subr_hash.c revision 163709 
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: head/sys/kern/kern_subr.c 163709 2006-10-26 21:42:22Z jb $");
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
64SYSCTL_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 */
69extern int so_zero_copy_receive;
70
71/*
72 * Identify the physical page mapped at the given kernel virtual
73 * address.  Insert this physical page into the given address space at
74 * the given virtual address, replacing the physical page, if any,
75 * that already exists there.
76 */
77static int
78vm_pgmoveco(vm_map_t mapa, vm_offset_t kaddr, vm_offset_t uaddr)
79{
80	vm_map_t map = mapa;
81	vm_page_t kern_pg, user_pg;
82	vm_object_t uobject;
83	vm_map_entry_t entry;
84	vm_pindex_t upindex;
85	vm_prot_t prot;
86	boolean_t wired;
87
88	KASSERT((uaddr & PAGE_MASK) == 0,
89	    ("vm_pgmoveco: uaddr is not page aligned"));
90
91	/*
92	 * Herein the physical page is validated and dirtied.  It is
93	 * unwired in sf_buf_mext().
94	 */
95	kern_pg = PHYS_TO_VM_PAGE(vtophys(kaddr));
96	kern_pg->valid = VM_PAGE_BITS_ALL;
97	KASSERT(kern_pg->queue == PQ_NONE && kern_pg->wire_count == 1,
98	    ("vm_pgmoveco: kern_pg is not correctly wired"));
99
100	if ((vm_map_lookup(&map, uaddr,
101			   VM_PROT_WRITE, &entry, &uobject,
102			   &upindex, &prot, &wired)) != KERN_SUCCESS) {
103		return(EFAULT);
104	}
105	VM_OBJECT_LOCK(uobject);
106retry:
107	if ((user_pg = vm_page_lookup(uobject, upindex)) != NULL) {
108		if (vm_page_sleep_if_busy(user_pg, TRUE, "vm_pgmoveco"))
109			goto retry;
110		vm_page_lock_queues();
111		pmap_remove_all(user_pg);
112		vm_page_free(user_pg);
113	} else {
114		/*
115		 * Even if a physical page does not exist in the
116		 * object chain's first object, a physical page from a
117		 * backing object may be mapped read only.
118		 */
119		if (uobject->backing_object != NULL)
120			pmap_remove(map->pmap, uaddr, uaddr + PAGE_SIZE);
121		vm_page_lock_queues();
122	}
123	vm_page_insert(kern_pg, uobject, upindex);
124	vm_page_dirty(kern_pg);
125	vm_page_unlock_queues();
126	VM_OBJECT_UNLOCK(uobject);
127	vm_map_lookup_done(map, entry);
128	return(KERN_SUCCESS);
129}
130#endif /* ZERO_COPY_SOCKETS */
131
132int
133uiomove(void *cp, int n, struct uio *uio)
134{
135	struct thread *td = curthread;
136	struct iovec *iov;
137	u_int cnt;
138	int error = 0;
139	int save = 0;
140
141	KASSERT(uio->uio_rw == UIO_READ || uio->uio_rw == UIO_WRITE,
142	    ("uiomove: mode"));
143	KASSERT(uio->uio_segflg != UIO_USERSPACE || uio->uio_td == curthread,
144	    ("uiomove proc"));
145	WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL,
146	    "Calling uiomove()");
147
148	save = td->td_pflags & TDP_DEADLKTREAT;
149	td->td_pflags |= TDP_DEADLKTREAT;
150
151	while (n > 0 && uio->uio_resid) {
152		iov = uio->uio_iov;
153		cnt = iov->iov_len;
154		if (cnt == 0) {
155			uio->uio_iov++;
156			uio->uio_iovcnt--;
157			continue;
158		}
159		if (cnt > n)
160			cnt = n;
161
162		switch (uio->uio_segflg) {
163
164		case UIO_USERSPACE:
165			if (ticks - PCPU_GET(switchticks) >= hogticks)
166				uio_yield();
167			if (uio->uio_rw == UIO_READ)
168				error = copyout(cp, iov->iov_base, cnt);
169			else
170				error = copyin(iov->iov_base, cp, cnt);
171			if (error)
172				goto out;
173			break;
174
175		case UIO_SYSSPACE:
176			if (uio->uio_rw == UIO_READ)
177				bcopy(cp, iov->iov_base, cnt);
178			else
179				bcopy(iov->iov_base, cp, cnt);
180			break;
181		case UIO_NOCOPY:
182			break;
183		}
184		iov->iov_base = (char *)iov->iov_base + cnt;
185		iov->iov_len -= cnt;
186		uio->uio_resid -= cnt;
187		uio->uio_offset += cnt;
188		cp = (char *)cp + cnt;
189		n -= cnt;
190	}
191out:
192	if (save == 0)
193		td->td_pflags &= ~TDP_DEADLKTREAT;
194	return (error);
195}
196
197/*
198 * Wrapper for uiomove() that validates the arguments against a known-good
199 * kernel buffer.  Currently, uiomove accepts a signed (n) argument, which
200 * is almost definitely a bad thing, so we catch that here as well.  We
201 * return a runtime failure, but it might be desirable to generate a runtime
202 * assertion failure instead.
203 */
204int
205uiomove_frombuf(void *buf, int buflen, struct uio *uio)
206{
207	unsigned int offset, n;
208
209	if (uio->uio_offset < 0 || uio->uio_resid < 0 ||
210	    (offset = uio->uio_offset) != uio->uio_offset)
211		return (EINVAL);
212	if (buflen <= 0 || offset >= buflen)
213		return (0);
214	if ((n = buflen - offset) > INT_MAX)
215		return (EINVAL);
216	return (uiomove((char *)buf + offset, n, uio));
217}
218
219#ifdef ZERO_COPY_SOCKETS
220/*
221 * Experimental support for zero-copy I/O
222 */
223static int
224userspaceco(void *cp, u_int cnt, struct uio *uio, int disposable)
225{
226	struct iovec *iov;
227	int error;
228
229	iov = uio->uio_iov;
230	if (uio->uio_rw == UIO_READ) {
231		if ((so_zero_copy_receive != 0)
232		 && ((cnt & PAGE_MASK) == 0)
233		 && ((((intptr_t) iov->iov_base) & PAGE_MASK) == 0)
234		 && ((uio->uio_offset & PAGE_MASK) == 0)
235		 && ((((intptr_t) cp) & PAGE_MASK) == 0)
236		 && (disposable != 0)) {
237			/* SOCKET: use page-trading */
238			/*
239			 * We only want to call vm_pgmoveco() on
240			 * disposeable pages, since it gives the
241			 * kernel page to the userland process.
242			 */
243			error =	vm_pgmoveco(&curproc->p_vmspace->vm_map,
244			    (vm_offset_t)cp, (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
264int
265uiomoveco(void *cp, int n, struct uio *uio, int disposable)
266{
267	struct iovec *iov;
268	u_int cnt;
269	int error;
270
271	KASSERT(uio->uio_rw == UIO_READ || uio->uio_rw == UIO_WRITE,
272	    ("uiomoveco: mode"));
273	KASSERT(uio->uio_segflg != UIO_USERSPACE || uio->uio_td == curthread,
274	    ("uiomoveco proc"));
275
276	while (n > 0 && uio->uio_resid) {
277		iov = uio->uio_iov;
278		cnt = iov->iov_len;
279		if (cnt == 0) {
280			uio->uio_iov++;
281			uio->uio_iovcnt--;
282			continue;
283		}
284		if (cnt > n)
285			cnt = n;
286
287		switch (uio->uio_segflg) {
288
289		case UIO_USERSPACE:
290			if (ticks - PCPU_GET(switchticks) >= hogticks)
291				uio_yield();
292
293			error = userspaceco(cp, cnt, uio, disposable);
294
295			if (error)
296				return (error);
297			break;
298
299		case UIO_SYSSPACE:
300			if (uio->uio_rw == UIO_READ)
301				bcopy(cp, iov->iov_base, cnt);
302			else
303				bcopy(iov->iov_base, cp, cnt);
304			break;
305		case UIO_NOCOPY:
306			break;
307		}
308		iov->iov_base = (char *)iov->iov_base + cnt;
309		iov->iov_len -= cnt;
310		uio->uio_resid -= cnt;
311		uio->uio_offset += cnt;
312		cp = (char *)cp + cnt;
313		n -= cnt;
314	}
315	return (0);
316}
317#endif /* ZERO_COPY_SOCKETS */
318
319/*
320 * Give next character to user as result of read.
321 */
322int
323ureadc(int c, struct uio *uio)
324{
325	struct iovec *iov;
326	char *iov_base;
327
328again:
329	if (uio->uio_iovcnt == 0 || uio->uio_resid == 0)
330		panic("ureadc");
331	iov = uio->uio_iov;
332	if (iov->iov_len == 0) {
333		uio->uio_iovcnt--;
334		uio->uio_iov++;
335		goto again;
336	}
337	switch (uio->uio_segflg) {
338
339	case UIO_USERSPACE:
340		if (subyte(iov->iov_base, c) < 0)
341			return (EFAULT);
342		break;
343
344	case UIO_SYSSPACE:
345		iov_base = iov->iov_base;
346		*iov_base = c;
347		iov->iov_base = iov_base;
348		break;
349
350	case UIO_NOCOPY:
351		break;
352	}
353	iov->iov_base = (char *)iov->iov_base + 1;
354	iov->iov_len--;
355	uio->uio_resid--;
356	uio->uio_offset++;
357	return (0);
358}
359
360/*
361 * General routine to allocate a hash table.
362 */
363void *
364hashinit(int elements, struct malloc_type *type, u_long *hashmask)
365{
366	long hashsize;
367	LIST_HEAD(generic, generic) *hashtbl;
368	int i;
369
370	if (elements <= 0)
371		panic("hashinit: bad elements");
372	for (hashsize = 1; hashsize <= elements; hashsize <<= 1)
373		continue;
374	hashsize >>= 1;
375	hashtbl = malloc((u_long)hashsize * sizeof(*hashtbl), type, M_WAITOK);
376	for (i = 0; i < hashsize; i++)
377		LIST_INIT(&hashtbl[i]);
378	*hashmask = hashsize - 1;
379	return (hashtbl);
380}
381
382void
383hashdestroy(void *vhashtbl, struct malloc_type *type, u_long hashmask)
384{
385	LIST_HEAD(generic, generic) *hashtbl, *hp;
386
387	hashtbl = vhashtbl;
388	for (hp = hashtbl; hp <= &hashtbl[hashmask]; hp++)
389		if (!LIST_EMPTY(hp))
390			panic("hashdestroy: hash not empty");
391	free(hashtbl, type);
392}
393
394static int primes[] = { 1, 13, 31, 61, 127, 251, 509, 761, 1021, 1531, 2039,
395			2557, 3067, 3583, 4093, 4603, 5119, 5623, 6143, 6653,
396			7159, 7673, 8191, 12281, 16381, 24571, 32749 };
397#define NPRIMES (sizeof(primes) / sizeof(primes[0]))
398
399/*
400 * General routine to allocate a prime number sized hash table.
401 */
402void *
403phashinit(int elements, struct malloc_type *type, u_long *nentries)
404{
405	long hashsize;
406	LIST_HEAD(generic, generic) *hashtbl;
407	int i;
408
409	if (elements <= 0)
410		panic("phashinit: bad elements");
411	for (i = 1, hashsize = primes[1]; hashsize <= elements;) {
412		i++;
413		if (i == NPRIMES)
414			break;
415		hashsize = primes[i];
416	}
417	hashsize = primes[i - 1];
418	hashtbl = malloc((u_long)hashsize * sizeof(*hashtbl), type, M_WAITOK);
419	for (i = 0; i < hashsize; i++)
420		LIST_INIT(&hashtbl[i]);
421	*nentries = hashsize;
422	return (hashtbl);
423}
424
425void
426uio_yield(void)
427{
428	struct thread *td;
429
430	td = curthread;
431	mtx_lock_spin(&sched_lock);
432	DROP_GIANT();
433#ifdef KSE
434	sched_prio(td, td->td_ksegrp->kg_user_pri); /* XXXKSE */
435#else
436	sched_prio(td, td->td_user_pri);
437#endif
438	mi_switch(SW_INVOL, NULL);
439	mtx_unlock_spin(&sched_lock);
440	PICKUP_GIANT();
441}
442
443int
444copyinfrom(const void * __restrict src, void * __restrict dst, size_t len,
445    int seg)
446{
447	int error = 0;
448
449	switch (seg) {
450	case UIO_USERSPACE:
451		error = copyin(src, dst, len);
452		break;
453	case UIO_SYSSPACE:
454		bcopy(src, dst, len);
455		break;
456	default:
457		panic("copyinfrom: bad seg %d\n", seg);
458	}
459	return (error);
460}
461
462int
463copyinstrfrom(const void * __restrict src, void * __restrict dst, size_t len,
464    size_t * __restrict copied, int seg)
465{
466	int error = 0;
467
468	switch (seg) {
469	case UIO_USERSPACE:
470		error = copyinstr(src, dst, len, copied);
471		break;
472	case UIO_SYSSPACE:
473		error = copystr(src, dst, len, copied);
474		break;
475	default:
476		panic("copyinstrfrom: bad seg %d\n", seg);
477	}
478	return (error);
479}
480
481int
482copyiniov(struct iovec *iovp, u_int iovcnt, struct iovec **iov, int error)
483{
484	u_int iovlen;
485
486	*iov = NULL;
487	if (iovcnt > UIO_MAXIOV)
488		return (error);
489	iovlen = iovcnt * sizeof (struct iovec);
490	*iov = malloc(iovlen, M_IOV, M_WAITOK);
491	error = copyin(iovp, *iov, iovlen);
492	if (error) {
493		free(*iov, M_IOV);
494		*iov = NULL;
495	}
496	return (error);
497}
498
499int
500copyinuio(struct iovec *iovp, u_int iovcnt, struct uio **uiop)
501{
502	struct iovec *iov;
503	struct uio *uio;
504	u_int iovlen;
505	int error, i;
506
507	*uiop = NULL;
508	if (iovcnt > UIO_MAXIOV)
509		return (EINVAL);
510	iovlen = iovcnt * sizeof (struct iovec);
511	uio = malloc(iovlen + sizeof *uio, M_IOV, M_WAITOK);
512	iov = (struct iovec *)(uio + 1);
513	error = copyin(iovp, iov, iovlen);
514	if (error) {
515		free(uio, M_IOV);
516		return (error);
517	}
518	uio->uio_iov = iov;
519	uio->uio_iovcnt = iovcnt;
520	uio->uio_segflg = UIO_USERSPACE;
521	uio->uio_offset = -1;
522	uio->uio_resid = 0;
523	for (i = 0; i < iovcnt; i++) {
524		if (iov->iov_len > INT_MAX - uio->uio_resid) {
525			free(uio, M_IOV);
526			return (EINVAL);
527		}
528		uio->uio_resid += iov->iov_len;
529		iov++;
530	}
531	*uiop = uio;
532	return (0);
533}
534
535struct uio *
536cloneuio(struct uio *uiop)
537{
538	struct uio *uio;
539	int iovlen;
540
541	iovlen = uiop->uio_iovcnt * sizeof (struct iovec);
542	uio = malloc(iovlen + sizeof *uio, M_IOV, M_WAITOK);
543	*uio = *uiop;
544	uio->uio_iov = (struct iovec *)(uio + 1);
545	bcopy(uiop->uio_iov, uio->uio_iov, iovlen);
546	return (uio);
547}
548