page_index_t       *free_page_head,
+       zone_page_index_t       *free_page_tail,
        vm_offset_t     addr,
        vm_size_t       size)
 {
@@ -2444,6 +2509,7 @@ zone_page_free_element(
                        --zp->collect_count;
                if (--zp->alloc_count == 0) {
                        vm_address_t        free_page_address;
+                       vm_address_t        prev_free_page_address;
 
                        zp->alloc_count  = ZONE_PAGE_UNUSED;
                        zp->collect_count = 0;
@@ -2454,8 +2520,16 @@ zone_page_free_element(
                         * storage for a page freelist
                         */
                        free_page_address = zone_map_min_address + PAGE_SIZE * ((vm_size_t)i);
-                       *(zone_page_index_t *)free_page_address = *free_page_list;
-                       *free_page_list = i;
+                       *(zone_page_index_t *)free_page_address = ZONE_PAGE_INDEX_INVALID;
+
+                       if (*free_page_head == ZONE_PAGE_INDEX_INVALID) {
+                               *free_page_head = i;
+                               *free_page_tail = i;
+                       } else {
+                               prev_free_page_address = zone_map_min_address + PAGE_SIZE * ((vm_size_t)(*free_page_tail));
+                               *(zone_page_index_t *)prev_free_page_address = i;
+                               *free_page_tail = i;
+                       }
                }
        }
 }
@@ -2471,14 +2545,12 @@ struct zone_free_element {
  * Add a linked list of pages starting at base back into the zone
  * free list. Tail points to the last element on the list.
  */
-
 #define ADD_LIST_TO_ZONE(zone, base, tail)                             \
 MACRO_BEGIN                                                            \
        (tail)->next = (void *)((zone)->free_elements);                 \
-       if (check_freed_element) {                                      \
-               if ((zone)->elem_size >= (2 * sizeof(vm_offset_t)))     \
-                       ((vm_offset_t *)(tail))[((zone)->elem_size/sizeof(vm_offset_t))-1] = \
-                                        (zone)->free_elements;         \
+       if ((zone)->elem_size >= (2 * sizeof(vm_offset_t) + sizeof(uint32_t))) {        \
+               ((vm_offset_t *)(tail))[((zone)->elem_size/sizeof(vm_offset_t))-1] =    \
+                       (zone)->free_elements;                          \
        }                                                               \
        (zone)->free_elements = (unsigned long)(base);                  \
 MACRO_END
@@ -2486,15 +2558,13 @@ MACRO_END
 /*
  * Add an element to the chain pointed to by prev.
  */
-
-#define ADD_ELEMENT(zone, prev, elem)                                          \
+#define ADD_ELEMENT(zone, prev, elem)                                  \
 MACRO_BEGIN                                                            \
        (prev)->next = (elem);                                          \
-       if (check_freed_element) {                                      \
-               if ((zone)->elem_size >= (2 * sizeof(vm_offset_t)))     \
-                       ((vm_offset_t *)(prev))[((zone)->elem_size/sizeof(vm_offset_t))-1] = \
-                                       (vm_offset_t)(elem);            \
-        }                                                              \
+       if ((zone)->elem_size >= (2 * sizeof(vm_offset_t) + sizeof(uint32_t))) {        \
+               ((vm_offset_t *)(prev))[((zone)->elem_size/sizeof(vm_offset_t))-1] =    \
+                       (vm_offset_t)(elem);                            \
+       }                                                               \
 MACRO_END
 
 struct {
@@ -2513,12 +2583,14 @@ struct {
  *     begins to run out of memory.
  */
 void
-zone_gc(void)
+zone_gc(boolean_t all_zones)
 {
        unsigned int    max_zones;
        zone_t                  z;
        unsigned int    i;
        zone_page_index_t zone_free_page_head;
+       zone_page_index_t zone_free_page_tail;
+       thread_t        mythread = current_thread();
 
        lck_mtx_lock(&zone_gc_lock);
 
@@ -2527,6 +2599,14 @@ zone_gc(void)
        z = first_zone;
        simple_unlock(&all_zones_lock);
 
+
+       /*
+        * it's ok to allow eager kernel preemption while
+        * while holding a zone lock since it's taken
+        * as a spin lock (which prevents preemption)
+        */
+       thread_set_eager_preempt(mythread);
+
 #if MACH_ASSERT
        for (i = 0; i < zone_pages; i++) {
                struct zone_page_table_entry    *zp;
@@ -2536,24 +2616,26 @@ zone_gc(void)
        }
 #endif /* MACH_ASSERT */
 
-       zone_free_page_head = ZONE_PAGE_INDEX_INVALID;
-
        for (i = 0; i < max_zones; i++, z = z->next_zone) {
-               unsigned int                            n, m;
-               vm_size_t                                       elt_size, size_freed;
+               unsigned int                    n, m;
+               vm_size_t                       elt_size, size_freed;
                struct zone_free_element        *elt, *base_elt, *base_prev, *prev, *scan, *keep, *tail;
+               int                             kmem_frees = 0;
 
                assert(z != ZONE_NULL);
 
                if (!z->collectable)
                        continue;
 
+               if (all_zones == FALSE && z->elem_size < PAGE_SIZE)
+                       continue;
+
                lock_zone(z);
 
                elt_size = z->elem_size;
 
                /*
-                * Do a quick feasability check before we scan the zone: 
+                * Do a quick feasibility check before we scan the zone: 
                 * skip unless there is likelihood of getting pages back
                 * (i.e we need a whole allocation block's worth of free
                 * elements before we can garbage collect) and
@@ -2589,6 +2671,11 @@ zone_gc(void)
                prev = (void *)&scan;
                elt = scan;
                n = 0; tail = keep = NULL;
+
+               zone_free_page_head = ZONE_PAGE_INDEX_INVALID;
+               zone_free_page_tail = ZONE_PAGE_INDEX_INVALID;
+
+
                while (elt != NULL) {
                        if (from_zone_map(elt, elt_size)) {
                                zone_page_collect((vm_offset_t)elt, elt_size);
@@ -2676,6 +2763,7 @@ zone_gc(void)
                size_freed = 0;
                elt = scan;
                n = 0; tail = keep = NULL;
+
                while (elt != NULL) {
                        if (zone_page_collectable((vm_offset_t)elt, elt_size)) {
                                struct zone_free_element *next_elt = elt->next;
@@ -2688,8 +2776,7 @@ zone_gc(void)
                                 * list of free-able pages. So store elt->next because
                                 * "elt" may be scribbled over.
                                 */
-                               zone_page_free_element(&zone_free_page_head,
-                                                                               (vm_offset_t)elt, elt_size);
+                               zone_page_free_element(&zone_free_page_head, &zone_free_page_tail, (vm_offset_t)elt, elt_size);
 
                                elt = next_elt;
 
@@ -2760,29 +2847,67 @@ zone_gc(void)
                        zone_wakeup(z);
                }
                unlock_zone(z);
-       }
 
-       /*
-        * Reclaim the pages we are freeing.
-        */
 
-       while (zone_free_page_head != ZONE_PAGE_INDEX_INVALID) {
-               zone_page_index_t       zind = zone_free_page_head;
-               vm_address_t            free_page_address;
-#if    ZONE_ALIAS_ADDR
-               z = (zone_t)zone_virtual_addr((vm_map_address_t)z);
-#endif
-               /* Use the first word of the page about to be freed to find the next free page */
-               free_page_address = zone_map_min_address + PAGE_SIZE * ((vm_size_t)zind);
-               zone_free_page_head = *(zone_page_index_t *)free_page_address;
+               if (zone_free_page_head == ZONE_PAGE_INDEX_INVALID)
+                       continue;
+
+               /*
+                * we don't want to allow eager kernel preemption while holding the
+                * various locks taken in the kmem_free path of execution
+                */
+               thread_clear_eager_preempt(mythread);
+
+               /*
+                * Reclaim the pages we are freeing.
+                */
+               while (zone_free_page_head != ZONE_PAGE_INDEX_INVALID) {
+                       zone_page_index_t       zind = zone_free_page_head;
+                       vm_address_t            free_page_address;
+                       int                     page_count;
+
+                       /*
+                        * Use the first word of the page about to be freed to find the next free page
+                        */
+                       free_page_address = zone_map_min_address + PAGE_SIZE * ((vm_size_t)zind);
+                       zone_free_page_head = *(zone_page_index_t *)free_page_address;
+
+                       page_count = 1;
+
+                       while (zone_free_page_head != ZONE_PAGE_INDEX_INVALID) {
+                               zone_page_index_t       next_zind = zone_free_page_head;
+                               vm_address_t            next_free_page_address;
+
+                               next_free_page_address = zone_map_min_address + PAGE_SIZE * ((vm_size_t)next_zind);
+
+                               if (next_free_page_address == (free_page_address - PAGE_SIZE)) {
+                                       free_page_address = next_free_page_address;
+                               } else if (next_free_page_address != (free_page_address + (PAGE_SIZE * page_count)))
+                                       break;
+
+                               zone_free_page_head = *(zone_page_index_t *)next_free_page_address;
+                               page_count++;
+                       }
+                       kmem_free(zone_map, free_page_address, page_count * PAGE_SIZE);
+
+                       zgc_stats.pgs_freed += page_count;
 
-               kmem_free(zone_map, free_page_address, PAGE_SIZE);
-               ++zgc_stats.pgs_freed;
+                       if (++kmem_frees == 32) {
+                               thread_yield_internal(1);
+                               kmem_frees = 0;
+                       }
+               }
+               thread_set_eager_preempt(mythread);
        }
+       thread_clear_eager_preempt(mythread);
 
        lck_mtx_unlock(&zone_gc_lock);
+
 }
 
+extern vm_offset_t kmapoff_kaddr;
+extern unsigned int kmapoff_pgcnt;
+
 /*
  *     consider_zone_gc:
  *
@@ -2792,14 +2917,29 @@ zone_gc(void)
 void
 consider_zone_gc(boolean_t force)
 {
+       boolean_t all_zones = FALSE;
+
+       if (kmapoff_kaddr != 0) {
+               /*
+                * One-time reclaim of kernel_map resources we allocated in
+                * early boot.
+                */
+               (void) vm_deallocate(kernel_map,
+                   kmapoff_kaddr, kmapoff_pgcnt * PAGE_SIZE_64);
+               kmapoff_kaddr = 0;
+       }
 
        if (zone_gc_allowed &&
            (zone_gc_allowed_by_time_throttle ||
             zone_gc_forced ||
             force)) {
+               if (zone_gc_allowed_by_time_throttle == TRUE) {
+                       zone_gc_allowed_by_time_throttle = FALSE;
+                       all_zones = TRUE;
+               }
                zone_gc_forced = FALSE;
-               zone_gc_allowed_by_time_throttle = FALSE; /* reset periodically */
-               zone_gc();
+
+               zone_gc(all_zones);
        }
 }
 
@@ -2814,6 +2954,8 @@ compute_zone_gc_throttle(void *arg __unused)
 }
 
 
+#if CONFIG_TASK_ZONE_INFO
+
 kern_return_t
 task_zone_info(
        task_t                  task,
@@ -2972,9 +3114,24 @@ task_zone_info(
        return KERN_SUCCESS;
 }
 
+#else  /* CONFIG_TASK_ZONE_INFO */
+
+kern_return_t
+task_zone_info(
+       __unused task_t         task,
+       __unused mach_zone_name_array_t *namesp,
+       __unused mach_msg_type_number_t *namesCntp,
+       __unused task_zone_info_array_t *infop,
+       __unused mach_msg_type_number_t *infoCntp)
+{
+       return KERN_FAILURE;
+}
+
+#endif /* CONFIG_TASK_ZONE_INFO */
+
 kern_return_t
 mach_zone_info(
-       host_t                  host,
+       host_priv_t             host,
        mach_zone_name_array_t  *namesp,
        mach_msg_type_number_t  *namesCntp,
        mach_zone_info_array_t  *infop,
@@ -2998,8 +3155,10 @@ mach_zone_info(
 
        if (host == HOST_NULL)
                return KERN_INVALID_HOST;
-
-       num_fake_zones = sizeof fake_zones / sizeof fake_zones[0];
+#if CONFIG_DEBUGGER_FOR_ZONE_INFO
+       if (!PE_i_can_has_debugger(NULL))
+               return KERN_INVALID_HOST;
+#endif
 
        /*
         *      We assume that zones aren't freed once allocated.
@@ -3122,7 +3281,7 @@ mach_zone_info(
  */
 kern_return_t
 host_zone_info(
-       host_t                  host,
+       host_priv_t             host,
        zone_name_array_t       *namesp,
        mach_msg_type_number_t  *namesCntp,
        zone_info_array_t       *infop,
@@ -3146,6 +3305,10 @@ host_zone_info(
 
        if (host == HOST_NULL)
                return KERN_INVALID_HOST;
+#if CONFIG_DEBUGGER_FOR_ZONE_INFO
+       if (!PE_i_can_has_debugger(NULL))
+               return KERN_INVALID_HOST;
+#endif
 
 #if defined(__LP64__)
        if (!thread_is_64bit(current_thread()))
@@ -3155,8 +3318,6 @@ host_zone_info(
                return KERN_NOT_SUPPORTED;
 #endif
 
-       num_fake_zones = sizeof fake_zones / sizeof fake_zones[0];
-
        /*
         *      We assume that zones aren't freed once allocated.
         *      We won't pick up any zones that are allocated later.
@@ -3260,6 +3421,19 @@ host_zone_info(
        return KERN_SUCCESS;
 }
 
+kern_return_t
+mach_zone_force_gc(
+       host_t host)
+{
+
+       if (host == HOST_NULL)
+               return KERN_INVALID_HOST;
+
+       consider_zone_gc(TRUE);
+
+       return (KERN_SUCCESS);
+}
+
 extern unsigned int stack_total;
 extern unsigned long long stack_allocs;
 
@@ -3297,279 +3471,10 @@ void zone_display_zprint()
        printf("Kalloc.Large:\t%lu\n",(uintptr_t)kalloc_large_total);
 }
 
-
-
-#if    MACH_KDB
-#include <ddb/db_command.h>
-#include <ddb/db_output.h>
-#include <kern/kern_print.h>
-
-const char *zone_labels =
-"ENTRY       COUNT   TOT_SZ   MAX_SZ ELT_SZ ALLOC_SZ NAME";
-
-/* Forwards */
-void   db_print_zone(
-               zone_t          addr);
-
-#if    ZONE_DEBUG
-void   db_zone_check_active(
-               zone_t          zone);
-void   db_zone_print_active(
-               zone_t          zone);
-#endif /* ZONE_DEBUG */
-void   db_zone_print_free(
-               zone_t          zone);
-void
-db_print_zone(
-       zone_t          addr)
-{
-       struct zone zcopy;
-
-       zcopy = *addr;
-
-       db_printf("%8x %8x %8x %8x %6x %8x %s ",
-                 addr, zcopy.count, zcopy.cur_size,
-                 zcopy.max_size, zcopy.elem_size,
-                 zcopy.alloc_size, zcopy.zone_name);
-       if (zcopy.exhaustible)
-               db_printf("H");
-       if (zcopy.collectable)
-               db_printf("C");
-       if (zcopy.expandable)
-               db_printf("X");
-       if (zcopy.caller_acct)
-               db_printf("A");
-       db_printf("\n");
-}
-
-/*ARGSUSED*/
-void
-db_show_one_zone(db_expr_t addr, boolean_t have_addr,
-                __unused db_expr_t count, __unused char *modif)
-{
-       struct zone *z = (zone_t)((char *)0 + addr);
-
-       if (z == ZONE_NULL || !have_addr){
-               db_error("No Zone\n");
-               /*NOTREACHED*/
-       }
-
-       db_printf("%s\n", zone_labels);
-       db_print_zone(z);
-}
-
-/*ARGSUSED*/
-void
-db_show_all_zones(__unused db_expr_t addr, boolean_t have_addr, db_expr_t count,
-                 __unused char *modif)
-{
-       zone_t          z;
-       unsigned total = 0;
-
-       /*
-        * Don't risk hanging by unconditionally locking,
-        * risk of incoherent data is small (zones aren't freed).
-        */
-       have_addr = simple_lock_try(&all_zones_lock);
-       count = num_zones;
-       z = first_zone;
-       if (have_addr) {
-               simple_unlock(&all_zones_lock);
-       }
-
-       db_printf("%s\n", zone_labels);
-       for (  ; count > 0; count--) {
-               if (!z) {
-                       db_error("Mangled Zone List\n");
-                       /*NOTREACHED*/
-               }
-               db_print_zone(z);
-               total += z->cur_size,
-
-               have_addr = simple_lock_try(&all_zones_lock);
-               z = z->next_zone;
-               if (have_addr) {
-                       simple_unlock(&all_zones_lock);
-               }
-       }
-       db_printf("\nTotal              %8x", total);
-       db_printf("\n\nzone_gc() has reclaimed %d pages\n", zgc_stats.pgs_freed);
-}
-
-#if    ZONE_DEBUG
-void
-db_zone_check_active(
-       zone_t  zone)
-{
-       int count = 0;
-       queue_t tmp_elem;
-
-       if (!zone_debug_enabled(zone) || !zone_check)
-               return;
-       tmp_elem = queue_first(&zone->active_zones);
-       while (count < zone->count) {
-               count++;
-               if (tmp_elem == 0) {
-                       printf("unexpected zero element, zone=%p, count=%d\n",
-                               zone, count);
-                       assert(FALSE);
-                       break;
-               }
-               if (queue_end(tmp_elem, &zone->active_zones)) {
-                       printf("unexpected queue_end, zone=%p, count=%d\n",
-                               zone, count);
-                       assert(FALSE);
-                       break;
-               }
-               tmp_elem = queue_next(tmp_elem);
-       }
-       if (!queue_end(tmp_elem, &zone->active_zones)) {
-               printf("not at queue_end, zone=%p, tmp_elem=%p\n",
-                       zone, tmp_elem);
-               assert(FALSE);
-       }
-}
-
-void
-db_zone_print_active(
-       zone_t  zone)
-{
-       int count = 0;
-       queue_t tmp_elem;
-
-       if (!zone_debug_enabled(zone)) {
-               printf("zone %p debug not enabled\n", zone);
-               return;
-       }
-       if (!zone_check) {
-               printf("zone_check FALSE\n");
-               return;
-       }
-
-       printf("zone %p, active elements %d\n", zone, zone->count);
-       printf("active list:\n");
-       tmp_elem = queue_first(&zone->active_zones);
-       while (count < zone->count) {
-               printf("  %p", tmp_elem);
-               count++;
-               if ((count % 6) == 0)
-                       printf("\n");
-               if (tmp_elem == 0) {
-                       printf("\nunexpected zero element, count=%d\n", count);
-                       break;
-               }
-               if (queue_end(tmp_elem, &zone->active_zones)) {
-                       printf("\nunexpected queue_end, count=%d\n", count);
-                       break;
-               }
-               tmp_elem = queue_next(tmp_elem);
-       }
-       if (!queue_end(tmp_elem, &zone->active_zones))
-               printf("\nnot at queue_end, tmp_elem=%p\n", tmp_elem);
-       else
-               printf("\n");
-}
-#endif /* ZONE_DEBUG */
-
-void
-db_zone_print_free(
-       zone_t  zone)
-{
-       int count = 0;
-       int freecount;
-       vm_offset_t elem;
-
-       freecount = zone_free_count(zone);
-       printf("zone %p, free elements %d\n", zone, freecount);
-       printf("free list:\n");
-       elem = zone->free_elements;
-       while (count < freecount) {
-               printf("  0x%x", elem);
-               count++;
-               if ((count % 6) == 0)
-                       printf("\n");
-               if (elem == 0) {
-                       printf("\nunexpected zero element, count=%d\n", count);
-                       break;
-               }
-               elem = *((vm_offset_t *)elem);
-       }
-       if (elem != 0)
-               printf("\nnot at end of free list, elem=0x%x\n", elem);
-       else
-               printf("\n");
-}
-
-#endif /* MACH_KDB */
-
-
 #if    ZONE_DEBUG
 
 /* should we care about locks here ? */
 
-#if    MACH_KDB
-void *
-next_element(
-       zone_t          z,
-       void            *prev)
-{
-       char            *elt = (char *)prev;
-
-       if (!zone_debug_enabled(z))
-               return(NULL);
-       elt -= ZONE_DEBUG_OFFSET;
-       elt = (char *) queue_next((queue_t) elt);
-       if ((queue_t) elt == &z->active_zones)
-               return(NULL);
-       elt += ZONE_DEBUG_OFFSET;
-       return(elt);
-}
-
-void *
-first_element(
-       zone_t          z)
-{
-       char            *elt;
-
-       if (!zone_debug_enabled(z))
-               return(NULL);
-       if (queue_empty(&z->active_zones))
-               return(NULL);
-       elt = (char *)queue_first(&z->active_zones);
-       elt += ZONE_DEBUG_OFFSET;
-       return(elt);
-}
-
-/*
- * Second arg controls how many zone elements are printed:
- *   0 => none
- *   n, n < 0 => all
- *   n, n > 0 => last n on active list
- */
-int
-zone_count(
-       zone_t          z,
-       int             tail)
-{
-       void            *elt;
-       int             count = 0;
-       boolean_t       print = (tail != 0);
-
-       if (tail < 0)
-               tail = z->count;
-       if (z->count < tail)
-               tail = 0;
-       tail = z->count - tail;
-       for (elt = first_element(z); elt; elt = next_element(z, elt)) {
-               if (print && tail <= count)
-                       db_printf("%8x\n", elt);
-               count++;
-       }
-       assert(count == z->count);
-       return(count);
-}
-#endif /* MACH_KDB */
-
 #define zone_in_use(z)         ( z->count || z->free_elements )
 
 void