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: src/sys/kern/kern_subr.c,v 1.88.2.2 2005/01/31 23:26:16 imp Exp $");
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 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL,
142 "Calling uiomove()");
143
144 save = td->td_pflags & TDP_DEADLKTREAT;
145 td->td_pflags |= TDP_DEADLKTREAT;
146
147 while (n > 0 && uio->uio_resid) {
148 iov = uio->uio_iov;
149 cnt = iov->iov_len;
150 if (cnt == 0) {
151 uio->uio_iov++;
152 uio->uio_iovcnt--;
153 continue;
154 }
155 if (cnt > n)
156 cnt = n;
157
158 switch (uio->uio_segflg) {
159
160 case UIO_USERSPACE:
161 if (ticks - PCPU_GET(switchticks) >= hogticks)
162 uio_yield();
163 if (uio->uio_rw == UIO_READ)
164 error = copyout(cp, iov->iov_base, cnt);
165 else
166 error = copyin(iov->iov_base, cp, cnt);
167 if (error)
168 goto out;
169 break;
170
171 case UIO_SYSSPACE:
172 if (uio->uio_rw == UIO_READ)
173 bcopy(cp, iov->iov_base, cnt);
174 else
175 bcopy(iov->iov_base, cp, cnt);
176 break;
177 case UIO_NOCOPY:
178 break;
179 }
180 iov->iov_base = (char *)iov->iov_base + cnt;
181 iov->iov_len -= cnt;
182 uio->uio_resid -= cnt;
183 uio->uio_offset += cnt;
184 cp = (char *)cp + cnt;
185 n -= cnt;
186 }
187 out:
188 if (save == 0)
189 td->td_pflags &= ~TDP_DEADLKTREAT;
190 return (error);
191 }
192
193 /*
194 * Wrapper for uiomove() that validates the arguments against a known-good
195 * kernel buffer. Currently, uiomove accepts a signed (n) argument, which
196 * is almost definitely a bad thing, so we catch that here as well. We
197 * return a runtime failure, but it might be desirable to generate a runtime
198 * assertion failure instead.
199 */
200 int
201 uiomove_frombuf(void *buf, int buflen, struct uio *uio)
202 {
203 unsigned int offset, n;
204
205 if (uio->uio_offset < 0 || uio->uio_resid < 0 ||
206 (offset = uio->uio_offset) != uio->uio_offset)
207 return (EINVAL);
208 if (buflen <= 0 || offset >= buflen)
209 return (0);
210 if ((n = buflen - offset) > INT_MAX)
211 return (EINVAL);
212 return (uiomove((char *)buf + offset, n, uio));
213 }
214
215 #ifdef ZERO_COPY_SOCKETS
216 /*
217 * Experimental support for zero-copy I/O
218 */
219 static int
220 userspaceco(void *cp, u_int cnt, struct uio *uio, struct vm_object *obj,
221 int disposable)
222 {
223 struct iovec *iov;
224 int error;
225
226 iov = uio->uio_iov;
227 if (uio->uio_rw == UIO_READ) {
228 if ((so_zero_copy_receive != 0)
229 && (obj != NULL)
230 && ((cnt & PAGE_MASK) == 0)
231 && ((((intptr_t) iov->iov_base) & PAGE_MASK) == 0)
232 && ((uio->uio_offset & PAGE_MASK) == 0)
233 && ((((intptr_t) cp) & PAGE_MASK) == 0)
234 && (obj->type == OBJT_DEFAULT)
235 && (disposable != 0)) {
236 /* SOCKET: use page-trading */
237 /*
238 * We only want to call vm_pgmoveco() on
239 * disposeable pages, since it gives the
240 * kernel page to the userland process.
241 */
242 error = vm_pgmoveco(&curproc->p_vmspace->vm_map,
243 obj, (vm_offset_t)cp,
244 (vm_offset_t)iov->iov_base);
245
246 /*
247 * If we get an error back, attempt
248 * to use copyout() instead. The
249 * disposable page should be freed
250 * automatically if we weren't able to move
251 * it into userland.
252 */
253 if (error != 0)
254 error = copyout(cp, iov->iov_base, cnt);
255 } else {
256 error = copyout(cp, iov->iov_base, cnt);
257 }
258 } else {
259 error = copyin(iov->iov_base, cp, cnt);
260 }
261 return (error);
262 }
263
264 int
265 uiomoveco(void *cp, int n, struct uio *uio, struct vm_object *obj,
266 int disposable)
267 {
268 struct iovec *iov;
269 u_int cnt;
270 int error;
271
272 KASSERT(uio->uio_rw == UIO_READ || uio->uio_rw == UIO_WRITE,
273 ("uiomoveco: mode"));
274 KASSERT(uio->uio_segflg != UIO_USERSPACE || uio->uio_td == curthread,
275 ("uiomoveco proc"));
276
277 while (n > 0 && uio->uio_resid) {
278 iov = uio->uio_iov;
279 cnt = iov->iov_len;
280 if (cnt == 0) {
281 uio->uio_iov++;
282 uio->uio_iovcnt--;
283 continue;
284 }
285 if (cnt > n)
286 cnt = n;
287
288 switch (uio->uio_segflg) {
289
290 case UIO_USERSPACE:
291 if (ticks - PCPU_GET(switchticks) >= hogticks)
292 uio_yield();
293
294 error = userspaceco(cp, cnt, uio, obj, disposable);
295
296 if (error)
297 return (error);
298 break;
299
300 case UIO_SYSSPACE:
301 if (uio->uio_rw == UIO_READ)
302 bcopy(cp, iov->iov_base, cnt);
303 else
304 bcopy(iov->iov_base, cp, cnt);
305 break;
306 case UIO_NOCOPY:
307 break;
308 }
309 iov->iov_base = (char *)iov->iov_base + cnt;
310 iov->iov_len -= cnt;
311 uio->uio_resid -= cnt;
312 uio->uio_offset += cnt;
313 cp = (char *)cp + cnt;
314 n -= cnt;
315 }
316 return (0);
317 }
318 #endif /* ZERO_COPY_SOCKETS */
319
320 /*
321 * Give next character to user as result of read.
322 */
323 int
324 ureadc(int c, struct uio *uio)
325 {
326 struct iovec *iov;
327 char *iov_base;
328
329 again:
330 if (uio->uio_iovcnt == 0 || uio->uio_resid == 0)
331 panic("ureadc");
332 iov = uio->uio_iov;
333 if (iov->iov_len == 0) {
334 uio->uio_iovcnt--;
335 uio->uio_iov++;
336 goto again;
337 }
338 switch (uio->uio_segflg) {
339
340 case UIO_USERSPACE:
341 if (subyte(iov->iov_base, c) < 0)
342 return (EFAULT);
343 break;
344
345 case UIO_SYSSPACE:
346 iov_base = iov->iov_base;
347 *iov_base = c;
348 iov->iov_base = iov_base;
349 break;
350
351 case UIO_NOCOPY:
352 break;
353 }
354 iov->iov_base = (char *)iov->iov_base + 1;
355 iov->iov_len--;
356 uio->uio_resid--;
357 uio->uio_offset++;
358 return (0);
359 }
360
361 /*
362 * General routine to allocate a hash table.
363 */
364 void *
365 hashinit(int elements, struct malloc_type *type, u_long *hashmask)
366 {
367 long hashsize;
368 LIST_HEAD(generic, generic) *hashtbl;
369 int i;
370
371 if (elements <= 0)
372 panic("hashinit: bad elements");
373 for (hashsize = 1; hashsize <= elements; hashsize <<= 1)
374 continue;
375 hashsize >>= 1;
376 hashtbl = malloc((u_long)hashsize * sizeof(*hashtbl), type, M_WAITOK);
377 for (i = 0; i < hashsize; i++)
378 LIST_INIT(&hashtbl[i]);
379 *hashmask = hashsize - 1;
380 return (hashtbl);
381 }
382
383 void
384 hashdestroy(void *vhashtbl, struct malloc_type *type, u_long hashmask)
385 {
386 LIST_HEAD(generic, generic) *hashtbl, *hp;
387
388 hashtbl = vhashtbl;
389 for (hp = hashtbl; hp <= &hashtbl[hashmask]; hp++)
390 if (!LIST_EMPTY(hp))
391 panic("hashdestroy: hash not empty");
392 free(hashtbl, type);
393 }
394
395 static int primes[] = { 1, 13, 31, 61, 127, 251, 509, 761, 1021, 1531, 2039,
396 2557, 3067, 3583, 4093, 4603, 5119, 5623, 6143, 6653,
397 7159, 7673, 8191, 12281, 16381, 24571, 32749 };
398 #define NPRIMES (sizeof(primes) / sizeof(primes[0]))
399
400 /*
401 * General routine to allocate a prime number sized hash table.
402 */
403 void *
404 phashinit(int elements, struct malloc_type *type, u_long *nentries)
405 {
406 long hashsize;
407 LIST_HEAD(generic, generic) *hashtbl;
408 int i;
409
410 if (elements <= 0)
411 panic("phashinit: bad elements");
412 for (i = 1, hashsize = primes[1]; hashsize <= elements;) {
413 i++;
414 if (i == NPRIMES)
415 break;
416 hashsize = primes[i];
417 }
418 hashsize = primes[i - 1];
419 hashtbl = malloc((u_long)hashsize * sizeof(*hashtbl), type, M_WAITOK);
420 for (i = 0; i < hashsize; i++)
421 LIST_INIT(&hashtbl[i]);
422 *nentries = hashsize;
423 return (hashtbl);
424 }
425
426 void
427 uio_yield(void)
428 {
429 struct thread *td;
430
431 td = curthread;
432 mtx_lock_spin(&sched_lock);
433 DROP_GIANT();
434 sched_prio(td, td->td_ksegrp->kg_user_pri); /* XXXKSE */
435 mi_switch(SW_INVOL, NULL);
436 mtx_unlock_spin(&sched_lock);
437 PICKUP_GIANT();
438 }
439
440 int
441 copyinfrom(const void * __restrict src, void * __restrict dst, size_t len,
442 int seg)
443 {
444 int error = 0;
445
446 switch (seg) {
447 case UIO_USERSPACE:
448 error = copyin(src, dst, len);
449 break;
450 case UIO_SYSSPACE:
451 bcopy(src, dst, len);
452 break;
453 default:
454 panic("copyinfrom: bad seg %d\n", seg);
455 }
456 return (error);
457 }
458
459 int
460 copyinstrfrom(const void * __restrict src, void * __restrict dst, size_t len,
461 size_t * __restrict copied, int seg)
462 {
463 int error = 0;
464
465 switch (seg) {
466 case UIO_USERSPACE:
467 error = copyinstr(src, dst, len, copied);
468 break;
469 case UIO_SYSSPACE:
470 error = copystr(src, dst, len, copied);
471 break;
472 default:
473 panic("copyinstrfrom: bad seg %d\n", seg);
474 }
475 return (error);
476 }
477
478 int
479 copyiniov(struct iovec *iovp, u_int iovcnt, struct iovec **iov, int error)
480 {
481 u_int iovlen;
482
483 *iov = NULL;
484 if (iovcnt > UIO_MAXIOV)
485 return (error);
486 iovlen = iovcnt * sizeof (struct iovec);
487 *iov = malloc(iovlen, M_IOV, M_WAITOK);
488 error = copyin(iovp, *iov, iovlen);
489 if (error) {
490 free(*iov, M_IOV);
491 *iov = NULL;
492 }
493 return (error);
494 }
495
496 int
497 copyinuio(struct iovec *iovp, u_int iovcnt, struct uio **uiop)
498 {
499 struct iovec *iov;
500 struct uio *uio;
501 u_int iovlen;
502 int error, i;
503
504 *uiop = NULL;
505 if (iovcnt > UIO_MAXIOV)
506 return (EINVAL);
507 iovlen = iovcnt * sizeof (struct iovec);
508 uio = malloc(iovlen + sizeof *uio, M_IOV, M_WAITOK);
509 iov = (struct iovec *)(uio + 1);
510 error = copyin(iovp, iov, iovlen);
511 if (error) {
512 free(uio, M_IOV);
513 return (error);
514 }
515 uio->uio_iov = iov;
516 uio->uio_iovcnt = iovcnt;
517 uio->uio_segflg = UIO_USERSPACE;
518 uio->uio_offset = -1;
519 uio->uio_resid = 0;
520 for (i = 0; i < iovcnt; i++) {
521 if (iov->iov_len > INT_MAX - uio->uio_resid) {
522 free(uio, M_IOV);
523 return (EINVAL);
524 }
525 uio->uio_resid += iov->iov_len;
526 iov++;
527 }
528 *uiop = uio;
529 return (0);
530 }
531
532 struct uio *
533 cloneuio(struct uio *uiop)
534 {
535 struct uio *uio;
536 int iovlen;
537
538 iovlen = uiop->uio_iovcnt * sizeof (struct iovec);
539 uio = malloc(iovlen + sizeof *uio, M_IOV, M_WAITOK);
540 *uio = *uiop;
541 uio->uio_iov = (struct iovec *)(uio + 1);
542 bcopy(uiop->uio_iov, uio->uio_iov, iovlen);
543 return (uio);
544 }
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