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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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 $
44 * This is a lightly hacked and merged version
45 * of sef's pread/pwrite functions
48 #include <sys/param.h>
49 #include <sys/systm.h>
51 #include <sys/vnode.h>
52 #include <miscfs/procfs/procfs.h>
54 #include <vm/vm_param.h>
57 #include <vm/vm_extern.h>
58 #include <vm/vm_map.h>
59 #include <vm/vm_kern.h>
60 #include <vm/vm_object.h>
61 #include <vm/vm_page.h>
63 #include <sys/ptrace.h>
65 static int procfs_rwmem __P((struct proc *curp,
66 struct proc *p, struct uio *uio));
69 procfs_rwmem(curp, p, uio)
78 vm_object_t object = NULL;
79 vm_offset_t pageno = 0; /* page number */
84 * if the vmspace is in the midst of being deallocated or the
85 * process is exiting, don't try to grab anything. The page table
86 * usage in that process can be messed up.
89 if ((p->p_flag & P_WEXIT) || (vm->vm_refcnt < 1))
97 writing = uio->uio_rw == UIO_WRITE;
98 reqprot = writing ? (VM_PROT_WRITE | VM_PROT_OVERRIDE_WRITE) : VM_PROT_READ;
100 kva = kmem_alloc_pageable(kernel_map, PAGE_SIZE);
103 * Only map in one page at a time. We don't have to, but it
104 * makes things easier. This way is trivial - right?
109 int page_offset; /* offset into page */
110 vm_map_entry_t out_entry;
119 uva = (vm_offset_t) uio->uio_offset;
122 * Get the page number of this segment.
124 pageno = trunc_page(uva);
125 page_offset = uva - pageno;
128 * How many bytes to copy
130 len = min(PAGE_SIZE - page_offset, uio->uio_resid);
133 * Fault the page on behalf of the process
135 error = vm_fault(map, pageno, reqprot, VM_FAULT_NORMAL);
142 * Now we need to get the page. out_entry, out_prot, wired,
143 * and single_use aren't used. One would think the vm code
144 * would be a *bit* nicer... We use tmap because
145 * vm_map_lookup() can change the map argument.
148 error = vm_map_lookup(&tmap, pageno, reqprot,
149 &out_entry, &object, &pindex, &out_prot,
156 * Make sure that there is no residue in 'object' from
157 * an error return on vm_map_lookup.
164 m = vm_page_lookup(object, pindex);
166 /* Allow fallback to backing objects if we are reading */
168 while (m == NULL && !writing && object->backing_object) {
170 pindex += OFF_TO_IDX(object->backing_object_offset);
171 object = object->backing_object;
173 m = vm_page_lookup(object, pindex);
180 * Make sure that there is no residue in 'object' from
181 * an error return on vm_map_lookup.
185 vm_map_lookup_done(tmap, out_entry);
191 * Wire the page into memory
196 * We're done with tmap now.
197 * But reference the object first, so that we won't loose
200 vm_object_reference(object);
201 vm_map_lookup_done(tmap, out_entry);
203 pmap_kenter(kva, VM_PAGE_TO_PHYS(m));
206 * Now do the i/o move.
208 error = uiomove((caddr_t)(kva + page_offset), len, uio);
213 * release the page and the object
215 vm_page_unwire(m, 1);
216 vm_object_deallocate(object);
220 } while (error == 0 && uio->uio_resid > 0);
223 vm_object_deallocate(object);
225 kmem_free(kernel_map, kva, PAGE_SIZE);
231 * Copy data in and out of the target process.
232 * We do this by mapping the process's page into
233 * the kernel and then doing a uiomove direct
234 * from the kernel address space.
237 procfs_domem(curp, p, pfs, uio)
244 if (uio->uio_resid == 0)
247 /* Can't trace a process that's currently exec'ing. */
248 if ((p->p_flag & P_INEXEC) != 0)
250 if (!CHECKIO(curp, p) || p_trespass(curp, p))
253 return (procfs_rwmem(curp, p, uio));
257 * Given process (p), find the vnode from which
258 * its text segment is being executed.
260 * It would be nice to grab this information from
261 * the VM system, however, there is no sure-fire
262 * way of doing that. Instead, fork(), exec() and
263 * wait() all maintain the p_textvp field in the
264 * process proc structure which contains a held
265 * reference to the exec'ed vnode.
267 * XXX - Currently, this is not not used, as the
268 * /proc/pid/file object exposes an information leak
269 * that shouldn't happen. Using a mount option would
270 * make it configurable on a per-system (or, at least,
271 * per-mount) basis; however, that's not really best.
272 * The best way to do it, I think, would be as an
273 * ioctl; this would restrict it to the uid running
274 * program, or root, which seems a reasonable compromise.
275 * However, the number of applications for this is
276 * minimal, if it can't be seen in the filesytem space,
277 * and doint it as an ioctl makes it somewhat less
278 * useful due to the, well, inelegance.
286 return (p->p_textvp);