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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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
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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 1.3 2003/06/23 17:55:44 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 <miscfs/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 static int procfs_rwmem __P((struct proc *curp,
67 struct proc *p, struct uio *uio));
70 procfs_rwmem(curp, p, uio)
79 vm_object_t object = NULL;
80 vm_offset_t pageno = 0; /* page number */
85 * if the vmspace is in the midst of being deallocated or the
86 * process is exiting, don't try to grab anything. The page table
87 * usage in that process can be messed up.
90 if ((p->p_flag & P_WEXIT) || (vm->vm_refcnt < 1))
98 writing = uio->uio_rw == UIO_WRITE;
99 reqprot = writing ? (VM_PROT_WRITE | VM_PROT_OVERRIDE_WRITE) : VM_PROT_READ;
101 kva = kmem_alloc_pageable(kernel_map, PAGE_SIZE);
104 * Only map in one page at a time. We don't have to, but it
105 * makes things easier. This way is trivial - right?
110 int page_offset; /* offset into page */
111 vm_map_entry_t out_entry;
120 uva = (vm_offset_t) uio->uio_offset;
123 * Get the page number of this segment.
125 pageno = trunc_page(uva);
126 page_offset = uva - pageno;
129 * How many bytes to copy
131 len = min(PAGE_SIZE - page_offset, uio->uio_resid);
134 * Fault the page on behalf of the process
136 error = vm_fault(map, pageno, reqprot, VM_FAULT_NORMAL);
143 * Now we need to get the page. out_entry, out_prot, wired,
144 * and single_use aren't used. One would think the vm code
145 * would be a *bit* nicer... We use tmap because
146 * vm_map_lookup() can change the map argument.
149 error = vm_map_lookup(&tmap, pageno, reqprot,
150 &out_entry, &object, &pindex, &out_prot,
157 * Make sure that there is no residue in 'object' from
158 * an error return on vm_map_lookup.
165 m = vm_page_lookup(object, pindex);
167 /* Allow fallback to backing objects if we are reading */
169 while (m == NULL && !writing && object->backing_object) {
171 pindex += OFF_TO_IDX(object->backing_object_offset);
172 object = object->backing_object;
174 m = vm_page_lookup(object, pindex);
181 * Make sure that there is no residue in 'object' from
182 * an error return on vm_map_lookup.
186 vm_map_lookup_done(tmap, out_entry);
192 * Wire the page into memory
197 * We're done with tmap now.
198 * But reference the object first, so that we won't loose
201 vm_object_reference(object);
202 vm_map_lookup_done(tmap, out_entry);
204 pmap_kenter(kva, VM_PAGE_TO_PHYS(m));
207 * Now do the i/o move.
209 error = uiomove((caddr_t)(kva + page_offset), len, uio);
214 * release the page and the object
216 vm_page_unwire(m, 1);
217 vm_object_deallocate(object);
221 } while (error == 0 && uio->uio_resid > 0);
224 vm_object_deallocate(object);
226 kmem_free(kernel_map, kva, PAGE_SIZE);
232 * Copy data in and out of the target process.
233 * We do this by mapping the process's page into
234 * the kernel and then doing a uiomove direct
235 * from the kernel address space.
238 procfs_domem(curp, p, pfs, uio)
245 if (uio->uio_resid == 0)
248 /* Can't trace a process that's currently exec'ing. */
249 if ((p->p_flag & P_INEXEC) != 0)
251 if (!CHECKIO(curp, p) || p_trespass(curp->p_ucred, p->p_ucred))
254 return (procfs_rwmem(curp, p, uio));
258 * Given process (p), find the vnode from which
259 * its text segment is being executed.
261 * It would be nice to grab this information from
262 * the VM system, however, there is no sure-fire
263 * way of doing that. Instead, fork(), exec() and
264 * wait() all maintain the p_textvp field in the
265 * process proc structure which contains a held
266 * reference to the exec'ed vnode.
268 * XXX - Currently, this is not not used, as the
269 * /proc/pid/file object exposes an information leak
270 * that shouldn't happen. Using a mount option would
271 * make it configurable on a per-system (or, at least,
272 * per-mount) basis; however, that's not really best.
273 * The best way to do it, I think, would be as an
274 * ioctl; this would restrict it to the uid running
275 * program, or root, which seems a reasonable compromise.
276 * However, the number of applications for this is
277 * minimal, if it can't be seen in the filesytem space,
278 * and doint it as an ioctl makes it somewhat less
279 * useful due to the, well, inelegance.
287 return (p->p_textvp);