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--- old/usr/src/uts/common/os/vm_subr.c
+++ new/usr/src/uts/common/os/vm_subr.c
1 1 /*
2 2 * CDDL HEADER START
3 3 *
4 4 * The contents of this file are subject to the terms of the
5 5 * Common Development and Distribution License (the "License").
6 6 * You may not use this file except in compliance with the License.
7 7 *
8 8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 9 * or http://www.opensolaris.org/os/licensing.
10 10 * See the License for the specific language governing permissions
11 11 * and limitations under the License.
12 12 *
13 13 * When distributing Covered Code, include this CDDL HEADER in each
14 14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 15 * If applicable, add the following below this CDDL HEADER, with the
16 16 * fields enclosed by brackets "[]" replaced with your own identifying
17 17 * information: Portions Copyright [yyyy] [name of copyright owner]
18 18 *
19 19 * CDDL HEADER END
20 20 */
21 21 /*
22 22 * Copyright (c) 1986, 2010, Oracle and/or its affiliates. All rights reserved.
23 23 */
24 24
25 25 /* Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T */
26 26 /* All Rights Reserved */
27 27
28 28 /*
29 29 * University Copyright- Copyright (c) 1982, 1986, 1988
30 30 * The Regents of the University of California
31 31 * All Rights Reserved
32 32 *
33 33 * University Acknowledgment- Portions of this document are derived from
34 34 * software developed by the University of California, Berkeley, and its
35 35 * contributors.
36 36 */
37 37
38 38 #include <sys/types.h>
39 39 #include <sys/t_lock.h>
40 40 #include <sys/param.h>
41 41 #include <sys/errno.h>
42 42 #include <sys/debug.h>
43 43 #include <sys/cmn_err.h>
44 44 #include <sys/kmem.h>
45 45 #include <sys/sysmacros.h>
46 46 #include <sys/inline.h>
47 47 #include <sys/buf.h>
48 48 #include <sys/uio.h>
49 49 #include <sys/user.h>
50 50 #include <sys/proc.h>
51 51 #include <sys/systm.h>
52 52 #include <sys/vmsystm.h>
53 53 #include <sys/cpuvar.h>
54 54 #include <sys/mman.h>
55 55 #include <sys/cred.h>
56 56 #include <sys/vnode.h>
57 57 #include <sys/file.h>
58 58 #include <sys/vm.h>
59 59
60 60 #include <sys/swap.h>
61 61 #include <sys/vtrace.h>
62 62 #include <sys/tnf_probe.h>
63 63 #include <sys/fs/snode.h>
64 64 #include <sys/copyops.h>
65 65 #include <sys/conf.h>
66 66 #include <sys/sdt.h>
67 67
68 68 #include <vm/anon.h>
69 69 #include <vm/hat.h>
70 70 #include <vm/as.h>
71 71 #include <vm/seg.h>
72 72 #include <vm/page.h>
73 73 #include <vm/seg_vn.h>
74 74 #include <vm/seg_kmem.h>
75 75
76 76 extern int maxphys;
77 77
78 78 void
79 79 minphys(struct buf *bp)
80 80 {
81 81 if (bp->b_bcount > maxphys)
82 82 bp->b_bcount = maxphys;
83 83 }
84 84
85 85 /*
86 86 * use kmem_cache_create for physio buffers. This has shown
87 87 * a better cache distribution compared to buffers on the
88 88 * stack. It also avoids semaphore construction/deconstruction
89 89 * per request
90 90 */
91 91
92 92 static struct kmem_cache *physio_buf_cache;
93 93
94 94 /* ARGSUSED */
95 95 static int
96 96 physio_buf_constructor(void *buf, void *cdrarg, int kmflags)
97 97 {
98 98 bioinit((struct buf *)buf);
99 99 return (0);
100 100 }
101 101
102 102 /* ARGSUSED */
103 103 static void
104 104 physio_buf_destructor(void *buf, void *cdrarg)
105 105 {
106 106 biofini((struct buf *)buf);
107 107 }
108 108
109 109 void
110 110 physio_bufs_init(void)
111 111 {
112 112 physio_buf_cache = kmem_cache_create("physio_buf_cache",
113 113 sizeof (struct buf), 0, physio_buf_constructor,
114 114 physio_buf_destructor, NULL, NULL, NULL, 0);
115 115 }
116 116
117 117
118 118
119 119 /*
120 120 * initiate raw I/O request
121 121 *
122 122 * allocate buf header if necessary
123 123 * adjust max size of each I/O request
124 124 * lock down user pages and verify access protections
125 125 * call driver's strategy routine to submit request
126 126 * wait for I/O completion
127 127 * unlock user pages and free allocated buf header
128 128 */
129 129
130 130 int
131 131 default_physio(int (*strat)(struct buf *), struct buf *bp, dev_t dev,
132 132 int rw, void (*mincnt)(struct buf *), struct uio *uio)
133 133 {
134 134 struct iovec *iov;
135 135 struct proc *procp;
136 136 struct as *asp;
137 137 ssize_t c;
138 138 char *a;
139 139 int error = 0;
140 140 page_t **pplist;
141 141 int allocbuf = 0;
142 142
143 143 TRACE_1(TR_FAC_PHYSIO, TR_PHYSIO_START, "physio_start: bp %p", bp);
144 144
145 145 /* Kernel probe */
146 146 TNF_PROBE_4(physio_start, "io rawio", /* CSTYLED */,
147 147 tnf_device, device, dev,
148 148 tnf_offset, offset, uio->uio_loffset,
149 149 tnf_size, size, uio->uio_resid,
150 150 tnf_bioflags, rw, rw);
151 151
152 152 if (rw == B_READ) {
153 153 CPU_STATS_ADD_K(sys, phread, 1);
154 154 } else {
155 155 CPU_STATS_ADD_K(sys, phwrite, 1);
156 156 }
157 157
158 158 TRACE_1(TR_FAC_PHYSIO, TR_PHYSIO_GETBUF_START,
159 159 "getbuf_start: bp %p", bp);
160 160
161 161 if (bp == NULL) {
162 162 bp = kmem_cache_alloc(physio_buf_cache, KM_SLEEP);
163 163 bp->b_iodone = NULL;
164 164 bp->b_resid = 0;
165 165 allocbuf = 1;
166 166 }
167 167 TRACE_1(TR_FAC_PHYSIO, TR_PHYSIO_GETBUF_END, "getbuf_end: bp %p", bp);
168 168
169 169 if (uio->uio_segflg == UIO_USERSPACE) {
170 170 procp = ttoproc(curthread);
171 171 asp = procp->p_as;
172 172 } else {
173 173 procp = NULL;
174 174 asp = &kas;
175 175 }
176 176 ASSERT(SEMA_HELD(&bp->b_sem));
177 177
178 178 /*
179 179 * We need to prepare this buffer for the io:::start probe, including
180 180 * NULL'ing out the file, clearing the offset, and filling in the
181 181 * b_dip field.
182 182 */
183 183 bp->b_file = NULL;
184 184 bp->b_offset = -1;
185 185
186 186 if (dev != NODEV) {
187 187 (void) devopsp[getmajor(dev)]->devo_getinfo(NULL,
188 188 DDI_INFO_DEVT2DEVINFO, (void *)dev, (void **)&bp->b_dip);
189 189 } else {
190 190 bp->b_dip = NULL;
191 191 }
192 192
193 193 while (uio->uio_iovcnt > 0) {
194 194 iov = uio->uio_iov;
195 195
196 196 bp->b_error = 0;
197 197 bp->b_proc = procp;
198 198
199 199 while (iov->iov_len > 0) {
200 200 if (uio->uio_resid == 0)
201 201 break;
202 202 if (uio->uio_loffset < 0) {
203 203 error = EINVAL;
204 204 break;
205 205 }
206 206 #ifdef _ILP32
207 207 /*
208 208 * For 32-bit kernels, check against SPEC_MAXOFFSET_T
209 209 * which represents the maximum size that can be
210 210 * supported by the IO subsystem.
211 211 * XXX this code assumes a D_64BIT driver.
212 212 */
213 213 if (uio->uio_loffset > SPEC_MAXOFFSET_T) {
214 214 error = EINVAL;
215 215 break;
216 216 }
217 217 #endif /* _ILP32 */
218 218 bp->b_flags = B_BUSY | B_PHYS | rw;
219 219 bp->b_edev = dev;
220 220 bp->b_lblkno = btodt(uio->uio_loffset);
221 221
222 222 /*
223 223 * Don't count on b_addr remaining untouched by the
224 224 * code below (it may be reset because someone does
225 225 * a bp_mapin on the buffer) -- reset from the iov
226 226 * each time through, updating the iov's base address
227 227 * instead.
228 228 */
229 229 a = bp->b_un.b_addr = iov->iov_base;
230 230 bp->b_bcount = MIN(iov->iov_len, uio->uio_resid);
231 231 (*mincnt)(bp);
232 232 c = bp->b_bcount;
233 233
234 234 TRACE_1(TR_FAC_PHYSIO, TR_PHYSIO_LOCK_START,
235 235 "as_pagelock_start: bp %p", bp);
236 236
237 237 error = as_pagelock(asp, &pplist, a,
238 238 c, rw == B_READ? S_WRITE : S_READ);
239 239
240 240 TRACE_0(TR_FAC_PHYSIO, TR_PHYSIO_LOCK_END,
241 241 "as_pagelock_end:");
242 242
243 243 if (error != 0) {
244 244 bp->b_flags |= B_ERROR;
245 245 bp->b_error = error;
246 246 bp->b_flags &= ~(B_BUSY|B_WANTED|B_PHYS);
247 247 break;
248 248 }
249 249 bp->b_shadow = pplist;
250 250 if (pplist != NULL) {
251 251 bp->b_flags |= B_SHADOW;
252 252 }
253 253
254 254 DTRACE_IO1(start, struct buf *, bp);
255 255 bp->b_flags |= B_STARTED;
256 256
257 257 (void) (*strat)(bp);
258 258 error = biowait(bp);
259 259
260 260 /*
261 261 * unlock the pages
262 262 */
263 263 TRACE_1(TR_FAC_PHYSIO, TR_PHYSIO_UNLOCK_START,
264 264 "as_pageunlock_start: bp %p", bp);
265 265
266 266 as_pageunlock(asp, pplist, a, c,
267 267 rw == B_READ? S_WRITE : S_READ);
268 268
269 269 TRACE_0(TR_FAC_PHYSIO, TR_PHYSIO_UNLOCK_END,
270 270 "as_pageunlock_end:");
271 271
272 272 c -= bp->b_resid;
273 273 iov->iov_base += c;
274 274 iov->iov_len -= c;
275 275 uio->uio_resid -= c;
276 276 uio->uio_loffset += c;
277 277 /* bp->b_resid - temp kludge for tape drives */
278 278 if (bp->b_resid || error)
279 279 break;
280 280 }
281 281 bp->b_flags &= ~(B_BUSY|B_WANTED|B_PHYS|B_SHADOW);
282 282 /* bp->b_resid - temp kludge for tape drives */
283 283 if (bp->b_resid || error)
284 284 break;
285 285 uio->uio_iov++;
286 286 uio->uio_iovcnt--;
287 287 }
288 288
289 289 if (allocbuf) {
290 290 kmem_cache_free(physio_buf_cache, bp);
291 291 }
292 292
293 293 /* Kernel probe */
294 294 TNF_PROBE_1(physio_end, "io rawio", /* CSTYLED */,
295 295 tnf_device, device, dev);
296 296
297 297 TRACE_1(TR_FAC_PHYSIO, TR_PHYSIO_END, "physio_end: bp %p", bp);
298 298
299 299 return (error);
300 300 }
301 301
302 302 /*
303 303 * Returns 0 on success, or an error on failure.
304 304 *
305 305 * This function is no longer a part of the DDI/DKI.
306 306 * However, for compatibility, its interface should not
307 307 * be changed and it should not be removed from the kernel.
308 308 */
309 309 int
310 310 useracc(void *addr, size_t count, int access)
311 311 {
312 312 uint_t prot;
313 313
314 314 prot = PROT_USER | ((access == B_READ) ? PROT_READ : PROT_WRITE);
315 315 return (as_checkprot(ttoproc(curthread)->p_as, addr, count, prot));
316 316 }
317 317
318 318 #define MAX_MAPIN_PAGES 8
319 319
320 320 /*
321 321 * This function temporarily "borrows" user pages for kernel use. If
322 322 * "cow" is on, it also sets up copy-on-write protection (only feasible
323 323 * on MAP_PRIVATE segment) on the user mappings, to protect the borrowed
324 324 * pages from any changes by the user. The caller is responsible for
325 325 * unlocking and tearing down cow settings when it's done with the pages.
326 326 * For an example, see kcfree().
327 327 *
328 328 * Pages behind [uaddr..uaddr+*lenp] under address space "as" are locked
329 329 * (shared), and mapped into kernel address range [kaddr..kaddr+*lenp] if
330 330 * kaddr != -1. On entering this function, cached_ppp contains a list
331 331 * of pages that are mapped into [kaddr..kaddr+*lenp] already (from a
332 332 * previous call). Thus if same pages remain behind [uaddr..uaddr+*lenp],
333 333 * the kernel map won't need to be reloaded again.
334 334 *
335 335 * For cow == 1, if the pages are anonymous pages, it also bumps the anon
336 336 * reference count, and change the user-mapping to read-only. This
337 337 * scheme should work on all types of segment drivers. But to be safe,
338 338 * we check against segvn here.
339 339 *
340 340 * Since this function is used to emulate copyin() semantic, it checks
341 341 * to make sure the user-mappings allow "user-read".
342 342 *
343 343 * On exit "lenp" contains the number of bytes successfully locked and
344 344 * mapped in. For the unsuccessful ones, the caller can fall back to
345 345 * copyin().
346 346 *
347 347 * Error return:
348 348 * ENOTSUP - operation like this is not supported either on this segment
349 349 * type, or on this platform type.
350 350 */
351 351 int
352 352 cow_mapin(struct as *as, caddr_t uaddr, caddr_t kaddr, struct page **cached_ppp,
353 353 struct anon **app, size_t *lenp, int cow)
354 354 {
355 355 struct hat *hat;
356 356 struct seg *seg;
357 357 caddr_t base;
358 358 page_t *pp, *ppp[MAX_MAPIN_PAGES];
359 359 long i;
360 360 int flags;
361 361 size_t size, total = *lenp;
362 362 char first = 1;
363 363 faultcode_t res;
364 364
365 365 *lenp = 0;
366 366 if (cow) {
367 367 AS_LOCK_ENTER(as, &as->a_lock, RW_WRITER);
368 368 seg = as_findseg(as, uaddr, 0);
369 369 if ((seg == NULL) || ((base = seg->s_base) > uaddr) ||
370 370 (uaddr + total) > base + seg->s_size) {
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371 371 AS_LOCK_EXIT(as, &as->a_lock);
372 372 return (EINVAL);
373 373 }
374 374 /*
375 375 * The COW scheme should work for all segment types.
376 376 * But to be safe, we check against segvn.
377 377 */
378 378 if (seg->s_ops != &segvn_ops) {
379 379 AS_LOCK_EXIT(as, &as->a_lock);
380 380 return (ENOTSUP);
381 - } else if ((SEGOP_GETTYPE(seg, uaddr) & MAP_PRIVATE) == 0) {
381 + } else if ((segop_gettype(seg, uaddr) & MAP_PRIVATE) == 0) {
382 382 AS_LOCK_EXIT(as, &as->a_lock);
383 383 return (ENOTSUP);
384 384 }
385 385 }
386 386 hat = as->a_hat;
387 387 size = total;
388 388 tryagain:
389 389 /*
390 390 * If (cow), hat_softlock will also change the usr protection to RO.
391 391 * This is the first step toward setting up cow. Before we
392 392 * bump up an_refcnt, we can't allow any cow-fault on this
393 393 * address. Otherwise segvn_fault will change the protection back
394 394 * to RW upon seeing an_refcnt == 1.
395 395 * The solution is to hold the writer lock on "as".
396 396 */
397 397 res = hat_softlock(hat, uaddr, &size, &ppp[0], cow ? HAT_COW : 0);
398 398 size = total - size;
399 399 *lenp += size;
400 400 size = size >> PAGESHIFT;
401 401 i = 0;
402 402 while (i < size) {
403 403 pp = ppp[i];
404 404 if (cow) {
405 405 kmutex_t *ahm;
406 406 /*
407 407 * Another solution is to hold SE_EXCL on pp, and
408 408 * disable PROT_WRITE. This also works for MAP_SHARED
409 409 * segment. The disadvantage is that it locks the
410 410 * page from being used by anybody else.
411 411 */
412 412 ahm = AH_MUTEX(pp->p_vnode, pp->p_offset);
413 413 mutex_enter(ahm);
414 414 *app = swap_anon(pp->p_vnode, pp->p_offset);
415 415 /*
416 416 * Since we are holding the as lock, this avoids a
417 417 * potential race with anon_decref. (segvn_unmap and
418 418 * segvn_free needs the as writer lock to do anon_free.)
419 419 */
420 420 if (*app != NULL) {
421 421 #if 0
422 422 if ((*app)->an_refcnt == 0)
423 423 /*
424 424 * Consider the following senario (unlikey
425 425 * though):
426 426 * 1. an_refcnt == 2
427 427 * 2. we solftlock the page.
428 428 * 3. cow ocurrs on this addr. So a new ap,
429 429 * page and mapping is established on addr.
430 430 * 4. an_refcnt drops to 1 (segvn_faultpage
431 431 * -> anon_decref(oldap))
432 432 * 5. the last ref to ap also drops (from
433 433 * another as). It ends up blocked inside
434 434 * anon_decref trying to get page's excl lock.
435 435 * 6. Later kcfree unlocks the page, call
436 436 * anon_decref -> oops, ap is gone already.
437 437 *
438 438 * Holding as writer lock solves all problems.
439 439 */
440 440 *app = NULL;
441 441 else
442 442 #endif
443 443 (*app)->an_refcnt++;
444 444 }
445 445 mutex_exit(ahm);
446 446 } else {
447 447 *app = NULL;
448 448 }
449 449 if (kaddr != (caddr_t)-1) {
450 450 if (pp != *cached_ppp) {
451 451 if (*cached_ppp == NULL)
452 452 flags = HAT_LOAD_LOCK | HAT_NOSYNC |
453 453 HAT_LOAD_NOCONSIST;
454 454 else
455 455 flags = HAT_LOAD_REMAP |
456 456 HAT_LOAD_NOCONSIST;
457 457 /*
458 458 * In order to cache the kernel mapping after
459 459 * the user page is unlocked, we call
460 460 * hat_devload instead of hat_memload so
461 461 * that the kernel mapping we set up here is
462 462 * "invisible" to the rest of the world. This
463 463 * is not very pretty. But as long as the
464 464 * caller bears the responsibility of keeping
465 465 * cache consistency, we should be ok -
466 466 * HAT_NOCONSIST will get us a uncached
467 467 * mapping on VAC. hat_softlock will flush
468 468 * a VAC_WRITEBACK cache. Therefore the kaddr
469 469 * doesn't have to be of the same vcolor as
470 470 * uaddr.
471 471 * The alternative is - change hat_devload
472 472 * to get a cached mapping. Allocate a kaddr
473 473 * with the same vcolor as uaddr. Then
474 474 * hat_softlock won't need to flush the VAC.
475 475 */
476 476 hat_devload(kas.a_hat, kaddr, PAGESIZE,
477 477 page_pptonum(pp), PROT_READ, flags);
478 478 *cached_ppp = pp;
479 479 }
480 480 kaddr += PAGESIZE;
481 481 }
482 482 cached_ppp++;
483 483 app++;
484 484 ++i;
485 485 }
486 486 if (cow) {
487 487 AS_LOCK_EXIT(as, &as->a_lock);
488 488 }
489 489 if (first && res == FC_NOMAP) {
490 490 /*
491 491 * If the address is not mapped yet, we call as_fault to
492 492 * fault the pages in. We could've fallen back to copy and
493 493 * let it fault in the pages. But for a mapped file, we
494 494 * normally reference each page only once. For zero-copy to
495 495 * be of any use, we'd better fall in the page now and try
496 496 * again.
497 497 */
498 498 first = 0;
499 499 size = size << PAGESHIFT;
500 500 uaddr += size;
501 501 total -= size;
502 502 size = total;
503 503 res = as_fault(as->a_hat, as, uaddr, size, F_INVAL, S_READ);
504 504 if (cow)
505 505 AS_LOCK_ENTER(as, &as->a_lock, RW_WRITER);
506 506 goto tryagain;
507 507 }
508 508 switch (res) {
509 509 case FC_NOSUPPORT:
510 510 return (ENOTSUP);
511 511 case FC_PROT: /* Pretend we don't know about it. This will be */
512 512 /* caught by the caller when uiomove fails. */
513 513 case FC_NOMAP:
514 514 case FC_OBJERR:
515 515 default:
516 516 return (0);
517 517 }
518 518 }
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