[apple/xnu.git] / osfmk / kern / btlog.c

/*
 * 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);

}
Commit	Line	Data
39236c6e A	1	/*
	2	* Copyright (c) 2012 Apple Inc. All rights reserved.
	3	*
	4	* @APPLE_OSREFERENCE_LICENSE_HEADER_START@
	5	*
	6	* This file contains Original Code and/or Modifications of Original Code
	7	* as defined in and that are subject to the Apple Public Source License
	8	* Version 2.0 (the 'License'). You may not use this file except in
	9	* compliance with the License. The rights granted to you under the License
	10	* may not be used to create, or enable the creation or redistribution of,
	11	* unlawful or unlicensed copies of an Apple operating system, or to
	12	* circumvent, violate, or enable the circumvention or violation of, any
	13	* terms of an Apple operating system software license agreement.
	14	*
	15	* Please obtain a copy of the License at
	16	* http://www.opensource.apple.com/apsl/ and read it before using this file.
	17	*
	18	* The Original Code and all software distributed under the License are
	19	* distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
	20	* EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
	21	* INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
	22	* FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
	23	* Please see the License for the specific language governing rights and
	24	* limitations under the License.
	25	*
	26	* @APPLE_OSREFERENCE_LICENSE_HEADER_END@
	27	*/
	28
	29	#include <stddef.h>
	30	#include <kern/btlog.h>
	31	#include <kern/assert.h>
	32	#include <vm/vm_kern.h>
	33	#include <vm/vm_map.h>
	34	#include <mach/vm_param.h>
	35
	36	/*
	37	* Since all records are located contiguously in memory,
	38	* we use indices to them as the primary lookup mechanism,
	39	* and to maintain the linked list of active records
	40	* in chronological order.
	41	*/
	42	typedef uint32_t btlog_recordindex_t; /* only 24 bits used */
	43	#define BTLOG_RECORDINDEX_NONE (0xFFFFFF)
	44	#define BTLOG_MAX_RECORDS (0xFFFFFF /* 16777215 */)
	45
	46	typedef struct btlog_record {
	47	btlog_recordindex_t next:24;
	48	uint8_t operation;
	49	#if __LP64__
	50	uint32_t _pad;
	51	#endif
	52	void *element;
	53	void bt[]; / variable sized, based on btlog_t params */
	54	} btlog_record_t;
	55
	56	struct btlog {
	57	vm_address_t btlog_buffer; /* all memory for this btlog_t */
	58	vm_size_t btlog_buffersize;
	59
	60	btlog_lock_t lock_callback; /* caller-provided locking */
	61	btlog_unlock_t unlock_callback;
	62	void *callback_context;
	63
	64	uintptr_t btrecords; /* use btlog_recordindex_t to lookup */
65	size_t btrecord_count;
66	size_t btrecord_btdepth; /* BT entries per record */
67	size_t btrecord_size;
68
69	btlog_recordindex_t head; /* active record list */
70	btlog_recordindex_t tail;
71	size_t activecount;
72
73	btlog_recordindex_t freelist;
74	};
75
76	extern boolean_t kmem_alloc_ready;
77
78	#define lookup_btrecord(btlog, index) \
79	((btlog_record_t )(btlog->btrecords + index btlog->btrecord_size))
80
81	btlog_t *
82	btlog_create(size_t numrecords,
83	size_t record_btdepth,
84	btlog_lock_t lock_callback,
85	btlog_unlock_t unlock_callback,
86	void *callback_context)
87	{
88	btlog_t *btlog;
89	vm_size_t buffersize_needed;
90	vm_address_t buffer = 0;
91	size_t i;
92	kern_return_t ret;
93	size_t btrecord_size;
94
95	if (!kmem_alloc_ready)
96	return NULL;
97
98	if (numrecords > BTLOG_MAX_RECORDS)
99	return NULL;
100
101	if (numrecords == 0)
102	return NULL;
103
104	if (record_btdepth > BTLOG_MAX_DEPTH)
105	return NULL;
106
107	if ((lock_callback && !unlock_callback) \|\|
108	(!lock_callback && unlock_callback))
109	return NULL;
110
111	/* btlog_record_t is variable-sized, calculate needs now */
112	btrecord_size = sizeof(btlog_record_t)
113	+ sizeof(void ) record_btdepth;
114
115	buffersize_needed = sizeof(btlog_t) + numrecords * btrecord_size;
116	buffersize_needed = round_page(buffersize_needed);
117
118	/* since rounding to a page size might hold more, recalculate */
119	numrecords = MIN(BTLOG_MAX_RECORDS,
120	(buffersize_needed - sizeof(btlog_t))/btrecord_size);
121
122	ret = kmem_alloc(kernel_map, &buffer, buffersize_needed);
123	if (ret != KERN_SUCCESS)
124	return NULL;
125
126	btlog = (btlog_t *)buffer;
127	btlog->btlog_buffer = buffer;
128	btlog->btlog_buffersize = buffersize_needed;
129
130	btlog->lock_callback = lock_callback;
131	btlog->unlock_callback = unlock_callback;
132	btlog->callback_context = callback_context;
133
134	btlog->btrecords = (uintptr_t)(buffer + sizeof(btlog_t));
135	btlog->btrecord_count = numrecords;
136	btlog->btrecord_btdepth = record_btdepth;
137	btlog->btrecord_size = btrecord_size;
138
139	btlog->head = BTLOG_RECORDINDEX_NONE;
140	btlog->tail = BTLOG_RECORDINDEX_NONE;
141	btlog->activecount = 0;
142
143	/* populate freelist with all records in order */
144	btlog->freelist = 0;
145	for (i=0; i < (numrecords - 1); i++) {
146	btlog_record_t *rec = lookup_btrecord(btlog, i);
147	rec->next = (btlog_recordindex_t)(i + 1);
148	}
149	lookup_btrecord(btlog, i)->next = BTLOG_RECORDINDEX_NONE; /* terminate */
150
151	return btlog;
152	}
153
154	/* Assumes btlog is already locked */
155	static btlog_recordindex_t
156	btlog_get_record_from_freelist(btlog_t *btlog)
157	{
158	btlog_recordindex_t recindex = btlog->freelist;
159
160	if (recindex == BTLOG_RECORDINDEX_NONE) {
161	/* nothing on freelist */
162	return BTLOG_RECORDINDEX_NONE;
163	} else {
164	/* remove the head of the freelist */
165	btlog_record_t *record = lookup_btrecord(btlog, recindex);
166	btlog->freelist = record->next;
167	return recindex;
168	}
169	}
170
171	/* Assumes btlog is already locked */
172	static btlog_recordindex_t
173	btlog_evict_record_from_activelist(btlog_t *btlog)
174	{
175	btlog_recordindex_t recindex = btlog->head;
176
177	if (recindex == BTLOG_RECORDINDEX_NONE) {
178	/* nothing on active list */
179	return BTLOG_RECORDINDEX_NONE;
180	} else {
181	/* remove the head of the active list */
182	btlog_record_t *record = lookup_btrecord(btlog, recindex);
183	btlog->head = record->next;
184	btlog->activecount--;
185	if (btlog->head == BTLOG_RECORDINDEX_NONE) {
186	/* active list is now empty, update tail */
187	btlog->tail = BTLOG_RECORDINDEX_NONE;
188	}
189	return recindex;
190	}
191	}
192
193	/* Assumes btlog is already locked */
194	static void
195	btlog_append_record_to_activelist(btlog_t *btlog, btlog_recordindex_t recindex)
196	{
197	if (btlog->head == BTLOG_RECORDINDEX_NONE) {
198	/* empty active list, update both head and tail */
199	btlog->head = btlog->tail = recindex;
200	} else {
201	btlog_record_t *record = lookup_btrecord(btlog, btlog->tail);
202	record->next = recindex;
203	btlog->tail = recindex;
204	}
205	btlog->activecount++;
206	}
207
208	void
209	btlog_add_entry(btlog_t *btlog,
210	void *element,
211	uint8_t operation,
212	void *bt[],
213	size_t btcount)
214	{
215	btlog_recordindex_t recindex;
216	btlog_record_t *record;
217	size_t i;
218
219	if (btlog->lock_callback)
220	btlog->lock_callback(btlog->callback_context);
221
222	/* If there's a free record, use it */
223	recindex = btlog_get_record_from_freelist(btlog);
224	if (recindex == BTLOG_RECORDINDEX_NONE) {
225	/* Use the first active record (FIFO age-out) */
226	recindex = btlog_evict_record_from_activelist(btlog);
227	assert(recindex != BTLOG_RECORDINDEX_NONE);
228	}
229
230	record = lookup_btrecord(btlog, recindex);
231
232	/* we always add to the tail, so there is no next pointer */
233	record->next = BTLOG_RECORDINDEX_NONE;
234	record->operation = operation;
235	record->element = element;
236	for (i=0; i < MIN(btcount, btlog->btrecord_btdepth); i++) {
237	record->bt[i] = bt[i];
238	}
239	for (; i < btlog->btrecord_btdepth; i++) {
240	record->bt[i] = NULL;
241	}
242
243	btlog_append_record_to_activelist(btlog, recindex);
244
245	if (btlog->unlock_callback)
246	btlog->unlock_callback(btlog->callback_context);
247	}
248
249	void
250	btlog_remove_entries_for_element(btlog_t *btlog,
251	void *element)
252	{
253	btlog_recordindex_t recindex;
254	btlog_record_t *record;
255
256	if (btlog->lock_callback)
257	btlog->lock_callback(btlog->callback_context);
258
259	/*
260	* Since the btlog_t anchors the active
261	* list with a pointer to the head of
262	* the list, first loop making sure
263	* the head is correct (and doesn't
264	* match the element being removed).
265	*/
266	recindex = btlog->head;
267	record = lookup_btrecord(btlog, recindex);
268	while (recindex != BTLOG_RECORDINDEX_NONE) {
269	if (record->element == element) {
270	/* remove head of active list */
271	btlog->head = record->next;
272	btlog->activecount--;
273
274	/* add to freelist */
275	record->next = btlog->freelist;
276	btlog->freelist = recindex;
277
278	/* check the new head */
279	recindex = btlog->head;
280	record = lookup_btrecord(btlog, recindex);
281	} else {
282	/* head didn't match, so we can move on */
283	break;
284	}
285	}
286
287	if (recindex == BTLOG_RECORDINDEX_NONE) {
288	/* we iterated over the entire active list removing the element */
289	btlog->tail = BTLOG_RECORDINDEX_NONE;
290	} else {
291	/* the head of the active list is stable, now remove other entries */
292	btlog_recordindex_t precindex = recindex;
293	btlog_record_t *precord = record;
294
295	recindex = precord->next;
296	record = lookup_btrecord(btlog, recindex);
297	while (recindex != BTLOG_RECORDINDEX_NONE) {
298	if (record->element == element) {
299	/* remove in place */
300	precord->next = record->next;
301	btlog->activecount--;
302
303	/* add to freelist */
304	record->next = btlog->freelist;
305	btlog->freelist = recindex;
306
307	/* check the next record */
308	recindex = precord->next;
309	record = lookup_btrecord(btlog, recindex);
310	} else {
311	/* check the next record */
312	precindex = recindex;
313	precord = record;
314
315	recindex = record->next;
316	record = lookup_btrecord(btlog, recindex);
317	}
318	}
319
320	/* We got to the end of the active list. Update the tail */
321	btlog->tail = precindex;
322	}
323
324	if (btlog->unlock_callback)
325	btlog->unlock_callback(btlog->callback_context);
326
327	}