1/* $NetBSD: uvm_page.h,v 1.109 2020/12/20 16:38:26 skrll Exp $ */
2
3/*
4 * Copyright (c) 1997 Charles D. Cranor and Washington University.
5 * Copyright (c) 1991, 1993, The Regents of the University of California.
6 *
7 * All rights reserved.
8 *
9 * This code is derived from software contributed to Berkeley by
10 * The Mach Operating System project at Carnegie-Mellon University.
11 *
12 * Redistribution and use in source and binary forms, with or without
13 * modification, are permitted provided that the following conditions
14 * are met:
15 * 1. Redistributions of source code must retain the above copyright
16 * notice, this list of conditions and the following disclaimer.
17 * 2. Redistributions in binary form must reproduce the above copyright
18 * notice, this list of conditions and the following disclaimer in the
19 * documentation and/or other materials provided with the distribution.
20 * 3. Neither the name of the University nor the names of its contributors
21 * may be used to endorse or promote products derived from this software
22 * without specific prior written permission.
23 *
24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34 * SUCH DAMAGE.
35 *
36 * @(#)vm_page.h 7.3 (Berkeley) 4/21/91
37 * from: Id: uvm_page.h,v 1.1.2.6 1998/02/04 02:31:42 chuck Exp
38 *
39 *
40 * Copyright (c) 1987, 1990 Carnegie-Mellon University.
41 * All rights reserved.
42 *
43 * Permission to use, copy, modify and distribute this software and
44 * its documentation is hereby granted, provided that both the copyright
45 * notice and this permission notice appear in all copies of the
46 * software, derivative works or modified versions, and any portions
47 * thereof, and that both notices appear in supporting documentation.
48 *
49 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
50 * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND
51 * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
52 *
53 * Carnegie Mellon requests users of this software to return to
54 *
55 * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
56 * School of Computer Science
57 * Carnegie Mellon University
58 * Pittsburgh PA 15213-3890
59 *
60 * any improvements or extensions that they make and grant Carnegie the
61 * rights to redistribute these changes.
62 */
63
64#ifndef _UVM_UVM_PAGE_H_
65#define _UVM_UVM_PAGE_H_
66
67#ifdef _KERNEL_OPT
68#include "opt_uvm_page_trkown.h"
69#endif
70
71#include <sys/rwlock.h>
72
73#include <uvm/uvm_extern.h>
74#include <uvm/uvm_pglist.h>
75
76/*
77 * Management of resident (logical) pages.
78 *
79 * Each resident page has a vm_page structure, indexed by page number.
80 * There are several lists in the structure:
81 *
82 * - A red-black tree rooted with the containing object is used to
83 * quickly perform object+offset lookups.
84 * - A list of all pages for a given object, for a quick deactivation
85 * at a time of deallocation.
86 * - An ordered list of pages due for pageout.
87 *
88 * In addition, the structure contains the object and offset to which
89 * this page belongs (for pageout) and sundry status bits.
90 *
91 * Note that the page structure has no lock of its own. The page is
92 * generally protected by its owner's lock (UVM object or amap/anon).
93 * It should be noted that UVM has to serialize pmap(9) operations on
94 * the managed pages, e.g. for pmap_enter() calls. Hence, the lock
95 * order is as follows:
96 *
97 * [vmpage-owner-lock] ->
98 * any pmap locks (e.g. PV hash lock)
99 *
100 * Since the kernel is always self-consistent, no serialization is
101 * required for unmanaged mappings, e.g. for pmap_kenter_pa() calls.
102 *
103 * Field markings and the corresponding locks:
104 *
105 * f: free page queue lock, uvm_fpageqlock
106 * o: page owner (uvm_object::vmobjlock, vm_amap::am_lock, vm_anon::an_lock)
107 * i: vm_page::interlock
108 * => flags set and cleared only with o&i held can
109 * safely be tested for with only o held.
110 * o,i: o|i for read, o&i for write (depends on context - if could be loaned)
111 * => see uvm_loan.c
112 * w: wired page queue or uvm_pglistalloc:
113 * => wired page queue: o&i to change, stable from wire to unwire
114 * XXX What about concurrent or nested wire?
115 * => uvm_pglistalloc: owned by caller
116 * ?: locked by pmap or assumed page owner's lock
117 * p: locked by pagedaemon policy module (pdpolicy)
118 * c: cpu private
119 * s: stable, does not change
120 *
121 * UVM and pmap(9) may use uvm_page_owner_locked_p() to assert whether the
122 * page owner's lock is acquired.
123 *
124 * A page can have one of four identities:
125 *
126 * o free
127 * => pageq.list is entry on global free page queue
128 * => uanon is unused (or (void *)0xdeadbeef for DEBUG)
129 * => uobject is unused (or (void *)0xdeadbeef for DEBUG)
130 * => PG_FREE is set in flags
131 * o owned by a uvm_object
132 * => pageq.queue is entry on wired page queue, if any
133 * => uanon is NULL or the vm_anon to which it has been O->A loaned
134 * => uobject is owner
135 * o owned by a vm_anon
136 * => pageq is unused (XXX correct?)
137 * => uanon is owner
138 * => uobject is NULL
139 * => PG_ANON is set in flags
140 * o allocated by uvm_pglistalloc
141 * => pageq.queue is entry on resulting pglist, owned by caller
142 * => uanon is unused
143 * => uobject is unused
144 *
145 * The following transitions are allowed:
146 *
147 * - uvm_pagealloc: free -> owned by a uvm_object/vm_anon
148 * - uvm_pagefree: owned by a uvm_object/vm_anon -> free
149 * - uvm_pglistalloc: free -> allocated by uvm_pglistalloc
150 * - uvm_pglistfree: allocated by uvm_pglistalloc -> free
151 *
152 * On the ordering of fields:
153 *
154 * The fields most heavily used during fault processing are clustered
155 * together at the start of the structure to reduce cache misses.
156 * XXX This entire thing should be shrunk to fit in one cache line.
157 */
158
159struct vm_page {
160 /* _LP64: first cache line */
161 union {
162 TAILQ_ENTRY(vm_page) queue; /* w: wired page queue
163 * or uvm_pglistalloc output */
164 LIST_ENTRY(vm_page) list; /* f: global free page queue */
165 } pageq;
166 uint32_t pqflags; /* i: pagedaemon flags */
167 uint32_t flags; /* o: object flags */
168 paddr_t phys_addr; /* o: physical address of pg */
169 uint32_t loan_count; /* o,i: num. active loans */
170 uint32_t wire_count; /* o,i: wired down map refs */
171 struct vm_anon *uanon; /* o,i: anon */
172 struct uvm_object *uobject; /* o,i: object */
173 voff_t offset; /* o: offset into object */
174
175 /* _LP64: second cache line */
176 kmutex_t interlock; /* s: lock on identity */
177 TAILQ_ENTRY(vm_page) pdqueue; /* p: pagedaemon queue */
178
179#ifdef __HAVE_VM_PAGE_MD
180 struct vm_page_md mdpage; /* ?: pmap-specific data */
181#endif
182
183#if defined(UVM_PAGE_TRKOWN)
184 /* debugging fields to track page ownership */
185 pid_t owner; /* proc that set PG_BUSY */
186 lwpid_t lowner; /* lwp that set PG_BUSY */
187 const char *owner_tag; /* why it was set busy */
188#endif
189};
190
191/*
192 * Overview of UVM page flags, stored in pg->flags.
193 *
194 * Locking notes:
195 *
196 * PG_, struct vm_page::flags => locked by owner
197 * PG_AOBJ => additionally locked by vm_page::interlock
198 * PG_ANON => additionally locked by vm_page::interlock
199 * PG_FREE => additionally locked by uvm_fpageqlock
200 * for uvm_pglistalloc()
201 *
202 * Flag descriptions:
203 *
204 * PG_CLEAN:
205 * Page is known clean.
206 * The contents of the page is consistent with its backing store.
207 *
208 * PG_DIRTY:
209 * Page is known dirty.
210 * To avoid losing data, the contents of the page should be written
211 * back to the backing store before freeing the page.
212 *
213 * PG_BUSY:
214 * Page is long-term locked, usually because of I/O (transfer from the
215 * page memory to the backing store) is in progress. LWP attempting
216 * to access the page shall set PQ_WANTED and wait. PG_BUSY may only
217 * be set with a write lock held on the object.
218 *
219 * PG_PAGEOUT:
220 * Indicates that the page is being paged-out in preparation for
221 * being freed.
222 *
223 * PG_RELEASED:
224 * Indicates that the page, which is currently PG_BUSY, should be freed
225 * after the release of long-term lock. It is responsibility of the
226 * owning LWP (i.e. which set PG_BUSY) to do it.
227 *
228 * PG_FAKE:
229 * Page has been allocated, but not yet initialised. The flag is used
230 * to avoid overwriting of valid data, e.g. to prevent read from the
231 * backing store when in-core data is newer.
232 *
233 * PG_RDONLY:
234 * Indicates that the page must be mapped read-only.
235 *
236 * PG_MARKER:
237 * Dummy marker page, generally used for list traversal.
238 */
239
240/*
241 * if you want to renumber PG_CLEAN and PG_DIRTY, check __CTASSERTs in
242 * uvm_page_status.c first.
243 */
244
245#define PG_CLEAN 0x00000001 /* page is known clean */
246#define PG_DIRTY 0x00000002 /* page is known dirty */
247#define PG_BUSY 0x00000004 /* page is locked */
248#define PG_PAGEOUT 0x00000010 /* page to be freed for pagedaemon */
249#define PG_RELEASED 0x00000020 /* page to be freed when unbusied */
250#define PG_FAKE 0x00000040 /* page is not yet initialized */
251#define PG_RDONLY 0x00000080 /* page must be mapped read-only */
252#define PG_TABLED 0x00000200 /* page is tabled in object */
253#define PG_AOBJ 0x00000400 /* page is part of an anonymous
254 uvm_object */
255#define PG_ANON 0x00000800 /* page is part of an anon, rather
256 than an uvm_object */
257#define PG_FILE 0x00001000 /* file backed (non-anonymous) */
258#define PG_READAHEAD 0x00002000 /* read-ahead but not "hit" yet */
259#define PG_FREE 0x00004000 /* page is on free list */
260#define PG_MARKER 0x00008000 /* dummy marker page */
261#define PG_PAGER1 0x00010000 /* pager-specific flag */
262#define PG_PGLCA 0x00020000 /* allocated by uvm_pglistalloc_contig */
263
264#define PG_STAT (PG_ANON|PG_AOBJ|PG_FILE)
265#define PG_SWAPBACKED (PG_ANON|PG_AOBJ)
266
267#define UVM_PGFLAGBITS \
268 "\20\1CLEAN\2DIRTY\3BUSY" \
269 "\5PAGEOUT\6RELEASED\7FAKE\10RDONLY" \
270 "\11ZERO\12TABLED\13AOBJ\14ANON" \
271 "\15FILE\16READAHEAD\17FREE\20MARKER" \
272 "\21PAGER1\22PGLCA"
273
274/*
275 * Flags stored in pg->pqflags, which is protected by pg->interlock.
276 *
277 * PQ_PRIVATE:
278 * ... is for uvmpdpol to do whatever it wants with.
279 *
280 * PQ_INTENT_SET:
281 * Indicates that the intent set on the page has not yet been realized.
282 *
283 * PQ_INTENT_QUEUED:
284 * Indicates that the page is, or will soon be, on a per-CPU queue for
285 * the intent to be realized.
286 *
287 * PQ_WANTED:
288 * Indicates that the page, which is currently PG_BUSY, is wanted by
289 * some other LWP. The page owner (i.e. LWP which set PG_BUSY) is
290 * responsible to clear both flags and wake up any waiters once it has
291 * released the long-term lock (PG_BUSY).
292 */
293
294#define PQ_INTENT_A 0x00000000 /* intend activation */
295#define PQ_INTENT_I 0x00000001 /* intend deactivation */
296#define PQ_INTENT_E 0x00000002 /* intend enqueue */
297#define PQ_INTENT_D 0x00000003 /* intend dequeue */
298#define PQ_INTENT_MASK 0x00000003 /* mask of intended state */
299#define PQ_INTENT_SET 0x00000004 /* not realized yet */
300#define PQ_INTENT_QUEUED 0x00000008 /* queued for processing */
301#define PQ_PRIVATE 0x00000ff0 /* private for pdpolicy */
302#define PQ_WANTED 0x00001000 /* someone is waiting for page */
303
304#define UVM_PQFLAGBITS \
305 "\20\1INTENT_0\2INTENT_1\3INTENT_SET\4INTENT_QUEUED" \
306 "\5PRIVATE1\6PRIVATE2\7PRIVATE3\10PRIVATE4" \
307 "\11PRIVATE5\12PRIVATE6\13PRIVATE7\14PRIVATE8" \
308 "\15WANTED"
309
310/*
311 * physical memory layout structure
312 *
313 * MD vmparam.h must #define:
314 * VM_PHYSEG_MAX = max number of physical memory segments we support
315 * (if this is "1" then we revert to a "contig" case)
316 * VM_PHYSSEG_STRAT: memory sort/search options (for VM_PHYSEG_MAX > 1)
317 * - VM_PSTRAT_RANDOM: linear search (random order)
318 * - VM_PSTRAT_BSEARCH: binary search (sorted by address)
319 * - VM_PSTRAT_BIGFIRST: linear search (sorted by largest segment first)
320 * - others?
321 * XXXCDC: eventually we should purge all left-over global variables...
322 */
323#define VM_PSTRAT_RANDOM 1
324#define VM_PSTRAT_BSEARCH 2
325#define VM_PSTRAT_BIGFIRST 3
326
327#ifdef _KERNEL
328
329/*
330 * prototypes: the following prototypes define the interface to pages
331 */
332
333void uvm_page_init(vaddr_t *, vaddr_t *);
334void uvm_pglistalloc_init(void);
335#if defined(UVM_PAGE_TRKOWN)
336void uvm_page_own(struct vm_page *, const char *);
337#endif
338#if !defined(PMAP_STEAL_MEMORY)
339bool uvm_page_physget(paddr_t *);
340#endif
341void uvm_page_recolor(int);
342void uvm_page_rebucket(void);
343
344void uvm_pageactivate(struct vm_page *);
345vaddr_t uvm_pageboot_alloc(vsize_t);
346void uvm_pagecopy(struct vm_page *, struct vm_page *);
347void uvm_pagedeactivate(struct vm_page *);
348void uvm_pagedequeue(struct vm_page *);
349void uvm_pageenqueue(struct vm_page *);
350void uvm_pagefree(struct vm_page *);
351void uvm_pagelock(struct vm_page *);
352void uvm_pagelock2(struct vm_page *, struct vm_page *);
353void uvm_pageunlock(struct vm_page *);
354void uvm_pageunlock2(struct vm_page *, struct vm_page *);
355void uvm_page_unbusy(struct vm_page **, int);
356struct vm_page *uvm_pagelookup(struct uvm_object *, voff_t);
357void uvm_pageunwire(struct vm_page *);
358void uvm_pagewire(struct vm_page *);
359void uvm_pagezero(struct vm_page *);
360bool uvm_pageismanaged(paddr_t);
361bool uvm_page_owner_locked_p(struct vm_page *, bool);
362void uvm_pgfl_lock(void);
363void uvm_pgfl_unlock(void);
364unsigned int uvm_pagegetdirty(struct vm_page *);
365void uvm_pagemarkdirty(struct vm_page *, unsigned int);
366bool uvm_pagecheckdirty(struct vm_page *, bool);
367bool uvm_pagereadonly_p(struct vm_page *);
368bool uvm_page_locked_p(struct vm_page *);
369void uvm_pagewakeup(struct vm_page *);
370bool uvm_pagewanted_p(struct vm_page *);
371void uvm_pagewait(struct vm_page *, krwlock_t *, const char *);
372
373int uvm_page_lookup_freelist(struct vm_page *);
374
375struct vm_page *uvm_phys_to_vm_page(paddr_t);
376paddr_t uvm_vm_page_to_phys(const struct vm_page *);
377
378#if defined(PMAP_DIRECT)
379extern bool ubc_direct;
380int uvm_direct_process(struct vm_page **, u_int, voff_t, vsize_t,
381 int (*)(void *, size_t, void *), void *);
382#endif
383
384/*
385 * page dirtiness status for uvm_pagegetdirty and uvm_pagemarkdirty
386 *
387 * UNKNOWN means that we need to consult pmap to know if the page is
388 * dirty or not.
389 * basically, UVM_PAGE_STATUS_CLEAN implies that the page has no writable
390 * mapping.
391 *
392 * if you want to renumber these, check __CTASSERTs in
393 * uvm_page_status.c first.
394 */
395
396#define UVM_PAGE_STATUS_UNKNOWN 0
397#define UVM_PAGE_STATUS_CLEAN 1
398#define UVM_PAGE_STATUS_DIRTY 2
399#define UVM_PAGE_NUM_STATUS 3
400
401/*
402 * macros
403 */
404
405#define VM_PAGE_TO_PHYS(entry) uvm_vm_page_to_phys(entry)
406
407#ifdef __HAVE_VM_PAGE_MD
408#define VM_PAGE_TO_MD(pg) (&(pg)->mdpage)
409#define VM_MD_TO_PAGE(md) (container_of((md), struct vm_page, mdpage))
410#endif
411
412/*
413 * Compute the page color for a given page.
414 */
415#define VM_PGCOLOR(pg) \
416 (atop(VM_PAGE_TO_PHYS((pg))) & uvmexp.colormask)
417#define PHYS_TO_VM_PAGE(pa) uvm_phys_to_vm_page(pa)
418
419/*
420 * VM_PAGE_IS_FREE() can't tell if the page is on global free list, or a
421 * per-CPU cache. If you need to be certain, pause caching.
422 */
423#define VM_PAGE_IS_FREE(entry) ((entry)->flags & PG_FREE)
424
425/*
426 * Use the lower 10 bits of pg->phys_addr to cache some some locators for
427 * the page. This implies that the smallest possible page size is 1kB, and
428 * that nobody should use pg->phys_addr directly (use VM_PAGE_TO_PHYS()).
429 *
430 * - 5 bits for the freelist index, because uvm_page_lookup_freelist()
431 * traverses an rbtree and therefore features prominently in traces
432 * captured during performance test. It would probably be more useful to
433 * cache physseg index here because freelist can be inferred from physseg,
434 * but it requires changes to allocation for UVM_HOTPLUG, so for now we'll
435 * go with freelist.
436 *
437 * - 5 bits for "bucket", a way for us to categorise pages further as
438 * needed (e.g. NUMA node).
439 *
440 * None of this is set in stone; it can be adjusted as needed.
441 */
442
443#define UVM_PHYSADDR_FREELIST __BITS(0,4)
444#define UVM_PHYSADDR_BUCKET __BITS(5,9)
445
446static inline unsigned
447uvm_page_get_freelist(struct vm_page *pg)
448{
449 unsigned fl = __SHIFTOUT(pg->phys_addr, UVM_PHYSADDR_FREELIST);
450 KASSERT(fl == (unsigned)uvm_page_lookup_freelist(pg));
451 return fl;
452}
453
454static inline unsigned
455uvm_page_get_bucket(struct vm_page *pg)
456{
457 return __SHIFTOUT(pg->phys_addr, UVM_PHYSADDR_BUCKET);
458}
459
460static inline void
461uvm_page_set_freelist(struct vm_page *pg, unsigned fl)
462{
463 KASSERT(fl < 32);
464 pg->phys_addr &= ~UVM_PHYSADDR_FREELIST;
465 pg->phys_addr |= __SHIFTIN(fl, UVM_PHYSADDR_FREELIST);
466}
467
468static inline void
469uvm_page_set_bucket(struct vm_page *pg, unsigned b)
470{
471 KASSERT(b < 32);
472 pg->phys_addr &= ~UVM_PHYSADDR_BUCKET;
473 pg->phys_addr |= __SHIFTIN(b, UVM_PHYSADDR_BUCKET);
474}
475
476#endif /* _KERNEL */
477
478#endif /* _UVM_UVM_PAGE_H_ */