subr_hash.c revision 131473 
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 131473 2004-07-02 19:09:50Z jhb $");
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
71static int
72vm_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
128int
129uiomove(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	}
185out:
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 */
198int
199uiomove_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 */
217static int
218userspaceco(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
262int
263uiomoveco(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 */
321int
322ureadc(int c, struct uio *uio)
323{
324	struct iovec *iov;
325	char *iov_base;
326
327again:
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 */
362void *
363hashinit(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
381void
382hashdestroy(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
393static 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 */
401void *
402phashinit(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
424void
425uio_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
438int
439copyinfrom(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
457int
458copyinstrfrom(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
476int
477uiofromiov(struct iovec *iovp, u_int iovcnt, struct uio *uio)
478{
479	struct iovec *iov;
480	u_int iovlen;
481	int error, i;
482
483	/* note: can't use iovlen until iovcnt is validated */
484	iovlen = iovcnt * sizeof (struct iovec);
485	if (iovcnt > UIO_MAXIOV) {
486		error = EINVAL;
487		goto done;
488	}
489	MALLOC(iov, struct iovec *, iovlen, M_IOV, M_WAITOK);
490	uio->uio_iov = iov;
491	uio->uio_iovcnt = iovcnt;
492	uio->uio_segflg = UIO_USERSPACE;
493	uio->uio_offset = -1;
494	if ((error = copyin(iovp, iov, iovlen)))
495		goto done;
496	uio->uio_resid = 0;
497	for (i = 0; i < iovcnt; i++) {
498		if (iov->iov_len > INT_MAX - uio->uio_resid) {
499			error = EINVAL;
500			goto done;
501		}
502		uio->uio_resid += iov->iov_len;
503		iov++;
504	}
505
506done:
507	if (error && uio->uio_iov) {
508		FREE(uio->uio_iov, M_IOV);
509		uio->uio_iov = NULL;
510	}
511	return (error);
512
513}
514