1 /* $OpenBSD: uvm_device.c,v 1.37 2009/08/14 16:27:34 oga Exp $ */ 2 /* $NetBSD: uvm_device.c,v 1.30 2000/11/25 06:27:59 chs Exp $ */ 3 4 /* 5 * 6 * Copyright (c) 1997 Charles D. Cranor and Washington University. 7 * All rights reserved. 8 * 9 * Redistribution and use in source and binary forms, with or without 10 * modification, are permitted provided that the following conditions 11 * are met: 12 * 1. Redistributions of source code must retain the above copyright 13 * notice, this list of conditions and the following disclaimer. 14 * 2. Redistributions in binary form must reproduce the above copyright 15 * notice, this list of conditions and the following disclaimer in the 16 * documentation and/or other materials provided with the distribution. 17 * 3. All advertising materials mentioning features or use of this software 18 * must display the following acknowledgement: 19 * This product includes software developed by Charles D. Cranor and 20 * Washington University. 21 * 4. The name of the author may not be used to endorse or promote products 22 * derived from this software without specific prior written permission. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 25 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 26 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 27 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 28 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 29 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 30 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 31 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 32 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 33 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 34 * 35 * from: Id: uvm_device.c,v 1.1.2.9 1998/02/06 05:11:47 chs Exp 36 */ 37 38 /* 39 * uvm_device.c: the device pager. 40 */ 41 42 #include <sys/param.h> 43 #include <sys/systm.h> 44 #include <sys/conf.h> 45 #include <sys/proc.h> 46 #include <sys/malloc.h> 47 #include <sys/mutex.h> 48 #include <sys/vnode.h> 49 50 #include <uvm/uvm.h> 51 #include <uvm/uvm_device.h> 52 53 /* 54 * private global data structure 55 * 56 * we keep a list of active device objects in the system. 57 */ 58 59 LIST_HEAD(, uvm_device) udv_list = LIST_HEAD_INITIALIZER(udv_list); 60 struct mutex udv_lock = MUTEX_INITIALIZER(IPL_NONE); 61 62 /* 63 * functions 64 */ 65 66 static void udv_reference(struct uvm_object *); 67 static void udv_detach(struct uvm_object *); 68 static int udv_fault(struct uvm_faultinfo *, vaddr_t, 69 vm_page_t *, int, int, vm_fault_t, 70 vm_prot_t, int); 71 static boolean_t udv_flush(struct uvm_object *, voff_t, voff_t, 72 int); 73 74 /* 75 * master pager structure 76 */ 77 78 struct uvm_pagerops uvm_deviceops = { 79 NULL, /* inited statically */ 80 udv_reference, 81 udv_detach, 82 udv_fault, 83 udv_flush, 84 }; 85 86 /* 87 * the ops. 88 */ 89 90 91 /* 92 * udv_attach 93 * 94 * get a VM object that is associated with a device. allocate a new 95 * one if needed. 96 * 97 * => caller must _not_ already be holding the lock on the uvm_object. 98 * => in fact, nothing should be locked so that we can sleep here. 99 * 100 * The last two arguments (off and size) are only used for access checking. 101 */ 102 struct uvm_object * 103 udv_attach(void *arg, vm_prot_t accessprot, voff_t off, vsize_t size) 104 { 105 dev_t device = *((dev_t *)arg); 106 struct uvm_device *udv, *lcv; 107 paddr_t (*mapfn)(dev_t, off_t, int); 108 UVMHIST_FUNC("udv_attach"); UVMHIST_CALLED(maphist); 109 110 UVMHIST_LOG(maphist, "(device=0x%lx)", device,0,0,0); 111 112 /* 113 * before we do anything, ensure this device supports mmap 114 */ 115 116 mapfn = cdevsw[major(device)].d_mmap; 117 if (mapfn == NULL || 118 mapfn == (paddr_t (*)(dev_t, off_t, int)) enodev || 119 mapfn == (paddr_t (*)(dev_t, off_t, int)) nullop) 120 return(NULL); 121 122 /* 123 * Negative offsets on the object are not allowed. 124 */ 125 126 if (off < 0) 127 return(NULL); 128 129 /* 130 * Check that the specified range of the device allows the 131 * desired protection. 132 * 133 * XXX assumes VM_PROT_* == PROT_* 134 * XXX clobbers off and size, but nothing else here needs them. 135 */ 136 137 while (size != 0) { 138 if ((*mapfn)(device, off, accessprot) == -1) 139 return (NULL); 140 off += PAGE_SIZE; size -= PAGE_SIZE; 141 } 142 143 /* 144 * keep looping until we get it 145 */ 146 147 for (;;) { 148 149 /* 150 * first, attempt to find it on the main list 151 */ 152 153 mtx_enter(&udv_lock); 154 LIST_FOREACH(lcv, &udv_list, u_list) { 155 if (device == lcv->u_device) 156 break; 157 } 158 159 /* 160 * got it on main list. put a hold on it and unlock udv_lock. 161 */ 162 163 if (lcv) { 164 165 /* 166 * if someone else has a hold on it, sleep and start 167 * over again. Else, we need take HOLD flag so we 168 * don't have to re-order locking here. 169 */ 170 171 if (lcv->u_flags & UVM_DEVICE_HOLD) { 172 lcv->u_flags |= UVM_DEVICE_WANTED; 173 msleep(lcv, &udv_lock, PVM | PNORELOCK, 174 "udv_attach", 0); 175 continue; 176 } 177 178 /* we are now holding it */ 179 lcv->u_flags |= UVM_DEVICE_HOLD; 180 mtx_leave(&udv_lock); 181 182 /* 183 * bump reference count, unhold, return. 184 */ 185 186 simple_lock(&lcv->u_obj.vmobjlock); 187 lcv->u_obj.uo_refs++; 188 simple_unlock(&lcv->u_obj.vmobjlock); 189 190 mtx_enter(&udv_lock); 191 if (lcv->u_flags & UVM_DEVICE_WANTED) 192 wakeup(lcv); 193 lcv->u_flags &= ~(UVM_DEVICE_WANTED|UVM_DEVICE_HOLD); 194 mtx_leave(&udv_lock); 195 return(&lcv->u_obj); 196 } 197 198 /* 199 * did not find it on main list. need to malloc a new one. 200 */ 201 202 mtx_leave(&udv_lock); 203 /* NOTE: we could sleep in the following malloc() */ 204 udv = malloc(sizeof(*udv), M_TEMP, M_WAITOK); 205 mtx_enter(&udv_lock); 206 207 /* 208 * now we have to double check to make sure no one added it 209 * to the list while we were sleeping... 210 */ 211 212 LIST_FOREACH(lcv, &udv_list, u_list) { 213 if (device == lcv->u_device) 214 break; 215 } 216 217 /* 218 * did we lose a race to someone else? 219 * free our memory and retry. 220 */ 221 222 if (lcv) { 223 mtx_leave(&udv_lock); 224 free(udv, M_TEMP); 225 continue; 226 } 227 228 /* 229 * we have it! init the data structures, add to list 230 * and return. 231 */ 232 233 simple_lock_init(&udv->u_obj.vmobjlock); 234 udv->u_obj.pgops = &uvm_deviceops; 235 RB_INIT(&udv->u_obj.memt); 236 udv->u_obj.uo_npages = 0; 237 udv->u_obj.uo_refs = 1; 238 udv->u_flags = 0; 239 udv->u_device = device; 240 LIST_INSERT_HEAD(&udv_list, udv, u_list); 241 mtx_leave(&udv_lock); 242 return(&udv->u_obj); 243 } 244 /*NOTREACHED*/ 245 } 246 247 /* 248 * udv_reference 249 * 250 * add a reference to a VM object. Note that the reference count must 251 * already be one (the passed in reference) so there is no chance of the 252 * udv being released or locked out here. 253 * 254 * => caller must call with object unlocked. 255 */ 256 257 static void 258 udv_reference(struct uvm_object *uobj) 259 { 260 UVMHIST_FUNC("udv_reference"); UVMHIST_CALLED(maphist); 261 262 simple_lock(&uobj->vmobjlock); 263 uobj->uo_refs++; 264 UVMHIST_LOG(maphist, "<- done (uobj=%p, ref = %ld)", 265 uobj, uobj->uo_refs,0,0); 266 simple_unlock(&uobj->vmobjlock); 267 } 268 269 /* 270 * udv_detach 271 * 272 * remove a reference to a VM object. 273 * 274 * => caller must call with object unlocked and map locked. 275 */ 276 277 static void 278 udv_detach(struct uvm_object *uobj) 279 { 280 struct uvm_device *udv = (struct uvm_device *)uobj; 281 UVMHIST_FUNC("udv_detach"); UVMHIST_CALLED(maphist); 282 283 /* 284 * loop until done 285 */ 286 again: 287 simple_lock(&uobj->vmobjlock); 288 if (uobj->uo_refs > 1) { 289 uobj->uo_refs--; 290 simple_unlock(&uobj->vmobjlock); 291 UVMHIST_LOG(maphist," <- done, uobj=%p, ref=%ld", 292 uobj,uobj->uo_refs,0,0); 293 return; 294 } 295 KASSERT(uobj->uo_npages == 0 && RB_EMPTY(&uobj->memt)); 296 297 /* 298 * is it being held? if so, wait until others are done. 299 */ 300 301 mtx_enter(&udv_lock); 302 if (udv->u_flags & UVM_DEVICE_HOLD) { 303 udv->u_flags |= UVM_DEVICE_WANTED; 304 /* 305 * lock interleaving. -- this is ok in this case since the 306 * locks are both IPL_NONE 307 */ 308 simple_unlock(&uobj->vmobjlock); 309 msleep(udv, &udv_lock, PVM | PNORELOCK, "udv_detach", 0); 310 goto again; 311 } 312 313 /* 314 * got it! nuke it now. 315 */ 316 317 LIST_REMOVE(udv, u_list); 318 if (udv->u_flags & UVM_DEVICE_WANTED) 319 wakeup(udv); 320 mtx_leave(&udv_lock); 321 simple_unlock(&uobj->vmobjlock); 322 free(udv, M_TEMP); 323 UVMHIST_LOG(maphist," <- done, freed uobj=%p", uobj,0,0,0); 324 } 325 326 327 /* 328 * udv_flush 329 * 330 * flush pages out of a uvm object. a no-op for devices. 331 */ 332 333 static boolean_t 334 udv_flush(struct uvm_object *uobj, voff_t start, voff_t stop, int flags) 335 { 336 337 return(TRUE); 338 } 339 340 /* 341 * udv_fault: non-standard fault routine for device "pages" 342 * 343 * => rather than having a "get" function, we have a fault routine 344 * since we don't return vm_pages we need full control over the 345 * pmap_enter map in 346 * => all the usual fault data structured are locked by the caller 347 * (i.e. maps(read), amap (if any), uobj) 348 * => on return, we unlock all fault data structures 349 * => flags: PGO_ALLPAGES: get all of the pages 350 * PGO_LOCKED: fault data structures are locked 351 * XXX: currently PGO_LOCKED is always required ... consider removing 352 * it as a flag 353 * => NOTE: vaddr is the VA of pps[0] in ufi->entry, _NOT_ pps[centeridx] 354 */ 355 356 static int 357 udv_fault(struct uvm_faultinfo *ufi, vaddr_t vaddr, vm_page_t *pps, int npages, 358 int centeridx, vm_fault_t fault_type, vm_prot_t access_type, int flags) 359 { 360 struct vm_map_entry *entry = ufi->entry; 361 struct uvm_object *uobj = entry->object.uvm_obj; 362 struct uvm_device *udv = (struct uvm_device *)uobj; 363 vaddr_t curr_va; 364 off_t curr_offset; 365 paddr_t paddr, mdpgno; 366 int lcv, retval; 367 dev_t device; 368 paddr_t (*mapfn)(dev_t, off_t, int); 369 vm_prot_t mapprot; 370 UVMHIST_FUNC("udv_fault"); UVMHIST_CALLED(maphist); 371 UVMHIST_LOG(maphist," flags=%ld", flags,0,0,0); 372 373 /* 374 * we do not allow device mappings to be mapped copy-on-write 375 * so we kill any attempt to do so here. 376 */ 377 378 if (UVM_ET_ISCOPYONWRITE(entry)) { 379 UVMHIST_LOG(maphist, "<- failed -- COW entry (etype=0x%lx)", 380 entry->etype, 0,0,0); 381 uvmfault_unlockall(ufi, ufi->entry->aref.ar_amap, uobj, NULL); 382 return(VM_PAGER_ERROR); 383 } 384 385 /* 386 * get device map function. 387 */ 388 389 device = udv->u_device; 390 mapfn = cdevsw[major(device)].d_mmap; 391 392 /* 393 * now we must determine the offset in udv to use and the VA to 394 * use for pmap_enter. note that we always use orig_map's pmap 395 * for pmap_enter (even if we have a submap). since virtual 396 * addresses in a submap must match the main map, this is ok. 397 */ 398 399 /* udv offset = (offset from start of entry) + entry's offset */ 400 curr_offset = entry->offset + (vaddr - entry->start); 401 /* pmap va = vaddr (virtual address of pps[0]) */ 402 curr_va = vaddr; 403 404 /* 405 * loop over the page range entering in as needed 406 */ 407 408 retval = VM_PAGER_OK; 409 for (lcv = 0 ; lcv < npages ; lcv++, curr_offset += PAGE_SIZE, 410 curr_va += PAGE_SIZE) { 411 if ((flags & PGO_ALLPAGES) == 0 && lcv != centeridx) 412 continue; 413 414 if (pps[lcv] == PGO_DONTCARE) 415 continue; 416 417 mdpgno = (*mapfn)(device, curr_offset, access_type); 418 if (mdpgno == -1) { 419 retval = VM_PAGER_ERROR; 420 break; 421 } 422 paddr = pmap_phys_address(mdpgno); 423 mapprot = ufi->entry->protection; 424 UVMHIST_LOG(maphist, 425 " MAPPING: device: pm=%p, va=0x%lx, pa=0x%lx, at=%ld", 426 ufi->orig_map->pmap, curr_va, (u_long)paddr, mapprot); 427 if (pmap_enter(ufi->orig_map->pmap, curr_va, paddr, 428 mapprot, PMAP_CANFAIL | mapprot) != 0) { 429 /* 430 * pmap_enter() didn't have the resource to 431 * enter this mapping. Unlock everything, 432 * wait for the pagedaemon to free up some 433 * pages, and then tell uvm_fault() to start 434 * the fault again. 435 * 436 * XXX Needs some rethinking for the PGO_ALLPAGES 437 * XXX case. 438 */ 439 uvmfault_unlockall(ufi, ufi->entry->aref.ar_amap, 440 uobj, NULL); 441 442 /* sync what we have so far */ 443 pmap_update(ufi->orig_map->pmap); 444 uvm_wait("udv_fault"); 445 return (VM_PAGER_REFAULT); 446 } 447 } 448 449 uvmfault_unlockall(ufi, ufi->entry->aref.ar_amap, uobj, NULL); 450 pmap_update(ufi->orig_map->pmap); 451 return (retval); 452 } 453