xref: /freebsd/sys/vm/vm_map.h (revision b0d29bc47dba79f6f38e67eabadfb4b32ffd9390)
1 /*-
2  * SPDX-License-Identifier: (BSD-3-Clause AND MIT-CMU)
3  *
4  * Copyright (c) 1991, 1993
5  *	The Regents of the University of California.  All rights reserved.
6  *
7  * This code is derived from software contributed to Berkeley by
8  * The Mach Operating System project at Carnegie-Mellon University.
9  *
10  * Redistribution and use in source and binary forms, with or without
11  * modification, are permitted provided that the following conditions
12  * are met:
13  * 1. Redistributions of source code must retain the above copyright
14  *    notice, this list of conditions and the following disclaimer.
15  * 2. Redistributions in binary form must reproduce the above copyright
16  *    notice, this list of conditions and the following disclaimer in the
17  *    documentation and/or other materials provided with the distribution.
18  * 3. Neither the name of the University nor the names of its contributors
19  *    may be used to endorse or promote products derived from this software
20  *    without specific prior written permission.
21  *
22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32  * SUCH DAMAGE.
33  *
34  *	@(#)vm_map.h	8.9 (Berkeley) 5/17/95
35  *
36  *
37  * Copyright (c) 1987, 1990 Carnegie-Mellon University.
38  * All rights reserved.
39  *
40  * Authors: Avadis Tevanian, Jr., Michael Wayne Young
41  *
42  * Permission to use, copy, modify and distribute this software and
43  * its documentation is hereby granted, provided that both the copyright
44  * notice and this permission notice appear in all copies of the
45  * software, derivative works or modified versions, and any portions
46  * thereof, and that both notices appear in supporting documentation.
47  *
48  * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
49  * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND
50  * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
51  *
52  * Carnegie Mellon requests users of this software to return to
53  *
54  *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
55  *  School of Computer Science
56  *  Carnegie Mellon University
57  *  Pittsburgh PA 15213-3890
58  *
59  * any improvements or extensions that they make and grant Carnegie the
60  * rights to redistribute these changes.
61  *
62  * $FreeBSD$
63  */
64 
65 /*
66  *	Virtual memory map module definitions.
67  */
68 #ifndef	_VM_MAP_
69 #define	_VM_MAP_
70 
71 #include <sys/lock.h>
72 #include <sys/sx.h>
73 #include <sys/_mutex.h>
74 
75 /*
76  *	Types defined:
77  *
78  *	vm_map_t		the high-level address map data structure.
79  *	vm_map_entry_t		an entry in an address map.
80  */
81 
82 typedef u_char vm_flags_t;
83 typedef u_int vm_eflags_t;
84 
85 /*
86  *	Objects which live in maps may be either VM objects, or
87  *	another map (called a "sharing map") which denotes read-write
88  *	sharing with other maps.
89  */
90 union vm_map_object {
91 	struct vm_object *vm_object;	/* object object */
92 	struct vm_map *sub_map;		/* belongs to another map */
93 };
94 
95 /*
96  *	Address map entries consist of start and end addresses,
97  *	a VM object (or sharing map) and offset into that object,
98  *	and user-exported inheritance and protection information.
99  *	Also included is control information for virtual copy operations.
100  */
101 struct vm_map_entry {
102 	struct vm_map_entry *left;	/* left child or previous entry */
103 	struct vm_map_entry *right;	/* right child or next entry */
104 	vm_offset_t start;		/* start address */
105 	vm_offset_t end;		/* end address */
106 	vm_offset_t next_read;		/* vaddr of the next sequential read */
107 	vm_size_t max_free;		/* max free space in subtree */
108 	union vm_map_object object;	/* object I point to */
109 	vm_ooffset_t offset;		/* offset into object */
110 	vm_eflags_t eflags;		/* map entry flags */
111 	vm_prot_t protection;		/* protection code */
112 	vm_prot_t max_protection;	/* maximum protection */
113 	vm_inherit_t inheritance;	/* inheritance */
114 	uint8_t read_ahead;		/* pages in the read-ahead window */
115 	int wired_count;		/* can be paged if = 0 */
116 	struct ucred *cred;		/* tmp storage for creator ref */
117 	struct thread *wiring_thread;
118 };
119 
120 #define	MAP_ENTRY_NOSYNC		0x00000001
121 #define	MAP_ENTRY_IS_SUB_MAP		0x00000002
122 #define	MAP_ENTRY_COW			0x00000004
123 #define	MAP_ENTRY_NEEDS_COPY		0x00000008
124 #define	MAP_ENTRY_NOFAULT		0x00000010
125 #define	MAP_ENTRY_USER_WIRED		0x00000020
126 
127 #define	MAP_ENTRY_BEHAV_NORMAL		0x00000000	/* default behavior */
128 #define	MAP_ENTRY_BEHAV_SEQUENTIAL	0x00000040	/* expect sequential
129 							   access */
130 #define	MAP_ENTRY_BEHAV_RANDOM		0x00000080	/* expect random
131 							   access */
132 #define	MAP_ENTRY_BEHAV_RESERVED	0x000000c0	/* future use */
133 #define	MAP_ENTRY_BEHAV_MASK		0x000000c0
134 #define	MAP_ENTRY_IN_TRANSITION		0x00000100	/* entry being
135 							   changed */
136 #define	MAP_ENTRY_NEEDS_WAKEUP		0x00000200	/* waiters in
137 							   transition */
138 #define	MAP_ENTRY_NOCOREDUMP		0x00000400	/* don't include in
139 							   a core */
140 #define	MAP_ENTRY_VN_EXEC		0x00000800	/* text vnode mapping */
141 #define	MAP_ENTRY_GROWS_DOWN		0x00001000	/* top-down stacks */
142 #define	MAP_ENTRY_GROWS_UP		0x00002000	/* bottom-up stacks */
143 
144 #define	MAP_ENTRY_WIRE_SKIPPED		0x00004000
145 #define	MAP_ENTRY_WRITECNT		0x00008000	/* tracked writeable
146 							   mapping */
147 #define	MAP_ENTRY_GUARD			0x00010000
148 #define	MAP_ENTRY_STACK_GAP_DN		0x00020000
149 #define	MAP_ENTRY_STACK_GAP_UP		0x00040000
150 #define	MAP_ENTRY_HEADER		0x00080000
151 
152 #ifdef	_KERNEL
153 static __inline u_char
154 vm_map_entry_behavior(vm_map_entry_t entry)
155 {
156 	return (entry->eflags & MAP_ENTRY_BEHAV_MASK);
157 }
158 
159 static __inline int
160 vm_map_entry_user_wired_count(vm_map_entry_t entry)
161 {
162 	if (entry->eflags & MAP_ENTRY_USER_WIRED)
163 		return (1);
164 	return (0);
165 }
166 
167 static __inline int
168 vm_map_entry_system_wired_count(vm_map_entry_t entry)
169 {
170 	return (entry->wired_count - vm_map_entry_user_wired_count(entry));
171 }
172 #endif	/* _KERNEL */
173 
174 /*
175  *	A map is a set of map entries.  These map entries are
176  *	organized as a threaded binary search tree.  Both structures
177  *	are ordered based upon the start and end addresses contained
178  *	within each map entry.  The largest gap between an entry in a
179  *	subtree and one of its neighbors is saved in the max_free
180  *	field, and that field is updated when the tree is
181  *	restructured.
182  *
183  *	Sleator and Tarjan's top-down splay algorithm is employed to
184  *	control height imbalance in the binary search tree.
185  *
186  *	The map's min offset value is stored in map->header.end, and
187  *	its max offset value is stored in map->header.start.  These
188  *	values act as sentinels for any forward or backward address
189  *	scan of the list.  The right and left fields of the map
190  *	header point to the first and list map entries.  The map
191  *	header has a special value for the eflags field,
192  *	MAP_ENTRY_HEADER, that is set initially, is never changed,
193  *	and prevents an eflags match of the header with any other map
194  *	entry.
195  *
196  *	List of locks
197  *	(c)	const until freed
198  */
199 struct vm_map {
200 	struct vm_map_entry header;	/* List of entries */
201 	struct sx lock;			/* Lock for map data */
202 	struct mtx system_mtx;
203 	int nentries;			/* Number of entries */
204 	vm_size_t size;			/* virtual size */
205 	u_int timestamp;		/* Version number */
206 	u_char needs_wakeup;
207 	u_char system_map;		/* (c) Am I a system map? */
208 	vm_flags_t flags;		/* flags for this vm_map */
209 	vm_map_entry_t root;		/* Root of a binary search tree */
210 	pmap_t pmap;			/* (c) Physical map */
211 	vm_offset_t anon_loc;
212 	int busy;
213 #ifdef DIAGNOSTIC
214 	int nupdates;
215 #endif
216 };
217 
218 /*
219  * vm_flags_t values
220  */
221 #define MAP_WIREFUTURE		0x01	/* wire all future pages */
222 #define	MAP_BUSY_WAKEUP		0x02
223 #define	MAP_IS_SUB_MAP		0x04	/* has parent */
224 #define	MAP_ASLR		0x08	/* enabled ASLR */
225 #define	MAP_ASLR_IGNSTART	0x10
226 
227 #ifdef	_KERNEL
228 #if defined(KLD_MODULE) && !defined(KLD_TIED)
229 #define	vm_map_max(map)		vm_map_max_KBI((map))
230 #define	vm_map_min(map)		vm_map_min_KBI((map))
231 #define	vm_map_pmap(map)	vm_map_pmap_KBI((map))
232 #else
233 static __inline vm_offset_t
234 vm_map_max(const struct vm_map *map)
235 {
236 
237 	return (map->header.start);
238 }
239 
240 static __inline vm_offset_t
241 vm_map_min(const struct vm_map *map)
242 {
243 
244 	return (map->header.end);
245 }
246 
247 static __inline pmap_t
248 vm_map_pmap(vm_map_t map)
249 {
250 	return (map->pmap);
251 }
252 
253 static __inline void
254 vm_map_modflags(vm_map_t map, vm_flags_t set, vm_flags_t clear)
255 {
256 	map->flags = (map->flags | set) & ~clear;
257 }
258 #endif	/* KLD_MODULE */
259 #endif	/* _KERNEL */
260 
261 /*
262  * Shareable process virtual address space.
263  *
264  * List of locks
265  *	(c)	const until freed
266  */
267 struct vmspace {
268 	struct vm_map vm_map;	/* VM address map */
269 	struct shmmap_state *vm_shm;	/* SYS5 shared memory private data XXX */
270 	segsz_t vm_swrss;	/* resident set size before last swap */
271 	segsz_t vm_tsize;	/* text size (pages) XXX */
272 	segsz_t vm_dsize;	/* data size (pages) XXX */
273 	segsz_t vm_ssize;	/* stack size (pages) */
274 	caddr_t vm_taddr;	/* (c) user virtual address of text */
275 	caddr_t vm_daddr;	/* (c) user virtual address of data */
276 	caddr_t vm_maxsaddr;	/* user VA at max stack growth */
277 	volatile int vm_refcnt;	/* number of references */
278 	/*
279 	 * Keep the PMAP last, so that CPU-specific variations of that
280 	 * structure on a single architecture don't result in offset
281 	 * variations of the machine-independent fields in the vmspace.
282 	 */
283 	struct pmap vm_pmap;	/* private physical map */
284 };
285 
286 #ifdef	_KERNEL
287 static __inline pmap_t
288 vmspace_pmap(struct vmspace *vmspace)
289 {
290 	return &vmspace->vm_pmap;
291 }
292 #endif	/* _KERNEL */
293 
294 #ifdef	_KERNEL
295 /*
296  *	Macros:		vm_map_lock, etc.
297  *	Function:
298  *		Perform locking on the data portion of a map.  Note that
299  *		these macros mimic procedure calls returning void.  The
300  *		semicolon is supplied by the user of these macros, not
301  *		by the macros themselves.  The macros can safely be used
302  *		as unbraced elements in a higher level statement.
303  */
304 
305 void _vm_map_lock(vm_map_t map, const char *file, int line);
306 void _vm_map_unlock(vm_map_t map, const char *file, int line);
307 int _vm_map_unlock_and_wait(vm_map_t map, int timo, const char *file, int line);
308 void _vm_map_lock_read(vm_map_t map, const char *file, int line);
309 void _vm_map_unlock_read(vm_map_t map, const char *file, int line);
310 int _vm_map_trylock(vm_map_t map, const char *file, int line);
311 int _vm_map_trylock_read(vm_map_t map, const char *file, int line);
312 int _vm_map_lock_upgrade(vm_map_t map, const char *file, int line);
313 void _vm_map_lock_downgrade(vm_map_t map, const char *file, int line);
314 int vm_map_locked(vm_map_t map);
315 void vm_map_wakeup(vm_map_t map);
316 void vm_map_busy(vm_map_t map);
317 void vm_map_unbusy(vm_map_t map);
318 void vm_map_wait_busy(vm_map_t map);
319 vm_offset_t vm_map_max_KBI(const struct vm_map *map);
320 vm_offset_t vm_map_min_KBI(const struct vm_map *map);
321 pmap_t vm_map_pmap_KBI(vm_map_t map);
322 
323 #define	vm_map_lock(map)	_vm_map_lock(map, LOCK_FILE, LOCK_LINE)
324 #define	vm_map_unlock(map)	_vm_map_unlock(map, LOCK_FILE, LOCK_LINE)
325 #define	vm_map_unlock_and_wait(map, timo)	\
326 			_vm_map_unlock_and_wait(map, timo, LOCK_FILE, LOCK_LINE)
327 #define	vm_map_lock_read(map)	_vm_map_lock_read(map, LOCK_FILE, LOCK_LINE)
328 #define	vm_map_unlock_read(map)	_vm_map_unlock_read(map, LOCK_FILE, LOCK_LINE)
329 #define	vm_map_trylock(map)	_vm_map_trylock(map, LOCK_FILE, LOCK_LINE)
330 #define	vm_map_trylock_read(map)	\
331 			_vm_map_trylock_read(map, LOCK_FILE, LOCK_LINE)
332 #define	vm_map_lock_upgrade(map)	\
333 			_vm_map_lock_upgrade(map, LOCK_FILE, LOCK_LINE)
334 #define	vm_map_lock_downgrade(map)	\
335 			_vm_map_lock_downgrade(map, LOCK_FILE, LOCK_LINE)
336 
337 long vmspace_resident_count(struct vmspace *vmspace);
338 #endif	/* _KERNEL */
339 
340 
341 /* XXX: number of kernel maps to statically allocate */
342 #define MAX_KMAP	10
343 
344 /*
345  * Copy-on-write flags for vm_map operations
346  */
347 #define	MAP_INHERIT_SHARE	0x00000001
348 #define	MAP_COPY_ON_WRITE	0x00000002
349 #define	MAP_NOFAULT		0x00000004
350 #define	MAP_PREFAULT		0x00000008
351 #define	MAP_PREFAULT_PARTIAL	0x00000010
352 #define	MAP_DISABLE_SYNCER	0x00000020
353 #define	MAP_CHECK_EXCL		0x00000040
354 #define	MAP_CREATE_GUARD	0x00000080
355 #define	MAP_DISABLE_COREDUMP	0x00000100
356 #define	MAP_PREFAULT_MADVISE	0x00000200    /* from (user) madvise request */
357 #define	MAP_WRITECOUNT		0x00000400
358 #define	MAP_REMAP		0x00000800
359 #define	MAP_STACK_GROWS_DOWN	0x00001000
360 #define	MAP_STACK_GROWS_UP	0x00002000
361 #define	MAP_ACC_CHARGED		0x00004000
362 #define	MAP_ACC_NO_CHARGE	0x00008000
363 #define	MAP_CREATE_STACK_GAP_UP	0x00010000
364 #define	MAP_CREATE_STACK_GAP_DN	0x00020000
365 #define	MAP_VN_EXEC		0x00040000
366 
367 /*
368  * vm_fault option flags
369  */
370 #define	VM_FAULT_NORMAL	0		/* Nothing special */
371 #define	VM_FAULT_WIRE	1		/* Wire the mapped page */
372 #define	VM_FAULT_DIRTY	2		/* Dirty the page; use w/VM_PROT_COPY */
373 
374 /*
375  * Initially, mappings are slightly sequential.  The maximum window size must
376  * account for the map entry's "read_ahead" field being defined as an uint8_t.
377  */
378 #define	VM_FAULT_READ_AHEAD_MIN		7
379 #define	VM_FAULT_READ_AHEAD_INIT	15
380 #define	VM_FAULT_READ_AHEAD_MAX		min(atop(MAXPHYS) - 1, UINT8_MAX)
381 
382 /*
383  * The following "find_space" options are supported by vm_map_find().
384  *
385  * For VMFS_ALIGNED_SPACE, the desired alignment is specified to
386  * the macro argument as log base 2 of the desired alignment.
387  */
388 #define	VMFS_NO_SPACE		0	/* don't find; use the given range */
389 #define	VMFS_ANY_SPACE		1	/* find a range with any alignment */
390 #define	VMFS_OPTIMAL_SPACE	2	/* find a range with optimal alignment*/
391 #define	VMFS_SUPER_SPACE	3	/* find a superpage-aligned range */
392 #define	VMFS_ALIGNED_SPACE(x)	((x) << 8) /* find a range with fixed alignment */
393 
394 /*
395  * vm_map_wire and vm_map_unwire option flags
396  */
397 #define VM_MAP_WIRE_SYSTEM	0	/* wiring in a kernel map */
398 #define VM_MAP_WIRE_USER	1	/* wiring in a user map */
399 
400 #define VM_MAP_WIRE_NOHOLES	0	/* region must not have holes */
401 #define VM_MAP_WIRE_HOLESOK	2	/* region may have holes */
402 
403 #define VM_MAP_WIRE_WRITE	4	/* Validate writable. */
404 
405 typedef int vm_map_entry_reader(void *token, vm_map_entry_t addr,
406     vm_map_entry_t dest);
407 
408 #ifndef _KERNEL
409 /*
410  * Find the successor of a map_entry, using a reader to dereference pointers.
411  * '*clone' is a copy of a vm_map entry.  'reader' is used to copy a map entry
412  * at some address into '*clone'.  Change *clone to a copy of the next map
413  * entry, and return the address of that entry, or NULL if copying has failed.
414  *
415  * This function is made available to user-space code that needs to traverse
416  * map entries.
417  */
418 static inline vm_map_entry_t
419 vm_map_entry_read_succ(void *token, struct vm_map_entry *const clone,
420     vm_map_entry_reader reader)
421 {
422 	vm_map_entry_t after, backup;
423 	vm_offset_t start;
424 
425 	after = clone->right;
426 	start = clone->start;
427 	if (!reader(token, after, clone))
428 		return (NULL);
429 	backup = clone->left;
430 	if (!reader(token, backup, clone))
431 		return (NULL);
432 	if (clone->start > start) {
433 		do {
434 			after = backup;
435 			backup = clone->left;
436 			if (!reader(token, backup, clone))
437 				return (NULL);
438 		} while (clone->start != start);
439 	}
440 	if (!reader(token, after, clone))
441 		return (NULL);
442 	return (after);
443 }
444 #endif				/* ! _KERNEL */
445 
446 #ifdef _KERNEL
447 boolean_t vm_map_check_protection (vm_map_t, vm_offset_t, vm_offset_t, vm_prot_t);
448 vm_map_t vm_map_create(pmap_t, vm_offset_t, vm_offset_t);
449 int vm_map_delete(vm_map_t, vm_offset_t, vm_offset_t);
450 int vm_map_find(vm_map_t, vm_object_t, vm_ooffset_t, vm_offset_t *, vm_size_t,
451     vm_offset_t, int, vm_prot_t, vm_prot_t, int);
452 int vm_map_find_min(vm_map_t, vm_object_t, vm_ooffset_t, vm_offset_t *,
453     vm_size_t, vm_offset_t, vm_offset_t, int, vm_prot_t, vm_prot_t, int);
454 int vm_map_fixed(vm_map_t, vm_object_t, vm_ooffset_t, vm_offset_t, vm_size_t,
455     vm_prot_t, vm_prot_t, int);
456 vm_offset_t vm_map_findspace(vm_map_t, vm_offset_t, vm_size_t);
457 int vm_map_inherit (vm_map_t, vm_offset_t, vm_offset_t, vm_inherit_t);
458 void vm_map_init(vm_map_t, pmap_t, vm_offset_t, vm_offset_t);
459 int vm_map_insert (vm_map_t, vm_object_t, vm_ooffset_t, vm_offset_t, vm_offset_t, vm_prot_t, vm_prot_t, int);
460 int vm_map_lookup (vm_map_t *, vm_offset_t, vm_prot_t, vm_map_entry_t *, vm_object_t *,
461     vm_pindex_t *, vm_prot_t *, boolean_t *);
462 int vm_map_lookup_locked(vm_map_t *, vm_offset_t, vm_prot_t, vm_map_entry_t *, vm_object_t *,
463     vm_pindex_t *, vm_prot_t *, boolean_t *);
464 void vm_map_lookup_done (vm_map_t, vm_map_entry_t);
465 boolean_t vm_map_lookup_entry (vm_map_t, vm_offset_t, vm_map_entry_t *);
466 
467 static inline vm_map_entry_t
468 vm_map_entry_first(vm_map_t map)
469 {
470 
471 	return (map->header.right);
472 }
473 
474 static inline vm_map_entry_t
475 vm_map_entry_succ(vm_map_entry_t entry)
476 {
477 	vm_map_entry_t after;
478 
479 	after = entry->right;
480 	if (after->left->start > entry->start) {
481 		do
482 			after = after->left;
483 		while (after->left != entry);
484 	}
485 	return (after);
486 }
487 
488 #define VM_MAP_ENTRY_FOREACH(it, map)		\
489 	for ((it) = vm_map_entry_first(map);	\
490 	    (it) != &(map)->header;		\
491 	    (it) = vm_map_entry_succ(it))
492 int vm_map_protect (vm_map_t, vm_offset_t, vm_offset_t, vm_prot_t, boolean_t);
493 int vm_map_remove (vm_map_t, vm_offset_t, vm_offset_t);
494 void vm_map_try_merge_entries(vm_map_t map, vm_map_entry_t prev,
495     vm_map_entry_t entry);
496 void vm_map_startup (void);
497 int vm_map_submap (vm_map_t, vm_offset_t, vm_offset_t, vm_map_t);
498 int vm_map_sync(vm_map_t, vm_offset_t, vm_offset_t, boolean_t, boolean_t);
499 int vm_map_madvise (vm_map_t, vm_offset_t, vm_offset_t, int);
500 int vm_map_stack (vm_map_t, vm_offset_t, vm_size_t, vm_prot_t, vm_prot_t, int);
501 int vm_map_unwire(vm_map_t map, vm_offset_t start, vm_offset_t end,
502     int flags);
503 int vm_map_wire(vm_map_t map, vm_offset_t start, vm_offset_t end, int flags);
504 int vm_map_wire_locked(vm_map_t map, vm_offset_t start, vm_offset_t end,
505     int flags);
506 long vmspace_swap_count(struct vmspace *vmspace);
507 void vm_map_entry_set_vnode_text(vm_map_entry_t entry, bool add);
508 #endif				/* _KERNEL */
509 #endif				/* _VM_MAP_ */
510