FreeBSD/Linux Kernel Cross Reference
sys/kern/kern_subr.c
1 /*
2 * Copyright (c) 1982, 1986, 1991, 1993
3 * The Regents of the University of California. All rights reserved.
4 * (c) UNIX System Laboratories, Inc.
5 * All or some portions of this file are derived from material licensed
6 * to the University of California by American Telephone and Telegraph
7 * Co. or Unix System Laboratories, Inc. and are reproduced herein with
8 * the permission of UNIX System Laboratories, Inc.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 * 4. Neither the name of the University nor the names of its contributors
19 * may be used to endorse or promote products derived from this software
20 * without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * SUCH DAMAGE.
33 *
34 * @(#)kern_subr.c 8.3 (Berkeley) 1/21/94
35 */
36
37 #include <sys/cdefs.h>
38 __FBSDID("$FreeBSD: releng/5.3/sys/kern/kern_subr.c 136588 2004-10-16 08:43:07Z cvs2svn $");
39
40 #include "opt_zero.h"
41
42 #include <sys/param.h>
43 #include <sys/systm.h>
44 #include <sys/kernel.h>
45 #include <sys/ktr.h>
46 #include <sys/limits.h>
47 #include <sys/lock.h>
48 #include <sys/mutex.h>
49 #include <sys/proc.h>
50 #include <sys/malloc.h>
51 #include <sys/resourcevar.h>
52 #include <sys/sched.h>
53 #include <sys/sysctl.h>
54 #include <sys/vnode.h>
55
56 #include <vm/vm.h>
57 #include <vm/vm_page.h>
58 #include <vm/vm_map.h>
59 #ifdef ZERO_COPY_SOCKETS
60 #include <vm/vm_param.h>
61 #include <vm/vm_object.h>
62 #endif
63
64 SYSCTL_INT(_kern, KERN_IOV_MAX, iov_max, CTLFLAG_RD, NULL, UIO_MAXIOV,
65 "Maximum number of elements in an I/O vector; sysconf(_SC_IOV_MAX)");
66
67 #ifdef ZERO_COPY_SOCKETS
68 /* Declared in uipc_socket.c */
69 extern int so_zero_copy_receive;
70
71 static int
72 vm_pgmoveco(vm_map_t mapa, vm_object_t srcobj, vm_offset_t kaddr,
73 vm_offset_t uaddr)
74 {
75 vm_map_t map = mapa;
76 vm_page_t kern_pg, user_pg;
77 vm_object_t uobject;
78 vm_map_entry_t entry;
79 vm_pindex_t upindex, kpindex;
80 vm_prot_t prot;
81 boolean_t wired;
82
83 /*
84 * First lookup the kernel page.
85 */
86 kern_pg = PHYS_TO_VM_PAGE(vtophys(kaddr));
87 /*
88 * XXX The vm object containing kern_pg needs locking.
89 */
90 if ((vm_map_lookup(&map, uaddr,
91 VM_PROT_WRITE, &entry, &uobject,
92 &upindex, &prot, &wired)) != KERN_SUCCESS) {
93 return(EFAULT);
94 }
95 VM_OBJECT_LOCK(uobject);
96 if ((user_pg = vm_page_lookup(uobject, upindex)) != NULL) {
97 do
98 vm_page_lock_queues();
99 while (vm_page_sleep_if_busy(user_pg, 1, "vm_pgmoveco"));
100 vm_page_busy(user_pg);
101 pmap_remove_all(user_pg);
102 vm_page_free(user_pg);
103 } else
104 vm_page_lock_queues();
105 if (kern_pg->busy || ((kern_pg->queue - kern_pg->pc) == PQ_FREE) ||
106 (kern_pg->hold_count != 0)|| (kern_pg->flags & PG_BUSY)) {
107 printf("vm_pgmoveco: pindex(%lu), busy(%d), PG_BUSY(%d), "
108 "hold(%d) paddr(0x%lx)\n", (u_long)kern_pg->pindex,
109 kern_pg->busy, (kern_pg->flags & PG_BUSY) ? 1 : 0,
110 kern_pg->hold_count, (u_long)kern_pg->phys_addr);
111 if ((kern_pg->queue - kern_pg->pc) == PQ_FREE)
112 panic("vm_pgmoveco: renaming free page");
113 else
114 panic("vm_pgmoveco: renaming busy page");
115 }
116 kpindex = kern_pg->pindex;
117 vm_page_busy(kern_pg);
118 vm_page_rename(kern_pg, uobject, upindex);
119 vm_page_flag_clear(kern_pg, PG_BUSY);
120 kern_pg->valid = VM_PAGE_BITS_ALL;
121 vm_page_unlock_queues();
122 VM_OBJECT_UNLOCK(uobject);
123 vm_map_lookup_done(map, entry);
124 return(KERN_SUCCESS);
125 }
126 #endif /* ZERO_COPY_SOCKETS */
127
128 int
129 uiomove(void *cp, int n, struct uio *uio)
130 {
131 struct thread *td = curthread;
132 struct iovec *iov;
133 u_int cnt;
134 int error = 0;
135 int save = 0;
136
137 KASSERT(uio->uio_rw == UIO_READ || uio->uio_rw == UIO_WRITE,
138 ("uiomove: mode"));
139 KASSERT(uio->uio_segflg != UIO_USERSPACE || uio->uio_td == curthread,
140 ("uiomove proc"));
141
142 save = td->td_pflags & TDP_DEADLKTREAT;
143 td->td_pflags |= TDP_DEADLKTREAT;
144
145 while (n > 0 && uio->uio_resid) {
146 iov = uio->uio_iov;
147 cnt = iov->iov_len;
148 if (cnt == 0) {
149 uio->uio_iov++;
150 uio->uio_iovcnt--;
151 continue;
152 }
153 if (cnt > n)
154 cnt = n;
155
156 switch (uio->uio_segflg) {
157
158 case UIO_USERSPACE:
159 if (ticks - PCPU_GET(switchticks) >= hogticks)
160 uio_yield();
161 if (uio->uio_rw == UIO_READ)
162 error = copyout(cp, iov->iov_base, cnt);
163 else
164 error = copyin(iov->iov_base, cp, cnt);
165 if (error)
166 goto out;
167 break;
168
169 case UIO_SYSSPACE:
170 if (uio->uio_rw == UIO_READ)
171 bcopy(cp, iov->iov_base, cnt);
172 else
173 bcopy(iov->iov_base, cp, cnt);
174 break;
175 case UIO_NOCOPY:
176 break;
177 }
178 iov->iov_base = (char *)iov->iov_base + cnt;
179 iov->iov_len -= cnt;
180 uio->uio_resid -= cnt;
181 uio->uio_offset += cnt;
182 cp = (char *)cp + cnt;
183 n -= cnt;
184 }
185 out:
186 if (save == 0)
187 td->td_pflags &= ~TDP_DEADLKTREAT;
188 return (error);
189 }
190
191 /*
192 * Wrapper for uiomove() that validates the arguments against a known-good
193 * kernel buffer. Currently, uiomove accepts a signed (n) argument, which
194 * is almost definitely a bad thing, so we catch that here as well. We
195 * return a runtime failure, but it might be desirable to generate a runtime
196 * assertion failure instead.
197 */
198 int
199 uiomove_frombuf(void *buf, int buflen, struct uio *uio)
200 {
201 unsigned int offset, n;
202
203 if (uio->uio_offset < 0 || uio->uio_resid < 0 ||
204 (offset = uio->uio_offset) != uio->uio_offset)
205 return (EINVAL);
206 if (buflen <= 0 || offset >= buflen)
207 return (0);
208 if ((n = buflen - offset) > INT_MAX)
209 return (EINVAL);
210 return (uiomove((char *)buf + offset, n, uio));
211 }
212
213 #ifdef ZERO_COPY_SOCKETS
214 /*
215 * Experimental support for zero-copy I/O
216 */
217 static int
218 userspaceco(void *cp, u_int cnt, struct uio *uio, struct vm_object *obj,
219 int disposable)
220 {
221 struct iovec *iov;
222 int error;
223
224 iov = uio->uio_iov;
225 if (uio->uio_rw == UIO_READ) {
226 if ((so_zero_copy_receive != 0)
227 && (obj != NULL)
228 && ((cnt & PAGE_MASK) == 0)
229 && ((((intptr_t) iov->iov_base) & PAGE_MASK) == 0)
230 && ((uio->uio_offset & PAGE_MASK) == 0)
231 && ((((intptr_t) cp) & PAGE_MASK) == 0)
232 && (obj->type == OBJT_DEFAULT)
233 && (disposable != 0)) {
234 /* SOCKET: use page-trading */
235 /*
236 * We only want to call vm_pgmoveco() on
237 * disposeable pages, since it gives the
238 * kernel page to the userland process.
239 */
240 error = vm_pgmoveco(&curproc->p_vmspace->vm_map,
241 obj, (vm_offset_t)cp,
242 (vm_offset_t)iov->iov_base);
243
244 /*
245 * If we get an error back, attempt
246 * to use copyout() instead. The
247 * disposable page should be freed
248 * automatically if we weren't able to move
249 * it into userland.
250 */
251 if (error != 0)
252 error = copyout(cp, iov->iov_base, cnt);
253 } else {
254 error = copyout(cp, iov->iov_base, cnt);
255 }
256 } else {
257 error = copyin(iov->iov_base, cp, cnt);
258 }
259 return (error);
260 }
261
262 int
263 uiomoveco(void *cp, int n, struct uio *uio, struct vm_object *obj,
264 int disposable)
265 {
266 struct iovec *iov;
267 u_int cnt;
268 int error;
269
270 KASSERT(uio->uio_rw == UIO_READ || uio->uio_rw == UIO_WRITE,
271 ("uiomoveco: mode"));
272 KASSERT(uio->uio_segflg != UIO_USERSPACE || uio->uio_td == curthread,
273 ("uiomoveco proc"));
274
275 while (n > 0 && uio->uio_resid) {
276 iov = uio->uio_iov;
277 cnt = iov->iov_len;
278 if (cnt == 0) {
279 uio->uio_iov++;
280 uio->uio_iovcnt--;
281 continue;
282 }
283 if (cnt > n)
284 cnt = n;
285
286 switch (uio->uio_segflg) {
287
288 case UIO_USERSPACE:
289 if (ticks - PCPU_GET(switchticks) >= hogticks)
290 uio_yield();
291
292 error = userspaceco(cp, cnt, uio, obj, disposable);
293
294 if (error)
295 return (error);
296 break;
297
298 case UIO_SYSSPACE:
299 if (uio->uio_rw == UIO_READ)
300 bcopy(cp, iov->iov_base, cnt);
301 else
302 bcopy(iov->iov_base, cp, cnt);
303 break;
304 case UIO_NOCOPY:
305 break;
306 }
307 iov->iov_base = (char *)iov->iov_base + cnt;
308 iov->iov_len -= cnt;
309 uio->uio_resid -= cnt;
310 uio->uio_offset += cnt;
311 cp = (char *)cp + cnt;
312 n -= cnt;
313 }
314 return (0);
315 }
316 #endif /* ZERO_COPY_SOCKETS */
317
318 /*
319 * Give next character to user as result of read.
320 */
321 int
322 ureadc(int c, struct uio *uio)
323 {
324 struct iovec *iov;
325 char *iov_base;
326
327 again:
328 if (uio->uio_iovcnt == 0 || uio->uio_resid == 0)
329 panic("ureadc");
330 iov = uio->uio_iov;
331 if (iov->iov_len == 0) {
332 uio->uio_iovcnt--;
333 uio->uio_iov++;
334 goto again;
335 }
336 switch (uio->uio_segflg) {
337
338 case UIO_USERSPACE:
339 if (subyte(iov->iov_base, c) < 0)
340 return (EFAULT);
341 break;
342
343 case UIO_SYSSPACE:
344 iov_base = iov->iov_base;
345 *iov_base = c;
346 iov->iov_base = iov_base;
347 break;
348
349 case UIO_NOCOPY:
350 break;
351 }
352 iov->iov_base = (char *)iov->iov_base + 1;
353 iov->iov_len--;
354 uio->uio_resid--;
355 uio->uio_offset++;
356 return (0);
357 }
358
359 /*
360 * General routine to allocate a hash table.
361 */
362 void *
363 hashinit(int elements, struct malloc_type *type, u_long *hashmask)
364 {
365 long hashsize;
366 LIST_HEAD(generic, generic) *hashtbl;
367 int i;
368
369 if (elements <= 0)
370 panic("hashinit: bad elements");
371 for (hashsize = 1; hashsize <= elements; hashsize <<= 1)
372 continue;
373 hashsize >>= 1;
374 hashtbl = malloc((u_long)hashsize * sizeof(*hashtbl), type, M_WAITOK);
375 for (i = 0; i < hashsize; i++)
376 LIST_INIT(&hashtbl[i]);
377 *hashmask = hashsize - 1;
378 return (hashtbl);
379 }
380
381 void
382 hashdestroy(void *vhashtbl, struct malloc_type *type, u_long hashmask)
383 {
384 LIST_HEAD(generic, generic) *hashtbl, *hp;
385
386 hashtbl = vhashtbl;
387 for (hp = hashtbl; hp <= &hashtbl[hashmask]; hp++)
388 if (!LIST_EMPTY(hp))
389 panic("hashdestroy: hash not empty");
390 free(hashtbl, type);
391 }
392
393 static int primes[] = { 1, 13, 31, 61, 127, 251, 509, 761, 1021, 1531, 2039,
394 2557, 3067, 3583, 4093, 4603, 5119, 5623, 6143, 6653,
395 7159, 7673, 8191, 12281, 16381, 24571, 32749 };
396 #define NPRIMES (sizeof(primes) / sizeof(primes[0]))
397
398 /*
399 * General routine to allocate a prime number sized hash table.
400 */
401 void *
402 phashinit(int elements, struct malloc_type *type, u_long *nentries)
403 {
404 long hashsize;
405 LIST_HEAD(generic, generic) *hashtbl;
406 int i;
407
408 if (elements <= 0)
409 panic("phashinit: bad elements");
410 for (i = 1, hashsize = primes[1]; hashsize <= elements;) {
411 i++;
412 if (i == NPRIMES)
413 break;
414 hashsize = primes[i];
415 }
416 hashsize = primes[i - 1];
417 hashtbl = malloc((u_long)hashsize * sizeof(*hashtbl), type, M_WAITOK);
418 for (i = 0; i < hashsize; i++)
419 LIST_INIT(&hashtbl[i]);
420 *nentries = hashsize;
421 return (hashtbl);
422 }
423
424 void
425 uio_yield(void)
426 {
427 struct thread *td;
428
429 td = curthread;
430 mtx_lock_spin(&sched_lock);
431 DROP_GIANT();
432 sched_prio(td, td->td_ksegrp->kg_user_pri); /* XXXKSE */
433 mi_switch(SW_INVOL, NULL);
434 mtx_unlock_spin(&sched_lock);
435 PICKUP_GIANT();
436 }
437
438 int
439 copyinfrom(const void * __restrict src, void * __restrict dst, size_t len,
440 int seg)
441 {
442 int error = 0;
443
444 switch (seg) {
445 case UIO_USERSPACE:
446 error = copyin(src, dst, len);
447 break;
448 case UIO_SYSSPACE:
449 bcopy(src, dst, len);
450 break;
451 default:
452 panic("copyinfrom: bad seg %d\n", seg);
453 }
454 return (error);
455 }
456
457 int
458 copyinstrfrom(const void * __restrict src, void * __restrict dst, size_t len,
459 size_t * __restrict copied, int seg)
460 {
461 int error = 0;
462
463 switch (seg) {
464 case UIO_USERSPACE:
465 error = copyinstr(src, dst, len, copied);
466 break;
467 case UIO_SYSSPACE:
468 error = copystr(src, dst, len, copied);
469 break;
470 default:
471 panic("copyinstrfrom: bad seg %d\n", seg);
472 }
473 return (error);
474 }
475
476 int
477 copyiniov(struct iovec *iovp, u_int iovcnt, struct iovec **iov, int error)
478 {
479 u_int iovlen;
480
481 *iov = NULL;
482 if (iovcnt > UIO_MAXIOV)
483 return (error);
484 iovlen = iovcnt * sizeof (struct iovec);
485 *iov = malloc(iovlen, M_IOV, M_WAITOK);
486 error = copyin(iovp, *iov, iovlen);
487 if (error) {
488 free(*iov, M_IOV);
489 *iov = NULL;
490 }
491 return (error);
492 }
493
494 int
495 copyinuio(struct iovec *iovp, u_int iovcnt, struct uio **uiop)
496 {
497 struct iovec *iov;
498 struct uio *uio;
499 u_int iovlen;
500 int error, i;
501
502 *uiop = NULL;
503 if (iovcnt > UIO_MAXIOV)
504 return (EINVAL);
505 iovlen = iovcnt * sizeof (struct iovec);
506 uio = malloc(iovlen + sizeof *uio, M_IOV, M_WAITOK);
507 iov = (struct iovec *)(uio + 1);
508 error = copyin(iovp, iov, iovlen);
509 if (error) {
510 free(uio, M_IOV);
511 return (error);
512 }
513 uio->uio_iov = iov;
514 uio->uio_iovcnt = iovcnt;
515 uio->uio_segflg = UIO_USERSPACE;
516 uio->uio_offset = -1;
517 uio->uio_resid = 0;
518 for (i = 0; i < iovcnt; i++) {
519 if (iov->iov_len > INT_MAX - uio->uio_resid) {
520 free(uio, M_IOV);
521 return (EINVAL);
522 }
523 uio->uio_resid += iov->iov_len;
524 iov++;
525 }
526 *uiop = uio;
527 return (0);
528 }
529
530 struct uio *
531 cloneuio(struct uio *uiop)
532 {
533 struct uio *uio;
534 int iovlen;
535
536 iovlen = uiop->uio_iovcnt * sizeof (struct iovec);
537 uio = malloc(iovlen + sizeof *uio, M_IOV, M_WAITOK);
538 *uio = *uiop;
539 uio->uio_iov = (struct iovec *)(uio + 1);
540 bcopy(uiop->uio_iov, uio->uio_iov, iovlen);
541 return (uio);
542 }
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