uipc_cow.c revision 112316 
1/*-
2 * Copyright (c) 1997, Duke University
3 * All rights reserved.
4 *
5 * Author:
6 *         Andrew Gallatin <gallatin@cs.duke.edu>
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 *    notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 *    notice, this list of conditions and the following disclaimer in the
15 *    documentation and/or other materials provided with the distribution.
16 * 3. The name of Duke University may not be used to endorse or promote
17 *    products derived from this software without specific prior written
18 *    permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY DUKE UNIVERSITY ``AS IS'' AND ANY
21 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
23 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL DUKE UNIVERSITY BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
25 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
26 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITSOR BUSINESS
27 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER
28 * IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
29 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
30 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
31 *
32 * $FreeBSD: head/sys/kern/uipc_cow.c 112316 2003-03-16 07:19:12Z alc $
33 */
34/*
35 * This is a set of routines for enabling and disabling copy on write
36 * protection for data written into sockets.
37 */
38
39#include <sys/param.h>
40#include <sys/systm.h>
41#include <sys/kernel.h>
42#include <sys/proc.h>
43#include <sys/lock.h>
44#include <sys/mutex.h>
45#include <sys/mbuf.h>
46#include <sys/socketvar.h>
47#include <sys/uio.h>
48
49#include <vm/vm.h>
50#include <vm/vm_param.h>
51#include <vm/pmap.h>
52#include <vm/vm_map.h>
53#include <vm/vm_page.h>
54#include <vm/vm_object.h>
55#if 0
56#include <vm/vm_pager.h>
57#include <vm/vm_kern.h>
58#include <vm/vm_extern.h>
59#include <vm/vm_zone.h>
60#include <vm/swap_pager.h>
61#endif
62
63
64struct netsend_cow_stats {
65	int attempted;
66	int fail_not_mapped;
67	int fail_wired;
68	int fail_not_anon;
69	int fail_pmap_cow;
70	int fail_pg_error;
71	int fail_kva;
72	int free_post_exit;
73	int success;
74	int iodone;
75	int freed;
76};
77
78static struct netsend_cow_stats socow_stats = {0,0,0,0,0,0,0,0,0,0,0};
79
80static void socow_iodone(void *addr, void *args);
81
82static void
83socow_iodone(void *addr, void *args)
84{
85	int s;
86	struct sf_buf *sf;
87	vm_page_t pp;
88
89	sf = args;
90	pp = sf->m;
91	s = splvm();
92	/* remove COW mapping  */
93	vm_page_lock_queues();
94	vm_page_cowclear(pp);
95	vm_page_unlock_queues();
96	splx(s);
97	/* note that sf_buf_free() unwires the page for us*/
98	sf_buf_free(addr, args);
99	socow_stats.iodone++;
100}
101
102int
103socow_setup(struct mbuf *m0, struct uio *uio)
104{
105	struct sf_buf *sf;
106	vm_page_t pp;
107	vm_offset_t pa;
108	struct iovec *iov;
109	struct vmspace *vmspace;
110	struct vm_map *map;
111	vm_offset_t uva;
112	int s;
113
114	vmspace = curproc->p_vmspace;;
115	map = &vmspace->vm_map;
116	uva = (vm_offset_t) uio->uio_iov->iov_base;
117
118	s = splvm();
119
120       /*
121	* verify page is mapped & not already wired for i/o
122	*/
123	socow_stats.attempted++;
124	pa=pmap_extract(map->pmap, uva);
125	if(!pa) {
126		socow_stats.fail_not_mapped++;
127		splx(s);
128		return(0);
129	}
130	pp = PHYS_TO_VM_PAGE(pa);
131
132	sf = sf_buf_alloc();
133	sf->m = pp;
134	pmap_qenter(sf->kva, &pp, 1);
135
136	/*
137	 * set up COW
138	 */
139	vm_page_lock_queues();
140	vm_page_cowsetup(pp);
141
142	/*
143	 * wire the page for I/O
144	 */
145	vm_page_wire(pp);
146	vm_page_unlock_queues();
147
148	/*
149	 * attach to mbuf
150	 */
151	m0->m_data = (caddr_t)sf->kva;
152	m0->m_len = PAGE_SIZE;
153	MEXTADD(m0, sf->kva, PAGE_SIZE, socow_iodone, sf, 0, EXT_SFBUF);
154	socow_stats.success++;
155
156	iov = uio->uio_iov;
157	iov->iov_base = (char *)iov->iov_base + PAGE_SIZE;
158	iov->iov_len -= PAGE_SIZE;
159	uio->uio_resid -= PAGE_SIZE;
160	uio->uio_offset += PAGE_SIZE;
161	if (iov->iov_len == 0) {
162		uio->uio_iov++;
163		uio->uio_iovcnt--;
164	}
165
166	splx(s);
167	return(1);
168}
169