kernel - MPSAFE work - Finish tokenizing vm_page.c
[dragonfly.git] / sys / vm / vm_fault.c
CommitLineData
984263bc 1/*
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2 * (MPSAFE)
3 *
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4 * Copyright (c) 1991, 1993
5 * The Regents of the University of California. All rights reserved.
6 * Copyright (c) 1994 John S. Dyson
7 * All rights reserved.
8 * Copyright (c) 1994 David Greenman
9 * All rights reserved.
10 *
11 *
12 * This code is derived from software contributed to Berkeley by
13 * The Mach Operating System project at Carnegie-Mellon University.
14 *
15 * Redistribution and use in source and binary forms, with or without
16 * modification, are permitted provided that the following conditions
17 * are met:
18 * 1. Redistributions of source code must retain the above copyright
19 * notice, this list of conditions and the following disclaimer.
20 * 2. Redistributions in binary form must reproduce the above copyright
21 * notice, this list of conditions and the following disclaimer in the
22 * documentation and/or other materials provided with the distribution.
23 * 3. All advertising materials mentioning features or use of this software
24 * must display the following acknowledgement:
25 * This product includes software developed by the University of
26 * California, Berkeley and its contributors.
27 * 4. Neither the name of the University nor the names of its contributors
28 * may be used to endorse or promote products derived from this software
29 * without specific prior written permission.
30 *
31 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
32 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
33 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
34 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
35 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
36 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
37 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
38 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
39 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
40 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
41 * SUCH DAMAGE.
42 *
43 * from: @(#)vm_fault.c 8.4 (Berkeley) 1/12/94
44 *
45 *
46 * Copyright (c) 1987, 1990 Carnegie-Mellon University.
47 * All rights reserved.
48 *
49 * Authors: Avadis Tevanian, Jr., Michael Wayne Young
50 *
51 * Permission to use, copy, modify and distribute this software and
52 * its documentation is hereby granted, provided that both the copyright
53 * notice and this permission notice appear in all copies of the
54 * software, derivative works or modified versions, and any portions
55 * thereof, and that both notices appear in supporting documentation.
56 *
57 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
58 * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND
59 * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
60 *
61 * Carnegie Mellon requests users of this software to return to
62 *
63 * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
64 * School of Computer Science
65 * Carnegie Mellon University
66 * Pittsburgh PA 15213-3890
67 *
68 * any improvements or extensions that they make and grant Carnegie the
69 * rights to redistribute these changes.
70 *
71 * $FreeBSD: src/sys/vm/vm_fault.c,v 1.108.2.8 2002/02/26 05:49:27 silby Exp $
4ecf7cc9 72 * $DragonFly: src/sys/vm/vm_fault.c,v 1.47 2008/07/01 02:02:56 dillon Exp $
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73 */
74
75/*
76 * Page fault handling module.
77 */
78
79#include <sys/param.h>
80#include <sys/systm.h>
46311ac2 81#include <sys/kernel.h>
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82#include <sys/proc.h>
83#include <sys/vnode.h>
84#include <sys/resourcevar.h>
85#include <sys/vmmeter.h>
75f59a66 86#include <sys/vkernel.h>
75f59a66 87#include <sys/lock.h>
bc823b32 88#include <sys/sysctl.h>
984263bc 89
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90#include <cpu/lwbuf.h>
91
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92#include <vm/vm.h>
93#include <vm/vm_param.h>
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94#include <vm/pmap.h>
95#include <vm/vm_map.h>
96#include <vm/vm_object.h>
97#include <vm/vm_page.h>
98#include <vm/vm_pageout.h>
99#include <vm/vm_kern.h>
100#include <vm/vm_pager.h>
101#include <vm/vnode_pager.h>
102#include <vm/vm_extern.h>
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103
104#include <sys/thread2.h>
12e4aaff 105#include <vm/vm_page2.h>
984263bc 106
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107struct faultstate {
108 vm_page_t m;
109 vm_object_t object;
110 vm_pindex_t pindex;
72579d2e 111 vm_prot_t prot;
984263bc 112 vm_page_t first_m;
568e6804 113 vm_object_t first_object;
72579d2e 114 vm_prot_t first_prot;
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115 vm_map_t map;
116 vm_map_entry_t entry;
117 int lookup_still_valid;
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118 int didlimit;
119 int hardfault;
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120 int fault_flags;
121 int map_generation;
122 boolean_t wired;
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123 struct vnode *vp;
124};
125
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126static int vm_fast_fault = 1;
127SYSCTL_INT(_vm, OID_AUTO, fast_fault, CTLFLAG_RW, &vm_fast_fault, 0, "");
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128static int debug_cluster = 0;
129SYSCTL_INT(_vm, OID_AUTO, debug_cluster, CTLFLAG_RW, &debug_cluster, 0, "");
bc823b32 130
72579d2e 131static int vm_fault_object(struct faultstate *, vm_pindex_t, vm_prot_t);
4e7c41c5 132static int vm_fault_vpagetable(struct faultstate *, vm_pindex_t *, vpte_t, int);
1b9d3514 133#if 0
568e6804 134static int vm_fault_additional_pages (vm_page_t, int, int, vm_page_t *, int *);
1b9d3514 135#endif
72579d2e 136static int vm_fault_ratelimit(struct vmspace *);
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137static void vm_prefault(pmap_t pmap, vm_offset_t addra, vm_map_entry_t entry,
138 int prot);
568e6804 139
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140/*
141 * The caller must hold vm_token.
142 */
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143static __inline void
144release_page(struct faultstate *fs)
145{
984263bc 146 vm_page_deactivate(fs->m);
17cde63e 147 vm_page_wakeup(fs->m);
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148 fs->m = NULL;
149}
150
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151/*
152 * The caller must hold vm_token.
153 */
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154static __inline void
155unlock_map(struct faultstate *fs)
156{
aa542ad5 157 if (fs->lookup_still_valid && fs->map) {
a108bf71 158 vm_map_lookup_done(fs->map, fs->entry, 0);
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159 fs->lookup_still_valid = FALSE;
160 }
161}
162
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163/*
164 * Clean up after a successful call to vm_fault_object() so another call
165 * to vm_fault_object() can be made.
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166 *
167 * The caller must hold vm_token.
75f59a66 168 */
984263bc 169static void
75f59a66 170_cleanup_successful_fault(struct faultstate *fs, int relock)
984263bc 171{
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172 if (fs->object != fs->first_object) {
173 vm_page_free(fs->first_m);
75f59a66 174 vm_object_pip_wakeup(fs->object);
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175 fs->first_m = NULL;
176 }
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177 fs->object = fs->first_object;
178 if (relock && fs->lookup_still_valid == FALSE) {
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179 if (fs->map)
180 vm_map_lock_read(fs->map);
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181 fs->lookup_still_valid = TRUE;
182 }
183}
184
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185/*
186 * The caller must hold vm_token.
187 */
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188static void
189_unlock_things(struct faultstate *fs, int dealloc)
190{
191 vm_object_pip_wakeup(fs->first_object);
192 _cleanup_successful_fault(fs, 0);
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193 if (dealloc) {
194 vm_object_deallocate(fs->first_object);
bc823b32 195 fs->first_object = NULL;
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196 }
197 unlock_map(fs);
198 if (fs->vp != NULL) {
199 vput(fs->vp);
200 fs->vp = NULL;
201 }
202}
203
204#define unlock_things(fs) _unlock_things(fs, 0)
205#define unlock_and_deallocate(fs) _unlock_things(fs, 1)
75f59a66 206#define cleanup_successful_fault(fs) _cleanup_successful_fault(fs, 1)
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207
208/*
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209 * TRYPAGER
210 *
211 * Determine if the pager for the current object *might* contain the page.
984263bc 212 *
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213 * We only need to try the pager if this is not a default object (default
214 * objects are zero-fill and have no real pager), and if we are not taking
215 * a wiring fault or if the FS entry is wired.
984263bc 216 */
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217#define TRYPAGER(fs) \
218 (fs->object->type != OBJT_DEFAULT && \
219 (((fs->fault_flags & VM_FAULT_WIRE_MASK) == 0) || fs->wired))
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220
221/*
568e6804 222 * vm_fault:
984263bc 223 *
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224 * Handle a page fault occuring at the given address, requiring the given
225 * permissions, in the map specified. If successful, the page is inserted
226 * into the associated physical map.
984263bc 227 *
568e6804 228 * NOTE: The given address should be truncated to the proper page address.
984263bc 229 *
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230 * KERN_SUCCESS is returned if the page fault is handled; otherwise,
231 * a standard error specifying why the fault is fatal is returned.
984263bc 232 *
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233 * The map in question must be referenced, and remains so.
234 * The caller may hold no locks.
9ad0147b 235 * No other requirements.
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236 */
237int
238vm_fault(vm_map_t map, vm_offset_t vaddr, vm_prot_t fault_type, int fault_flags)
239{
984263bc 240 int result;
72579d2e 241 vm_pindex_t first_pindex;
984263bc 242 struct faultstate fs;
8d496bf9 243 int growstack;
984263bc 244
12e4aaff 245 mycpu->gd_cnt.v_vm_faults++;
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246
247 fs.didlimit = 0;
248 fs.hardfault = 0;
249 fs.fault_flags = fault_flags;
8d496bf9 250 growstack = 1;
984263bc 251
06ecca5a 252RetryFault:
984263bc 253 /*
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254 * Find the vm_map_entry representing the backing store and resolve
255 * the top level object and page index. This may have the side
256 * effect of executing a copy-on-write on the map entry and/or
257 * creating a shadow object, but will not COW any actual VM pages.
258 *
259 * On success fs.map is left read-locked and various other fields
260 * are initialized but not otherwise referenced or locked.
261 *
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262 * NOTE! vm_map_lookup will try to upgrade the fault_type to
263 * VM_FAULT_WRITE if the map entry is a virtual page table and also
264 * writable, so we can set the 'A'accessed bit in the virtual page
265 * table entry.
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266 */
267 fs.map = map;
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268 result = vm_map_lookup(&fs.map, vaddr, fault_type,
269 &fs.entry, &fs.first_object,
72579d2e 270 &first_pindex, &fs.first_prot, &fs.wired);
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271
272 /*
273 * If the lookup failed or the map protections are incompatible,
274 * the fault generally fails. However, if the caller is trying
275 * to do a user wiring we have more work to do.
276 */
277 if (result != KERN_SUCCESS) {
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278 if (result != KERN_PROTECTION_FAILURE ||
279 (fs.fault_flags & VM_FAULT_WIRE_MASK) != VM_FAULT_USER_WIRE)
280 {
281 if (result == KERN_INVALID_ADDRESS && growstack &&
282 map != &kernel_map && curproc != NULL) {
283 result = vm_map_growstack(curproc, vaddr);
284 if (result != KERN_SUCCESS)
285 return (KERN_FAILURE);
286 growstack = 0;
287 goto RetryFault;
288 }
289 return (result);
290 }
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291
292 /*
293 * If we are user-wiring a r/w segment, and it is COW, then
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294 * we need to do the COW operation. Note that we don't
295 * currently COW RO sections now, because it is NOT desirable
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296 * to COW .text. We simply keep .text from ever being COW'ed
297 * and take the heat that one cannot debug wired .text sections.
298 */
299 result = vm_map_lookup(&fs.map, vaddr,
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300 VM_PROT_READ|VM_PROT_WRITE|
301 VM_PROT_OVERRIDE_WRITE,
302 &fs.entry, &fs.first_object,
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303 &first_pindex, &fs.first_prot,
304 &fs.wired);
568e6804 305 if (result != KERN_SUCCESS)
984263bc 306 return result;
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307
308 /*
309 * If we don't COW now, on a user wire, the user will never
310 * be able to write to the mapping. If we don't make this
311 * restriction, the bookkeeping would be nearly impossible.
312 */
313 if ((fs.entry->protection & VM_PROT_WRITE) == 0)
314 fs.entry->max_protection &= ~VM_PROT_WRITE;
315 }
316
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317 /*
318 * fs.map is read-locked
319 *
320 * Misc checks. Save the map generation number to detect races.
321 */
322 fs.map_generation = fs.map->timestamp;
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323
324 if (fs.entry->eflags & MAP_ENTRY_NOFAULT) {
325 panic("vm_fault: fault on nofault entry, addr: %lx",
326 (u_long)vaddr);
327 }
328
329 /*
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330 * A system map entry may return a NULL object. No object means
331 * no pager means an unrecoverable kernel fault.
332 */
333 if (fs.first_object == NULL) {
334 panic("vm_fault: unrecoverable fault at %p in entry %p",
335 (void *)vaddr, fs.entry);
336 }
337
338 /*
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339 * Make a reference to this object to prevent its disposal while we
340 * are messing with it. Once we have the reference, the map is free
341 * to be diddled. Since objects reference their shadows (and copies),
342 * they will stay around as well.
343 *
344 * Bump the paging-in-progress count to prevent size changes (e.g.
345 * truncation operations) during I/O. This must be done after
346 * obtaining the vnode lock in order to avoid possible deadlocks.
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347 *
348 * The vm_token is needed to manipulate the vm_object
984263bc 349 */
9ad0147b 350 lwkt_gettoken(&vm_token);
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351 vm_object_reference(fs.first_object);
352 fs.vp = vnode_pager_lock(fs.first_object);
353 vm_object_pip_add(fs.first_object, 1);
9ad0147b 354 lwkt_reltoken(&vm_token);
984263bc 355
984263bc 356 fs.lookup_still_valid = TRUE;
984263bc 357 fs.first_m = NULL;
afeabdca 358 fs.object = fs.first_object; /* so unlock_and_deallocate works */
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359
360 /*
568e6804 361 * If the entry is wired we cannot change the page protection.
984263bc 362 */
568e6804 363 if (fs.wired)
72579d2e 364 fault_type = fs.first_prot;
984263bc 365
568e6804 366 /*
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367 * The page we want is at (first_object, first_pindex), but if the
368 * vm_map_entry is VM_MAPTYPE_VPAGETABLE we have to traverse the
369 * page table to figure out the actual pindex.
370 *
371 * NOTE! DEVELOPMENT IN PROGRESS, THIS IS AN INITIAL IMPLEMENTATION
372 * ONLY
568e6804 373 */
568e6804 374 if (fs.entry->maptype == VM_MAPTYPE_VPAGETABLE) {
72579d2e 375 result = vm_fault_vpagetable(&fs, &first_pindex,
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376 fs.entry->aux.master_pde,
377 fault_type);
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378 if (result == KERN_TRY_AGAIN)
379 goto RetryFault;
75f59a66 380 if (result != KERN_SUCCESS)
568e6804 381 return (result);
568e6804 382 }
75f59a66 383
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384 /*
385 * Now we have the actual (object, pindex), fault in the page. If
386 * vm_fault_object() fails it will unlock and deallocate the FS
75f59a66 387 * data. If it succeeds everything remains locked and fs->object
9ad0147b 388 * will have an additional PIP count if it is not equal to
75f59a66 389 * fs->first_object
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390 *
391 * vm_fault_object will set fs->prot for the pmap operation. It is
392 * allowed to set VM_PROT_WRITE if fault_type == VM_PROT_READ if the
393 * page can be safely written. However, it will force a read-only
394 * mapping for a read fault if the memory is managed by a virtual
395 * page table.
568e6804 396 */
72579d2e 397 result = vm_fault_object(&fs, first_pindex, fault_type);
afeabdca 398
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399 if (result == KERN_TRY_AGAIN)
400 goto RetryFault;
401 if (result != KERN_SUCCESS)
402 return (result);
403
404 /*
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405 * On success vm_fault_object() does not unlock or deallocate, and fs.m
406 * will contain a busied page.
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407 *
408 * Enter the page into the pmap and do pmap-related adjustments.
409 */
410 pmap_enter(fs.map->pmap, vaddr, fs.m, fs.prot, fs.wired);
411
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412 /*
413 * Burst in a few more pages if possible. The fs.map should still
414 * be locked.
415 */
416 if (fault_flags & VM_FAULT_BURST) {
417 if ((fs.fault_flags & VM_FAULT_WIRE_MASK) == 0 &&
418 fs.wired == 0) {
419 vm_prefault(fs.map->pmap, vaddr, fs.entry, fs.prot);
420 }
568e6804 421 }
1b9d3514 422 unlock_things(&fs);
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423
424 vm_page_flag_clear(fs.m, PG_ZERO);
17cde63e 425 vm_page_flag_set(fs.m, PG_REFERENCED);
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426
427 /*
428 * If the page is not wired down, then put it where the pageout daemon
429 * can find it.
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430 *
431 * We do not really need to get vm_token here but since all the
432 * vm_*() calls have to doing it here improves efficiency.
568e6804 433 */
9ad0147b 434 lwkt_gettoken(&vm_token);
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435 if (fs.fault_flags & VM_FAULT_WIRE_MASK) {
436 if (fs.wired)
437 vm_page_wire(fs.m);
438 else
439 vm_page_unwire(fs.m, 1);
440 } else {
441 vm_page_activate(fs.m);
442 }
443
fde7ac71 444 if (curthread->td_lwp) {
568e6804 445 if (fs.hardfault) {
fde7ac71 446 curthread->td_lwp->lwp_ru.ru_majflt++;
568e6804 447 } else {
fde7ac71 448 curthread->td_lwp->lwp_ru.ru_minflt++;
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449 }
450 }
451
452 /*
453 * Unlock everything, and return
454 */
455 vm_page_wakeup(fs.m);
456 vm_object_deallocate(fs.first_object);
9ad0147b 457 lwkt_reltoken(&vm_token);
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458
459 return (KERN_SUCCESS);
460}
461
462/*
5a0e2a66
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463 * Fault in the specified virtual address in the current process map,
464 * returning a held VM page or NULL. See vm_fault_page() for more
465 * information.
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466 *
467 * No requirements.
5a0e2a66
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468 */
469vm_page_t
470vm_fault_page_quick(vm_offset_t va, vm_prot_t fault_type, int *errorp)
471{
287ebb09 472 struct lwp *lp = curthread->td_lwp;
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473 vm_page_t m;
474
287ebb09 475 m = vm_fault_page(&lp->lwp_vmspace->vm_map, va,
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476 fault_type, VM_FAULT_NORMAL, errorp);
477 return(m);
478}
479
480/*
481 * Fault in the specified virtual address in the specified map, doing all
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482 * necessary manipulation of the object store and all necessary I/O. Return
483 * a held VM page or NULL, and set *errorp. The related pmap is not
484 * updated.
485 *
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486 * The returned page will be properly dirtied if VM_PROT_WRITE was specified,
487 * and marked PG_REFERENCED as well.
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488 *
489 * If the page cannot be faulted writable and VM_PROT_WRITE was specified, an
490 * error will be returned.
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491 *
492 * No requirements.
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493 */
494vm_page_t
495vm_fault_page(vm_map_t map, vm_offset_t vaddr, vm_prot_t fault_type,
496 int fault_flags, int *errorp)
497{
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498 vm_pindex_t first_pindex;
499 struct faultstate fs;
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500 int result;
501 vm_prot_t orig_fault_type = fault_type;
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502
503 mycpu->gd_cnt.v_vm_faults++;
504
505 fs.didlimit = 0;
506 fs.hardfault = 0;
507 fs.fault_flags = fault_flags;
508 KKASSERT((fault_flags & VM_FAULT_WIRE_MASK) == 0);
509
510RetryFault:
511 /*
512 * Find the vm_map_entry representing the backing store and resolve
513 * the top level object and page index. This may have the side
514 * effect of executing a copy-on-write on the map entry and/or
515 * creating a shadow object, but will not COW any actual VM pages.
516 *
517 * On success fs.map is left read-locked and various other fields
518 * are initialized but not otherwise referenced or locked.
519 *
520 * NOTE! vm_map_lookup will upgrade the fault_type to VM_FAULT_WRITE
521 * if the map entry is a virtual page table and also writable,
522 * so we can set the 'A'accessed bit in the virtual page table entry.
523 */
524 fs.map = map;
525 result = vm_map_lookup(&fs.map, vaddr, fault_type,
526 &fs.entry, &fs.first_object,
527 &first_pindex, &fs.first_prot, &fs.wired);
528
529 if (result != KERN_SUCCESS) {
530 *errorp = result;
531 return (NULL);
532 }
533
534 /*
535 * fs.map is read-locked
536 *
537 * Misc checks. Save the map generation number to detect races.
538 */
539 fs.map_generation = fs.map->timestamp;
540
541 if (fs.entry->eflags & MAP_ENTRY_NOFAULT) {
542 panic("vm_fault: fault on nofault entry, addr: %lx",
543 (u_long)vaddr);
544 }
545
546 /*
547 * A system map entry may return a NULL object. No object means
548 * no pager means an unrecoverable kernel fault.
549 */
550 if (fs.first_object == NULL) {
551 panic("vm_fault: unrecoverable fault at %p in entry %p",
552 (void *)vaddr, fs.entry);
553 }
554
555 /*
556 * Make a reference to this object to prevent its disposal while we
557 * are messing with it. Once we have the reference, the map is free
558 * to be diddled. Since objects reference their shadows (and copies),
559 * they will stay around as well.
560 *
561 * Bump the paging-in-progress count to prevent size changes (e.g.
562 * truncation operations) during I/O. This must be done after
563 * obtaining the vnode lock in order to avoid possible deadlocks.
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564 *
565 * The vm_token is needed to manipulate the vm_object
4e158347 566 */
9ad0147b 567 lwkt_gettoken(&vm_token);
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568 vm_object_reference(fs.first_object);
569 fs.vp = vnode_pager_lock(fs.first_object);
570 vm_object_pip_add(fs.first_object, 1);
9ad0147b 571 lwkt_reltoken(&vm_token);
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572
573 fs.lookup_still_valid = TRUE;
574 fs.first_m = NULL;
575 fs.object = fs.first_object; /* so unlock_and_deallocate works */
576
577 /*
578 * If the entry is wired we cannot change the page protection.
579 */
580 if (fs.wired)
581 fault_type = fs.first_prot;
582
583 /*
584 * The page we want is at (first_object, first_pindex), but if the
585 * vm_map_entry is VM_MAPTYPE_VPAGETABLE we have to traverse the
586 * page table to figure out the actual pindex.
587 *
588 * NOTE! DEVELOPMENT IN PROGRESS, THIS IS AN INITIAL IMPLEMENTATION
589 * ONLY
590 */
591 if (fs.entry->maptype == VM_MAPTYPE_VPAGETABLE) {
592 result = vm_fault_vpagetable(&fs, &first_pindex,
4e7c41c5
MD
593 fs.entry->aux.master_pde,
594 fault_type);
4e158347
MD
595 if (result == KERN_TRY_AGAIN)
596 goto RetryFault;
597 if (result != KERN_SUCCESS) {
598 *errorp = result;
599 return (NULL);
600 }
601 }
602
603 /*
604 * Now we have the actual (object, pindex), fault in the page. If
605 * vm_fault_object() fails it will unlock and deallocate the FS
606 * data. If it succeeds everything remains locked and fs->object
607 * will have an additinal PIP count if it is not equal to
608 * fs->first_object
609 */
610 result = vm_fault_object(&fs, first_pindex, fault_type);
611
612 if (result == KERN_TRY_AGAIN)
613 goto RetryFault;
614 if (result != KERN_SUCCESS) {
615 *errorp = result;
616 return(NULL);
617 }
618
17cde63e
MD
619 if ((orig_fault_type & VM_PROT_WRITE) &&
620 (fs.prot & VM_PROT_WRITE) == 0) {
621 *errorp = KERN_PROTECTION_FAILURE;
622 unlock_and_deallocate(&fs);
623 return(NULL);
624 }
625
4e158347
MD
626 /*
627 * On success vm_fault_object() does not unlock or deallocate, and fs.m
628 * will contain a busied page.
629 */
630 unlock_things(&fs);
631
632 /*
633 * Return a held page. We are not doing any pmap manipulation so do
5a0e2a66
MD
634 * not set PG_MAPPED. However, adjust the page flags according to
635 * the fault type because the caller may not use a managed pmapping
636 * (so we don't want to lose the fact that the page will be dirtied
637 * if a write fault was specified).
4e158347 638 */
573fb415 639 lwkt_gettoken(&vm_token);
5a0e2a66 640 vm_page_hold(fs.m);
4e158347 641 vm_page_flag_clear(fs.m, PG_ZERO);
5a0e2a66
MD
642 if (fault_type & VM_PROT_WRITE)
643 vm_page_dirty(fs.m);
4e158347
MD
644
645 /*
40d6ef3a
MD
646 * Update the pmap. We really only have to do this if a COW
647 * occured to replace the read-only page with the new page. For
648 * now just do it unconditionally. XXX
649 */
650 pmap_enter(fs.map->pmap, vaddr, fs.m, fs.prot, fs.wired);
17cde63e 651 vm_page_flag_set(fs.m, PG_REFERENCED);
40d6ef3a
MD
652
653 /*
4e158347
MD
654 * Unbusy the page by activating it. It remains held and will not
655 * be reclaimed.
656 */
657 vm_page_activate(fs.m);
658
659 if (curthread->td_lwp) {
660 if (fs.hardfault) {
661 curthread->td_lwp->lwp_ru.ru_majflt++;
662 } else {
663 curthread->td_lwp->lwp_ru.ru_minflt++;
664 }
665 }
666
667 /*
668 * Unlock everything, and return the held page.
669 */
670 vm_page_wakeup(fs.m);
671 vm_object_deallocate(fs.first_object);
9ad0147b 672 lwkt_reltoken(&vm_token);
4e158347
MD
673
674 *errorp = 0;
675 return(fs.m);
676}
677
678/*
17cde63e
MD
679 * Fault in the specified (object,offset), dirty the returned page as
680 * needed. If the requested fault_type cannot be done NULL and an
681 * error is returned.
9ad0147b
MD
682 *
683 * A held (but not busied) page is returned.
684 *
685 * No requirements.
aa542ad5
MD
686 */
687vm_page_t
688vm_fault_object_page(vm_object_t object, vm_ooffset_t offset,
689 vm_prot_t fault_type, int fault_flags, int *errorp)
690{
691 int result;
692 vm_pindex_t first_pindex;
693 struct faultstate fs;
694 struct vm_map_entry entry;
695
696 bzero(&entry, sizeof(entry));
697 entry.object.vm_object = object;
698 entry.maptype = VM_MAPTYPE_NORMAL;
699 entry.protection = entry.max_protection = fault_type;
700
701 fs.didlimit = 0;
702 fs.hardfault = 0;
703 fs.fault_flags = fault_flags;
704 fs.map = NULL;
705 KKASSERT((fault_flags & VM_FAULT_WIRE_MASK) == 0);
706
707RetryFault:
708
709 fs.first_object = object;
710 first_pindex = OFF_TO_IDX(offset);
711 fs.entry = &entry;
712 fs.first_prot = fault_type;
713 fs.wired = 0;
714 /*fs.map_generation = 0; unused */
715
716 /*
717 * Make a reference to this object to prevent its disposal while we
718 * are messing with it. Once we have the reference, the map is free
719 * to be diddled. Since objects reference their shadows (and copies),
720 * they will stay around as well.
721 *
722 * Bump the paging-in-progress count to prevent size changes (e.g.
723 * truncation operations) during I/O. This must be done after
724 * obtaining the vnode lock in order to avoid possible deadlocks.
725 */
9ad0147b 726 lwkt_gettoken(&vm_token);
aa542ad5
MD
727 vm_object_reference(fs.first_object);
728 fs.vp = vnode_pager_lock(fs.first_object);
729 vm_object_pip_add(fs.first_object, 1);
9ad0147b 730 lwkt_reltoken(&vm_token);
aa542ad5
MD
731
732 fs.lookup_still_valid = TRUE;
733 fs.first_m = NULL;
734 fs.object = fs.first_object; /* so unlock_and_deallocate works */
735
736#if 0
737 /* XXX future - ability to operate on VM object using vpagetable */
738 if (fs.entry->maptype == VM_MAPTYPE_VPAGETABLE) {
739 result = vm_fault_vpagetable(&fs, &first_pindex,
740 fs.entry->aux.master_pde,
741 fault_type);
742 if (result == KERN_TRY_AGAIN)
743 goto RetryFault;
744 if (result != KERN_SUCCESS) {
745 *errorp = result;
746 return (NULL);
747 }
748 }
749#endif
750
751 /*
752 * Now we have the actual (object, pindex), fault in the page. If
753 * vm_fault_object() fails it will unlock and deallocate the FS
754 * data. If it succeeds everything remains locked and fs->object
755 * will have an additinal PIP count if it is not equal to
756 * fs->first_object
757 */
758 result = vm_fault_object(&fs, first_pindex, fault_type);
759
760 if (result == KERN_TRY_AGAIN)
761 goto RetryFault;
762 if (result != KERN_SUCCESS) {
763 *errorp = result;
764 return(NULL);
765 }
766
17cde63e
MD
767 if ((fault_type & VM_PROT_WRITE) && (fs.prot & VM_PROT_WRITE) == 0) {
768 *errorp = KERN_PROTECTION_FAILURE;
769 unlock_and_deallocate(&fs);
770 return(NULL);
771 }
772
aa542ad5
MD
773 /*
774 * On success vm_fault_object() does not unlock or deallocate, and fs.m
775 * will contain a busied page.
776 */
777 unlock_things(&fs);
778
779 /*
780 * Return a held page. We are not doing any pmap manipulation so do
781 * not set PG_MAPPED. However, adjust the page flags according to
782 * the fault type because the caller may not use a managed pmapping
783 * (so we don't want to lose the fact that the page will be dirtied
784 * if a write fault was specified).
785 */
9ad0147b 786 lwkt_gettoken(&vm_token);
aa542ad5
MD
787 vm_page_hold(fs.m);
788 vm_page_flag_clear(fs.m, PG_ZERO);
789 if (fault_type & VM_PROT_WRITE)
790 vm_page_dirty(fs.m);
791
792 /*
793 * Indicate that the page was accessed.
794 */
795 vm_page_flag_set(fs.m, PG_REFERENCED);
796
797 /*
798 * Unbusy the page by activating it. It remains held and will not
799 * be reclaimed.
800 */
801 vm_page_activate(fs.m);
802
803 if (curthread->td_lwp) {
804 if (fs.hardfault) {
805 mycpu->gd_cnt.v_vm_faults++;
806 curthread->td_lwp->lwp_ru.ru_majflt++;
807 } else {
808 curthread->td_lwp->lwp_ru.ru_minflt++;
809 }
810 }
811
812 /*
813 * Unlock everything, and return the held page.
814 */
815 vm_page_wakeup(fs.m);
816 vm_object_deallocate(fs.first_object);
9ad0147b 817 lwkt_reltoken(&vm_token);
aa542ad5
MD
818
819 *errorp = 0;
820 return(fs.m);
821}
822
823/*
72579d2e 824 * Translate the virtual page number (first_pindex) that is relative
afeabdca
MD
825 * to the address space into a logical page number that is relative to the
826 * backing object. Use the virtual page table pointed to by (vpte).
827 *
828 * This implements an N-level page table. Any level can terminate the
829 * scan by setting VPTE_PS. A linear mapping is accomplished by setting
830 * VPTE_PS in the master page directory entry set via mcontrol(MADV_SETMAP).
9ad0147b
MD
831 *
832 * No requirements (vm_token need not be held).
afeabdca
MD
833 */
834static
835int
4e7c41c5
MD
836vm_fault_vpagetable(struct faultstate *fs, vm_pindex_t *pindex,
837 vpte_t vpte, int fault_type)
afeabdca 838{
5c5185ae 839 struct lwbuf *lwb;
8608b858 840 int vshift = VPTE_FRAME_END - PAGE_SHIFT; /* index bits remaining */
72579d2e 841 int result = KERN_SUCCESS;
4e7c41c5 842 vpte_t *ptep;
afeabdca
MD
843
844 for (;;) {
4e7c41c5
MD
845 /*
846 * We cannot proceed if the vpte is not valid, not readable
847 * for a read fault, or not writable for a write fault.
848 */
afeabdca
MD
849 if ((vpte & VPTE_V) == 0) {
850 unlock_and_deallocate(fs);
851 return (KERN_FAILURE);
852 }
4e7c41c5
MD
853 if ((fault_type & VM_PROT_READ) && (vpte & VPTE_R) == 0) {
854 unlock_and_deallocate(fs);
855 return (KERN_FAILURE);
856 }
857 if ((fault_type & VM_PROT_WRITE) && (vpte & VPTE_W) == 0) {
858 unlock_and_deallocate(fs);
859 return (KERN_FAILURE);
860 }
afeabdca
MD
861 if ((vpte & VPTE_PS) || vshift == 0)
862 break;
863 KKASSERT(vshift >= VPTE_PAGE_BITS);
864
865 /*
4e7c41c5
MD
866 * Get the page table page. Nominally we only read the page
867 * table, but since we are actively setting VPTE_M and VPTE_A,
868 * tell vm_fault_object() that we are writing it.
869 *
870 * There is currently no real need to optimize this.
afeabdca 871 */
61cddc1c 872 result = vm_fault_object(fs, (vpte & VPTE_FRAME) >> PAGE_SHIFT,
0035dca9 873 VM_PROT_READ|VM_PROT_WRITE);
afeabdca
MD
874 if (result != KERN_SUCCESS)
875 return (result);
876
877 /*
878 * Process the returned fs.m and look up the page table
879 * entry in the page table page.
880 */
881 vshift -= VPTE_PAGE_BITS;
5c5185ae
SG
882 lwb = lwbuf_alloc(fs->m);
883 ptep = ((vpte_t *)lwbuf_kva(lwb) +
4e7c41c5
MD
884 ((*pindex >> vshift) & VPTE_PAGE_MASK));
885 vpte = *ptep;
886
887 /*
888 * Page table write-back. If the vpte is valid for the
889 * requested operation, do a write-back to the page table.
890 *
891 * XXX VPTE_M is not set properly for page directory pages.
892 * It doesn't get set in the page directory if the page table
893 * is modified during a read access.
894 */
895 if ((fault_type & VM_PROT_WRITE) && (vpte & VPTE_V) &&
896 (vpte & VPTE_W)) {
0035dca9 897 if ((vpte & (VPTE_M|VPTE_A)) != (VPTE_M|VPTE_A)) {
8608b858 898 atomic_set_long(ptep, VPTE_M | VPTE_A);
4e7c41c5
MD
899 vm_page_dirty(fs->m);
900 }
901 }
902 if ((fault_type & VM_PROT_READ) && (vpte & VPTE_V) &&
903 (vpte & VPTE_R)) {
904 if ((vpte & VPTE_A) == 0) {
61cddc1c 905 atomic_set_long(ptep, VPTE_A);
4e7c41c5
MD
906 vm_page_dirty(fs->m);
907 }
908 }
5c5185ae 909 lwbuf_free(lwb);
afeabdca
MD
910 vm_page_flag_set(fs->m, PG_REFERENCED);
911 vm_page_activate(fs->m);
912 vm_page_wakeup(fs->m);
913 cleanup_successful_fault(fs);
914 }
afeabdca
MD
915 /*
916 * Combine remaining address bits with the vpte.
917 */
61cddc1c
JG
918 /* JG how many bits from each? */
919 *pindex = ((vpte & VPTE_FRAME) >> PAGE_SHIFT) +
920 (*pindex & ((1L << vshift) - 1));
afeabdca
MD
921 return (KERN_SUCCESS);
922}
923
924
925/*
9ad0147b
MD
926 * This is the core of the vm_fault code.
927 *
72579d2e 928 * Do all operations required to fault-in (fs.first_object, pindex). Run
568e6804
MD
929 * through the shadow chain as necessary and do required COW or virtual
930 * copy operations. The caller has already fully resolved the vm_map_entry
931 * and, if appropriate, has created a copy-on-write layer. All we need to
932 * do is iterate the object chain.
933 *
934 * On failure (fs) is unlocked and deallocated and the caller may return or
75f59a66
MD
935 * retry depending on the failure code. On success (fs) is NOT unlocked or
936 * deallocated, fs.m will contained a resolved, busied page, and fs.object
937 * will have an additional PIP count if it is not equal to fs.first_object.
9ad0147b
MD
938 *
939 * No requirements.
568e6804
MD
940 */
941static
942int
72579d2e
MD
943vm_fault_object(struct faultstate *fs,
944 vm_pindex_t first_pindex, vm_prot_t fault_type)
568e6804
MD
945{
946 vm_object_t next_object;
72579d2e 947 vm_pindex_t pindex;
568e6804 948
72579d2e
MD
949 fs->prot = fs->first_prot;
950 fs->object = fs->first_object;
951 pindex = first_pindex;
952
4e7c41c5
MD
953 /*
954 * If a read fault occurs we try to make the page writable if
955 * possible. There are three cases where we cannot make the
956 * page mapping writable:
957 *
958 * (1) The mapping is read-only or the VM object is read-only,
0035dca9 959 * fs->prot above will simply not have VM_PROT_WRITE set.
4e7c41c5
MD
960 *
961 * (2) If the mapping is a virtual page table we need to be able
70fc5283
MD
962 * to detect writes so we can set VPTE_M in the virtual page
963 * table.
4e7c41c5
MD
964 *
965 * (3) If the VM page is read-only or copy-on-write, upgrading would
966 * just result in an unnecessary COW fault.
0035dca9
MD
967 *
968 * VM_PROT_VPAGED is set if faulting via a virtual page table and
969 * causes adjustments to the 'M'odify bit to also turn off write
970 * access to force a re-fault.
4e7c41c5 971 */
0035dca9
MD
972 if (fs->entry->maptype == VM_MAPTYPE_VPAGETABLE) {
973 if ((fault_type & VM_PROT_WRITE) == 0)
974 fs->prot &= ~VM_PROT_WRITE;
4e7c41c5
MD
975 }
976
9ad0147b
MD
977 lwkt_gettoken(&vm_token);
978
568e6804
MD
979 for (;;) {
980 /*
981 * If the object is dead, we stop here
982 */
983 if (fs->object->flags & OBJ_DEAD) {
984 unlock_and_deallocate(fs);
9ad0147b 985 lwkt_reltoken(&vm_token);
984263bc
MD
986 return (KERN_PROTECTION_FAILURE);
987 }
988
989 /*
06ecca5a
MD
990 * See if page is resident. spl protection is required
991 * to avoid an interrupt unbusy/free race against our
992 * lookup. We must hold the protection through a page
993 * allocation or busy.
984263bc 994 */
654a39f0 995 crit_enter();
72579d2e 996 fs->m = vm_page_lookup(fs->object, pindex);
568e6804 997 if (fs->m != NULL) {
06ecca5a 998 int queue;
984263bc
MD
999 /*
1000 * Wait/Retry if the page is busy. We have to do this
1001 * if the page is busy via either PG_BUSY or
1002 * vm_page_t->busy because the vm_pager may be using
1003 * vm_page_t->busy for pageouts ( and even pageins if
1004 * it is the vnode pager ), and we could end up trying
1005 * to pagein and pageout the same page simultaneously.
1006 *
1007 * We can theoretically allow the busy case on a read
1008 * fault if the page is marked valid, but since such
1009 * pages are typically already pmap'd, putting that
1010 * special case in might be more effort then it is
1011 * worth. We cannot under any circumstances mess
1012 * around with a vm_page_t->busy page except, perhaps,
1013 * to pmap it.
1014 */
568e6804
MD
1015 if ((fs->m->flags & PG_BUSY) || fs->m->busy) {
1016 unlock_things(fs);
1017 vm_page_sleep_busy(fs->m, TRUE, "vmpfw");
12e4aaff 1018 mycpu->gd_cnt.v_intrans++;
568e6804 1019 vm_object_deallocate(fs->first_object);
bc823b32 1020 fs->first_object = NULL;
9ad0147b 1021 lwkt_reltoken(&vm_token);
654a39f0 1022 crit_exit();
568e6804 1023 return (KERN_TRY_AGAIN);
984263bc
MD
1024 }
1025
568e6804
MD
1026 /*
1027 * If reactivating a page from PQ_CACHE we may have
1028 * to rate-limit.
1029 */
1030 queue = fs->m->queue;
1031 vm_page_unqueue_nowakeup(fs->m);
984263bc 1032
568e6804
MD
1033 if ((queue - fs->m->pc) == PQ_CACHE &&
1034 vm_page_count_severe()) {
1035 vm_page_activate(fs->m);
1036 unlock_and_deallocate(fs);
659c6a07 1037 vm_waitpfault();
9ad0147b 1038 lwkt_reltoken(&vm_token);
654a39f0 1039 crit_exit();
568e6804 1040 return (KERN_TRY_AGAIN);
984263bc
MD
1041 }
1042
1043 /*
1044 * Mark page busy for other processes, and the
1045 * pagedaemon. If it still isn't completely valid
cf1bb2a8
MD
1046 * (readable), or if a read-ahead-mark is set on
1047 * the VM page, jump to readrest, else we found the
568e6804 1048 * page and can return.
06ecca5a
MD
1049 *
1050 * We can release the spl once we have marked the
1051 * page busy.
984263bc 1052 */
568e6804 1053 vm_page_busy(fs->m);
654a39f0 1054 crit_exit();
06ecca5a 1055
cf1bb2a8
MD
1056 if (fs->m->object != &kernel_object) {
1057 if ((fs->m->valid & VM_PAGE_BITS_ALL) !=
1058 VM_PAGE_BITS_ALL) {
1059 goto readrest;
1060 }
1061 if (fs->m->flags & PG_RAM) {
1062 if (debug_cluster)
1063 kprintf("R");
1064 vm_page_flag_clear(fs->m, PG_RAM);
1065 goto readrest;
1066 }
984263bc 1067 }
568e6804 1068 break; /* break to PAGE HAS BEEN FOUND */
984263bc
MD
1069 }
1070
1071 /*
1072 * Page is not resident, If this is the search termination
1073 * or the pager might contain the page, allocate a new page.
06ecca5a 1074 *
568e6804 1075 * NOTE: We are still in a critical section.
984263bc 1076 */
568e6804
MD
1077 if (TRYPAGER(fs) || fs->object == fs->first_object) {
1078 /*
1079 * If the page is beyond the object size we fail
1080 */
72579d2e 1081 if (pindex >= fs->object->size) {
9ad0147b 1082 lwkt_reltoken(&vm_token);
654a39f0 1083 crit_exit();
568e6804 1084 unlock_and_deallocate(fs);
984263bc
MD
1085 return (KERN_PROTECTION_FAILURE);
1086 }
1087
1088 /*
46311ac2
MD
1089 * Ratelimit.
1090 */
568e6804
MD
1091 if (fs->didlimit == 0 && curproc != NULL) {
1092 int limticks;
1093
1094 limticks = vm_fault_ratelimit(curproc->p_vmspace);
46311ac2 1095 if (limticks) {
9ad0147b 1096 lwkt_reltoken(&vm_token);
46311ac2 1097 crit_exit();
568e6804 1098 unlock_and_deallocate(fs);
46311ac2 1099 tsleep(curproc, 0, "vmrate", limticks);
568e6804
MD
1100 fs->didlimit = 1;
1101 return (KERN_TRY_AGAIN);
46311ac2
MD
1102 }
1103 }
1104
1105 /*
984263bc
MD
1106 * Allocate a new page for this object/offset pair.
1107 */
568e6804 1108 fs->m = NULL;
984263bc 1109 if (!vm_page_count_severe()) {
72579d2e 1110 fs->m = vm_page_alloc(fs->object, pindex,
568e6804 1111 (fs->vp || fs->object->backing_object) ? VM_ALLOC_NORMAL : VM_ALLOC_NORMAL | VM_ALLOC_ZERO);
984263bc 1112 }
568e6804 1113 if (fs->m == NULL) {
9ad0147b 1114 lwkt_reltoken(&vm_token);
654a39f0 1115 crit_exit();
568e6804 1116 unlock_and_deallocate(fs);
659c6a07 1117 vm_waitpfault();
568e6804 1118 return (KERN_TRY_AGAIN);
984263bc
MD
1119 }
1120 }
654a39f0 1121 crit_exit();
984263bc
MD
1122
1123readrest:
1124 /*
1b9d3514 1125 * We have found an invalid or partially valid page, a
1c9602b3
MD
1126 * page with a read-ahead mark which might be partially or
1127 * fully valid (and maybe dirty too), or we have allocated
1128 * a new page.
984263bc
MD
1129 *
1130 * Attempt to fault-in the page if there is a chance that the
1131 * pager has it, and potentially fault in additional pages
1132 * at the same time.
06ecca5a
MD
1133 *
1134 * We are NOT in splvm here and if TRYPAGER is true then
1135 * fs.m will be non-NULL and will be PG_BUSY for us.
984263bc 1136 */
568e6804 1137 if (TRYPAGER(fs)) {
984263bc 1138 int rv;
1b9d3514 1139 int seqaccess;
568e6804 1140 u_char behavior = vm_map_entry_behavior(fs->entry);
984263bc 1141
1b9d3514
MD
1142 if (behavior == MAP_ENTRY_BEHAV_RANDOM)
1143 seqaccess = 0;
1144 else
1145 seqaccess = -1;
984263bc 1146
1b9d3514
MD
1147 /*
1148 * If sequential access is detected then attempt
1149 * to deactivate/cache pages behind the scan to
1150 * prevent resource hogging.
1151 *
1152 * Use of PG_RAM to detect sequential access
1153 * also simulates multi-zone sequential access
1154 * detection for free.
1155 *
1156 * NOTE: Partially valid dirty pages cannot be
1157 * deactivated without causing NFS picemeal
1158 * writes to barf.
1159 */
568e6804 1160 if ((fs->first_object->type != OBJT_DEVICE) &&
984263bc
MD
1161 (behavior == MAP_ENTRY_BEHAV_SEQUENTIAL ||
1162 (behavior != MAP_ENTRY_BEHAV_RANDOM &&
1b9d3514 1163 (fs->m->flags & PG_RAM)))
984263bc 1164 ) {
1b9d3514
MD
1165 vm_pindex_t scan_pindex;
1166 int scan_count = 16;
1167
1168 if (first_pindex < 16) {
1169 scan_pindex = 0;
1170 scan_count = 0;
1171 } else {
1172 scan_pindex = first_pindex - 16;
1173 if (scan_pindex < 16)
1174 scan_count = scan_pindex;
1175 else
1176 scan_count = 16;
1177 }
984263bc 1178
654a39f0 1179 crit_enter();
1b9d3514 1180 while (scan_count) {
984263bc 1181 vm_page_t mt;
568e6804 1182
1b9d3514
MD
1183 mt = vm_page_lookup(fs->first_object,
1184 scan_pindex);
1185 if (mt == NULL ||
1186 (mt->valid != VM_PAGE_BITS_ALL)) {
984263bc 1187 break;
1b9d3514 1188 }
984263bc 1189 if (mt->busy ||
1b9d3514
MD
1190 (mt->flags & (PG_BUSY | PG_FICTITIOUS | PG_UNMANAGED)) ||
1191 mt->hold_count ||
1192 mt->wire_count) {
1193 goto skip;
1194 }
984263bc
MD
1195 if (mt->dirty == 0)
1196 vm_page_test_dirty(mt);
1197 if (mt->dirty) {
17cde63e 1198 vm_page_busy(mt);
1b9d3514
MD
1199 vm_page_protect(mt,
1200 VM_PROT_NONE);
984263bc 1201 vm_page_deactivate(mt);
17cde63e 1202 vm_page_wakeup(mt);
984263bc
MD
1203 } else {
1204 vm_page_cache(mt);
1205 }
1b9d3514
MD
1206skip:
1207 --scan_count;
1208 --scan_pindex;
984263bc 1209 }
654a39f0 1210 crit_exit();
984263bc 1211
1b9d3514 1212 seqaccess = 1;
984263bc
MD
1213 }
1214
1215 /*
1b9d3514
MD
1216 * Avoid deadlocking against the map when doing I/O.
1217 * fs.object and the page is PG_BUSY'd.
984263bc 1218 */
1b9d3514 1219 unlock_map(fs);
984263bc
MD
1220
1221 /*
1b9d3514
MD
1222 * Acquire the page data. We still hold a ref on
1223 * fs.object and the page has been PG_BUSY's.
1224 *
1225 * The pager may replace the page (for example, in
1226 * order to enter a fictitious page into the
1227 * object). If it does so it is responsible for
1228 * cleaning up the passed page and properly setting
1229 * the new page PG_BUSY.
1c9602b3
MD
1230 *
1231 * If we got here through a PG_RAM read-ahead
1232 * mark the page may be partially dirty and thus
1233 * not freeable. Don't bother checking to see
1234 * if the pager has the page because we can't free
1235 * it anyway. We have to depend on the get_page
1236 * operation filling in any gaps whether there is
1237 * backing store or not.
984263bc 1238 */
1c9602b3 1239 rv = vm_pager_get_page(fs->object, &fs->m, seqaccess);
984263bc
MD
1240
1241 if (rv == VM_PAGER_OK) {
1242 /*
984263bc
MD
1243 * Relookup in case pager changed page. Pager
1244 * is responsible for disposition of old page
1245 * if moved.
06ecca5a
MD
1246 *
1247 * XXX other code segments do relookups too.
1248 * It's a bad abstraction that needs to be
1249 * fixed/removed.
984263bc 1250 */
72579d2e 1251 fs->m = vm_page_lookup(fs->object, pindex);
568e6804 1252 if (fs->m == NULL) {
9ad0147b 1253 lwkt_reltoken(&vm_token);
568e6804
MD
1254 unlock_and_deallocate(fs);
1255 return (KERN_TRY_AGAIN);
984263bc
MD
1256 }
1257
568e6804 1258 ++fs->hardfault;
984263bc
MD
1259 break; /* break to PAGE HAS BEEN FOUND */
1260 }
568e6804 1261
984263bc
MD
1262 /*
1263 * Remove the bogus page (which does not exist at this
1264 * object/offset); before doing so, we must get back
1265 * our object lock to preserve our invariant.
1266 *
1267 * Also wake up any other process that may want to bring
1268 * in this page.
1269 *
1270 * If this is the top-level object, we must leave the
1271 * busy page to prevent another process from rushing
1272 * past us, and inserting the page in that object at
1273 * the same time that we are.
1274 */
a0bc8638
MD
1275 if (rv == VM_PAGER_ERROR) {
1276 if (curproc)
086c1d7e 1277 kprintf("vm_fault: pager read error, pid %d (%s)\n", curproc->p_pid, curproc->p_comm);
a0bc8638 1278 else
086c1d7e 1279 kprintf("vm_fault: pager read error, thread %p (%s)\n", curthread, curproc->p_comm);
a0bc8638 1280 }
1b9d3514 1281
984263bc
MD
1282 /*
1283 * Data outside the range of the pager or an I/O error
a55afca2
MD
1284 *
1285 * The page may have been wired during the pagein,
1286 * e.g. by the buffer cache, and cannot simply be
1b9d3514 1287 * freed. Call vnode_pager_freepage() to deal with it.
984263bc
MD
1288 */
1289 /*
1290 * XXX - the check for kernel_map is a kludge to work
1291 * around having the machine panic on a kernel space
1292 * fault w/ I/O error.
1293 */
1b9d3514
MD
1294 if (((fs->map != &kernel_map) &&
1295 (rv == VM_PAGER_ERROR)) || (rv == VM_PAGER_BAD)) {
a55afca2 1296 vnode_pager_freepage(fs->m);
9ad0147b 1297 lwkt_reltoken(&vm_token);
568e6804
MD
1298 fs->m = NULL;
1299 unlock_and_deallocate(fs);
1300 if (rv == VM_PAGER_ERROR)
1301 return (KERN_FAILURE);
1302 else
1303 return (KERN_PROTECTION_FAILURE);
1304 /* NOT REACHED */
984263bc 1305 }
568e6804 1306 if (fs->object != fs->first_object) {
a55afca2 1307 vnode_pager_freepage(fs->m);
568e6804 1308 fs->m = NULL;
984263bc
MD
1309 /*
1310 * XXX - we cannot just fall out at this
1311 * point, m has been freed and is invalid!
1312 */
1313 }
1314 }
1315
1316 /*
568e6804 1317 * We get here if the object has a default pager (or unwiring)
984263bc
MD
1318 * or the pager doesn't have the page.
1319 */
568e6804
MD
1320 if (fs->object == fs->first_object)
1321 fs->first_m = fs->m;
984263bc
MD
1322
1323 /*
1324 * Move on to the next object. Lock the next object before
1325 * unlocking the current one.
1326 */
72579d2e 1327 pindex += OFF_TO_IDX(fs->object->backing_object_offset);
568e6804 1328 next_object = fs->object->backing_object;
984263bc
MD
1329 if (next_object == NULL) {
1330 /*
1331 * If there's no object left, fill the page in the top
1332 * object with zeros.
1333 */
568e6804
MD
1334 if (fs->object != fs->first_object) {
1335 vm_object_pip_wakeup(fs->object);
984263bc 1336
568e6804 1337 fs->object = fs->first_object;
72579d2e 1338 pindex = first_pindex;
568e6804 1339 fs->m = fs->first_m;
984263bc 1340 }
568e6804 1341 fs->first_m = NULL;
984263bc
MD
1342
1343 /*
1344 * Zero the page if necessary and mark it valid.
1345 */
568e6804
MD
1346 if ((fs->m->flags & PG_ZERO) == 0) {
1347 vm_page_zero_fill(fs->m);
984263bc 1348 } else {
12e4aaff 1349 mycpu->gd_cnt.v_ozfod++;
984263bc 1350 }
12e4aaff 1351 mycpu->gd_cnt.v_zfod++;
568e6804 1352 fs->m->valid = VM_PAGE_BITS_ALL;
984263bc 1353 break; /* break to PAGE HAS BEEN FOUND */
984263bc 1354 }
9ad0147b
MD
1355 if (fs->object != fs->first_object) {
1356 vm_object_pip_wakeup(fs->object);
1357 }
1358 KASSERT(fs->object != next_object,
1359 ("object loop %p", next_object));
1360 fs->object = next_object;
1361 vm_object_pip_add(fs->object, 1);
984263bc
MD
1362 }
1363
984263bc
MD
1364 /*
1365 * PAGE HAS BEEN FOUND. [Loop invariant still holds -- the object lock
1366 * is held.]
1b9d3514 1367 *
9ad0147b
MD
1368 * vm_token is still held
1369 *
984263bc
MD
1370 * If the page is being written, but isn't already owned by the
1371 * top-level object, we have to copy it into a new page owned by the
1372 * top-level object.
1373 */
1b9d3514
MD
1374 KASSERT((fs->m->flags & PG_BUSY) != 0,
1375 ("vm_fault: not busy after main loop"));
1376
568e6804 1377 if (fs->object != fs->first_object) {
984263bc
MD
1378 /*
1379 * We only really need to copy if we want to write it.
1380 */
984263bc
MD
1381 if (fault_type & VM_PROT_WRITE) {
1382 /*
1383 * This allows pages to be virtually copied from a
1384 * backing_object into the first_object, where the
1385 * backing object has no other refs to it, and cannot
1386 * gain any more refs. Instead of a bcopy, we just
1387 * move the page from the backing object to the
1388 * first object. Note that we must mark the page
1389 * dirty in the first object so that it will go out
1390 * to swap when needed.
1391 */
aa542ad5
MD
1392 if (
1393 /*
1394 * Map, if present, has not changed
1395 */
1396 (fs->map == NULL ||
1397 fs->map_generation == fs->map->timestamp) &&
984263bc
MD
1398 /*
1399 * Only one shadow object
1400 */
568e6804 1401 (fs->object->shadow_count == 1) &&
984263bc
MD
1402 /*
1403 * No COW refs, except us
1404 */
568e6804 1405 (fs->object->ref_count == 1) &&
984263bc
MD
1406 /*
1407 * No one else can look this object up
1408 */
568e6804 1409 (fs->object->handle == NULL) &&
984263bc
MD
1410 /*
1411 * No other ways to look the object up
1412 */
568e6804
MD
1413 ((fs->object->type == OBJT_DEFAULT) ||
1414 (fs->object->type == OBJT_SWAP)) &&
984263bc
MD
1415 /*
1416 * We don't chase down the shadow chain
1417 */
568e6804 1418 (fs->object == fs->first_object->backing_object) &&
984263bc
MD
1419
1420 /*
1421 * grab the lock if we need to
1422 */
568e6804 1423 (fs->lookup_still_valid ||
aa542ad5 1424 fs->map == NULL ||
568e6804 1425 lockmgr(&fs->map->lock, LK_EXCLUSIVE|LK_NOWAIT) == 0)
984263bc
MD
1426 ) {
1427
568e6804 1428 fs->lookup_still_valid = 1;
984263bc
MD
1429 /*
1430 * get rid of the unnecessary page
1431 */
568e6804
MD
1432 vm_page_protect(fs->first_m, VM_PROT_NONE);
1433 vm_page_free(fs->first_m);
1434 fs->first_m = NULL;
984263bc
MD
1435
1436 /*
1437 * grab the page and put it into the
1438 * process'es object. The page is
1439 * automatically made dirty.
1440 */
72579d2e 1441 vm_page_rename(fs->m, fs->first_object, first_pindex);
568e6804
MD
1442 fs->first_m = fs->m;
1443 vm_page_busy(fs->first_m);
1444 fs->m = NULL;
12e4aaff 1445 mycpu->gd_cnt.v_cow_optim++;
984263bc
MD
1446 } else {
1447 /*
1448 * Oh, well, lets copy it.
1449 */
568e6804 1450 vm_page_copy(fs->m, fs->first_m);
10192bae 1451 vm_page_event(fs->m, VMEVENT_COW);
984263bc
MD
1452 }
1453
568e6804 1454 if (fs->m) {
984263bc
MD
1455 /*
1456 * We no longer need the old page or object.
1457 */
568e6804 1458 release_page(fs);
984263bc
MD
1459 }
1460
1461 /*
568e6804 1462 * fs->object != fs->first_object due to above
984263bc
MD
1463 * conditional
1464 */
568e6804 1465 vm_object_pip_wakeup(fs->object);
984263bc
MD
1466
1467 /*
1468 * Only use the new page below...
1469 */
1470
12e4aaff 1471 mycpu->gd_cnt.v_cow_faults++;
568e6804
MD
1472 fs->m = fs->first_m;
1473 fs->object = fs->first_object;
72579d2e 1474 pindex = first_pindex;
984263bc 1475 } else {
568e6804
MD
1476 /*
1477 * If it wasn't a write fault avoid having to copy
1478 * the page by mapping it read-only.
1479 */
1480 fs->prot &= ~VM_PROT_WRITE;
984263bc
MD
1481 }
1482 }
1483
1484 /*
568e6804
MD
1485 * We may have had to unlock a map to do I/O. If we did then
1486 * lookup_still_valid will be FALSE. If the map generation count
1487 * also changed then all sorts of things could have happened while
1488 * we were doing the I/O and we need to retry.
984263bc
MD
1489 */
1490
568e6804 1491 if (!fs->lookup_still_valid &&
aa542ad5 1492 fs->map != NULL &&
568e6804
MD
1493 (fs->map->timestamp != fs->map_generation)) {
1494 release_page(fs);
9ad0147b 1495 lwkt_reltoken(&vm_token);
568e6804
MD
1496 unlock_and_deallocate(fs);
1497 return (KERN_TRY_AGAIN);
1498 }
1499
984263bc 1500 /*
17cde63e
MD
1501 * If the fault is a write, we know that this page is being
1502 * written NOW so dirty it explicitly to save on pmap_is_modified()
1503 * calls later.
1504 *
1505 * If this is a NOSYNC mmap we do not want to set PG_NOSYNC
1506 * if the page is already dirty to prevent data written with
1507 * the expectation of being synced from not being synced.
1508 * Likewise if this entry does not request NOSYNC then make
1509 * sure the page isn't marked NOSYNC. Applications sharing
1510 * data should use the same flags to avoid ping ponging.
1511 *
1512 * Also tell the backing pager, if any, that it should remove
1513 * any swap backing since the page is now dirty.
984263bc 1514 */
568e6804 1515 if (fs->prot & VM_PROT_WRITE) {
568e6804 1516 vm_object_set_writeable_dirty(fs->m->object);
568e6804
MD
1517 if (fs->entry->eflags & MAP_ENTRY_NOSYNC) {
1518 if (fs->m->dirty == 0)
1519 vm_page_flag_set(fs->m, PG_NOSYNC);
984263bc 1520 } else {
568e6804 1521 vm_page_flag_clear(fs->m, PG_NOSYNC);
984263bc 1522 }
568e6804 1523 if (fs->fault_flags & VM_FAULT_DIRTY) {
654a39f0 1524 crit_enter();
568e6804 1525 vm_page_dirty(fs->m);
107e9bcc 1526 swap_pager_unswapped(fs->m);
654a39f0 1527 crit_exit();
984263bc
MD
1528 }
1529 }
1530
9ad0147b
MD
1531 lwkt_reltoken(&vm_token);
1532
984263bc 1533 /*
75f59a66
MD
1534 * Page had better still be busy. We are still locked up and
1535 * fs->object will have another PIP reference if it is not equal
1536 * to fs->first_object.
984263bc 1537 */
568e6804
MD
1538 KASSERT(fs->m->flags & PG_BUSY,
1539 ("vm_fault: page %p not busy!", fs->m));
984263bc 1540
984263bc
MD
1541 /*
1542 * Sanity check: page must be completely valid or it is not fit to
1543 * map into user space. vm_pager_get_pages() ensures this.
1544 */
568e6804
MD
1545 if (fs->m->valid != VM_PAGE_BITS_ALL) {
1546 vm_page_zero_invalid(fs->m, TRUE);
086c1d7e 1547 kprintf("Warning: page %p partially invalid on fault\n", fs->m);
984263bc
MD
1548 }
1549
984263bc 1550 return (KERN_SUCCESS);
984263bc
MD
1551}
1552
1553/*
f2d22ebf
MD
1554 * Wire down a range of virtual addresses in a map. The entry in question
1555 * should be marked in-transition and the map must be locked. We must
1556 * release the map temporarily while faulting-in the page to avoid a
1557 * deadlock. Note that the entry may be clipped while we are blocked but
1558 * will never be freed.
9ad0147b
MD
1559 *
1560 * No requirements.
984263bc
MD
1561 */
1562int
f2d22ebf 1563vm_fault_wire(vm_map_t map, vm_map_entry_t entry, boolean_t user_wire)
984263bc 1564{
f2d22ebf
MD
1565 boolean_t fictitious;
1566 vm_offset_t start;
1567 vm_offset_t end;
5f910b2f 1568 vm_offset_t va;
f2d22ebf 1569 vm_paddr_t pa;
5f910b2f 1570 pmap_t pmap;
984263bc
MD
1571 int rv;
1572
1573 pmap = vm_map_pmap(map);
f2d22ebf
MD
1574 start = entry->start;
1575 end = entry->end;
1576 fictitious = entry->object.vm_object &&
1577 (entry->object.vm_object->type == OBJT_DEVICE);
984263bc 1578
9ad0147b 1579 lwkt_gettoken(&vm_token);
f2d22ebf
MD
1580 vm_map_unlock(map);
1581 map->timestamp++;
984263bc
MD
1582
1583 /*
984263bc
MD
1584 * We simulate a fault to get the page and enter it in the physical
1585 * map.
1586 */
1587 for (va = start; va < end; va += PAGE_SIZE) {
f2d22ebf
MD
1588 if (user_wire) {
1589 rv = vm_fault(map, va, VM_PROT_READ,
1590 VM_FAULT_USER_WIRE);
1591 } else {
1592 rv = vm_fault(map, va, VM_PROT_READ|VM_PROT_WRITE,
1593 VM_FAULT_CHANGE_WIRING);
1594 }
984263bc 1595 if (rv) {
f2d22ebf
MD
1596 while (va > start) {
1597 va -= PAGE_SIZE;
1598 if ((pa = pmap_extract(pmap, va)) == 0)
1599 continue;
1600 pmap_change_wiring(pmap, va, FALSE);
1601 if (!fictitious)
1602 vm_page_unwire(PHYS_TO_VM_PAGE(pa), 1);
1603 }
f2d22ebf 1604 vm_map_lock(map);
9ad0147b 1605 lwkt_reltoken(&vm_token);
984263bc
MD
1606 return (rv);
1607 }
1608 }
f2d22ebf 1609 vm_map_lock(map);
9ad0147b 1610 lwkt_reltoken(&vm_token);
984263bc
MD
1611 return (KERN_SUCCESS);
1612}
1613
984263bc 1614/*
f2d22ebf
MD
1615 * Unwire a range of virtual addresses in a map. The map should be
1616 * locked.
984263bc
MD
1617 */
1618void
f2d22ebf 1619vm_fault_unwire(vm_map_t map, vm_map_entry_t entry)
984263bc 1620{
f2d22ebf
MD
1621 boolean_t fictitious;
1622 vm_offset_t start;
1623 vm_offset_t end;
6ef943a3
MD
1624 vm_offset_t va;
1625 vm_paddr_t pa;
5f910b2f 1626 pmap_t pmap;
984263bc
MD
1627
1628 pmap = vm_map_pmap(map);
f2d22ebf
MD
1629 start = entry->start;
1630 end = entry->end;
1631 fictitious = entry->object.vm_object &&
1632 (entry->object.vm_object->type == OBJT_DEVICE);
984263bc
MD
1633
1634 /*
1635 * Since the pages are wired down, we must be able to get their
1636 * mappings from the physical map system.
1637 */
9ad0147b 1638 lwkt_gettoken(&vm_token);
984263bc
MD
1639 for (va = start; va < end; va += PAGE_SIZE) {
1640 pa = pmap_extract(pmap, va);
6ef943a3 1641 if (pa != 0) {
984263bc 1642 pmap_change_wiring(pmap, va, FALSE);
f2d22ebf
MD
1643 if (!fictitious)
1644 vm_page_unwire(PHYS_TO_VM_PAGE(pa), 1);
984263bc
MD
1645 }
1646 }
9ad0147b 1647 lwkt_reltoken(&vm_token);
984263bc
MD
1648}
1649
1650/*
46311ac2
MD
1651 * Reduce the rate at which memory is allocated to a process based
1652 * on the perceived load on the VM system. As the load increases
1653 * the allocation burst rate goes down and the delay increases.
1654 *
1655 * Rate limiting does not apply when faulting active or inactive
1656 * pages. When faulting 'cache' pages, rate limiting only applies
1657 * if the system currently has a severe page deficit.
1658 *
1659 * XXX vm_pagesupply should be increased when a page is freed.
1660 *
1661 * We sleep up to 1/10 of a second.
1662 */
1663static int
1664vm_fault_ratelimit(struct vmspace *vmspace)
1665{
1666 if (vm_load_enable == 0)
1667 return(0);
1668 if (vmspace->vm_pagesupply > 0) {
9ad0147b 1669 --vmspace->vm_pagesupply; /* SMP race ok */
46311ac2
MD
1670 return(0);
1671 }
1672#ifdef INVARIANTS
1673 if (vm_load_debug) {
086c1d7e 1674 kprintf("load %-4d give %d pgs, wait %d, pid %-5d (%s)\n",
46311ac2
MD
1675 vm_load,
1676 (1000 - vm_load ) / 10, vm_load * hz / 10000,
1677 curproc->p_pid, curproc->p_comm);
1678 }
1679#endif
1680 vmspace->vm_pagesupply = (1000 - vm_load) / 10;
1681 return(vm_load * hz / 10000);
1682}
1683
1684/*
9ad0147b
MD
1685 * Copy all of the pages from a wired-down map entry to another.
1686 *
1687 * The source and destination maps must be locked for write.
1688 * The source map entry must be wired down (or be a sharing map
1689 * entry corresponding to a main map entry that is wired down).
984263bc 1690 *
9ad0147b 1691 * No other requirements.
984263bc 1692 */
984263bc 1693void
57e43348 1694vm_fault_copy_entry(vm_map_t dst_map, vm_map_t src_map,
9ad0147b 1695 vm_map_entry_t dst_entry, vm_map_entry_t src_entry)
984263bc
MD
1696{
1697 vm_object_t dst_object;
1698 vm_object_t src_object;
1699 vm_ooffset_t dst_offset;
1700 vm_ooffset_t src_offset;
1701 vm_prot_t prot;
1702 vm_offset_t vaddr;
1703 vm_page_t dst_m;
1704 vm_page_t src_m;
1705
1706#ifdef lint
1707 src_map++;
1708#endif /* lint */
1709
1710 src_object = src_entry->object.vm_object;
1711 src_offset = src_entry->offset;
1712
1713 /*
1714 * Create the top-level object for the destination entry. (Doesn't
1715 * actually shadow anything - we copy the pages directly.)
1716 */
53025830
MD
1717 vm_map_entry_allocate_object(dst_entry);
1718 dst_object = dst_entry->object.vm_object;
984263bc
MD
1719
1720 prot = dst_entry->max_protection;
1721
1722 /*
1723 * Loop through all of the pages in the entry's range, copying each
1724 * one from the source object (it should be there) to the destination
1725 * object.
1726 */
1727 for (vaddr = dst_entry->start, dst_offset = 0;
1728 vaddr < dst_entry->end;
1729 vaddr += PAGE_SIZE, dst_offset += PAGE_SIZE) {
1730
1731 /*
1732 * Allocate a page in the destination object
1733 */
1734 do {
1735 dst_m = vm_page_alloc(dst_object,
1736 OFF_TO_IDX(dst_offset), VM_ALLOC_NORMAL);
1737 if (dst_m == NULL) {
4ecf7cc9 1738 vm_wait(0);
984263bc
MD
1739 }
1740 } while (dst_m == NULL);
1741
1742 /*
1743 * Find the page in the source object, and copy it in.
1744 * (Because the source is wired down, the page will be in
1745 * memory.)
1746 */
1747 src_m = vm_page_lookup(src_object,
1748 OFF_TO_IDX(dst_offset + src_offset));
1749 if (src_m == NULL)
1750 panic("vm_fault_copy_wired: page missing");
1751
1752 vm_page_copy(src_m, dst_m);
10192bae 1753 vm_page_event(src_m, VMEVENT_COW);
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1754
1755 /*
1756 * Enter it in the pmap...
1757 */
1758
1759 vm_page_flag_clear(dst_m, PG_ZERO);
1760 pmap_enter(dst_map->pmap, vaddr, dst_m, prot, FALSE);
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1761
1762 /*
1763 * Mark it no longer busy, and put it on the active list.
1764 */
1765 vm_page_activate(dst_m);
1766 vm_page_wakeup(dst_m);
1767 }
1768}
1769
1b9d3514 1770#if 0
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1771
1772/*
1773 * This routine checks around the requested page for other pages that
1774 * might be able to be faulted in. This routine brackets the viable
1775 * pages for the pages to be paged in.
1776 *
1777 * Inputs:
1778 * m, rbehind, rahead
1779 *
1780 * Outputs:
1781 * marray (array of vm_page_t), reqpage (index of requested page)
1782 *
1783 * Return value:
1784 * number of pages in marray
1785 */
1786static int
57e43348 1787vm_fault_additional_pages(vm_page_t m, int rbehind, int rahead,
bc823b32 1788 vm_page_t *marray, int *reqpage)
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1789{
1790 int i,j;
1791 vm_object_t object;
1792 vm_pindex_t pindex, startpindex, endpindex, tpindex;
1793 vm_page_t rtm;
1794 int cbehind, cahead;
1795
1796 object = m->object;
1797 pindex = m->pindex;
1798
1799 /*
1800 * we don't fault-ahead for device pager
1801 */
1802 if (object->type == OBJT_DEVICE) {
1803 *reqpage = 0;
1804 marray[0] = m;
1805 return 1;
1806 }
1807
1808 /*
1809 * if the requested page is not available, then give up now
1810 */
984263bc 1811 if (!vm_pager_has_page(object, pindex, &cbehind, &cahead)) {
17cde63e 1812 *reqpage = 0; /* not used by caller, fix compiler warn */
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1813 return 0;
1814 }
1815
1816 if ((cbehind == 0) && (cahead == 0)) {
1817 *reqpage = 0;
1818 marray[0] = m;
1819 return 1;
1820 }
1821
1822 if (rahead > cahead) {
1823 rahead = cahead;
1824 }
1825
1826 if (rbehind > cbehind) {
1827 rbehind = cbehind;
1828 }
1829
1830 /*
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1831 * Do not do any readahead if we have insufficient free memory.
1832 *
1833 * XXX code was broken disabled before and has instability
1834 * with this conditonal fixed, so shortcut for now.
984263bc 1835 */
bc823b32 1836 if (burst_fault == 0 || vm_page_count_severe()) {
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1837 marray[0] = m;
1838 *reqpage = 0;
1839 return 1;
1840 }
1841
1842 /*
1843 * scan backward for the read behind pages -- in memory
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1844 *
1845 * Assume that if the page is not found an interrupt will not
1846 * create it. Theoretically interrupts can only remove (busy)
1847 * pages, not create new associations.
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1848 */
1849 if (pindex > 0) {
1850 if (rbehind > pindex) {
1851 rbehind = pindex;
1852 startpindex = 0;
1853 } else {
1854 startpindex = pindex - rbehind;
1855 }
1856
654a39f0 1857 crit_enter();
9ad0147b 1858 lwkt_gettoken(&vm_token);
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1859 for (tpindex = pindex; tpindex > startpindex; --tpindex) {
1860 if (vm_page_lookup(object, tpindex - 1))
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1861 break;
1862 }
1863
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1864 i = 0;
1865 while (tpindex < pindex) {
1866 rtm = vm_page_alloc(object, tpindex, VM_ALLOC_SYSTEM);
984263bc 1867 if (rtm == NULL) {
9ad0147b 1868 lwkt_reltoken(&vm_token);
654a39f0 1869 crit_exit();
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1870 for (j = 0; j < i; j++) {
1871 vm_page_free(marray[j]);
1872 }
1873 marray[0] = m;
1874 *reqpage = 0;
1875 return 1;
1876 }
984263bc 1877 marray[i] = rtm;
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1878 ++i;
1879 ++tpindex;
984263bc 1880 }
9ad0147b 1881 lwkt_reltoken(&vm_token);
654a39f0 1882 crit_exit();
984263bc 1883 } else {
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1884 i = 0;
1885 }
1886
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1887 /*
1888 * Assign requested page
1889 */
984263bc 1890 marray[i] = m;
984263bc 1891 *reqpage = i;
bc823b32 1892 ++i;
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1893
1894 /*
bc823b32 1895 * Scan forwards for read-ahead pages
984263bc 1896 */
bc823b32 1897 tpindex = pindex + 1;
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1898 endpindex = tpindex + rahead;
1899 if (endpindex > object->size)
1900 endpindex = object->size;
1901
654a39f0 1902 crit_enter();
9ad0147b 1903 lwkt_gettoken(&vm_token);
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1904 while (tpindex < endpindex) {
1905 if (vm_page_lookup(object, tpindex))
984263bc 1906 break;
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1907 rtm = vm_page_alloc(object, tpindex, VM_ALLOC_SYSTEM);
1908 if (rtm == NULL)
984263bc 1909 break;
984263bc 1910 marray[i] = rtm;
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1911 ++i;
1912 ++tpindex;
984263bc 1913 }
9ad0147b 1914 lwkt_reltoken(&vm_token);
654a39f0 1915 crit_exit();
984263bc 1916
bc823b32 1917 return (i);
984263bc 1918}
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1919
1920#endif
1921
1922/*
1923 * vm_prefault() provides a quick way of clustering pagefaults into a
1924 * processes address space. It is a "cousin" of pmap_object_init_pt,
1925 * except it runs at page fault time instead of mmap time.
1926 *
1927 * This code used to be per-platform pmap_prefault(). It is now
1928 * machine-independent and enhanced to also pre-fault zero-fill pages
1929 * (see vm.fast_fault) as well as make them writable, which greatly
1930 * reduces the number of page faults programs incur.
1931 *
1932 * Application performance when pre-faulting zero-fill pages is heavily
1933 * dependent on the application. Very tiny applications like /bin/echo
1934 * lose a little performance while applications of any appreciable size
1935 * gain performance. Prefaulting multiple pages also reduces SMP
1936 * congestion and can improve SMP performance significantly.
1937 *
1938 * NOTE! prot may allow writing but this only applies to the top level
1939 * object. If we wind up mapping a page extracted from a backing
1940 * object we have to make sure it is read-only.
1941 *
1942 * NOTE! The caller has already handled any COW operations on the
1943 * vm_map_entry via the normal fault code. Do NOT call this
1944 * shortcut unless the normal fault code has run on this entry.
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1945 *
1946 * No other requirements.
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1947 */
1948#define PFBAK 4
1949#define PFFOR 4
1950#define PAGEORDER_SIZE (PFBAK+PFFOR)
1951
1952static int vm_prefault_pageorder[] = {
1953 -PAGE_SIZE, PAGE_SIZE,
1954 -2 * PAGE_SIZE, 2 * PAGE_SIZE,
1955 -3 * PAGE_SIZE, 3 * PAGE_SIZE,
1956 -4 * PAGE_SIZE, 4 * PAGE_SIZE
1957};
1958
1959static void
1960vm_prefault(pmap_t pmap, vm_offset_t addra, vm_map_entry_t entry, int prot)
1961{
1962 struct lwp *lp;
1963 vm_page_t m;
1964 vm_offset_t starta;
1965 vm_offset_t addr;
1966 vm_pindex_t index;
1967 vm_pindex_t pindex;
1968 vm_object_t object;
1969 int pprot;
1970 int i;
1971
1972 /*
1973 * We do not currently prefault mappings that use virtual page
1974 * tables. We do not prefault foreign pmaps.
1975 */
1976 if (entry->maptype == VM_MAPTYPE_VPAGETABLE)
1977 return;
1978 lp = curthread->td_lwp;
1979 if (lp == NULL || (pmap != vmspace_pmap(lp->lwp_vmspace)))
1980 return;
1981
1982 object = entry->object.vm_object;
1983
1984 starta = addra - PFBAK * PAGE_SIZE;
1985 if (starta < entry->start)
1986 starta = entry->start;
1987 else if (starta > addra)
1988 starta = 0;
1989
1990 /*
1991 * critical section protection is required to maintain the
1992 * page/object association, interrupts can free pages and remove
1993 * them from their objects.
1994 */
1995 crit_enter();
9ad0147b 1996 lwkt_gettoken(&vm_token);
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1997 for (i = 0; i < PAGEORDER_SIZE; i++) {
1998 vm_object_t lobject;
3bb7eedb 1999 int allocated = 0;
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2000
2001 addr = addra + vm_prefault_pageorder[i];
2002 if (addr > addra + (PFFOR * PAGE_SIZE))
2003 addr = 0;
2004
2005 if (addr < starta || addr >= entry->end)
2006 continue;
2007
2008 if (pmap_prefault_ok(pmap, addr) == 0)
2009 continue;
2010
2011 /*
2012 * Follow the VM object chain to obtain the page to be mapped
2013 * into the pmap.
2014 *
2015 * If we reach the terminal object without finding a page
2016 * and we determine it would be advantageous, then allocate
2017 * a zero-fill page for the base object. The base object
2018 * is guaranteed to be OBJT_DEFAULT for this case.
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2019 *
2020 * In order to not have to check the pager via *haspage*()
2021 * we stop if any non-default object is encountered. e.g.
2022 * a vnode or swap object would stop the loop.
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2023 */
2024 index = ((addr - entry->start) + entry->offset) >> PAGE_SHIFT;
2025 lobject = object;
2026 pindex = index;
2027 pprot = prot;
2028
2029 while ((m = vm_page_lookup(lobject, pindex)) == NULL) {
2030 if (lobject->type != OBJT_DEFAULT)
2031 break;
2032 if (lobject->backing_object == NULL) {
2033 if (vm_fast_fault == 0)
2034 break;
2035 if (vm_prefault_pageorder[i] < 0 ||
2036 (prot & VM_PROT_WRITE) == 0 ||
2037 vm_page_count_min(0)) {
2038 break;
2039 }
3bb7eedb 2040 /* note: allocate from base object */
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2041 m = vm_page_alloc(object, index,
2042 VM_ALLOC_NORMAL | VM_ALLOC_ZERO);
2043
2044 if ((m->flags & PG_ZERO) == 0) {
2045 vm_page_zero_fill(m);
2046 } else {
2047 vm_page_flag_clear(m, PG_ZERO);
2048 mycpu->gd_cnt.v_ozfod++;
2049 }
2050 mycpu->gd_cnt.v_zfod++;
2051 m->valid = VM_PAGE_BITS_ALL;
3bb7eedb 2052 allocated = 1;
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2053 pprot = prot;
2054 /* lobject = object .. not needed */
2055 break;
2056 }
2057 if (lobject->backing_object_offset & PAGE_MASK)
2058 break;
2059 pindex += lobject->backing_object_offset >> PAGE_SHIFT;
2060 lobject = lobject->backing_object;
2061 pprot &= ~VM_PROT_WRITE;
2062 }
2063 /*
2064 * NOTE: lobject now invalid (if we did a zero-fill we didn't
2065 * bother assigning lobject = object).
2066 *
2067 * Give-up if the page is not available.
2068 */
2069 if (m == NULL)
2070 break;
2071
2072 /*
2073 * Do not conditionalize on PG_RAM. If pages are present in
2074 * the VM system we assume optimal caching. If caching is
2075 * not optimal the I/O gravy train will be restarted when we
2076 * hit an unavailable page. We do not want to try to restart
2077 * the gravy train now because we really don't know how much
2078 * of the object has been cached. The cost for restarting
2079 * the gravy train should be low (since accesses will likely
2080 * be I/O bound anyway).
2081 *
2082 * The object must be marked dirty if we are mapping a
2083 * writable page.
2084 */
2085 if (pprot & VM_PROT_WRITE)
2086 vm_object_set_writeable_dirty(m->object);
2087
2088 /*
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2089 * Enter the page into the pmap if appropriate. If we had
2090 * allocated the page we have to place it on a queue. If not
2091 * we just have to make sure it isn't on the cache queue
2092 * (pages on the cache queue are not allowed to be mapped).
1b9d3514 2093 */
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MD
2094 if (allocated) {
2095 pmap_enter(pmap, addr, m, pprot, 0);
2096 vm_page_deactivate(m);
2097 vm_page_wakeup(m);
2098 } else if (((m->valid & VM_PAGE_BITS_ALL) == VM_PAGE_BITS_ALL) &&
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2099 (m->busy == 0) &&
2100 (m->flags & (PG_BUSY | PG_FICTITIOUS)) == 0) {
2101
2102 if ((m->queue - m->pc) == PQ_CACHE) {
2103 vm_page_deactivate(m);
2104 }
2105 vm_page_busy(m);
2106 pmap_enter(pmap, addr, m, pprot, 0);
2107 vm_page_wakeup(m);
2108 }
2109 }
9ad0147b 2110 lwkt_reltoken(&vm_token);
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2111 crit_exit();
2112}