2 * Copyright (c) 1993 Jan-Simon Pendry
3 * Copyright (c) 1993 Sean Eric Fagan
5 * The Regents of the University of California. All rights reserved.
7 * This code is derived from software contributed to Berkeley by
8 * Jan-Simon Pendry and Sean Eric Fagan.
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11 * modification, are permitted provided that the following conditions
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19 * must display the following acknowledgement:
20 * This product includes software developed by the University of
21 * California, Berkeley and its contributors.
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23 * may be used to endorse or promote products derived from this software
24 * without specific prior written permission.
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38 * @(#)procfs_mem.c 8.5 (Berkeley) 6/15/94
40 * $FreeBSD: src/sys/miscfs/procfs/procfs_mem.c,v 1.46.2.3 2002/01/22 17:22:59 nectar Exp $
41 * $DragonFly: src/sys/vfs/procfs/procfs_mem.c,v 1.11 2004/10/12 19:29:31 dillon Exp $
45 * This is a lightly hacked and merged version
46 * of sef's pread/pwrite functions
49 #include <sys/param.h>
50 #include <sys/systm.h>
52 #include <sys/vnode.h>
53 #include <vfs/procfs/procfs.h>
55 #include <vm/vm_param.h>
58 #include <vm/vm_extern.h>
59 #include <vm/vm_map.h>
60 #include <vm/vm_kern.h>
61 #include <vm/vm_object.h>
62 #include <vm/vm_page.h>
64 #include <sys/ptrace.h>
66 #include <sys/thread2.h>
68 static int procfs_rwmem (struct proc *curp,
69 struct proc *p, struct uio *uio);
72 procfs_rwmem(struct proc *curp, struct proc *p, struct uio *uio)
78 vm_offset_t pageno = 0; /* page number */
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.
88 if ((p->p_flag & P_WEXIT) || (vm->vm_refcnt < 1))
96 writing = uio->uio_rw == UIO_WRITE;
97 reqprot = writing ? (VM_PROT_WRITE | VM_PROT_OVERRIDE_WRITE) : VM_PROT_READ;
99 kva = kmem_alloc_pageable(kernel_map, PAGE_SIZE);
102 * Only map in one page at a time. We don't have to, but it
103 * makes things easier. This way is trivial - right?
108 int page_offset; /* offset into page */
109 vm_map_entry_t out_entry;
118 uva = (vm_offset_t) uio->uio_offset;
121 * Get the page number of this segment.
123 pageno = trunc_page(uva);
124 page_offset = uva - pageno;
127 * How many bytes to copy
129 len = min(PAGE_SIZE - page_offset, uio->uio_resid);
132 * Fault the page on behalf of the process
134 error = vm_fault(map, pageno, reqprot, VM_FAULT_NORMAL);
141 * Now we need to get the page. out_entry, out_prot, wired,
142 * and single_use aren't used. One would think the vm code
143 * would be a *bit* nicer... We use tmap because
144 * vm_map_lookup() can change the map argument.
147 error = vm_map_lookup(&tmap, pageno, reqprot,
148 &out_entry, &object, &pindex, &out_prot,
157 * spl protection is required to avoid interrupt freeing
158 * races, reference the object to avoid it being ripped
159 * out from under us if we block.
162 vm_object_reference(object);
164 m = vm_page_lookup(object, pindex);
167 * Allow fallback to backing objects if we are reading
169 while (m == NULL && !writing && object->backing_object) {
170 pindex += OFF_TO_IDX(object->backing_object_offset);
171 nobject = object->backing_object;
172 vm_object_reference(nobject);
173 vm_object_deallocate(object);
175 m = vm_page_lookup(object, pindex);
179 * Wait for any I/O's to complete, then hold the page
180 * so we can release the spl.
183 if (vm_page_sleep_busy(m, FALSE, "rwmem"))
190 * We no longer need the object. If we do not have a page
193 vm_object_deallocate(object);
195 vm_map_lookup_done(tmap, out_entry, 0);
201 * Cleanup tmap then create a temporary KVA mapping and
204 vm_map_lookup_done(tmap, out_entry, 0);
205 pmap_kenter(kva, VM_PAGE_TO_PHYS(m));
206 error = uiomove((caddr_t)(kva + page_offset), len, uio);
210 * release the page and we are done
215 } while (error == 0 && uio->uio_resid > 0);
217 kmem_free(kernel_map, kva, PAGE_SIZE);
223 * Copy data in and out of the target process.
224 * We do this by mapping the process's page into
225 * the kernel and then doing a uiomove direct
226 * from the kernel address space.
229 procfs_domem(struct proc *curp, struct proc *p, struct pfsnode *pfs,
232 if (uio->uio_resid == 0)
235 /* Can't trace a process that's currently exec'ing. */
236 if ((p->p_flag & P_INEXEC) != 0)
238 if (!CHECKIO(curp, p) || p_trespass(curp->p_ucred, p->p_ucred))
241 return (procfs_rwmem(curp, p, uio));
245 * Given process (p), find the vnode from which
246 * its text segment is being executed.
248 * It would be nice to grab this information from
249 * the VM system, however, there is no sure-fire
250 * way of doing that. Instead, fork(), exec() and
251 * wait() all maintain the p_textvp field in the
252 * process proc structure which contains a held
253 * reference to the exec'ed vnode.
255 * XXX - Currently, this is not not used, as the
256 * /proc/pid/file object exposes an information leak
257 * that shouldn't happen. Using a mount option would
258 * make it configurable on a per-system (or, at least,
259 * per-mount) basis; however, that's not really best.
260 * The best way to do it, I think, would be as an
261 * ioctl; this would restrict it to the uid running
262 * program, or root, which seems a reasonable compromise.
263 * However, the number of applications for this is
264 * minimal, if it can't be seen in the filesytem space,
265 * and doint it as an ioctl makes it somewhat less
266 * useful due to the, well, inelegance.
270 procfs_findtextvp(struct proc *p)
272 return (p->p_textvp);