1 /* $OpenBSD: uvm_device.c,v 1.64 2021/06/29 01:46:35 jsg Exp $ */ 2 /* $NetBSD: uvm_device.c,v 1.30 2000/11/25 06:27:59 chs Exp $ */ 3 4 /* 5 * Copyright (c) 1997 Charles D. Cranor and Washington University. 6 * All rights reserved. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 18 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 19 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 20 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 21 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 22 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 27 * 28 * from: Id: uvm_device.c,v 1.1.2.9 1998/02/06 05:11:47 chs Exp 29 */ 30 31 /* 32 * uvm_device.c: the device pager. 33 */ 34 35 #include <sys/param.h> 36 #include <sys/systm.h> 37 #include <sys/conf.h> 38 #include <sys/malloc.h> 39 #include <sys/mutex.h> 40 41 #include <uvm/uvm.h> 42 #include <uvm/uvm_device.h> 43 44 #include "drm.h" 45 46 /* 47 * private global data structure 48 * 49 * we keep a list of active device objects in the system. 50 */ 51 52 LIST_HEAD(, uvm_device) udv_list = LIST_HEAD_INITIALIZER(udv_list); 53 struct mutex udv_lock = MUTEX_INITIALIZER(IPL_NONE); 54 55 /* 56 * functions 57 */ 58 static void udv_reference(struct uvm_object *); 59 static void udv_detach(struct uvm_object *); 60 static int udv_fault(struct uvm_faultinfo *, vaddr_t, 61 vm_page_t *, int, int, vm_fault_t, 62 vm_prot_t, int); 63 static boolean_t udv_flush(struct uvm_object *, voff_t, voff_t, 64 int); 65 66 /* 67 * master pager structure 68 */ 69 const struct uvm_pagerops uvm_deviceops = { 70 .pgo_reference = udv_reference, 71 .pgo_detach = udv_detach, 72 .pgo_fault = udv_fault, 73 .pgo_flush = udv_flush, 74 }; 75 76 /* 77 * the ops! 78 */ 79 80 81 /* 82 * udv_attach 83 * 84 * get a VM object that is associated with a device. allocate a new 85 * one if needed. 86 * 87 * => nothing should be locked so that we can sleep here. 88 * 89 * The last two arguments (off and size) are only used for access checking. 90 */ 91 struct uvm_object * 92 udv_attach(dev_t device, vm_prot_t accessprot, voff_t off, vsize_t size) 93 { 94 struct uvm_device *udv, *lcv; 95 paddr_t (*mapfn)(dev_t, off_t, int); 96 #if NDRM > 0 97 struct uvm_object *obj; 98 #endif 99 100 /* 101 * before we do anything, ensure this device supports mmap 102 */ 103 mapfn = cdevsw[major(device)].d_mmap; 104 if (mapfn == NULL || 105 mapfn == (paddr_t (*)(dev_t, off_t, int)) enodev || 106 mapfn == (paddr_t (*)(dev_t, off_t, int)) nullop) 107 return(NULL); 108 109 /* 110 * Negative offsets on the object are not allowed. 111 */ 112 if (off < 0) 113 return(NULL); 114 115 #if NDRM > 0 116 obj = udv_attach_drm(device, accessprot, off, size); 117 if (obj) 118 return(obj); 119 #endif 120 121 /* 122 * Check that the specified range of the device allows the 123 * desired protection. 124 * 125 * XXX clobbers off and size, but nothing else here needs them. 126 */ 127 while (size != 0) { 128 if ((*mapfn)(device, off, accessprot) == -1) 129 return (NULL); 130 off += PAGE_SIZE; size -= PAGE_SIZE; 131 } 132 133 /* 134 * keep looping until we get it 135 */ 136 for (;;) { 137 /* 138 * first, attempt to find it on the main list 139 */ 140 mtx_enter(&udv_lock); 141 LIST_FOREACH(lcv, &udv_list, u_list) { 142 if (device == lcv->u_device) 143 break; 144 } 145 146 /* 147 * got it on main list. put a hold on it and unlock udv_lock. 148 */ 149 if (lcv) { 150 /* 151 * if someone else has a hold on it, sleep and start 152 * over again. Else, we need take HOLD flag so we 153 * don't have to re-order locking here. 154 */ 155 if (lcv->u_flags & UVM_DEVICE_HOLD) { 156 lcv->u_flags |= UVM_DEVICE_WANTED; 157 msleep_nsec(lcv, &udv_lock, PVM | PNORELOCK, 158 "udv_attach", INFSLP); 159 continue; 160 } 161 162 /* we are now holding it */ 163 lcv->u_flags |= UVM_DEVICE_HOLD; 164 mtx_leave(&udv_lock); 165 166 /* 167 * bump reference count, unhold, return. 168 */ 169 lcv->u_obj.uo_refs++; 170 171 mtx_enter(&udv_lock); 172 if (lcv->u_flags & UVM_DEVICE_WANTED) 173 wakeup(lcv); 174 lcv->u_flags &= ~(UVM_DEVICE_WANTED|UVM_DEVICE_HOLD); 175 mtx_leave(&udv_lock); 176 return(&lcv->u_obj); 177 } 178 179 /* 180 * Did not find it on main list. Need to allocate a new one. 181 */ 182 mtx_leave(&udv_lock); 183 /* NOTE: we could sleep in the following malloc() */ 184 udv = malloc(sizeof(*udv), M_TEMP, M_WAITOK); 185 mtx_enter(&udv_lock); 186 187 /* 188 * now we have to double check to make sure no one added it 189 * to the list while we were sleeping... 190 */ 191 LIST_FOREACH(lcv, &udv_list, u_list) { 192 if (device == lcv->u_device) 193 break; 194 } 195 196 /* 197 * did we lose a race to someone else? 198 * free our memory and retry. 199 */ 200 if (lcv) { 201 mtx_leave(&udv_lock); 202 free(udv, M_TEMP, sizeof(*udv)); 203 continue; 204 } 205 206 /* 207 * we have it! init the data structures, add to list 208 * and return. 209 */ 210 uvm_obj_init(&udv->u_obj, &uvm_deviceops, 1); 211 udv->u_flags = 0; 212 udv->u_device = device; 213 LIST_INSERT_HEAD(&udv_list, udv, u_list); 214 mtx_leave(&udv_lock); 215 return(&udv->u_obj); 216 } 217 /*NOTREACHED*/ 218 } 219 220 /* 221 * udv_reference 222 * 223 * add a reference to a VM object. Note that the reference count must 224 * already be one (the passed in reference) so there is no chance of the 225 * udv being released or locked out here. 226 */ 227 static void 228 udv_reference(struct uvm_object *uobj) 229 { 230 KERNEL_ASSERT_LOCKED(); 231 uobj->uo_refs++; 232 } 233 234 /* 235 * udv_detach 236 * 237 * remove a reference to a VM object. 238 */ 239 static void 240 udv_detach(struct uvm_object *uobj) 241 { 242 struct uvm_device *udv = (struct uvm_device *)uobj; 243 244 KERNEL_ASSERT_LOCKED(); 245 246 /* 247 * loop until done 248 */ 249 again: 250 if (uobj->uo_refs > 1) { 251 uobj->uo_refs--; 252 return; 253 } 254 KASSERT(uobj->uo_npages == 0 && RBT_EMPTY(uvm_objtree, &uobj->memt)); 255 256 /* 257 * is it being held? if so, wait until others are done. 258 */ 259 mtx_enter(&udv_lock); 260 if (udv->u_flags & UVM_DEVICE_HOLD) { 261 udv->u_flags |= UVM_DEVICE_WANTED; 262 /* 263 * lock interleaving. -- this is ok in this case since the 264 * locks are both IPL_NONE 265 */ 266 msleep_nsec(udv, &udv_lock, PVM | PNORELOCK, "udv_detach", 267 INFSLP); 268 goto again; 269 } 270 271 /* 272 * got it! nuke it now. 273 */ 274 LIST_REMOVE(udv, u_list); 275 if (udv->u_flags & UVM_DEVICE_WANTED) 276 wakeup(udv); 277 mtx_leave(&udv_lock); 278 free(udv, M_TEMP, sizeof(*udv)); 279 } 280 281 282 /* 283 * udv_flush 284 * 285 * flush pages out of a uvm object. a no-op for devices. 286 */ 287 static boolean_t 288 udv_flush(struct uvm_object *uobj, voff_t start, voff_t stop, int flags) 289 { 290 291 return(TRUE); 292 } 293 294 /* 295 * udv_fault: non-standard fault routine for device "pages" 296 * 297 * => rather than having a "get" function, we have a fault routine 298 * since we don't return vm_pages we need full control over the 299 * pmap_enter map in 300 * => on return, we unlock all fault data structures 301 * => flags: PGO_ALLPAGES: get all of the pages 302 * PGO_LOCKED: fault data structures are locked 303 * XXX: currently PGO_LOCKED is always required ... consider removing 304 * it as a flag 305 * => NOTE: vaddr is the VA of pps[0] in ufi->entry, _NOT_ pps[centeridx] 306 */ 307 static int 308 udv_fault(struct uvm_faultinfo *ufi, vaddr_t vaddr, vm_page_t *pps, int npages, 309 int centeridx, vm_fault_t fault_type, vm_prot_t access_type, int flags) 310 { 311 struct vm_map_entry *entry = ufi->entry; 312 struct uvm_object *uobj = entry->object.uvm_obj; 313 struct uvm_device *udv = (struct uvm_device *)uobj; 314 vaddr_t curr_va; 315 off_t curr_offset; 316 paddr_t paddr; 317 int lcv, retval; 318 dev_t device; 319 paddr_t (*mapfn)(dev_t, off_t, int); 320 vm_prot_t mapprot; 321 322 KERNEL_ASSERT_LOCKED(); 323 324 /* 325 * we do not allow device mappings to be mapped copy-on-write 326 * so we kill any attempt to do so here. 327 */ 328 if (UVM_ET_ISCOPYONWRITE(entry)) { 329 uvmfault_unlockall(ufi, ufi->entry->aref.ar_amap, uobj); 330 return(VM_PAGER_ERROR); 331 } 332 333 /* 334 * get device map function. 335 */ 336 device = udv->u_device; 337 mapfn = cdevsw[major(device)].d_mmap; 338 339 /* 340 * now we must determine the offset in udv to use and the VA to 341 * use for pmap_enter. note that we always use orig_map's pmap 342 * for pmap_enter (even if we have a submap). since virtual 343 * addresses in a submap must match the main map, this is ok. 344 */ 345 /* udv offset = (offset from start of entry) + entry's offset */ 346 curr_offset = entry->offset + (vaddr - entry->start); 347 /* pmap va = vaddr (virtual address of pps[0]) */ 348 curr_va = vaddr; 349 350 /* 351 * loop over the page range entering in as needed 352 */ 353 retval = VM_PAGER_OK; 354 for (lcv = 0 ; lcv < npages ; lcv++, curr_offset += PAGE_SIZE, 355 curr_va += PAGE_SIZE) { 356 if ((flags & PGO_ALLPAGES) == 0 && lcv != centeridx) 357 continue; 358 359 if (pps[lcv] == PGO_DONTCARE) 360 continue; 361 362 paddr = (*mapfn)(device, curr_offset, access_type); 363 if (paddr == -1) { 364 retval = VM_PAGER_ERROR; 365 break; 366 } 367 mapprot = ufi->entry->protection; 368 if (pmap_enter(ufi->orig_map->pmap, curr_va, paddr, 369 mapprot, PMAP_CANFAIL | mapprot) != 0) { 370 /* 371 * pmap_enter() didn't have the resource to 372 * enter this mapping. Unlock everything, 373 * wait for the pagedaemon to free up some 374 * pages, and then tell uvm_fault() to start 375 * the fault again. 376 * 377 * XXX Needs some rethinking for the PGO_ALLPAGES 378 * XXX case. 379 */ 380 uvmfault_unlockall(ufi, ufi->entry->aref.ar_amap, 381 uobj); 382 383 /* sync what we have so far */ 384 pmap_update(ufi->orig_map->pmap); 385 uvm_wait("udv_fault"); 386 return (VM_PAGER_REFAULT); 387 } 388 } 389 390 uvmfault_unlockall(ufi, ufi->entry->aref.ar_amap, uobj); 391 pmap_update(ufi->orig_map->pmap); 392 return (retval); 393 } 394