freebsd-dev/sys/miscfs/procfs/procfs_mem.c
John Dyson c6c4b08e59 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.
1996-07-02 01:40:52 +00:00

328 lines
8.2 KiB
C

/*
* Copyright (c) 1993 Jan-Simon Pendry
* Copyright (c) 1993 Sean Eric Fagan
* Copyright (c) 1993
* The Regents of the University of California. All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* Jan-Simon Pendry and Sean Eric Fagan.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* @(#)procfs_mem.c 8.4 (Berkeley) 1/21/94
*
* $Id: procfs_mem.c,v 1.18 1996/06/11 23:52:27 dyson Exp $
*/
/*
* This is a lightly hacked and merged version
* of sef's pread/pwrite functions
*/
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/time.h>
#include <sys/kernel.h>
#include <sys/proc.h>
#include <sys/vnode.h>
#include <miscfs/procfs/procfs.h>
#include <vm/vm.h>
#include <vm/vm_param.h>
#include <vm/vm_prot.h>
#include <vm/lock.h>
#include <vm/pmap.h>
#include <vm/vm_map.h>
#include <vm/vm_kern.h>
#include <vm/vm_object.h>
#include <vm/vm_page.h>
#include <vm/vm_extern.h>
#include <sys/user.h>
static int procfs_rwmem __P((struct proc *p, struct uio *uio));
static int
procfs_rwmem(p, uio)
struct proc *p;
struct uio *uio;
{
int error;
int writing;
struct vmspace *vm;
int fix_prot = 0;
vm_map_t map;
vm_object_t object = NULL;
vm_offset_t pageno = 0; /* page number */
/*
* if the vmspace is in the midst of being deallocated or the
* process is exiting, don't try to grab anything. The page table
* usage in that process can be messed up.
*/
vm = p->p_vmspace;
if ((p->p_flag & P_WEXIT) || (vm->vm_refcnt < 1))
return EFAULT;
++vm->vm_refcnt;
/*
* The map we want...
*/
map = &vm->vm_map;
writing = uio->uio_rw == UIO_WRITE;
/*
* Only map in one page at a time. We don't have to, but it
* makes things easier. This way is trivial - right?
*/
do {
vm_map_t tmap;
vm_offset_t kva = 0;
vm_offset_t uva;
int page_offset; /* offset into page */
vm_map_entry_t out_entry;
vm_prot_t out_prot;
boolean_t wired, single_use;
vm_pindex_t pindex;
u_int len;
fix_prot = 0;
object = NULL;
uva = (vm_offset_t) uio->uio_offset;
/*
* Get the page number of this segment.
*/
pageno = trunc_page(uva);
page_offset = uva - pageno;
/*
* How many bytes to copy
*/
len = min(PAGE_SIZE - page_offset, uio->uio_resid);
if (uva >= VM_MAXUSER_ADDRESS) {
if (writing || (uva >= (VM_MAXUSER_ADDRESS + UPAGES * PAGE_SIZE))) {
error = 0;
break;
}
/* we are reading the "U area", force it into core */
PHOLD(p);
/* sanity check */
if (!(p->p_flag & P_INMEM)) {
/* aiee! */
PRELE(p);
error = EFAULT;
break;
}
/* populate the ptrace/procfs area */
p->p_addr->u_kproc.kp_proc = *p;
fill_eproc (p, &p->p_addr->u_kproc.kp_eproc);
/* locate the in-core address */
kva = (u_int)p->p_addr + uva - VM_MAXUSER_ADDRESS;
/* transfer it */
error = uiomove((caddr_t)kva, len, uio);
/* let the pages go */
PRELE(p);
continue;
}
/*
* Check the permissions for the area we're interested
* in.
*/
if (writing) {
fix_prot = !vm_map_check_protection(map, pageno,
pageno + PAGE_SIZE, VM_PROT_WRITE);
if (fix_prot) {
/*
* If the page is not writable, we make it so.
* XXX It is possible that a page may *not* be
* read/executable, if a process changes that!
* We will assume, for now, that a page is either
* VM_PROT_ALL, or VM_PROT_READ|VM_PROT_EXECUTE.
*/
error = vm_map_protect(map, pageno,
pageno + PAGE_SIZE, VM_PROT_ALL, 0);
if (error) {
/*
* We don't have to undo something
* that didn't work, so we clear the
* flag.
*/
fix_prot = 0;
break;
}
}
}
/*
* Now we need to get the page. out_entry, out_prot, wired,
* and single_use aren't used. One would think the vm code
* would be a *bit* nicer... We use tmap because
* vm_map_lookup() can change the map argument.
*/
tmap = map;
error = vm_map_lookup(&tmap, pageno,
writing ? VM_PROT_WRITE : VM_PROT_READ,
&out_entry, &object, &pindex, &out_prot,
&wired, &single_use);
if (error) {
/*
* Make sure that there is no residue in 'object' from
* an error return on vm_map_lookup.
*/
object = NULL;
break;
}
/*
* We're done with tmap now.
* But reference the object first, so that we won't loose
* it.
*/
vm_object_reference(object);
vm_map_lookup_done(tmap, out_entry);
/*
* Fault the page in...
*/
if (writing && object->backing_object) {
vm_page_t m;
m = vm_page_lookup(object, pindex);
if (m == 0) {
error = vm_fault(map, pageno,
VM_PROT_WRITE, FALSE);
break;
}
}
/* Find space in kernel_map for the page we're interested in */
error = vm_map_find(kernel_map, object,
IDX_TO_OFF(pindex), &kva, PAGE_SIZE, 1,
VM_PROT_ALL, VM_PROT_ALL, 0);
if (error) {
break;
}
/*
* Mark the page we just found as pageable.
*/
error = vm_map_pageable(kernel_map, kva,
kva + PAGE_SIZE, 0);
if (error) {
vm_map_remove(kernel_map, kva, kva + PAGE_SIZE);
object = NULL;
break;
}
/*
* Now do the i/o move.
*/
error = uiomove((caddr_t)(kva + page_offset),
len, uio);
/*
* vm_map_remove gets rid of the object reference, so
* we need to get rid of our 'object' pointer if there
* is subsequently an error.
*/
vm_map_remove(kernel_map, kva, kva + PAGE_SIZE);
object = NULL;
/*
* Undo the protection 'damage'.
*/
if (fix_prot) {
vm_map_protect(map, pageno, pageno + PAGE_SIZE,
VM_PROT_READ|VM_PROT_EXECUTE, 0);
fix_prot = 0;
}
} while (error == 0 && uio->uio_resid > 0);
if (object)
vm_object_deallocate(object);
if (fix_prot)
vm_map_protect(map, pageno, pageno + PAGE_SIZE,
VM_PROT_READ|VM_PROT_EXECUTE, 0);
vmspace_free(vm);
return (error);
}
/*
* Copy data in and out of the target process.
* We do this by mapping the process's page into
* the kernel and then doing a uiomove direct
* from the kernel address space.
*/
int
procfs_domem(curp, p, pfs, uio)
struct proc *curp;
struct proc *p;
struct pfsnode *pfs;
struct uio *uio;
{
int error;
if (uio->uio_resid == 0)
return (0);
error = procfs_rwmem(p, uio);
return (error);
}
/*
* Given process (p), find the vnode from which
* it's text segment is being executed.
*
* It would be nice to grab this information from
* the VM system, however, there is no sure-fire
* way of doing that. Instead, fork(), exec() and
* wait() all maintain the p_textvp field in the
* process proc structure which contains a held
* reference to the exec'ed vnode.
*/
struct vnode *
procfs_findtextvp(p)
struct proc *p;
{
return (p->p_textvp);
}