1 /* $NetBSD: uvm_device.c,v 1.63 2012/01/27 19:48:41 para 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 1.63 2012/01/27 19:48:41 para 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/kmem.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 allocate a new one. 214 */ 215 216 mutex_exit(&udv_lock); 217 218 /* Note: both calls may allocate memory and sleep. */ 219 udv = kmem_alloc(sizeof(*udv), KM_SLEEP); 220 uvm_obj_init(&udv->u_obj, &uvm_deviceops, true, 1); 221 222 mutex_enter(&udv_lock); 223 224 /* 225 * now we have to double check to make sure no one added it 226 * to the list while we were sleeping... 227 */ 228 229 LIST_FOREACH(lcv, &udv_list, u_list) { 230 if (device == lcv->u_device) 231 break; 232 } 233 234 /* 235 * did we lose a race to someone else? 236 * free our memory and retry. 237 */ 238 239 if (lcv) { 240 mutex_exit(&udv_lock); 241 uvm_obj_destroy(&udv->u_obj, true); 242 kmem_free(udv, sizeof(*udv)); 243 continue; 244 } 245 246 /* 247 * we have it! init the data structures, add to list 248 * and return. 249 */ 250 251 udv->u_flags = 0; 252 udv->u_device = device; 253 LIST_INSERT_HEAD(&udv_list, udv, u_list); 254 mutex_exit(&udv_lock); 255 return(&udv->u_obj); 256 } 257 /*NOTREACHED*/ 258 } 259 260 /* 261 * udv_reference 262 * 263 * add a reference to a VM object. Note that the reference count must 264 * already be one (the passed in reference) so there is no chance of the 265 * udv being released or locked out here. 266 * 267 * => caller must call with object unlocked. 268 */ 269 270 static void 271 udv_reference(struct uvm_object *uobj) 272 { 273 UVMHIST_FUNC("udv_reference"); UVMHIST_CALLED(maphist); 274 275 mutex_enter(uobj->vmobjlock); 276 uobj->uo_refs++; 277 UVMHIST_LOG(maphist, "<- done (uobj=0x%x, ref = %d)", 278 uobj, uobj->uo_refs,0,0); 279 mutex_exit(uobj->vmobjlock); 280 } 281 282 /* 283 * udv_detach 284 * 285 * remove a reference to a VM object. 286 * 287 * => caller must call with object unlocked and map locked. 288 */ 289 290 static void 291 udv_detach(struct uvm_object *uobj) 292 { 293 struct uvm_device *udv = (struct uvm_device *)uobj; 294 UVMHIST_FUNC("udv_detach"); UVMHIST_CALLED(maphist); 295 296 /* 297 * loop until done 298 */ 299 again: 300 mutex_enter(uobj->vmobjlock); 301 if (uobj->uo_refs > 1) { 302 uobj->uo_refs--; 303 mutex_exit(uobj->vmobjlock); 304 UVMHIST_LOG(maphist," <- done, uobj=0x%x, ref=%d", 305 uobj,uobj->uo_refs,0,0); 306 return; 307 } 308 309 /* 310 * is it being held? if so, wait until others are done. 311 */ 312 313 mutex_enter(&udv_lock); 314 if (udv->u_flags & UVM_DEVICE_HOLD) { 315 udv->u_flags |= UVM_DEVICE_WANTED; 316 mutex_exit(uobj->vmobjlock); 317 UVM_UNLOCK_AND_WAIT(udv, &udv_lock, false, "udv_detach",0); 318 goto again; 319 } 320 321 /* 322 * got it! nuke it now. 323 */ 324 325 LIST_REMOVE(udv, u_list); 326 if (udv->u_flags & UVM_DEVICE_WANTED) 327 wakeup(udv); 328 mutex_exit(&udv_lock); 329 mutex_exit(uobj->vmobjlock); 330 331 uvm_obj_destroy(uobj, true); 332 kmem_free(udv, sizeof(*udv)); 333 UVMHIST_LOG(maphist," <- done, freed uobj=0x%x", uobj,0,0,0); 334 } 335 336 /* 337 * udv_fault: non-standard fault routine for device "pages" 338 * 339 * => rather than having a "get" function, we have a fault routine 340 * since we don't return vm_pages we need full control over the 341 * pmap_enter map in 342 * => all the usual fault data structured are locked by the caller 343 * (i.e. maps(read), amap (if any), uobj) 344 * => on return, we unlock all fault data structures 345 * => flags: PGO_ALLPAGES: get all of the pages 346 * PGO_LOCKED: fault data structures are locked 347 * XXX: currently PGO_LOCKED is always required ... consider removing 348 * it as a flag 349 * => NOTE: vaddr is the VA of pps[0] in ufi->entry, _NOT_ pps[centeridx] 350 */ 351 352 static int 353 udv_fault(struct uvm_faultinfo *ufi, vaddr_t vaddr, struct vm_page **pps, 354 int npages, int centeridx, vm_prot_t access_type, 355 int flags) 356 { 357 struct vm_map_entry *entry = ufi->entry; 358 struct uvm_object *uobj = entry->object.uvm_obj; 359 struct uvm_device *udv = (struct uvm_device *)uobj; 360 vaddr_t curr_va; 361 off_t curr_offset; 362 paddr_t paddr, mdpgno; 363 u_int mmapflags; 364 int lcv, retval; 365 dev_t device; 366 vm_prot_t mapprot; 367 UVMHIST_FUNC("udv_fault"); UVMHIST_CALLED(maphist); 368 UVMHIST_LOG(maphist," flags=%d", flags,0,0,0); 369 370 /* 371 * we do not allow device mappings to be mapped copy-on-write 372 * so we kill any attempt to do so here. 373 */ 374 375 if (UVM_ET_ISCOPYONWRITE(entry)) { 376 UVMHIST_LOG(maphist, "<- failed -- COW entry (etype=0x%x)", 377 entry->etype, 0,0,0); 378 uvmfault_unlockall(ufi, ufi->entry->aref.ar_amap, uobj); 379 return(EIO); 380 } 381 382 /* 383 * get device map function. 384 */ 385 386 device = udv->u_device; 387 if (cdevsw_lookup(device) == NULL) { 388 /* XXX This should not happen */ 389 uvmfault_unlockall(ufi, ufi->entry->aref.ar_amap, uobj); 390 return (EIO); 391 } 392 393 /* 394 * now we must determine the offset in udv to use and the VA to 395 * use for pmap_enter. note that we always use orig_map's pmap 396 * for pmap_enter (even if we have a submap). since virtual 397 * addresses in a submap must match the main map, this is ok. 398 */ 399 400 /* udv offset = (offset from start of entry) + entry's offset */ 401 curr_offset = entry->offset + (vaddr - entry->start); 402 /* pmap va = vaddr (virtual address of pps[0]) */ 403 curr_va = vaddr; 404 405 /* 406 * loop over the page range entering in as needed 407 */ 408 409 retval = 0; 410 for (lcv = 0 ; lcv < npages ; lcv++, curr_offset += PAGE_SIZE, 411 curr_va += PAGE_SIZE) { 412 if ((flags & PGO_ALLPAGES) == 0 && lcv != centeridx) 413 continue; 414 415 if (pps[lcv] == PGO_DONTCARE) 416 continue; 417 418 mdpgno = cdev_mmap(device, curr_offset, access_type); 419 if (mdpgno == -1) { 420 retval = EIO; 421 break; 422 } 423 paddr = pmap_phys_address(mdpgno); 424 mmapflags = pmap_mmap_flags(mdpgno); 425 mapprot = ufi->entry->protection; 426 UVMHIST_LOG(maphist, 427 " MAPPING: device: pm=0x%x, va=0x%x, pa=0x%lx, at=%d", 428 ufi->orig_map->pmap, curr_va, paddr, mapprot); 429 if (pmap_enter(ufi->orig_map->pmap, curr_va, paddr, mapprot, 430 PMAP_CANFAIL | mapprot | mmapflags) != 0) { 431 /* 432 * pmap_enter() didn't have the resource to 433 * enter this mapping. Unlock everything, 434 * wait for the pagedaemon to free up some 435 * pages, and then tell uvm_fault() to start 436 * the fault again. 437 * 438 * XXX Needs some rethinking for the PGO_ALLPAGES 439 * XXX case. 440 */ 441 pmap_update(ufi->orig_map->pmap); /* sync what we have so far */ 442 uvmfault_unlockall(ufi, ufi->entry->aref.ar_amap, 443 uobj); 444 uvm_wait("udv_fault"); 445 return (ERESTART); 446 } 447 } 448 449 pmap_update(ufi->orig_map->pmap); 450 uvmfault_unlockall(ufi, ufi->entry->aref.ar_amap, uobj); 451 return (retval); 452 } 453