procfs_mem.c revision 9346 
1/*
2 * Copyright (c) 1993 Jan-Simon Pendry
3 * Copyright (c) 1993 Sean Eric Fagan
4 * Copyright (c) 1993
5 *	The Regents of the University of California.  All rights reserved.
6 *
7 * This code is derived from software contributed to Berkeley by
8 * Jan-Simon Pendry and Sean Eric Fagan.
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 *	@(#)procfs_mem.c	8.4 (Berkeley) 1/21/94
39 *
40 *	$Id: procfs_mem.c,v 1.7 1995/05/30 08:07:09 rgrimes Exp $
41 */
42
43/*
44 * This is a lightly hacked and merged version
45 * of sef's pread/pwrite functions
46 */
47
48#include <sys/param.h>
49#include <sys/systm.h>
50#include <sys/time.h>
51#include <sys/kernel.h>
52#include <sys/proc.h>
53#include <sys/vnode.h>
54#include <miscfs/procfs/procfs.h>
55#include <vm/vm.h>
56#include <vm/vm_kern.h>
57#include <vm/vm_page.h>
58
59static int
60procfs_rwmem(p, uio)
61	struct proc *p;
62	struct uio *uio;
63{
64	int error;
65	int writing;
66
67	writing = uio->uio_rw == UIO_WRITE;
68
69	/*
70	 * Only map in one page at a time.  We don't have to, but it
71	 * makes things easier.  This way is trivial - right?
72	 */
73	do {
74		vm_map_t map, tmap;
75		vm_object_t object;
76		vm_offset_t kva = 0;
77		vm_offset_t uva;
78		int page_offset;		/* offset into page */
79		vm_offset_t pageno;		/* page number */
80		vm_map_entry_t out_entry;
81		vm_prot_t out_prot;
82		vm_page_t m;
83		boolean_t wired, single_use;
84		vm_offset_t off;
85		u_int len;
86		int fix_prot;
87
88		uva = (vm_offset_t) uio->uio_offset;
89		if (uva >= VM_MAXUSER_ADDRESS) {
90			if (writing || (uva >= (VM_MAXUSER_ADDRESS + UPAGES * PAGE_SIZE))) {
91				error = 0;
92				break;
93			}
94		}
95
96		/*
97		 * Get the page number of this segment.
98		 */
99		pageno = trunc_page(uva);
100		page_offset = uva - pageno;
101
102		/*
103		 * How many bytes to copy
104		 */
105		len = min(PAGE_SIZE - page_offset, uio->uio_resid);
106
107		/*
108		 * The map we want...
109		 */
110		map = &p->p_vmspace->vm_map;
111
112		/*
113		 * Check the permissions for the area we're interested
114		 * in.
115		 */
116		fix_prot = 0;
117		if (writing)
118			fix_prot = !vm_map_check_protection(map, pageno,
119					pageno + PAGE_SIZE, VM_PROT_WRITE);
120
121		if (fix_prot) {
122			/*
123			 * If the page is not writable, we make it so.
124			 * XXX It is possible that a page may *not* be
125			 * read/executable, if a process changes that!
126			 * We will assume, for now, that a page is either
127			 * VM_PROT_ALL, or VM_PROT_READ|VM_PROT_EXECUTE.
128			 */
129			error = vm_map_protect(map, pageno,
130					pageno + PAGE_SIZE, VM_PROT_ALL, 0);
131			if (error)
132				break;
133		}
134
135		/*
136		 * Now we need to get the page.  out_entry, out_prot, wired,
137		 * and single_use aren't used.  One would think the vm code
138		 * would be a *bit* nicer...  We use tmap because
139		 * vm_map_lookup() can change the map argument.
140		 */
141		tmap = map;
142		error = vm_map_lookup(&tmap, pageno,
143				      writing ? VM_PROT_WRITE : VM_PROT_READ,
144				      &out_entry, &object, &off, &out_prot,
145				      &wired, &single_use);
146		/*
147		 * We're done with tmap now.
148		 */
149		if (!error)
150			vm_map_lookup_done(tmap, out_entry);
151
152		/*
153		 * Fault the page in...
154		 */
155		if (!error && writing && object->shadow) {
156			m = vm_page_lookup(object, off);
157			if (m == 0 || (m->flags & PG_COPYONWRITE))
158				error = vm_fault(map, pageno,
159							VM_PROT_WRITE, FALSE);
160		}
161
162		/* Find space in kernel_map for the page we're interested in */
163		if (!error)
164			error = vm_map_find(kernel_map, object, off, &kva,
165					PAGE_SIZE, 1);
166
167		if (!error) {
168			/*
169			 * Neither vm_map_lookup() nor vm_map_find() appear
170			 * to add a reference count to the object, so we do
171			 * that here and now.
172			 */
173			vm_object_reference(object);
174
175			/*
176			 * Mark the page we just found as pageable.
177			 */
178			error = vm_map_pageable(kernel_map, kva,
179				kva + PAGE_SIZE, 0);
180
181			/*
182			 * Now do the i/o move.
183			 */
184			if (!error)
185				error = uiomove((caddr_t)(kva + page_offset),
186						len, uio);
187
188			vm_map_remove(kernel_map, kva, kva + PAGE_SIZE);
189		}
190		if (fix_prot)
191			vm_map_protect(map, pageno, pageno + PAGE_SIZE,
192					VM_PROT_READ|VM_PROT_EXECUTE, 0);
193	} while (error == 0 && uio->uio_resid > 0);
194
195	return (error);
196}
197
198/*
199 * Copy data in and out of the target process.
200 * We do this by mapping the process's page into
201 * the kernel and then doing a uiomove direct
202 * from the kernel address space.
203 */
204int
205procfs_domem(curp, p, pfs, uio)
206	struct proc *curp;
207	struct proc *p;
208	struct pfsnode *pfs;
209	struct uio *uio;
210{
211	int error;
212
213	if (uio->uio_resid == 0)
214		return (0);
215
216	error = procfs_rwmem(p, uio);
217
218	return (error);
219}
220
221/*
222 * Given process (p), find the vnode from which
223 * it's text segment is being executed.
224 *
225 * It would be nice to grab this information from
226 * the VM system, however, there is no sure-fire
227 * way of doing that.  Instead, fork(), exec() and
228 * wait() all maintain the p_textvp field in the
229 * process proc structure which contains a held
230 * reference to the exec'ed vnode.
231 */
232struct vnode *
233procfs_findtextvp(p)
234	struct proc *p;
235{
236	return (p->p_textvp);
237}
238