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--- /dev/null
+++ libmalloc/libmalloc-283/src/magazine_small.c
@@ -0,0 +1,2485 @@
+/*
+ * Copyright (c) 2015 Apple Inc. All rights reserved.
+ *
+ * @APPLE_LICENSE_HEADER_START@
+ *
+ * This file contains Original Code and/or Modifications of Original Code
+ * as defined in and that are subject to the Apple Public Source License
+ * Version 2.0 (the 'License'). You may not use this file except in
+ * compliance with the License. Please obtain a copy of the License at
+ * http://www.opensource.apple.com/apsl/ and read it before using this
+ * file.
+ *
+ * The Original Code and all software distributed under the License are
+ * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
+ * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
+ * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
+ * Please see the License for the specific language governing rights and
+ * limitations under the License.
+ *
+ * @APPLE_LICENSE_HEADER_END@
+ */
+
+#include "internal.h"
+
+
+/********************* SMALL FREE LIST UTILITIES ************************/
+
+#pragma mark meta header helpers
+
+/*
+ * Mark a block as free. Only the first quantum of a block is marked thusly,
+ * the remainder are marked "middle".
+ */
+static MALLOC_INLINE void
+small_meta_header_set_is_free(msize_t *meta_headers, msize_t index, msize_t msize)
+{
+ meta_headers[index] = msize | SMALL_IS_FREE;
+}
+
+/*
+ * Mark a block as not free, preserving its size.
+ */
+static MALLOC_INLINE void
+small_meta_header_set_not_free(msize_t *meta_headers, msize_t index)
+{
+ meta_headers[index] &= ~SMALL_IS_FREE;
+}
+
+/*
+ * Mark a block as in use. Only the first quantum of a block is marked thusly,
+ * the remainder are marked "middle".
+ */
+static MALLOC_INLINE void
+small_meta_header_set_in_use(msize_t *meta_headers, msize_t index, msize_t msize)
+{
+ meta_headers[index] = msize;
+}
+
+/*
+ * Mark a quantum as being the second or later in a block.
+ */
+static MALLOC_INLINE void
+small_meta_header_set_middle(msize_t *meta_headers, msize_t index)
+{
+ meta_headers[index] = 0;
+}
+
+static MALLOC_INLINE MALLOC_ALWAYS_INLINE
+mag_index_t
+small_mag_get_thread_index(void)
+{
+#if CONFIG_SMALL_USES_HYPER_SHIFT
+ if (os_likely(_os_cpu_number_override == -1)) {
+ return _os_cpu_number() >> hyper_shift;
+ } else {
+ return _os_cpu_number_override >> hyper_shift;
+ }
+#else // CONFIG_SMALL_USES_HYPER_SHIFT
+ if (os_likely(_os_cpu_number_override == -1)) {
+ return _os_cpu_number();
+ } else {
+ return _os_cpu_number_override;
+ }
+#endif // CONFIG_SMALL_USES_HYPER_SHIFT
+}
+
+#pragma mark in-place free list
+
+static MALLOC_INLINE void
+small_inplace_checksum_ptr(rack_t *rack, inplace_linkage_s *linkage, void *ptr)
+{
+ uintptr_t checksum = free_list_gen_checksum((uintptr_t)ptr ^ rack->cookie ^ (uintptr_t)rack);
+ linkage->checksum = checksum;
+ linkage->ptr = ptr;
+}
+
+static MALLOC_INLINE free_list_t
+small_inplace_unchecksum_ptr(rack_t *rack, inplace_linkage_s *linkage)
+{
+ if (linkage->checksum != (uint8_t)free_list_gen_checksum((uintptr_t)linkage->ptr ^ rack->cookie ^ (uintptr_t)rack)) {
+ free_list_checksum_botch(rack, linkage, linkage->ptr);
+ __builtin_trap();
+ }
+
+ return (free_list_t){ .p = linkage->ptr };
+}
+
+static MALLOC_INLINE free_list_t
+small_inplace_unchecksum_ptr_task(task_t task, memory_reader_t reader,
+ print_task_printer_t printer, rack_t *rack, inplace_linkage_s *linkage)
+{
+ inplace_linkage_s *mapped_linkage;
+ rack_t *mapped_rack;
+ if (reader(task, (vm_address_t)linkage, sizeof(*linkage),
+ (void **)&mapped_linkage)) {
+ printer("Unable to map small linkage pointer %p\n", linkage);
+ return (free_list_t){ .p = NULL };
+ }
+
+ if (reader(task, (vm_address_t)rack,
+ sizeof(struct rack_s), (void **)&mapped_rack)) {
+ printer("Failed to map small rack\n");
+ return (free_list_t){ .p = NULL };
+ }
+
+ if (mapped_linkage->checksum != (uint8_t)free_list_gen_checksum(
+ (uintptr_t)mapped_linkage->ptr ^ mapped_rack->cookie ^ (uintptr_t)rack)) {
+ free_list_checksum_botch(rack, linkage, mapped_linkage->ptr);
+ __builtin_trap();
+ }
+
+ return (free_list_t){ .p = mapped_linkage->ptr };
+}
+
+static MALLOC_INLINE free_list_t
+small_inplace_free_entry_get_previous(rack_t *rack, small_inplace_free_entry_t ptr)
+{
+ return small_inplace_unchecksum_ptr(rack, &ptr->previous);
+}
+
+static MALLOC_INLINE void
+small_inplace_free_entry_set_previous(rack_t *rack, small_inplace_free_entry_t entry, free_list_t previous)
+{
+ small_inplace_checksum_ptr(rack, &entry->previous, previous.p);
+}
+
+static MALLOC_INLINE free_list_t
+small_inplace_free_entry_get_next(rack_t *rack, small_inplace_free_entry_t ptr)
+{
+ return small_inplace_unchecksum_ptr(rack, &ptr->next);
+}
+
+static MALLOC_INLINE free_list_t
+small_inplace_free_entry_get_next_task(task_t task, memory_reader_t reader,
+ print_task_printer_t printer, rack_t *rack,
+ small_inplace_free_entry_t ptr)
+{
+ return small_inplace_unchecksum_ptr_task(task, reader, printer, rack,
+ &ptr->next);
+}
+
+static MALLOC_INLINE void
+small_inplace_free_entry_set_next(rack_t *rack, small_inplace_free_entry_t entry, free_list_t next)
+{
+ small_inplace_checksum_ptr(rack, &entry->next, next.p);
+}
+
+#pragma mark OOB free list
+
+// Returns true if the address and size of the free list entry would result
+// in the free entry being the only data on a given page.
+static MALLOC_INLINE boolean_t
+small_needs_oob_free_entry(void *ptr, msize_t msize)
+{
+ return ((trunc_page_quanta((uintptr_t)ptr) == (uintptr_t)ptr) && (SMALL_BYTES_FOR_MSIZE(msize) >= vm_kernel_page_size));
+}
+
+// Returns true if the address given lies within the region's OOB free
+// list entries, rather than a free_list_t in the region's heap space.
+static MALLOC_INLINE boolean_t
+small_is_oob_free_entry(free_list_t ptr)
+{
+ small_region_t region = SMALL_REGION_FOR_PTR(ptr.p);
+ return (((uintptr_t)ptr.p >= (uintptr_t)®ion->small_oob_free_entries[0]) &&
+ ((uintptr_t)ptr.p < (uintptr_t)®ion->small_oob_free_entries[SMALL_OOB_COUNT]));
+}
+
+static MALLOC_INLINE void
+small_oob_free_entry_set_previous(oob_free_entry_t oobe, free_list_t previous)
+{
+ oobe->prev = (uintptr_t)previous.p;
+}
+
+static MALLOC_INLINE free_list_t
+small_oob_free_entry_get_previous(oob_free_entry_t oobe)
+{
+ return (free_list_t){ .p = (void *)oobe->prev };
+}
+
+static MALLOC_INLINE void
+small_oob_free_entry_set_next(oob_free_entry_t oobe, free_list_t next)
+{
+ oobe->next = (uintptr_t)next.p;
+}
+
+static MALLOC_INLINE free_list_t
+small_oob_free_entry_get_next(oob_free_entry_t oobe)
+{
+ return (free_list_t){ .p = (void *)oobe->next };
+}
+
+static MALLOC_INLINE free_list_t
+small_oob_free_entry_get_next_task(task_t task, memory_reader_t reader,
+ print_task_printer_t printer, oob_free_entry_t oobe)
+{
+ oob_free_entry_t mapped_oobe;
+ if (reader(task, (vm_address_t)oobe, sizeof(*oobe),
+ (void **)&mapped_oobe)) {
+ printer("Failed to map small oobe pointer\n");
+ return (free_list_t){ .p = NULL };
+ }
+ return (free_list_t){ .p = (void *)mapped_oobe->next };
+}
+
+static MALLOC_INLINE void *
+small_oob_free_entry_get_ptr(oob_free_entry_t oobe)
+{
+ if (!(oobe->ptr & SMALL_IS_OOB)) {
+ return NULL;
+ }
+ small_region_t region = SMALL_REGION_FOR_PTR(oobe);
+ uint16_t block = oobe->ptr & ~SMALL_IS_OOB;
+ return (void *)((uintptr_t)region + (block << SHIFT_SMALL_QUANTUM));
+}
+
+static MALLOC_INLINE void *
+small_oob_free_entry_get_ptr_task(task_t task, memory_reader_t reader,
+ print_task_printer_t printer, oob_free_entry_t oobe)
+{
+ // We need to map the oob_free_entry_t to read the pointer value.
+ oob_free_entry_t mapped_oobe;
+ if (reader(task, (vm_address_t)oobe, sizeof(*oobe),
+ (void **)&mapped_oobe)) {
+ printer("Failed to map small oobe pointer\n");
+ return NULL;
+ }
+
+ if (!(mapped_oobe->ptr & SMALL_IS_OOB)) {
+ return NULL;
+ }
+
+ // The rest of this code works with target process addresses and returns an
+ // address in the target process.
+ small_region_t region = SMALL_REGION_FOR_PTR(oobe);
+ uint16_t block = mapped_oobe->ptr & ~SMALL_IS_OOB;
+ return (void *)((uintptr_t)region + (block << SHIFT_SMALL_QUANTUM));
+}
+
+static MALLOC_INLINE void
+small_oob_free_entry_set_ptr(oob_free_entry_t oobe, void *ptr)
+{
+ oobe->ptr = SMALL_IS_OOB | (SMALL_OFFSET_FOR_PTR(ptr) >> SHIFT_SMALL_QUANTUM);
+}
+
+static MALLOC_INLINE void
+small_oob_free_entry_set_free(oob_free_entry_t oobe)
+{
+ oobe->prev = ~0;
+ oobe->next = ~0;
+ oobe->ptr = 0;
+}
+
+// Finds the first unused OOB free list entry in the pointer's region.
+// Returns NULL if all of the OOB entries are used.
+static MALLOC_INLINE oob_free_entry_t
+small_oob_free_find_empty(void *ptr, msize_t msize)
+{
+ small_region_t region = SMALL_REGION_FOR_PTR(ptr);
+
+ // There are 61 of these entries at the end of a small region.
+ // If this changes, then a linear search through the list may
+ // become an unsuitable choice.
+ for (int i=0; i < SMALL_OOB_COUNT; i++) {
+ if (region->small_oob_free_entries[i].ptr == 0) {
+ return ®ion->small_oob_free_entries[i];
+ }
+ }
+
+#if DEBUG_MALLOC
+ malloc_report(ASL_LEVEL_INFO, "used all slots of OOB entries\n");
+#endif
+ return NULL;
+}
+
+static MALLOC_INLINE oob_free_entry_t
+small_oob_free_find_ptr(void *ptr, msize_t msize)
+{
+ small_region_t region = SMALL_REGION_FOR_PTR(ptr);
+
+ // There are 61 of these entries at the end of a small region.
+ // If this changes, then a linear search through the list may
+ // become an unsuitable choice.
+ for (int i=0; i < SMALL_OOB_COUNT; i++) {
+ oob_free_entry_t oob = ®ion->small_oob_free_entries[i];
+ if (small_oob_free_entry_get_ptr(oob) == ptr &&
+ oob->ptr & SMALL_IS_OOB) {
+ return ®ion->small_oob_free_entries[i];
+ }
+ }
+
+ return NULL;
+}
+
+#pragma mark generic free list
+
+static MALLOC_INLINE void
+small_free_list_set_previous(rack_t *rack, free_list_t entry, free_list_t previous)
+{
+ if (small_is_oob_free_entry(entry)) {
+ small_oob_free_entry_set_previous(entry.oob, previous);
+ } else {
+ small_inplace_free_entry_set_previous(rack, entry.small_inplace, previous);
+ }
+}
+
+static MALLOC_INLINE free_list_t
+small_free_list_get_previous(rack_t *rack, free_list_t ptr)
+{
+ MALLOC_ASSERT(ptr.p);
+ if (small_is_oob_free_entry(ptr)) {
+ return small_oob_free_entry_get_previous(ptr.oob);
+ } else {
+ return small_inplace_free_entry_get_previous(rack, ptr.small_inplace);
+ }
+}
+
+static MALLOC_INLINE void
+small_free_list_set_next(rack_t *rack, free_list_t entry, free_list_t next)
+{
+ if (small_is_oob_free_entry(entry)) {
+ small_oob_free_entry_set_next(entry.oob, next);
+ } else {
+ small_inplace_free_entry_set_next(rack, entry.small_inplace, next);
+ }
+}
+
+static MALLOC_INLINE free_list_t
+small_free_list_get_next(rack_t *rack, free_list_t ptr)
+{
+ MALLOC_ASSERT(ptr.p);
+ if (small_is_oob_free_entry(ptr)) {
+ return small_oob_free_entry_get_next(ptr.oob);
+ } else {
+ return small_inplace_free_entry_get_next(rack, ptr.small_inplace);
+ }
+}
+
+static MALLOC_INLINE free_list_t
+small_free_list_get_next_task(task_t task, memory_reader_t reader,
+ print_task_printer_t printer, rack_t *rack, free_list_t ptr)
+{
+ MALLOC_ASSERT(ptr.p);
+ if (small_is_oob_free_entry(ptr)) {
+ return small_oob_free_entry_get_next_task(task, reader, printer, ptr.oob);
+ } else {
+ return small_inplace_free_entry_get_next_task(task, reader, printer,
+ rack, ptr.small_inplace);
+ }
+}
+
+static MALLOC_INLINE void *
+small_free_list_get_ptr(free_list_t ptr)
+{
+ if (!ptr.p) {
+ return NULL;
+ } else if (small_is_oob_free_entry(ptr)) {
+ return small_oob_free_entry_get_ptr(ptr.oob);
+ } else {
+ return (void *)ptr.p;
+ }
+}
+
+static MALLOC_INLINE void *
+small_free_list_get_ptr_task(task_t task, memory_reader_t reader,
+ print_task_printer_t printer, free_list_t ptr)
+{
+ if (!ptr.p) {
+ return NULL;
+ } else if (small_is_oob_free_entry(ptr)) {
+ return small_oob_free_entry_get_ptr_task(task, reader, printer, ptr.oob);
+ } else {
+ return (void *)ptr.p;
+ }
+}
+
+// Returns a free_list_t that is either inline or not based on the
+// pointer and msize.
+static MALLOC_INLINE free_list_t
+small_free_list_from_ptr(rack_t *rack, void *ptr, msize_t msize)
+{
+ MALLOC_ASSERT(msize);
+
+ // The default is to put the free_list_t in the memory that
+ // the pointer leads to.
+ free_list_t entry;
+ entry.p = ptr;
+
+ // If the pointer is page aligned, and the msize is greater
+ // than a whole page, then we try and put the entry in
+ // the out-of-band area instead.
+ if (small_needs_oob_free_entry(ptr, msize)) {
+ oob_free_entry_t oobe = small_oob_free_find_empty(ptr, msize);
+ if (oobe) {
+ small_oob_free_entry_set_ptr(oobe, ptr);
+ entry.oob = oobe;
+ }
+ }
+
+ return entry;
+}
+
+static MALLOC_INLINE void
+small_free_mark_free(rack_t *rack, free_list_t entry, msize_t msize)
+{
+ // Marks both the start and end block of a free-list entry as free.
+ void *ptr = small_free_list_get_ptr(entry);
+ msize_t *meta_headers = SMALL_META_HEADER_FOR_PTR(ptr);
+ uintptr_t start_index = SMALL_META_INDEX_FOR_PTR(ptr);
+ uintptr_t end_index = SMALL_META_INDEX_FOR_PTR(ptr + SMALL_BYTES_FOR_MSIZE(msize) - 1);
+ MALLOC_ASSERT(start_index <= end_index);
+
+ small_meta_header_set_is_free(meta_headers, start_index, msize);
+ small_meta_header_set_is_free(meta_headers, end_index, msize);
+}
+
+static MALLOC_INLINE void
+small_free_mark_middle(rack_t *rack, free_list_t entry, msize_t msize)
+{
+ // Marks both the start and end block of a free-list entry as "middle" (unfree).
+ void *ptr = small_free_list_get_ptr(entry);
+ msize_t *meta_headers = SMALL_META_HEADER_FOR_PTR(ptr);
+ uintptr_t start_index = SMALL_META_INDEX_FOR_PTR(ptr);
+ uintptr_t end_index = SMALL_META_INDEX_FOR_PTR(ptr + SMALL_BYTES_FOR_MSIZE(msize) - 1);
+ MALLOC_ASSERT(start_index <= end_index);
+ MALLOC_ASSERT((meta_headers[start_index] & ~SMALL_IS_FREE) == msize);
+
+ small_meta_header_set_middle(meta_headers, start_index);
+ small_meta_header_set_middle(meta_headers, end_index);
+}
+
+static MALLOC_INLINE void
+small_free_mark_unfree(rack_t *rack, free_list_t entry, msize_t msize)
+{
+ // Marks both the start and end block of a free-list entry as not free.
+ void *ptr = small_free_list_get_ptr(entry);
+ msize_t *meta_headers = SMALL_META_HEADER_FOR_PTR(ptr);
+ uintptr_t start_index = SMALL_META_INDEX_FOR_PTR(ptr);
+ uintptr_t end_index = SMALL_META_INDEX_FOR_PTR(ptr + SMALL_BYTES_FOR_MSIZE(msize) - 1);
+ MALLOC_ASSERT(start_index <= end_index);
+
+ small_meta_header_set_not_free(meta_headers, start_index);
+ small_meta_header_set_not_free(meta_headers, end_index);
+}
+
+static MALLOC_INLINE unsigned int
+small_free_list_count(task_t task, memory_reader_t reader,
+ print_task_printer_t printer, rack_t *rack, free_list_t ptr)
+{
+ unsigned int count = 0;
+ while (ptr.p) {
+ count++;
+ ptr = small_free_list_get_next_task(task, reader, printer, rack, ptr);
+ }
+ return count;
+}
+
+/*
+ * Adds an item to the proper free list, and also marks the meta-header of the
+ * block properly.
+ * Assumes szone has been locked
+ */
+static free_list_t
+small_free_list_add_ptr(rack_t *rack, magazine_t *small_mag_ptr, void *ptr, msize_t msize)
+{
+ grain_t slot = SMALL_FREE_SLOT_FOR_MSIZE(rack, msize);
+ free_list_t free_head = small_mag_ptr->mag_free_list[slot];
+
+ // This will either return the free_list_t for the current pointer, or attempt
+ // to reserve an OOB entry for us.
+ free_list_t free_ptr = small_free_list_from_ptr(rack, ptr, msize);
+
+#if DEBUG_MALLOC
+ if (LOG(szone, ptr)) {
+ malloc_report(ASL_LEVEL_INFO, "in %s, ptr=%p, msize=%d\n", __FUNCTION__, ptr, msize);
+ }
+ if (((uintptr_t)ptr) & (SMALL_QUANTUM - 1)) {
+ malloc_zone_error(rack->debug_flags, true, "small_free_list_add_ptr: Unaligned ptr %p\n", ptr);
+ }
+#endif
+
+ small_free_list_set_previous(rack, free_ptr, (free_list_t){ .p = NULL });
+ small_free_list_set_next(rack, free_ptr, free_head);
+
+ // Set the start and end blocks of the meta header as "free". Marking the last block
+ // allows coalescing the regions when we free adjacent regions.
+ small_free_mark_free(rack, free_ptr, msize);
+
+ if (small_free_list_get_ptr(free_head)) {
+#if DEBUG_MALLOC
+ if (small_free_list_get_previous(szone, free_head)) {
+ malloc_zone_error(rack->debug_flags, true, "small_free_list_add_ptr: Internal invariant broken (free_head->previous != NULL)\n"
+ "ptr=%p slot=%d free_head=%p previous=%p\n", ptr, slot, (void *)free_head, free_head->previous.p);
+ }
+ if (!SMALL_PTR_IS_FREE(small_free_list_get_ptr(free_head))) {
+ malloc_zone_error(rack->debug_flags, true, "small_free_list_add_ptr: Internal invariant broken (free_head is not a free pointer)\n"
+ "ptr=%p slot=%d free_head=%p\n", ptr, slot, (void *)small_free_list_get_ptr(free_head));
+ }
+#endif
+ small_free_list_set_previous(rack, free_head, free_ptr);
+ } else {
+ BITMAPN_SET(small_mag_ptr->mag_bitmap, slot);
+ }
+
+ small_mag_ptr->mag_free_list[slot] = free_ptr;
+ return free_ptr;
+}
+
+/*
+ * Removes the item pointed to by ptr in the proper free list.
+ * Assumes szone has been locked
+ */
+static void
+small_free_list_remove_ptr_no_clear(rack_t *rack, magazine_t *small_mag_ptr, free_list_t entry, msize_t msize)
+{
+ grain_t slot = SMALL_FREE_SLOT_FOR_MSIZE(rack, msize);
+ free_list_t next, previous;
+
+#if DEBUG_MALLOC
+ if (LOG(szone, ptr)) {
+ malloc_report(ASL_LEVEL_INFO, "In %s, ptr=%p, msize=%d\n", __FUNCTION__, ptr, msize);
+ }
+#endif
+
+ previous = small_free_list_get_previous(rack, entry);
+ next = small_free_list_get_next(rack, entry);
+
+ if (!small_free_list_get_ptr(previous)) {
+ // The block to remove is the head of the free list
+#if DEBUG_MALLOC
+ if (small_mag_ptr->mag_free_list[slot] != ptr) {
+ malloc_zone_error(rack->debug_flags, true,
+ "small_free_list_remove_ptr_no_clear: Internal invariant broken (small_mag_ptr->mag_free_list[slot])\n"
+ "ptr=%p slot=%d msize=%d small_mag_ptr->mag_free_list[slot]=%p\n", ptr, slot, msize,
+ (void *)small_mag_ptr->mag_free_list[slot]);
+ return;
+ }
+#endif
+ small_mag_ptr->mag_free_list[slot] = next;
+ if (!small_free_list_get_ptr(next)) {
+ BITMAPN_CLR(small_mag_ptr->mag_bitmap, slot);
+ }
+ } else {
+ // Check that the next pointer of "previous" points to "entry".
+ free_list_t prev_next = small_free_list_get_next(rack, previous);
+ if (small_free_list_get_ptr(prev_next) != small_free_list_get_ptr(entry)) {
+ malloc_zone_error(rack->debug_flags, true,
+ "small_free_list_remove_ptr_no_clear: Internal invariant broken (next ptr of prev) for %p, prev_next=%p\n",
+ small_free_list_get_ptr(entry), small_free_list_get_ptr(prev_next));
+ __builtin_unreachable(); // Always crashes in malloc_zone_error().
+ }
+ small_free_list_set_next(rack, previous, next);
+ }
+
+ if (small_free_list_get_ptr(next)) {
+ // Check that the previous pointer of "next" points to "entry".
+ free_list_t next_prev = small_free_list_get_previous(rack, next);
+ if (small_free_list_get_ptr(next_prev) != small_free_list_get_ptr(entry)) {
+ malloc_zone_error(rack->debug_flags, true,
+ "small_free_list_remove_ptr_no_clear: Internal invariant broken (prev ptr of next) for %p, next_prev=%p\n",
+ small_free_list_get_ptr(entry), small_free_list_get_ptr(next_prev));
+ __builtin_unreachable(); // Always crashes in malloc_zone_error().
+ }
+ small_free_list_set_previous(rack, next, previous);
+ }
+
+ if (small_is_oob_free_entry(entry)) {
+ small_oob_free_entry_set_free(entry.oob);
+ }
+}
+
+static void
+small_free_list_remove_ptr(rack_t *rack, magazine_t *small_mag_ptr, free_list_t entry, msize_t msize)
+{
+ // In the general case we want to ensure we marked these entries as "middle"
+ // while we are in this function. However, when we're moving free list entries
+ // from/to the recirc depot we rely on the metadata bits being intact to
+ // reconstruct the free list. In that case we have to be able to skip this
+ // metadata manipulation.
+ small_free_mark_middle(rack, entry, msize);
+ small_free_list_remove_ptr_no_clear(rack, small_mag_ptr, entry, msize);
+}
+
+// Find a free list entry by its pointer address. This should only really be used
+// by small_finalize_region, or similar, where the free_list_t entry of a known
+// pointer is desired. Otherwise it is cheaper to always pull off the free lists.
+static free_list_t
+small_free_list_find_by_ptr(rack_t *rack, magazine_t *small_mag_ptr, void *ptr, msize_t msize)
+{
+ if (*SMALL_METADATA_FOR_PTR(ptr) == (SMALL_IS_FREE | msize)) {
+ // If the block is marked free, and of size `msize`, then we first must check
+ // if the alignment+size is such that we could have use an OOB-entry.
+ if (small_needs_oob_free_entry(ptr, msize)) {
+ // Scan the OOB entries looking for this address.
+ small_region_t region = SMALL_REGION_FOR_PTR(ptr);
+ for (int i=0; i<SMALL_OOB_COUNT; i++) {
+ if (!region->small_oob_free_entries[i].ptr) {
+ continue;
+ }
+ if (small_oob_free_entry_get_ptr(®ion->small_oob_free_entries[i]) == ptr) {
+ return (free_list_t){ .oob = ®ion->small_oob_free_entries[i] };
+ }
+ }
+ }
+
+ // Otherwise, the freed pointer will be in place.
+ return (free_list_t){ .p = ptr };
+ }
+
+ malloc_zone_error(rack->debug_flags, true,
+ "small_free_list_find_by_ptr: ptr is not free (ptr metadata !SMALL_IS_FREE), "
+ "ptr=%p msize=%d metadata=0x%x\n", ptr, msize, *SMALL_METADATA_FOR_PTR(ptr));
+ __builtin_trap();
+}
+
+void
+small_finalize_region(rack_t *rack, magazine_t *small_mag_ptr)
+{
+ void *last_block, *previous_block;
+ msize_t last_msize, previous_msize, last_index;
+ free_list_t previous;
+
+ // It is possible that the block prior to the last block in the region has
+ // been free'd, but was not coalesced with the free bytes at the end of the
+ // block, since we treat the bytes at the end of the region as "in use" in
+ // the meta headers. Attempt to coalesce the last block with the previous
+ // block, so we don't violate the "no consecutive free blocks" invariant.
+ //
+ // FIXME: If we could calculate the previous small free size in the same
+ // manner as tiny_previous_preceding_free, it would eliminate the
+ // index & previous msize checks, which are a guard against reading
+ // bogus data out of in-use or written-on-freed memory.
+ //
+ // FIXME: Need to investigate how much work would be required to increase
+ // 'mag_bytes_free_at_end' when freeing the preceding block, rather
+ // than performing this workaround.
+ //
+ if (small_mag_ptr->mag_bytes_free_at_end) {
+ last_block = SMALL_REGION_END(small_mag_ptr->mag_last_region) - small_mag_ptr->mag_bytes_free_at_end;
+ last_msize = SMALL_MSIZE_FOR_BYTES(small_mag_ptr->mag_bytes_free_at_end);
+
+ last_index = SMALL_META_INDEX_FOR_PTR(last_block);
+ previous_msize = SMALL_PREVIOUS_MSIZE(last_block);
+
+ if (last_index && (previous_msize <= last_index)) {
+ previous_block = (void *)((uintptr_t)last_block - SMALL_BYTES_FOR_MSIZE(previous_msize));
+
+ if (SMALL_PTR_IS_FREE(previous_block)) {
+ previous = small_free_list_find_by_ptr(rack, small_mag_ptr, previous_block, previous_msize);
+ small_free_list_remove_ptr(rack, small_mag_ptr, previous, previous_msize);
+ last_block = previous_block;
+ last_msize += previous_msize;
+ }
+ }
+
+ // splice last_block into the free list
+ small_free_list_add_ptr(rack, small_mag_ptr, last_block, last_msize);
+ small_mag_ptr->mag_bytes_free_at_end = 0;
+ }
+
+#if CONFIG_ASLR_INTERNAL
+ free_list_t next;
+
+ if (small_mag_ptr->mag_bytes_free_at_start) {
+ last_block = SMALL_REGION_ADDRESS(small_mag_ptr->mag_last_region);
+ last_msize = SMALL_MSIZE_FOR_BYTES(small_mag_ptr->mag_bytes_free_at_start);
+
+ void *next_block = (void *)((uintptr_t)last_block + small_mag_ptr->mag_bytes_free_at_start);
+ if (SMALL_PTR_IS_FREE(next_block)) {
+ msize_t next_msize = SMALL_PTR_SIZE(next_block);
+ next = small_free_list_find_by_ptr(rack, small_mag_ptr, next_block, next_msize);
+ small_free_list_remove_ptr(rack, small_mag_ptr, next, next_msize);
+ last_msize += next_msize;
+ }
+
+ // splice last_block into the free list
+ small_free_list_add_ptr(rack, small_mag_ptr, last_block, last_msize);
+ small_mag_ptr->mag_bytes_free_at_start = 0;
+ }
+#endif
+
+ // TODO: Will we ever need to coalesce the blocks at the beginning and end when we finalize?
+ small_mag_ptr->mag_last_region = NULL;
+}
+
+int
+small_free_detach_region(rack_t *rack, magazine_t *small_mag_ptr, region_t r)
+{
+ unsigned char *ptr = SMALL_REGION_ADDRESS(r);
+ msize_t *meta_headers = SMALL_META_HEADER_FOR_PTR(ptr);
+ uintptr_t start = (uintptr_t)SMALL_REGION_ADDRESS(r);
+ uintptr_t current = start;
+ uintptr_t limit = (uintptr_t)SMALL_REGION_END(r);
+ int total_alloc = 0;
+
+ while (current < limit) {
+ unsigned index = SMALL_META_INDEX_FOR_PTR(current);
+ msize_t msize_and_free = meta_headers[index];
+ boolean_t is_free = msize_and_free & SMALL_IS_FREE;
+ msize_t msize = msize_and_free & ~SMALL_IS_FREE;
+
+ if (!msize) {
+#if DEBUG_MALLOC
+ boolean_t is_free = msize_and_free & SMALL_IS_FREE;
+ malloc_report(ASL_LEVEL_ERR, "*** small_free_detach_region error with %p: msize=%d is_free=%d\n", (void *)current, msize, is_free);
+#endif
+ break;
+ }
+
+ if (is_free) {
+ free_list_t entry = small_free_list_find_by_ptr(rack, small_mag_ptr, (void *)current, msize);
+ small_free_list_remove_ptr_no_clear(rack, small_mag_ptr, entry, msize);
+ } else {
+ total_alloc++;
+ }
+ current += SMALL_BYTES_FOR_MSIZE(msize);
+ }
+ return total_alloc;
+}
+
+size_t
+small_free_reattach_region(rack_t *rack, magazine_t *small_mag_ptr, region_t r)
+{
+ unsigned char *ptr = SMALL_REGION_ADDRESS(r);
+ msize_t *meta_headers = SMALL_META_HEADER_FOR_PTR(ptr);
+ uintptr_t start = (uintptr_t)SMALL_REGION_ADDRESS(r);
+ uintptr_t current = start;
+ uintptr_t limit = (uintptr_t)SMALL_REGION_END(r);
+ size_t total_alloc = 0;
+
+ while (current < limit) {
+ unsigned index = SMALL_META_INDEX_FOR_PTR(current);
+ msize_t msize_and_free = meta_headers[index];
+ boolean_t is_free = msize_and_free & SMALL_IS_FREE;
+ msize_t msize = msize_and_free & ~SMALL_IS_FREE;
+
+ if (!msize) {
+#if DEBUG_MALLOC
+ malloc_report(ASL_LEVEL_ERR, "*** small_free_reattach_region error with %p: msize=%d is_free=%d\n", (void *)current, msize, is_free);
+#endif
+ break;
+ }
+ if (is_free) {
+ small_free_list_add_ptr(rack, small_mag_ptr, (void *)current, msize);
+ } else {
+ total_alloc += SMALL_BYTES_FOR_MSIZE(msize);
+ }
+ current += SMALL_BYTES_FOR_MSIZE(msize);
+ }
+ return total_alloc;
+}
+
+typedef struct {
+ uint16_t pnum, size;
+} small_pg_pair_t;
+
+void
+small_free_scan_madvise_free(rack_t *rack, magazine_t *depot_ptr, region_t r)
+{
+ uintptr_t start = (uintptr_t)SMALL_REGION_ADDRESS(r);
+ uintptr_t current = start;
+ uintptr_t limit = (uintptr_t)SMALL_REGION_END(r);
+ msize_t *meta_headers = SMALL_META_HEADER_FOR_PTR(start);
+ small_pg_pair_t advisory[((SMALL_REGION_PAYLOAD_BYTES + vm_kernel_page_size - 1) >> vm_kernel_page_shift) >>
+ 1]; // 4096bytes stack allocated
+ int advisories = 0;
+
+ // Scan the metadata identifying blocks which span one or more pages. Mark the pages MADV_FREE taking care to preserve free list
+ // management data.
+ while (current < limit) {
+ unsigned index = SMALL_META_INDEX_FOR_PTR(current);
+ msize_t msize_and_free = meta_headers[index];
+ boolean_t is_free = msize_and_free & SMALL_IS_FREE;
+ msize_t msize = msize_and_free & ~SMALL_IS_FREE;
+
+ if (is_free && !msize && (current == start)) {
+#if DEBUG_MALLOC
+ // first block is all free
+ malloc_report(ASL_LEVEL_ERR, "*** small_free_scan_madvise_free first block is all free! %p: msize=%d is_free=%d\n", (void *)current,
+ msize, is_free);
+#endif
+ uintptr_t pgLo = round_page_kernel(start + sizeof(free_list_t) + sizeof(msize_t));
+ uintptr_t pgHi = trunc_page_kernel(start + SMALL_REGION_SIZE - sizeof(msize_t));
+
+ if (pgLo < pgHi) {
+ advisory[advisories].pnum = (pgLo - start) >> vm_kernel_page_shift;
+ advisory[advisories].size = (pgHi - pgLo) >> vm_kernel_page_shift;
+ advisories++;
+ }
+ break;
+ }
+ if (!msize) {
+#if DEBUG_MALLOC
+ malloc_report(ASL_LEVEL_ERR,
+ "*** small_free_scan_madvise_free error with %p: msize=%d is_free=%d\n", (void *)current, msize, is_free);
+#endif
+ break;
+ }
+ if (is_free) {
+ uintptr_t pgLo = round_page_kernel(current + sizeof(free_list_t) + sizeof(msize_t));
+ uintptr_t pgHi = trunc_page_kernel(current + SMALL_BYTES_FOR_MSIZE(msize) - sizeof(msize_t));
+
+ if (pgLo < pgHi) {
+ advisory[advisories].pnum = (pgLo - start) >> vm_kernel_page_shift;
+ advisory[advisories].size = (pgHi - pgLo) >> vm_kernel_page_shift;
+ advisories++;
+ }
+ }
+ current += SMALL_BYTES_FOR_MSIZE(msize);
+ }
+
+ if (advisories > 0) {
+ int i;
+
+ OSAtomicIncrement32Barrier(&(REGION_TRAILER_FOR_SMALL_REGION(r)->pinned_to_depot));
+ SZONE_MAGAZINE_PTR_UNLOCK(depot_ptr);
+ for (i = 0; i < advisories; ++i) {
+ uintptr_t addr = (advisory[i].pnum << vm_page_quanta_shift) + start;
+ size_t size = advisory[i].size << vm_page_quanta_shift;
+
+ mvm_madvise_free(rack, r, addr, addr + size, NULL, rack->debug_flags & MALLOC_DO_SCRIBBLE);
+ }
+ SZONE_MAGAZINE_PTR_LOCK(depot_ptr);
+ OSAtomicDecrement32Barrier(&(REGION_TRAILER_FOR_SMALL_REGION(r)->pinned_to_depot));
+ }
+}
+
+#if CONFIG_RECIRC_DEPOT
+static region_t
+small_find_msize_region(rack_t *rack, magazine_t *small_mag_ptr, mag_index_t mag_index, msize_t msize)
+{
+ void *ptr;
+ grain_t slot = SMALL_FREE_SLOT_FOR_MSIZE(rack, msize);
+ free_list_t *free_list = small_mag_ptr->mag_free_list;
+ free_list_t *the_slot = free_list + slot;
+ free_list_t *limit;
+ unsigned bitmap;
+
+ // Assumes we've locked the magazine
+ CHECK_MAGAZINE_PTR_LOCKED(szone, small_mag_ptr, __PRETTY_FUNCTION__);
+
+ // Look for an exact match by checking the freelist for this msize.
+ ptr = small_free_list_get_ptr(*the_slot);
+ if (ptr) {
+ return SMALL_REGION_FOR_PTR(ptr);
+ }
+
+ // Mask off the bits representing slots holding free blocks smaller than
+ // the size we need.
+ //
+ // BITMAPN_CTZ implementation
+ unsigned idx = slot >> 5;
+ bitmap = 0;
+ unsigned mask = ~((1 << (slot & 31)) - 1);
+ for (; idx < SMALL_FREELIST_BITMAP_WORDS(rack); ++idx) {
+ bitmap = small_mag_ptr->mag_bitmap[idx] & mask;
+ if (bitmap != 0) {
+ break;
+ }
+ mask = ~0U;
+ }
+ // Check for fallthrough: No bits set in bitmap
+ if ((bitmap == 0) && (idx == SMALL_FREELIST_BITMAP_WORDS(rack))) {
+ return NULL;
+ }
+
+ // Start looking at the first set bit, plus 32 bits for every word of
+ // zeroes or entries that were too small.
+ slot = BITMAP32_CTZ((&bitmap)) + (idx * 32);
+
+ limit = free_list + SMALL_FREE_SLOT_COUNT(rack) - 1;
+ free_list += slot;
+
+ if (free_list < limit) {
+ ptr = small_free_list_get_ptr(*free_list);
+ if (ptr) {
+ return SMALL_REGION_FOR_PTR(ptr);
+ } else {
+ /* Shouldn't happen. Fall through to look at last slot. */
+#if DEBUG_MALLOC
+ malloc_report(ASL_LEVEL_ERR, "in small_malloc_from_free_list(), mag_bitmap out of sync, slot=%d\n", slot);
+#endif
+ }
+ }
+
+ // We are now looking at the last slot, which contains blocks equal to, or
+ // due to coalescing of free blocks, larger than (num_small_slots - 1) * (small quantum size).
+ ptr = small_free_list_get_ptr(*limit);
+ if (ptr) {
+ return SMALL_REGION_FOR_PTR(ptr);
+ }
+
+ return NULL;
+}
+
+static boolean_t
+small_get_region_from_depot(rack_t *rack, magazine_t *small_mag_ptr, mag_index_t mag_index, msize_t msize)
+{
+ magazine_t *depot_ptr = &(rack->magazines[DEPOT_MAGAZINE_INDEX]);
+
+ /* FIXME: Would Uniprocessor benefit from recirc and MADV_FREE? */
+ if (rack->num_magazines == 1) { // Uniprocessor, single magazine, so no recirculation necessary
+ return 0;
+ }
+
+#if DEBUG_MALLOC
+ if (DEPOT_MAGAZINE_INDEX == mag_index) {
+ malloc_zone_error(rack->debug_flags, true, "small_get_region_from_depot called for magazine index -1\n", NULL, NULL);
+ return 0;
+ }
+#endif
+
+ SZONE_MAGAZINE_PTR_LOCK(depot_ptr);
+
+ // Appropriate a Depot'd region that can satisfy requested msize.
+ region_trailer_t *node;
+ region_t sparse_region;
+
+ while (1) {
+ sparse_region = small_find_msize_region(rack, depot_ptr, DEPOT_MAGAZINE_INDEX, msize);
+ if (NULL == sparse_region) { // Depot empty?
+ SZONE_MAGAZINE_PTR_UNLOCK(depot_ptr);
+ return 0;
+ }
+
+ node = REGION_TRAILER_FOR_SMALL_REGION(sparse_region);
+ if (0 >= node->pinned_to_depot) {
+ break;
+ }
+
+ SZONE_MAGAZINE_PTR_UNLOCK(depot_ptr);
+ yield();
+ SZONE_MAGAZINE_PTR_LOCK(depot_ptr);
+ }
+
+ // disconnect node from Depot
+ recirc_list_extract(rack, depot_ptr, node);
+
+ // Iterate the region pulling its free entries off the (locked) Depot's free list
+ int objects_in_use = small_free_detach_region(rack, depot_ptr, sparse_region);
+
+ // Transfer ownership of the region
+ MAGAZINE_INDEX_FOR_SMALL_REGION(sparse_region) = mag_index;
+ node->pinned_to_depot = 0;
+
+ // Iterate the region putting its free entries on its new (locked) magazine's free list
+ size_t bytes_inplay = small_free_reattach_region(rack, small_mag_ptr, sparse_region);
+
+ depot_ptr->mag_num_bytes_in_objects -= bytes_inplay;
+ depot_ptr->num_bytes_in_magazine -= SMALL_REGION_PAYLOAD_BYTES;
+ depot_ptr->mag_num_objects -= objects_in_use;
+
+ small_mag_ptr->mag_num_bytes_in_objects += bytes_inplay;
+ small_mag_ptr->num_bytes_in_magazine += SMALL_REGION_PAYLOAD_BYTES;
+ small_mag_ptr->mag_num_objects += objects_in_use;
+
+ // connect to magazine as last node
+ recirc_list_splice_last(rack, small_mag_ptr, node);
+
+ SZONE_MAGAZINE_PTR_UNLOCK(depot_ptr);
+
+ MAGMALLOC_DEPOTREGION(SMALL_SZONE_FROM_RACK(rack), (int)mag_index, (void *)sparse_region, SMALL_REGION_SIZE,
+ (int)BYTES_USED_FOR_SMALL_REGION(sparse_region)); // DTrace USDT Probe
+
+ return 1;
+}
+#endif // CONFIG_RECIRC_DEPOT
+
+#if CONFIG_MADVISE_PRESSURE_RELIEF
+void
+small_madvise_pressure_relief(rack_t *rack)
+{
+ mag_index_t mag_index;
+ magazine_t *small_depot_ptr = &rack->magazines[DEPOT_MAGAZINE_INDEX];
+
+ for (mag_index = 0; mag_index < rack->num_magazines; mag_index++) {
+ size_t index;
+ for (index = 0; index < rack->region_generation->num_regions_allocated; ++index) {
+ SZONE_LOCK(SMALL_SZONE_FROM_RACK(rack));
+
+ region_t small = rack->region_generation->hashed_regions[index];
+ if (!small || small == HASHRING_REGION_DEALLOCATED) {
+ SZONE_UNLOCK(SMALL_SZONE_FROM_RACK(rack));
+ continue;
+ }
+
+ magazine_t *mag_ptr = mag_lock_zine_for_region_trailer(rack->magazines,
+ REGION_TRAILER_FOR_SMALL_REGION(small),
+ MAGAZINE_INDEX_FOR_SMALL_REGION(small));
+ SZONE_UNLOCK(SMALL_SZONE_FROM_RACK(rack));
+
+ /* Ordering is important here, the magazine of a region may potentially change
+ * during mag_lock_zine_for_region_trailer, so src_mag_index must be taken
+ * after we've obtained the lock.
+ */
+ mag_index_t src_mag_index = MAGAZINE_INDEX_FOR_SMALL_REGION(small);
+
+ /* We can (and must) ignore magazines that are already in the recirc depot. */
+ if (src_mag_index == DEPOT_MAGAZINE_INDEX) {
+ SZONE_MAGAZINE_PTR_UNLOCK(mag_ptr);
+ continue;
+ }
+
+ if (small == mag_ptr->mag_last_region && (mag_ptr->mag_bytes_free_at_end || mag_ptr->mag_bytes_free_at_start)) {
+ small_finalize_region(rack, mag_ptr);
+ }
+
+ /* Because this region is currently in use, we can't safely madvise it while
+ * it's attached to the magazine. For this operation we have to remove it from
+ * the current mag, attach it to the depot and then madvise.
+ */
+
+ recirc_list_extract(rack, mag_ptr, REGION_TRAILER_FOR_SMALL_REGION(small));
+ int objects_in_use = small_free_detach_region(rack, mag_ptr, small);
+
+ SZONE_MAGAZINE_PTR_LOCK(small_depot_ptr);
+ MAGAZINE_INDEX_FOR_SMALL_REGION(small) = DEPOT_MAGAZINE_INDEX;
+ REGION_TRAILER_FOR_SMALL_REGION(small)->pinned_to_depot = 0;
+
+ size_t bytes_inplay = small_free_reattach_region(rack, small_depot_ptr, small);
+
+ /* Fix up the metadata of the target magazine while the region is in the depot. */
+ mag_ptr->mag_num_bytes_in_objects -= bytes_inplay;
+ mag_ptr->num_bytes_in_magazine -= SMALL_REGION_PAYLOAD_BYTES;
+ mag_ptr->mag_num_objects -= objects_in_use;
+
+ /* Now we can drop the magazine lock of the source mag. */
+ SZONE_MAGAZINE_PTR_UNLOCK(mag_ptr);
+
+ small_depot_ptr->mag_num_bytes_in_objects += bytes_inplay;
+ small_depot_ptr->num_bytes_in_magazine += SMALL_REGION_PAYLOAD_BYTES;
+ small_depot_ptr->mag_num_objects -= objects_in_use;
+
+ recirc_list_splice_last(rack, small_depot_ptr, REGION_TRAILER_FOR_SMALL_REGION(small));
+
+ /* Actually do the scan, done holding the depot lock, the call will drop the lock
+ * around the actual madvise syscalls.
+ */
+ small_free_scan_madvise_free(rack, small_depot_ptr, small);
+
+ /* Now the region is in the recirc depot, the next allocations to require more
+ * blocks will come along and take one of these regions back out of the depot.
+ * As OS X madvise's reuse on an per-region basis, we leave as many of these
+ * regions in the depot as possible after memory pressure.
+ */
+ SZONE_MAGAZINE_PTR_UNLOCK(small_depot_ptr);
+ }
+ }
+}
+#endif // CONFIG_MADVISE_PRESSURE_RELIEF
+
+#if CONFIG_AGGRESSIVE_MADVISE || CONFIG_RECIRC_DEPOT
+static MALLOC_INLINE void
+small_madvise_free_range_no_lock(rack_t *rack,
+ magazine_t *small_mag_ptr,
+ region_t region,
+ free_list_t freee,
+ msize_t fmsize,
+ void *headptr,
+ size_t headsize)
+{
+ void *ptr = small_free_list_get_ptr(freee);
+ region_trailer_t *node = REGION_TRAILER_FOR_SMALL_REGION(region);
+
+ // Lock on small_magazines[mag_index] is already held here.
+ // Calculate the first page in the coalesced block that would be safe to mark MADV_FREE
+ size_t free_header_size = sizeof(free_list_t) + sizeof(msize_t);
+
+ // If the free_list_t entry is out-of-line then we don't need to reserve any space
+ // at the start of the region.
+ if (small_is_oob_free_entry(freee)) {
+ free_header_size = 0;
+ }
+
+ uintptr_t safe_ptr = (uintptr_t)ptr + free_header_size;
+ uintptr_t round_safe = round_page_kernel(safe_ptr);
+
+ // Calculate the last page in the coalesced block that would be safe to mark MADV_FREE
+ uintptr_t safe_extent = (uintptr_t)ptr + SMALL_BYTES_FOR_MSIZE(fmsize);
+ uintptr_t trunc_extent = trunc_page_kernel(safe_extent);
+
+ // The newly freed block may complete a span of bytes that cover one or more pages. Mark the span with MADV_FREE.
+ if (round_safe < trunc_extent) { // Coalesced area covers a page (perhaps many)
+ // Extend the freed block by the free region header and tail sizes to include pages
+ // we may have coalesced that no longer host free region tails and headers.
+ // This may extend over in-use ranges, but the MIN/MAX clamping below will fix that up.
+ uintptr_t lo = trunc_page_kernel((uintptr_t)headptr);
+ uintptr_t hi = round_page_kernel((uintptr_t)headptr + headsize + free_header_size);
+
+ uintptr_t free_lo = MAX(round_safe, lo);
+ uintptr_t free_hi = MIN(trunc_extent, hi);
+
+ if (free_lo < free_hi) {
+ // Before unlocking, ensure that the metadata for the freed region
+ // makes it look not free but includes the length. This ensures that
+ // any code that inspects the metadata while we are unlocked sees
+ // a valid state and will not try to use or coalesce freed memory
+ // into it.
+ small_free_mark_unfree(rack, freee, fmsize);
+ small_free_list_remove_ptr_no_clear(rack, small_mag_ptr, freee, fmsize);
+ OSAtomicIncrement32Barrier(&(node->pinned_to_depot));
+ SZONE_MAGAZINE_PTR_UNLOCK(small_mag_ptr);
+ mvm_madvise_free(rack, region, free_lo, free_hi, &rack->last_madvise, rack->debug_flags & MALLOC_DO_SCRIBBLE);
+ SZONE_MAGAZINE_PTR_LOCK(small_mag_ptr);
+ OSAtomicDecrement32Barrier(&(node->pinned_to_depot));
+ small_free_list_add_ptr(rack, small_mag_ptr, ptr, fmsize);
+ }
+ }
+}
+#endif // CONFIG_AGGRESSIVE_MADVISE || CONFIG_RECIRC_DEPOT
+
+#if CONFIG_RECIRC_DEPOT
+static region_t
+small_free_try_depot_unmap_no_lock(rack_t *rack, magazine_t *depot_ptr, region_trailer_t *node)
+{
+ if (0 < node->bytes_used || 0 < node->pinned_to_depot || depot_ptr->recirculation_entries < recirc_retained_regions) {
+ return NULL;
+ }
+
+ // disconnect first node from Depot
+ recirc_list_extract(rack, depot_ptr, node);
+
+ // Iterate the region pulling its free entries off the (locked) Depot's free list
+ region_t sparse_region = SMALL_REGION_FOR_PTR(node);
+ int objects_in_use = small_free_detach_region(rack, depot_ptr, sparse_region);
+
+ if (0 == objects_in_use) {
+ // Invalidate the hash table entry for this region with HASHRING_REGION_DEALLOCATED.
+ // Using HASHRING_REGION_DEALLOCATED preserves the collision chain, using HASHRING_OPEN_ENTRY (0) would not.
+ rgnhdl_t pSlot = hash_lookup_region_no_lock(rack->region_generation->hashed_regions,
+ rack->region_generation->num_regions_allocated,
+ rack->region_generation->num_regions_allocated_shift,
+ sparse_region);
+ if (NULL == pSlot) {
+ malloc_zone_error(rack->debug_flags, true, "small_free_try_depot_unmap_no_lock hash lookup failed: %p\n", sparse_region);
+ return NULL;
+ }
+ *pSlot = HASHRING_REGION_DEALLOCATED;
+ depot_ptr->num_bytes_in_magazine -= SMALL_REGION_PAYLOAD_BYTES;
+ // Atomically increment num_regions_dealloc
+#ifdef __LP64___
+ OSAtomicIncrement64(&rack->num_regions_dealloc);
+#else
+ OSAtomicIncrement32((int32_t *)&rack->num_regions_dealloc);
+#endif
+
+ // Caller will transfer ownership of the region back to the OS with no locks held
+ MAGMALLOC_DEALLOCREGION(SMALL_SZONE_FROM_RACK(rack), (void *)sparse_region, (int)SMALL_REGION_SIZE); // DTrace USDT Probe
+ return sparse_region;
+
+ } else {
+ malloc_zone_error(rack->debug_flags, true, "small_free_try_depot_unmap_no_lock objects_in_use not zero: %d\n", objects_in_use);
+ return NULL;
+ }
+}
+
+static boolean_t
+small_free_do_recirc_to_depot(rack_t *rack, magazine_t *small_mag_ptr, mag_index_t mag_index)
+{
+ // The entire magazine crossed the "emptiness threshold". Transfer a region
+ // from this magazine to the Depot. Choose a region that itself has crossed the emptiness threshold (i.e
+ // is at least fraction "f" empty.) Such a region will be marked "suitable" on the recirculation list.
+ region_trailer_t *node = small_mag_ptr->firstNode;
+
+ while (node && (!node->recirc_suitable || node->pinned_to_depot)) {
+ node = node->next;
+ }
+
+ if (NULL == node) {
+#if DEBUG_MALLOC
+ malloc_report(ASL_LEVEL_ERR, "*** small_free_do_recirc_to_depot end of list\n");
+#endif
+ return TRUE; // Caller must SZONE_MAGAZINE_PTR_UNLOCK(small_mag_ptr);
+ }
+
+ region_t sparse_region = SMALL_REGION_FOR_PTR(node);
+
+ // Deal with unclaimed memory -- mag_bytes_free_at_end or mag_bytes_free_at start
+ if (sparse_region == small_mag_ptr->mag_last_region &&
+ (small_mag_ptr->mag_bytes_free_at_end || small_mag_ptr->mag_bytes_free_at_start)) {
+ small_finalize_region(rack, small_mag_ptr);
+ }
+
+ // disconnect "suitable" node from magazine
+ recirc_list_extract(rack, small_mag_ptr, node);
+
+ // Iterate the region pulling its free entries off its (locked) magazine's free list
+ int objects_in_use = small_free_detach_region(rack, small_mag_ptr, sparse_region);
+ magazine_t *depot_ptr = &(rack->magazines[DEPOT_MAGAZINE_INDEX]);
+
+ // hand over the region to the (locked) Depot
+ SZONE_MAGAZINE_PTR_LOCK(depot_ptr);
+ // this will cause small_free_list_add_ptr called by small_free_reattach_region to use
+ // the depot as its target magazine, rather than magazine formerly associated with sparse_region
+ MAGAZINE_INDEX_FOR_SMALL_REGION(sparse_region) = DEPOT_MAGAZINE_INDEX;
+ node->pinned_to_depot = 0;
+
+ // Iterate the region putting its free entries on Depot's free list
+ size_t bytes_inplay = small_free_reattach_region(rack, depot_ptr, sparse_region);
+
+ small_mag_ptr->mag_num_bytes_in_objects -= bytes_inplay;
+ small_mag_ptr->num_bytes_in_magazine -= SMALL_REGION_PAYLOAD_BYTES;
+ small_mag_ptr->mag_num_objects -= objects_in_use;
+
+ SZONE_MAGAZINE_PTR_UNLOCK(small_mag_ptr); // Unlock the originating magazine
+
+ depot_ptr->mag_num_bytes_in_objects += bytes_inplay;
+ depot_ptr->num_bytes_in_magazine += SMALL_REGION_PAYLOAD_BYTES;
+ depot_ptr->mag_num_objects += objects_in_use;
+
+ // connect to Depot as last node
+ recirc_list_splice_last(rack, depot_ptr, node);
+
+ MAGMALLOC_RECIRCREGION(SMALL_SZONE_FROM_RACK(rack), (int)mag_index, (void *)sparse_region, SMALL_REGION_SIZE,
+ (int)BYTES_USED_FOR_SMALL_REGION(sparse_region)); // DTrace USDT Probe
+
+#if !CONFIG_AGGRESSIVE_MADVISE
+ // Mark free'd dirty pages with MADV_FREE to reduce memory pressure
+ small_free_scan_madvise_free(rack, depot_ptr, sparse_region);
+#endif
+
+ // If the region is entirely empty vm_deallocate() it outside the depot lock
+ region_t r_dealloc = small_free_try_depot_unmap_no_lock(rack, depot_ptr, node);
+ SZONE_MAGAZINE_PTR_UNLOCK(depot_ptr);
+ if (r_dealloc) {
+ mvm_deallocate_pages(r_dealloc, SMALL_REGION_SIZE, 0);
+ }
+ return FALSE; // Caller need not unlock the originating magazine
+}
+
+static MALLOC_INLINE boolean_t
+small_free_try_recirc_to_depot(rack_t *rack,
+ magazine_t *small_mag_ptr,
+ mag_index_t mag_index,
+ region_t region,
+ free_list_t freee,
+ msize_t msize,
+ void *headptr,
+ size_t headsize)
+{
+ region_trailer_t *node = REGION_TRAILER_FOR_SMALL_REGION(region);
+ size_t bytes_used = node->bytes_used;
+
+ /* FIXME: Would Uniprocessor benefit from recirc and MADV_FREE? */
+ if (rack->num_magazines == 1) { // Uniprocessor, single magazine, so no recirculation necessary
+ /* NOTHING */
+ return TRUE; // Caller must do SZONE_MAGAZINE_PTR_UNLOCK(tiny_mag_ptr)
+ } else if (DEPOT_MAGAZINE_INDEX != mag_index) {
+ // Emptiness discriminant
+ if (small_region_below_recirc_threshold(region)) {
+ /* Region has crossed threshold from density to sparsity. Mark it "suitable" on the
+ * recirculation candidates list. */
+ node->recirc_suitable = TRUE;
+ } else {
+ /* After this free, we've found the region is still dense, so it must have been even more so before
+ * the free. That implies the region is already correctly marked. Do nothing. */
+ }
+
+ // Has the entire magazine crossed the "emptiness threshold"? If so, transfer a region
+ // from this magazine to the Depot. Choose a region that itself has crossed the emptiness threshold (i.e
+ // is at least fraction "f" empty.) Such a region will be marked "suitable" on the recirculation list.
+ if (small_magazine_below_recirc_threshold(small_mag_ptr)) {
+ return small_free_do_recirc_to_depot(rack, small_mag_ptr, mag_index);
+ }
+ } else {
+#if !CONFIG_AGGRESSIVE_MADVISE
+ // We are free'ing into the depot, so madvise as we do so unless we were madvising every incoming
+ // allocation anyway.
+ small_madvise_free_range_no_lock(rack, small_mag_ptr, region, freee, msize, headptr, headsize);
+#endif
+
+ if (0 < bytes_used || 0 < node->pinned_to_depot) {
+ /* Depot'd region is still live. Leave it in place on the Depot's recirculation list
+ * so as to avoid thrashing between the Depot's free list and a magazines's free list
+ * with detach_region/reattach_region */
+ } else {
+ /* Depot'd region is just now empty. Consider return to OS. */
+ region_t r_dealloc = small_free_try_depot_unmap_no_lock(rack, small_mag_ptr, node);
+ SZONE_MAGAZINE_PTR_UNLOCK(small_mag_ptr);
+ if (r_dealloc) {
+ mvm_deallocate_pages(r_dealloc, SMALL_REGION_SIZE, 0);
+ }
+ return FALSE; // Caller need not unlock
+ }
+ }
+ return TRUE; // Caller must do SZONE_MAGAZINE_PTR_UNLOCK(tiny_mag_ptr)
+}
+#endif // CONFIG_RECIRC_DEPOT
+
+static MALLOC_INLINE boolean_t
+small_free_no_lock(rack_t *rack, magazine_t *small_mag_ptr, mag_index_t mag_index, region_t region, void *ptr, msize_t msize)
+{
+ msize_t *meta_headers = SMALL_META_HEADER_FOR_PTR(ptr);
+ unsigned index = SMALL_META_INDEX_FOR_PTR(ptr);
+ size_t original_size = SMALL_BYTES_FOR_MSIZE(msize);
+ unsigned char *next_block = ((unsigned char *)ptr + original_size);
+ msize_t next_index = index + msize;
+
+ MALLOC_TRACE(TRACE_small_free, (uintptr_t)rack, (uintptr_t)small_mag_ptr, (uintptr_t)ptr, SMALL_BYTES_FOR_MSIZE(msize));
+
+#if CONFIG_AGGRESSIVE_MADVISE || CONFIG_RECIRC_DEPOT
+ void *original_ptr = ptr;
+#endif // CONFIG_AGGRESSIVE_MADVISE || CONFIG_RECIRC_DEPOT
+
+#if DEBUG_MALLOC
+ if (LOG(szone, ptr)) {
+ malloc_report(ASL_LEVEL_ERR, "in small_free_no_lock(), ptr=%p, msize=%d\n", ptr, msize);
+ }
+ if (!msize) {
+ malloc_zone_error(rack->debug_flags, true, "trying to free small block that is too small in small_free_no_lock(), ptr=%p, msize=%d\n",
+ ptr, msize);
+ }
+#endif
+
+ // Check that the region cookie is intact.
+ region_trailer_t *trailer = REGION_TRAILER_FOR_SMALL_REGION(region);
+ region_check_cookie(region, trailer);
+
+ // We try to coalesce this block with the preceeding one
+ if (index > 0 && (meta_headers[index - 1] & SMALL_IS_FREE)) {
+ msize_t previous_msize = meta_headers[index - 1] & ~SMALL_IS_FREE;
+ grain_t previous_index = index - previous_msize;
+
+ // Check if the metadata for the start of the block is also free.
+ if (meta_headers[previous_index] == (previous_msize | SMALL_IS_FREE)) {
+ void *previous_ptr = (void *)((uintptr_t)ptr - SMALL_BYTES_FOR_MSIZE(previous_msize));
+ free_list_t previous = small_free_list_find_by_ptr(rack, small_mag_ptr, previous_ptr, previous_msize);
+ small_free_list_remove_ptr(rack, small_mag_ptr, previous, previous_msize);
+ ptr = previous_ptr;
+ small_meta_header_set_middle(meta_headers, index); // This block is now a middle block.
+ msize += previous_msize;
+ index -= previous_msize;
+ } else {
+ _os_set_crash_log_message("small free list metadata inconsistency (headers[previous] != previous size)");
+ __builtin_trap();
+ }
+ }
+
+ // Try to coalesce with this block with the next block
+ if ((next_block < SMALL_REGION_END(region)) && (meta_headers[next_index] & SMALL_IS_FREE)) {
+ msize_t next_msize = meta_headers[next_index] & ~SMALL_IS_FREE;
+ free_list_t next = small_free_list_find_by_ptr(rack, small_mag_ptr, next_block, next_msize);
+ small_free_list_remove_ptr(rack, small_mag_ptr, next, next_msize);
+ msize += next_msize;
+ }
+
+ if (rack->debug_flags & MALLOC_DO_SCRIBBLE) {
+ if (!msize) {
+ malloc_zone_error(rack->debug_flags, true, "incorrect size information for %p - block header was damaged\n", ptr);
+ } else {
+ memset(ptr, SCRABBLE_BYTE, SMALL_BYTES_FOR_MSIZE(msize));
+ }
+ }
+
+ free_list_t freee = small_free_list_add_ptr(rack, small_mag_ptr, ptr, msize);
+
+ // use original_size and not msize to avoid double counting the coalesced blocks
+ small_mag_ptr->mag_num_bytes_in_objects -= original_size;
+
+ // Update this region's bytes in use count
+ size_t bytes_used = trailer->bytes_used - original_size;
+ trailer->bytes_used = (unsigned int)bytes_used;
+
+#if CONFIG_AGGRESSIVE_MADVISE
+ small_madvise_free_range_no_lock(rack, small_mag_ptr, region, freee, msize, original_ptr, original_size);
+#endif
+
+ // Caller must do SZONE_MAGAZINE_PTR_UNLOCK(tiny_mag_ptr) if this function
+ // returns TRUE.
+ boolean_t needs_unlock = TRUE;
+
+#if CONFIG_RECIRC_DEPOT
+ needs_unlock = small_free_try_recirc_to_depot(rack, small_mag_ptr, mag_index, region, freee, msize, original_ptr, original_size);
+#endif // CONFIG_RECIRC_DEPOT
+ return needs_unlock;
+}
+
+// Allocates from the last region or a freshly allocated region
+static void *
+small_malloc_from_region_no_lock(rack_t *rack,
+ magazine_t *small_mag_ptr,
+ mag_index_t mag_index,
+ msize_t msize,
+ void *aligned_address)
+{
+ void *ptr;
+
+ // Before anything we transform the mag_bytes_free_at_end or mag_bytes_free_at_start - if any - to a regular free block
+ /* FIXME: last_block needs to be coalesced with previous entry if free, <rdar://5462322> */
+ if (small_mag_ptr->mag_bytes_free_at_end || small_mag_ptr->mag_bytes_free_at_start) {
+ small_finalize_region(rack, small_mag_ptr);
+ }
+
+ // Tag the region at "aligned_address" as belonging to us,
+ // and so put it under the protection of the magazine lock we are holding.
+ // Do this before advertising "aligned_address" on the hash ring(!)
+ MAGAZINE_INDEX_FOR_SMALL_REGION(aligned_address) = mag_index;
+
+ // Insert the new region into the hash ring
+ rack_region_insert(rack, (region_t)aligned_address);
+
+ small_mag_ptr->mag_last_region = aligned_address;
+ BYTES_USED_FOR_SMALL_REGION(aligned_address) = SMALL_BYTES_FOR_MSIZE(msize);
+
+#if CONFIG_ASLR_INTERNAL
+ int offset_msize = malloc_entropy[1] & SMALL_ENTROPY_MASK;
+#if DEBUG_MALLOC
+ if (getenv("MallocASLRForce")) {
+ offset_msize = strtol(getenv("MallocASLRForce"), NULL, 0) & SMALL_ENTROPY_MASK;
+ }
+ if (getenv("MallocASLRPrint")) {
+ malloc_report(ASL_LEVEL_INFO, "Region: %p offset: %d\n", aligned_address, offset_msize);
+ }
+#endif
+#else
+ int offset_msize = 0;
+#endif
+ ptr = (void *)((uintptr_t)aligned_address + SMALL_BYTES_FOR_MSIZE(offset_msize));
+ small_meta_header_set_in_use(SMALL_META_HEADER_FOR_PTR(ptr), offset_msize, msize);
+ small_mag_ptr->mag_num_objects++;
+ small_mag_ptr->mag_num_bytes_in_objects += SMALL_BYTES_FOR_MSIZE(msize);
+ small_mag_ptr->num_bytes_in_magazine += SMALL_REGION_PAYLOAD_BYTES;
+
+ // add a big free block at the end
+ small_meta_header_set_in_use(SMALL_META_HEADER_FOR_PTR(ptr), offset_msize + msize, NUM_SMALL_BLOCKS - msize - offset_msize);
+ small_mag_ptr->mag_bytes_free_at_end = SMALL_BYTES_FOR_MSIZE(NUM_SMALL_BLOCKS - msize - offset_msize);
+
+#if CONFIG_ASLR_INTERNAL
+ // add a big free block at the start
+ small_mag_ptr->mag_bytes_free_at_start = SMALL_BYTES_FOR_MSIZE(offset_msize);
+ if (offset_msize) {
+ small_meta_header_set_in_use(SMALL_META_HEADER_FOR_PTR(ptr), 0, offset_msize);
+ }
+#else
+ small_mag_ptr->mag_bytes_free_at_start = 0;
+#endif
+
+ // connect to magazine as last node
+ recirc_list_splice_last(rack, small_mag_ptr, REGION_TRAILER_FOR_SMALL_REGION(aligned_address));
+
+ return ptr;
+}
+
+void *
+small_memalign(szone_t *szone, size_t alignment, size_t size, size_t span)
+{
+ msize_t mspan = SMALL_MSIZE_FOR_BYTES(span + SMALL_QUANTUM - 1);
+ void *p = small_malloc_should_clear(&szone->small_rack, mspan, 0);
+
+ if (NULL == p) {
+ return NULL;
+ }
+
+ size_t offset = ((uintptr_t)p) & (alignment - 1); // p % alignment
+ size_t pad = (0 == offset) ? 0 : alignment - offset; // p + pad achieves desired alignment
+
+ msize_t msize = SMALL_MSIZE_FOR_BYTES(size + SMALL_QUANTUM - 1);
+ msize_t mpad = SMALL_MSIZE_FOR_BYTES(pad + SMALL_QUANTUM - 1);
+ msize_t mwaste = mspan - msize - mpad; // excess blocks
+
+ if (mpad > 0) {
+ void *q = (void *)(((uintptr_t)p) + pad);
+
+ // Mark q as block header and in-use, thus creating two blocks.
+ magazine_t *small_mag_ptr = mag_lock_zine_for_region_trailer(szone->small_rack.magazines,
+ REGION_TRAILER_FOR_SMALL_REGION(SMALL_REGION_FOR_PTR(p)),
+ MAGAZINE_INDEX_FOR_SMALL_REGION(SMALL_REGION_FOR_PTR(p)));
+ small_meta_header_set_in_use(SMALL_META_HEADER_FOR_PTR(p), SMALL_META_INDEX_FOR_PTR(p), mpad);
+ small_meta_header_set_in_use(SMALL_META_HEADER_FOR_PTR(q), SMALL_META_INDEX_FOR_PTR(q), msize + mwaste);
+ small_mag_ptr->mag_num_objects++;
+ SZONE_MAGAZINE_PTR_UNLOCK(small_mag_ptr);
+
+ // Give up mpad blocks beginning at p to the small free list
+ free_small(&szone->small_rack, p, SMALL_REGION_FOR_PTR(p), SMALL_BYTES_FOR_MSIZE(mpad));
+
+ p = q; // advance p to the desired alignment
+ }
+ if (mwaste > 0) {
+ void *q = (void *)(((uintptr_t)p) + SMALL_BYTES_FOR_MSIZE(msize));
+ // Mark q as block header and in-use, thus creating two blocks.
+ magazine_t *small_mag_ptr = mag_lock_zine_for_region_trailer(szone->small_rack.magazines,
+ REGION_TRAILER_FOR_SMALL_REGION(SMALL_REGION_FOR_PTR(p)),
+ MAGAZINE_INDEX_FOR_SMALL_REGION(SMALL_REGION_FOR_PTR(p)));
+ small_meta_header_set_in_use(SMALL_META_HEADER_FOR_PTR(p), SMALL_META_INDEX_FOR_PTR(p), msize);
+ small_meta_header_set_in_use(SMALL_META_HEADER_FOR_PTR(q), SMALL_META_INDEX_FOR_PTR(q), mwaste);
+ small_mag_ptr->mag_num_objects++;
+ SZONE_MAGAZINE_PTR_UNLOCK(small_mag_ptr);
+
+ // Give up mwaste blocks beginning at q to the small free list
+ free_small(&szone->small_rack, q, SMALL_REGION_FOR_PTR(q), SMALL_BYTES_FOR_MSIZE(mwaste));
+ }
+
+ return p; // p has the desired size and alignment, and can later be free()'d
+}
+
+boolean_t
+small_claimed_address(rack_t *rack, void *ptr)
+{
+ region_t r = small_region_for_ptr_no_lock(rack, ptr);
+ return r && ptr < (void *)SMALL_REGION_END(r);
+}
+
+void *
+small_try_shrink_in_place(rack_t *rack, void *ptr, size_t old_size, size_t new_good_size)
+{
+ msize_t new_msize = SMALL_MSIZE_FOR_BYTES(new_good_size);
+ msize_t mshrinkage = SMALL_MSIZE_FOR_BYTES(old_size) - new_msize;
+
+ if (mshrinkage) {
+ void *q = (void *)((uintptr_t)ptr + SMALL_BYTES_FOR_MSIZE(new_msize));
+ magazine_t *small_mag_ptr = mag_lock_zine_for_region_trailer(rack->magazines,
+ REGION_TRAILER_FOR_SMALL_REGION(SMALL_REGION_FOR_PTR(ptr)),
+ MAGAZINE_INDEX_FOR_SMALL_REGION(SMALL_REGION_FOR_PTR(ptr)));
+
+ // Mark q as block header and in-use, thus creating two blocks.
+ small_meta_header_set_in_use(SMALL_META_HEADER_FOR_PTR(ptr), SMALL_META_INDEX_FOR_PTR(ptr), new_msize);
+ small_meta_header_set_in_use(SMALL_META_HEADER_FOR_PTR(q), SMALL_META_INDEX_FOR_PTR(q), mshrinkage);
+ small_mag_ptr->mag_num_objects++;
+
+ SZONE_MAGAZINE_PTR_UNLOCK(small_mag_ptr);
+ free_small(rack, q, SMALL_REGION_FOR_PTR(q), 0);
+ }
+
+ return ptr;
+}
+
+boolean_t
+small_try_realloc_in_place(rack_t *rack, void *ptr, size_t old_size, size_t new_size)
+{
+ // returns 1 on success
+ msize_t *meta_headers = SMALL_META_HEADER_FOR_PTR(ptr);
+ unsigned index;
+ msize_t old_msize, new_msize;
+ unsigned next_index;
+ void *next_block;
+ msize_t next_msize_and_free;
+ boolean_t is_free;
+ msize_t next_msize, leftover_msize;
+ void *leftover;
+
+ index = SMALL_META_INDEX_FOR_PTR(ptr);
+ old_msize = SMALL_MSIZE_FOR_BYTES(old_size);
+ new_msize = SMALL_MSIZE_FOR_BYTES(new_size + SMALL_QUANTUM - 1);
+ next_index = index + old_msize;
+
+ if (next_index >= NUM_SMALL_BLOCKS) {
+ return 0;
+ }
+ next_block = (char *)ptr + old_size;
+
+#if DEBUG_MALLOC
+ if ((uintptr_t)next_block & (SMALL_QUANTUM - 1)) {
+ malloc_zone_error(rack->debug_flags, true, "internal invariant broken in realloc(next_block) for %p\n", next_block);
+ }
+ if (meta_headers[index] != old_msize) {
+ malloc_report(ASL_LEVEL_ERR, "*** small_try_realloc_in_place incorrect old %d %d\n", meta_headers[index], old_msize);
+ }
+#endif
+
+ magazine_t *small_mag_ptr = mag_lock_zine_for_region_trailer(rack->magazines,
+ REGION_TRAILER_FOR_SMALL_REGION(SMALL_REGION_FOR_PTR(ptr)),
+ MAGAZINE_INDEX_FOR_SMALL_REGION(SMALL_REGION_FOR_PTR(ptr)));
+ if (DEPOT_MAGAZINE_INDEX == MAGAZINE_INDEX_FOR_SMALL_REGION(SMALL_REGION_FOR_PTR(ptr))) {
+ SZONE_MAGAZINE_PTR_UNLOCK(small_mag_ptr);
+ return 0;
+ }
+
+ msize_t coalesced_msize = new_msize - old_msize;
+#if CONFIG_SMALL_CACHE
+ void *last_free_ptr = small_mag_ptr->mag_last_free;
+ msize_t last_free_msize = small_mag_ptr->mag_last_free_msize;
+ if (last_free_ptr == next_block && old_msize + last_free_msize >= new_msize) {
+ /*
+ * There is a block in mag_last_free and it's immediately after
+ * this block and it's large enough. We can use some or all of it.
+ */
+ leftover_msize = last_free_msize - coalesced_msize;
+ if (leftover_msize) {
+ small_mag_ptr->mag_last_free_msize -= coalesced_msize;
+ small_mag_ptr->mag_last_free += new_size - old_size;
+ // The block in mag_last_free is still marked as header and in-use, so copy that
+ // state to the block that remains. The state for the block that we're going to
+ // use is adjusted by the small_meta_header_set_middle() call below.
+ small_meta_header_set_in_use(meta_headers, index + new_msize, leftover_msize);
+ } else {
+ // Using the whole block.
+ small_mag_ptr->mag_last_free = NULL;
+ small_mag_ptr->mag_last_free_msize = 0;
+ small_mag_ptr->mag_last_free_rgn = NULL;
+ }
+ small_meta_header_set_in_use(meta_headers, index, new_msize);
+ small_meta_header_set_middle(meta_headers, next_index);
+ } else {
+#endif // CONFIG_SMALL_CACHE
+ /*
+ * Try to expand into unused space immediately after this block.
+ */
+ msize_t unused_msize = SMALL_MSIZE_FOR_BYTES(small_mag_ptr->mag_bytes_free_at_end);
+ void *unused_start = SMALL_REGION_END(SMALL_REGION_FOR_PTR(ptr)) - small_mag_ptr->mag_bytes_free_at_end;
+ if (small_mag_ptr->mag_last_region == SMALL_REGION_FOR_PTR(ptr)
+ && coalesced_msize < unused_msize && unused_start == ptr + old_size) {
+ // Extend the in-use for this block to the new size
+ small_meta_header_set_in_use(meta_headers, index, new_msize);
+
+ // Clear the in-use size for the start of the area we extended into
+ small_meta_header_set_middle(meta_headers, next_index);
+
+ // Reduce mag_bytes_free_at_end and update its in-use size.
+ small_mag_ptr->mag_bytes_free_at_end -= SMALL_BYTES_FOR_MSIZE(coalesced_msize);
+ small_meta_header_set_in_use(meta_headers, index + new_msize, SMALL_MSIZE_FOR_BYTES(small_mag_ptr->mag_bytes_free_at_end));
+ } else {
+ /*
+ * Look for a free block immediately afterwards. If it's large enough, we can consume (part of)
+ * it.
+ */
+ next_msize_and_free = meta_headers[next_index];
+ is_free = next_msize_and_free & SMALL_IS_FREE;
+ if (!is_free) {
+ SZONE_MAGAZINE_PTR_UNLOCK(small_mag_ptr);
+ return 0; // next_block is in use;
+ }
+
+ next_msize = next_msize_and_free & ~SMALL_IS_FREE;
+ if (old_msize + next_msize < new_msize) {
+ SZONE_MAGAZINE_PTR_UNLOCK(small_mag_ptr);
+ return 0; // even with next block, not enough
+ }
+
+ // The following block is big enough; pull it from its freelist and chop off enough to satisfy
+ // our needs.
+ free_list_t freee = small_free_list_find_by_ptr(rack, small_mag_ptr, next_block, next_msize);
+ small_free_list_remove_ptr(rack, small_mag_ptr, freee, next_msize);
+ small_meta_header_set_middle(meta_headers, next_index);
+ leftover_msize = old_msize + next_msize - new_msize;
+ if (leftover_msize) {
+ /* there's some left, so put the remainder back */
+ leftover = (unsigned char *)ptr + SMALL_BYTES_FOR_MSIZE(new_msize);
+ small_free_list_add_ptr(rack, small_mag_ptr, leftover, leftover_msize);
+ }
+ small_meta_header_set_in_use(meta_headers, index, new_msize);
+ }
+#if CONFIG_SMALL_CACHE
+ }
+#endif // CONFIG_SMALL_CACHE
+#if DEBUG_MALLOC
+ if (SMALL_BYTES_FOR_MSIZE(new_msize) > szone->large_threshold) {
+ malloc_report(ASL_LEVEL_ERR, "*** realloc in place for %p exceeded msize=%d\n", new_msize);
+ }
+
+ if (LOG(szone, ptr)) {
+ malloc_report(ASL_LEVEL_INFO, "in small_try_realloc_in_place(), ptr=%p, msize=%d\n", ptr, *SMALL_METADATA_FOR_PTR(ptr));
+ }
+#endif
+ small_mag_ptr->mag_num_bytes_in_objects += SMALL_BYTES_FOR_MSIZE(new_msize - old_msize);
+
+ // Update this region's bytes in use count
+ region_trailer_t *node = REGION_TRAILER_FOR_SMALL_REGION(SMALL_REGION_FOR_PTR(ptr));
+ size_t bytes_used = node->bytes_used + SMALL_BYTES_FOR_MSIZE(new_msize - old_msize);
+ node->bytes_used = (unsigned int)bytes_used;
+
+ // Emptiness discriminant
+ if (bytes_used < DENSITY_THRESHOLD(SMALL_REGION_PAYLOAD_BYTES)) {
+ /* After this reallocation the region is still sparse, so it must have been even more so before
+ * the reallocation. That implies the region is already correctly marked. Do nothing. */
+ } else {
+ /* Region has crossed threshold from sparsity to density. Mark it not "suitable" on the
+ * recirculation candidates list. */
+ node->recirc_suitable = FALSE;
+ }
+
+ SZONE_MAGAZINE_PTR_UNLOCK(small_mag_ptr);
+ CHECK(szone, __PRETTY_FUNCTION__);
+ return 1;
+}
+
+static char *small_check_fail_msg = "check: incorrect small region ";
+
+#define SMALL_CHECK_FAIL(fmt, ...) \
+ malloc_zone_check_fail(small_check_fail_msg, \
+ "%ld, counter=%d\n" fmt, region_index, counter, __VA_ARGS__);
+
+boolean_t
+small_check_region(rack_t *rack, region_t region, size_t region_index,
+ unsigned counter)
+{
+ unsigned char *ptr = SMALL_REGION_ADDRESS(region);
+ msize_t *meta_headers = SMALL_META_HEADER_FOR_PTR(ptr);
+ unsigned char *region_end = SMALL_REGION_END(region);
+ msize_t prev_free = 0;
+ unsigned index;
+ msize_t msize_and_free;
+ msize_t msize;
+ free_list_t free_head, previous, next;
+ msize_t *follower;
+ mag_index_t mag_index = MAGAZINE_INDEX_FOR_SMALL_REGION(SMALL_REGION_FOR_PTR(ptr));
+ magazine_t *small_mag_ptr = &(rack->magazines[mag_index]);
+
+ // Assumes locked
+ CHECK_MAGAZINE_PTR_LOCKED(szone, small_mag_ptr, __PRETTY_FUNCTION__);
+
+ if (region == small_mag_ptr->mag_last_region) {
+ ptr += small_mag_ptr->mag_bytes_free_at_start;
+ region_end -= small_mag_ptr->mag_bytes_free_at_end;
+ }
+
+ while (ptr < region_end) {
+ index = SMALL_META_INDEX_FOR_PTR(ptr);
+ msize_and_free = meta_headers[index];
+ if (!(msize_and_free & SMALL_IS_FREE)) {
+ // block is in use
+ msize = msize_and_free;
+ if (!msize) {
+ SMALL_CHECK_FAIL("*** invariant broken: null msize ptr=%p num_small_regions=%d end=%p\n", ptr,
+ (int)rack->num_regions, region_end);
+ return 0;
+ }
+#if !CONFIG_RELAXED_INVARIANT_CHECKS
+ if (SMALL_BYTES_FOR_MSIZE(msize) > szone->large_threshold) {
+ SMALL_CHECK_FAIL("*** invariant broken for %p this small msize=%d - size is too large\n", ptr, msize_and_free);
+ return 0;
+ }
+#endif // CONFIG_RELAXED_INVARIANT_CHECKS
+ ptr += SMALL_BYTES_FOR_MSIZE(msize);
+ prev_free = 0;
+ } else {
+ // free pointer
+ msize = msize_and_free & ~SMALL_IS_FREE;
+ free_head = (free_list_t){ .p = ptr };
+ follower = (msize_t *)FOLLOWING_SMALL_PTR(ptr, msize);
+ if (!msize) {
+ SMALL_CHECK_FAIL("*** invariant broken for free block %p this msize=%d\n", ptr, msize);
+ return 0;
+ }
+#if !CONFIG_RELAXED_INVARIANT_CHECKS
+ if (prev_free) {
+ SMALL_CHECK_FAIL("*** invariant broken for %p (2 free in a row)\n", ptr);
+ return 0;
+ }
+#endif
+
+ // <rdar://problem/24680189> check for possible OOB entry if needed
+ if (small_needs_oob_free_entry(ptr, msize)) {
+ oob_free_entry_t oob = small_oob_free_find_ptr(ptr, msize);
+ if (oob) {
+ free_head.oob = oob;
+ }
+ }
+
+ previous = small_free_list_get_previous(rack, free_head);
+ next = small_free_list_get_next(rack, free_head);
+ if (previous.p && !SMALL_PTR_IS_FREE(small_free_list_get_ptr(previous))) {
+ SMALL_CHECK_FAIL("*** invariant broken for %p (previous %p is not a free pointer)\n", ptr, small_free_list_get_ptr(previous));
+ return 0;
+ }
+ if (next.p && !SMALL_PTR_IS_FREE(small_free_list_get_ptr(next))) {
+ SMALL_CHECK_FAIL("*** invariant broken for %p (next %p is not a free pointer)\n", ptr, small_free_list_get_ptr(next));
+ return 0;
+ }
+ if (SMALL_PREVIOUS_MSIZE(follower) != msize) {
+ SMALL_CHECK_FAIL("*** invariant broken for small free %p followed by %p in region [%p-%p] "
+ "(end marker incorrect) should be %d; in fact %d\n",
+ ptr, follower, SMALL_REGION_ADDRESS(region), region_end, msize, SMALL_PREVIOUS_MSIZE(follower));
+ return 0;
+ }
+ ptr = (unsigned char *)follower;
+ prev_free = SMALL_IS_FREE;
+ }
+ }
+ return 1;
+}
+
+kern_return_t
+small_in_use_enumerator(task_t task,
+ void *context,
+ unsigned type_mask,
+ szone_t *szone,
+ memory_reader_t reader,
+ vm_range_recorder_t recorder)
+{
+ size_t num_regions;
+ size_t index;
+ region_t *regions;
+ vm_range_t buffer[MAX_RECORDER_BUFFER];
+ unsigned count = 0;
+ kern_return_t err;
+ region_t region;
+ vm_range_t range;
+ vm_range_t admin_range;
+ vm_range_t ptr_range;
+ unsigned char *mapped_region;
+ msize_t *block_header;
+ unsigned block_index;
+ unsigned block_limit;
+ msize_t msize_and_free;
+ msize_t msize;
+ magazine_t *small_mag_base = NULL;
+
+ region_hash_generation_t *srg_ptr;
+ err = reader(task, (vm_address_t)szone->small_rack.region_generation, sizeof(region_hash_generation_t), (void **)&srg_ptr);
+ if (err) {
+ return err;
+ }
+
+ num_regions = srg_ptr->num_regions_allocated;
+ err = reader(task, (vm_address_t)srg_ptr->hashed_regions, sizeof(region_t) * num_regions, (void **)®ions);
+ if (err) {
+ return err;
+ }
+
+ if (type_mask & MALLOC_PTR_IN_USE_RANGE_TYPE) {
+ // Map in all active magazines. Do this outside the iteration over regions.
+ err = reader(task, (vm_address_t)(szone->small_rack.magazines), szone->small_rack.num_magazines * sizeof(magazine_t),
+ (void **)&small_mag_base);
+ if (err) {
+ return err;
+ }
+ }
+
+ for (index = 0; index < num_regions; ++index) {
+ region = regions[index];
+ if (HASHRING_OPEN_ENTRY != region && HASHRING_REGION_DEALLOCATED != region) {
+ range.address = (vm_address_t)SMALL_REGION_ADDRESS(region);
+ range.size = SMALL_REGION_SIZE;
+ if (type_mask & MALLOC_ADMIN_REGION_RANGE_TYPE) {
+ admin_range.address = range.address + SMALL_METADATA_START;
+ admin_range.size = SMALL_METADATA_SIZE;
+ recorder(task, context, MALLOC_ADMIN_REGION_RANGE_TYPE, &admin_range, 1);
+ }
+ if (type_mask & (MALLOC_PTR_REGION_RANGE_TYPE | MALLOC_ADMIN_REGION_RANGE_TYPE)) {
+ ptr_range.address = range.address;
+ ptr_range.size = NUM_SMALL_BLOCKS * SMALL_QUANTUM;
+ recorder(task, context, MALLOC_PTR_REGION_RANGE_TYPE, &ptr_range, 1);
+ }
+ if (type_mask & MALLOC_PTR_IN_USE_RANGE_TYPE) {
+ err = reader(task, range.address, range.size, (void **)&mapped_region);
+ if (err) {
+ return err;
+ }
+
+ mag_index_t mag_index = MAGAZINE_INDEX_FOR_SMALL_REGION(mapped_region);
+ magazine_t *small_mag_ptr = small_mag_base + mag_index;
+
+ int cached_free_blocks = 0;
+#if CONFIG_SMALL_CACHE
+ // Each magazine could have a pointer to a cached free block from
+ // this region. Count the regions that have such a pointer.
+ for (mag_index = 0; mag_index < szone->small_rack.num_magazines; mag_index++) {
+ if ((void *)range.address == (small_mag_base + mag_index)->mag_last_free_rgn) {
+ cached_free_blocks++;
+ }
+ }
+#endif // CONFIG_SMALL_CACHE
+
+ block_header = (msize_t *)(mapped_region + SMALL_METADATA_START + sizeof(region_trailer_t));
+ block_index = 0;
+ block_limit = NUM_SMALL_BLOCKS;
+ if (region == small_mag_ptr->mag_last_region) {
+ block_index += SMALL_MSIZE_FOR_BYTES(small_mag_ptr->mag_bytes_free_at_start);
+ block_limit -= SMALL_MSIZE_FOR_BYTES(small_mag_ptr->mag_bytes_free_at_end);
+ }
+
+ for (;block_index < block_limit; block_index += msize) {
+ msize_and_free = block_header[block_index];
+ msize = msize_and_free & ~SMALL_IS_FREE;
+ if (!msize) {
+ return KERN_FAILURE; // Somethings amiss. Avoid looping at this block_index.
+ }
+ if (!(msize_and_free & SMALL_IS_FREE)) {
+ vm_address_t ptr = range.address + SMALL_BYTES_FOR_MSIZE(block_index);
+#if CONFIG_SMALL_CACHE
+ // If there are still magazines that have cached free
+ // blocks in this region, check whether this is one of
+ // them and don't return the block pointer if it is.
+ boolean_t block_cached = false;
+ if (cached_free_blocks) {
+ for (mag_index = 0; mag_index < szone->small_rack.num_magazines; mag_index++) {
+ if ((void *)ptr == (small_mag_base + mag_index)->mag_last_free) {
+ block_cached = true;
+ cached_free_blocks--;
+ break;
+ }
+ }
+ }
+ if (block_cached) {
+ continue;
+ }
+#endif // CONFIG_SMALL_CACHE
+ // Block in use
+ buffer[count].address = ptr;
+ buffer[count].size = SMALL_BYTES_FOR_MSIZE(msize);
+ count++;
+ if (count >= MAX_RECORDER_BUFFER) {
+ recorder(task, context, MALLOC_PTR_IN_USE_RANGE_TYPE, buffer, count);
+ count = 0;
+ }
+ }
+ }
+ if (count) {
+ recorder(task, context, MALLOC_PTR_IN_USE_RANGE_TYPE, buffer, count);
+ count = 0;
+ }
+ }
+ }
+ }
+ return 0;
+}
+
+static void *
+small_malloc_from_free_list(rack_t *rack, magazine_t *small_mag_ptr, mag_index_t mag_index, msize_t msize)
+{
+ msize_t this_msize;
+ grain_t slot = SMALL_FREE_SLOT_FOR_MSIZE(rack, msize);
+ free_list_t *free_list = small_mag_ptr->mag_free_list;
+ free_list_t *the_slot = free_list + slot;
+ free_list_t *limit;
+ unsigned bitmap;
+ msize_t leftover_msize;
+ void *leftover_ptr;
+ void *ptr;
+
+ // Assumes we've locked the region
+ CHECK_MAGAZINE_PTR_LOCKED(szone, small_mag_ptr, __PRETTY_FUNCTION__);
+
+ // Look for an exact match by checking the freelist for this msize.
+ if (small_free_list_get_ptr(*the_slot)) {
+ ptr = small_free_list_get_ptr(*the_slot);
+ this_msize = msize;
+ small_free_list_remove_ptr(rack, small_mag_ptr, *the_slot, msize);
+ goto return_small_alloc;
+ }
+
+ // Mask off the bits representing slots holding free blocks smaller than
+ // the size we need. If there are no larger free blocks, try allocating
+ // from the free space at the end of the small region.
+ //
+ // BITMAPN_CTZ implementation
+ unsigned idx = slot >> 5;
+ bitmap = 0;
+ unsigned mask = ~((1 << (slot & 31)) - 1);
+ for (; idx < SMALL_FREELIST_BITMAP_WORDS(rack); ++idx) {
+ bitmap = small_mag_ptr->mag_bitmap[idx] & mask;
+ if (bitmap != 0) {
+ break;
+ }
+ mask = ~0U;
+ }
+ // Check for fallthrough: No bits set in bitmap
+ if ((bitmap == 0) && (idx == SMALL_FREELIST_BITMAP_WORDS(rack))) {
+ goto try_small_from_end;
+ }
+
+ // Start looking at the first set bit, plus 32 bits for every word of
+ // zeroes or entries that were too small.
+ slot = BITMAP32_CTZ((&bitmap)) + (idx * 32);
+
+ // FIXME: Explain use of - 1 here, last slot has special meaning
+ limit = free_list + SMALL_FREE_SLOT_COUNT(rack) - 1;
+ free_list += slot;
+
+ // Attempt to pull off the free_list slot that we now think is full.
+ if ((ptr = small_free_list_get_ptr(*free_list))) {
+ this_msize = SMALL_PTR_SIZE(ptr);
+ small_free_list_remove_ptr(rack, small_mag_ptr, *free_list, this_msize);
+ goto add_leftover_and_proceed;
+ }
+
+#if DEBUG_MALLOC
+ malloc_report(ASL_LEVEL_ERR, "in small_malloc_from_free_list(), mag_bitmap out of sync, slot=%d\n", slot);
+#endif
+
+try_small_from_end:
+ // Let's see if we can use small_mag_ptr->mag_bytes_free_at_end
+ if (small_mag_ptr->mag_bytes_free_at_end >= SMALL_BYTES_FOR_MSIZE(msize)) {
+ ptr = SMALL_REGION_END(small_mag_ptr->mag_last_region) - small_mag_ptr->mag_bytes_free_at_end;
+ small_mag_ptr->mag_bytes_free_at_end -= SMALL_BYTES_FOR_MSIZE(msize);
+ if (small_mag_ptr->mag_bytes_free_at_end) {
+ // let's mark this block as in use to serve as boundary
+ small_meta_header_set_in_use(SMALL_META_HEADER_FOR_PTR(ptr),
+ SMALL_META_INDEX_FOR_PTR((unsigned char *)ptr + SMALL_BYTES_FOR_MSIZE(msize)),
+ SMALL_MSIZE_FOR_BYTES(small_mag_ptr->mag_bytes_free_at_end));
+ }
+ this_msize = msize;
+ goto return_small_alloc;
+ }
+#if CONFIG_ASLR_INTERNAL
+ // Try from start if nothing left at end
+ if (small_mag_ptr->mag_bytes_free_at_start >= SMALL_BYTES_FOR_MSIZE(msize)) {
+ ptr = SMALL_REGION_ADDRESS(small_mag_ptr->mag_last_region) + small_mag_ptr->mag_bytes_free_at_start -
+ SMALL_BYTES_FOR_MSIZE(msize);
+ small_mag_ptr->mag_bytes_free_at_start -= SMALL_BYTES_FOR_MSIZE(msize);
+ if (small_mag_ptr->mag_bytes_free_at_start) {
+ // let's mark this block as in use to serve as boundary
+ small_meta_header_set_in_use(
+ SMALL_META_HEADER_FOR_PTR(ptr), 0, SMALL_MSIZE_FOR_BYTES(small_mag_ptr->mag_bytes_free_at_start));
+ }
+ this_msize = msize;
+ goto return_small_alloc;
+ }
+#endif
+ return NULL;
+
+add_leftover_and_proceed:
+ if (this_msize > msize) {
+ leftover_msize = this_msize - msize;
+ leftover_ptr = (unsigned char *)ptr + SMALL_BYTES_FOR_MSIZE(msize);
+#if DEBUG_MALLOC
+ if (LOG(szone, ptr)) {
+ malloc_report(ASL_LEVEL_INFO, "in small_malloc_from_free_list(), adding leftover ptr=%p, this_msize=%d\n", ptr, this_msize);
+ }
+#endif
+ small_free_list_add_ptr(rack, small_mag_ptr, leftover_ptr, leftover_msize);
+ this_msize = msize;
+ }
+
+return_small_alloc:
+ small_mag_ptr->mag_num_objects++;
+ small_mag_ptr->mag_num_bytes_in_objects += SMALL_BYTES_FOR_MSIZE(this_msize);
+
+ // Check that the region cookie is intact and update the region's bytes in use count
+ region_t *region = SMALL_REGION_FOR_PTR(ptr);
+ region_trailer_t *trailer = REGION_TRAILER_FOR_SMALL_REGION(region);
+ region_check_cookie(region, trailer);
+ size_t bytes_used = trailer->bytes_used + SMALL_BYTES_FOR_MSIZE(this_msize);
+ trailer->bytes_used = (unsigned int)bytes_used;
+
+ // Emptiness discriminant
+ if (bytes_used < DENSITY_THRESHOLD(SMALL_REGION_PAYLOAD_BYTES)) {
+ /* After this allocation the region is still sparse, so it must have been even more so before
+ * the allocation. That implies the region is already correctly marked. Do nothing. */
+ } else {
+ /* Region has crossed threshold from sparsity to density. Mark in not "suitable" on the
+ * recirculation candidates list. */
+ trailer->recirc_suitable = FALSE;
+ }
+#if DEBUG_MALLOC
+ if (LOG(szone, ptr)) {
+ malloc_report(ASL_LEVEL_INFO, "in small_malloc_from_free_list(), ptr=%p, this_msize=%d, msize=%d\n", ptr, this_msize, msize);
+ }
+#endif
+ small_meta_header_set_in_use(SMALL_META_HEADER_FOR_PTR(ptr), SMALL_META_INDEX_FOR_PTR(ptr), this_msize);
+ return ptr;
+}
+
+void *
+small_malloc_should_clear(rack_t *rack, msize_t msize, boolean_t cleared_requested)
+{
+ void *ptr;
+ mag_index_t mag_index = small_mag_get_thread_index() % rack->num_magazines;
+ magazine_t *small_mag_ptr = &(rack->magazines[mag_index]);
+
+ MALLOC_TRACE(TRACE_small_malloc, (uintptr_t)rack, SMALL_BYTES_FOR_MSIZE(msize), (uintptr_t)small_mag_ptr, cleared_requested);
+
+ SZONE_MAGAZINE_PTR_LOCK(small_mag_ptr);
+
+#if CONFIG_SMALL_CACHE
+ ptr = small_mag_ptr->mag_last_free;
+
+ if (small_mag_ptr->mag_last_free_msize == msize) {
+ // we have a winner
+ small_mag_ptr->mag_last_free = NULL;
+ small_mag_ptr->mag_last_free_msize = 0;
+ small_mag_ptr->mag_last_free_rgn = NULL;
+ SZONE_MAGAZINE_PTR_UNLOCK(small_mag_ptr);
+ CHECK(szone, __PRETTY_FUNCTION__);
+ if (cleared_requested) {
+ memset(ptr, 0, SMALL_BYTES_FOR_MSIZE(msize));
+ }
+ return ptr;
+ }
+#endif /* CONFIG_SMALL_CACHE */
+
+ while (1) {
+ ptr = small_malloc_from_free_list(rack, small_mag_ptr, mag_index, msize);
+ if (ptr) {
+ SZONE_MAGAZINE_PTR_UNLOCK(small_mag_ptr);
+ CHECK(szone, __PRETTY_FUNCTION__);
+ if (cleared_requested) {
+ memset(ptr, 0, SMALL_BYTES_FOR_MSIZE(msize));
+ }
+ return ptr;
+ }
+
+#if CONFIG_RECIRC_DEPOT
+ if (small_get_region_from_depot(rack, small_mag_ptr, mag_index, msize)) {
+ ptr = small_malloc_from_free_list(rack, small_mag_ptr, mag_index, msize);
+ if (ptr) {
+ SZONE_MAGAZINE_PTR_UNLOCK(small_mag_ptr);
+ CHECK(szone, __PRETTY_FUNCTION__);
+ if (cleared_requested) {
+ memset(ptr, 0, SMALL_BYTES_FOR_MSIZE(msize));
+ }
+ return ptr;
+ }
+ }
+#endif // CONFIG_RECIRC_DEPOT
+
+ // The magazine is exhausted. A new region (heap) must be allocated to satisfy this call to malloc().
+ // The allocation, an mmap() system call, will be performed outside the magazine spin locks by the first
+ // thread that suffers the exhaustion. That thread sets "alloc_underway" and enters a critical section.
+ // Threads arriving here later are excluded from the critical section, yield the CPU, and then retry the
+ // allocation. After some time the magazine is resupplied, the original thread leaves with its allocation,
+ // and retry-ing threads succeed in the code just above.
+ if (!small_mag_ptr->alloc_underway) {
+ void *fresh_region;
+
+ // time to create a new region (do this outside the magazine lock)
+ small_mag_ptr->alloc_underway = TRUE;
+ OSMemoryBarrier();
+ SZONE_MAGAZINE_PTR_UNLOCK(small_mag_ptr);
+ fresh_region = mvm_allocate_pages_securely(SMALL_REGION_SIZE, SMALL_BLOCKS_ALIGN, VM_MEMORY_MALLOC_SMALL, rack->debug_flags);
+ SZONE_MAGAZINE_PTR_LOCK(small_mag_ptr);
+
+ // DTrace USDT Probe
+ MAGMALLOC_ALLOCREGION(SMALL_SZONE_FROM_RACK(rack), (int)mag_index, fresh_region, SMALL_REGION_SIZE);
+
+ if (!fresh_region) { // out of memory!
+ small_mag_ptr->alloc_underway = FALSE;
+ OSMemoryBarrier();
+ SZONE_MAGAZINE_PTR_UNLOCK(small_mag_ptr);
+ return NULL;
+ }
+
+ region_set_cookie(REGION_TRAILER_FOR_SMALL_REGION(fresh_region));
+ ptr = small_malloc_from_region_no_lock(rack, small_mag_ptr, mag_index, msize, fresh_region);
+
+ // we don't clear because this freshly allocated space is pristine
+ small_mag_ptr->alloc_underway = FALSE;
+ OSMemoryBarrier();
+ SZONE_MAGAZINE_PTR_UNLOCK(small_mag_ptr);
+ CHECK(szone, __PRETTY_FUNCTION__);
+ return ptr;
+ } else {
+ SZONE_MAGAZINE_PTR_UNLOCK(small_mag_ptr);
+ yield();
+ SZONE_MAGAZINE_PTR_LOCK(small_mag_ptr);
+ }
+ }
+ /* NOTREACHED */
+}
+
+size_t
+small_size(rack_t *rack, const void *ptr)
+{
+ if (small_region_for_ptr_no_lock(rack, ptr)) {
+ if (SMALL_META_INDEX_FOR_PTR(ptr) >= NUM_SMALL_BLOCKS) {
+ return 0;
+ }
+ msize_t msize_and_free = *SMALL_METADATA_FOR_PTR(ptr);
+ if (msize_and_free & SMALL_IS_FREE) {
+ return 0;
+ }
+#if CONFIG_SMALL_CACHE
+ {
+ mag_index_t mag_index = MAGAZINE_INDEX_FOR_SMALL_REGION(SMALL_REGION_FOR_PTR(ptr));
+ if (DEPOT_MAGAZINE_INDEX != mag_index) {
+ magazine_t *small_mag_ptr = &(rack->magazines[mag_index]);
+
+ if (ptr == small_mag_ptr->mag_last_free) {
+ return 0;
+ }
+ } else {
+ for (mag_index = 0; mag_index < rack->num_magazines; mag_index++) {
+ magazine_t *small_mag_ptr = &(rack->magazines[mag_index]);
+
+ if (ptr == small_mag_ptr->mag_last_free) {
+ return 0;
+ }
+ }
+ }
+ }
+#endif
+ return SMALL_BYTES_FOR_MSIZE(msize_and_free);
+ }
+
+ return 0;
+}
+
+static MALLOC_NOINLINE void
+free_small_botch(rack_t *rack, void *ptr)
+{
+ mag_index_t mag_index = MAGAZINE_INDEX_FOR_SMALL_REGION(SMALL_REGION_FOR_PTR(ptr));
+ magazine_t *small_mag_ptr = &(rack->magazines[mag_index]);
+ SZONE_MAGAZINE_PTR_UNLOCK(small_mag_ptr);
+ malloc_zone_error(rack->debug_flags, true, "double free for ptr %p\n", ptr);
+}
+
+void
+free_small(rack_t *rack, void *ptr, region_t small_region, size_t known_size)
+{
+ msize_t msize;
+ mag_index_t mag_index = MAGAZINE_INDEX_FOR_SMALL_REGION(SMALL_REGION_FOR_PTR(ptr));
+ magazine_t *small_mag_ptr = &(rack->magazines[mag_index]);
+
+ // ptr is known to be in small_region
+ if (known_size) {
+ msize = SMALL_MSIZE_FOR_BYTES(known_size + SMALL_QUANTUM - 1);
+ } else {
+ msize = SMALL_PTR_SIZE(ptr);
+ if (SMALL_PTR_IS_FREE(ptr)) {
+ free_small_botch(rack, ptr);
+ return;
+ }
+ }
+
+ SZONE_MAGAZINE_PTR_LOCK(small_mag_ptr);
+
+#if CONFIG_SMALL_CACHE
+ // Depot does not participate in CONFIG_SMALL_CACHE since it can't be directly malloc()'d
+ if (DEPOT_MAGAZINE_INDEX != mag_index) {
+ void *ptr2 = small_mag_ptr->mag_last_free; // Might be NULL
+ msize_t msize2 = small_mag_ptr->mag_last_free_msize;
+ region_t rgn2 = small_mag_ptr->mag_last_free_rgn;
+
+ /* check that we don't already have this pointer in the cache */
+ if (ptr == ptr2) {
+ free_small_botch(rack, ptr);
+ return;
+ }
+
+ if ((rack->debug_flags & MALLOC_DO_SCRIBBLE) && msize) {
+ memset(ptr, SCRABBLE_BYTE, SMALL_BYTES_FOR_MSIZE(msize));
+ }
+
+ small_mag_ptr->mag_last_free = ptr;
+ small_mag_ptr->mag_last_free_msize = msize;
+ small_mag_ptr->mag_last_free_rgn = small_region;
+
+ if (!ptr2) {
+ SZONE_MAGAZINE_PTR_UNLOCK(small_mag_ptr);
+ CHECK(szone, __PRETTY_FUNCTION__);
+ return;
+ }
+
+ msize = msize2;
+ ptr = ptr2;
+ small_region = rgn2;
+ }
+#endif /* CONFIG_SMALL_CACHE */
+
+ // Now in the time it took to acquire the lock, the region may have migrated
+ // from one magazine to another. I.e. trailer->mag_index is volatile.
+ // In which case the magazine lock we obtained (namely magazines[mag_index].mag_lock)
+ // is stale. If so, keep on tryin' ...
+ region_trailer_t *trailer = REGION_TRAILER_FOR_SMALL_REGION(small_region);
+ mag_index_t refreshed_index;
+
+ while (mag_index != (refreshed_index = trailer->mag_index)) { // Note assignment
+
+ SZONE_MAGAZINE_PTR_UNLOCK(small_mag_ptr);
+
+ mag_index = refreshed_index;
+ small_mag_ptr = &(rack->magazines[mag_index]);
+ SZONE_MAGAZINE_PTR_LOCK(small_mag_ptr);
+ }
+
+ if (small_free_no_lock(rack, small_mag_ptr, mag_index, small_region, ptr, msize)) {
+ SZONE_MAGAZINE_PTR_UNLOCK(small_mag_ptr);
+ }
+
+ CHECK(szone, __PRETTY_FUNCTION__);
+}
+
+void
+print_small_free_list(task_t task, memory_reader_t reader,
+ print_task_printer_t printer, rack_t *rack)
+{
+ free_list_t ptr;
+ _SIMPLE_STRING b = _simple_salloc();
+ mag_index_t mag_index;
+
+ if (b) {
+ rack_t *mapped_rack;
+ magazine_t *mapped_magazines;
+ if (reader(task, (vm_address_t)rack, sizeof(struct rack_s),
+ (void **)&mapped_rack)) {
+ printer("Failed to map small rack\n");
+ return;
+ }
+ if (reader(task, (vm_address_t)mapped_rack->magazines,
+ mapped_rack->num_magazines * sizeof(magazine_t),
+ (void **)&mapped_magazines)) {
+ printer("Failed to map small rack magazines\n");
+ return;
+ }
+
+ _simple_sappend(b, "small free sizes:\n");
+ grain_t free_slots = SMALL_FREE_SLOT_COUNT(mapped_rack);
+ for (mag_index = -1; mag_index < mapped_rack->num_magazines;
+ mag_index++) {
+ grain_t slot = 0;
+ if (mag_index == -1) {
+ _simple_sprintf(b, "\tRecirc depot: ");
+ } else {
+ _simple_sprintf(b, "\tMagazine %d: ", mag_index);
+ }
+ while (slot < free_slots) {
+ ptr = mapped_magazines[mag_index].mag_free_list[slot];
+ if (small_free_list_get_ptr_task(task, reader, printer, ptr)) {
+ _simple_sprintf(b, "%s%y[%d]; ", (slot == free_slots - 1) ?
+ ">=" : "", (slot + 1) * SMALL_QUANTUM,
+ small_free_list_count(task, reader, printer,
+ rack, ptr));
+ }
+ slot++;
+ }
+ _simple_sappend(b, "\n");
+ }
+ printer("%s\n", _simple_string(b));
+ _simple_sfree(b);
+ }
+}
+
+void
+print_small_region(task_t task, memory_reader_t reader,
+ print_task_printer_t printer, szone_t *szone, int level,
+ region_t region, size_t bytes_at_start, size_t bytes_at_end)
+{
+ unsigned counts[1024];
+ unsigned in_use = 0;
+ uintptr_t start = (uintptr_t)SMALL_REGION_ADDRESS(region);
+ uintptr_t current = start + bytes_at_start;
+ uintptr_t limit = (uintptr_t)SMALL_REGION_END(region) - bytes_at_end;
+ uintptr_t mapped_start;
+ msize_t msize_and_free;
+ msize_t msize;
+ unsigned ci;
+ _SIMPLE_STRING b;
+ uintptr_t pgTot = 0;
+
+ if (reader(task, (vm_address_t)start, SMALL_REGION_SIZE,
+ (void **)&mapped_start)) {
+ printer("Failed to map small region at %p\n", start);
+ return;
+ }
+ off_t start_offset = mapped_start - start;
+ region_t mapped_region = (region_t)mapped_start;
+
+ if (region == HASHRING_REGION_DEALLOCATED) {
+ if ((b = _simple_salloc()) != NULL) {
+ _simple_sprintf(b, "Small region [unknown address] was returned to the OS\n");
+ printer("%s\n", _simple_string(b));
+ _simple_sfree(b);
+ }
+ return;
+ }
+
+ memset(counts, 0, sizeof(counts));
+ while (current < limit) {
+ msize_and_free = *(uintptr_t *)((char *)SMALL_METADATA_FOR_PTR(current) + start_offset);
+ msize = msize_and_free & ~SMALL_IS_FREE;
+ if (!msize) {
+ printer("*** error with %p: msize=%d, free: %x\n", (void *)current,
+ (unsigned)msize, msize_and_free & SMALL_IS_FREE);
+ break;
+ }
+ if (!(msize_and_free & SMALL_IS_FREE)) {
+ // block in use
+ if (msize < 1024) {
+ counts[msize]++;
+ }
+ in_use++;
+ } else {
+ uintptr_t pgLo = round_page_quanta(current +
+ sizeof(free_list_t) + sizeof(msize_t));
+ uintptr_t pgHi = trunc_page_quanta(current +
+ SMALL_BYTES_FOR_MSIZE(msize) - sizeof(msize_t));
+
+ if (pgLo < pgHi) {
+ pgTot += (pgHi - pgLo);
+ }
+ }
+ current += SMALL_BYTES_FOR_MSIZE(msize);
+ }
+
+ if ((b = _simple_salloc()) != NULL) {
+ mag_index_t mag_index = MAGAZINE_INDEX_FOR_SMALL_REGION(mapped_region);
+ _simple_sprintf(b, "Small region [%p-%p, %y] \t", (void *)start,
+ SMALL_REGION_END(region), (int)SMALL_REGION_SIZE);
+ if (mag_index == DEPOT_MAGAZINE_INDEX) {
+ _simple_sprintf(b, "Recirc depot \t");
+ } else {
+ _simple_sprintf(b, "Magazine=%d \t", mag_index);
+ }
+ _simple_sprintf(b, "Allocations in use=%d \t Bytes in use=%ly (%d%%) \t",
+ in_use, BYTES_USED_FOR_SMALL_REGION(mapped_region),
+ (int)(100.0F * BYTES_USED_FOR_SMALL_REGION(mapped_region))/SMALL_REGION_SIZE);
+ if (bytes_at_end || bytes_at_start) {
+ _simple_sprintf(b, "Untouched=%ly ", bytes_at_end + bytes_at_start);
+ }
+ if (mag_index == DEPOT_MAGAZINE_INDEX) {
+ _simple_sprintf(b, "Advised MADV_FREE=%ly", pgTot);
+ } else {
+ _simple_sprintf(b, "Fragments subject to reclamation=%ly", pgTot);
+#if CONFIG_RECIRC_DEPOT
+ _simple_sprintf(b, small_region_below_recirc_threshold(mapped_region) ?
+ "\tEmpty enough to be moved to recirc depot" :
+ "\tNot empty enough to be moved to recirc depot");
+#endif // CONFIG_RECIRC_DEPOT
+ }
+ if (level >= MALLOC_VERBOSE_PRINT_LEVEL && in_use) {
+ _simple_sappend(b, "\n\tSizes in use: ");
+ for (ci = 0; ci < 1024; ci++) {
+ if (counts[ci]) {
+ _simple_sprintf(b, "%y[%d] ", SMALL_BYTES_FOR_MSIZE(ci),
+ counts[ci]);
+ }
+ }
+ }
+ printer("%s\n", _simple_string(b));
+ _simple_sfree(b);
+ }
+}
+
+static char *small_freelist_fail_msg = "check: small free list incorrect";
+
+#define SMALL_FREELIST_FAIL(fmt, ...) \
+ malloc_zone_check_fail(small_freelist_fail_msg, \
+ " (slot=%u), counter=%d\n" fmt, slot, counter, __VA_ARGS__);
+
+boolean_t
+small_free_list_check(rack_t *rack, grain_t slot, unsigned counter)
+{
+ mag_index_t mag_index;
+
+ for (mag_index = -1; mag_index < rack->num_magazines; mag_index++) {
+ magazine_t *small_mag_ptr = &(rack->magazines[mag_index]);
+ SZONE_MAGAZINE_PTR_LOCK(small_mag_ptr);
+
+ unsigned count = 0;
+ free_list_t current = rack->magazines[mag_index].mag_free_list[slot];
+ free_list_t previous = (free_list_t){ .p = NULL };
+ msize_t msize_and_free;
+ void *ptr = NULL;
+
+ while ((ptr = small_free_list_get_ptr(current))) {
+ msize_and_free = *SMALL_METADATA_FOR_PTR(ptr);
+ if (!(msize_and_free & SMALL_IS_FREE)) {
+ SMALL_FREELIST_FAIL("*** in-use ptr in free list slot=%u count=%d ptr=%p\n", slot, count, ptr);
+ SZONE_MAGAZINE_PTR_UNLOCK(small_mag_ptr);
+ return 0;
+ }
+ if (((uintptr_t)ptr) & (SMALL_QUANTUM - 1)) {
+ SMALL_FREELIST_FAIL("*** unaligned ptr in free list slot=%u count=%d ptr=%p\n", slot, count, ptr);
+ SZONE_MAGAZINE_PTR_UNLOCK(small_mag_ptr);
+ return 0;
+ }
+ if (!small_region_for_ptr_no_lock(rack, ptr)) {
+ SMALL_FREELIST_FAIL("*** ptr not in szone slot=%d count=%d ptr=%p\n", slot, count, ptr);
+ SZONE_MAGAZINE_PTR_UNLOCK(small_mag_ptr);
+ return 0;
+ }
+ if (small_free_list_get_previous(rack, current).p != previous.p) {
+ SMALL_FREELIST_FAIL("*** previous incorrectly set slot=%u count=%d ptr=%p\n", slot, count, ptr);
+ SZONE_MAGAZINE_PTR_UNLOCK(small_mag_ptr);
+ return 0;
+ }
+ previous = current;
+ current = small_free_list_get_next(rack, current);
+ count++;
+ }
+
+ SZONE_MAGAZINE_PTR_UNLOCK(small_mag_ptr);
+ }
+ return 1;
+}