1 /* $NetBSD: uvm_device.c,v 1.60 2011/02/12 14:45:31 jmcneill 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 * from: Id: uvm_device.c,v 1.1.2.9 1998/02/06 05:11:47 chs Exp 28 */ 29 30 /* 31 * uvm_device.c: the device pager. 32 */ 33 34 #include <sys/cdefs.h> 35 __KERNEL_RCSID(0, "$NetBSD: uvm_device.c,v 1.60 2011/02/12 14:45:31 jmcneill Exp $"); 36 37 #include "opt_uvmhist.h" 38 39 #include <sys/param.h> 40 #include <sys/systm.h> 41 #include <sys/conf.h> 42 #include <sys/proc.h> 43 #include <sys/malloc.h> 44 45 #include <uvm/uvm.h> 46 #include <uvm/uvm_device.h> 47 #include <uvm/uvm_pmap.h> 48 49 /* 50 * private global data structure 51 * 52 * we keep a list of active device objects in the system. 53 */ 54 55 LIST_HEAD(udv_list_struct, uvm_device); 56 static struct udv_list_struct udv_list; 57 static kmutex_t udv_lock; 58 59 /* 60 * functions 61 */ 62 63 static void udv_init(void); 64 static void udv_reference(struct uvm_object *); 65 static void udv_detach(struct uvm_object *); 66 static int udv_fault(struct uvm_faultinfo *, vaddr_t, 67 struct vm_page **, int, int, vm_prot_t, 68 int); 69 70 /* 71 * master pager structure 72 */ 73 74 const struct uvm_pagerops uvm_deviceops = { 75 .pgo_init = udv_init, 76 .pgo_reference = udv_reference, 77 .pgo_detach = udv_detach, 78 .pgo_fault = udv_fault, 79 }; 80 81 /* 82 * the ops! 83 */ 84 85 /* 86 * udv_init 87 * 88 * init pager private data structures. 89 */ 90 91 static void 92 udv_init(void) 93 { 94 LIST_INIT(&udv_list); 95 mutex_init(&udv_lock, MUTEX_DEFAULT, IPL_NONE); 96 } 97 98 /* 99 * udv_attach 100 * 101 * get a VM object that is associated with a device. allocate a new 102 * one if needed. 103 * 104 * => caller must _not_ already be holding the lock on the uvm_object. 105 * => in fact, nothing should be locked so that we can sleep here. 106 */ 107 108 struct uvm_object * 109 udv_attach(void *arg, vm_prot_t accessprot, 110 voff_t off, /* used only for access check */ 111 vsize_t size /* used only for access check */) 112 { 113 dev_t device = *((dev_t *)arg); 114 struct uvm_device *udv, *lcv; 115 const struct cdevsw *cdev; 116 dev_type_mmap((*mapfn)); 117 118 UVMHIST_FUNC("udv_attach"); UVMHIST_CALLED(maphist); 119 120 UVMHIST_LOG(maphist, "(device=0x%x)", device,0,0,0); 121 122 /* 123 * before we do anything, ensure this device supports mmap 124 */ 125 126 cdev = cdevsw_lookup(device); 127 if (cdev == NULL) { 128 return (NULL); 129 } 130 mapfn = cdev->d_mmap; 131 if (mapfn == NULL || mapfn == nommap || mapfn == nullmmap) { 132 return(NULL); 133 } 134 135 /* 136 * Negative offsets on the object are not allowed. 137 */ 138 139 if ((cdev->d_flag & D_NEGOFFSAFE) == 0 && 140 off != UVM_UNKNOWN_OFFSET && off < 0) 141 return(NULL); 142 143 /* 144 * Check that the specified range of the device allows the 145 * desired protection. 146 * 147 * XXX assumes VM_PROT_* == PROT_* 148 * XXX clobbers off and size, but nothing else here needs them. 149 */ 150 151 while (size != 0) { 152 if (cdev_mmap(device, off, accessprot) == -1) { 153 return (NULL); 154 } 155 off += PAGE_SIZE; size -= PAGE_SIZE; 156 } 157 158 /* 159 * keep looping until we get it 160 */ 161 162 for (;;) { 163 164 /* 165 * first, attempt to find it on the main list 166 */ 167 168 mutex_enter(&udv_lock); 169 LIST_FOREACH(lcv, &udv_list, u_list) { 170 if (device == lcv->u_device) 171 break; 172 } 173 174 /* 175 * got it on main list. put a hold on it and unlock udv_lock. 176 */ 177 178 if (lcv) { 179 180 /* 181 * if someone else has a hold on it, sleep and start 182 * over again. 183 */ 184 185 if (lcv->u_flags & UVM_DEVICE_HOLD) { 186 lcv->u_flags |= UVM_DEVICE_WANTED; 187 UVM_UNLOCK_AND_WAIT(lcv, &udv_lock, false, 188 "udv_attach",0); 189 continue; 190 } 191 192 /* we are now holding it */ 193 lcv->u_flags |= UVM_DEVICE_HOLD; 194 mutex_exit(&udv_lock); 195 196 /* 197 * bump reference count, unhold, return. 198 */ 199 200 mutex_enter(&lcv->u_obj.vmobjlock); 201 lcv->u_obj.uo_refs++; 202 mutex_exit(&lcv->u_obj.vmobjlock); 203 204 mutex_enter(&udv_lock); 205 if (lcv->u_flags & UVM_DEVICE_WANTED) 206 wakeup(lcv); 207 lcv->u_flags &= ~(UVM_DEVICE_WANTED|UVM_DEVICE_HOLD); 208 mutex_exit(&udv_lock); 209 return(&lcv->u_obj); 210 } 211 212 /* 213 * did not find it on main list. need to malloc a new one. 214 */ 215 216 mutex_exit(&udv_lock); 217 /* NOTE: we could sleep in the following malloc() */ 218 udv = malloc(sizeof(*udv), M_TEMP, M_WAITOK); 219 mutex_enter(&udv_lock); 220 221 /* 222 * now we have to double check to make sure no one added it 223 * to the list while we were sleeping... 224 */ 225 226 LIST_FOREACH(lcv, &udv_list, u_list) { 227 if (device == lcv->u_device) 228 break; 229 } 230 231 /* 232 * did we lose a race to someone else? 233 * free our memory and retry. 234 */ 235 236 if (lcv) { 237 mutex_exit(&udv_lock); 238 free(udv, M_TEMP); 239 continue; 240 } 241 242 /* 243 * we have it! init the data structures, add to list 244 * and return. 245 */ 246 247 UVM_OBJ_INIT(&udv->u_obj, &uvm_deviceops, 1); 248 udv->u_flags = 0; 249 udv->u_device = device; 250 LIST_INSERT_HEAD(&udv_list, udv, u_list); 251 mutex_exit(&udv_lock); 252 return(&udv->u_obj); 253 } 254 /*NOTREACHED*/ 255 } 256 257 /* 258 * udv_reference 259 * 260 * add a reference to a VM object. Note that the reference count must 261 * already be one (the passed in reference) so there is no chance of the 262 * udv being released or locked out here. 263 * 264 * => caller must call with object unlocked. 265 */ 266 267 static void 268 udv_reference(struct uvm_object *uobj) 269 { 270 UVMHIST_FUNC("udv_reference"); UVMHIST_CALLED(maphist); 271 272 mutex_enter(&uobj->vmobjlock); 273 uobj->uo_refs++; 274 UVMHIST_LOG(maphist, "<- done (uobj=0x%x, ref = %d)", 275 uobj, uobj->uo_refs,0,0); 276 mutex_exit(&uobj->vmobjlock); 277 } 278 279 /* 280 * udv_detach 281 * 282 * remove a reference to a VM object. 283 * 284 * => caller must call with object unlocked and map locked. 285 */ 286 287 static void 288 udv_detach(struct uvm_object *uobj) 289 { 290 struct uvm_device *udv = (struct uvm_device *)uobj; 291 UVMHIST_FUNC("udv_detach"); UVMHIST_CALLED(maphist); 292 293 /* 294 * loop until done 295 */ 296 again: 297 mutex_enter(&uobj->vmobjlock); 298 if (uobj->uo_refs > 1) { 299 uobj->uo_refs--; 300 mutex_exit(&uobj->vmobjlock); 301 UVMHIST_LOG(maphist," <- done, uobj=0x%x, ref=%d", 302 uobj,uobj->uo_refs,0,0); 303 return; 304 } 305 306 /* 307 * is it being held? if so, wait until others are done. 308 */ 309 310 mutex_enter(&udv_lock); 311 if (udv->u_flags & UVM_DEVICE_HOLD) { 312 udv->u_flags |= UVM_DEVICE_WANTED; 313 mutex_exit(&uobj->vmobjlock); 314 UVM_UNLOCK_AND_WAIT(udv, &udv_lock, false, "udv_detach",0); 315 goto again; 316 } 317 318 /* 319 * got it! nuke it now. 320 */ 321 322 LIST_REMOVE(udv, u_list); 323 if (udv->u_flags & UVM_DEVICE_WANTED) 324 wakeup(udv); 325 mutex_exit(&udv_lock); 326 mutex_exit(&uobj->vmobjlock); 327 UVM_OBJ_DESTROY(uobj); 328 free(udv, M_TEMP); 329 UVMHIST_LOG(maphist," <- done, freed uobj=0x%x", uobj,0,0,0); 330 } 331 332 /* 333 * udv_fault: non-standard fault routine for device "pages" 334 * 335 * => rather than having a "get" function, we have a fault routine 336 * since we don't return vm_pages we need full control over the 337 * pmap_enter map in 338 * => all the usual fault data structured are locked by the caller 339 * (i.e. maps(read), amap (if any), uobj) 340 * => on return, we unlock all fault data structures 341 * => flags: PGO_ALLPAGES: get all of the pages 342 * PGO_LOCKED: fault data structures are locked 343 * XXX: currently PGO_LOCKED is always required ... consider removing 344 * it as a flag 345 * => NOTE: vaddr is the VA of pps[0] in ufi->entry, _NOT_ pps[centeridx] 346 */ 347 348 static int 349 udv_fault(struct uvm_faultinfo *ufi, vaddr_t vaddr, struct vm_page **pps, 350 int npages, int centeridx, vm_prot_t access_type, 351 int flags) 352 { 353 struct vm_map_entry *entry = ufi->entry; 354 struct uvm_object *uobj = entry->object.uvm_obj; 355 struct uvm_device *udv = (struct uvm_device *)uobj; 356 vaddr_t curr_va; 357 off_t curr_offset; 358 paddr_t paddr, mdpgno; 359 u_int mmapflags; 360 int lcv, retval; 361 dev_t device; 362 vm_prot_t mapprot; 363 UVMHIST_FUNC("udv_fault"); UVMHIST_CALLED(maphist); 364 UVMHIST_LOG(maphist," flags=%d", flags,0,0,0); 365 366 /* 367 * we do not allow device mappings to be mapped copy-on-write 368 * so we kill any attempt to do so here. 369 */ 370 371 if (UVM_ET_ISCOPYONWRITE(entry)) { 372 UVMHIST_LOG(maphist, "<- failed -- COW entry (etype=0x%x)", 373 entry->etype, 0,0,0); 374 uvmfault_unlockall(ufi, ufi->entry->aref.ar_amap, uobj, NULL); 375 return(EIO); 376 } 377 378 /* 379 * get device map function. 380 */ 381 382 device = udv->u_device; 383 if (cdevsw_lookup(device) == NULL) { 384 /* XXX This should not happen */ 385 uvmfault_unlockall(ufi, ufi->entry->aref.ar_amap, uobj, NULL); 386 return (EIO); 387 } 388 389 /* 390 * now we must determine the offset in udv to use and the VA to 391 * use for pmap_enter. note that we always use orig_map's pmap 392 * for pmap_enter (even if we have a submap). since virtual 393 * addresses in a submap must match the main map, this is ok. 394 */ 395 396 /* udv offset = (offset from start of entry) + entry's offset */ 397 curr_offset = entry->offset + (vaddr - entry->start); 398 /* pmap va = vaddr (virtual address of pps[0]) */ 399 curr_va = vaddr; 400 401 /* 402 * loop over the page range entering in as needed 403 */ 404 405 retval = 0; 406 for (lcv = 0 ; lcv < npages ; lcv++, curr_offset += PAGE_SIZE, 407 curr_va += PAGE_SIZE) { 408 if ((flags & PGO_ALLPAGES) == 0 && lcv != centeridx) 409 continue; 410 411 if (pps[lcv] == PGO_DONTCARE) 412 continue; 413 414 mdpgno = cdev_mmap(device, curr_offset, access_type); 415 if (mdpgno == -1) { 416 retval = EIO; 417 break; 418 } 419 paddr = pmap_phys_address(mdpgno); 420 mmapflags = pmap_mmap_flags(mdpgno); 421 mapprot = ufi->entry->protection; 422 UVMHIST_LOG(maphist, 423 " MAPPING: device: pm=0x%x, va=0x%x, pa=0x%lx, at=%d", 424 ufi->orig_map->pmap, curr_va, paddr, mapprot); 425 if (pmap_enter(ufi->orig_map->pmap, curr_va, paddr, mapprot, 426 PMAP_CANFAIL | mapprot | mmapflags) != 0) { 427 /* 428 * pmap_enter() didn't have the resource to 429 * enter this mapping. Unlock everything, 430 * wait for the pagedaemon to free up some 431 * pages, and then tell uvm_fault() to start 432 * the fault again. 433 * 434 * XXX Needs some rethinking for the PGO_ALLPAGES 435 * XXX case. 436 */ 437 pmap_update(ufi->orig_map->pmap); /* sync what we have so far */ 438 uvmfault_unlockall(ufi, ufi->entry->aref.ar_amap, 439 uobj, NULL); 440 uvm_wait("udv_fault"); 441 return (ERESTART); 442 } 443 } 444 445 pmap_update(ufi->orig_map->pmap); 446 uvmfault_unlockall(ufi, ufi->entry->aref.ar_amap, uobj, NULL); 447 return (retval); 448 } 449