mirror of
https://git.FreeBSD.org/src.git
synced 2024-12-14 10:09:48 +00:00
Fix a serious problem, with a window where an object lock is needed,
but not there. The extent of the object lock is expanded to be over the range that it is needed. Additionally, clean up the code so that it conforms to better coding style.
This commit is contained in:
John Dyson
parent
73410b698a
commit
c6c4b08e59
Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=16889
@ -37,7 +37,7 @@
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*
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* @(#)procfs_mem.c 8.4 (Berkeley) 1/21/94
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*
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* $Id: procfs_mem.c,v 1.17 1996/01/25 06:05:38 peter Exp $
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* $Id: procfs_mem.c,v 1.18 1996/06/11 23:52:27 dyson Exp $
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*/
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/*
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@ -74,6 +74,10 @@ procfs_rwmem(p, uio)
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int error;
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int writing;
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struct vmspace *vm;
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int fix_prot = 0;
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vm_map_t map;
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vm_object_t object = NULL;
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vm_offset_t pageno = 0; /* page number */
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/*
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* if the vmspace is in the midst of being deallocated or the
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@ -84,6 +88,10 @@ procfs_rwmem(p, uio)
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if ((p->p_flag & P_WEXIT) || (vm->vm_refcnt < 1))
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return EFAULT;
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++vm->vm_refcnt;
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/*
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* The map we want...
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*/
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map = &vm->vm_map;
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writing = uio->uio_rw == UIO_WRITE;
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@ -92,19 +100,18 @@ procfs_rwmem(p, uio)
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* makes things easier. This way is trivial - right?
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*/
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do {
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vm_map_t map, tmap;
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vm_object_t object;
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vm_map_t tmap;
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vm_offset_t kva = 0;
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vm_offset_t uva;
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int page_offset; /* offset into page */
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vm_offset_t pageno; /* page number */
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vm_map_entry_t out_entry;
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vm_prot_t out_prot;
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vm_page_t m;
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boolean_t wired, single_use;
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vm_pindex_t pindex;
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u_int len;
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int fix_prot;
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fix_prot = 0;
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object = NULL;
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uva = (vm_offset_t) uio->uio_offset;
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@ -131,6 +138,7 @@ procfs_rwmem(p, uio)
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/* sanity check */
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if (!(p->p_flag & P_INMEM)) {
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/* aiee! */
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PRELE(p);
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error = EFAULT;
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break;
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}
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@ -151,33 +159,34 @@ procfs_rwmem(p, uio)
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continue;
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}
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/*
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* The map we want...
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*/
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map = &vm->vm_map;
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/*
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* Check the permissions for the area we're interested
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* in.
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*/
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fix_prot = 0;
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if (writing)
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if (writing) {
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fix_prot = !vm_map_check_protection(map, pageno,
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pageno + PAGE_SIZE, VM_PROT_WRITE);
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if (fix_prot) {
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/*
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* If the page is not writable, we make it so.
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* XXX It is possible that a page may *not* be
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* read/executable, if a process changes that!
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* We will assume, for now, that a page is either
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* VM_PROT_ALL, or VM_PROT_READ|VM_PROT_EXECUTE.
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*/
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error = vm_map_protect(map, pageno,
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if (fix_prot) {
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/*
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* If the page is not writable, we make it so.
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* XXX It is possible that a page may *not* be
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* read/executable, if a process changes that!
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* We will assume, for now, that a page is either
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* VM_PROT_ALL, or VM_PROT_READ|VM_PROT_EXECUTE.
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*/
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error = vm_map_protect(map, pageno,
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pageno + PAGE_SIZE, VM_PROT_ALL, 0);
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if (error)
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break;
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if (error) {
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/*
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* We don't have to undo something
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* that didn't work, so we clear the
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* flag.
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*/
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fix_prot = 0;
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break;
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}
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}
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}
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/*
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@ -188,59 +197,90 @@ procfs_rwmem(p, uio)
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*/
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tmap = map;
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error = vm_map_lookup(&tmap, pageno,
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writing ? VM_PROT_WRITE : VM_PROT_READ,
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&out_entry, &object, &pindex, &out_prot,
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&wired, &single_use);
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writing ? VM_PROT_WRITE : VM_PROT_READ,
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&out_entry, &object, &pindex, &out_prot,
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&wired, &single_use);
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if (error) {
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/*
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* Make sure that there is no residue in 'object' from
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* an error return on vm_map_lookup.
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*/
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object = NULL;
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break;
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}
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/*
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* We're done with tmap now.
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* But reference the object first, so that we won't loose
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* it.
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*/
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if (!error)
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vm_map_lookup_done(tmap, out_entry);
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vm_object_reference(object);
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vm_map_lookup_done(tmap, out_entry);
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/*
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* Fault the page in...
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*/
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if (!error && writing && object->backing_object) {
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if (writing && object->backing_object) {
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vm_page_t m;
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m = vm_page_lookup(object, pindex);
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if (m == 0)
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if (m == 0) {
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error = vm_fault(map, pageno,
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VM_PROT_WRITE, FALSE);
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VM_PROT_WRITE, FALSE);
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break;
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}
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}
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/* Find space in kernel_map for the page we're interested in */
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if (!error)
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error = vm_map_find(kernel_map, object,
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error = vm_map_find(kernel_map, object,
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IDX_TO_OFF(pindex), &kva, PAGE_SIZE, 1,
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VM_PROT_ALL, VM_PROT_ALL, 0);
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if (!error) {
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/*
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* Neither vm_map_lookup() nor vm_map_find() appear
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* to add a reference count to the object, so we do
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* that here and now.
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*/
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vm_object_reference(object);
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/*
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* Mark the page we just found as pageable.
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*/
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error = vm_map_pageable(kernel_map, kva,
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kva + PAGE_SIZE, 0);
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/*
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* Now do the i/o move.
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*/
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if (!error)
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error = uiomove((caddr_t)(kva + page_offset),
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len, uio);
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vm_map_remove(kernel_map, kva, kva + PAGE_SIZE);
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if (error) {
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break;
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}
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if (fix_prot)
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/*
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* Mark the page we just found as pageable.
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*/
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error = vm_map_pageable(kernel_map, kva,
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kva + PAGE_SIZE, 0);
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if (error) {
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vm_map_remove(kernel_map, kva, kva + PAGE_SIZE);
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object = NULL;
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break;
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}
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/*
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* Now do the i/o move.
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*/
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error = uiomove((caddr_t)(kva + page_offset),
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len, uio);
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/*
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* vm_map_remove gets rid of the object reference, so
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* we need to get rid of our 'object' pointer if there
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* is subsequently an error.
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*/
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vm_map_remove(kernel_map, kva, kva + PAGE_SIZE);
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object = NULL;
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/*
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* Undo the protection 'damage'.
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*/
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if (fix_prot) {
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vm_map_protect(map, pageno, pageno + PAGE_SIZE,
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VM_PROT_READ|VM_PROT_EXECUTE, 0);
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VM_PROT_READ|VM_PROT_EXECUTE, 0);
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fix_prot = 0;
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}
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} while (error == 0 && uio->uio_resid > 0);
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if (object)
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vm_object_deallocate(object);
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if (fix_prot)
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vm_map_protect(map, pageno, pageno + PAGE_SIZE,
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VM_PROT_READ|VM_PROT_EXECUTE, 0);
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vmspace_free(vm);
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return (error);
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}
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@ -37,7 +37,7 @@
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*
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* @(#)procfs_mem.c 8.4 (Berkeley) 1/21/94
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*
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* $Id: procfs_mem.c,v 1.17 1996/01/25 06:05:38 peter Exp $
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* $Id: procfs_mem.c,v 1.18 1996/06/11 23:52:27 dyson Exp $
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*/
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/*
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@ -74,6 +74,10 @@ procfs_rwmem(p, uio)
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int error;
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int writing;
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struct vmspace *vm;
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int fix_prot = 0;
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vm_map_t map;
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vm_object_t object = NULL;
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vm_offset_t pageno = 0; /* page number */
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/*
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* if the vmspace is in the midst of being deallocated or the
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@ -84,6 +88,10 @@ procfs_rwmem(p, uio)
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if ((p->p_flag & P_WEXIT) || (vm->vm_refcnt < 1))
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return EFAULT;
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++vm->vm_refcnt;
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/*
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* The map we want...
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*/
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map = &vm->vm_map;
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writing = uio->uio_rw == UIO_WRITE;
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@ -92,19 +100,18 @@ procfs_rwmem(p, uio)
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* makes things easier. This way is trivial - right?
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*/
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do {
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vm_map_t map, tmap;
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vm_object_t object;
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vm_map_t tmap;
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vm_offset_t kva = 0;
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vm_offset_t uva;
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int page_offset; /* offset into page */
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vm_offset_t pageno; /* page number */
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vm_map_entry_t out_entry;
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vm_prot_t out_prot;
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vm_page_t m;
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boolean_t wired, single_use;
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vm_pindex_t pindex;
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u_int len;
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int fix_prot;
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fix_prot = 0;
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object = NULL;
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uva = (vm_offset_t) uio->uio_offset;
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@ -131,6 +138,7 @@ procfs_rwmem(p, uio)
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/* sanity check */
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if (!(p->p_flag & P_INMEM)) {
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/* aiee! */
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PRELE(p);
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error = EFAULT;
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break;
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}
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@ -151,33 +159,34 @@ procfs_rwmem(p, uio)
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continue;
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}
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/*
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* The map we want...
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*/
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map = &vm->vm_map;
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/*
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* Check the permissions for the area we're interested
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* in.
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*/
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fix_prot = 0;
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if (writing)
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if (writing) {
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fix_prot = !vm_map_check_protection(map, pageno,
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pageno + PAGE_SIZE, VM_PROT_WRITE);
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if (fix_prot) {
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/*
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* If the page is not writable, we make it so.
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* XXX It is possible that a page may *not* be
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* read/executable, if a process changes that!
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* We will assume, for now, that a page is either
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* VM_PROT_ALL, or VM_PROT_READ|VM_PROT_EXECUTE.
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*/
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error = vm_map_protect(map, pageno,
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if (fix_prot) {
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/*
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* If the page is not writable, we make it so.
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* XXX It is possible that a page may *not* be
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* read/executable, if a process changes that!
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* We will assume, for now, that a page is either
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* VM_PROT_ALL, or VM_PROT_READ|VM_PROT_EXECUTE.
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*/
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error = vm_map_protect(map, pageno,
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pageno + PAGE_SIZE, VM_PROT_ALL, 0);
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if (error)
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break;
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if (error) {
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/*
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* We don't have to undo something
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* that didn't work, so we clear the
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* flag.
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*/
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fix_prot = 0;
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break;
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}
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}
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}
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/*
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@ -188,59 +197,90 @@ procfs_rwmem(p, uio)
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*/
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tmap = map;
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error = vm_map_lookup(&tmap, pageno,
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writing ? VM_PROT_WRITE : VM_PROT_READ,
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&out_entry, &object, &pindex, &out_prot,
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&wired, &single_use);
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writing ? VM_PROT_WRITE : VM_PROT_READ,
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&out_entry, &object, &pindex, &out_prot,
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&wired, &single_use);
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if (error) {
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/*
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* Make sure that there is no residue in 'object' from
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* an error return on vm_map_lookup.
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*/
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object = NULL;
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break;
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}
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/*
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* We're done with tmap now.
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* But reference the object first, so that we won't loose
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* it.
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*/
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if (!error)
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vm_map_lookup_done(tmap, out_entry);
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vm_object_reference(object);
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vm_map_lookup_done(tmap, out_entry);
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/*
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* Fault the page in...
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*/
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if (!error && writing && object->backing_object) {
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if (writing && object->backing_object) {
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vm_page_t m;
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m = vm_page_lookup(object, pindex);
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if (m == 0)
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if (m == 0) {
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error = vm_fault(map, pageno,
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VM_PROT_WRITE, FALSE);
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VM_PROT_WRITE, FALSE);
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break;
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}
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}
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/* Find space in kernel_map for the page we're interested in */
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if (!error)
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error = vm_map_find(kernel_map, object,
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error = vm_map_find(kernel_map, object,
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IDX_TO_OFF(pindex), &kva, PAGE_SIZE, 1,
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VM_PROT_ALL, VM_PROT_ALL, 0);
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if (!error) {
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/*
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* Neither vm_map_lookup() nor vm_map_find() appear
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* to add a reference count to the object, so we do
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* that here and now.
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*/
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vm_object_reference(object);
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/*
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* Mark the page we just found as pageable.
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*/
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error = vm_map_pageable(kernel_map, kva,
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kva + PAGE_SIZE, 0);
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/*
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* Now do the i/o move.
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*/
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if (!error)
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error = uiomove((caddr_t)(kva + page_offset),
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len, uio);
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vm_map_remove(kernel_map, kva, kva + PAGE_SIZE);
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if (error) {
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break;
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}
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if (fix_prot)
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/*
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* Mark the page we just found as pageable.
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*/
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error = vm_map_pageable(kernel_map, kva,
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kva + PAGE_SIZE, 0);
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if (error) {
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vm_map_remove(kernel_map, kva, kva + PAGE_SIZE);
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object = NULL;
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break;
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}
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/*
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* Now do the i/o move.
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*/
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error = uiomove((caddr_t)(kva + page_offset),
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len, uio);
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/*
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* vm_map_remove gets rid of the object reference, so
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* we need to get rid of our 'object' pointer if there
|
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* is subsequently an error.
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*/
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vm_map_remove(kernel_map, kva, kva + PAGE_SIZE);
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object = NULL;
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/*
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* Undo the protection 'damage'.
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*/
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if (fix_prot) {
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vm_map_protect(map, pageno, pageno + PAGE_SIZE,
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VM_PROT_READ|VM_PROT_EXECUTE, 0);
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VM_PROT_READ|VM_PROT_EXECUTE, 0);
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fix_prot = 0;
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}
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} while (error == 0 && uio->uio_resid > 0);
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if (object)
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vm_object_deallocate(object);
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if (fix_prot)
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vm_map_protect(map, pageno, pageno + PAGE_SIZE,
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VM_PROT_READ|VM_PROT_EXECUTE, 0);
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vmspace_free(vm);
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return (error);
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}
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