BSD 4.4 Lite Kernel Sources

1 files changed, 450 insertions, 0 deletions

diff --git a/sys/vm/vm_kern.c b/sys/vm/vm_kern.c
new file mode 100644
index 0000000..7e4db63
--- /dev/null
+++ b/sys/vm/vm_kern.c
@@ -0,0 +1,450 @@
+/* 
+ * Copyright (c) 1991, 1993
+ *	The Regents of the University of California.  All rights reserved.
+ *
+ * This code is derived from software contributed to Berkeley by
+ * The Mach Operating System project at Carnegie-Mellon University.
+ *
+ * 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.
+ *
+ *	@(#)vm_kern.c	8.3 (Berkeley) 1/12/94
+ *
+ *
+ * Copyright (c) 1987, 1990 Carnegie-Mellon University.
+ * All rights reserved.
+ *
+ * Authors: Avadis Tevanian, Jr., Michael Wayne Young
+ * 
+ * Permission to use, copy, modify and distribute this software and
+ * its documentation is hereby granted, provided that both the copyright
+ * notice and this permission notice appear in all copies of the
+ * software, derivative works or modified versions, and any portions
+ * thereof, and that both notices appear in supporting documentation.
+ * 
+ * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS" 
+ * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND 
+ * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
+ * 
+ * Carnegie Mellon requests users of this software to return to
+ *
+ *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
+ *  School of Computer Science
+ *  Carnegie Mellon University
+ *  Pittsburgh PA 15213-3890
+ *
+ * any improvements or extensions that they make and grant Carnegie the
+ * rights to redistribute these changes.
+ */
+
+/*
+ *	Kernel memory management.
+ */
+
+#include <sys/param.h>
+#include <sys/systm.h>
+
+#include <vm/vm.h>
+#include <vm/vm_page.h>
+#include <vm/vm_pageout.h>
+#include <vm/vm_kern.h>
+
+/*
+ *	kmem_alloc_pageable:
+ *
+ *	Allocate pageable memory to the kernel's address map.
+ *	map must be "kernel_map" below.
+ */
+
+vm_offset_t kmem_alloc_pageable(map, size)
+	vm_map_t		map;
+	register vm_size_t	size;
+{
+	vm_offset_t		addr;
+	register int		result;
+
+#if	0
+	if (map != kernel_map)
+		panic("kmem_alloc_pageable: not called with kernel_map");
+#endif
+
+	size = round_page(size);
+
+	addr = vm_map_min(map);
+	result = vm_map_find(map, NULL, (vm_offset_t) 0,
+				&addr, size, TRUE);
+	if (result != KERN_SUCCESS) {
+		return(0);
+	}
+
+	return(addr);
+}
+
+/*
+ *	Allocate wired-down memory in the kernel's address map
+ *	or a submap.
+ */
+vm_offset_t kmem_alloc(map, size)
+	register vm_map_t	map;
+	register vm_size_t	size;
+{
+	vm_offset_t		addr;
+	register vm_offset_t	offset;
+	extern vm_object_t	kernel_object;
+	vm_offset_t		i;
+
+	size = round_page(size);
+
+	/*
+	 *	Use the kernel object for wired-down kernel pages.
+	 *	Assume that no region of the kernel object is
+	 *	referenced more than once.
+	 */
+
+	/*
+	 * Locate sufficient space in the map.  This will give us the
+	 * final virtual address for the new memory, and thus will tell
+	 * us the offset within the kernel map.
+	 */
+	vm_map_lock(map);
+	if (vm_map_findspace(map, 0, size, &addr)) {
+		vm_map_unlock(map);
+		return (0);
+	}
+	offset = addr - VM_MIN_KERNEL_ADDRESS;
+	vm_object_reference(kernel_object);
+	vm_map_insert(map, kernel_object, offset, addr, addr + size);
+	vm_map_unlock(map);
+
+	/*
+	 *	Guarantee that there are pages already in this object
+	 *	before calling vm_map_pageable.  This is to prevent the
+	 *	following scenario:
+	 *
+	 *		1) Threads have swapped out, so that there is a
+	 *		   pager for the kernel_object.
+	 *		2) The kmsg zone is empty, and so we are kmem_allocing
+	 *		   a new page for it.
+	 *		3) vm_map_pageable calls vm_fault; there is no page,
+	 *		   but there is a pager, so we call
+	 *		   pager_data_request.  But the kmsg zone is empty,
+	 *		   so we must kmem_alloc.
+	 *		4) goto 1
+	 *		5) Even if the kmsg zone is not empty: when we get
+	 *		   the data back from the pager, it will be (very
+	 *		   stale) non-zero data.  kmem_alloc is defined to
+	 *		   return zero-filled memory.
+	 *
+	 *	We're intentionally not activating the pages we allocate
+	 *	to prevent a race with page-out.  vm_map_pageable will wire
+	 *	the pages.
+	 */
+
+	vm_object_lock(kernel_object);
+	for (i = 0 ; i < size; i+= PAGE_SIZE) {
+		vm_page_t	mem;
+
+		while ((mem = vm_page_alloc(kernel_object, offset+i)) == NULL) {
+			vm_object_unlock(kernel_object);
+			VM_WAIT;
+			vm_object_lock(kernel_object);
+		}
+		vm_page_zero_fill(mem);
+		mem->flags &= ~PG_BUSY;
+	}
+	vm_object_unlock(kernel_object);
+		
+	/*
+	 *	And finally, mark the data as non-pageable.
+	 */
+
+	(void) vm_map_pageable(map, (vm_offset_t) addr, addr + size, FALSE);
+
+	/*
+	 *	Try to coalesce the map
+	 */
+
+	vm_map_simplify(map, addr);
+
+	return(addr);
+}
+
+/*
+ *	kmem_free:
+ *
+ *	Release a region of kernel virtual memory allocated
+ *	with kmem_alloc, and return the physical pages
+ *	associated with that region.
+ */
+void kmem_free(map, addr, size)
+	vm_map_t		map;
+	register vm_offset_t	addr;
+	vm_size_t		size;
+{
+	(void) vm_map_remove(map, trunc_page(addr), round_page(addr + size));
+}
+
+/*
+ *	kmem_suballoc:
+ *
+ *	Allocates a map to manage a subrange
+ *	of the kernel virtual address space.
+ *
+ *	Arguments are as follows:
+ *
+ *	parent		Map to take range from
+ *	size		Size of range to find
+ *	min, max	Returned endpoints of map
+ *	pageable	Can the region be paged
+ */
+vm_map_t kmem_suballoc(parent, min, max, size, pageable)
+	register vm_map_t	parent;
+	vm_offset_t		*min, *max;
+	register vm_size_t	size;
+	boolean_t		pageable;
+{
+	register int	ret;
+	vm_map_t	result;
+
+	size = round_page(size);
+
+	*min = (vm_offset_t) vm_map_min(parent);
+	ret = vm_map_find(parent, NULL, (vm_offset_t) 0,
+				min, size, TRUE);
+	if (ret != KERN_SUCCESS) {
+		printf("kmem_suballoc: bad status return of %d.\n", ret);
+		panic("kmem_suballoc");
+	}
+	*max = *min + size;
+	pmap_reference(vm_map_pmap(parent));
+	result = vm_map_create(vm_map_pmap(parent), *min, *max, pageable);
+	if (result == NULL)
+		panic("kmem_suballoc: cannot create submap");
+	if ((ret = vm_map_submap(parent, *min, *max, result)) != KERN_SUCCESS)
+		panic("kmem_suballoc: unable to change range to submap");
+	return(result);
+}
+
+/*
+ * Allocate wired-down memory in the kernel's address map for the higher
+ * level kernel memory allocator (kern/kern_malloc.c).  We cannot use
+ * kmem_alloc() because we may need to allocate memory at interrupt
+ * level where we cannot block (canwait == FALSE).
+ *
+ * This routine has its own private kernel submap (kmem_map) and object
+ * (kmem_object).  This, combined with the fact that only malloc uses
+ * this routine, ensures that we will never block in map or object waits.
+ *
+ * Note that this still only works in a uni-processor environment and
+ * when called at splhigh().
+ *
+ * We don't worry about expanding the map (adding entries) since entries
+ * for wired maps are statically allocated.
+ */
+vm_offset_t
+kmem_malloc(map, size, canwait)
+	register vm_map_t	map;
+	register vm_size_t	size;
+	boolean_t		canwait;
+{
+	register vm_offset_t	offset, i;
+	vm_map_entry_t		entry;
+	vm_offset_t		addr;
+	vm_page_t		m;
+	extern vm_object_t	kmem_object;
+
+	if (map != kmem_map && map != mb_map)
+		panic("kern_malloc_alloc: map != {kmem,mb}_map");
+
+	size = round_page(size);
+	addr = vm_map_min(map);
+
+	/*
+	 * Locate sufficient space in the map.  This will give us the
+	 * final virtual address for the new memory, and thus will tell
+	 * us the offset within the kernel map.
+	 */
+	vm_map_lock(map);
+	if (vm_map_findspace(map, 0, size, &addr)) {
+		vm_map_unlock(map);
+		if (canwait)		/* XXX  should wait */
+			panic("kmem_malloc: %s too small",
+			    map == kmem_map ? "kmem_map" : "mb_map");
+		return (0);
+	}
+	offset = addr - vm_map_min(kmem_map);
+	vm_object_reference(kmem_object);
+	vm_map_insert(map, kmem_object, offset, addr, addr + size);
+
+	/*
+	 * If we can wait, just mark the range as wired
+	 * (will fault pages as necessary).
+	 */
+	if (canwait) {
+		vm_map_unlock(map);
+		(void) vm_map_pageable(map, (vm_offset_t) addr, addr + size,
+				       FALSE);
+		vm_map_simplify(map, addr);
+		return(addr);
+	}
+
+	/*
+	 * If we cannot wait then we must allocate all memory up front,
+	 * pulling it off the active queue to prevent pageout.
+	 */
+	vm_object_lock(kmem_object);
+	for (i = 0; i < size; i += PAGE_SIZE) {
+		m = vm_page_alloc(kmem_object, offset + i);
+
+		/*
+		 * Ran out of space, free everything up and return.
+		 * Don't need to lock page queues here as we know
+		 * that the pages we got aren't on any queues.
+		 */
+		if (m == NULL) {
+			while (i != 0) {
+				i -= PAGE_SIZE;
+				m = vm_page_lookup(kmem_object, offset + i);
+				vm_page_free(m);
+			}
+			vm_object_unlock(kmem_object);
+			vm_map_delete(map, addr, addr + size);
+			vm_map_unlock(map);
+			return(0);
+		}
+#if 0
+		vm_page_zero_fill(m);
+#endif
+		m->flags &= ~PG_BUSY;
+	}
+	vm_object_unlock(kmem_object);
+
+	/*
+	 * Mark map entry as non-pageable.
+	 * Assert: vm_map_insert() will never be able to extend the previous
+	 * entry so there will be a new entry exactly corresponding to this
+	 * address range and it will have wired_count == 0.
+	 */
+	if (!vm_map_lookup_entry(map, addr, &entry) ||
+	    entry->start != addr || entry->end != addr + size ||
+	    entry->wired_count)
+		panic("kmem_malloc: entry not found or misaligned");
+	entry->wired_count++;
+
+	/*
+	 * Loop thru pages, entering them in the pmap.
+	 * (We cannot add them to the wired count without
+	 * wrapping the vm_page_queue_lock in splimp...)
+	 */
+	for (i = 0; i < size; i += PAGE_SIZE) {
+		vm_object_lock(kmem_object);
+		m = vm_page_lookup(kmem_object, offset + i);
+		vm_object_unlock(kmem_object);
+		pmap_enter(map->pmap, addr + i, VM_PAGE_TO_PHYS(m),
+			   VM_PROT_DEFAULT, TRUE);
+	}
+	vm_map_unlock(map);
+
+	vm_map_simplify(map, addr);
+	return(addr);
+}
+
+/*
+ *	kmem_alloc_wait
+ *
+ *	Allocates pageable memory from a sub-map of the kernel.  If the submap
+ *	has no room, the caller sleeps waiting for more memory in the submap.
+ *
+ */
+vm_offset_t kmem_alloc_wait(map, size)
+	vm_map_t	map;
+	vm_size_t	size;
+{
+	vm_offset_t	addr;
+
+	size = round_page(size);
+
+	for (;;) {
+		/*
+		 * To make this work for more than one map,
+		 * use the map's lock to lock out sleepers/wakers.
+		 */
+		vm_map_lock(map);
+		if (vm_map_findspace(map, 0, size, &addr) == 0)
+			break;
+		/* no space now; see if we can ever get space */
+		if (vm_map_max(map) - vm_map_min(map) < size) {
+			vm_map_unlock(map);
+			return (0);
+		}
+		assert_wait((int)map, TRUE);
+		vm_map_unlock(map);
+		thread_block();
+	}
+	vm_map_insert(map, NULL, (vm_offset_t)0, addr, addr + size);
+	vm_map_unlock(map);
+	return (addr);
+}
+
+/*
+ *	kmem_free_wakeup
+ *
+ *	Returns memory to a submap of the kernel, and wakes up any threads
+ *	waiting for memory in that map.
+ */
+void	kmem_free_wakeup(map, addr, size)
+	vm_map_t	map;
+	vm_offset_t	addr;
+	vm_size_t	size;
+{
+	vm_map_lock(map);
+	(void) vm_map_delete(map, trunc_page(addr), round_page(addr + size));
+	thread_wakeup((int)map);
+	vm_map_unlock(map);
+}
+
+/*
+ * Create the kernel map; insert a mapping covering kernel text, data, bss,
+ * and all space allocated thus far (`boostrap' data).  The new map will thus
+ * map the range between VM_MIN_KERNEL_ADDRESS and `start' as allocated, and
+ * the range between `start' and `end' as free.
+ */
+void kmem_init(start, end)
+	vm_offset_t start, end;
+{
+	register vm_map_t m;
+
+	m = vm_map_create(kernel_pmap, VM_MIN_KERNEL_ADDRESS, end, FALSE);
+	vm_map_lock(m);
+	/* N.B.: cannot use kgdb to debug, starting with this assignment ... */
+	kernel_map = m;
+	(void) vm_map_insert(m, NULL, (vm_offset_t)0,
+	    VM_MIN_KERNEL_ADDRESS, start);
+	/* ... and ending with the completion of the above `insert' */
+	vm_map_unlock(m);
+}