NetBSD/sys/uvm/uvm_mremap.c

/*	$NetBSD: uvm_mremap.c,v 1.4 2007/02/21 23:00:14 thorpej Exp $	*/

/*-
 * Copyright (c)2006 YAMAMOTO Takashi,
 * All rights reserved.
 *
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: uvm_mremap.c,v 1.4 2007/02/21 23:00:14 thorpej Exp $");

#include <sys/param.h>

#include <uvm/uvm.h>

static int
uvm_mapent_extend(struct vm_map *map, vaddr_t endva, vsize_t size)
{
	struct vm_map_entry *entry;
	struct vm_map_entry *reserved_entry;
	struct uvm_object *uobj;
	int error = 0;

	vm_map_lock(map);
	if (!uvm_map_lookup_entry(map, endva, &reserved_entry)) {
		error = ENOENT;
		goto done;
	}
	if (reserved_entry->start != endva ||
	    reserved_entry->end != endva + size ||
	    reserved_entry->object.uvm_obj != NULL ||
	    reserved_entry->aref.ar_amap != NULL) {
		error = EINVAL;
		goto done;
	}
	entry = reserved_entry->prev;
	KASSERT(&map->header != entry);
	if (entry->end != endva) {
		error = EINVAL;
		goto done;
	}

	/*
	 * now, make reserved_entry compatible with entry, and then
	 * try to merge.
	 */

	uobj = entry->object.uvm_obj;
	if (uobj) {
		voff_t offset = entry->offset;
		voff_t newoffset;
		
		newoffset = offset + entry->end - entry->start;
		if (newoffset <= offset) {
			error = E2BIG; /* XXX */
			goto done;
		}
		simple_lock(&uobj->vmobjlock);
		KASSERT(uobj->uo_refs > 0);
		uobj->uo_refs++;
		simple_unlock(&uobj->vmobjlock);
		reserved_entry->object.uvm_obj = uobj;
		reserved_entry->offset = newoffset;
	}
	reserved_entry->etype = entry->etype;
	if (UVM_ET_ISCOPYONWRITE(entry)) {
		reserved_entry->etype |= UVM_ET_NEEDSCOPY;
	}
	reserved_entry->flags &= ~UVM_MAP_NOMERGE;
	reserved_entry->protection = entry->protection;
	reserved_entry->max_protection = entry->max_protection;
	reserved_entry->inheritance = entry->inheritance;
	reserved_entry->advice = entry->advice;
	reserved_entry->wired_count = 0; /* XXX should inherit? */
	uvm_mapent_trymerge(map, reserved_entry, 0);
done:
	vm_map_unlock(map);

	return error;
}

/*
 * uvm_mremap: move and/or resize existing mappings.
 */

int
uvm_mremap(struct vm_map *oldmap, vaddr_t oldva, vsize_t oldsize,
    struct vm_map *newmap, vaddr_t *newvap, vsize_t newsize,
    struct proc *newproc, int flags)
{
	vaddr_t dstva;
	vsize_t movesize;
	vaddr_t newva;
	int error = 0;
	const bool fixed = (flags & UVM_MREMAP_FIXED) != 0;

	if (fixed) {
		newva = *newvap;
	} else {
		newva = 0;
	}
	if ((oldva & PAGE_MASK) != 0 ||
	    (newva & PAGE_MASK) != 0 ||
	    (oldsize & PAGE_MASK) != 0 ||
	    (newsize & PAGE_MASK) != 0) {
		return EINVAL;
	}
	/* XXX zero-size should be allowed? */
	if (oldva + oldsize <= oldva || newva + newsize <= newva) {
		return EINVAL;
	}

	/*
	 * check the easy cases first.
	 */

	if ((!fixed || newva == oldva) && newmap == oldmap) {
		vaddr_t va;

		if (newsize == oldsize) {
			newva = oldva;
			goto done;
		}
		if (newsize < oldsize) {
			uvm_unmap(oldmap, oldva + newsize, oldva + oldsize);
			newva = oldva;
			goto done;
		}
		va = oldva + oldsize;
		if (uvm_map_reserve(oldmap, newsize - oldsize, 0, 0, &va,
		    UVM_FLAG_FIXED)) {
			newva = oldva;
			goto extend;
		}
		if (fixed) {
			return ENOMEM;
		}
	}

	/*
	 * we need to move mappings.
	 */

	if (!fixed) {
		KASSERT(&newproc->p_vmspace->vm_map == newmap);
		newva = newproc->p_emul->e_vm_default_addr(newproc,
		    (vaddr_t)newproc->p_vmspace->vm_daddr, newsize);
	}
	dstva = newva;
	if (!uvm_map_reserve(newmap, newsize, oldva, 0, &dstva, 
	    fixed ? UVM_FLAG_FIXED : 0)) {
		return ENOMEM;
	}
	KASSERT(!fixed || dstva == newva);
	newva = dstva;
	movesize = MIN(oldsize, newsize);
	error = uvm_map_extract(oldmap, oldva, movesize, newmap, &dstva,
	    UVM_EXTRACT_RESERVED);
	KASSERT(dstva == newva);
	if (error != 0) {
		/* undo uvm_map_reserve */
		uvm_unmap(newmap, newva, newva + newsize);
		return error;
	}
	if (newsize > oldsize) {
extend:
		error = uvm_mapent_extend(newmap, newva + oldsize,
		    newsize - oldsize);
		if (error != 0) {
			/* undo uvm_map_reserve and uvm_map_extract */
			uvm_unmap(newmap, newva, newva + newsize);
			return error;
		}
	}

	/*
	 * now we won't fail.  remove original entries.
	 */

	if (oldva != newva || oldmap != newmap) {
		uvm_unmap(oldmap, oldva, oldva + oldsize);
	}
done:
	*newvap = newva;
	return 0;
}