--- /dev/null
+/*
+ * Copyright (c) 2012 Apple Inc. All rights reserved.
+ *
+ * @APPLE_OSREFERENCE_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. The rights granted to you under the License
+ * may not be used to create, or enable the creation or redistribution of,
+ * unlawful or unlicensed copies of an Apple operating system, or to
+ * circumvent, violate, or enable the circumvention or violation of, any
+ * terms of an Apple operating system software license agreement.
+ *
+ * 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_OSREFERENCE_LICENSE_HEADER_END@
+ */
+
+#include <stddef.h>
+#include <kern/btlog.h>
+#include <kern/assert.h>
+#include <vm/vm_kern.h>
+#include <vm/vm_map.h>
+#include <mach/vm_param.h>
+
+/*
+ * Since all records are located contiguously in memory,
+ * we use indices to them as the primary lookup mechanism,
+ * and to maintain the linked list of active records
+ * in chronological order.
+ */
+typedef uint32_t btlog_recordindex_t; /* only 24 bits used */
+#define BTLOG_RECORDINDEX_NONE (0xFFFFFF)
+#define BTLOG_MAX_RECORDS (0xFFFFFF /* 16777215 */)
+
+typedef struct btlog_record {
+ btlog_recordindex_t next:24;
+ uint8_t operation;
+#if __LP64__
+ uint32_t _pad;
+#endif
+ void *element;
+ void *bt[]; /* variable sized, based on btlog_t params */
+} btlog_record_t;
+
+struct btlog {
+ vm_address_t btlog_buffer; /* all memory for this btlog_t */
+ vm_size_t btlog_buffersize;
+
+ btlog_lock_t lock_callback; /* caller-provided locking */
+ btlog_unlock_t unlock_callback;
+ void *callback_context;
+
+ uintptr_t btrecords; /* use btlog_recordindex_t to lookup */
+ size_t btrecord_count;
+ size_t btrecord_btdepth; /* BT entries per record */
+ size_t btrecord_size;
+
+ btlog_recordindex_t head; /* active record list */
+ btlog_recordindex_t tail;
+ size_t activecount;
+
+ btlog_recordindex_t freelist;
+};
+
+extern boolean_t kmem_alloc_ready;
+
+#define lookup_btrecord(btlog, index) \
+ ((btlog_record_t *)(btlog->btrecords + index * btlog->btrecord_size))
+
+btlog_t *
+btlog_create(size_t numrecords,
+ size_t record_btdepth,
+ btlog_lock_t lock_callback,
+ btlog_unlock_t unlock_callback,
+ void *callback_context)
+{
+ btlog_t *btlog;
+ vm_size_t buffersize_needed;
+ vm_address_t buffer = 0;
+ size_t i;
+ kern_return_t ret;
+ size_t btrecord_size;
+
+ if (!kmem_alloc_ready)
+ return NULL;
+
+ if (numrecords > BTLOG_MAX_RECORDS)
+ return NULL;
+
+ if (numrecords == 0)
+ return NULL;
+
+ if (record_btdepth > BTLOG_MAX_DEPTH)
+ return NULL;
+
+ if ((lock_callback && !unlock_callback) ||
+ (!lock_callback && unlock_callback))
+ return NULL;
+
+ /* btlog_record_t is variable-sized, calculate needs now */
+ btrecord_size = sizeof(btlog_record_t)
+ + sizeof(void *) * record_btdepth;
+
+ buffersize_needed = sizeof(btlog_t) + numrecords * btrecord_size;
+ buffersize_needed = round_page(buffersize_needed);
+
+ /* since rounding to a page size might hold more, recalculate */
+ numrecords = MIN(BTLOG_MAX_RECORDS,
+ (buffersize_needed - sizeof(btlog_t))/btrecord_size);
+
+ ret = kmem_alloc(kernel_map, &buffer, buffersize_needed);
+ if (ret != KERN_SUCCESS)
+ return NULL;
+
+ btlog = (btlog_t *)buffer;
+ btlog->btlog_buffer = buffer;
+ btlog->btlog_buffersize = buffersize_needed;
+
+ btlog->lock_callback = lock_callback;
+ btlog->unlock_callback = unlock_callback;
+ btlog->callback_context = callback_context;
+
+ btlog->btrecords = (uintptr_t)(buffer + sizeof(btlog_t));
+ btlog->btrecord_count = numrecords;
+ btlog->btrecord_btdepth = record_btdepth;
+ btlog->btrecord_size = btrecord_size;
+
+ btlog->head = BTLOG_RECORDINDEX_NONE;
+ btlog->tail = BTLOG_RECORDINDEX_NONE;
+ btlog->activecount = 0;
+
+ /* populate freelist with all records in order */
+ btlog->freelist = 0;
+ for (i=0; i < (numrecords - 1); i++) {
+ btlog_record_t *rec = lookup_btrecord(btlog, i);
+ rec->next = (btlog_recordindex_t)(i + 1);
+ }
+ lookup_btrecord(btlog, i)->next = BTLOG_RECORDINDEX_NONE; /* terminate */
+
+ return btlog;
+}
+
+/* Assumes btlog is already locked */
+static btlog_recordindex_t
+btlog_get_record_from_freelist(btlog_t *btlog)
+{
+ btlog_recordindex_t recindex = btlog->freelist;
+
+ if (recindex == BTLOG_RECORDINDEX_NONE) {
+ /* nothing on freelist */
+ return BTLOG_RECORDINDEX_NONE;
+ } else {
+ /* remove the head of the freelist */
+ btlog_record_t *record = lookup_btrecord(btlog, recindex);
+ btlog->freelist = record->next;
+ return recindex;
+ }
+}
+
+/* Assumes btlog is already locked */
+static btlog_recordindex_t
+btlog_evict_record_from_activelist(btlog_t *btlog)
+{
+ btlog_recordindex_t recindex = btlog->head;
+
+ if (recindex == BTLOG_RECORDINDEX_NONE) {
+ /* nothing on active list */
+ return BTLOG_RECORDINDEX_NONE;
+ } else {
+ /* remove the head of the active list */
+ btlog_record_t *record = lookup_btrecord(btlog, recindex);
+ btlog->head = record->next;
+ btlog->activecount--;
+ if (btlog->head == BTLOG_RECORDINDEX_NONE) {
+ /* active list is now empty, update tail */
+ btlog->tail = BTLOG_RECORDINDEX_NONE;
+ }
+ return recindex;
+ }
+}
+
+/* Assumes btlog is already locked */
+static void
+btlog_append_record_to_activelist(btlog_t *btlog, btlog_recordindex_t recindex)
+{
+ if (btlog->head == BTLOG_RECORDINDEX_NONE) {
+ /* empty active list, update both head and tail */
+ btlog->head = btlog->tail = recindex;
+ } else {
+ btlog_record_t *record = lookup_btrecord(btlog, btlog->tail);
+ record->next = recindex;
+ btlog->tail = recindex;
+ }
+ btlog->activecount++;
+}
+
+void
+btlog_add_entry(btlog_t *btlog,
+ void *element,
+ uint8_t operation,
+ void *bt[],
+ size_t btcount)
+{
+ btlog_recordindex_t recindex;
+ btlog_record_t *record;
+ size_t i;
+
+ if (btlog->lock_callback)
+ btlog->lock_callback(btlog->callback_context);
+
+ /* If there's a free record, use it */
+ recindex = btlog_get_record_from_freelist(btlog);
+ if (recindex == BTLOG_RECORDINDEX_NONE) {
+ /* Use the first active record (FIFO age-out) */
+ recindex = btlog_evict_record_from_activelist(btlog);
+ assert(recindex != BTLOG_RECORDINDEX_NONE);
+ }
+
+ record = lookup_btrecord(btlog, recindex);
+
+ /* we always add to the tail, so there is no next pointer */
+ record->next = BTLOG_RECORDINDEX_NONE;
+ record->operation = operation;
+ record->element = element;
+ for (i=0; i < MIN(btcount, btlog->btrecord_btdepth); i++) {
+ record->bt[i] = bt[i];
+ }
+ for (; i < btlog->btrecord_btdepth; i++) {
+ record->bt[i] = NULL;
+ }
+
+ btlog_append_record_to_activelist(btlog, recindex);
+
+ if (btlog->unlock_callback)
+ btlog->unlock_callback(btlog->callback_context);
+}
+
+void
+btlog_remove_entries_for_element(btlog_t *btlog,
+ void *element)
+{
+ btlog_recordindex_t recindex;
+ btlog_record_t *record;
+
+ if (btlog->lock_callback)
+ btlog->lock_callback(btlog->callback_context);
+
+ /*
+ * Since the btlog_t anchors the active
+ * list with a pointer to the head of
+ * the list, first loop making sure
+ * the head is correct (and doesn't
+ * match the element being removed).
+ */
+ recindex = btlog->head;
+ record = lookup_btrecord(btlog, recindex);
+ while (recindex != BTLOG_RECORDINDEX_NONE) {
+ if (record->element == element) {
+ /* remove head of active list */
+ btlog->head = record->next;
+ btlog->activecount--;
+
+ /* add to freelist */
+ record->next = btlog->freelist;
+ btlog->freelist = recindex;
+
+ /* check the new head */
+ recindex = btlog->head;
+ record = lookup_btrecord(btlog, recindex);
+ } else {
+ /* head didn't match, so we can move on */
+ break;
+ }
+ }
+
+ if (recindex == BTLOG_RECORDINDEX_NONE) {
+ /* we iterated over the entire active list removing the element */
+ btlog->tail = BTLOG_RECORDINDEX_NONE;
+ } else {
+ /* the head of the active list is stable, now remove other entries */
+ btlog_recordindex_t precindex = recindex;
+ btlog_record_t *precord = record;
+
+ recindex = precord->next;
+ record = lookup_btrecord(btlog, recindex);
+ while (recindex != BTLOG_RECORDINDEX_NONE) {
+ if (record->element == element) {
+ /* remove in place */
+ precord->next = record->next;
+ btlog->activecount--;
+
+ /* add to freelist */
+ record->next = btlog->freelist;
+ btlog->freelist = recindex;
+
+ /* check the next record */
+ recindex = precord->next;
+ record = lookup_btrecord(btlog, recindex);
+ } else {
+ /* check the next record */
+ precindex = recindex;
+ precord = record;
+
+ recindex = record->next;
+ record = lookup_btrecord(btlog, recindex);
+ }
+ }
+
+ /* We got to the end of the active list. Update the tail */
+ btlog->tail = precindex;
+ }
+
+ if (btlog->unlock_callback)
+ btlog->unlock_callback(btlog->callback_context);
+
+}
projects / apple / xnu.git / blobdiff