subr_hash.c revision 124944 
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 * 3. All advertising materials mentioning features or use of this software
19 *    must display the following acknowledgement:
20 *	This product includes software developed by the University of
21 *	California, Berkeley and its contributors.
22 * 4. Neither the name of the University nor the names of its contributors
23 *    may be used to endorse or promote products derived from this software
24 *    without specific prior written permission.
25 *
26 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
27 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
28 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
29 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
30 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
31 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
32 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
33 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
34 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
35 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
36 * SUCH DAMAGE.
37 *
38 *	@(#)kern_subr.c	8.3 (Berkeley) 1/21/94
39 */
40
41#include <sys/cdefs.h>
42__FBSDID("$FreeBSD: head/sys/kern/kern_subr.c 124944 2004-01-25 03:54:52Z jeff $");
43
44#include "opt_zero.h"
45
46#include <sys/param.h>
47#include <sys/systm.h>
48#include <sys/kernel.h>
49#include <sys/ktr.h>
50#include <sys/limits.h>
51#include <sys/lock.h>
52#include <sys/mutex.h>
53#include <sys/proc.h>
54#include <sys/malloc.h>
55#include <sys/resourcevar.h>
56#include <sys/sched.h>
57#include <sys/sysctl.h>
58#include <sys/vnode.h>
59
60#include <vm/vm.h>
61#include <vm/vm_page.h>
62#include <vm/vm_map.h>
63#ifdef ZERO_COPY_SOCKETS
64#include <vm/vm_param.h>
65#include <vm/vm_object.h>
66#endif
67
68SYSCTL_INT(_kern, KERN_IOV_MAX, iov_max, CTLFLAG_RD, NULL, UIO_MAXIOV,
69	"Maximum number of elements in an I/O vector; sysconf(_SC_IOV_MAX)");
70
71#ifdef ZERO_COPY_SOCKETS
72/* Declared in uipc_socket.c */
73extern int so_zero_copy_receive;
74
75static int
76vm_pgmoveco(vm_map_t mapa, vm_object_t srcobj, vm_offset_t kaddr,
77    vm_offset_t uaddr)
78{
79	vm_map_t map = mapa;
80	vm_page_t kern_pg, user_pg;
81	vm_object_t uobject;
82	vm_map_entry_t entry;
83	vm_pindex_t upindex, kpindex;
84	vm_prot_t prot;
85	boolean_t wired;
86
87	/*
88	 * First lookup the kernel page.
89	 */
90	kern_pg = PHYS_TO_VM_PAGE(vtophys(kaddr));
91	/*
92	 * XXX The vm object containing kern_pg needs locking.
93	 */
94	if ((vm_map_lookup(&map, uaddr,
95			   VM_PROT_WRITE, &entry, &uobject,
96			   &upindex, &prot, &wired)) != KERN_SUCCESS) {
97		return(EFAULT);
98	}
99	VM_OBJECT_LOCK(uobject);
100	if ((user_pg = vm_page_lookup(uobject, upindex)) != NULL) {
101		do
102			vm_page_lock_queues();
103		while (vm_page_sleep_if_busy(user_pg, 1, "vm_pgmoveco"));
104		vm_page_busy(user_pg);
105		pmap_remove_all(user_pg);
106		vm_page_free(user_pg);
107	} else
108		vm_page_lock_queues();
109	if (kern_pg->busy || ((kern_pg->queue - kern_pg->pc) == PQ_FREE) ||
110	    (kern_pg->hold_count != 0)|| (kern_pg->flags & PG_BUSY)) {
111		printf("vm_pgmoveco: pindex(%lu), busy(%d), PG_BUSY(%d), "
112		       "hold(%d) paddr(0x%lx)\n", (u_long)kern_pg->pindex,
113			kern_pg->busy, (kern_pg->flags & PG_BUSY) ? 1 : 0,
114			kern_pg->hold_count, (u_long)kern_pg->phys_addr);
115		if ((kern_pg->queue - kern_pg->pc) == PQ_FREE)
116			panic("vm_pgmoveco: renaming free page");
117		else
118			panic("vm_pgmoveco: renaming busy page");
119	}
120	kpindex = kern_pg->pindex;
121	vm_page_busy(kern_pg);
122	vm_page_rename(kern_pg, uobject, upindex);
123	vm_page_flag_clear(kern_pg, PG_BUSY);
124	kern_pg->valid = VM_PAGE_BITS_ALL;
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
146	if (td) {
147		mtx_lock_spin(&sched_lock);
148		save = td->td_flags & TDF_DEADLKTREAT;
149		td->td_flags |= TDF_DEADLKTREAT;
150		mtx_unlock_spin(&sched_lock);
151	}
152
153	while (n > 0 && uio->uio_resid) {
154		iov = uio->uio_iov;
155		cnt = iov->iov_len;
156		if (cnt == 0) {
157			uio->uio_iov++;
158			uio->uio_iovcnt--;
159			continue;
160		}
161		if (cnt > n)
162			cnt = n;
163
164		switch (uio->uio_segflg) {
165
166		case UIO_USERSPACE:
167			if (ticks - PCPU_GET(switchticks) >= hogticks)
168				uio_yield();
169			if (uio->uio_rw == UIO_READ)
170				error = copyout(cp, iov->iov_base, cnt);
171			else
172				error = copyin(iov->iov_base, cp, cnt);
173			if (error)
174				goto out;
175			break;
176
177		case UIO_SYSSPACE:
178			if (uio->uio_rw == UIO_READ)
179				bcopy(cp, iov->iov_base, cnt);
180			else
181				bcopy(iov->iov_base, cp, cnt);
182			break;
183		case UIO_NOCOPY:
184			break;
185		}
186		iov->iov_base = (char *)iov->iov_base + cnt;
187		iov->iov_len -= cnt;
188		uio->uio_resid -= cnt;
189		uio->uio_offset += cnt;
190		cp = (char *)cp + cnt;
191		n -= cnt;
192	}
193out:
194	if (td && save == 0) {
195		mtx_lock_spin(&sched_lock);
196		td->td_flags &= ~TDF_DEADLKTREAT;
197		mtx_unlock_spin(&sched_lock);
198	}
199	return (error);
200}
201
202/*
203 * Wrapper for uiomove() that validates the arguments against a known-good
204 * kernel buffer.  Currently, uiomove accepts a signed (n) argument, which
205 * is almost definitely a bad thing, so we catch that here as well.  We
206 * return a runtime failure, but it might be desirable to generate a runtime
207 * assertion failure instead.
208 */
209int
210uiomove_frombuf(void *buf, int buflen, struct uio *uio)
211{
212	unsigned int offset, n;
213
214	if (uio->uio_offset < 0 || uio->uio_resid < 0 ||
215	    (offset = uio->uio_offset) != uio->uio_offset)
216		return (EINVAL);
217	if (buflen <= 0 || offset >= buflen)
218		return (0);
219	if ((n = buflen - offset) > INT_MAX)
220		return (EINVAL);
221	return (uiomove((char *)buf + offset, n, uio));
222}
223
224#ifdef ZERO_COPY_SOCKETS
225/*
226 * Experimental support for zero-copy I/O
227 */
228static int
229userspaceco(void *cp, u_int cnt, struct uio *uio, struct vm_object *obj,
230    int disposable)
231{
232	struct iovec *iov;
233	int error;
234
235	iov = uio->uio_iov;
236	if (uio->uio_rw == UIO_READ) {
237		if ((so_zero_copy_receive != 0)
238		 && (obj != NULL)
239		 && ((cnt & PAGE_MASK) == 0)
240		 && ((((intptr_t) iov->iov_base) & PAGE_MASK) == 0)
241		 && ((uio->uio_offset & PAGE_MASK) == 0)
242		 && ((((intptr_t) cp) & PAGE_MASK) == 0)
243		 && (obj->type == OBJT_DEFAULT)
244		 && (disposable != 0)) {
245			/* SOCKET: use page-trading */
246			/*
247			 * We only want to call vm_pgmoveco() on
248			 * disposeable pages, since it gives the
249			 * kernel page to the userland process.
250			 */
251			error =	vm_pgmoveco(&curproc->p_vmspace->vm_map,
252					    obj, (vm_offset_t)cp,
253					    (vm_offset_t)iov->iov_base);
254
255			/*
256			 * If we get an error back, attempt
257			 * to use copyout() instead.  The
258			 * disposable page should be freed
259			 * automatically if we weren't able to move
260			 * it into userland.
261			 */
262			if (error != 0)
263				error = copyout(cp, iov->iov_base, cnt);
264		} else {
265			error = copyout(cp, iov->iov_base, cnt);
266		}
267	} else {
268		error = copyin(iov->iov_base, cp, cnt);
269	}
270	return (error);
271}
272
273int
274uiomoveco(void *cp, int n, struct uio *uio, struct vm_object *obj,
275    int disposable)
276{
277	struct iovec *iov;
278	u_int cnt;
279	int error;
280
281	KASSERT(uio->uio_rw == UIO_READ || uio->uio_rw == UIO_WRITE,
282	    ("uiomoveco: mode"));
283	KASSERT(uio->uio_segflg != UIO_USERSPACE || uio->uio_td == curthread,
284	    ("uiomoveco proc"));
285
286	while (n > 0 && uio->uio_resid) {
287		iov = uio->uio_iov;
288		cnt = iov->iov_len;
289		if (cnt == 0) {
290			uio->uio_iov++;
291			uio->uio_iovcnt--;
292			continue;
293		}
294		if (cnt > n)
295			cnt = n;
296
297		switch (uio->uio_segflg) {
298
299		case UIO_USERSPACE:
300			if (ticks - PCPU_GET(switchticks) >= hogticks)
301				uio_yield();
302
303			error = userspaceco(cp, cnt, uio, obj, disposable);
304
305			if (error)
306				return (error);
307			break;
308
309		case UIO_SYSSPACE:
310			if (uio->uio_rw == UIO_READ)
311				bcopy(cp, iov->iov_base, cnt);
312			else
313				bcopy(iov->iov_base, cp, cnt);
314			break;
315		case UIO_NOCOPY:
316			break;
317		}
318		iov->iov_base = (char *)iov->iov_base + cnt;
319		iov->iov_len -= cnt;
320		uio->uio_resid -= cnt;
321		uio->uio_offset += cnt;
322		cp = (char *)cp + cnt;
323		n -= cnt;
324	}
325	return (0);
326}
327#endif /* ZERO_COPY_SOCKETS */
328
329/*
330 * Give next character to user as result of read.
331 */
332int
333ureadc(int c, struct uio *uio)
334{
335	struct iovec *iov;
336	char *iov_base;
337
338again:
339	if (uio->uio_iovcnt == 0 || uio->uio_resid == 0)
340		panic("ureadc");
341	iov = uio->uio_iov;
342	if (iov->iov_len == 0) {
343		uio->uio_iovcnt--;
344		uio->uio_iov++;
345		goto again;
346	}
347	switch (uio->uio_segflg) {
348
349	case UIO_USERSPACE:
350		if (subyte(iov->iov_base, c) < 0)
351			return (EFAULT);
352		break;
353
354	case UIO_SYSSPACE:
355		iov_base = iov->iov_base;
356		*iov_base = c;
357		iov->iov_base = iov_base;
358		break;
359
360	case UIO_NOCOPY:
361		break;
362	}
363	iov->iov_base = (char *)iov->iov_base + 1;
364	iov->iov_len--;
365	uio->uio_resid--;
366	uio->uio_offset++;
367	return (0);
368}
369
370/*
371 * General routine to allocate a hash table.
372 */
373void *
374hashinit(int elements, struct malloc_type *type, u_long *hashmask)
375{
376	long hashsize;
377	LIST_HEAD(generic, generic) *hashtbl;
378	int i;
379
380	if (elements <= 0)
381		panic("hashinit: bad elements");
382	for (hashsize = 1; hashsize <= elements; hashsize <<= 1)
383		continue;
384	hashsize >>= 1;
385	hashtbl = malloc((u_long)hashsize * sizeof(*hashtbl), type, M_WAITOK);
386	for (i = 0; i < hashsize; i++)
387		LIST_INIT(&hashtbl[i]);
388	*hashmask = hashsize - 1;
389	return (hashtbl);
390}
391
392void
393hashdestroy(void *vhashtbl, struct malloc_type *type, u_long hashmask)
394{
395	LIST_HEAD(generic, generic) *hashtbl, *hp;
396
397	hashtbl = vhashtbl;
398	for (hp = hashtbl; hp <= &hashtbl[hashmask]; hp++)
399		if (!LIST_EMPTY(hp))
400			panic("hashdestroy: hash not empty");
401	free(hashtbl, type);
402}
403
404static int primes[] = { 1, 13, 31, 61, 127, 251, 509, 761, 1021, 1531, 2039,
405			2557, 3067, 3583, 4093, 4603, 5119, 5623, 6143, 6653,
406			7159, 7673, 8191, 12281, 16381, 24571, 32749 };
407#define NPRIMES (sizeof(primes) / sizeof(primes[0]))
408
409/*
410 * General routine to allocate a prime number sized hash table.
411 */
412void *
413phashinit(int elements, struct malloc_type *type, u_long *nentries)
414{
415	long hashsize;
416	LIST_HEAD(generic, generic) *hashtbl;
417	int i;
418
419	if (elements <= 0)
420		panic("phashinit: bad elements");
421	for (i = 1, hashsize = primes[1]; hashsize <= elements;) {
422		i++;
423		if (i == NPRIMES)
424			break;
425		hashsize = primes[i];
426	}
427	hashsize = primes[i - 1];
428	hashtbl = malloc((u_long)hashsize * sizeof(*hashtbl), type, M_WAITOK);
429	for (i = 0; i < hashsize; i++)
430		LIST_INIT(&hashtbl[i]);
431	*nentries = hashsize;
432	return (hashtbl);
433}
434
435void
436uio_yield(void)
437{
438	struct thread *td;
439
440	td = curthread;
441	mtx_lock_spin(&sched_lock);
442	DROP_GIANT();
443	sched_prio(td, td->td_ksegrp->kg_user_pri); /* XXXKSE */
444	mi_switch(SW_INVOL);
445	mtx_unlock_spin(&sched_lock);
446	PICKUP_GIANT();
447}
448
449int
450copyinfrom(const void * __restrict src, void * __restrict dst, size_t len,
451    int seg)
452{
453	int error = 0;
454
455	switch (seg) {
456	case UIO_USERSPACE:
457		error = copyin(src, dst, len);
458		break;
459	case UIO_SYSSPACE:
460		bcopy(src, dst, len);
461		break;
462	default:
463		panic("copyinfrom: bad seg %d\n", seg);
464	}
465	return (error);
466}
467
468int
469copyinstrfrom(const void * __restrict src, void * __restrict dst, size_t len,
470    size_t * __restrict copied, int seg)
471{
472	int error = 0;
473
474	switch (seg) {
475	case UIO_USERSPACE:
476		error = copyinstr(src, dst, len, copied);
477		break;
478	case UIO_SYSSPACE:
479		error = copystr(src, dst, len, copied);
480		break;
481	default:
482		panic("copyinstrfrom: bad seg %d\n", seg);
483	}
484	return (error);
485}
486