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--- libmalloc/libmalloc-283/src/nanov2_malloc.c
+++ libmalloc/libmalloc-374.100.5/src/nanov2_malloc.c
@@ -53,7 +53,7 @@
MALLOC_NOEXPORT extern size_t nanov2_pressure_relief(nanozonev2_t *nanozone, size_t goal);
#if OS_VARIANT_RESOLVED
-MALLOC_NOEXPORT extern boolean_t nanov2_allocate_new_region(nanozonev2_t *nanozone);
+MALLOC_NOEXPORT extern nanov2_arena_t *nanov2_allocate_new_region(nanozonev2_t *nanozone);
#endif // OS_VARIANT_RESOLVED
#pragma mark -
@@ -239,13 +239,14 @@
// Given a block metadata pointer, returns whether the block is active (that is,
// it is being used for allocations, it has allocations that have not been freed,
-// or is waiting to be madvised).
+// or is waiting to be madvised and is not a guard block).
static MALLOC_ALWAYS_INLINE MALLOC_INLINE boolean_t
nanov2_is_block_active(nanov2_block_meta_t block_meta)
{
return block_meta.next_slot != SLOT_NULL
&& block_meta.next_slot != SLOT_MADVISING
- && block_meta.next_slot != SLOT_MADVISED;
+ && block_meta.next_slot != SLOT_MADVISED
+ && block_meta.next_slot != SLOT_GUARD;
}
#if OS_VARIANT_RESOLVED
@@ -312,7 +313,6 @@
return (void *)(((uintptr_t)ptr) & NANOV2_ARENA_ADDRESS_MASK);
}
-#if OS_VARIANT_RESOLVED
// Given a pointer that is assumed to be in the Nano zone, returns the address
// of its containing region. Works for both real and logical pointers.
static MALLOC_ALWAYS_INLINE MALLOC_INLINE nanov2_region_t *
@@ -320,7 +320,6 @@
{
return (nanov2_region_t *)(((uintptr_t)ptr) & NANOV2_REGION_ADDRESS_MASK);
}
-#endif // OS_VARIANT_RESOLVED
// Given a pointer that is assumed to be in the Nano zone, returns the real
// address of its metadata block. Works for both real and logical pointers.
@@ -394,15 +393,40 @@
return (nanov2_arena_t *)region;
}
+#if OS_VARIANT_RESOLVED
+// Given an atomically-observed current_region_next_arena pointer, returns
+// whether or not it's a usable arena or a limit arena (indicating exhaustion of
+// the current region).
+static MALLOC_ALWAYS_INLINE MALLOC_INLINE bool
+nanov2_current_region_next_arena_is_limit(
+ nanov2_arena_t *current_region_next_arena)
+{
+ // The first arena of a region is never stored in current_region_next_arena,
+ // so a value at the beginning of a region must be a limit arena.
+ return current_region_next_arena == (nanov2_arena_t *)(
+ nanov2_region_address_for_ptr(current_region_next_arena));
+}
+#endif // OS_VARIANT_RESOLVED
+
+// Given an atomically-observed current_region_next_arena pointer, returns the
+// base of the current region at the time of the observation.
+static MALLOC_ALWAYS_INLINE MALLOC_INLINE nanov2_region_t *
+nanov2_current_region_base(nanov2_arena_t *current_region_next_arena)
+{
+ return nanov2_region_address_for_ptr(
+ (void *)(((uintptr_t)current_region_next_arena) - 1));
+}
+
// Given a region pointer, returns a pointer to the arena after the last
// active arena in the region.
static MALLOC_ALWAYS_INLINE MALLOC_INLINE nanov2_arena_t *
-nanov2_limit_arena_for_region(nanozonev2_t *nanozone, nanov2_region_t *region)
+nanov2_limit_arena_for_region(nanozonev2_t __unused *nanozone,
+ nanov2_region_t *region, nanov2_arena_t *current_region_next_arena)
{
// The first arena is colocated with the region itself.
nanov2_arena_t *limit_arena;
- if (region == nanozone->current_region_base) {
- limit_arena = nanozone->current_region_next_arena;
+ if (region == nanov2_current_region_base(current_region_next_arena)) {
+ limit_arena = current_region_next_arena;
} else {
limit_arena = nanov2_first_arena_for_region(region + 1);
}
@@ -423,14 +447,23 @@
#if OS_VARIANT_RESOLVED
// Given a pointer to a region, returns a pointer to the region that follows it,
-// or NULL if there isn't one.
+// or NULL if there isn't one. We may observe linkage to a new region that
+// hasn't yet actually been installed into current_region_next_arena; ignore the
+// linkage in this case.
static MALLOC_ALWAYS_INLINE MALLOC_INLINE nanov2_region_t *
-nanov2_next_region_for_region(nanozonev2_t *nanozone, nanov2_region_t *region)
+nanov2_next_region_for_region(nanozonev2_t *nanozone, nanov2_region_t *region,
+ nanov2_arena_t *current_region_next_arena)
{
nanov2_region_linkage_t *linkage =
nanov2_region_linkage_for_region(nanozone, region);
- int offset = linkage->next_region_offset;
- return offset ? region + offset : NULL;
+ int offset = os_atomic_load(&linkage->next_region_offset, relaxed);
+ if (!offset) {
+ return NULL;
+ }
+
+ nanov2_region_t *next_region = region + offset;
+ return (nanov2_arena_t *)next_region < current_region_next_arena ?
+ next_region : NULL;
}
#endif // OS_VARIANT_RESOLVED
@@ -440,14 +473,21 @@
// for another process.
static MALLOC_ALWAYS_INLINE MALLOC_INLINE nanov2_region_t *
nanov2_next_region_for_region_offset(nanozonev2_t *nanozone,
- nanov2_region_t *region, off_t region_offset)
-{
- nanov2_region_linkage_t *linkage =
- nanov2_region_linkage_for_region(nanozone, region);
- nanov2_region_linkage_t *mapped_linkage = (nanov2_region_linkage_t *)
- ((uintptr_t)linkage + region_offset);
- int offset = mapped_linkage->next_region_offset;
- return offset ? region + offset : NULL;
+ nanov2_region_t *region, off_t region_offset,
+ nanov2_arena_t *current_region_next_arena)
+{
+ nanov2_region_linkage_t *linkage =
+ nanov2_region_linkage_for_region(nanozone, region);
+ nanov2_region_linkage_t *mapped_linkage = (nanov2_region_linkage_t *)(
+ ((uintptr_t)linkage + region_offset));
+ int offset = os_atomic_load(&mapped_linkage->next_region_offset, relaxed);
+ if (!offset) {
+ return NULL;
+ }
+
+ nanov2_region_t *next_region = region + offset;
+ return (nanov2_arena_t *)next_region < current_region_next_arena ?
+ next_region : NULL;
}
#endif // OS_VARIANT_NOTRESOLVED
@@ -595,15 +635,15 @@
#if CONFIG_NANO_USES_HYPER_SHIFT
if (os_likely(nano_common_max_magazines_is_ncpu)) {
// Default case is max magazines == physical number of CPUs, which
- // must be > _os_cpu_number() >> hyper_shift, so the modulo
+ // must be > _malloc_cpu_number() >> hyper_shift, so the modulo
// operation is not required.
- return _os_cpu_number() >> hyper_shift;
+ return _malloc_cpu_number() >> hyper_shift;
}
#else // CONFIG_NANO_USES_HYPER_SHIFT
if (os_likely(nano_common_max_magazines_is_ncpu)) {
// Default case is max magazines == logical number of CPUs, which
- // must be > _os_cpu_number() so the modulo operation is not required.
- return _os_cpu_number();
+ // must be > _malloc_cpu_number() so the modulo operation is not required.
+ return _malloc_cpu_number();
}
#endif // CONFIG_NANO_USES_HYPER_SHIFT
@@ -613,11 +653,62 @@
#endif // CONFIG_NANO_USES_HYPER_SHIFT
if (os_likely(_os_cpu_number_override == -1)) {
- return (_os_cpu_number() >> shift) % nano_common_max_magazines;
+ return (_malloc_cpu_number() >> shift) % nano_common_max_magazines;
}
return (_os_cpu_number_override >> shift) % nano_common_max_magazines;
}
#endif // OS_VARIANT_RESOLVED
+
+#pragma mark -
+#pragma mark Guard Blocks
+
+// Converts a given block (specified by absolute block number) in an arena into
+// a guard block. The block will be marked as in-use so that it is not available
+// for allocations and its permissions are set to PROT_READ. Note that
+// PROT_READ is used instead of PROT_NONE because the latter breaks the
+// enumerator, which tries to map the whole region and fails if there are
+// PROT_NONE pages in the range. We can't fix that in the allocator because the
+// code that does the mapping is part of the sampling tools and is simply
+// invoked as a callback from the enumerator.
+static MALLOC_ALWAYS_INLINE MALLOC_INLINE void
+nanov2_create_guard_block(nanozonev2_t *nanozone, nanov2_arena_t *arena,
+ nanov2_block_index_t block_index) {
+ // Mark the block as in-use in the meta data
+ static nanov2_block_meta_t in_use_block = {
+ .in_use = 1,
+ .next_slot = SLOT_GUARD
+ };
+ nanov2_meta_index_t block_meta_index =
+ nanov2_block_index_to_meta_index(block_index);
+ nanov2_arena_metablock_t *block_metap = nanov2_metablock_address_for_ptr(
+ nanozone, arena);
+ block_metap->arena_block_meta[block_meta_index] = in_use_block;
+ void *block_ptr = &arena->blocks[block_index];
+
+ // Apply PROT_NONE to the block itself.
+ kern_return_t err = mprotect(block_ptr, NANOV2_BLOCK_SIZE, PROT_READ);
+ if (err != KERN_SUCCESS) {
+ malloc_report(ASL_LEVEL_ERR, "Failed to create guard block at %p (%d)\n",
+ block_ptr, err);
+ }
+}
+
+// Creates the guard blocks for an arena, if required. The guard blocks are
+// the first and last physical blocks in the arena that are not the metadata
+// block.
+static MALLOC_ALWAYS_INLINE MALLOC_INLINE void
+nanov2_init_guard_blocks(nanozonev2_t *nanozone, nanov2_arena_t *arena)
+{
+ if (nanozone->debug_flags & MALLOC_ALL_GUARD_PAGE_FLAGS) {
+ // Use the first and last blocks in the arena as guard regions,
+ // avoiding the metadata block.
+ nanov2_meta_index_t meta_index = nanov2_metablock_meta_index(nanozone);
+ nanov2_create_guard_block(nanozone, arena, meta_index == 0 ? 1 : 0);
+ nanov2_create_guard_block(nanozone, arena,
+ meta_index == NANOV2_BLOCKS_PER_ARENA - 1 ?
+ NANOV2_BLOCKS_PER_ARENA - 2 : NANOV2_BLOCKS_PER_ARENA - 1);
+ }
+}
#pragma mark -
#pragma mark Allocator Initialization
@@ -1191,9 +1282,12 @@
// until we reach our goal.
nanov2_region_t *region = nanozone->first_region_base;
nanov2_meta_index_t metablock_meta_index = nanov2_metablock_meta_index(nanozone);
+ nanov2_arena_t *current_region_next_arena = os_atomic_load(
+ &nanozone->current_region_next_arena, acquire);
while (region) {
nanov2_arena_t *arena = nanov2_first_arena_for_region(region);
- nanov2_arena_t *arena_after_region = nanov2_limit_arena_for_region(nanozone, region);
+ nanov2_arena_t *arena_after_region = nanov2_limit_arena_for_region(
+ nanozone, region, current_region_next_arena);
while (arena < arena_after_region) {
// Scan all of the blocks in the arena, skipping the metadata block.
nanov2_arena_metablock_t *meta_blockp =
@@ -1225,7 +1319,8 @@
}
arena++;
}
- region = nanov2_next_region_for_region(nanozone, region);
+ region = nanov2_next_region_for_region(nanozone, region,
+ current_region_next_arena);
}
done:
@@ -1282,7 +1377,7 @@
if (kr) {
return kr;
}
- boolean_t self_zone = (nanozonev2_t *)zone_address == nanozone;
+ boolean_t self_zone = mach_task_is_self(task) && (nanozonev2_t *)zone_address == nanozone;
memcpy(&zone_copy, nanozone, sizeof(zone_copy));
nanozone = &zone_copy;
nanov2_meta_index_t metablock_meta_index = nanov2_metablock_meta_index(nanozone);
@@ -1290,6 +1385,8 @@
// Process the zone one region at a time. Report each in-use block as a
// pointer range and each in-use slot as a pointer.
nanov2_region_t *region = nanozone->first_region_base;
+ nanov2_arena_t *current_region_next_arena = os_atomic_load(
+ &nanozone->current_region_next_arena, acquire);
while (region) {
mach_vm_address_t vm_addr = (mach_vm_address_t)NULL;
kern_return_t kr = reader(task, (vm_address_t)region, NANOV2_REGION_SIZE, (void **)&vm_addr);
@@ -1301,7 +1398,8 @@
// and its mapped address in this process.
mach_vm_offset_t ptr_offset = (mach_vm_address_t)region - vm_addr;
nanov2_arena_t *arena = nanov2_first_arena_for_region(region);
- nanov2_arena_t *limit_arena = nanov2_limit_arena_for_region(nanozone, region);
+ nanov2_arena_t *limit_arena = nanov2_limit_arena_for_region(nanozone, region,
+ current_region_next_arena);
vm_range_t ptr_range;
while (arena < limit_arena) {
// Find the metadata block and process every entry, apart from the
@@ -1415,7 +1513,8 @@
nanov2_region_linkage_t *mapped_region_linkagep =
NANOV2_ZONE_PTR_TO_MAPPED_PTR(nanov2_region_linkage_t *,
region_linkagep, ptr_offset);
- int offset = mapped_region_linkagep->next_region_offset;
+ int offset = os_atomic_load(&mapped_region_linkagep->next_region_offset,
+ relaxed);
region = offset ? region + offset : NULL;
}
return 0;
@@ -1434,7 +1533,7 @@
static boolean_t
nanov2_check(nanozonev2_t *nanozone)
{
- // Does nothing, just like Nano V1.
+ // Does nothing
return 1;
}
@@ -1494,6 +1593,10 @@
nanov2_meta_index_t metablock_meta_index =
nanov2_metablock_meta_index(mapped_nanozone);
nanov2_region_t *region = mapped_nanozone->first_region_base;
+ // Use a single, consistent snapshot of current_region_next_arena throughout
+ // iteration, ignoring any arenas or regions allocated after it.
+ nanov2_arena_t *current_region_next_arena = os_atomic_load(
+ &mapped_nanozone->current_region_next_arena, acquire);
int region_index = 0;
while (region) {
printer("\nRegion %d: base address %p\n", region_index, region);
@@ -1507,7 +1610,7 @@
nanov2_arena_t *arena = nanov2_first_arena_for_region(region);
nanov2_arena_t *limit_arena = nanov2_limit_arena_for_region(
- mapped_nanozone, region);
+ mapped_nanozone, region, current_region_next_arena);
int arena_index = 0;
while (arena < limit_arena) {
// Find the metadata block and process every entry, apart from the
@@ -1648,7 +1751,7 @@
}
region = nanov2_next_region_for_region_offset(mapped_nanozone, region,
- region_offset);
+ region_offset, current_region_next_arena);
region_index++;
}
}
@@ -1670,7 +1773,7 @@
static void
nanov2_log(malloc_zone_t *zone, void *log_address)
{
- // Does nothing, just like Nano V1.
+ // Does nothing
}
static void
@@ -1699,7 +1802,7 @@
}
static void
-null_printer(const char __unused *fmt, ...)
+nanov2_null_printer(const char __unused *fmt, ...)
{
}
@@ -1708,7 +1811,7 @@
memory_reader_t reader, print_task_printer_t printer,
malloc_statistics_t *stats)
{
- printer = printer ? printer : null_printer;
+ printer = printer ? printer : nanov2_null_printer;
reader = !reader && task == mach_task_self() ? _malloc_default_reader : reader;
kern_return_t err;
@@ -1736,6 +1839,8 @@
// Iterate over each arena in each region. Within each region, add
// statistics for each slot in each block, excluding the meta data block.
+ nanov2_arena_t *current_region_next_arena = os_atomic_load(
+ &mapped_nanozone->current_region_next_arena, acquire);
for (region = mapped_nanozone->first_region_base; region;) {
nanov2_region_t *mapped_region;
err = reader(task, (vm_address_t)region, sizeof(nanov2_region_t), (void **)&mapped_region);
@@ -1745,7 +1850,8 @@
}
off_t region_offset = (uintptr_t)mapped_region - (uintptr_t)region;
for (arena = nanov2_first_arena_for_region(region);
- arena < nanov2_limit_arena_for_region(mapped_nanozone, region);
+ arena < nanov2_limit_arena_for_region(mapped_nanozone, region,
+ current_region_next_arena);
arena++) {
nanov2_arena_metablock_t *meta_block =
nanov2_metablock_address_for_ptr(mapped_nanozone, arena);
@@ -1773,6 +1879,8 @@
case SLOT_MADVISING:
// FALLTHRU
case SLOT_MADVISED:
+ // FALLTHRU
+ case SLOT_GUARD:
// These blocks have no active content.
break;
case SLOT_FULL:
@@ -1795,7 +1903,7 @@
}
}
region = nanov2_next_region_for_region_offset(mapped_nanozone,
- region, region_offset);
+ region, region_offset, current_region_next_arena);
}
return KERN_SUCCESS;
}
@@ -1868,25 +1976,40 @@
return 0;
}
+ // Atomically load the value of current_region_next_arena. No thread is
+ // allowed to allocate from an arena until it observes a greater value of
+ // current_region_next_arena, which must have happened before now if we're
+ // being called in the context of a deallocation, so we can safely use it as
+ // the upper bound for an overall address range check.
+ nanov2_arena_t *current_region_next_arena = os_atomic_load(
+ &nanozone->current_region_next_arena, relaxed);
+
// Bounds check against the active address space.
if (ptr < (void *)nanozone->first_region_base ||
- ptr > (void *)nanozone->current_region_next_arena) {
+ ptr > (void *)current_region_next_arena) {
return 0;
}
#if NANOV2_MULTIPLE_REGIONS
// Need to check that the region part is valid because there could be holes.
// Do this only if we know there is a hole.
- // NOTE: in M2 convergence, use a hashed structure to make this more
- // efficient.
- if (nanozone->statistics.region_address_clashes) {
+ //
+ // If we're looking at a legitimately-allocated nano pointer, a load-acquire
+ // of current_region_next_arena must have already happened when its
+ // containing arena was first allocated from, so any region_address_clashes
+ // increment that preceded the store-release of current_region_next_arena
+ // should be visible.
+ //
+ // TODO: use a hashed structure to make this more efficient.
+ if (os_atomic_load(&nanozone->statistics.region_address_clashes, relaxed)) {
nanov2_region_t *ptr_region = nanov2_region_address_for_ptr(ptr);
nanov2_region_t *region = nanozone->first_region_base;
while (region) {
if (ptr_region == region) {
break;
}
- region = nanov2_next_region_for_region(nanozone, region);
+ region = nanov2_next_region_for_region(nanozone, region,
+ current_region_next_arena);
}
if (!region) {
// Reached the end of the region list without matching - not a
@@ -2015,45 +2138,62 @@
// Allocates a new region adjacent to the current one. If the allocation fails,
// keep sliding up by the size of a region until we either succeed or run out of
-// address space. The caller must own the Nanozone regions lock.
-MALLOC_NOEXPORT boolean_t
+// address space. The caller must own the Nanozone regions lock. Returns the
+// first arena of the newly-allocated region if successful, or NULL otherwise.
+MALLOC_NOEXPORT nanov2_arena_t *
nanov2_allocate_new_region(nanozonev2_t *nanozone)
{
#if NANOV2_MULTIPLE_REGIONS
- boolean_t result = FALSE;
+ bool allocated = false;
_malloc_lock_assert_owner(&nanozone->regions_lock);
- nanov2_region_t *current_region = nanozone->current_region_base;
- nanov2_region_t *next_region = (nanov2_region_t *)nanozone->current_region_limit;
+ nanov2_region_t *current_region = nanov2_current_region_base(
+ os_atomic_load(&nanozone->current_region_next_arena, relaxed));
+ nanov2_region_t *next_region = current_region + 1;
while ((void *)next_region <= nanov2_max_region_base.addr) {
if (nanov2_allocate_region(next_region)) {
- nanozone->current_region_base = next_region;
- nanozone->current_region_next_arena = (nanov2_arena_t *)next_region;
- nanozone->current_region_limit = next_region + 1;
nanozone->statistics.allocated_regions++;
- result = TRUE;
+ allocated = true;
break;
}
next_region++;
- nanozone->statistics.region_address_clashes++;
- }
-
- if (result) {
- // Link this region to the previous one.
- nanov2_region_linkage_t *current_region_linkage =
- nanov2_region_linkage_for_region(nanozone, current_region);
- nanov2_region_linkage_t *next_region_linkage =
- nanov2_region_linkage_for_region(nanozone, next_region);
- uint16_t offset = next_region - current_region;
- current_region_linkage->next_region_offset = offset;
- next_region_linkage->next_region_offset = 0;
- }
-
- return result;
+
+ // Loaded atomically in nanov2_pointer_size() to determine whether or
+ // not it's necessary to walk the region list, so we need to increment
+ // atomically here. Published by the store-release of
+ // current_region_next_arena.
+ os_atomic_inc(&nanozone->statistics.region_address_clashes, relaxed);
+ }
+
+ if (!allocated) {
+ return NULL;
+ }
+
+ // Link this region to the previous one.
+ nanov2_region_linkage_t *current_region_linkage =
+ nanov2_region_linkage_for_region(nanozone, current_region);
+
+ // The linkage of the next region is in pristine memory, so already zero -
+ // don't touch it.
+
+ // Store-release the linkage update so any dependent loads through it
+ // observe the (implicit zero-)initialization of the next region.
+ uint16_t offset = next_region - current_region;
+ os_atomic_store(¤t_region_linkage->next_region_offset, offset,
+ release);
+
+ // Store-release the update to current_region_next_arena to publish the
+ // linkage update. Pairs with load-acquires of current_region_next_arena
+ // followed by walks of the region list.
+ nanov2_arena_t *first_arena = nanov2_first_arena_for_region(next_region);
+ os_atomic_store(&nanozone->current_region_next_arena, first_arena + 1,
+ release);
+
+ return first_arena;
#else // NANOV2_MULTIPLE_REGIONS
// On iOS, only one region is supported, so we fail since the first
// region is allocated separately.
- return FALSE;
+ return NULL;
#endif // CONFIG_NANOV2_MULTIPLE_REGIONS
}
#endif // OS_VARIANT_NOTRESOLVED
@@ -2150,8 +2290,7 @@
ptr = nanov2_slot_in_block_ptr(blockp, size_class, slot);
}
- nanov2_free_slot_t *slotp =
- (nanov2_free_slot_t *)os_atomic_force_dependency_on(ptr,
+ nanov2_free_slot_t *slotp = os_atomic_inject_dependency(ptr,
(unsigned long)old_meta_view.bits);
if (from_free_list) {
// We grabbed the item from the free list. Check the free list canary
@@ -2160,7 +2299,7 @@
// write to it.
uintptr_t guard = os_atomic_load(&slotp->double_free_guard, relaxed);
if ((guard ^ nanozone->slot_freelist_cookie) != (uintptr_t)ptr) {
- malloc_zone_error(MALLOC_ABORT_ON_CORRUPTION, false,
+ malloc_zone_error(MALLOC_ABORT_ON_CORRUPTION, true,
"Heap corruption detected, free list is damaged at %p\n"
"*** Incorrect guard value: %lu\n", ptr, guard);
__builtin_unreachable();
@@ -2405,8 +2544,13 @@
start_region = nanov2_region_address_for_ptr(arena);
nanov2_arena_t *start_arena = arena;
nanov2_region_t *region = start_region;
- nanov2_arena_t *limit_arena = nanov2_limit_arena_for_region(nanozone, start_region);
- nanov2_arena_t *initial_region_next_arena = nanozone->current_region_next_arena;
+ // The load-acquire pairs with store-release in nanov2_allocate_new_region()
+ // to make the most recent region linkage update visible when we load it in
+ // nanov2_next_region_for_region() below.
+ nanov2_arena_t *initial_region_next_arena = os_atomic_load(
+ &nanozone->current_region_next_arena, acquire);
+ nanov2_arena_t *limit_arena = nanov2_limit_arena_for_region(nanozone,
+ start_region, initial_region_next_arena);
do {
nanov2_block_meta_t *block_metap = nanov2_find_block_in_arena(nanozone,
arena, size_class, start_block);
@@ -2442,13 +2586,15 @@
start_block = NULL;
arena++;
if (arena >= limit_arena) {
- region = nanov2_next_region_for_region(nanozone, region);
+ region = nanov2_next_region_for_region(nanozone, region,
+ initial_region_next_arena);
if (!region) {
// Reached the last region -- loop back to the first.
region = nanozone->first_region_base;
}
arena = nanov2_first_arena_for_region(region);
- limit_arena = nanov2_limit_arena_for_region(nanozone, region);
+ limit_arena = nanov2_limit_arena_for_region(nanozone, region,
+ initial_region_next_arena);
}
} while (arena != start_arena);
@@ -2459,24 +2605,42 @@
}
// Allocate a new arena and maybe a new region. To do either of those
- // things, we need to take the regions_lock. After doing so, check that
- // the state is unchanged. If it has, just assume that we might have some
- // new space to allocate into and try again.
+ // things, we need to take the regions_lock. After doing so, check that the
+ // state is unchanged. If it has, just assume that we might have some new
+ // space to allocate into and try again.
+
boolean_t failed = FALSE;
- arena = initial_region_next_arena;
+
_malloc_lock_lock(&nanozone->regions_lock);
- if (nanozone->current_region_next_arena == arena) {
- if ((void *)arena >= nanozone->current_region_limit) {
+ nanov2_arena_t *current_region_next_arena = os_atomic_load(
+ &nanozone->current_region_next_arena, relaxed);
+ if (current_region_next_arena == initial_region_next_arena) {
+ if (nanov2_current_region_next_arena_is_limit(
+ current_region_next_arena)) {
// Reached the end of the region. Allocate a new one, if we can.
- if (nanov2_allocate_new_region(nanozone)) {
- arena = nanozone->current_region_next_arena++;
- } else {
+ arena = nanov2_allocate_new_region(nanozone);
+ if (!arena) {
failed = TRUE;
}
} else {
- // Assign the new arena, in the same region.
- nanozone->current_region_next_arena = arena + 1;
- }
+ // Assign the new arena, in the current region.
+ arena = current_region_next_arena;
+
+ // Bump current_region_next_arena by 1. No need for an atomic add
+ // because we're under the regions_lock.
+ os_atomic_store(&nanozone->current_region_next_arena,
+ current_region_next_arena + 1, relaxed);
+ }
+
+ // Set up the guard blocks for the new arena, if requested
+ if (!failed) {
+ nanov2_init_guard_blocks(nanozone, arena);
+ }
+ } else {
+ // The arena just before current_region_next_arena is always the most
+ // recently allocated arena. Let's retry from that arena, which was
+ // allocated in the time since we started our last try.
+ arena = current_region_next_arena - 1;
}
_malloc_lock_unlock(&nanozone->regions_lock);
@@ -2710,12 +2874,6 @@
// Prevent overwriting the function pointers in basic_zone.
mprotect(nanozone, sizeof(nanozone->basic_zone), PROT_READ);
- // Nano V2 zone does not support MALLOC_ADD_GUARD_PAGES
- if (debug_flags & MALLOC_ADD_GUARD_PAGES) {
- malloc_report(ASL_LEVEL_INFO, "nano does not support guard pages\n");
- debug_flags &= ~MALLOC_ADD_GUARD_PAGES;
- }
-
// Set up the remainder of the nanozonev2 structure
nanozone->debug_flags = debug_flags;
nanozone->helper_zone = helper_zone;
@@ -2758,14 +2916,16 @@
}
nanov2_region_linkage_t *region_linkage =
nanov2_region_linkage_for_region(nanozone, region);
- region_linkage->next_region_offset = 0;
+ os_atomic_store(®ion_linkage->next_region_offset, 0, relaxed);
// Install the first region and pre-allocate the first arena.
nanozone->first_region_base = region;
- nanozone->current_region_base = region;
- nanozone->current_region_next_arena = ((nanov2_arena_t *)region) + 1;
- nanozone->current_region_limit = region + 1;
+ os_atomic_store(&nanozone->current_region_next_arena,
+ ((nanov2_arena_t *)region) + 1, release);
nanozone->statistics.allocated_regions = 1;
+
+ // Set up the guard blocks for the initial arena, if requested
+ nanov2_init_guard_blocks(nanozone, (nanov2_arena_t *)region);
return (malloc_zone_t *)nanozone;
}