| 1 | /* |
| 2 | * (MPSAFE) |
| 3 | * |
| 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 $ |
| 72 | * $DragonFly: src/sys/vm/vm_fault.c,v 1.47 2008/07/01 02:02:56 dillon Exp $ |
| 73 | */ |
| 74 | |
| 75 | /* |
| 76 | * Page fault handling module. |
| 77 | */ |
| 78 | |
| 79 | #include <sys/param.h> |
| 80 | #include <sys/systm.h> |
| 81 | #include <sys/kernel.h> |
| 82 | #include <sys/proc.h> |
| 83 | #include <sys/vnode.h> |
| 84 | #include <sys/resourcevar.h> |
| 85 | #include <sys/vmmeter.h> |
| 86 | #include <sys/vkernel.h> |
| 87 | #include <sys/lock.h> |
| 88 | #include <sys/sysctl.h> |
| 89 | |
| 90 | #include <cpu/lwbuf.h> |
| 91 | |
| 92 | #include <vm/vm.h> |
| 93 | #include <vm/vm_param.h> |
| 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> |
| 103 | |
| 104 | #include <sys/thread2.h> |
| 105 | #include <vm/vm_page2.h> |
| 106 | |
| 107 | struct faultstate { |
| 108 | vm_page_t m; |
| 109 | vm_object_t object; |
| 110 | vm_pindex_t pindex; |
| 111 | vm_prot_t prot; |
| 112 | vm_page_t first_m; |
| 113 | vm_object_t first_object; |
| 114 | vm_prot_t first_prot; |
| 115 | vm_map_t map; |
| 116 | vm_map_entry_t entry; |
| 117 | int lookup_still_valid; |
| 118 | int didlimit; |
| 119 | int hardfault; |
| 120 | int fault_flags; |
| 121 | int map_generation; |
| 122 | boolean_t wired; |
| 123 | struct vnode *vp; |
| 124 | }; |
| 125 | |
| 126 | static int vm_fast_fault = 1; |
| 127 | SYSCTL_INT(_vm, OID_AUTO, fast_fault, CTLFLAG_RW, &vm_fast_fault, 0, ""); |
| 128 | static int debug_cluster = 0; |
| 129 | SYSCTL_INT(_vm, OID_AUTO, debug_cluster, CTLFLAG_RW, &debug_cluster, 0, ""); |
| 130 | |
| 131 | static int vm_fault_object(struct faultstate *, vm_pindex_t, vm_prot_t); |
| 132 | static int vm_fault_vpagetable(struct faultstate *, vm_pindex_t *, vpte_t, int); |
| 133 | #if 0 |
| 134 | static int vm_fault_additional_pages (vm_page_t, int, int, vm_page_t *, int *); |
| 135 | #endif |
| 136 | static int vm_fault_ratelimit(struct vmspace *); |
| 137 | static void vm_prefault(pmap_t pmap, vm_offset_t addra, vm_map_entry_t entry, |
| 138 | int prot); |
| 139 | |
| 140 | /* |
| 141 | * The caller must hold vm_token. |
| 142 | */ |
| 143 | static __inline void |
| 144 | release_page(struct faultstate *fs) |
| 145 | { |
| 146 | vm_page_deactivate(fs->m); |
| 147 | vm_page_wakeup(fs->m); |
| 148 | fs->m = NULL; |
| 149 | } |
| 150 | |
| 151 | /* |
| 152 | * The caller must hold vm_token. |
| 153 | */ |
| 154 | static __inline void |
| 155 | unlock_map(struct faultstate *fs) |
| 156 | { |
| 157 | if (fs->lookup_still_valid && fs->map) { |
| 158 | vm_map_lookup_done(fs->map, fs->entry, 0); |
| 159 | fs->lookup_still_valid = FALSE; |
| 160 | } |
| 161 | } |
| 162 | |
| 163 | /* |
| 164 | * Clean up after a successful call to vm_fault_object() so another call |
| 165 | * to vm_fault_object() can be made. |
| 166 | * |
| 167 | * The caller must hold vm_token. |
| 168 | */ |
| 169 | static void |
| 170 | _cleanup_successful_fault(struct faultstate *fs, int relock) |
| 171 | { |
| 172 | if (fs->object != fs->first_object) { |
| 173 | vm_page_free(fs->first_m); |
| 174 | vm_object_pip_wakeup(fs->object); |
| 175 | fs->first_m = NULL; |
| 176 | } |
| 177 | fs->object = fs->first_object; |
| 178 | if (relock && fs->lookup_still_valid == FALSE) { |
| 179 | if (fs->map) |
| 180 | vm_map_lock_read(fs->map); |
| 181 | fs->lookup_still_valid = TRUE; |
| 182 | } |
| 183 | } |
| 184 | |
| 185 | /* |
| 186 | * The caller must hold vm_token. |
| 187 | */ |
| 188 | static void |
| 189 | _unlock_things(struct faultstate *fs, int dealloc) |
| 190 | { |
| 191 | vm_object_pip_wakeup(fs->first_object); |
| 192 | _cleanup_successful_fault(fs, 0); |
| 193 | if (dealloc) { |
| 194 | vm_object_deallocate(fs->first_object); |
| 195 | fs->first_object = NULL; |
| 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) |
| 206 | #define cleanup_successful_fault(fs) _cleanup_successful_fault(fs, 1) |
| 207 | |
| 208 | /* |
| 209 | * TRYPAGER |
| 210 | * |
| 211 | * Determine if the pager for the current object *might* contain the page. |
| 212 | * |
| 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. |
| 216 | */ |
| 217 | #define TRYPAGER(fs) \ |
| 218 | (fs->object->type != OBJT_DEFAULT && \ |
| 219 | (((fs->fault_flags & VM_FAULT_WIRE_MASK) == 0) || fs->wired)) |
| 220 | |
| 221 | /* |
| 222 | * vm_fault: |
| 223 | * |
| 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. |
| 227 | * |
| 228 | * NOTE: The given address should be truncated to the proper page address. |
| 229 | * |
| 230 | * KERN_SUCCESS is returned if the page fault is handled; otherwise, |
| 231 | * a standard error specifying why the fault is fatal is returned. |
| 232 | * |
| 233 | * The map in question must be referenced, and remains so. |
| 234 | * The caller may hold no locks. |
| 235 | * No other requirements. |
| 236 | */ |
| 237 | int |
| 238 | vm_fault(vm_map_t map, vm_offset_t vaddr, vm_prot_t fault_type, int fault_flags) |
| 239 | { |
| 240 | int result; |
| 241 | vm_pindex_t first_pindex; |
| 242 | struct faultstate fs; |
| 243 | int growstack; |
| 244 | |
| 245 | mycpu->gd_cnt.v_vm_faults++; |
| 246 | |
| 247 | fs.didlimit = 0; |
| 248 | fs.hardfault = 0; |
| 249 | fs.fault_flags = fault_flags; |
| 250 | growstack = 1; |
| 251 | |
| 252 | RetryFault: |
| 253 | /* |
| 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 | * |
| 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. |
| 266 | */ |
| 267 | fs.map = map; |
| 268 | result = vm_map_lookup(&fs.map, vaddr, fault_type, |
| 269 | &fs.entry, &fs.first_object, |
| 270 | &first_pindex, &fs.first_prot, &fs.wired); |
| 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) { |
| 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 | } |
| 291 | |
| 292 | /* |
| 293 | * If we are user-wiring a r/w segment, and it is COW, then |
| 294 | * we need to do the COW operation. Note that we don't |
| 295 | * currently COW RO sections now, because it is NOT desirable |
| 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, |
| 300 | VM_PROT_READ|VM_PROT_WRITE| |
| 301 | VM_PROT_OVERRIDE_WRITE, |
| 302 | &fs.entry, &fs.first_object, |
| 303 | &first_pindex, &fs.first_prot, |
| 304 | &fs.wired); |
| 305 | if (result != KERN_SUCCESS) |
| 306 | return result; |
| 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 | |
| 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; |
| 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 | /* |
| 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 | /* |
| 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. |
| 347 | * |
| 348 | * The vm_token is needed to manipulate the vm_object |
| 349 | */ |
| 350 | lwkt_gettoken(&vm_token); |
| 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); |
| 354 | lwkt_reltoken(&vm_token); |
| 355 | |
| 356 | fs.lookup_still_valid = TRUE; |
| 357 | fs.first_m = NULL; |
| 358 | fs.object = fs.first_object; /* so unlock_and_deallocate works */ |
| 359 | |
| 360 | /* |
| 361 | * If the entry is wired we cannot change the page protection. |
| 362 | */ |
| 363 | if (fs.wired) |
| 364 | fault_type = fs.first_prot; |
| 365 | |
| 366 | /* |
| 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 |
| 373 | */ |
| 374 | if (fs.entry->maptype == VM_MAPTYPE_VPAGETABLE) { |
| 375 | result = vm_fault_vpagetable(&fs, &first_pindex, |
| 376 | fs.entry->aux.master_pde, |
| 377 | fault_type); |
| 378 | if (result == KERN_TRY_AGAIN) |
| 379 | goto RetryFault; |
| 380 | if (result != KERN_SUCCESS) |
| 381 | return (result); |
| 382 | } |
| 383 | |
| 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 |
| 387 | * data. If it succeeds everything remains locked and fs->object |
| 388 | * will have an additional PIP count if it is not equal to |
| 389 | * fs->first_object |
| 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. |
| 396 | */ |
| 397 | result = vm_fault_object(&fs, first_pindex, fault_type); |
| 398 | |
| 399 | if (result == KERN_TRY_AGAIN) |
| 400 | goto RetryFault; |
| 401 | if (result != KERN_SUCCESS) |
| 402 | return (result); |
| 403 | |
| 404 | /* |
| 405 | * On success vm_fault_object() does not unlock or deallocate, and fs.m |
| 406 | * will contain a busied page. |
| 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 | |
| 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 | } |
| 421 | } |
| 422 | unlock_things(&fs); |
| 423 | |
| 424 | vm_page_flag_clear(fs.m, PG_ZERO); |
| 425 | vm_page_flag_set(fs.m, PG_REFERENCED); |
| 426 | |
| 427 | /* |
| 428 | * If the page is not wired down, then put it where the pageout daemon |
| 429 | * can find it. |
| 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. |
| 433 | */ |
| 434 | lwkt_gettoken(&vm_token); |
| 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 | |
| 444 | if (curthread->td_lwp) { |
| 445 | if (fs.hardfault) { |
| 446 | curthread->td_lwp->lwp_ru.ru_majflt++; |
| 447 | } else { |
| 448 | curthread->td_lwp->lwp_ru.ru_minflt++; |
| 449 | } |
| 450 | } |
| 451 | |
| 452 | /* |
| 453 | * Unlock everything, and return |
| 454 | */ |
| 455 | vm_page_wakeup(fs.m); |
| 456 | vm_object_deallocate(fs.first_object); |
| 457 | lwkt_reltoken(&vm_token); |
| 458 | |
| 459 | return (KERN_SUCCESS); |
| 460 | } |
| 461 | |
| 462 | /* |
| 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. |
| 466 | * |
| 467 | * No requirements. |
| 468 | */ |
| 469 | vm_page_t |
| 470 | vm_fault_page_quick(vm_offset_t va, vm_prot_t fault_type, int *errorp) |
| 471 | { |
| 472 | struct lwp *lp = curthread->td_lwp; |
| 473 | vm_page_t m; |
| 474 | |
| 475 | m = vm_fault_page(&lp->lwp_vmspace->vm_map, va, |
| 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 |
| 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 | * |
| 486 | * The returned page will be properly dirtied if VM_PROT_WRITE was specified, |
| 487 | * and marked PG_REFERENCED as well. |
| 488 | * |
| 489 | * If the page cannot be faulted writable and VM_PROT_WRITE was specified, an |
| 490 | * error will be returned. |
| 491 | * |
| 492 | * No requirements. |
| 493 | */ |
| 494 | vm_page_t |
| 495 | vm_fault_page(vm_map_t map, vm_offset_t vaddr, vm_prot_t fault_type, |
| 496 | int fault_flags, int *errorp) |
| 497 | { |
| 498 | vm_pindex_t first_pindex; |
| 499 | struct faultstate fs; |
| 500 | int result; |
| 501 | vm_prot_t orig_fault_type = fault_type; |
| 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 | |
| 510 | RetryFault: |
| 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. |
| 564 | * |
| 565 | * The vm_token is needed to manipulate the vm_object |
| 566 | */ |
| 567 | lwkt_gettoken(&vm_token); |
| 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); |
| 571 | lwkt_reltoken(&vm_token); |
| 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, |
| 593 | fs.entry->aux.master_pde, |
| 594 | fault_type); |
| 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 | |
| 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 | |
| 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 |
| 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). |
| 638 | */ |
| 639 | lwkt_gettoken(&vm_token); |
| 640 | vm_page_hold(fs.m); |
| 641 | vm_page_flag_clear(fs.m, PG_ZERO); |
| 642 | if (fault_type & VM_PROT_WRITE) |
| 643 | vm_page_dirty(fs.m); |
| 644 | |
| 645 | /* |
| 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); |
| 651 | vm_page_flag_set(fs.m, PG_REFERENCED); |
| 652 | |
| 653 | /* |
| 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); |
| 672 | lwkt_reltoken(&vm_token); |
| 673 | |
| 674 | *errorp = 0; |
| 675 | return(fs.m); |
| 676 | } |
| 677 | |
| 678 | /* |
| 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. |
| 682 | * |
| 683 | * A held (but not busied) page is returned. |
| 684 | * |
| 685 | * No requirements. |
| 686 | */ |
| 687 | vm_page_t |
| 688 | vm_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 | |
| 707 | RetryFault: |
| 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 | */ |
| 726 | lwkt_gettoken(&vm_token); |
| 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); |
| 730 | lwkt_reltoken(&vm_token); |
| 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 | |
| 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 | |
| 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 | */ |
| 786 | lwkt_gettoken(&vm_token); |
| 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); |
| 817 | lwkt_reltoken(&vm_token); |
| 818 | |
| 819 | *errorp = 0; |
| 820 | return(fs.m); |
| 821 | } |
| 822 | |
| 823 | /* |
| 824 | * Translate the virtual page number (first_pindex) that is relative |
| 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). |
| 831 | * |
| 832 | * No requirements (vm_token need not be held). |
| 833 | */ |
| 834 | static |
| 835 | int |
| 836 | vm_fault_vpagetable(struct faultstate *fs, vm_pindex_t *pindex, |
| 837 | vpte_t vpte, int fault_type) |
| 838 | { |
| 839 | struct lwbuf *lwb; |
| 840 | int vshift = VPTE_FRAME_END - PAGE_SHIFT; /* index bits remaining */ |
| 841 | int result = KERN_SUCCESS; |
| 842 | vpte_t *ptep; |
| 843 | |
| 844 | for (;;) { |
| 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 | */ |
| 849 | if ((vpte & VPTE_V) == 0) { |
| 850 | unlock_and_deallocate(fs); |
| 851 | return (KERN_FAILURE); |
| 852 | } |
| 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 | } |
| 861 | if ((vpte & VPTE_PS) || vshift == 0) |
| 862 | break; |
| 863 | KKASSERT(vshift >= VPTE_PAGE_BITS); |
| 864 | |
| 865 | /* |
| 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. |
| 871 | */ |
| 872 | result = vm_fault_object(fs, (vpte & VPTE_FRAME) >> PAGE_SHIFT, |
| 873 | VM_PROT_READ|VM_PROT_WRITE); |
| 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; |
| 882 | lwb = lwbuf_alloc(fs->m); |
| 883 | ptep = ((vpte_t *)lwbuf_kva(lwb) + |
| 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)) { |
| 897 | if ((vpte & (VPTE_M|VPTE_A)) != (VPTE_M|VPTE_A)) { |
| 898 | atomic_set_long(ptep, VPTE_M | VPTE_A); |
| 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) { |
| 905 | atomic_set_long(ptep, VPTE_A); |
| 906 | vm_page_dirty(fs->m); |
| 907 | } |
| 908 | } |
| 909 | lwbuf_free(lwb); |
| 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 | } |
| 915 | /* |
| 916 | * Combine remaining address bits with the vpte. |
| 917 | */ |
| 918 | /* JG how many bits from each? */ |
| 919 | *pindex = ((vpte & VPTE_FRAME) >> PAGE_SHIFT) + |
| 920 | (*pindex & ((1L << vshift) - 1)); |
| 921 | return (KERN_SUCCESS); |
| 922 | } |
| 923 | |
| 924 | |
| 925 | /* |
| 926 | * This is the core of the vm_fault code. |
| 927 | * |
| 928 | * Do all operations required to fault-in (fs.first_object, pindex). Run |
| 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 |
| 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. |
| 938 | * |
| 939 | * No requirements. |
| 940 | */ |
| 941 | static |
| 942 | int |
| 943 | vm_fault_object(struct faultstate *fs, |
| 944 | vm_pindex_t first_pindex, vm_prot_t fault_type) |
| 945 | { |
| 946 | vm_object_t next_object; |
| 947 | vm_pindex_t pindex; |
| 948 | |
| 949 | fs->prot = fs->first_prot; |
| 950 | fs->object = fs->first_object; |
| 951 | pindex = first_pindex; |
| 952 | |
| 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, |
| 959 | * fs->prot above will simply not have VM_PROT_WRITE set. |
| 960 | * |
| 961 | * (2) If the mapping is a virtual page table we need to be able |
| 962 | * to detect writes so we can set VPTE_M in the virtual page |
| 963 | * table. |
| 964 | * |
| 965 | * (3) If the VM page is read-only or copy-on-write, upgrading would |
| 966 | * just result in an unnecessary COW fault. |
| 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. |
| 971 | */ |
| 972 | if (fs->entry->maptype == VM_MAPTYPE_VPAGETABLE) { |
| 973 | if ((fault_type & VM_PROT_WRITE) == 0) |
| 974 | fs->prot &= ~VM_PROT_WRITE; |
| 975 | } |
| 976 | |
| 977 | lwkt_gettoken(&vm_token); |
| 978 | |
| 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); |
| 985 | lwkt_reltoken(&vm_token); |
| 986 | return (KERN_PROTECTION_FAILURE); |
| 987 | } |
| 988 | |
| 989 | /* |
| 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. |
| 994 | */ |
| 995 | crit_enter(); |
| 996 | fs->m = vm_page_lookup(fs->object, pindex); |
| 997 | if (fs->m != NULL) { |
| 998 | int queue; |
| 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 | */ |
| 1015 | if ((fs->m->flags & PG_BUSY) || fs->m->busy) { |
| 1016 | unlock_things(fs); |
| 1017 | vm_page_sleep_busy(fs->m, TRUE, "vmpfw"); |
| 1018 | mycpu->gd_cnt.v_intrans++; |
| 1019 | vm_object_deallocate(fs->first_object); |
| 1020 | fs->first_object = NULL; |
| 1021 | lwkt_reltoken(&vm_token); |
| 1022 | crit_exit(); |
| 1023 | return (KERN_TRY_AGAIN); |
| 1024 | } |
| 1025 | |
| 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); |
| 1032 | |
| 1033 | if ((queue - fs->m->pc) == PQ_CACHE && |
| 1034 | vm_page_count_severe()) { |
| 1035 | vm_page_activate(fs->m); |
| 1036 | unlock_and_deallocate(fs); |
| 1037 | vm_waitpfault(); |
| 1038 | lwkt_reltoken(&vm_token); |
| 1039 | crit_exit(); |
| 1040 | return (KERN_TRY_AGAIN); |
| 1041 | } |
| 1042 | |
| 1043 | /* |
| 1044 | * Mark page busy for other processes, and the |
| 1045 | * pagedaemon. If it still isn't completely valid |
| 1046 | * (readable), or if a read-ahead-mark is set on |
| 1047 | * the VM page, jump to readrest, else we found the |
| 1048 | * page and can return. |
| 1049 | * |
| 1050 | * We can release the spl once we have marked the |
| 1051 | * page busy. |
| 1052 | */ |
| 1053 | vm_page_busy(fs->m); |
| 1054 | crit_exit(); |
| 1055 | |
| 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 | } |
| 1067 | } |
| 1068 | break; /* break to PAGE HAS BEEN FOUND */ |
| 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. |
| 1074 | * |
| 1075 | * NOTE: We are still in a critical section. |
| 1076 | */ |
| 1077 | if (TRYPAGER(fs) || fs->object == fs->first_object) { |
| 1078 | /* |
| 1079 | * If the page is beyond the object size we fail |
| 1080 | */ |
| 1081 | if (pindex >= fs->object->size) { |
| 1082 | lwkt_reltoken(&vm_token); |
| 1083 | crit_exit(); |
| 1084 | unlock_and_deallocate(fs); |
| 1085 | return (KERN_PROTECTION_FAILURE); |
| 1086 | } |
| 1087 | |
| 1088 | /* |
| 1089 | * Ratelimit. |
| 1090 | */ |
| 1091 | if (fs->didlimit == 0 && curproc != NULL) { |
| 1092 | int limticks; |
| 1093 | |
| 1094 | limticks = vm_fault_ratelimit(curproc->p_vmspace); |
| 1095 | if (limticks) { |
| 1096 | lwkt_reltoken(&vm_token); |
| 1097 | crit_exit(); |
| 1098 | unlock_and_deallocate(fs); |
| 1099 | tsleep(curproc, 0, "vmrate", limticks); |
| 1100 | fs->didlimit = 1; |
| 1101 | return (KERN_TRY_AGAIN); |
| 1102 | } |
| 1103 | } |
| 1104 | |
| 1105 | /* |
| 1106 | * Allocate a new page for this object/offset pair. |
| 1107 | */ |
| 1108 | fs->m = NULL; |
| 1109 | if (!vm_page_count_severe()) { |
| 1110 | fs->m = vm_page_alloc(fs->object, pindex, |
| 1111 | (fs->vp || fs->object->backing_object) ? VM_ALLOC_NORMAL : VM_ALLOC_NORMAL | VM_ALLOC_ZERO); |
| 1112 | } |
| 1113 | if (fs->m == NULL) { |
| 1114 | lwkt_reltoken(&vm_token); |
| 1115 | crit_exit(); |
| 1116 | unlock_and_deallocate(fs); |
| 1117 | vm_waitpfault(); |
| 1118 | return (KERN_TRY_AGAIN); |
| 1119 | } |
| 1120 | } |
| 1121 | crit_exit(); |
| 1122 | |
| 1123 | readrest: |
| 1124 | /* |
| 1125 | * We have found an invalid or partially valid page, a |
| 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. |
| 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. |
| 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. |
| 1136 | */ |
| 1137 | if (TRYPAGER(fs)) { |
| 1138 | int rv; |
| 1139 | int seqaccess; |
| 1140 | u_char behavior = vm_map_entry_behavior(fs->entry); |
| 1141 | |
| 1142 | if (behavior == MAP_ENTRY_BEHAV_RANDOM) |
| 1143 | seqaccess = 0; |
| 1144 | else |
| 1145 | seqaccess = -1; |
| 1146 | |
| 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 | */ |
| 1160 | if ((fs->first_object->type != OBJT_DEVICE) && |
| 1161 | (behavior == MAP_ENTRY_BEHAV_SEQUENTIAL || |
| 1162 | (behavior != MAP_ENTRY_BEHAV_RANDOM && |
| 1163 | (fs->m->flags & PG_RAM))) |
| 1164 | ) { |
| 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 | } |
| 1178 | |
| 1179 | crit_enter(); |
| 1180 | while (scan_count) { |
| 1181 | vm_page_t mt; |
| 1182 | |
| 1183 | mt = vm_page_lookup(fs->first_object, |
| 1184 | scan_pindex); |
| 1185 | if (mt == NULL || |
| 1186 | (mt->valid != VM_PAGE_BITS_ALL)) { |
| 1187 | break; |
| 1188 | } |
| 1189 | if (mt->busy || |
| 1190 | (mt->flags & (PG_BUSY | PG_FICTITIOUS | PG_UNMANAGED)) || |
| 1191 | mt->hold_count || |
| 1192 | mt->wire_count) { |
| 1193 | goto skip; |
| 1194 | } |
| 1195 | if (mt->dirty == 0) |
| 1196 | vm_page_test_dirty(mt); |
| 1197 | if (mt->dirty) { |
| 1198 | vm_page_busy(mt); |
| 1199 | vm_page_protect(mt, |
| 1200 | VM_PROT_NONE); |
| 1201 | vm_page_deactivate(mt); |
| 1202 | vm_page_wakeup(mt); |
| 1203 | } else { |
| 1204 | vm_page_cache(mt); |
| 1205 | } |
| 1206 | skip: |
| 1207 | --scan_count; |
| 1208 | --scan_pindex; |
| 1209 | } |
| 1210 | crit_exit(); |
| 1211 | |
| 1212 | seqaccess = 1; |
| 1213 | } |
| 1214 | |
| 1215 | /* |
| 1216 | * Avoid deadlocking against the map when doing I/O. |
| 1217 | * fs.object and the page is PG_BUSY'd. |
| 1218 | */ |
| 1219 | unlock_map(fs); |
| 1220 | |
| 1221 | /* |
| 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. |
| 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. |
| 1238 | */ |
| 1239 | rv = vm_pager_get_page(fs->object, &fs->m, seqaccess); |
| 1240 | |
| 1241 | if (rv == VM_PAGER_OK) { |
| 1242 | /* |
| 1243 | * Relookup in case pager changed page. Pager |
| 1244 | * is responsible for disposition of old page |
| 1245 | * if moved. |
| 1246 | * |
| 1247 | * XXX other code segments do relookups too. |
| 1248 | * It's a bad abstraction that needs to be |
| 1249 | * fixed/removed. |
| 1250 | */ |
| 1251 | fs->m = vm_page_lookup(fs->object, pindex); |
| 1252 | if (fs->m == NULL) { |
| 1253 | lwkt_reltoken(&vm_token); |
| 1254 | unlock_and_deallocate(fs); |
| 1255 | return (KERN_TRY_AGAIN); |
| 1256 | } |
| 1257 | |
| 1258 | ++fs->hardfault; |
| 1259 | break; /* break to PAGE HAS BEEN FOUND */ |
| 1260 | } |
| 1261 | |
| 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 | */ |
| 1275 | if (rv == VM_PAGER_ERROR) { |
| 1276 | if (curproc) |
| 1277 | kprintf("vm_fault: pager read error, pid %d (%s)\n", curproc->p_pid, curproc->p_comm); |
| 1278 | else |
| 1279 | kprintf("vm_fault: pager read error, thread %p (%s)\n", curthread, curproc->p_comm); |
| 1280 | } |
| 1281 | |
| 1282 | /* |
| 1283 | * Data outside the range of the pager or an I/O error |
| 1284 | * |
| 1285 | * The page may have been wired during the pagein, |
| 1286 | * e.g. by the buffer cache, and cannot simply be |
| 1287 | * freed. Call vnode_pager_freepage() to deal with it. |
| 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 | */ |
| 1294 | if (((fs->map != &kernel_map) && |
| 1295 | (rv == VM_PAGER_ERROR)) || (rv == VM_PAGER_BAD)) { |
| 1296 | vnode_pager_freepage(fs->m); |
| 1297 | lwkt_reltoken(&vm_token); |
| 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 */ |
| 1305 | } |
| 1306 | if (fs->object != fs->first_object) { |
| 1307 | vnode_pager_freepage(fs->m); |
| 1308 | fs->m = NULL; |
| 1309 | /* |
| 1310 | * XXX - we cannot just fall out at this |
| 1311 | * point, m has been freed and is invalid! |
| 1312 | */ |
| 1313 | } |
| 1314 | } |
| 1315 | |
| 1316 | /* |
| 1317 | * We get here if the object has a default pager (or unwiring) |
| 1318 | * or the pager doesn't have the page. |
| 1319 | */ |
| 1320 | if (fs->object == fs->first_object) |
| 1321 | fs->first_m = fs->m; |
| 1322 | |
| 1323 | /* |
| 1324 | * Move on to the next object. Lock the next object before |
| 1325 | * unlocking the current one. |
| 1326 | */ |
| 1327 | pindex += OFF_TO_IDX(fs->object->backing_object_offset); |
| 1328 | next_object = fs->object->backing_object; |
| 1329 | if (next_object == NULL) { |
| 1330 | /* |
| 1331 | * If there's no object left, fill the page in the top |
| 1332 | * object with zeros. |
| 1333 | */ |
| 1334 | if (fs->object != fs->first_object) { |
| 1335 | vm_object_pip_wakeup(fs->object); |
| 1336 | |
| 1337 | fs->object = fs->first_object; |
| 1338 | pindex = first_pindex; |
| 1339 | fs->m = fs->first_m; |
| 1340 | } |
| 1341 | fs->first_m = NULL; |
| 1342 | |
| 1343 | /* |
| 1344 | * Zero the page if necessary and mark it valid. |
| 1345 | */ |
| 1346 | if ((fs->m->flags & PG_ZERO) == 0) { |
| 1347 | vm_page_zero_fill(fs->m); |
| 1348 | } else { |
| 1349 | mycpu->gd_cnt.v_ozfod++; |
| 1350 | } |
| 1351 | mycpu->gd_cnt.v_zfod++; |
| 1352 | fs->m->valid = VM_PAGE_BITS_ALL; |
| 1353 | break; /* break to PAGE HAS BEEN FOUND */ |
| 1354 | } |
| 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); |
| 1362 | } |
| 1363 | |
| 1364 | /* |
| 1365 | * PAGE HAS BEEN FOUND. [Loop invariant still holds -- the object lock |
| 1366 | * is held.] |
| 1367 | * |
| 1368 | * vm_token is still held |
| 1369 | * |
| 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 | */ |
| 1374 | KASSERT((fs->m->flags & PG_BUSY) != 0, |
| 1375 | ("vm_fault: not busy after main loop")); |
| 1376 | |
| 1377 | if (fs->object != fs->first_object) { |
| 1378 | /* |
| 1379 | * We only really need to copy if we want to write it. |
| 1380 | */ |
| 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 | */ |
| 1392 | if ( |
| 1393 | /* |
| 1394 | * Map, if present, has not changed |
| 1395 | */ |
| 1396 | (fs->map == NULL || |
| 1397 | fs->map_generation == fs->map->timestamp) && |
| 1398 | /* |
| 1399 | * Only one shadow object |
| 1400 | */ |
| 1401 | (fs->object->shadow_count == 1) && |
| 1402 | /* |
| 1403 | * No COW refs, except us |
| 1404 | */ |
| 1405 | (fs->object->ref_count == 1) && |
| 1406 | /* |
| 1407 | * No one else can look this object up |
| 1408 | */ |
| 1409 | (fs->object->handle == NULL) && |
| 1410 | /* |
| 1411 | * No other ways to look the object up |
| 1412 | */ |
| 1413 | ((fs->object->type == OBJT_DEFAULT) || |
| 1414 | (fs->object->type == OBJT_SWAP)) && |
| 1415 | /* |
| 1416 | * We don't chase down the shadow chain |
| 1417 | */ |
| 1418 | (fs->object == fs->first_object->backing_object) && |
| 1419 | |
| 1420 | /* |
| 1421 | * grab the lock if we need to |
| 1422 | */ |
| 1423 | (fs->lookup_still_valid || |
| 1424 | fs->map == NULL || |
| 1425 | lockmgr(&fs->map->lock, LK_EXCLUSIVE|LK_NOWAIT) == 0) |
| 1426 | ) { |
| 1427 | |
| 1428 | fs->lookup_still_valid = 1; |
| 1429 | /* |
| 1430 | * get rid of the unnecessary page |
| 1431 | */ |
| 1432 | vm_page_protect(fs->first_m, VM_PROT_NONE); |
| 1433 | vm_page_free(fs->first_m); |
| 1434 | fs->first_m = NULL; |
| 1435 | |
| 1436 | /* |
| 1437 | * grab the page and put it into the |
| 1438 | * process'es object. The page is |
| 1439 | * automatically made dirty. |
| 1440 | */ |
| 1441 | vm_page_rename(fs->m, fs->first_object, first_pindex); |
| 1442 | fs->first_m = fs->m; |
| 1443 | vm_page_busy(fs->first_m); |
| 1444 | fs->m = NULL; |
| 1445 | mycpu->gd_cnt.v_cow_optim++; |
| 1446 | } else { |
| 1447 | /* |
| 1448 | * Oh, well, lets copy it. |
| 1449 | */ |
| 1450 | vm_page_copy(fs->m, fs->first_m); |
| 1451 | vm_page_event(fs->m, VMEVENT_COW); |
| 1452 | } |
| 1453 | |
| 1454 | if (fs->m) { |
| 1455 | /* |
| 1456 | * We no longer need the old page or object. |
| 1457 | */ |
| 1458 | release_page(fs); |
| 1459 | } |
| 1460 | |
| 1461 | /* |
| 1462 | * fs->object != fs->first_object due to above |
| 1463 | * conditional |
| 1464 | */ |
| 1465 | vm_object_pip_wakeup(fs->object); |
| 1466 | |
| 1467 | /* |
| 1468 | * Only use the new page below... |
| 1469 | */ |
| 1470 | |
| 1471 | mycpu->gd_cnt.v_cow_faults++; |
| 1472 | fs->m = fs->first_m; |
| 1473 | fs->object = fs->first_object; |
| 1474 | pindex = first_pindex; |
| 1475 | } else { |
| 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; |
| 1481 | } |
| 1482 | } |
| 1483 | |
| 1484 | /* |
| 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. |
| 1489 | */ |
| 1490 | |
| 1491 | if (!fs->lookup_still_valid && |
| 1492 | fs->map != NULL && |
| 1493 | (fs->map->timestamp != fs->map_generation)) { |
| 1494 | release_page(fs); |
| 1495 | lwkt_reltoken(&vm_token); |
| 1496 | unlock_and_deallocate(fs); |
| 1497 | return (KERN_TRY_AGAIN); |
| 1498 | } |
| 1499 | |
| 1500 | /* |
| 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. |
| 1514 | */ |
| 1515 | if (fs->prot & VM_PROT_WRITE) { |
| 1516 | vm_object_set_writeable_dirty(fs->m->object); |
| 1517 | if (fs->entry->eflags & MAP_ENTRY_NOSYNC) { |
| 1518 | if (fs->m->dirty == 0) |
| 1519 | vm_page_flag_set(fs->m, PG_NOSYNC); |
| 1520 | } else { |
| 1521 | vm_page_flag_clear(fs->m, PG_NOSYNC); |
| 1522 | } |
| 1523 | if (fs->fault_flags & VM_FAULT_DIRTY) { |
| 1524 | crit_enter(); |
| 1525 | vm_page_dirty(fs->m); |
| 1526 | swap_pager_unswapped(fs->m); |
| 1527 | crit_exit(); |
| 1528 | } |
| 1529 | } |
| 1530 | |
| 1531 | lwkt_reltoken(&vm_token); |
| 1532 | |
| 1533 | /* |
| 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. |
| 1537 | */ |
| 1538 | KASSERT(fs->m->flags & PG_BUSY, |
| 1539 | ("vm_fault: page %p not busy!", fs->m)); |
| 1540 | |
| 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 | */ |
| 1545 | if (fs->m->valid != VM_PAGE_BITS_ALL) { |
| 1546 | vm_page_zero_invalid(fs->m, TRUE); |
| 1547 | kprintf("Warning: page %p partially invalid on fault\n", fs->m); |
| 1548 | } |
| 1549 | |
| 1550 | return (KERN_SUCCESS); |
| 1551 | } |
| 1552 | |
| 1553 | /* |
| 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. |
| 1559 | * |
| 1560 | * No requirements. |
| 1561 | */ |
| 1562 | int |
| 1563 | vm_fault_wire(vm_map_t map, vm_map_entry_t entry, boolean_t user_wire) |
| 1564 | { |
| 1565 | boolean_t fictitious; |
| 1566 | vm_offset_t start; |
| 1567 | vm_offset_t end; |
| 1568 | vm_offset_t va; |
| 1569 | vm_paddr_t pa; |
| 1570 | pmap_t pmap; |
| 1571 | int rv; |
| 1572 | |
| 1573 | pmap = vm_map_pmap(map); |
| 1574 | start = entry->start; |
| 1575 | end = entry->end; |
| 1576 | fictitious = entry->object.vm_object && |
| 1577 | (entry->object.vm_object->type == OBJT_DEVICE); |
| 1578 | |
| 1579 | lwkt_gettoken(&vm_token); |
| 1580 | vm_map_unlock(map); |
| 1581 | map->timestamp++; |
| 1582 | |
| 1583 | /* |
| 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) { |
| 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 | } |
| 1595 | if (rv) { |
| 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 | } |
| 1604 | vm_map_lock(map); |
| 1605 | lwkt_reltoken(&vm_token); |
| 1606 | return (rv); |
| 1607 | } |
| 1608 | } |
| 1609 | vm_map_lock(map); |
| 1610 | lwkt_reltoken(&vm_token); |
| 1611 | return (KERN_SUCCESS); |
| 1612 | } |
| 1613 | |
| 1614 | /* |
| 1615 | * Unwire a range of virtual addresses in a map. The map should be |
| 1616 | * locked. |
| 1617 | */ |
| 1618 | void |
| 1619 | vm_fault_unwire(vm_map_t map, vm_map_entry_t entry) |
| 1620 | { |
| 1621 | boolean_t fictitious; |
| 1622 | vm_offset_t start; |
| 1623 | vm_offset_t end; |
| 1624 | vm_offset_t va; |
| 1625 | vm_paddr_t pa; |
| 1626 | pmap_t pmap; |
| 1627 | |
| 1628 | pmap = vm_map_pmap(map); |
| 1629 | start = entry->start; |
| 1630 | end = entry->end; |
| 1631 | fictitious = entry->object.vm_object && |
| 1632 | (entry->object.vm_object->type == OBJT_DEVICE); |
| 1633 | |
| 1634 | /* |
| 1635 | * Since the pages are wired down, we must be able to get their |
| 1636 | * mappings from the physical map system. |
| 1637 | */ |
| 1638 | lwkt_gettoken(&vm_token); |
| 1639 | for (va = start; va < end; va += PAGE_SIZE) { |
| 1640 | pa = pmap_extract(pmap, va); |
| 1641 | if (pa != 0) { |
| 1642 | pmap_change_wiring(pmap, va, FALSE); |
| 1643 | if (!fictitious) |
| 1644 | vm_page_unwire(PHYS_TO_VM_PAGE(pa), 1); |
| 1645 | } |
| 1646 | } |
| 1647 | lwkt_reltoken(&vm_token); |
| 1648 | } |
| 1649 | |
| 1650 | /* |
| 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 | */ |
| 1663 | static int |
| 1664 | vm_fault_ratelimit(struct vmspace *vmspace) |
| 1665 | { |
| 1666 | if (vm_load_enable == 0) |
| 1667 | return(0); |
| 1668 | if (vmspace->vm_pagesupply > 0) { |
| 1669 | --vmspace->vm_pagesupply; /* SMP race ok */ |
| 1670 | return(0); |
| 1671 | } |
| 1672 | #ifdef INVARIANTS |
| 1673 | if (vm_load_debug) { |
| 1674 | kprintf("load %-4d give %d pgs, wait %d, pid %-5d (%s)\n", |
| 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 | /* |
| 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). |
| 1690 | * |
| 1691 | * No other requirements. |
| 1692 | */ |
| 1693 | void |
| 1694 | vm_fault_copy_entry(vm_map_t dst_map, vm_map_t src_map, |
| 1695 | vm_map_entry_t dst_entry, vm_map_entry_t src_entry) |
| 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 | */ |
| 1717 | vm_map_entry_allocate_object(dst_entry); |
| 1718 | dst_object = dst_entry->object.vm_object; |
| 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) { |
| 1738 | vm_wait(0); |
| 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); |
| 1753 | vm_page_event(src_m, VMEVENT_COW); |
| 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); |
| 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 | |
| 1770 | #if 0 |
| 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 | */ |
| 1786 | static int |
| 1787 | vm_fault_additional_pages(vm_page_t m, int rbehind, int rahead, |
| 1788 | vm_page_t *marray, int *reqpage) |
| 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 | */ |
| 1811 | if (!vm_pager_has_page(object, pindex, &cbehind, &cahead)) { |
| 1812 | *reqpage = 0; /* not used by caller, fix compiler warn */ |
| 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 | /* |
| 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. |
| 1835 | */ |
| 1836 | if (burst_fault == 0 || vm_page_count_severe()) { |
| 1837 | marray[0] = m; |
| 1838 | *reqpage = 0; |
| 1839 | return 1; |
| 1840 | } |
| 1841 | |
| 1842 | /* |
| 1843 | * scan backward for the read behind pages -- in memory |
| 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. |
| 1848 | */ |
| 1849 | if (pindex > 0) { |
| 1850 | if (rbehind > pindex) { |
| 1851 | rbehind = pindex; |
| 1852 | startpindex = 0; |
| 1853 | } else { |
| 1854 | startpindex = pindex - rbehind; |
| 1855 | } |
| 1856 | |
| 1857 | crit_enter(); |
| 1858 | lwkt_gettoken(&vm_token); |
| 1859 | for (tpindex = pindex; tpindex > startpindex; --tpindex) { |
| 1860 | if (vm_page_lookup(object, tpindex - 1)) |
| 1861 | break; |
| 1862 | } |
| 1863 | |
| 1864 | i = 0; |
| 1865 | while (tpindex < pindex) { |
| 1866 | rtm = vm_page_alloc(object, tpindex, VM_ALLOC_SYSTEM); |
| 1867 | if (rtm == NULL) { |
| 1868 | lwkt_reltoken(&vm_token); |
| 1869 | crit_exit(); |
| 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 | } |
| 1877 | marray[i] = rtm; |
| 1878 | ++i; |
| 1879 | ++tpindex; |
| 1880 | } |
| 1881 | lwkt_reltoken(&vm_token); |
| 1882 | crit_exit(); |
| 1883 | } else { |
| 1884 | i = 0; |
| 1885 | } |
| 1886 | |
| 1887 | /* |
| 1888 | * Assign requested page |
| 1889 | */ |
| 1890 | marray[i] = m; |
| 1891 | *reqpage = i; |
| 1892 | ++i; |
| 1893 | |
| 1894 | /* |
| 1895 | * Scan forwards for read-ahead pages |
| 1896 | */ |
| 1897 | tpindex = pindex + 1; |
| 1898 | endpindex = tpindex + rahead; |
| 1899 | if (endpindex > object->size) |
| 1900 | endpindex = object->size; |
| 1901 | |
| 1902 | crit_enter(); |
| 1903 | lwkt_gettoken(&vm_token); |
| 1904 | while (tpindex < endpindex) { |
| 1905 | if (vm_page_lookup(object, tpindex)) |
| 1906 | break; |
| 1907 | rtm = vm_page_alloc(object, tpindex, VM_ALLOC_SYSTEM); |
| 1908 | if (rtm == NULL) |
| 1909 | break; |
| 1910 | marray[i] = rtm; |
| 1911 | ++i; |
| 1912 | ++tpindex; |
| 1913 | } |
| 1914 | lwkt_reltoken(&vm_token); |
| 1915 | crit_exit(); |
| 1916 | |
| 1917 | return (i); |
| 1918 | } |
| 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. |
| 1945 | * |
| 1946 | * No other requirements. |
| 1947 | */ |
| 1948 | #define PFBAK 4 |
| 1949 | #define PFFOR 4 |
| 1950 | #define PAGEORDER_SIZE (PFBAK+PFFOR) |
| 1951 | |
| 1952 | static 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 | |
| 1959 | static void |
| 1960 | vm_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(); |
| 1996 | lwkt_gettoken(&vm_token); |
| 1997 | for (i = 0; i < PAGEORDER_SIZE; i++) { |
| 1998 | vm_object_t lobject; |
| 1999 | int allocated = 0; |
| 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. |
| 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. |
| 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 | } |
| 2040 | /* note: allocate from base object */ |
| 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; |
| 2052 | allocated = 1; |
| 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 | /* |
| 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). |
| 2093 | */ |
| 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) && |
| 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 | } |
| 2110 | lwkt_reltoken(&vm_token); |
| 2111 | crit_exit(); |
| 2112 | } |