1 /* $NetBSD: uvm_device.c,v 1.66 2017/10/28 00:37:13 pgoyette 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 1.66 2017/10/28 00:37:13 pgoyette 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(dev_t device, vm_prot_t accessprot, 110 voff_t off, /* used only for access check */ 111 vsize_t size /* used only for access check */) 112 { 113 struct uvm_device *udv, *lcv; 114 const struct cdevsw *cdev; 115 dev_type_mmap((*mapfn)); 116 117 UVMHIST_FUNC("udv_attach"); UVMHIST_CALLED(maphist); 118 119 UVMHIST_LOG(maphist, "(device=0x%jx)", device,0,0,0); 120 121 /* 122 * before we do anything, ensure this device supports mmap 123 */ 124 125 cdev = cdevsw_lookup(device); 126 if (cdev == NULL) { 127 return (NULL); 128 } 129 mapfn = cdev->d_mmap; 130 if (mapfn == NULL || mapfn == nommap) { 131 return(NULL); 132 } 133 134 /* 135 * Negative offsets on the object are not allowed. 136 */ 137 138 if ((cdev->d_flag & D_NEGOFFSAFE) == 0 && 139 off != UVM_UNKNOWN_OFFSET && off < 0) 140 return(NULL); 141 142 /* 143 * Check that the specified range of the device allows the 144 * desired protection. 145 * 146 * XXX assumes VM_PROT_* == PROT_* 147 * XXX clobbers off and size, but nothing else here needs them. 148 */ 149 150 while (size != 0) { 151 if (cdev_mmap(device, off, accessprot) == -1) { 152 return (NULL); 153 } 154 off += PAGE_SIZE; size -= PAGE_SIZE; 155 } 156 157 /* 158 * keep looping until we get it 159 */ 160 161 for (;;) { 162 163 /* 164 * first, attempt to find it on the main list 165 */ 166 167 mutex_enter(&udv_lock); 168 LIST_FOREACH(lcv, &udv_list, u_list) { 169 if (device == lcv->u_device) 170 break; 171 } 172 173 /* 174 * got it on main list. put a hold on it and unlock udv_lock. 175 */ 176 177 if (lcv) { 178 179 /* 180 * if someone else has a hold on it, sleep and start 181 * over again. 182 */ 183 184 if (lcv->u_flags & UVM_DEVICE_HOLD) { 185 lcv->u_flags |= UVM_DEVICE_WANTED; 186 UVM_UNLOCK_AND_WAIT(lcv, &udv_lock, false, 187 "udv_attach",0); 188 continue; 189 } 190 191 /* we are now holding it */ 192 lcv->u_flags |= UVM_DEVICE_HOLD; 193 mutex_exit(&udv_lock); 194 195 /* 196 * bump reference count, unhold, return. 197 */ 198 199 mutex_enter(lcv->u_obj.vmobjlock); 200 lcv->u_obj.uo_refs++; 201 mutex_exit(lcv->u_obj.vmobjlock); 202 203 mutex_enter(&udv_lock); 204 if (lcv->u_flags & UVM_DEVICE_WANTED) 205 wakeup(lcv); 206 lcv->u_flags &= ~(UVM_DEVICE_WANTED|UVM_DEVICE_HOLD); 207 mutex_exit(&udv_lock); 208 return(&lcv->u_obj); 209 } 210 211 /* 212 * Did not find it on main list. Need to allocate a new one. 213 */ 214 215 mutex_exit(&udv_lock); 216 217 /* Note: both calls may allocate memory and sleep. */ 218 udv = kmem_alloc(sizeof(*udv), KM_SLEEP); 219 uvm_obj_init(&udv->u_obj, &uvm_deviceops, true, 1); 220 221 mutex_enter(&udv_lock); 222 223 /* 224 * now we have to double check to make sure no one added it 225 * to the list while we were sleeping... 226 */ 227 228 LIST_FOREACH(lcv, &udv_list, u_list) { 229 if (device == lcv->u_device) 230 break; 231 } 232 233 /* 234 * did we lose a race to someone else? 235 * free our memory and retry. 236 */ 237 238 if (lcv) { 239 mutex_exit(&udv_lock); 240 uvm_obj_destroy(&udv->u_obj, true); 241 kmem_free(udv, sizeof(*udv)); 242 continue; 243 } 244 245 /* 246 * we have it! init the data structures, add to list 247 * and return. 248 */ 249 250 udv->u_flags = 0; 251 udv->u_device = device; 252 LIST_INSERT_HEAD(&udv_list, udv, u_list); 253 mutex_exit(&udv_lock); 254 return(&udv->u_obj); 255 } 256 /*NOTREACHED*/ 257 } 258 259 /* 260 * udv_reference 261 * 262 * add a reference to a VM object. Note that the reference count must 263 * already be one (the passed in reference) so there is no chance of the 264 * udv being released or locked out here. 265 * 266 * => caller must call with object unlocked. 267 */ 268 269 static void 270 udv_reference(struct uvm_object *uobj) 271 { 272 UVMHIST_FUNC("udv_reference"); UVMHIST_CALLED(maphist); 273 274 mutex_enter(uobj->vmobjlock); 275 uobj->uo_refs++; 276 UVMHIST_LOG(maphist, "<- done (uobj=0x%#jx, ref = %jd)", 277 (uintptr_t)uobj, uobj->uo_refs,0,0); 278 mutex_exit(uobj->vmobjlock); 279 } 280 281 /* 282 * udv_detach 283 * 284 * remove a reference to a VM object. 285 * 286 * => caller must call with object unlocked and map locked. 287 */ 288 289 static void 290 udv_detach(struct uvm_object *uobj) 291 { 292 struct uvm_device *udv = (struct uvm_device *)uobj; 293 UVMHIST_FUNC("udv_detach"); UVMHIST_CALLED(maphist); 294 295 /* 296 * loop until done 297 */ 298 again: 299 mutex_enter(uobj->vmobjlock); 300 if (uobj->uo_refs > 1) { 301 uobj->uo_refs--; 302 mutex_exit(uobj->vmobjlock); 303 UVMHIST_LOG(maphist," <- done, uobj=0x%#jx, ref=%jd", 304 (uintptr_t)uobj,uobj->uo_refs,0,0); 305 return; 306 } 307 308 /* 309 * is it being held? if so, wait until others are done. 310 */ 311 312 mutex_enter(&udv_lock); 313 if (udv->u_flags & UVM_DEVICE_HOLD) { 314 udv->u_flags |= UVM_DEVICE_WANTED; 315 mutex_exit(uobj->vmobjlock); 316 UVM_UNLOCK_AND_WAIT(udv, &udv_lock, false, "udv_detach",0); 317 goto again; 318 } 319 320 /* 321 * got it! nuke it now. 322 */ 323 324 LIST_REMOVE(udv, u_list); 325 if (udv->u_flags & UVM_DEVICE_WANTED) 326 wakeup(udv); 327 mutex_exit(&udv_lock); 328 mutex_exit(uobj->vmobjlock); 329 330 uvm_obj_destroy(uobj, true); 331 kmem_free(udv, sizeof(*udv)); 332 UVMHIST_LOG(maphist," <- done, freed uobj=0x%#jx", (uintptr_t)uobj, 333 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=%jd", 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%jx)", 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%#jx, va=0x%jx, pa=0x%jx, at=%jd", 428 (uintptr_t)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