uvm_device.c revision 1.71
1 /* $NetBSD: uvm_device.c,v 1.71 2020/07/09 05:57:15 skrll 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 1.71 2020/07/09 05:57:15 skrll 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 __cacheline_aligned; 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(__func__); 118 UVMHIST_CALLARGS(maphist, "(device=%#jx)", device,0,0,0); 119 120 /* 121 * before we do anything, ensure this device supports mmap 122 */ 123 124 cdev = cdevsw_lookup(device); 125 if (cdev == NULL) { 126 return (NULL); 127 } 128 mapfn = cdev->d_mmap; 129 if (mapfn == NULL || mapfn == nommap) { 130 return(NULL); 131 } 132 133 /* 134 * Negative offsets on the object are not allowed. 135 */ 136 137 if ((cdev->d_flag & D_NEGOFFSAFE) == 0 && 138 off != UVM_UNKNOWN_OFFSET && off < 0) 139 return(NULL); 140 141 /* 142 * Check that the specified range of the device allows the 143 * desired protection. 144 * 145 * XXX assumes VM_PROT_* == PROT_* 146 * XXX clobbers off and size, but nothing else here needs them. 147 */ 148 149 while (size != 0) { 150 if (cdev_mmap(device, off, accessprot) == -1) { 151 return (NULL); 152 } 153 off += PAGE_SIZE; size -= PAGE_SIZE; 154 } 155 156 /* 157 * keep looping until we get it 158 */ 159 160 for (;;) { 161 162 /* 163 * first, attempt to find it on the main list 164 */ 165 166 mutex_enter(&udv_lock); 167 LIST_FOREACH(lcv, &udv_list, u_list) { 168 if (device == lcv->u_device) 169 break; 170 } 171 172 /* 173 * got it on main list. put a hold on it and unlock udv_lock. 174 */ 175 176 if (lcv) { 177 178 /* 179 * if someone else has a hold on it, sleep and start 180 * over again. 181 */ 182 183 if (lcv->u_flags & UVM_DEVICE_HOLD) { 184 lcv->u_flags |= UVM_DEVICE_WANTED; 185 UVM_UNLOCK_AND_WAIT(lcv, &udv_lock, false, 186 "udv_attach",0); 187 continue; 188 } 189 190 /* we are now holding it */ 191 lcv->u_flags |= UVM_DEVICE_HOLD; 192 mutex_exit(&udv_lock); 193 194 /* 195 * bump reference count, unhold, return. 196 */ 197 198 rw_enter(lcv->u_obj.vmobjlock, RW_WRITER); 199 lcv->u_obj.uo_refs++; 200 rw_exit(lcv->u_obj.vmobjlock); 201 202 mutex_enter(&udv_lock); 203 if (lcv->u_flags & UVM_DEVICE_WANTED) 204 wakeup(lcv); 205 lcv->u_flags &= ~(UVM_DEVICE_WANTED|UVM_DEVICE_HOLD); 206 mutex_exit(&udv_lock); 207 return(&lcv->u_obj); 208 } 209 210 /* 211 * Did not find it on main list. Need to allocate a new one. 212 */ 213 214 mutex_exit(&udv_lock); 215 216 /* Note: both calls may allocate memory and sleep. */ 217 udv = kmem_alloc(sizeof(*udv), KM_SLEEP); 218 uvm_obj_init(&udv->u_obj, &uvm_deviceops, true, 1); 219 220 mutex_enter(&udv_lock); 221 222 /* 223 * now we have to double check to make sure no one added it 224 * to the list while we were sleeping... 225 */ 226 227 LIST_FOREACH(lcv, &udv_list, u_list) { 228 if (device == lcv->u_device) 229 break; 230 } 231 232 /* 233 * did we lose a race to someone else? 234 * free our memory and retry. 235 */ 236 237 if (lcv) { 238 mutex_exit(&udv_lock); 239 uvm_obj_destroy(&udv->u_obj, true); 240 kmem_free(udv, sizeof(*udv)); 241 continue; 242 } 243 244 /* 245 * we have it! init the data structures, add to list 246 * and return. 247 */ 248 249 udv->u_flags = 0; 250 udv->u_device = device; 251 LIST_INSERT_HEAD(&udv_list, udv, u_list); 252 mutex_exit(&udv_lock); 253 return(&udv->u_obj); 254 } 255 /*NOTREACHED*/ 256 } 257 258 /* 259 * udv_reference 260 * 261 * add a reference to a VM object. Note that the reference count must 262 * already be one (the passed in reference) so there is no chance of the 263 * udv being released or locked out here. 264 * 265 * => caller must call with object unlocked. 266 */ 267 268 static void 269 udv_reference(struct uvm_object *uobj) 270 { 271 UVMHIST_FUNC(__func__); UVMHIST_CALLED(maphist); 272 273 rw_enter(uobj->vmobjlock, RW_WRITER); 274 uobj->uo_refs++; 275 UVMHIST_LOG(maphist, "<- done (uobj=%#jx, ref = %jd)", 276 (uintptr_t)uobj, uobj->uo_refs,0,0); 277 rw_exit(uobj->vmobjlock); 278 } 279 280 /* 281 * udv_detach 282 * 283 * remove a reference to a VM object. 284 * 285 * => caller must call with object unlocked and map locked. 286 */ 287 288 static void 289 udv_detach(struct uvm_object *uobj) 290 { 291 struct uvm_device *udv = (struct uvm_device *)uobj; 292 UVMHIST_FUNC(__func__); UVMHIST_CALLED(maphist); 293 294 /* 295 * loop until done 296 */ 297 again: 298 rw_enter(uobj->vmobjlock, RW_WRITER); 299 if (uobj->uo_refs > 1) { 300 uobj->uo_refs--; 301 rw_exit(uobj->vmobjlock); 302 UVMHIST_LOG(maphist," <- done, uobj=%#jx, ref=%jd", 303 (uintptr_t)uobj,uobj->uo_refs,0,0); 304 return; 305 } 306 307 /* 308 * is it being held? if so, wait until others are done. 309 */ 310 311 mutex_enter(&udv_lock); 312 if (udv->u_flags & UVM_DEVICE_HOLD) { 313 udv->u_flags |= UVM_DEVICE_WANTED; 314 rw_exit(uobj->vmobjlock); 315 UVM_UNLOCK_AND_WAIT(udv, &udv_lock, false, "udv_detach",0); 316 goto again; 317 } 318 319 /* 320 * got it! nuke it now. 321 */ 322 323 LIST_REMOVE(udv, u_list); 324 if (udv->u_flags & UVM_DEVICE_WANTED) 325 wakeup(udv); 326 mutex_exit(&udv_lock); 327 rw_exit(uobj->vmobjlock); 328 329 uvm_obj_destroy(uobj, true); 330 kmem_free(udv, sizeof(*udv)); 331 UVMHIST_LOG(maphist," <- done, freed uobj=%#jx", (uintptr_t)uobj, 332 0, 0, 0); 333 } 334 335 /* 336 * udv_fault: non-standard fault routine for device "pages" 337 * 338 * => rather than having a "get" function, we have a fault routine 339 * since we don't return vm_pages we need full control over the 340 * pmap_enter map in 341 * => all the usual fault data structured are locked by the caller 342 * (i.e. maps(read), amap (if any), uobj) 343 * => on return, we unlock all fault data structures 344 * => flags: PGO_ALLPAGES: get all of the pages 345 * PGO_LOCKED: fault data structures are locked 346 * XXX: currently PGO_LOCKED is always required ... consider removing 347 * it as a flag 348 * => NOTE: vaddr is the VA of pps[0] in ufi->entry, _NOT_ pps[centeridx] 349 */ 350 351 static int 352 udv_fault(struct uvm_faultinfo *ufi, vaddr_t vaddr, struct vm_page **pps, 353 int npages, int centeridx, vm_prot_t access_type, 354 int flags) 355 { 356 struct vm_map_entry *entry = ufi->entry; 357 struct uvm_object *uobj = entry->object.uvm_obj; 358 struct uvm_device *udv = (struct uvm_device *)uobj; 359 vaddr_t curr_va; 360 off_t curr_offset; 361 paddr_t paddr, mdpgno; 362 u_int mmapflags; 363 int lcv, retval; 364 dev_t device; 365 vm_prot_t mapprot; 366 UVMHIST_FUNC(__func__); UVMHIST_CALLED(maphist); 367 UVMHIST_LOG(maphist," flags=%jd", flags,0,0,0); 368 369 /* 370 * we do not allow device mappings to be mapped copy-on-write 371 * so we kill any attempt to do so here. 372 */ 373 374 if (UVM_ET_ISCOPYONWRITE(entry)) { 375 UVMHIST_LOG(maphist, "<- failed -- COW entry (etype=%#jx)", 376 entry->etype, 0,0,0); 377 uvmfault_unlockall(ufi, ufi->entry->aref.ar_amap, uobj); 378 return(EIO); 379 } 380 381 /* 382 * get device map function. 383 */ 384 385 device = udv->u_device; 386 if (cdevsw_lookup(device) == NULL) { 387 /* XXX This should not happen */ 388 uvmfault_unlockall(ufi, ufi->entry->aref.ar_amap, uobj); 389 return (EIO); 390 } 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 = 0; 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 = cdev_mmap(device, curr_offset, access_type); 418 if (mdpgno == -1) { 419 retval = EIO; 420 break; 421 } 422 paddr = pmap_phys_address(mdpgno); 423 mmapflags = pmap_mmap_flags(mdpgno); 424 mapprot = ufi->entry->protection; 425 UVMHIST_LOG(maphist, 426 " MAPPING: device: pm=%#jx, va=%#jx, pa=%#jx, at=%jd", 427 (uintptr_t)ufi->orig_map->pmap, curr_va, paddr, mapprot); 428 if (pmap_enter(ufi->orig_map->pmap, curr_va, paddr, mapprot, 429 PMAP_CANFAIL | mapprot | mmapflags) != 0) { 430 /* 431 * pmap_enter() didn't have the resource to 432 * enter this mapping. Unlock everything, 433 * wait for the pagedaemon to free up some 434 * pages, and then tell uvm_fault() to start 435 * the fault again. 436 * 437 * XXX Needs some rethinking for the PGO_ALLPAGES 438 * XXX case. 439 */ 440 pmap_update(ufi->orig_map->pmap); /* sync what we have so far */ 441 uvmfault_unlockall(ufi, ufi->entry->aref.ar_amap, 442 uobj); 443 return ENOMEM; 444 } 445 } 446 447 pmap_update(ufi->orig_map->pmap); 448 uvmfault_unlockall(ufi, ufi->entry->aref.ar_amap, uobj); 449 return (retval); 450 } 451
Indexes created Tue Sep 30 10:09:55 GMT 2025