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| Current File : //sys/vm/vm_kern.c |
/*-
* 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.
* 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.
*
* from: @(#)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/cdefs.h>
__FBSDID("$FreeBSD: release/9.1.0/sys/vm/vm_kern.c 237949 2012-07-02 03:49:52Z alc $");
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h> /* for ticks and hz */
#include <sys/eventhandler.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/proc.h>
#include <sys/malloc.h>
#include <sys/sysctl.h>
#include <vm/vm.h>
#include <vm/vm_param.h>
#include <vm/pmap.h>
#include <vm/vm_map.h>
#include <vm/vm_object.h>
#include <vm/vm_page.h>
#include <vm/vm_pageout.h>
#include <vm/vm_extern.h>
#include <vm/uma.h>
vm_map_t kernel_map=0;
vm_map_t kmem_map=0;
vm_map_t exec_map=0;
vm_map_t pipe_map;
vm_map_t buffer_map=0;
const void *zero_region;
CTASSERT((ZERO_REGION_SIZE & PAGE_MASK) == 0);
/*
* kmem_alloc_nofault:
*
* Allocate a virtual address range with no underlying object and
* no initial mapping to physical memory. Any mapping from this
* range to physical memory must be explicitly created prior to
* its use, typically with pmap_qenter(). Any attempt to create
* a mapping on demand through vm_fault() will result in a panic.
*/
vm_offset_t
kmem_alloc_nofault(map, size)
vm_map_t map;
vm_size_t size;
{
vm_offset_t addr;
int result;
size = round_page(size);
addr = vm_map_min(map);
result = vm_map_find(map, NULL, 0, &addr, size, VMFS_ANY_SPACE,
VM_PROT_ALL, VM_PROT_ALL, MAP_NOFAULT);
if (result != KERN_SUCCESS) {
return (0);
}
return (addr);
}
/*
* kmem_alloc_nofault_space:
*
* Allocate a virtual address range with no underlying object and
* no initial mapping to physical memory within the specified
* address space. Any mapping from this range to physical memory
* must be explicitly created prior to its use, typically with
* pmap_qenter(). Any attempt to create a mapping on demand
* through vm_fault() will result in a panic.
*/
vm_offset_t
kmem_alloc_nofault_space(map, size, find_space)
vm_map_t map;
vm_size_t size;
int find_space;
{
vm_offset_t addr;
int result;
size = round_page(size);
addr = vm_map_min(map);
result = vm_map_find(map, NULL, 0, &addr, size, find_space,
VM_PROT_ALL, VM_PROT_ALL, MAP_NOFAULT);
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)
vm_map_t map;
vm_size_t size;
{
vm_offset_t addr;
vm_offset_t offset;
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, vm_map_min(map), 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_PROT_ALL, VM_PROT_ALL, 0);
vm_map_unlock(map);
/*
* And finally, mark the data as non-pageable.
*/
(void) vm_map_wire(map, addr, addr + size,
VM_MAP_WIRE_SYSTEM|VM_MAP_WIRE_NOHOLES);
return (addr);
}
/*
* kmem_free:
*
* Release a region of kernel virtual memory allocated
* with kmem_alloc, and return the physical pages
* associated with that region.
*
* This routine may not block on kernel maps.
*/
void
kmem_free(map, addr, size)
vm_map_t map;
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
* min, max Returned endpoints of map
* size Size of range to find
* superpage_align Request that min is superpage aligned
*/
vm_map_t
kmem_suballoc(vm_map_t parent, vm_offset_t *min, vm_offset_t *max,
vm_size_t size, boolean_t superpage_align)
{
int ret;
vm_map_t result;
size = round_page(size);
*min = vm_map_min(parent);
ret = vm_map_find(parent, NULL, 0, min, size, superpage_align ?
VMFS_ALIGNED_SPACE : VMFS_ANY_SPACE, VM_PROT_ALL, VM_PROT_ALL,
MAP_ACC_NO_CHARGE);
if (ret != KERN_SUCCESS)
panic("kmem_suballoc: bad status return of %d", ret);
*max = *min + size;
result = vm_map_create(vm_map_pmap(parent), *min, *max);
if (result == NULL)
panic("kmem_suballoc: cannot create submap");
if (vm_map_submap(parent, *min, *max, result) != KERN_SUCCESS)
panic("kmem_suballoc: unable to change range to submap");
return (result);
}
/*
* kmem_malloc:
*
* 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.
*
* We don't worry about expanding the map (adding entries) since entries
* for wired maps are statically allocated.
*
* `map' is ONLY allowed to be kmem_map or one of the mbuf submaps to
* which we never free.
*/
vm_offset_t
kmem_malloc(map, size, flags)
vm_map_t map;
vm_size_t size;
int flags;
{
vm_offset_t addr;
int i, rv;
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, vm_map_min(map), size, &addr)) {
vm_map_unlock(map);
if ((flags & M_NOWAIT) == 0) {
for (i = 0; i < 8; i++) {
EVENTHANDLER_INVOKE(vm_lowmem, 0);
uma_reclaim();
vm_map_lock(map);
if (vm_map_findspace(map, vm_map_min(map),
size, &addr) == 0) {
break;
}
vm_map_unlock(map);
tsleep(&i, 0, "nokva", (hz / 4) * (i + 1));
}
if (i == 8) {
panic("kmem_malloc(%ld): kmem_map too small: %ld total allocated",
(long)size, (long)map->size);
}
} else {
return (0);
}
}
rv = kmem_back(map, addr, size, flags);
vm_map_unlock(map);
return (rv == KERN_SUCCESS ? addr : 0);
}
/*
* kmem_back:
*
* Allocate physical pages for the specified virtual address range.
*/
int
kmem_back(vm_map_t map, vm_offset_t addr, vm_size_t size, int flags)
{
vm_offset_t offset, i;
vm_map_entry_t entry;
vm_page_t m;
int pflags;
boolean_t found;
KASSERT(vm_map_locked(map), ("kmem_back: map %p is not locked", map));
offset = addr - VM_MIN_KERNEL_ADDRESS;
vm_object_reference(kmem_object);
vm_map_insert(map, kmem_object, offset, addr, addr + size,
VM_PROT_ALL, VM_PROT_ALL, 0);
/*
* Assert: vm_map_insert() will never be able to extend the
* previous entry so vm_map_lookup_entry() will find a new
* entry exactly corresponding to this address range and it
* will have wired_count == 0.
*/
found = vm_map_lookup_entry(map, addr, &entry);
KASSERT(found && entry->start == addr && entry->end == addr + size &&
entry->wired_count == 0 && (entry->eflags & MAP_ENTRY_IN_TRANSITION)
== 0, ("kmem_back: entry not found or misaligned"));
if ((flags & (M_NOWAIT|M_USE_RESERVE)) == M_NOWAIT)
pflags = VM_ALLOC_INTERRUPT | VM_ALLOC_WIRED;
else
pflags = VM_ALLOC_SYSTEM | VM_ALLOC_WIRED;
if (flags & M_ZERO)
pflags |= VM_ALLOC_ZERO;
if (flags & M_NODUMP)
pflags |= VM_ALLOC_NODUMP;
VM_OBJECT_LOCK(kmem_object);
for (i = 0; i < size; i += PAGE_SIZE) {
retry:
m = vm_page_alloc(kmem_object, OFF_TO_IDX(offset + i), pflags);
/*
* 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) {
if ((flags & M_NOWAIT) == 0) {
VM_OBJECT_UNLOCK(kmem_object);
entry->eflags |= MAP_ENTRY_IN_TRANSITION;
vm_map_unlock(map);
VM_WAIT;
vm_map_lock(map);
KASSERT(
(entry->eflags & (MAP_ENTRY_IN_TRANSITION | MAP_ENTRY_NEEDS_WAKEUP)) ==
MAP_ENTRY_IN_TRANSITION,
("kmem_back: volatile entry"));
entry->eflags &= ~MAP_ENTRY_IN_TRANSITION;
VM_OBJECT_LOCK(kmem_object);
goto retry;
}
/*
* Free the pages before removing the map entry.
* They are already marked busy. Calling
* vm_map_delete before the pages has been freed or
* unbusied will cause a deadlock.
*/
while (i != 0) {
i -= PAGE_SIZE;
m = vm_page_lookup(kmem_object,
OFF_TO_IDX(offset + i));
vm_page_unwire(m, 0);
vm_page_free(m);
}
VM_OBJECT_UNLOCK(kmem_object);
vm_map_delete(map, addr, addr + size);
return (KERN_NO_SPACE);
}
if (flags & M_ZERO && (m->flags & PG_ZERO) == 0)
pmap_zero_page(m);
m->valid = VM_PAGE_BITS_ALL;
KASSERT((m->oflags & VPO_UNMANAGED) != 0,
("kmem_malloc: page %p is managed", m));
}
VM_OBJECT_UNLOCK(kmem_object);
/*
* Mark map entry as non-pageable. Repeat the assert.
*/
KASSERT(entry->start == addr && entry->end == addr + size &&
entry->wired_count == 0,
("kmem_back: entry not found or misaligned after allocation"));
entry->wired_count = 1;
/*
* At this point, the kmem_object must be unlocked because
* vm_map_simplify_entry() calls vm_object_deallocate(), which
* locks the kmem_object.
*/
vm_map_simplify_entry(map, entry);
/*
* Loop thru pages, entering them in the pmap.
*/
VM_OBJECT_LOCK(kmem_object);
for (i = 0; i < size; i += PAGE_SIZE) {
m = vm_page_lookup(kmem_object, OFF_TO_IDX(offset + i));
/*
* Because this is kernel_pmap, this call will not block.
*/
pmap_enter(kernel_pmap, addr + i, VM_PROT_ALL, m, VM_PROT_ALL,
TRUE);
vm_page_wakeup(m);
}
VM_OBJECT_UNLOCK(kmem_object);
return (KERN_SUCCESS);
}
/*
* 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.
*
* This routine may block.
*/
vm_offset_t
kmem_alloc_wait(map, size)
vm_map_t map;
vm_size_t size;
{
vm_offset_t addr;
size = round_page(size);
if (!swap_reserve(size))
return (0);
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, vm_map_min(map), 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);
swap_release(size);
return (0);
}
map->needs_wakeup = TRUE;
vm_map_unlock_and_wait(map, 0);
}
vm_map_insert(map, NULL, 0, addr, addr + size, VM_PROT_ALL,
VM_PROT_ALL, MAP_ACC_CHARGED);
vm_map_unlock(map);
return (addr);
}
/*
* kmem_free_wakeup:
*
* Returns memory to a submap of the kernel, and wakes up any processes
* 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));
if (map->needs_wakeup) {
map->needs_wakeup = FALSE;
vm_map_wakeup(map);
}
vm_map_unlock(map);
}
static void
kmem_init_zero_region(void)
{
vm_offset_t addr, i;
vm_page_t m;
int error;
/*
* Map a single physical page of zeros to a larger virtual range.
* This requires less looping in places that want large amounts of
* zeros, while not using much more physical resources.
*/
addr = kmem_alloc_nofault(kernel_map, ZERO_REGION_SIZE);
m = vm_page_alloc(NULL, 0, VM_ALLOC_NORMAL |
VM_ALLOC_NOOBJ | VM_ALLOC_WIRED | VM_ALLOC_ZERO);
if ((m->flags & PG_ZERO) == 0)
pmap_zero_page(m);
for (i = 0; i < ZERO_REGION_SIZE; i += PAGE_SIZE)
pmap_qenter(addr + i, &m, 1);
error = vm_map_protect(kernel_map, addr, addr + ZERO_REGION_SIZE,
VM_PROT_READ, TRUE);
KASSERT(error == 0, ("error=%d", error));
zero_region = (const void *)addr;
}
/*
* kmem_init:
*
* 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;
{
vm_map_t m;
m = vm_map_create(kernel_pmap, VM_MIN_KERNEL_ADDRESS, end);
m->system_map = 1;
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_ooffset_t) 0,
#ifdef __amd64__
KERNBASE,
#else
VM_MIN_KERNEL_ADDRESS,
#endif
start, VM_PROT_ALL, VM_PROT_ALL, MAP_NOFAULT);
/* ... and ending with the completion of the above `insert' */
vm_map_unlock(m);
kmem_init_zero_region();
}
#ifdef DIAGNOSTIC
/*
* Allow userspace to directly trigger the VM drain routine for testing
* purposes.
*/
static int
debug_vm_lowmem(SYSCTL_HANDLER_ARGS)
{
int error, i;
i = 0;
error = sysctl_handle_int(oidp, &i, 0, req);
if (error)
return (error);
if (i)
EVENTHANDLER_INVOKE(vm_lowmem, 0);
return (0);
}
SYSCTL_PROC(_debug, OID_AUTO, vm_lowmem, CTLTYPE_INT | CTLFLAG_RW, 0, 0,
debug_vm_lowmem, "I", "set to trigger vm_lowmem event");
#endif