| 1 | /* $NetBSD: uvm_amap.c,v 1.107 2012/04/08 20:47:10 chs Exp $ */ |
| 2 | |
| 3 | /* |
| 4 | * Copyright (c) 1997 Charles D. Cranor and Washington University. |
| 5 | * All rights reserved. |
| 6 | * |
| 7 | * Redistribution and use in source and binary forms, with or without |
| 8 | * modification, are permitted provided that the following conditions |
| 9 | * are met: |
| 10 | * 1. Redistributions of source code must retain the above copyright |
| 11 | * notice, this list of conditions and the following disclaimer. |
| 12 | * 2. Redistributions in binary form must reproduce the above copyright |
| 13 | * notice, this list of conditions and the following disclaimer in the |
| 14 | * documentation and/or other materials provided with the distribution. |
| 15 | * |
| 16 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR |
| 17 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
| 18 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. |
| 19 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, |
| 20 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
| 21 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| 22 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| 23 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| 24 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF |
| 25 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| 26 | */ |
| 27 | |
| 28 | /* |
| 29 | * uvm_amap.c: amap operations |
| 30 | */ |
| 31 | |
| 32 | /* |
| 33 | * this file contains functions that perform operations on amaps. see |
| 34 | * uvm_amap.h for a brief explanation of the role of amaps in uvm. |
| 35 | */ |
| 36 | |
| 37 | #include <sys/cdefs.h> |
| 38 | __KERNEL_RCSID(0, "$NetBSD: uvm_amap.c,v 1.107 2012/04/08 20:47:10 chs Exp $" ); |
| 39 | |
| 40 | #include "opt_uvmhist.h" |
| 41 | |
| 42 | #include <sys/param.h> |
| 43 | #include <sys/systm.h> |
| 44 | #include <sys/kernel.h> |
| 45 | #include <sys/kmem.h> |
| 46 | #include <sys/pool.h> |
| 47 | #include <sys/atomic.h> |
| 48 | |
| 49 | #include <uvm/uvm.h> |
| 50 | #include <uvm/uvm_swap.h> |
| 51 | |
| 52 | /* |
| 53 | * cache for allocation of vm_map structures. note that in order to |
| 54 | * avoid an endless loop, the amap cache's allocator cannot allocate |
| 55 | * memory from an amap (it currently goes through the kernel uobj, so |
| 56 | * we are ok). |
| 57 | */ |
| 58 | static struct pool_cache uvm_amap_cache; |
| 59 | static kmutex_t amap_list_lock; |
| 60 | static LIST_HEAD(, vm_amap) amap_list; |
| 61 | |
| 62 | /* |
| 63 | * local functions |
| 64 | */ |
| 65 | |
| 66 | static inline void |
| 67 | amap_list_insert(struct vm_amap *amap) |
| 68 | { |
| 69 | |
| 70 | mutex_enter(&amap_list_lock); |
| 71 | LIST_INSERT_HEAD(&amap_list, amap, am_list); |
| 72 | mutex_exit(&amap_list_lock); |
| 73 | } |
| 74 | |
| 75 | static inline void |
| 76 | amap_list_remove(struct vm_amap *amap) |
| 77 | { |
| 78 | |
| 79 | mutex_enter(&amap_list_lock); |
| 80 | LIST_REMOVE(amap, am_list); |
| 81 | mutex_exit(&amap_list_lock); |
| 82 | } |
| 83 | |
| 84 | static int |
| 85 | amap_roundup_slots(int slots) |
| 86 | { |
| 87 | |
| 88 | return kmem_roundup_size(slots * sizeof(int)) / sizeof(int); |
| 89 | } |
| 90 | |
| 91 | #ifdef UVM_AMAP_PPREF |
| 92 | /* |
| 93 | * what is ppref? ppref is an _optional_ amap feature which is used |
| 94 | * to keep track of reference counts on a per-page basis. it is enabled |
| 95 | * when UVM_AMAP_PPREF is defined. |
| 96 | * |
| 97 | * when enabled, an array of ints is allocated for the pprefs. this |
| 98 | * array is allocated only when a partial reference is added to the |
| 99 | * map (either by unmapping part of the amap, or gaining a reference |
| 100 | * to only a part of an amap). if the allocation of the array fails |
| 101 | * (KM_NOSLEEP), then we set the array pointer to PPREF_NONE to indicate |
| 102 | * that we tried to do ppref's but couldn't alloc the array so just |
| 103 | * give up (after all, this is an optional feature!). |
| 104 | * |
| 105 | * the array is divided into page sized "chunks." for chunks of length 1, |
| 106 | * the chunk reference count plus one is stored in that chunk's slot. |
| 107 | * for chunks of length > 1 the first slot contains (the reference count |
| 108 | * plus one) * -1. [the negative value indicates that the length is |
| 109 | * greater than one.] the second slot of the chunk contains the length |
| 110 | * of the chunk. here is an example: |
| 111 | * |
| 112 | * actual REFS: 2 2 2 2 3 1 1 0 0 0 4 4 0 1 1 1 |
| 113 | * ppref: -3 4 x x 4 -2 2 -1 3 x -5 2 1 -2 3 x |
| 114 | * <----------><-><----><-------><----><-><-------> |
| 115 | * (x = don't care) |
| 116 | * |
| 117 | * this allows us to allow one int to contain the ref count for the whole |
| 118 | * chunk. note that the "plus one" part is needed because a reference |
| 119 | * count of zero is neither positive or negative (need a way to tell |
| 120 | * if we've got one zero or a bunch of them). |
| 121 | * |
| 122 | * here are some in-line functions to help us. |
| 123 | */ |
| 124 | |
| 125 | /* |
| 126 | * pp_getreflen: get the reference and length for a specific offset |
| 127 | * |
| 128 | * => ppref's amap must be locked |
| 129 | */ |
| 130 | static inline void |
| 131 | pp_getreflen(int *ppref, int offset, int *refp, int *lenp) |
| 132 | { |
| 133 | |
| 134 | if (ppref[offset] > 0) { /* chunk size must be 1 */ |
| 135 | *refp = ppref[offset] - 1; /* don't forget to adjust */ |
| 136 | *lenp = 1; |
| 137 | } else { |
| 138 | *refp = (ppref[offset] * -1) - 1; |
| 139 | *lenp = ppref[offset+1]; |
| 140 | } |
| 141 | } |
| 142 | |
| 143 | /* |
| 144 | * pp_setreflen: set the reference and length for a specific offset |
| 145 | * |
| 146 | * => ppref's amap must be locked |
| 147 | */ |
| 148 | static inline void |
| 149 | pp_setreflen(int *ppref, int offset, int ref, int len) |
| 150 | { |
| 151 | if (len == 0) |
| 152 | return; |
| 153 | if (len == 1) { |
| 154 | ppref[offset] = ref + 1; |
| 155 | } else { |
| 156 | ppref[offset] = (ref + 1) * -1; |
| 157 | ppref[offset+1] = len; |
| 158 | } |
| 159 | } |
| 160 | #endif /* UVM_AMAP_PPREF */ |
| 161 | |
| 162 | /* |
| 163 | * amap_alloc1: allocate an amap, but do not initialise the overlay. |
| 164 | * |
| 165 | * => Note: lock is not set. |
| 166 | */ |
| 167 | static struct vm_amap * |
| 168 | amap_alloc1(int slots, int padslots, int flags) |
| 169 | { |
| 170 | const bool nowait = (flags & UVM_FLAG_NOWAIT) != 0; |
| 171 | const km_flag_t kmflags = nowait ? KM_NOSLEEP : KM_SLEEP; |
| 172 | struct vm_amap *amap; |
| 173 | int totalslots; |
| 174 | |
| 175 | amap = pool_cache_get(&uvm_amap_cache, nowait ? PR_NOWAIT : PR_WAITOK); |
| 176 | if (amap == NULL) { |
| 177 | return NULL; |
| 178 | } |
| 179 | totalslots = amap_roundup_slots(slots + padslots); |
| 180 | amap->am_lock = NULL; |
| 181 | amap->am_ref = 1; |
| 182 | amap->am_flags = 0; |
| 183 | #ifdef UVM_AMAP_PPREF |
| 184 | amap->am_ppref = NULL; |
| 185 | #endif |
| 186 | amap->am_maxslot = totalslots; |
| 187 | amap->am_nslot = slots; |
| 188 | amap->am_nused = 0; |
| 189 | |
| 190 | /* |
| 191 | * Note: since allocations are likely big, we expect to reduce the |
| 192 | * memory fragmentation by allocating them in separate blocks. |
| 193 | */ |
| 194 | amap->am_slots = kmem_alloc(totalslots * sizeof(int), kmflags); |
| 195 | if (amap->am_slots == NULL) |
| 196 | goto fail1; |
| 197 | |
| 198 | amap->am_bckptr = kmem_alloc(totalslots * sizeof(int), kmflags); |
| 199 | if (amap->am_bckptr == NULL) |
| 200 | goto fail2; |
| 201 | |
| 202 | amap->am_anon = kmem_alloc(totalslots * sizeof(struct vm_anon *), |
| 203 | kmflags); |
| 204 | if (amap->am_anon == NULL) |
| 205 | goto fail3; |
| 206 | |
| 207 | return amap; |
| 208 | |
| 209 | fail3: |
| 210 | kmem_free(amap->am_bckptr, totalslots * sizeof(int)); |
| 211 | fail2: |
| 212 | kmem_free(amap->am_slots, totalslots * sizeof(int)); |
| 213 | fail1: |
| 214 | pool_cache_put(&uvm_amap_cache, amap); |
| 215 | |
| 216 | /* |
| 217 | * XXX hack to tell the pagedaemon how many pages we need, |
| 218 | * since we can need more than it would normally free. |
| 219 | */ |
| 220 | if (nowait) { |
| 221 | extern u_int ; |
| 222 | atomic_add_int(&uvm_extrapages, |
| 223 | ((sizeof(int) * 2 + sizeof(struct vm_anon *)) * |
| 224 | totalslots) >> PAGE_SHIFT); |
| 225 | } |
| 226 | return NULL; |
| 227 | } |
| 228 | |
| 229 | /* |
| 230 | * amap_alloc: allocate an amap to manage "sz" bytes of anonymous VM |
| 231 | * |
| 232 | * => caller should ensure sz is a multiple of PAGE_SIZE |
| 233 | * => reference count to new amap is set to one |
| 234 | * => new amap is returned unlocked |
| 235 | */ |
| 236 | |
| 237 | struct vm_amap * |
| 238 | amap_alloc(vaddr_t sz, vaddr_t padsz, int waitf) |
| 239 | { |
| 240 | struct vm_amap *amap; |
| 241 | int slots, padslots; |
| 242 | UVMHIST_FUNC("amap_alloc" ); UVMHIST_CALLED(maphist); |
| 243 | |
| 244 | AMAP_B2SLOT(slots, sz); |
| 245 | AMAP_B2SLOT(padslots, padsz); |
| 246 | |
| 247 | amap = amap_alloc1(slots, padslots, waitf); |
| 248 | if (amap) { |
| 249 | memset(amap->am_anon, 0, |
| 250 | amap->am_maxslot * sizeof(struct vm_anon *)); |
| 251 | amap->am_lock = mutex_obj_alloc(MUTEX_DEFAULT, IPL_NONE); |
| 252 | amap_list_insert(amap); |
| 253 | } |
| 254 | |
| 255 | UVMHIST_LOG(maphist,"<- done, amap = 0x%x, sz=%d" , amap, sz, 0, 0); |
| 256 | return(amap); |
| 257 | } |
| 258 | |
| 259 | /* |
| 260 | * uvm_amap_init: initialize the amap system. |
| 261 | */ |
| 262 | void |
| 263 | uvm_amap_init(void) |
| 264 | { |
| 265 | |
| 266 | mutex_init(&amap_list_lock, MUTEX_DEFAULT, IPL_NONE); |
| 267 | |
| 268 | pool_cache_bootstrap(&uvm_amap_cache, sizeof(struct vm_amap), 0, 0, 0, |
| 269 | "amappl" , NULL, IPL_NONE, NULL, NULL, NULL); |
| 270 | } |
| 271 | |
| 272 | /* |
| 273 | * amap_free: free an amap |
| 274 | * |
| 275 | * => the amap must be unlocked |
| 276 | * => the amap should have a zero reference count and be empty |
| 277 | */ |
| 278 | void |
| 279 | amap_free(struct vm_amap *amap) |
| 280 | { |
| 281 | int slots; |
| 282 | |
| 283 | UVMHIST_FUNC("amap_free" ); UVMHIST_CALLED(maphist); |
| 284 | |
| 285 | KASSERT(amap->am_ref == 0 && amap->am_nused == 0); |
| 286 | KASSERT((amap->am_flags & AMAP_SWAPOFF) == 0); |
| 287 | if (amap->am_lock != NULL) { |
| 288 | KASSERT(!mutex_owned(amap->am_lock)); |
| 289 | mutex_obj_free(amap->am_lock); |
| 290 | } |
| 291 | slots = amap->am_maxslot; |
| 292 | kmem_free(amap->am_slots, slots * sizeof(*amap->am_slots)); |
| 293 | kmem_free(amap->am_bckptr, slots * sizeof(*amap->am_bckptr)); |
| 294 | kmem_free(amap->am_anon, slots * sizeof(*amap->am_anon)); |
| 295 | #ifdef UVM_AMAP_PPREF |
| 296 | if (amap->am_ppref && amap->am_ppref != PPREF_NONE) |
| 297 | kmem_free(amap->am_ppref, slots * sizeof(*amap->am_ppref)); |
| 298 | #endif |
| 299 | pool_cache_put(&uvm_amap_cache, amap); |
| 300 | UVMHIST_LOG(maphist,"<- done, freed amap = 0x%x" , amap, 0, 0, 0); |
| 301 | } |
| 302 | |
| 303 | /* |
| 304 | * amap_extend: extend the size of an amap (if needed) |
| 305 | * |
| 306 | * => called from uvm_map when we want to extend an amap to cover |
| 307 | * a new mapping (rather than allocate a new one) |
| 308 | * => amap should be unlocked (we will lock it) |
| 309 | * => to safely extend an amap it should have a reference count of |
| 310 | * one (thus it can't be shared) |
| 311 | */ |
| 312 | int |
| 313 | amap_extend(struct vm_map_entry *entry, vsize_t addsize, int flags) |
| 314 | { |
| 315 | struct vm_amap *amap = entry->aref.ar_amap; |
| 316 | int slotoff = entry->aref.ar_pageoff; |
| 317 | int slotmapped, slotadd, slotneed, slotadded, slotalloc; |
| 318 | int slotadj, slotspace; |
| 319 | int oldnslots; |
| 320 | #ifdef UVM_AMAP_PPREF |
| 321 | int *newppref, *oldppref; |
| 322 | #endif |
| 323 | int i, *newsl, *newbck, *oldsl, *oldbck; |
| 324 | struct vm_anon **newover, **oldover, *tofree; |
| 325 | const km_flag_t kmflags = |
| 326 | (flags & AMAP_EXTEND_NOWAIT) ? KM_NOSLEEP : KM_SLEEP; |
| 327 | |
| 328 | UVMHIST_FUNC("amap_extend" ); UVMHIST_CALLED(maphist); |
| 329 | |
| 330 | UVMHIST_LOG(maphist, " (entry=0x%x, addsize=0x%x, flags=0x%x)" , |
| 331 | entry, addsize, flags, 0); |
| 332 | |
| 333 | /* |
| 334 | * first, determine how many slots we need in the amap. don't |
| 335 | * forget that ar_pageoff could be non-zero: this means that |
| 336 | * there are some unused slots before us in the amap. |
| 337 | */ |
| 338 | |
| 339 | amap_lock(amap); |
| 340 | KASSERT(amap_refs(amap) == 1); /* amap can't be shared */ |
| 341 | AMAP_B2SLOT(slotmapped, entry->end - entry->start); /* slots mapped */ |
| 342 | AMAP_B2SLOT(slotadd, addsize); /* slots to add */ |
| 343 | if (flags & AMAP_EXTEND_FORWARDS) { |
| 344 | slotneed = slotoff + slotmapped + slotadd; |
| 345 | slotadj = 0; |
| 346 | slotspace = 0; |
| 347 | } |
| 348 | else { |
| 349 | slotneed = slotadd + slotmapped; |
| 350 | slotadj = slotadd - slotoff; |
| 351 | slotspace = amap->am_maxslot - slotmapped; |
| 352 | } |
| 353 | tofree = NULL; |
| 354 | |
| 355 | /* |
| 356 | * case 1: we already have enough slots in the map and thus |
| 357 | * only need to bump the reference counts on the slots we are |
| 358 | * adding. |
| 359 | */ |
| 360 | |
| 361 | if (flags & AMAP_EXTEND_FORWARDS) { |
| 362 | if (amap->am_nslot >= slotneed) { |
| 363 | #ifdef UVM_AMAP_PPREF |
| 364 | if (amap->am_ppref && amap->am_ppref != PPREF_NONE) { |
| 365 | amap_pp_adjref(amap, slotoff + slotmapped, |
| 366 | slotadd, 1, &tofree); |
| 367 | } |
| 368 | #endif |
| 369 | uvm_anon_freelst(amap, tofree); |
| 370 | UVMHIST_LOG(maphist, |
| 371 | "<- done (case 1f), amap = 0x%x, sltneed=%d" , |
| 372 | amap, slotneed, 0, 0); |
| 373 | return 0; |
| 374 | } |
| 375 | } else { |
| 376 | if (slotadj <= 0) { |
| 377 | slotoff -= slotadd; |
| 378 | entry->aref.ar_pageoff = slotoff; |
| 379 | #ifdef UVM_AMAP_PPREF |
| 380 | if (amap->am_ppref && amap->am_ppref != PPREF_NONE) { |
| 381 | amap_pp_adjref(amap, slotoff, slotadd, 1, |
| 382 | &tofree); |
| 383 | } |
| 384 | #endif |
| 385 | uvm_anon_freelst(amap, tofree); |
| 386 | UVMHIST_LOG(maphist, |
| 387 | "<- done (case 1b), amap = 0x%x, sltneed=%d" , |
| 388 | amap, slotneed, 0, 0); |
| 389 | return 0; |
| 390 | } |
| 391 | } |
| 392 | |
| 393 | /* |
| 394 | * case 2: we pre-allocated slots for use and we just need to |
| 395 | * bump nslot up to take account for these slots. |
| 396 | */ |
| 397 | |
| 398 | if (amap->am_maxslot >= slotneed) { |
| 399 | if (flags & AMAP_EXTEND_FORWARDS) { |
| 400 | #ifdef UVM_AMAP_PPREF |
| 401 | if (amap->am_ppref && amap->am_ppref != PPREF_NONE) { |
| 402 | if ((slotoff + slotmapped) < amap->am_nslot) |
| 403 | amap_pp_adjref(amap, |
| 404 | slotoff + slotmapped, |
| 405 | (amap->am_nslot - |
| 406 | (slotoff + slotmapped)), 1, |
| 407 | &tofree); |
| 408 | pp_setreflen(amap->am_ppref, amap->am_nslot, 1, |
| 409 | slotneed - amap->am_nslot); |
| 410 | } |
| 411 | #endif |
| 412 | amap->am_nslot = slotneed; |
| 413 | uvm_anon_freelst(amap, tofree); |
| 414 | |
| 415 | /* |
| 416 | * no need to zero am_anon since that was done at |
| 417 | * alloc time and we never shrink an allocation. |
| 418 | */ |
| 419 | |
| 420 | UVMHIST_LOG(maphist,"<- done (case 2f), amap = 0x%x, " |
| 421 | "slotneed=%d" , amap, slotneed, 0, 0); |
| 422 | return 0; |
| 423 | } else { |
| 424 | #ifdef UVM_AMAP_PPREF |
| 425 | if (amap->am_ppref && amap->am_ppref != PPREF_NONE) { |
| 426 | /* |
| 427 | * Slide up the ref counts on the pages that |
| 428 | * are actually in use. |
| 429 | */ |
| 430 | memmove(amap->am_ppref + slotspace, |
| 431 | amap->am_ppref + slotoff, |
| 432 | slotmapped * sizeof(int)); |
| 433 | /* |
| 434 | * Mark the (adjusted) gap at the front as |
| 435 | * referenced/not referenced. |
| 436 | */ |
| 437 | pp_setreflen(amap->am_ppref, |
| 438 | 0, 0, slotspace - slotadd); |
| 439 | pp_setreflen(amap->am_ppref, |
| 440 | slotspace - slotadd, 1, slotadd); |
| 441 | } |
| 442 | #endif |
| 443 | |
| 444 | /* |
| 445 | * Slide the anon pointers up and clear out |
| 446 | * the space we just made. |
| 447 | */ |
| 448 | memmove(amap->am_anon + slotspace, |
| 449 | amap->am_anon + slotoff, |
| 450 | slotmapped * sizeof(struct vm_anon*)); |
| 451 | memset(amap->am_anon + slotoff, 0, |
| 452 | (slotspace - slotoff) * sizeof(struct vm_anon *)); |
| 453 | |
| 454 | /* |
| 455 | * Slide the backpointers up, but don't bother |
| 456 | * wiping out the old slots. |
| 457 | */ |
| 458 | memmove(amap->am_bckptr + slotspace, |
| 459 | amap->am_bckptr + slotoff, |
| 460 | slotmapped * sizeof(int)); |
| 461 | |
| 462 | /* |
| 463 | * Adjust all the useful active slot numbers. |
| 464 | */ |
| 465 | for (i = 0; i < amap->am_nused; i++) |
| 466 | amap->am_slots[i] += (slotspace - slotoff); |
| 467 | |
| 468 | /* |
| 469 | * We just filled all the empty space in the |
| 470 | * front of the amap by activating a few new |
| 471 | * slots. |
| 472 | */ |
| 473 | amap->am_nslot = amap->am_maxslot; |
| 474 | entry->aref.ar_pageoff = slotspace - slotadd; |
| 475 | amap_unlock(amap); |
| 476 | |
| 477 | UVMHIST_LOG(maphist,"<- done (case 2b), amap = 0x%x, " |
| 478 | "slotneed=%d" , amap, slotneed, 0, 0); |
| 479 | return 0; |
| 480 | } |
| 481 | } |
| 482 | |
| 483 | /* |
| 484 | * Case 3: we need to allocate a new amap and copy all the amap |
| 485 | * data over from old amap to the new one. Drop the lock before |
| 486 | * performing allocation. |
| 487 | * |
| 488 | * Note: since allocations are likely big, we expect to reduce the |
| 489 | * memory fragmentation by allocating them in separate blocks. |
| 490 | */ |
| 491 | |
| 492 | amap_unlock(amap); |
| 493 | |
| 494 | if (slotneed >= UVM_AMAP_LARGE) { |
| 495 | return E2BIG; |
| 496 | } |
| 497 | |
| 498 | slotalloc = amap_roundup_slots(slotneed); |
| 499 | #ifdef UVM_AMAP_PPREF |
| 500 | newppref = NULL; |
| 501 | if (amap->am_ppref && amap->am_ppref != PPREF_NONE) { |
| 502 | /* Will be handled later if fails. */ |
| 503 | newppref = kmem_alloc(slotalloc * sizeof(*newppref), kmflags); |
| 504 | } |
| 505 | #endif |
| 506 | newsl = kmem_alloc(slotalloc * sizeof(*newsl), kmflags); |
| 507 | newbck = kmem_alloc(slotalloc * sizeof(*newbck), kmflags); |
| 508 | newover = kmem_alloc(slotalloc * sizeof(*newover), kmflags); |
| 509 | if (newsl == NULL || newbck == NULL || newover == NULL) { |
| 510 | #ifdef UVM_AMAP_PPREF |
| 511 | if (newppref != NULL) { |
| 512 | kmem_free(newppref, slotalloc * sizeof(*newppref)); |
| 513 | } |
| 514 | #endif |
| 515 | if (newsl != NULL) { |
| 516 | kmem_free(newsl, slotalloc * sizeof(*newsl)); |
| 517 | } |
| 518 | if (newbck != NULL) { |
| 519 | kmem_free(newbck, slotalloc * sizeof(*newbck)); |
| 520 | } |
| 521 | if (newover != NULL) { |
| 522 | kmem_free(newover, slotalloc * sizeof(*newover)); |
| 523 | } |
| 524 | return ENOMEM; |
| 525 | } |
| 526 | amap_lock(amap); |
| 527 | KASSERT(amap->am_maxslot < slotneed); |
| 528 | |
| 529 | /* |
| 530 | * Copy everything over to new allocated areas. |
| 531 | */ |
| 532 | |
| 533 | slotadded = slotalloc - amap->am_nslot; |
| 534 | if (!(flags & AMAP_EXTEND_FORWARDS)) |
| 535 | slotspace = slotalloc - slotmapped; |
| 536 | |
| 537 | /* do am_slots */ |
| 538 | oldsl = amap->am_slots; |
| 539 | if (flags & AMAP_EXTEND_FORWARDS) |
| 540 | memcpy(newsl, oldsl, sizeof(int) * amap->am_nused); |
| 541 | else |
| 542 | for (i = 0; i < amap->am_nused; i++) |
| 543 | newsl[i] = oldsl[i] + slotspace - slotoff; |
| 544 | amap->am_slots = newsl; |
| 545 | |
| 546 | /* do am_anon */ |
| 547 | oldover = amap->am_anon; |
| 548 | if (flags & AMAP_EXTEND_FORWARDS) { |
| 549 | memcpy(newover, oldover, |
| 550 | sizeof(struct vm_anon *) * amap->am_nslot); |
| 551 | memset(newover + amap->am_nslot, 0, |
| 552 | sizeof(struct vm_anon *) * slotadded); |
| 553 | } else { |
| 554 | memcpy(newover + slotspace, oldover + slotoff, |
| 555 | sizeof(struct vm_anon *) * slotmapped); |
| 556 | memset(newover, 0, |
| 557 | sizeof(struct vm_anon *) * slotspace); |
| 558 | } |
| 559 | amap->am_anon = newover; |
| 560 | |
| 561 | /* do am_bckptr */ |
| 562 | oldbck = amap->am_bckptr; |
| 563 | if (flags & AMAP_EXTEND_FORWARDS) |
| 564 | memcpy(newbck, oldbck, sizeof(int) * amap->am_nslot); |
| 565 | else |
| 566 | memcpy(newbck + slotspace, oldbck + slotoff, |
| 567 | sizeof(int) * slotmapped); |
| 568 | amap->am_bckptr = newbck; |
| 569 | |
| 570 | #ifdef UVM_AMAP_PPREF |
| 571 | /* do ppref */ |
| 572 | oldppref = amap->am_ppref; |
| 573 | if (newppref) { |
| 574 | if (flags & AMAP_EXTEND_FORWARDS) { |
| 575 | memcpy(newppref, oldppref, |
| 576 | sizeof(int) * amap->am_nslot); |
| 577 | memset(newppref + amap->am_nslot, 0, |
| 578 | sizeof(int) * slotadded); |
| 579 | } else { |
| 580 | memcpy(newppref + slotspace, oldppref + slotoff, |
| 581 | sizeof(int) * slotmapped); |
| 582 | } |
| 583 | amap->am_ppref = newppref; |
| 584 | if ((flags & AMAP_EXTEND_FORWARDS) && |
| 585 | (slotoff + slotmapped) < amap->am_nslot) |
| 586 | amap_pp_adjref(amap, slotoff + slotmapped, |
| 587 | (amap->am_nslot - (slotoff + slotmapped)), 1, |
| 588 | &tofree); |
| 589 | if (flags & AMAP_EXTEND_FORWARDS) |
| 590 | pp_setreflen(newppref, amap->am_nslot, 1, |
| 591 | slotneed - amap->am_nslot); |
| 592 | else { |
| 593 | pp_setreflen(newppref, 0, 0, |
| 594 | slotalloc - slotneed); |
| 595 | pp_setreflen(newppref, slotalloc - slotneed, 1, |
| 596 | slotneed - slotmapped); |
| 597 | } |
| 598 | } else { |
| 599 | if (amap->am_ppref) |
| 600 | amap->am_ppref = PPREF_NONE; |
| 601 | } |
| 602 | #endif |
| 603 | |
| 604 | /* update master values */ |
| 605 | if (flags & AMAP_EXTEND_FORWARDS) |
| 606 | amap->am_nslot = slotneed; |
| 607 | else { |
| 608 | entry->aref.ar_pageoff = slotspace - slotadd; |
| 609 | amap->am_nslot = slotalloc; |
| 610 | } |
| 611 | oldnslots = amap->am_maxslot; |
| 612 | amap->am_maxslot = slotalloc; |
| 613 | |
| 614 | uvm_anon_freelst(amap, tofree); |
| 615 | |
| 616 | kmem_free(oldsl, oldnslots * sizeof(*oldsl)); |
| 617 | kmem_free(oldbck, oldnslots * sizeof(*oldbck)); |
| 618 | kmem_free(oldover, oldnslots * sizeof(*oldover)); |
| 619 | #ifdef UVM_AMAP_PPREF |
| 620 | if (oldppref && oldppref != PPREF_NONE) |
| 621 | kmem_free(oldppref, oldnslots * sizeof(*oldppref)); |
| 622 | #endif |
| 623 | UVMHIST_LOG(maphist,"<- done (case 3), amap = 0x%x, slotneed=%d" , |
| 624 | amap, slotneed, 0, 0); |
| 625 | return 0; |
| 626 | } |
| 627 | |
| 628 | /* |
| 629 | * amap_share_protect: change protection of anons in a shared amap |
| 630 | * |
| 631 | * for shared amaps, given the current data structure layout, it is |
| 632 | * not possible for us to directly locate all maps referencing the |
| 633 | * shared anon (to change the protection). in order to protect data |
| 634 | * in shared maps we use pmap_page_protect(). [this is useful for IPC |
| 635 | * mechanisms like map entry passing that may want to write-protect |
| 636 | * all mappings of a shared amap.] we traverse am_anon or am_slots |
| 637 | * depending on the current state of the amap. |
| 638 | * |
| 639 | * => entry's map and amap must be locked by the caller |
| 640 | */ |
| 641 | void |
| 642 | amap_share_protect(struct vm_map_entry *entry, vm_prot_t prot) |
| 643 | { |
| 644 | struct vm_amap *amap = entry->aref.ar_amap; |
| 645 | u_int slots, lcv, slot, stop; |
| 646 | struct vm_anon *anon; |
| 647 | |
| 648 | KASSERT(mutex_owned(amap->am_lock)); |
| 649 | |
| 650 | AMAP_B2SLOT(slots, (entry->end - entry->start)); |
| 651 | stop = entry->aref.ar_pageoff + slots; |
| 652 | |
| 653 | if (slots < amap->am_nused) { |
| 654 | /* |
| 655 | * Cheaper to traverse am_anon. |
| 656 | */ |
| 657 | for (lcv = entry->aref.ar_pageoff ; lcv < stop ; lcv++) { |
| 658 | anon = amap->am_anon[lcv]; |
| 659 | if (anon == NULL) { |
| 660 | continue; |
| 661 | } |
| 662 | if (anon->an_page) { |
| 663 | pmap_page_protect(anon->an_page, prot); |
| 664 | } |
| 665 | } |
| 666 | return; |
| 667 | } |
| 668 | |
| 669 | /* |
| 670 | * Cheaper to traverse am_slots. |
| 671 | */ |
| 672 | for (lcv = 0 ; lcv < amap->am_nused ; lcv++) { |
| 673 | slot = amap->am_slots[lcv]; |
| 674 | if (slot < entry->aref.ar_pageoff || slot >= stop) { |
| 675 | continue; |
| 676 | } |
| 677 | anon = amap->am_anon[slot]; |
| 678 | if (anon->an_page) { |
| 679 | pmap_page_protect(anon->an_page, prot); |
| 680 | } |
| 681 | } |
| 682 | } |
| 683 | |
| 684 | /* |
| 685 | * amap_wipeout: wipeout all anon's in an amap; then free the amap! |
| 686 | * |
| 687 | * => Called from amap_unref(), when reference count drops to zero. |
| 688 | * => amap must be locked. |
| 689 | */ |
| 690 | |
| 691 | void |
| 692 | amap_wipeout(struct vm_amap *amap) |
| 693 | { |
| 694 | struct vm_anon *tofree = NULL; |
| 695 | u_int lcv; |
| 696 | |
| 697 | UVMHIST_FUNC("amap_wipeout" ); UVMHIST_CALLED(maphist); |
| 698 | UVMHIST_LOG(maphist,"(amap=0x%x)" , amap, 0,0,0); |
| 699 | |
| 700 | KASSERT(mutex_owned(amap->am_lock)); |
| 701 | KASSERT(amap->am_ref == 0); |
| 702 | |
| 703 | if (__predict_false(amap->am_flags & AMAP_SWAPOFF)) { |
| 704 | /* |
| 705 | * Note: amap_swap_off() will call us again. |
| 706 | */ |
| 707 | amap_unlock(amap); |
| 708 | return; |
| 709 | } |
| 710 | amap_list_remove(amap); |
| 711 | |
| 712 | for (lcv = 0 ; lcv < amap->am_nused ; lcv++) { |
| 713 | struct vm_anon *anon; |
| 714 | u_int slot; |
| 715 | |
| 716 | slot = amap->am_slots[lcv]; |
| 717 | anon = amap->am_anon[slot]; |
| 718 | KASSERT(anon != NULL && anon->an_ref != 0); |
| 719 | |
| 720 | KASSERT(anon->an_lock == amap->am_lock); |
| 721 | UVMHIST_LOG(maphist," processing anon 0x%x, ref=%d" , anon, |
| 722 | anon->an_ref, 0, 0); |
| 723 | |
| 724 | /* |
| 725 | * Drop the reference. Defer freeing. |
| 726 | */ |
| 727 | |
| 728 | if (--anon->an_ref == 0) { |
| 729 | anon->an_link = tofree; |
| 730 | tofree = anon; |
| 731 | } |
| 732 | if (curlwp->l_cpu->ci_schedstate.spc_flags & SPCF_SHOULDYIELD) { |
| 733 | preempt(); |
| 734 | } |
| 735 | } |
| 736 | |
| 737 | /* |
| 738 | * Finally, destroy the amap. |
| 739 | */ |
| 740 | |
| 741 | amap->am_nused = 0; |
| 742 | uvm_anon_freelst(amap, tofree); |
| 743 | amap_free(amap); |
| 744 | UVMHIST_LOG(maphist,"<- done!" , 0,0,0,0); |
| 745 | } |
| 746 | |
| 747 | /* |
| 748 | * amap_copy: ensure that a map entry's "needs_copy" flag is false |
| 749 | * by copying the amap if necessary. |
| 750 | * |
| 751 | * => an entry with a null amap pointer will get a new (blank) one. |
| 752 | * => the map that the map entry belongs to must be locked by caller. |
| 753 | * => the amap currently attached to "entry" (if any) must be unlocked. |
| 754 | * => if canchunk is true, then we may clip the entry into a chunk |
| 755 | * => "startva" and "endva" are used only if canchunk is true. they are |
| 756 | * used to limit chunking (e.g. if you have a large space that you |
| 757 | * know you are going to need to allocate amaps for, there is no point |
| 758 | * in allowing that to be chunked) |
| 759 | */ |
| 760 | |
| 761 | void |
| 762 | amap_copy(struct vm_map *map, struct vm_map_entry *entry, int flags, |
| 763 | vaddr_t startva, vaddr_t endva) |
| 764 | { |
| 765 | const int waitf = (flags & AMAP_COPY_NOWAIT) ? UVM_FLAG_NOWAIT : 0; |
| 766 | struct vm_amap *amap, *srcamap; |
| 767 | struct vm_anon *tofree; |
| 768 | u_int slots, lcv; |
| 769 | vsize_t len; |
| 770 | |
| 771 | UVMHIST_FUNC("amap_copy" ); UVMHIST_CALLED(maphist); |
| 772 | UVMHIST_LOG(maphist, " (map=%p, entry=%p, flags=%d)" , |
| 773 | map, entry, flags, 0); |
| 774 | |
| 775 | KASSERT(map != kernel_map); /* we use nointr pool */ |
| 776 | |
| 777 | srcamap = entry->aref.ar_amap; |
| 778 | len = entry->end - entry->start; |
| 779 | |
| 780 | /* |
| 781 | * Is there an amap to copy? If not, create one. |
| 782 | */ |
| 783 | |
| 784 | if (srcamap == NULL) { |
| 785 | const bool canchunk = (flags & AMAP_COPY_NOCHUNK) == 0; |
| 786 | |
| 787 | /* |
| 788 | * Check to see if we have a large amap that we can |
| 789 | * chunk. We align startva/endva to chunk-sized |
| 790 | * boundaries and then clip to them. |
| 791 | */ |
| 792 | |
| 793 | if (canchunk && atop(len) >= UVM_AMAP_LARGE) { |
| 794 | vsize_t chunksize; |
| 795 | |
| 796 | /* Convert slots to bytes. */ |
| 797 | chunksize = UVM_AMAP_CHUNK << PAGE_SHIFT; |
| 798 | startva = (startva / chunksize) * chunksize; |
| 799 | endva = roundup(endva, chunksize); |
| 800 | UVMHIST_LOG(maphist, " chunk amap ==> clip 0x%x->0x%x" |
| 801 | "to 0x%x->0x%x" , entry->start, entry->end, startva, |
| 802 | endva); |
| 803 | UVM_MAP_CLIP_START(map, entry, startva); |
| 804 | |
| 805 | /* Watch out for endva wrap-around! */ |
| 806 | if (endva >= startva) { |
| 807 | UVM_MAP_CLIP_END(map, entry, endva); |
| 808 | } |
| 809 | } |
| 810 | |
| 811 | if ((flags & AMAP_COPY_NOMERGE) == 0 && |
| 812 | uvm_mapent_trymerge(map, entry, UVM_MERGE_COPYING)) { |
| 813 | return; |
| 814 | } |
| 815 | |
| 816 | UVMHIST_LOG(maphist, "<- done [creating new amap 0x%x->0x%x]" , |
| 817 | entry->start, entry->end, 0, 0); |
| 818 | |
| 819 | /* |
| 820 | * Allocate an initialised amap and install it. |
| 821 | * Note: we must update the length after clipping. |
| 822 | */ |
| 823 | len = entry->end - entry->start; |
| 824 | entry->aref.ar_pageoff = 0; |
| 825 | entry->aref.ar_amap = amap_alloc(len, 0, waitf); |
| 826 | if (entry->aref.ar_amap != NULL) { |
| 827 | entry->etype &= ~UVM_ET_NEEDSCOPY; |
| 828 | } |
| 829 | return; |
| 830 | } |
| 831 | |
| 832 | /* |
| 833 | * First check and see if we are the only map entry referencing |
| 834 | * he amap we currently have. If so, then just take it over instead |
| 835 | * of copying it. Note that we are reading am_ref without lock held |
| 836 | * as the value value can only be one if we have the only reference |
| 837 | * to the amap (via our locked map). If the value is greater than |
| 838 | * one, then allocate amap and re-check the value. |
| 839 | */ |
| 840 | |
| 841 | if (srcamap->am_ref == 1) { |
| 842 | entry->etype &= ~UVM_ET_NEEDSCOPY; |
| 843 | UVMHIST_LOG(maphist, "<- done [ref cnt = 1, took it over]" , |
| 844 | 0, 0, 0, 0); |
| 845 | return; |
| 846 | } |
| 847 | |
| 848 | UVMHIST_LOG(maphist," amap=%p, ref=%d, must copy it" , |
| 849 | srcamap, srcamap->am_ref, 0, 0); |
| 850 | |
| 851 | /* |
| 852 | * Allocate a new amap (note: not initialised, no lock set, etc). |
| 853 | */ |
| 854 | |
| 855 | AMAP_B2SLOT(slots, len); |
| 856 | amap = amap_alloc1(slots, 0, waitf); |
| 857 | if (amap == NULL) { |
| 858 | UVMHIST_LOG(maphist, " amap_alloc1 failed" , 0,0,0,0); |
| 859 | return; |
| 860 | } |
| 861 | |
| 862 | amap_lock(srcamap); |
| 863 | |
| 864 | /* |
| 865 | * Re-check the reference count with the lock held. If it has |
| 866 | * dropped to one - we can take over the existing map. |
| 867 | */ |
| 868 | |
| 869 | if (srcamap->am_ref == 1) { |
| 870 | /* Just take over the existing amap. */ |
| 871 | entry->etype &= ~UVM_ET_NEEDSCOPY; |
| 872 | amap_unlock(srcamap); |
| 873 | /* Destroy the new (unused) amap. */ |
| 874 | amap->am_ref--; |
| 875 | amap_free(amap); |
| 876 | return; |
| 877 | } |
| 878 | |
| 879 | /* |
| 880 | * Copy the slots. Zero the padded part. |
| 881 | */ |
| 882 | |
| 883 | UVMHIST_LOG(maphist, " copying amap now" ,0, 0, 0, 0); |
| 884 | for (lcv = 0 ; lcv < slots; lcv++) { |
| 885 | amap->am_anon[lcv] = |
| 886 | srcamap->am_anon[entry->aref.ar_pageoff + lcv]; |
| 887 | if (amap->am_anon[lcv] == NULL) |
| 888 | continue; |
| 889 | KASSERT(amap->am_anon[lcv]->an_lock == srcamap->am_lock); |
| 890 | KASSERT(amap->am_anon[lcv]->an_ref > 0); |
| 891 | KASSERT(amap->am_nused < amap->am_maxslot); |
| 892 | amap->am_anon[lcv]->an_ref++; |
| 893 | amap->am_bckptr[lcv] = amap->am_nused; |
| 894 | amap->am_slots[amap->am_nused] = lcv; |
| 895 | amap->am_nused++; |
| 896 | } |
| 897 | memset(&amap->am_anon[lcv], 0, |
| 898 | (amap->am_maxslot - lcv) * sizeof(struct vm_anon *)); |
| 899 | |
| 900 | /* |
| 901 | * Drop our reference to the old amap (srcamap) and unlock. |
| 902 | * Since the reference count on srcamap is greater than one, |
| 903 | * (we checked above), it cannot drop to zero while it is locked. |
| 904 | */ |
| 905 | |
| 906 | srcamap->am_ref--; |
| 907 | KASSERT(srcamap->am_ref > 0); |
| 908 | |
| 909 | if (srcamap->am_ref == 1 && (srcamap->am_flags & AMAP_SHARED) != 0) { |
| 910 | srcamap->am_flags &= ~AMAP_SHARED; |
| 911 | } |
| 912 | tofree = NULL; |
| 913 | #ifdef UVM_AMAP_PPREF |
| 914 | if (srcamap->am_ppref && srcamap->am_ppref != PPREF_NONE) { |
| 915 | amap_pp_adjref(srcamap, entry->aref.ar_pageoff, |
| 916 | len >> PAGE_SHIFT, -1, &tofree); |
| 917 | } |
| 918 | #endif |
| 919 | |
| 920 | /* |
| 921 | * If we referenced any anons, then share the source amap's lock. |
| 922 | * Otherwise, we have nothing in common, so allocate a new one. |
| 923 | */ |
| 924 | |
| 925 | KASSERT(amap->am_lock == NULL); |
| 926 | if (amap->am_nused != 0) { |
| 927 | amap->am_lock = srcamap->am_lock; |
| 928 | mutex_obj_hold(amap->am_lock); |
| 929 | } |
| 930 | uvm_anon_freelst(srcamap, tofree); |
| 931 | |
| 932 | if (amap->am_lock == NULL) { |
| 933 | amap->am_lock = mutex_obj_alloc(MUTEX_DEFAULT, IPL_NONE); |
| 934 | } |
| 935 | amap_list_insert(amap); |
| 936 | |
| 937 | /* |
| 938 | * Install new amap. |
| 939 | */ |
| 940 | |
| 941 | entry->aref.ar_pageoff = 0; |
| 942 | entry->aref.ar_amap = amap; |
| 943 | entry->etype &= ~UVM_ET_NEEDSCOPY; |
| 944 | UVMHIST_LOG(maphist, "<- done" ,0, 0, 0, 0); |
| 945 | } |
| 946 | |
| 947 | /* |
| 948 | * amap_cow_now: resolve all copy-on-write faults in an amap now for fork(2) |
| 949 | * |
| 950 | * called during fork(2) when the parent process has a wired map |
| 951 | * entry. in that case we want to avoid write-protecting pages |
| 952 | * in the parent's map (e.g. like what you'd do for a COW page) |
| 953 | * so we resolve the COW here. |
| 954 | * |
| 955 | * => assume parent's entry was wired, thus all pages are resident. |
| 956 | * => assume pages that are loaned out (loan_count) are already mapped |
| 957 | * read-only in all maps, and thus no need for us to worry about them |
| 958 | * => assume both parent and child vm_map's are locked |
| 959 | * => caller passes child's map/entry in to us |
| 960 | * => if we run out of memory we will unlock the amap and sleep _with_ the |
| 961 | * parent and child vm_map's locked(!). we have to do this since |
| 962 | * we are in the middle of a fork(2) and we can't let the parent |
| 963 | * map change until we are done copying all the map entrys. |
| 964 | * => XXXCDC: out of memory should cause fork to fail, but there is |
| 965 | * currently no easy way to do this (needs fix) |
| 966 | * => page queues must be unlocked (we may lock them) |
| 967 | */ |
| 968 | |
| 969 | void |
| 970 | amap_cow_now(struct vm_map *map, struct vm_map_entry *entry) |
| 971 | { |
| 972 | struct vm_amap *amap = entry->aref.ar_amap; |
| 973 | struct vm_anon *anon, *nanon; |
| 974 | struct vm_page *pg, *npg; |
| 975 | u_int lcv, slot; |
| 976 | |
| 977 | /* |
| 978 | * note that if we unlock the amap then we must ReStart the "lcv" for |
| 979 | * loop because some other process could reorder the anon's in the |
| 980 | * am_anon[] array on us while the lock is dropped. |
| 981 | */ |
| 982 | |
| 983 | ReStart: |
| 984 | amap_lock(amap); |
| 985 | for (lcv = 0 ; lcv < amap->am_nused ; lcv++) { |
| 986 | slot = amap->am_slots[lcv]; |
| 987 | anon = amap->am_anon[slot]; |
| 988 | KASSERT(anon->an_lock == amap->am_lock); |
| 989 | |
| 990 | /* |
| 991 | * If anon has only one reference - we must have already |
| 992 | * copied it. This can happen if we needed to sleep waiting |
| 993 | * for memory in a previous run through this loop. The new |
| 994 | * page might even have been paged out, since is not wired. |
| 995 | */ |
| 996 | |
| 997 | if (anon->an_ref == 1) { |
| 998 | KASSERT(anon->an_page != NULL || anon->an_swslot != 0); |
| 999 | continue; |
| 1000 | } |
| 1001 | |
| 1002 | /* |
| 1003 | * The old page must be resident since the parent is wired. |
| 1004 | */ |
| 1005 | |
| 1006 | pg = anon->an_page; |
| 1007 | KASSERT(pg != NULL); |
| 1008 | KASSERT(pg->wire_count > 0); |
| 1009 | |
| 1010 | /* |
| 1011 | * If the page is loaned then it must already be mapped |
| 1012 | * read-only and we don't need to copy it. |
| 1013 | */ |
| 1014 | |
| 1015 | if (pg->loan_count != 0) { |
| 1016 | continue; |
| 1017 | } |
| 1018 | KASSERT(pg->uanon == anon && pg->uobject == NULL); |
| 1019 | |
| 1020 | /* |
| 1021 | * If the page is busy, then we have to unlock, wait for |
| 1022 | * it and then restart. |
| 1023 | */ |
| 1024 | |
| 1025 | if (pg->flags & PG_BUSY) { |
| 1026 | pg->flags |= PG_WANTED; |
| 1027 | UVM_UNLOCK_AND_WAIT(pg, amap->am_lock, false, |
| 1028 | "cownow" , 0); |
| 1029 | goto ReStart; |
| 1030 | } |
| 1031 | |
| 1032 | /* |
| 1033 | * Perform a copy-on-write. |
| 1034 | * First - get a new anon and a page. |
| 1035 | */ |
| 1036 | |
| 1037 | nanon = uvm_analloc(); |
| 1038 | if (nanon) { |
| 1039 | nanon->an_lock = amap->am_lock; |
| 1040 | npg = uvm_pagealloc(NULL, 0, nanon, 0); |
| 1041 | } else { |
| 1042 | npg = NULL; |
| 1043 | } |
| 1044 | if (nanon == NULL || npg == NULL) { |
| 1045 | amap_unlock(amap); |
| 1046 | if (nanon) { |
| 1047 | nanon->an_lock = NULL; |
| 1048 | nanon->an_ref--; |
| 1049 | KASSERT(nanon->an_ref == 0); |
| 1050 | uvm_anon_free(nanon); |
| 1051 | } |
| 1052 | uvm_wait("cownowpage" ); |
| 1053 | goto ReStart; |
| 1054 | } |
| 1055 | |
| 1056 | /* |
| 1057 | * Copy the data and replace anon with the new one. |
| 1058 | * Also, setup its lock (share the with amap's lock). |
| 1059 | */ |
| 1060 | |
| 1061 | uvm_pagecopy(pg, npg); |
| 1062 | anon->an_ref--; |
| 1063 | KASSERT(anon->an_ref > 0); |
| 1064 | amap->am_anon[slot] = nanon; |
| 1065 | |
| 1066 | /* |
| 1067 | * Drop PG_BUSY on new page. Since its owner was locked all |
| 1068 | * this time - it cannot be PG_RELEASED or PG_WANTED. |
| 1069 | */ |
| 1070 | |
| 1071 | mutex_enter(&uvm_pageqlock); |
| 1072 | uvm_pageactivate(npg); |
| 1073 | mutex_exit(&uvm_pageqlock); |
| 1074 | npg->flags &= ~(PG_BUSY|PG_FAKE); |
| 1075 | UVM_PAGE_OWN(npg, NULL); |
| 1076 | } |
| 1077 | amap_unlock(amap); |
| 1078 | } |
| 1079 | |
| 1080 | /* |
| 1081 | * amap_splitref: split a single reference into two separate references |
| 1082 | * |
| 1083 | * => called from uvm_map's clip routines |
| 1084 | * => origref's map should be locked |
| 1085 | * => origref->ar_amap should be unlocked (we will lock) |
| 1086 | */ |
| 1087 | void |
| 1088 | amap_splitref(struct vm_aref *origref, struct vm_aref *splitref, vaddr_t offset) |
| 1089 | { |
| 1090 | struct vm_amap *amap = origref->ar_amap; |
| 1091 | u_int leftslots; |
| 1092 | |
| 1093 | KASSERT(splitref->ar_amap == origref->ar_amap); |
| 1094 | AMAP_B2SLOT(leftslots, offset); |
| 1095 | KASSERT(leftslots != 0); |
| 1096 | |
| 1097 | amap_lock(amap); |
| 1098 | KASSERT(amap->am_nslot - origref->ar_pageoff - leftslots > 0); |
| 1099 | |
| 1100 | #ifdef UVM_AMAP_PPREF |
| 1101 | /* Establish ppref before we add a duplicate reference to the amap. */ |
| 1102 | if (amap->am_ppref == NULL) { |
| 1103 | amap_pp_establish(amap, origref->ar_pageoff); |
| 1104 | } |
| 1105 | #endif |
| 1106 | /* Note: not a share reference. */ |
| 1107 | amap->am_ref++; |
| 1108 | splitref->ar_pageoff = origref->ar_pageoff + leftslots; |
| 1109 | amap_unlock(amap); |
| 1110 | } |
| 1111 | |
| 1112 | #ifdef UVM_AMAP_PPREF |
| 1113 | |
| 1114 | /* |
| 1115 | * amap_pp_establish: add a ppref array to an amap, if possible. |
| 1116 | * |
| 1117 | * => amap should be locked by caller. |
| 1118 | */ |
| 1119 | void |
| 1120 | amap_pp_establish(struct vm_amap *amap, vaddr_t offset) |
| 1121 | { |
| 1122 | const size_t sz = amap->am_maxslot * sizeof(*amap->am_ppref); |
| 1123 | |
| 1124 | KASSERT(mutex_owned(amap->am_lock)); |
| 1125 | |
| 1126 | amap->am_ppref = kmem_zalloc(sz, KM_NOSLEEP); |
| 1127 | if (amap->am_ppref == NULL) { |
| 1128 | /* Failure - just do not use ppref. */ |
| 1129 | amap->am_ppref = PPREF_NONE; |
| 1130 | return; |
| 1131 | } |
| 1132 | pp_setreflen(amap->am_ppref, 0, 0, offset); |
| 1133 | pp_setreflen(amap->am_ppref, offset, amap->am_ref, |
| 1134 | amap->am_nslot - offset); |
| 1135 | } |
| 1136 | |
| 1137 | /* |
| 1138 | * amap_pp_adjref: adjust reference count to a part of an amap using the |
| 1139 | * per-page reference count array. |
| 1140 | * |
| 1141 | * => caller must check that ppref != PPREF_NONE before calling. |
| 1142 | * => map and amap must be locked. |
| 1143 | */ |
| 1144 | void |
| 1145 | amap_pp_adjref(struct vm_amap *amap, int curslot, vsize_t slotlen, int adjval, |
| 1146 | struct vm_anon **tofree) |
| 1147 | { |
| 1148 | int stopslot, *ppref, lcv, prevlcv; |
| 1149 | int ref, len, prevref, prevlen; |
| 1150 | |
| 1151 | KASSERT(mutex_owned(amap->am_lock)); |
| 1152 | |
| 1153 | stopslot = curslot + slotlen; |
| 1154 | ppref = amap->am_ppref; |
| 1155 | prevlcv = 0; |
| 1156 | |
| 1157 | /* |
| 1158 | * Advance to the correct place in the array, fragment if needed. |
| 1159 | */ |
| 1160 | |
| 1161 | for (lcv = 0 ; lcv < curslot ; lcv += len) { |
| 1162 | pp_getreflen(ppref, lcv, &ref, &len); |
| 1163 | if (lcv + len > curslot) { /* goes past start? */ |
| 1164 | pp_setreflen(ppref, lcv, ref, curslot - lcv); |
| 1165 | pp_setreflen(ppref, curslot, ref, len - (curslot -lcv)); |
| 1166 | len = curslot - lcv; /* new length of entry @ lcv */ |
| 1167 | } |
| 1168 | prevlcv = lcv; |
| 1169 | } |
| 1170 | if (lcv == 0) { |
| 1171 | /* |
| 1172 | * Ensure that the "prevref == ref" test below always |
| 1173 | * fails, since we are starting from the beginning of |
| 1174 | * the ppref array; that is, there is no previous chunk. |
| 1175 | */ |
| 1176 | prevref = -1; |
| 1177 | prevlen = 0; |
| 1178 | } else { |
| 1179 | pp_getreflen(ppref, prevlcv, &prevref, &prevlen); |
| 1180 | } |
| 1181 | |
| 1182 | /* |
| 1183 | * Now adjust reference counts in range. Merge the first |
| 1184 | * changed entry with the last unchanged entry if possible. |
| 1185 | */ |
| 1186 | KASSERT(lcv == curslot); |
| 1187 | for (/* lcv already set */; lcv < stopslot ; lcv += len) { |
| 1188 | pp_getreflen(ppref, lcv, &ref, &len); |
| 1189 | if (lcv + len > stopslot) { /* goes past end? */ |
| 1190 | pp_setreflen(ppref, lcv, ref, stopslot - lcv); |
| 1191 | pp_setreflen(ppref, stopslot, ref, |
| 1192 | len - (stopslot - lcv)); |
| 1193 | len = stopslot - lcv; |
| 1194 | } |
| 1195 | ref += adjval; |
| 1196 | KASSERT(ref >= 0); |
| 1197 | KASSERT(ref <= amap->am_ref); |
| 1198 | if (lcv == prevlcv + prevlen && ref == prevref) { |
| 1199 | pp_setreflen(ppref, prevlcv, ref, prevlen + len); |
| 1200 | } else { |
| 1201 | pp_setreflen(ppref, lcv, ref, len); |
| 1202 | } |
| 1203 | if (ref == 0) { |
| 1204 | amap_wiperange(amap, lcv, len, tofree); |
| 1205 | } |
| 1206 | } |
| 1207 | } |
| 1208 | |
| 1209 | /* |
| 1210 | * amap_wiperange: wipe out a range of an amap. |
| 1211 | * Note: different from amap_wipeout because the amap is kept intact. |
| 1212 | * |
| 1213 | * => Both map and amap must be locked by caller. |
| 1214 | */ |
| 1215 | void |
| 1216 | amap_wiperange(struct vm_amap *amap, int slotoff, int slots, |
| 1217 | struct vm_anon **tofree) |
| 1218 | { |
| 1219 | u_int lcv, stop, slotend; |
| 1220 | bool byanon; |
| 1221 | |
| 1222 | KASSERT(mutex_owned(amap->am_lock)); |
| 1223 | |
| 1224 | /* |
| 1225 | * We can either traverse the amap by am_anon or by am_slots. |
| 1226 | * Determine which way is less expensive. |
| 1227 | */ |
| 1228 | |
| 1229 | if (slots < amap->am_nused) { |
| 1230 | byanon = true; |
| 1231 | lcv = slotoff; |
| 1232 | stop = slotoff + slots; |
| 1233 | slotend = 0; |
| 1234 | } else { |
| 1235 | byanon = false; |
| 1236 | lcv = 0; |
| 1237 | stop = amap->am_nused; |
| 1238 | slotend = slotoff + slots; |
| 1239 | } |
| 1240 | |
| 1241 | while (lcv < stop) { |
| 1242 | struct vm_anon *anon; |
| 1243 | u_int curslot, ptr, last; |
| 1244 | |
| 1245 | if (byanon) { |
| 1246 | curslot = lcv++; /* lcv advances here */ |
| 1247 | if (amap->am_anon[curslot] == NULL) |
| 1248 | continue; |
| 1249 | } else { |
| 1250 | curslot = amap->am_slots[lcv]; |
| 1251 | if (curslot < slotoff || curslot >= slotend) { |
| 1252 | lcv++; /* lcv advances here */ |
| 1253 | continue; |
| 1254 | } |
| 1255 | stop--; /* drop stop, since anon will be removed */ |
| 1256 | } |
| 1257 | anon = amap->am_anon[curslot]; |
| 1258 | KASSERT(anon->an_lock == amap->am_lock); |
| 1259 | |
| 1260 | /* |
| 1261 | * Remove anon from the amap. |
| 1262 | */ |
| 1263 | |
| 1264 | amap->am_anon[curslot] = NULL; |
| 1265 | ptr = amap->am_bckptr[curslot]; |
| 1266 | last = amap->am_nused - 1; |
| 1267 | if (ptr != last) { |
| 1268 | amap->am_slots[ptr] = amap->am_slots[last]; |
| 1269 | amap->am_bckptr[amap->am_slots[ptr]] = ptr; |
| 1270 | } |
| 1271 | amap->am_nused--; |
| 1272 | |
| 1273 | /* |
| 1274 | * Drop its reference count. |
| 1275 | */ |
| 1276 | |
| 1277 | KASSERT(anon->an_lock == amap->am_lock); |
| 1278 | if (--anon->an_ref == 0) { |
| 1279 | /* |
| 1280 | * Eliminated the last reference to an anon - defer |
| 1281 | * freeing as uvm_anon_freelst() will unlock the amap. |
| 1282 | */ |
| 1283 | anon->an_link = *tofree; |
| 1284 | *tofree = anon; |
| 1285 | } |
| 1286 | } |
| 1287 | } |
| 1288 | |
| 1289 | #endif |
| 1290 | |
| 1291 | #if defined(VMSWAP) |
| 1292 | |
| 1293 | /* |
| 1294 | * amap_swap_off: pagein anonymous pages in amaps and drop swap slots. |
| 1295 | * |
| 1296 | * => called with swap_syscall_lock held. |
| 1297 | * => note that we don't always traverse all anons. |
| 1298 | * eg. amaps being wiped out, released anons. |
| 1299 | * => return true if failed. |
| 1300 | */ |
| 1301 | |
| 1302 | bool |
| 1303 | amap_swap_off(int startslot, int endslot) |
| 1304 | { |
| 1305 | struct vm_amap *am; |
| 1306 | struct vm_amap *am_next; |
| 1307 | struct vm_amap marker_prev; |
| 1308 | struct vm_amap marker_next; |
| 1309 | bool rv = false; |
| 1310 | |
| 1311 | #if defined(DIAGNOSTIC) |
| 1312 | memset(&marker_prev, 0, sizeof(marker_prev)); |
| 1313 | memset(&marker_next, 0, sizeof(marker_next)); |
| 1314 | #endif /* defined(DIAGNOSTIC) */ |
| 1315 | |
| 1316 | mutex_enter(&amap_list_lock); |
| 1317 | for (am = LIST_FIRST(&amap_list); am != NULL && !rv; am = am_next) { |
| 1318 | int i; |
| 1319 | |
| 1320 | LIST_INSERT_BEFORE(am, &marker_prev, am_list); |
| 1321 | LIST_INSERT_AFTER(am, &marker_next, am_list); |
| 1322 | |
| 1323 | if (!amap_lock_try(am)) { |
| 1324 | mutex_exit(&amap_list_lock); |
| 1325 | preempt(); |
| 1326 | mutex_enter(&amap_list_lock); |
| 1327 | am_next = LIST_NEXT(&marker_prev, am_list); |
| 1328 | if (am_next == &marker_next) { |
| 1329 | am_next = LIST_NEXT(am_next, am_list); |
| 1330 | } else { |
| 1331 | KASSERT(LIST_NEXT(am_next, am_list) == |
| 1332 | &marker_next); |
| 1333 | } |
| 1334 | LIST_REMOVE(&marker_prev, am_list); |
| 1335 | LIST_REMOVE(&marker_next, am_list); |
| 1336 | continue; |
| 1337 | } |
| 1338 | |
| 1339 | mutex_exit(&amap_list_lock); |
| 1340 | |
| 1341 | if (am->am_nused <= 0) { |
| 1342 | amap_unlock(am); |
| 1343 | goto next; |
| 1344 | } |
| 1345 | |
| 1346 | for (i = 0; i < am->am_nused; i++) { |
| 1347 | int slot; |
| 1348 | int swslot; |
| 1349 | struct vm_anon *anon; |
| 1350 | |
| 1351 | slot = am->am_slots[i]; |
| 1352 | anon = am->am_anon[slot]; |
| 1353 | KASSERT(anon->an_lock == am->am_lock); |
| 1354 | |
| 1355 | swslot = anon->an_swslot; |
| 1356 | if (swslot < startslot || endslot <= swslot) { |
| 1357 | continue; |
| 1358 | } |
| 1359 | |
| 1360 | am->am_flags |= AMAP_SWAPOFF; |
| 1361 | |
| 1362 | rv = uvm_anon_pagein(am, anon); |
| 1363 | amap_lock(am); |
| 1364 | |
| 1365 | am->am_flags &= ~AMAP_SWAPOFF; |
| 1366 | if (amap_refs(am) == 0) { |
| 1367 | amap_wipeout(am); |
| 1368 | am = NULL; |
| 1369 | break; |
| 1370 | } |
| 1371 | if (rv) { |
| 1372 | break; |
| 1373 | } |
| 1374 | i = 0; |
| 1375 | } |
| 1376 | |
| 1377 | if (am) { |
| 1378 | amap_unlock(am); |
| 1379 | } |
| 1380 | |
| 1381 | next: |
| 1382 | mutex_enter(&amap_list_lock); |
| 1383 | KASSERT(LIST_NEXT(&marker_prev, am_list) == &marker_next || |
| 1384 | LIST_NEXT(LIST_NEXT(&marker_prev, am_list), am_list) == |
| 1385 | &marker_next); |
| 1386 | am_next = LIST_NEXT(&marker_next, am_list); |
| 1387 | LIST_REMOVE(&marker_prev, am_list); |
| 1388 | LIST_REMOVE(&marker_next, am_list); |
| 1389 | } |
| 1390 | mutex_exit(&amap_list_lock); |
| 1391 | |
| 1392 | return rv; |
| 1393 | } |
| 1394 | |
| 1395 | #endif /* defined(VMSWAP) */ |
| 1396 | |
| 1397 | /* |
| 1398 | * amap_lookup: look up a page in an amap. |
| 1399 | * |
| 1400 | * => amap should be locked by caller. |
| 1401 | */ |
| 1402 | struct vm_anon * |
| 1403 | amap_lookup(struct vm_aref *aref, vaddr_t offset) |
| 1404 | { |
| 1405 | struct vm_amap *amap = aref->ar_amap; |
| 1406 | struct vm_anon *an; |
| 1407 | u_int slot; |
| 1408 | |
| 1409 | UVMHIST_FUNC("amap_lookup" ); UVMHIST_CALLED(maphist); |
| 1410 | KASSERT(mutex_owned(amap->am_lock)); |
| 1411 | |
| 1412 | AMAP_B2SLOT(slot, offset); |
| 1413 | slot += aref->ar_pageoff; |
| 1414 | an = amap->am_anon[slot]; |
| 1415 | |
| 1416 | UVMHIST_LOG(maphist, "<- done (amap=0x%x, offset=0x%x, result=0x%x)" , |
| 1417 | amap, offset, an, 0); |
| 1418 | |
| 1419 | KASSERT(slot < amap->am_nslot); |
| 1420 | KASSERT(an == NULL || an->an_ref != 0); |
| 1421 | KASSERT(an == NULL || an->an_lock == amap->am_lock); |
| 1422 | return an; |
| 1423 | } |
| 1424 | |
| 1425 | /* |
| 1426 | * amap_lookups: look up a range of pages in an amap. |
| 1427 | * |
| 1428 | * => amap should be locked by caller. |
| 1429 | */ |
| 1430 | void |
| 1431 | amap_lookups(struct vm_aref *aref, vaddr_t offset, struct vm_anon **anons, |
| 1432 | int npages) |
| 1433 | { |
| 1434 | struct vm_amap *amap = aref->ar_amap; |
| 1435 | u_int slot; |
| 1436 | |
| 1437 | UVMHIST_FUNC("amap_lookups" ); UVMHIST_CALLED(maphist); |
| 1438 | KASSERT(mutex_owned(amap->am_lock)); |
| 1439 | |
| 1440 | AMAP_B2SLOT(slot, offset); |
| 1441 | slot += aref->ar_pageoff; |
| 1442 | |
| 1443 | UVMHIST_LOG(maphist, " slot=%u, npages=%d, nslot=%d" , |
| 1444 | slot, npages, amap->am_nslot, 0); |
| 1445 | |
| 1446 | KASSERT((slot + (npages - 1)) < amap->am_nslot); |
| 1447 | memcpy(anons, &amap->am_anon[slot], npages * sizeof(struct vm_anon *)); |
| 1448 | |
| 1449 | #if defined(DIAGNOSTIC) |
| 1450 | for (int i = 0; i < npages; i++) { |
| 1451 | struct vm_anon * const an = anons[i]; |
| 1452 | if (an == NULL) { |
| 1453 | continue; |
| 1454 | } |
| 1455 | KASSERT(an->an_ref != 0); |
| 1456 | KASSERT(an->an_lock == amap->am_lock); |
| 1457 | } |
| 1458 | #endif |
| 1459 | UVMHIST_LOG(maphist, "<- done" , 0, 0, 0, 0); |
| 1460 | } |
| 1461 | |
| 1462 | /* |
| 1463 | * amap_add: add (or replace) a page to an amap. |
| 1464 | * |
| 1465 | * => amap should be locked by caller. |
| 1466 | * => anon must have the lock associated with this amap. |
| 1467 | */ |
| 1468 | void |
| 1469 | amap_add(struct vm_aref *aref, vaddr_t offset, struct vm_anon *anon, |
| 1470 | bool replace) |
| 1471 | { |
| 1472 | struct vm_amap *amap = aref->ar_amap; |
| 1473 | u_int slot; |
| 1474 | |
| 1475 | UVMHIST_FUNC("amap_add" ); UVMHIST_CALLED(maphist); |
| 1476 | KASSERT(mutex_owned(amap->am_lock)); |
| 1477 | KASSERT(anon->an_lock == amap->am_lock); |
| 1478 | |
| 1479 | AMAP_B2SLOT(slot, offset); |
| 1480 | slot += aref->ar_pageoff; |
| 1481 | KASSERT(slot < amap->am_nslot); |
| 1482 | |
| 1483 | if (replace) { |
| 1484 | struct vm_anon *oanon = amap->am_anon[slot]; |
| 1485 | |
| 1486 | KASSERT(oanon != NULL); |
| 1487 | if (oanon->an_page && (amap->am_flags & AMAP_SHARED) != 0) { |
| 1488 | pmap_page_protect(oanon->an_page, VM_PROT_NONE); |
| 1489 | /* |
| 1490 | * XXX: suppose page is supposed to be wired somewhere? |
| 1491 | */ |
| 1492 | } |
| 1493 | } else { |
| 1494 | KASSERT(amap->am_anon[slot] == NULL); |
| 1495 | KASSERT(amap->am_nused < amap->am_maxslot); |
| 1496 | amap->am_bckptr[slot] = amap->am_nused; |
| 1497 | amap->am_slots[amap->am_nused] = slot; |
| 1498 | amap->am_nused++; |
| 1499 | } |
| 1500 | amap->am_anon[slot] = anon; |
| 1501 | UVMHIST_LOG(maphist, |
| 1502 | "<- done (amap=0x%x, offset=0x%x, anon=0x%x, rep=%d)" , |
| 1503 | amap, offset, anon, replace); |
| 1504 | } |
| 1505 | |
| 1506 | /* |
| 1507 | * amap_unadd: remove a page from an amap. |
| 1508 | * |
| 1509 | * => amap should be locked by caller. |
| 1510 | */ |
| 1511 | void |
| 1512 | amap_unadd(struct vm_aref *aref, vaddr_t offset) |
| 1513 | { |
| 1514 | struct vm_amap *amap = aref->ar_amap; |
| 1515 | u_int slot, ptr, last; |
| 1516 | |
| 1517 | UVMHIST_FUNC("amap_unadd" ); UVMHIST_CALLED(maphist); |
| 1518 | KASSERT(mutex_owned(amap->am_lock)); |
| 1519 | |
| 1520 | AMAP_B2SLOT(slot, offset); |
| 1521 | slot += aref->ar_pageoff; |
| 1522 | KASSERT(slot < amap->am_nslot); |
| 1523 | KASSERT(amap->am_anon[slot] != NULL); |
| 1524 | KASSERT(amap->am_anon[slot]->an_lock == amap->am_lock); |
| 1525 | |
| 1526 | amap->am_anon[slot] = NULL; |
| 1527 | ptr = amap->am_bckptr[slot]; |
| 1528 | |
| 1529 | last = amap->am_nused - 1; |
| 1530 | if (ptr != last) { |
| 1531 | /* Move the last entry to keep the slots contiguous. */ |
| 1532 | amap->am_slots[ptr] = amap->am_slots[last]; |
| 1533 | amap->am_bckptr[amap->am_slots[ptr]] = ptr; |
| 1534 | } |
| 1535 | amap->am_nused--; |
| 1536 | UVMHIST_LOG(maphist, "<- done (amap=0x%x, slot=0x%x)" , amap, slot,0, 0); |
| 1537 | } |
| 1538 | |
| 1539 | /* |
| 1540 | * amap_adjref_anons: adjust the reference count(s) on amap and its anons. |
| 1541 | */ |
| 1542 | static void |
| 1543 | amap_adjref_anons(struct vm_amap *amap, vaddr_t offset, vsize_t len, |
| 1544 | int refv, bool all) |
| 1545 | { |
| 1546 | struct vm_anon *tofree = NULL; |
| 1547 | |
| 1548 | #ifdef UVM_AMAP_PPREF |
| 1549 | KASSERT(mutex_owned(amap->am_lock)); |
| 1550 | |
| 1551 | /* |
| 1552 | * We must establish the ppref array before changing am_ref |
| 1553 | * so that the ppref values match the current amap refcount. |
| 1554 | */ |
| 1555 | |
| 1556 | if (amap->am_ppref == NULL && !all && len != amap->am_nslot) { |
| 1557 | amap_pp_establish(amap, offset); |
| 1558 | } |
| 1559 | #endif |
| 1560 | |
| 1561 | amap->am_ref += refv; |
| 1562 | |
| 1563 | #ifdef UVM_AMAP_PPREF |
| 1564 | if (amap->am_ppref && amap->am_ppref != PPREF_NONE) { |
| 1565 | if (all) { |
| 1566 | amap_pp_adjref(amap, 0, amap->am_nslot, refv, &tofree); |
| 1567 | } else { |
| 1568 | amap_pp_adjref(amap, offset, len, refv, &tofree); |
| 1569 | } |
| 1570 | } |
| 1571 | #endif |
| 1572 | uvm_anon_freelst(amap, tofree); |
| 1573 | } |
| 1574 | |
| 1575 | /* |
| 1576 | * amap_ref: gain a reference to an amap. |
| 1577 | * |
| 1578 | * => amap must not be locked (we will lock). |
| 1579 | * => "offset" and "len" are in units of pages. |
| 1580 | * => Called at fork time to gain the child's reference. |
| 1581 | */ |
| 1582 | void |
| 1583 | amap_ref(struct vm_amap *amap, vaddr_t offset, vsize_t len, int flags) |
| 1584 | { |
| 1585 | UVMHIST_FUNC("amap_ref" ); UVMHIST_CALLED(maphist); |
| 1586 | |
| 1587 | amap_lock(amap); |
| 1588 | if (flags & AMAP_SHARED) { |
| 1589 | amap->am_flags |= AMAP_SHARED; |
| 1590 | } |
| 1591 | amap_adjref_anons(amap, offset, len, 1, (flags & AMAP_REFALL) != 0); |
| 1592 | |
| 1593 | UVMHIST_LOG(maphist,"<- done! amap=0x%x" , amap, 0, 0, 0); |
| 1594 | } |
| 1595 | |
| 1596 | /* |
| 1597 | * amap_unref: remove a reference to an amap. |
| 1598 | * |
| 1599 | * => All pmap-level references to this amap must be already removed. |
| 1600 | * => Called from uvm_unmap_detach(); entry is already removed from the map. |
| 1601 | * => We will lock amap, so it must be unlocked. |
| 1602 | */ |
| 1603 | void |
| 1604 | amap_unref(struct vm_amap *amap, vaddr_t offset, vsize_t len, bool all) |
| 1605 | { |
| 1606 | UVMHIST_FUNC("amap_unref" ); UVMHIST_CALLED(maphist); |
| 1607 | |
| 1608 | amap_lock(amap); |
| 1609 | |
| 1610 | UVMHIST_LOG(maphist," amap=0x%x refs=%d, nused=%d" , |
| 1611 | amap, amap->am_ref, amap->am_nused, 0); |
| 1612 | KASSERT(amap->am_ref > 0); |
| 1613 | |
| 1614 | if (amap->am_ref == 1) { |
| 1615 | |
| 1616 | /* |
| 1617 | * If the last reference - wipeout and destroy the amap. |
| 1618 | */ |
| 1619 | amap->am_ref--; |
| 1620 | amap_wipeout(amap); |
| 1621 | UVMHIST_LOG(maphist,"<- done (was last ref)!" , 0, 0, 0, 0); |
| 1622 | return; |
| 1623 | } |
| 1624 | |
| 1625 | /* |
| 1626 | * Otherwise, drop the reference count(s) on anons. |
| 1627 | */ |
| 1628 | |
| 1629 | if (amap->am_ref == 2 && (amap->am_flags & AMAP_SHARED) != 0) { |
| 1630 | amap->am_flags &= ~AMAP_SHARED; |
| 1631 | } |
| 1632 | amap_adjref_anons(amap, offset, len, -1, all); |
| 1633 | |
| 1634 | UVMHIST_LOG(maphist,"<- done!" , 0, 0, 0, 0); |
| 1635 | } |
| 1636 | |