uio_machdep.c revision 128019 
1/*
2 * Copyright (c) 2004 Alan L. Cox <alc@cs.rice.edu>
3 * Copyright (c) 1982, 1986, 1991, 1993
4 *	The Regents of the University of California.  All rights reserved.
5 * (c) UNIX System Laboratories, Inc.
6 * All or some portions of this file are derived from material licensed
7 * to the University of California by American Telephone and Telegraph
8 * Co. or Unix System Laboratories, Inc. and are reproduced herein with
9 * the permission of UNIX System Laboratories, Inc.
10 *
11 * Redistribution and use in source and binary forms, with or without
12 * modification, are permitted provided that the following conditions
13 * are met:
14 * 1. Redistributions of source code must retain the above copyright
15 *    notice, this list of conditions and the following disclaimer.
16 * 2. Redistributions in binary form must reproduce the above copyright
17 *    notice, this list of conditions and the following disclaimer in the
18 *    documentation and/or other materials provided with the distribution.
19 * 4. Neither the name of the University nor the names of its contributors
20 *    may be used to endorse or promote products derived from this software
21 *    without specific prior written permission.
22 *
23 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33 * SUCH DAMAGE.
34 *
35 *	@(#)kern_subr.c	8.3 (Berkeley) 1/21/94
36 */
37
38#include <sys/cdefs.h>
39__FBSDID("$FreeBSD: head/sys/i386/i386/uio_machdep.c 128019 2004-04-07 20:46:16Z imp $");
40
41#include <sys/param.h>
42#include <sys/kernel.h>
43#include <sys/lock.h>
44#include <sys/mutex.h>
45#include <sys/proc.h>
46#include <sys/sf_buf.h>
47#include <sys/systm.h>
48#include <sys/uio.h>
49
50#include <vm/vm.h>
51#include <vm/vm_page.h>
52
53/*
54 * Implement uiomove(9) from physical memory using sf_bufs to reduce
55 * the creation and destruction of ephemeral mappings.
56 */
57int
58uiomove_fromphys(vm_page_t ma[], vm_offset_t offset, int n, struct uio *uio)
59{
60	struct sf_buf *sf;
61	struct thread *td = curthread;
62	struct iovec *iov;
63	void *cp;
64	vm_offset_t page_offset;
65	size_t cnt;
66	int error = 0;
67	int save = 0;
68
69	KASSERT(uio->uio_rw == UIO_READ || uio->uio_rw == UIO_WRITE,
70	    ("uiomove_fromphys: mode"));
71	KASSERT(uio->uio_segflg != UIO_USERSPACE || uio->uio_td == curthread,
72	    ("uiomove_fromphys proc"));
73	if (td != NULL) {
74		mtx_lock_spin(&sched_lock);
75		save = td->td_flags & TDF_DEADLKTREAT;
76		td->td_flags |= TDF_DEADLKTREAT;
77		mtx_unlock_spin(&sched_lock);
78	}
79	while (n > 0 && uio->uio_resid) {
80		iov = uio->uio_iov;
81		cnt = iov->iov_len;
82		if (cnt == 0) {
83			uio->uio_iov++;
84			uio->uio_iovcnt--;
85			continue;
86		}
87		if (cnt > n)
88			cnt = n;
89		page_offset = offset & PAGE_MASK;
90		cnt = min(cnt, PAGE_SIZE - page_offset);
91		sf = sf_buf_alloc(ma[offset >> PAGE_SHIFT], 0);
92		cp = (char *)sf_buf_kva(sf) + page_offset;
93		switch (uio->uio_segflg) {
94		case UIO_USERSPACE:
95			if (ticks - PCPU_GET(switchticks) >= hogticks)
96				uio_yield();
97			if (uio->uio_rw == UIO_READ)
98				error = copyout(cp, iov->iov_base, cnt);
99			else
100				error = copyin(iov->iov_base, cp, cnt);
101			if (error)
102				goto out;
103			break;
104		case UIO_SYSSPACE:
105			if (uio->uio_rw == UIO_READ)
106				bcopy(cp, iov->iov_base, cnt);
107			else
108				bcopy(iov->iov_base, cp, cnt);
109			break;
110		case UIO_NOCOPY:
111			break;
112		}
113		sf_buf_free(sf);
114		iov->iov_base = (char *)iov->iov_base + cnt;
115		iov->iov_len -= cnt;
116		uio->uio_resid -= cnt;
117		uio->uio_offset += cnt;
118		offset += cnt;
119		n -= cnt;
120	}
121out:
122	if (td != NULL && save == 0) {
123		mtx_lock_spin(&sched_lock);
124		td->td_flags &= ~TDF_DEADLKTREAT;
125		mtx_unlock_spin(&sched_lock);
126	}
127	return (error);
128}
129