procfs_mem.c revision 22975 
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	8.5 (Berkeley) 6/15/94
39 *
40 *	$Id$
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_param.h>
57#include <vm/vm_prot.h>
58#include <sys/lock.h>
59#include <vm/pmap.h>
60#include <vm/vm_map.h>
61#include <vm/vm_kern.h>
62#include <vm/vm_object.h>
63#include <vm/vm_page.h>
64#include <vm/vm_extern.h>
65#include <sys/user.h>
66
67static int	procfs_rwmem __P((struct proc *p, struct uio *uio));
68
69static int
70procfs_rwmem(p, uio)
71	struct proc *p;
72	struct uio *uio;
73{
74	int error;
75	int writing;
76	struct vmspace *vm;
77	int fix_prot = 0;
78	vm_map_t map;
79	vm_object_t object = NULL;
80	vm_offset_t pageno = 0;		/* page number */
81
82	/*
83	 * if the vmspace is in the midst of being deallocated or the
84	 * process is exiting, don't try to grab anything.  The page table
85	 * usage in that process can be messed up.
86	 */
87	vm = p->p_vmspace;
88	if ((p->p_flag & P_WEXIT) || (vm->vm_refcnt < 1))
89		return EFAULT;
90	++vm->vm_refcnt;
91	/*
92	 * The map we want...
93	 */
94	map = &vm->vm_map;
95
96	writing = uio->uio_rw == UIO_WRITE;
97
98	/*
99	 * Only map in one page at a time.  We don't have to, but it
100	 * makes things easier.  This way is trivial - right?
101	 */
102	do {
103		vm_map_t tmap;
104		vm_offset_t kva = 0;
105		vm_offset_t uva;
106		int page_offset;		/* offset into page */
107		vm_map_entry_t out_entry;
108		vm_prot_t out_prot;
109		boolean_t wired, single_use;
110		vm_pindex_t pindex;
111		u_int len;
112
113		fix_prot = 0;
114		object = NULL;
115
116		uva = (vm_offset_t) uio->uio_offset;
117
118		/*
119		 * Get the page number of this segment.
120		 */
121		pageno = trunc_page(uva);
122		page_offset = uva - pageno;
123
124		/*
125		 * How many bytes to copy
126		 */
127		len = min(PAGE_SIZE - page_offset, uio->uio_resid);
128
129		if (uva >= VM_MAXUSER_ADDRESS) {
130			if (writing || (uva >= (VM_MAXUSER_ADDRESS + UPAGES * PAGE_SIZE))) {
131				error = 0;
132				break;
133			}
134
135			/* we are reading the "U area", force it into core */
136			PHOLD(p);
137
138			/* sanity check */
139			if (!(p->p_flag & P_INMEM)) {
140				/* aiee! */
141				PRELE(p);
142				error = EFAULT;
143				break;
144			}
145
146			/* populate the ptrace/procfs area */
147			p->p_addr->u_kproc.kp_proc = *p;
148			fill_eproc (p, &p->p_addr->u_kproc.kp_eproc);
149
150			/* locate the in-core address */
151			kva = (u_int)p->p_addr + uva - VM_MAXUSER_ADDRESS;
152
153			/* transfer it */
154			error = uiomove((caddr_t)kva, len, uio);
155
156			/* let the pages go */
157			PRELE(p);
158
159			continue;
160		}
161
162		/*
163		 * Check the permissions for the area we're interested
164		 * in.
165		 */
166		if (writing) {
167			fix_prot = !vm_map_check_protection(map, pageno,
168					pageno + PAGE_SIZE, VM_PROT_WRITE);
169
170			if (fix_prot) {
171				/*
172				 * If the page is not writable, we make it so.
173				 * XXX It is possible that a page may *not* be
174				 * read/executable, if a process changes that!
175				 * We will assume, for now, that a page is either
176				 * VM_PROT_ALL, or VM_PROT_READ|VM_PROT_EXECUTE.
177				 */
178				error = vm_map_protect(map, pageno,
179					pageno + PAGE_SIZE, VM_PROT_ALL, 0);
180				if (error) {
181					/*
182					 * We don't have to undo something
183					 * that didn't work, so we clear the
184					 * flag.
185					 */
186					fix_prot = 0;
187					break;
188				}
189			}
190		}
191
192		/*
193		 * Now we need to get the page.  out_entry, out_prot, wired,
194		 * and single_use aren't used.  One would think the vm code
195		 * would be a *bit* nicer...  We use tmap because
196		 * vm_map_lookup() can change the map argument.
197		 */
198		tmap = map;
199		error = vm_map_lookup(&tmap, pageno,
200			      writing ? VM_PROT_WRITE : VM_PROT_READ,
201			      &out_entry, &object, &pindex, &out_prot,
202			      &wired, &single_use);
203
204		if (error) {
205			/*
206			 * Make sure that there is no residue in 'object' from
207			 * an error return on vm_map_lookup.
208			 */
209			object = NULL;
210			break;
211		}
212
213		/*
214		 * We're done with tmap now.
215		 * But reference the object first, so that we won't loose
216		 * it.
217		 */
218		vm_object_reference(object);
219		vm_map_lookup_done(tmap, out_entry);
220
221		/*
222		 * Fault the page in...
223		 */
224		if (writing && object->backing_object) {
225			error = vm_fault(map, pageno,
226				VM_PROT_WRITE, FALSE);
227			if (error)
228				break;
229		}
230
231		/* Find space in kernel_map for the page we're interested in */
232		error = vm_map_find(kernel_map, object,
233				IDX_TO_OFF(pindex), &kva, PAGE_SIZE, 1,
234				VM_PROT_ALL, VM_PROT_ALL, 0);
235		if (error) {
236			break;
237		}
238
239		/*
240		 * Mark the page we just found as pageable.
241		 */
242		error = vm_map_pageable(kernel_map, kva,
243				kva + PAGE_SIZE, 0);
244		if (error) {
245			vm_map_remove(kernel_map, kva, kva + PAGE_SIZE);
246			object = NULL;
247			break;
248		}
249
250		/*
251		 * Now do the i/o move.
252		 */
253		error = uiomove((caddr_t)(kva + page_offset),
254				len, uio);
255
256		/*
257		 * vm_map_remove gets rid of the object reference, so
258		 * we need to get rid of our 'object' pointer if there
259		 * is subsequently an error.
260		 */
261		vm_map_remove(kernel_map, kva, kva + PAGE_SIZE);
262		object = NULL;
263
264		/*
265		 * Undo the protection 'damage'.
266		 */
267		if (fix_prot) {
268			vm_map_protect(map, pageno, pageno + PAGE_SIZE,
269				VM_PROT_READ|VM_PROT_EXECUTE, 0);
270			fix_prot = 0;
271		}
272	} while (error == 0 && uio->uio_resid > 0);
273
274	if (object)
275		vm_object_deallocate(object);
276
277	if (fix_prot)
278		vm_map_protect(map, pageno, pageno + PAGE_SIZE,
279				VM_PROT_READ|VM_PROT_EXECUTE, 0);
280
281	vmspace_free(vm);
282	return (error);
283}
284
285/*
286 * Copy data in and out of the target process.
287 * We do this by mapping the process's page into
288 * the kernel and then doing a uiomove direct
289 * from the kernel address space.
290 */
291int
292procfs_domem(curp, p, pfs, uio)
293	struct proc *curp;
294	struct proc *p;
295	struct pfsnode *pfs;
296	struct uio *uio;
297{
298
299	if (uio->uio_resid == 0)
300		return (0);
301
302	return (procfs_rwmem(p, uio));
303}
304
305/*
306 * Given process (p), find the vnode from which
307 * it's text segment is being executed.
308 *
309 * It would be nice to grab this information from
310 * the VM system, however, there is no sure-fire
311 * way of doing that.  Instead, fork(), exec() and
312 * wait() all maintain the p_textvp field in the
313 * process proc structure which contains a held
314 * reference to the exec'ed vnode.
315 */
316struct vnode *
317procfs_findtextvp(p)
318	struct proc *p;
319{
320
321	return (p->p_textvp);
322}
323