kernel - Major signal path adjustments to fix races, tsleep race fixes, +more
[dragonfly.git] / sys / vfs / procfs / procfs_mem.c
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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 * $FreeBSD: src/sys/miscfs/procfs/procfs_mem.c,v 1.46.2.3 2002/01/22 17:22:59 nectar Exp $
e3161323 41 * $DragonFly: src/sys/vfs/procfs/procfs_mem.c,v 1.16 2007/04/29 18:25:40 dillon Exp $
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42 */
43
44/*
45 * This is a lightly hacked and merged version
46 * of sef's pread/pwrite functions
47 */
48
49#include <sys/param.h>
50#include <sys/systm.h>
51#include <sys/proc.h>
75bda2d9 52#include <sys/priv.h>
984263bc 53#include <sys/vnode.h>
1f2de5d4 54#include <vfs/procfs/procfs.h>
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55#include <vm/vm.h>
56#include <vm/vm_param.h>
57#include <sys/lock.h>
58#include <vm/pmap.h>
59#include <vm/vm_extern.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 <sys/user.h>
65#include <sys/ptrace.h>
66
654a39f0 67#include <sys/thread2.h>
e3161323 68#include <sys/sysref2.h>
654a39f0 69
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70static int procfs_rwmem (struct proc *curp,
71 struct proc *p, struct uio *uio);
984263bc 72
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73/*
74 * p->p_token must be held.
75 */
984263bc 76static int
ac424f9b 77procfs_rwmem(struct proc *curp, struct proc *p, struct uio *uio)
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78{
79 int error;
80 int writing;
81 struct vmspace *vm;
82 vm_map_t map;
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83 vm_offset_t pageno = 0; /* page number */
84 vm_prot_t reqprot;
85 vm_offset_t kva;
86
87 /*
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88 * if the vmspace is in the midst of being allocated or deallocated,
89 * or the process is exiting, don't try to grab anything. The
90 * page table usage in that process may be messed up.
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91 */
92 vm = p->p_vmspace;
4643740a 93 if ((p->p_flags & P_WEXIT) || sysref_isinactive(&vm->vm_sysref)) {
984263bc 94 return EFAULT;
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95 }
96
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97 /*
98 * The map we want...
99 */
100 map = &vm->vm_map;
101
102 writing = uio->uio_rw == UIO_WRITE;
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103 reqprot = VM_PROT_READ;
104 if (writing)
105 reqprot |= VM_PROT_WRITE | VM_PROT_OVERRIDE_WRITE;
984263bc 106
e4846942 107 kva = kmem_alloc_pageable(&kernel_map, PAGE_SIZE);
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108
109 /*
110 * Only map in one page at a time. We don't have to, but it
111 * makes things easier. This way is trivial - right?
112 */
113 do {
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114 vm_offset_t uva;
115 int page_offset; /* offset into page */
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116 u_int len;
117 vm_page_t m;
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118
119 uva = (vm_offset_t) uio->uio_offset;
120
121 /*
122 * Get the page number of this segment.
123 */
124 pageno = trunc_page(uva);
125 page_offset = uva - pageno;
126
127 /*
128 * How many bytes to copy
129 */
e54488bb 130 len = szmin(PAGE_SIZE - page_offset, uio->uio_resid);
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131
132 /*
133 * Fault the page on behalf of the process
134 */
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135 m = vm_fault_page(map, pageno, reqprot,
136 VM_FAULT_NORMAL, &error);
984263bc 137 if (error) {
4e158347 138 KKASSERT(m == NULL);
06ecca5a 139 error = EFAULT;
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140 break;
141 }
142
143 /*
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144 * Cleanup tmap then create a temporary KVA mapping and
145 * do the I/O.
984263bc 146 */
984263bc 147 pmap_kenter(kva, VM_PAGE_TO_PHYS(m));
984263bc 148 error = uiomove((caddr_t)(kva + page_offset), len, uio);
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149 pmap_kremove(kva);
150
151 /*
06ecca5a 152 * release the page and we are done
984263bc 153 */
b6f5e86b 154 vm_page_unhold(m);
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155 } while (error == 0 && uio->uio_resid > 0);
156
e4846942 157 kmem_free(&kernel_map, kva, PAGE_SIZE);
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158 return (error);
159}
160
161/*
162 * Copy data in and out of the target process.
163 * We do this by mapping the process's page into
164 * the kernel and then doing a uiomove direct
165 * from the kernel address space.
166 */
167int
c7e98b2f 168procfs_domem(struct proc *curp, struct lwp *lp, struct pfsnode *pfs,
ac424f9b 169 struct uio *uio)
984263bc 170{
c7e98b2f 171 struct proc *p = lp->lwp_proc;
b0c15cdf 172 int error;
c7e98b2f 173
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174 if (uio->uio_resid == 0)
175 return (0);
176
b0c15cdf 177 lwkt_gettoken(&p->p_token);
4643740a 178 if ((p->p_flags & P_INEXEC) != 0) {
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179 /*
180 * Can't trace a process that's currently exec'ing.
181 */
182 error = EAGAIN;
183 } else if (!CHECKIO(curp, p) || p_trespass(curp->p_ucred, p->p_ucred)) {
184 /*
185 * Can't trace processes outside our jail
186 */
187 error = EPERM;
188 } else {
189 error = procfs_rwmem(curp, p, uio);
190 }
191 lwkt_reltoken(&p->p_token);
192 return(error);
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193}
194
195/*
196 * Given process (p), find the vnode from which
197 * its text segment is being executed.
198 *
199 * It would be nice to grab this information from
200 * the VM system, however, there is no sure-fire
201 * way of doing that. Instead, fork(), exec() and
202 * wait() all maintain the p_textvp field in the
203 * process proc structure which contains a held
204 * reference to the exec'ed vnode.
205 *
206 * XXX - Currently, this is not not used, as the
207 * /proc/pid/file object exposes an information leak
208 * that shouldn't happen. Using a mount option would
209 * make it configurable on a per-system (or, at least,
210 * per-mount) basis; however, that's not really best.
211 * The best way to do it, I think, would be as an
212 * ioctl; this would restrict it to the uid running
213 * program, or root, which seems a reasonable compromise.
214 * However, the number of applications for this is
215 * minimal, if it can't be seen in the filesytem space,
216 * and doint it as an ioctl makes it somewhat less
217 * useful due to the, well, inelegance.
218 *
219 */
220struct vnode *
ac424f9b 221procfs_findtextvp(struct proc *p)
984263bc 222{
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223 return (p->p_textvp);
224}