freebsd-nq/sys/fs/procfs/procfs_map.c
John Baldwin 2ff47c5f18 Remove unnecessary locking around vn_fullpath(). The vnode lock for the
vnode in question does not need to be held.  All the data structures used
during the name lookup are protected by the global name cache lock.
Instead, the caller merely needs to ensure a reference is held on the
vnode (such as vhold()) to keep it from being freed.

In the case of procfs' <pid>/file entry, grab the process lock while we
gain a new reference (via vhold()) on p_textvp to fully close races with
execve(2).

For the kern.proc.vmmap sysctl handler, use a shared vnode lock around
the call to VOP_GETATTR() rather than an exclusive lock.

MFC after:	1 month
2008-11-04 19:04:01 +00:00

222 lines
5.8 KiB
C

/*-
* Copyright (c) 1993 Jan-Simon Pendry
* 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.
*
* 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.
* 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_status.c 8.3 (Berkeley) 2/17/94
*
* $FreeBSD$
*/
#include "opt_compat.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/lock.h>
#include <sys/filedesc.h>
#include <sys/malloc.h>
#include <sys/mount.h>
#include <sys/mutex.h>
#include <sys/proc.h>
#include <sys/sbuf.h>
#include <sys/uio.h>
#include <sys/vnode.h>
#include <fs/pseudofs/pseudofs.h>
#include <fs/procfs/procfs.h>
#include <vm/vm.h>
#include <vm/pmap.h>
#include <vm/vm_map.h>
#include <vm/vm_page.h>
#include <vm/vm_object.h>
#ifdef COMPAT_IA32
#include <sys/procfs.h>
#include <machine/fpu.h>
#include <compat/ia32/ia32_reg.h>
extern struct sysentvec ia32_freebsd_sysvec;
#endif
#define MEBUFFERSIZE 256
/*
* The map entries can *almost* be read with programs like cat. However,
* large maps need special programs to read. It is not easy to implement
* a program that can sense the required size of the buffer, and then
* subsequently do a read with the appropriate size. This operation cannot
* be atomic. The best that we can do is to allow the program to do a read
* with an arbitrarily large buffer, and return as much as we can. We can
* return an error code if the buffer is too small (EFBIG), then the program
* can try a bigger buffer.
*/
int
procfs_doprocmap(PFS_FILL_ARGS)
{
int error, vfslocked;
vm_map_t map = &p->p_vmspace->vm_map;
vm_map_entry_t entry;
struct vnode *vp;
char *fullpath, *freepath;
#ifdef COMPAT_IA32
int wrap32 = 0;
#endif
PROC_LOCK(p);
error = p_candebug(td, p);
PROC_UNLOCK(p);
if (error)
return (error);
if (uio->uio_rw != UIO_READ)
return (EOPNOTSUPP);
#ifdef COMPAT_IA32
if (curthread->td_proc->p_sysent == &ia32_freebsd_sysvec) {
if (p->p_sysent != &ia32_freebsd_sysvec)
return (EOPNOTSUPP);
wrap32 = 1;
}
#endif
vm_map_lock_read(map);
for (entry = map->header.next; entry != &map->header;
entry = entry->next) {
vm_object_t obj, tobj, lobj;
int ref_count, shadow_count, flags;
vm_offset_t addr;
int resident, privateresident;
char *type;
if (entry->eflags & MAP_ENTRY_IS_SUB_MAP)
continue;
privateresident = 0;
obj = entry->object.vm_object;
if (obj != NULL) {
VM_OBJECT_LOCK(obj);
if (obj->shadow_count == 1)
privateresident = obj->resident_page_count;
}
resident = 0;
addr = entry->start;
while (addr < entry->end) {
if (pmap_extract(map->pmap, addr))
resident++;
addr += PAGE_SIZE;
}
for (lobj = tobj = obj; tobj; tobj = tobj->backing_object) {
if (tobj != obj)
VM_OBJECT_LOCK(tobj);
if (lobj != obj)
VM_OBJECT_UNLOCK(lobj);
lobj = tobj;
}
freepath = NULL;
fullpath = "-";
if (lobj) {
switch(lobj->type) {
default:
case OBJT_DEFAULT:
type = "default";
vp = NULL;
break;
case OBJT_VNODE:
type = "vnode";
vp = lobj->handle;
vref(vp);
break;
case OBJT_SWAP:
type = "swap";
vp = NULL;
break;
case OBJT_DEVICE:
type = "device";
vp = NULL;
break;
}
if (lobj != obj)
VM_OBJECT_UNLOCK(lobj);
flags = obj->flags;
ref_count = obj->ref_count;
shadow_count = obj->shadow_count;
VM_OBJECT_UNLOCK(obj);
if (vp != NULL) {
vn_fullpath(td, vp, &fullpath, &freepath);
vfslocked = VFS_LOCK_GIANT(vp->v_mount);
vrele(vp);
VFS_UNLOCK_GIANT(vfslocked);
}
} else {
type = "none";
flags = 0;
ref_count = 0;
shadow_count = 0;
}
/*
* format:
* start, end, resident, private resident, cow, access, type.
*/
error = sbuf_printf(sb,
"0x%lx 0x%lx %d %d %p %s%s%s %d %d 0x%x %s %s %s %s\n",
(u_long)entry->start, (u_long)entry->end,
resident, privateresident,
#ifdef COMPAT_IA32
wrap32 ? NULL : obj, /* Hide 64 bit value */
#else
obj,
#endif
(entry->protection & VM_PROT_READ)?"r":"-",
(entry->protection & VM_PROT_WRITE)?"w":"-",
(entry->protection & VM_PROT_EXECUTE)?"x":"-",
ref_count, shadow_count, flags,
(entry->eflags & MAP_ENTRY_COW)?"COW":"NCOW",
(entry->eflags & MAP_ENTRY_NEEDS_COPY)?"NC":"NNC",
type, fullpath);
if (freepath != NULL)
free(freepath, M_TEMP);
if (error == -1) {
error = 0;
break;
}
}
vm_map_unlock_read(map);
return (error);
}