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GNU OSKit-Mach
/*
* Mach Operating System
* Copyright (c) 1991,1990,1989,1988,1987 Carnegie Mellon University.
* Copyright (c) 1993,1994 The University of Utah and
* the Computer Systems Laboratory (CSL).
* All rights reserved.
*
* 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, THE UNIVERSITY OF UTAH AND CSL ALLOW FREE USE OF
* THIS SOFTWARE IN ITS "AS IS" CONDITION, AND DISCLAIM 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 [email protected]
* School of Computer Science
* Carnegie Mellon University
* Pittsburgh PA 15213-3890
*
* any improvements or extensions that they make and grant Carnegie Mellon
* the rights to redistribute these changes.
*/
/*
* File: vm/vm_object.c
* Author: Avadis Tevanian, Jr., Michael Wayne Young
*
* Virtual memory object module.
*/
#include <norma_vm.h>
#include <mach_pagemap.h>
#if NORMA_VM
#include <norma/xmm_server_rename.h>
#endif /* NORMA_VM */
#include <mach/memory_object.h>
#include "memory_object_default.h"
#include "memory_object_user.h"
#include "vm_param.h"
#include <ipc/ipc_port.h>
#include <ipc/ipc_space.h>
#include <kern/assert.h>
#include <kern/lock.h>
#include <kern/queue.h>
#include <kern/zalloc.h>
#include <kern/debug.h>
#include <vm/memory_object.h>
#include <vm/vm_fault.h>
#include <vm/vm_map.h>
#include <vm/vm_object.h>
#include <vm/vm_page.h>
#include <vm/vm_pageout.h>
void memory_object_release(
ipc_port_t pager,
pager_request_t pager_request,
ipc_port_t pager_name); /* forward */
void vm_object_deactivate_pages(vm_object_t);
/*
* Virtual memory objects maintain the actual data
* associated with allocated virtual memory. A given
* page of memory exists within exactly one object.
*
* An object is only deallocated when all "references"
* are given up. Only one "reference" to a given
* region of an object should be writeable.
*
* Associated with each object is a list of all resident
* memory pages belonging to that object; this list is
* maintained by the "vm_page" module, but locked by the object's
* lock.
*
* Each object also records the memory object port
* that is used by the kernel to request and write
* back data (the memory object port, field "pager"),
* and the ports provided to the memory manager, the server that
* manages that data, to return data and control its
* use (the memory object control port, field "pager_request")
* and for naming (the memory object name port, field "pager_name").
*
* Virtual memory objects are allocated to provide
* zero-filled memory (vm_allocate) or map a user-defined
* memory object into a virtual address space (vm_map).
*
* Virtual memory objects that refer to a user-defined
* memory object are called "permanent", because all changes
* made in virtual memory are reflected back to the
* memory manager, which may then store it permanently.
* Other virtual memory objects are called "temporary",
* meaning that changes need be written back only when
* necessary to reclaim pages, and that storage associated
* with the object can be discarded once it is no longer
* mapped.
*
* A permanent memory object may be mapped into more
* than one virtual address space. Moreover, two threads
* may attempt to make the first mapping of a memory
* object concurrently. Only one thread is allowed to
* complete this mapping; all others wait for the
* "pager_initialized" field is asserted, indicating
* that the first thread has initialized all of the
* necessary fields in the virtual memory object structure.
*
* The kernel relies on a *default memory manager* to
* provide backing storage for the zero-filled virtual
* memory objects. The memory object ports associated
* with these temporary virtual memory objects are only
* generated and passed to the default memory manager
* when it becomes necessary. Virtual memory objects
* that depend on the default memory manager are called
* "internal". The "pager_created" field is provided to
* indicate whether these ports have ever been allocated.
*
* The kernel may also create virtual memory objects to
* hold changed pages after a copy-on-write operation.
* In this case, the virtual memory object (and its
* backing storage -- its memory object) only contain
* those pages that have been changed. The "shadow"
* field refers to the virtual memory object that contains
* the remainder of the contents. The "shadow_offset"
* field indicates where in the "shadow" these contents begin.
* The "copy" field refers to a virtual memory object
* to which changed pages must be copied before changing
* this object, in order to implement another form
* of copy-on-write optimization.
*
* The virtual memory object structure also records
* the attributes associated with its memory object.
* The "pager_ready", "can_persist" and "copy_strategy"
* fields represent those attributes. The "cached_list"
* field is used in the implementation of the persistence
* attribute.
*
* ZZZ Continue this comment.
*/
zone_t vm_object_zone; /* vm backing store zone */
/*
* All wired-down kernel memory belongs to a single virtual
* memory object (kernel_object) to avoid wasting data structures.
*/
vm_object_t kernel_object;
/*
* Virtual memory objects that are not referenced by
* any address maps, but that are allowed to persist
* (an attribute specified by the associated memory manager),
* are kept in a queue (vm_object_cached_list).
*
* When an object from this queue is referenced again,
* for example to make another address space mapping,
* it must be removed from the queue. That is, the
* queue contains *only* objects with zero references.
*
* The kernel may choose to terminate objects from this
* queue in order to reclaim storage. The current policy
* is to permit a fixed maximum number of unreferenced
* objects (vm_object_cached_max).
*
* A simple lock (accessed by routines
* vm_object_cache_{lock,lock_try,unlock}) governs the
* object cache. It must be held when objects are
* added to or removed from the cache (in vm_object_terminate).
* The routines that acquire a reference to a virtual
* memory object based on one of the memory object ports
* must also lock the cache.
*
* Ideally, the object cache should be more isolated
* from the reference mechanism, so that the lock need
* not be held to make simple references.
*/
queue_head_t vm_object_cached_list;
int vm_object_cached_count;
int vm_object_cached_max = 200; /* may be patched*/
decl_simple_lock_data(,vm_object_cached_lock_data)
#define vm_object_cache_lock() \
simple_lock(&vm_object_cached_lock_data)
#define vm_object_cache_lock_try() \
simple_lock_try(&vm_object_cached_lock_data)
#define vm_object_cache_unlock() \
simple_unlock(&vm_object_cached_lock_data)
/*
* Virtual memory objects are initialized from
* a template (see vm_object_allocate).
*
* When adding a new field to the virtual memory
* object structure, be sure to add initialization
* (see vm_object_init).
*/
vm_object_t vm_object_template;
/*
* vm_object_allocate:
*
* Returns a new object with the given size.
*/
vm_object_t _vm_object_allocate(
vm_size_t size)
{
register vm_object_t object;
object = (vm_object_t) zalloc(vm_object_zone);
*object = *vm_object_template;
queue_init(&object->memq);
vm_object_lock_init(object);
object->size = size;
return object;
}
vm_object_t vm_object_allocate(
vm_size_t size)
{
register vm_object_t object;
register ipc_port_t port;
object = _vm_object_allocate(size);
#if !NORMA_VM
port = ipc_port_alloc_kernel();
if (port == IP_NULL)
panic("vm_object_allocate");
object->pager_name = port;
ipc_kobject_set(port, (ipc_kobject_t) object, IKOT_PAGING_NAME);
#endif /* !NORMA_VM */
return object;
}
/*
* vm_object_bootstrap:
*
* Initialize the VM objects module.
*/
void vm_object_bootstrap(void)
{
vm_object_zone = zinit((vm_size_t) sizeof(struct vm_object),
round_page(512*1024),
round_page(12*1024),
0, "objects");
queue_init(&vm_object_cached_list);
simple_lock_init(&vm_object_cached_lock_data);
/*
* Fill in a template object, for quick initialization
*/
vm_object_template = (vm_object_t) zalloc(vm_object_zone);
bzero((char *) vm_object_template, sizeof *vm_object_template);
vm_object_template->ref_count = 1;
vm_object_template->size = 0;
vm_object_template->resident_page_count = 0;
vm_object_template->copy = VM_OBJECT_NULL;
vm_object_template->shadow = VM_OBJECT_NULL;
vm_object_template->shadow_offset = (vm_offset_t) 0;
vm_object_template->pager = IP_NULL;
vm_object_template->paging_offset = 0;
vm_object_template->pager_request = PAGER_REQUEST_NULL;
vm_object_template->pager_name = IP_NULL;
vm_object_template->pager_created = FALSE;
vm_object_template->pager_initialized = FALSE;
vm_object_template->pager_ready = FALSE;
vm_object_template->copy_strategy = MEMORY_OBJECT_COPY_NONE;
/* ignored if temporary, will be reset before
* permanent object becomes ready */
vm_object_template->use_shared_copy = FALSE;
vm_object_template->shadowed = FALSE;
vm_object_template->absent_count = 0;
vm_object_template->all_wanted = 0; /* all bits FALSE */
vm_object_template->paging_in_progress = 0;
vm_object_template->can_persist = FALSE;
vm_object_template->internal = TRUE;
vm_object_template->temporary = TRUE;
vm_object_template->alive = TRUE;
vm_object_template->lock_in_progress = FALSE;
vm_object_template->lock_restart = FALSE;
vm_object_template->use_old_pageout = TRUE; /* XXX change later */
vm_object_template->last_alloc = (vm_offset_t) 0;
#if MACH_PAGEMAP
vm_object_template->existence_info = VM_EXTERNAL_NULL;
#endif /* MACH_PAGEMAP */
/*
* Initialize the "kernel object"
*/
kernel_object = _vm_object_allocate(
VM_MAX_KERNEL_ADDRESS - VM_MIN_KERNEL_ADDRESS);
/*
* Initialize the "submap object". Make it as large as the
* kernel object so that no limit is imposed on submap sizes.
*/
vm_submap_object = _vm_object_allocate(
VM_MAX_KERNEL_ADDRESS - VM_MIN_KERNEL_ADDRESS);
#if MACH_PAGEMAP
vm_external_module_initialize();
#endif /* MACH_PAGEMAP */
}
void vm_object_init(void)
{
#if !NORMA_VM
/*
* Finish initializing the kernel object.
* The submap object doesn't need a name port.
*/
kernel_object->pager_name = ipc_port_alloc_kernel();
ipc_kobject_set(kernel_object->pager_name,
(ipc_kobject_t) kernel_object,
IKOT_PAGING_NAME);
#endif /* !NORMA_VM */
}
/*
* vm_object_reference:
*
* Gets another reference to the given object.
*/
void vm_object_reference(
register vm_object_t object)
{
if (object == VM_OBJECT_NULL)
return;
vm_object_lock(object);
assert(object->ref_count > 0);
object->ref_count++;
vm_object_unlock(object);
}
/*
* vm_object_deallocate:
*
* Release a reference to the specified object,
* gained either through a vm_object_allocate
* or a vm_object_reference call. When all references
* are gone, storage associated with this object
* may be relinquished.
*
* No object may be locked.
*/
void vm_object_deallocate(
register vm_object_t object)
{
vm_object_t temp;
while (object != VM_OBJECT_NULL) {
/*
* The cache holds a reference (uncounted) to
* the object; we must lock it before removing
* the object.
*/
vm_object_cache_lock();
/*
* Lose the reference
*/
vm_object_lock(object);
if (--(object->ref_count) > 0) {
/*
* If there are still references, then
* we are done.
*/
vm_object_unlock(object);
vm_object_cache_unlock();
return;
}
/*
* See whether this object can persist. If so, enter
* it in the cache, then deactivate all of its
* pages.
*/
if (object->can_persist) {
boolean_t overflow;
/*
* Enter the object onto the queue
* of "cached" objects. Remember whether
* we've caused the queue to overflow,
* as a hint.
*/
queue_enter(&vm_object_cached_list, object,
vm_object_t, cached_list);
overflow = (++vm_object_cached_count > vm_object_cached_max);
vm_object_cache_unlock();
vm_object_deactivate_pages(object);
vm_object_unlock(object);
/*
* If we didn't overflow, or if the queue has
* been reduced back to below the specified
* minimum, then quit.
*/
if (!overflow)
return;
while (TRUE) {
vm_object_cache_lock();
if (vm_object_cached_count <=
vm_object_cached_max) {
vm_object_cache_unlock();
return;
}
/*
* If we must trim down the queue, take
* the first object, and proceed to
* terminate it instead of the original
* object. Have to wait for pager init.
* if it's in progress.
*/
object= (vm_object_t)
queue_first(&vm_object_cached_list);
vm_object_lock(object);
if (!(object->pager_created &&
!object->pager_initialized)) {
/*
* Ok to terminate, hang on to lock.
*/
break;
}
vm_object_assert_wait(object,
VM_OBJECT_EVENT_INITIALIZED, FALSE);
vm_object_unlock(object);
vm_object_cache_unlock();
thread_block((void (*)()) 0);
/*
* Continue loop to check if cache still
* needs to be trimmed.
*/
}
/*
* Actually remove object from cache.
*/
queue_remove(&vm_object_cached_list, object,
vm_object_t, cached_list);
vm_object_cached_count--;
assert(object->ref_count == 0);
}
else {
if (object->pager_created &&
!object->pager_initialized) {
/*
* Have to wait for initialization.
* Put reference back and retry
* when it's initialized.
*/
object->ref_count++;
vm_object_assert_wait(object,
VM_OBJECT_EVENT_INITIALIZED, FALSE);
vm_object_unlock(object);
vm_object_cache_unlock();
thread_block((void (*)()) 0);
continue;
}
}
/*
* Take the reference to the shadow object
* out of the object to be destroyed.
*/
temp = object->shadow;
/*
* Destroy the object; the cache lock will
* be released in the process.
*/
vm_object_terminate(object);
/*
* Deallocate the reference to the shadow
* by continuing the loop with that object
* in place of the original.
*/
object = temp;
}
}
boolean_t vm_object_terminate_remove_all = FALSE;
/*
* Routine: vm_object_terminate
* Purpose:
* Free all resources associated with a vm_object.
* In/out conditions:
* Upon entry, the object and the cache must be locked,
* and the object must have no references.
*
* The shadow object reference is left alone.
*
* Upon exit, the cache will be unlocked, and the
* object will cease to exist.
*/
void vm_object_terminate(
register vm_object_t object)
{
register vm_page_t p;
vm_object_t shadow_object;
/*
* Make sure the object isn't already being terminated
*/
assert(object->alive);
object->alive = FALSE;
/*
* Make sure no one can look us up now.
*/
vm_object_remove(object);
vm_object_cache_unlock();
/*
* Detach the object from its shadow if we are the shadow's
* copy.
*/
if ((shadow_object = object->shadow) != VM_OBJECT_NULL) {
vm_object_lock(shadow_object);
assert((shadow_object->copy == object) ||
(shadow_object->copy == VM_OBJECT_NULL));
shadow_object->copy = VM_OBJECT_NULL;
vm_object_unlock(shadow_object);
}
/*
* The pageout daemon might be playing with our pages.
* Now that the object is dead, it won't touch any more
* pages, but some pages might already be on their way out.
* Hence, we wait until the active paging activities have ceased.
*/
vm_object_paging_wait(object, FALSE);
/*
* Clean or free the pages, as appropriate.
* It is possible for us to find busy/absent pages,
* if some faults on this object were aborted.
*/
if ((object->temporary) || (object->pager == IP_NULL)) {
while (!queue_empty(&object->memq)) {
p = (vm_page_t) queue_first(&object->memq);
VM_PAGE_CHECK(p);
if (p->busy && !p->absent)
panic("vm_object_terminate.2 0x%x 0x%x",
object, p);
VM_PAGE_FREE(p);
}
} else while (!queue_empty(&object->memq)) {
p = (vm_page_t) queue_first(&object->memq);
VM_PAGE_CHECK(p);
if (p->busy && !p->absent)
panic("vm_object_terminate.3 0x%x 0x%x", object, p);
vm_page_lock_queues();
VM_PAGE_QUEUES_REMOVE(p);
vm_page_unlock_queues();
if (p->absent || p->private) {
/*
* For private pages, VM_PAGE_FREE just
* leaves the page structure around for
* its owner to clean up. For absent
* pages, the structure is returned to
* the appropriate pool.
*/
goto free_page;
}
if (p->fictitious)
panic("vm_object_terminate.4 0x%x 0x%x", object, p);
if (!p->dirty)
p->dirty = pmap_is_modified(p->phys_addr);
if (p->dirty || p->precious) {
p->busy = TRUE;
vm_pageout_page(p, FALSE, TRUE); /* flush page */
} else {
free_page:
VM_PAGE_FREE(p);
}
}
assert(object->ref_count == 0);
assert(object->paging_in_progress == 0);
/*
* Throw away port rights... note that they may
* already have been thrown away (by vm_object_destroy
* or memory_object_destroy).
*
* Instead of destroying the control and name ports,
* we send all rights off to the memory manager instead,
* using memory_object_terminate.
*/
vm_object_unlock(object);
if (object->pager != IP_NULL) {
/* consumes our rights for pager, pager_request, pager_name */
memory_object_release(object->pager,
object->pager_request,
object->pager_name);
} else if (object->pager_name != IP_NULL) {
/* consumes our right for pager_name */
#if NORMA_VM
ipc_port_release_send(object->pager_name);
#else /* NORMA_VM */
ipc_port_dealloc_kernel(object->pager_name);
#endif /* NORMA_VM */
}
#if MACH_PAGEMAP
vm_external_destroy(object->existence_info);
#endif /* MACH_PAGEMAP */
/*
* Free the space for the object.
*/
zfree(vm_object_zone, (vm_offset_t) object);
}
/*
* Routine: vm_object_pager_wakeup
* Purpose: Wake up anyone waiting for IKOT_PAGER_TERMINATING
*/
void
vm_object_pager_wakeup(
ipc_port_t pager)
{
boolean_t someone_waiting;
/*
* If anyone was waiting for the memory_object_terminate
* to be queued, wake them up now.
*/
vm_object_cache_lock();
assert(ip_kotype(pager) == IKOT_PAGER_TERMINATING);
someone_waiting = (pager->ip_kobject != IKO_NULL);
if (ip_active(pager))
ipc_kobject_set(pager, IKO_NULL, IKOT_NONE);
vm_object_cache_unlock();
if (someone_waiting) {
thread_wakeup((event_t) pager);
}
}
/*
* Routine: memory_object_release
* Purpose: Terminate the pager and release port rights,
* just like memory_object_terminate, except
* that we wake up anyone blocked in vm_object_enter
* waiting for termination message to be queued
* before calling memory_object_init.
*/
void memory_object_release(
ipc_port_t pager,
pager_request_t pager_request,
ipc_port_t pager_name)
{
/*
* Keep a reference to pager port;
* the terminate might otherwise release all references.
*/
ip_reference(pager);
/*
* Terminate the pager.
*/
(void) memory_object_terminate(pager, pager_request, pager_name);
/*
* Wakeup anyone waiting for this terminate
*/
vm_object_pager_wakeup(pager);
/*
* Release reference to pager port.
*/
ip_release(pager);
}
/*
* Routine: vm_object_abort_activity [internal use only]
* Purpose:
* Abort paging requests pending on this object.
* In/out conditions:
* The object is locked on entry and exit.
*/
void vm_object_abort_activity(
vm_object_t object)
{
register
vm_page_t p;
vm_page_t next;
/*
* Abort all activity that would be waiting
* for a result on this memory object.
*
* We could also choose to destroy all pages
* that we have in memory for this object, but
* we don't.
*/
p = (vm_page_t) queue_first(&object->memq);
while (!queue_end(&object->memq, (queue_entry_t) p)) {
next = (vm_page_t) queue_next(&p->listq);
/*
* If it's being paged in, destroy it.
* If an unlock has been requested, start it again.
*/
if (p->busy && p->absent) {
VM_PAGE_FREE(p);
}
else {
if (p->unlock_request != VM_PROT_NONE)
p->unlock_request = VM_PROT_NONE;
PAGE_WAKEUP(p);
}
p = next;
}
/*
* Wake up threads waiting for the memory object to
* become ready.
*/
object->pager_ready = TRUE;
vm_object_wakeup(object, VM_OBJECT_EVENT_PAGER_READY);
}
/*
* Routine: memory_object_destroy [user interface]
* Purpose:
* Shut down a memory object, despite the
* presence of address map (or other) references
* to the vm_object.
* Note:
* This routine may be called either from the user interface,
* or from port destruction handling (via vm_object_destroy).
*/
kern_return_t memory_object_destroy(
register
vm_object_t object,
kern_return_t reason)
{
ipc_port_t old_object, old_name;
pager_request_t old_control;
#ifdef lint
reason++;
#endif /* lint */
if (object == VM_OBJECT_NULL)
return KERN_SUCCESS;
/*
* Remove the port associations immediately.
*
* This will prevent the memory manager from further
* meddling. [If it wanted to flush data or make
* other changes, it should have done so before performing
* the destroy call.]
*/
vm_object_cache_lock();
vm_object_lock(object);
vm_object_remove(object);
object->can_persist = FALSE;
vm_object_cache_unlock();
/*
* Rip out the ports from the vm_object now... this
* will prevent new memory_object calls from succeeding.
*/
old_object = object->pager;
object->pager = IP_NULL;
old_control = object->pager_request;
object->pager_request = PAGER_REQUEST_NULL;
old_name = object->pager_name;
object->pager_name = IP_NULL;
/*
* Wait for existing paging activity (that might
* have the old ports) to subside.
*/
vm_object_paging_wait(object, FALSE);
vm_object_unlock(object);
/*
* Shut down the ports now.
*
* [Paging operations may be proceeding concurrently --
* they'll get the null values established above.]
*/
if (old_object != IP_NULL) {
/* consumes our rights for object, control, name */
memory_object_release(old_object, old_control,
old_name);
} else if (old_name != IP_NULL) {
/* consumes our right for name */
#if NORMA_VM
ipc_port_release_send(object->pager_name);
#else /* NORMA_VM */
ipc_port_dealloc_kernel(object->pager_name);
#endif /* NORMA_VM */
}
/*
* Lose the reference that was donated for this routine
*/
vm_object_deallocate(object);
return KERN_SUCCESS;
}
/*
* vm_object_deactivate_pages
*
* Deactivate all pages in the specified object. (Keep its pages
* in memory even though it is no longer referenced.)
*
* The object must be locked.
*/
void vm_object_deactivate_pages(
register vm_object_t object)
{
register vm_page_t p;
queue_iterate(&object->memq, p, vm_page_t, listq) {
vm_page_lock_queues();
if (!p->busy)
vm_page_deactivate(p);
vm_page_unlock_queues();
}
}
/*
* Routine: vm_object_pmap_protect
*
* Purpose:
* Reduces the permission for all physical
* pages in the specified object range.
*
* If removing write permission only, it is
* sufficient to protect only the pages in
* the top-level object; only those pages may
* have write permission.
*
* If removing all access, we must follow the
* shadow chain from the top-level object to
* remove access to all pages in shadowed objects.
*
* The object must *not* be locked. The object must
* be temporary/internal.
*
* If pmap is not NULL, this routine assumes that
* the only mappings for the pages are in that
* pmap.
*/
boolean_t vm_object_pmap_protect_by_page = FALSE;
void vm_object_pmap_protect(
register vm_object_t object,
register vm_offset_t offset,
vm_offset_t size,
pmap_t pmap,
vm_offset_t pmap_start,
vm_prot_t prot)
{
if (object == VM_OBJECT_NULL)
return;
vm_object_lock(object);
assert(object->temporary && object->internal);
while (TRUE) {
if (object->resident_page_count > atop(size) / 2 &&
pmap != PMAP_NULL) {
vm_object_unlock(object);
pmap_protect(pmap, pmap_start, pmap_start + size, prot);
return;
}
{
register vm_page_t p;
register vm_offset_t end;
end = offset + size;
queue_iterate(&object->memq, p, vm_page_t, listq) {
if (!p->fictitious &&
(offset <= p->offset) &&
(p->offset < end)) {
if ((pmap == PMAP_NULL) ||
vm_object_pmap_protect_by_page) {
pmap_page_protect(p->phys_addr,
prot & ~p->page_lock);
} else {
vm_offset_t start =
pmap_start +
(p->offset - offset);
pmap_protect(pmap,
start,
start + PAGE_SIZE,
prot);
}
}
}
}
if (prot == VM_PROT_NONE) {
/*
* Must follow shadow chain to remove access
* to pages in shadowed objects.
*/
register vm_object_t next_object;
next_object = object->shadow;
if (next_object != VM_OBJECT_NULL) {
offset += object->shadow_offset;
vm_object_lock(next_object);
vm_object_unlock(object);
object = next_object;
}
else {
/*
* End of chain - we are done.
*/
break;
}
}
else {
/*
* Pages in shadowed objects may never have
* write permission - we may stop here.
*/
break;
}
}
vm_object_unlock(object);
}
/*
* vm_object_pmap_remove:
*
* Removes all physical pages in the specified
* object range from all physical maps.
*
* The object must *not* be locked.
*/
void vm_object_pmap_remove(
register vm_object_t object,
register vm_offset_t start,
register vm_offset_t end)
{
register vm_page_t p;
if (object == VM_OBJECT_NULL)
return;
vm_object_lock(object);
queue_iterate(&object->memq, p, vm_page_t, listq) {
if (!p->fictitious &&
(start <= p->offset) &&
(p->offset < end))
pmap_page_protect(p->phys_addr, VM_PROT_NONE);
}
vm_object_unlock(object);
}
/*
* Routine: vm_object_copy_slowly
*
* Description:
* Copy the specified range of the source
* virtual memory object without using
* protection-based optimizations (such
* as copy-on-write). The pages in the
* region are actually copied.
*
* In/out conditions:
* The caller must hold a reference and a lock
* for the source virtual memory object. The source
* object will be returned *unlocked*.
*
* Results:
* If the copy is completed successfully, KERN_SUCCESS is
* returned. If the caller asserted the interruptible
* argument, and an interruption occurred while waiting
* for a user-generated event, MACH_SEND_INTERRUPTED is
* returned. Other values may be returned to indicate
* hard errors during the copy operation.
*
* A new virtual memory object is returned in a
* parameter (_result_object). The contents of this
* new object, starting at a zero offset, are a copy
* of the source memory region. In the event of
* an error, this parameter will contain the value
* VM_OBJECT_NULL.
*/
kern_return_t vm_object_copy_slowly(
register
vm_object_t src_object,
vm_offset_t src_offset,
vm_size_t size,
boolean_t interruptible,
vm_object_t *_result_object) /* OUT */
{
vm_object_t new_object;
vm_offset_t new_offset;
if (size == 0) {
vm_object_unlock(src_object);
*_result_object = VM_OBJECT_NULL;
return KERN_INVALID_ARGUMENT;
}
/*
* Prevent destruction of the source object while we copy.
*/
assert(src_object->ref_count > 0);
src_object->ref_count++;
vm_object_unlock(src_object);
/*
* Create a new object to hold the copied pages.
* A few notes:
* We fill the new object starting at offset 0,
* regardless of the input offset.
* We don't bother to lock the new object within
* this routine, since we have the only reference.
*/
new_object = vm_object_allocate(size);
new_offset = 0;
assert(size == trunc_page(size)); /* Will the loop terminate? */
for ( ;
size != 0 ;
src_offset += PAGE_SIZE, new_offset += PAGE_SIZE, size -= PAGE_SIZE
) {
vm_page_t new_page;
vm_fault_return_t result;
while ((new_page = vm_page_alloc(new_object, new_offset))
== VM_PAGE_NULL) {
VM_PAGE_WAIT((void (*)()) 0);
}
do {
vm_prot_t prot = VM_PROT_READ;
vm_page_t _result_page;
vm_page_t top_page;
register
vm_page_t result_page;
vm_object_lock(src_object);
src_object->paging_in_progress++;
result = vm_fault_page(src_object, src_offset,
VM_PROT_READ, FALSE, interruptible,
&prot, &_result_page, &top_page,
FALSE, (void (*)()) 0);
switch(result) {
case VM_FAULT_SUCCESS:
result_page = _result_page;
/*
* We don't need to hold the object
* lock -- the busy page will be enough.
* [We don't care about picking up any
* new modifications.]
*
* Copy the page to the new object.
*
* POLICY DECISION:
* If result_page is clean,
* we could steal it instead
* of copying.
*/
vm_object_unlock(result_page->object);
vm_page_copy(result_page, new_page);
/*
* Let go of both pages (make them
* not busy, perform wakeup, activate).
*/
new_page->busy = FALSE;
new_page->dirty = TRUE;
vm_object_lock(result_page->object);
PAGE_WAKEUP_DONE(result_page);
vm_page_lock_queues();
if (!result_page->active &&
!result_page->inactive)
vm_page_activate(result_page);
vm_page_activate(new_page);
vm_page_unlock_queues();
/*
* Release paging references and
* top-level placeholder page, if any.
*/
vm_fault_cleanup(result_page->object,
top_page);
break;
case VM_FAULT_RETRY:
break;
case VM_FAULT_MEMORY_SHORTAGE:
VM_PAGE_WAIT((void (*)()) 0);
break;
case VM_FAULT_FICTITIOUS_SHORTAGE:
vm_page_more_fictitious();
break;
case VM_FAULT_INTERRUPTED:
vm_page_free(new_page);
vm_object_deallocate(new_object);
vm_object_deallocate(src_object);
*_result_object = VM_OBJECT_NULL;
return MACH_SEND_INTERRUPTED;
case VM_FAULT_MEMORY_ERROR:
/*
* A policy choice:
* (a) ignore pages that we can't
* copy
* (b) return the null object if
* any page fails [chosen]
*/
vm_page_free(new_page);
vm_object_deallocate(new_object);
vm_object_deallocate(src_object);
*_result_object = VM_OBJECT_NULL;
return KERN_MEMORY_ERROR;
}
} while (result != VM_FAULT_SUCCESS);
}
/*
* Lose the extra reference, and return our object.
*/
vm_object_deallocate(src_object);
*_result_object = new_object;
return KERN_SUCCESS;
}
/*
* Routine: vm_object_copy_temporary
*
* Purpose:
* Copy the specified range of the source virtual
* memory object, if it can be done without blocking.
*
* Results:
* If the copy is successful, the copy is returned in
* the arguments; otherwise, the arguments are not
* affected.
*
* In/out conditions:
* The object should be unlocked on entry and exit.
*/
vm_object_t vm_object_copy_delayed(); /* forward declaration */
boolean_t vm_object_copy_temporary(
vm_object_t *_object, /* INOUT */
vm_offset_t *_offset, /* INOUT */
boolean_t *_src_needs_copy, /* OUT */
boolean_t *_dst_needs_copy) /* OUT */
{
vm_object_t object = *_object;
#ifdef lint
++*_offset;
#endif /* lint */
if (object == VM_OBJECT_NULL) {
*_src_needs_copy = FALSE;
*_dst_needs_copy = FALSE;
return TRUE;
}
/*
* If the object is temporary, we can perform
* a symmetric copy-on-write without asking.
*/
vm_object_lock(object);
if (object->temporary) {
/*
* Shared objects use delayed copy
*/
if (object->use_shared_copy) {
/*
* Asymmetric copy strategy. Destination
* must be copied (to allow copy object reuse).
* Source is unaffected.
*/
vm_object_unlock(object);
object = vm_object_copy_delayed(object);
*_object = object;
*_src_needs_copy = FALSE;
*_dst_needs_copy = TRUE;
return TRUE;
}
/*
* Make another reference to the object.
*
* Leave object/offset unchanged.
*/
assert(object->ref_count > 0);
object->ref_count++;
object->shadowed = TRUE;
vm_object_unlock(object);
/*
* Both source and destination must make
* shadows, and the source must be made
* read-only if not already.
*/
*_src_needs_copy = TRUE;
*_dst_needs_copy = TRUE;
return TRUE;
}
if (object->pager_ready &&
(object->copy_strategy == MEMORY_OBJECT_COPY_DELAY)) {
/* XXX Do something intelligent (see temporary code above) */
}
vm_object_unlock(object);
return FALSE;
}
/*
* Routine: vm_object_copy_call [internal]
*
* Description:
* Copy the specified (src_offset, size) portion
* of the source object (src_object), using the
* user-managed copy algorithm.
*
* In/out conditions:
* The source object must be locked on entry. It
* will be *unlocked* on exit.
*
* Results:
* If the copy is successful, KERN_SUCCESS is returned.
* This routine is interruptible; if a wait for
* a user-generated event is interrupted, MACH_SEND_INTERRUPTED
* is returned. Other return values indicate hard errors
* in creating the user-managed memory object for the copy.
*
* A new object that represents the copied virtual
* memory is returned in a parameter (*_result_object).
* If the return value indicates an error, this parameter
* is not valid.
*/
kern_return_t vm_object_copy_call(
vm_object_t src_object,
vm_offset_t src_offset,
vm_size_t size,
vm_object_t *_result_object) /* OUT */
{
vm_offset_t src_end = src_offset + size;
ipc_port_t new_memory_object;
vm_object_t new_object;
vm_page_t p;
/*
* Set the backing object for the new
* temporary object.
*/
assert(src_object->ref_count > 0);
src_object->ref_count++;
vm_object_paging_begin(src_object);
vm_object_unlock(src_object);
/*
* Create a memory object port to be associated
* with this new vm_object.
*
* Since the kernel has the only rights to this
* port, we need not hold the cache lock.
*
* Since we have the only object reference, we
* need not be worried about collapse operations.
*
*/
new_memory_object = ipc_port_alloc_kernel();
if (new_memory_object == IP_NULL) {
panic("vm_object_copy_call: allocate memory object port");
/* XXX Shouldn't panic here. */
}
/* we hold a naked receive right for new_memory_object */
(void) ipc_port_make_send(new_memory_object);
/* now we also hold a naked send right for new_memory_object */
/*
* Let the memory manager know that a copy operation
* is in progress. Note that we're using the old
* memory object's ports (for which we're holding
* a paging reference)... the memory manager cannot
* yet affect the new memory object.
*/
(void) memory_object_copy(src_object->pager,
src_object->pager_request,
src_offset, size,
new_memory_object);
/* no longer hold the naked receive right for new_memory_object */
vm_object_lock(src_object);
vm_object_paging_end(src_object);
/*
* Remove write access from all of the pages of
* the old memory object that we can.
*/
queue_iterate(&src_object->memq, p, vm_page_t, listq) {
if (!p->fictitious &&
(src_offset <= p->offset) &&
(p->offset < src_end) &&
!(p->page_lock & VM_PROT_WRITE)) {
p->page_lock |= VM_PROT_WRITE;
pmap_page_protect(p->phys_addr, VM_PROT_ALL & ~p->page_lock);
}
}
vm_object_unlock(src_object);
/*
* Initialize the rest of the paging stuff
*/
new_object = vm_object_enter(new_memory_object, size, FALSE);
new_object->shadow = src_object;
new_object->shadow_offset = src_offset;
/*
* Drop the reference for new_memory_object taken above.
*/
ipc_port_release_send(new_memory_object);
/* no longer hold the naked send right for new_memory_object */
*_result_object = new_object;
return KERN_SUCCESS;
}
/*
* Routine: vm_object_copy_delayed [internal]
*
* Description:
* Copy the specified virtual memory object, using
* the asymmetric copy-on-write algorithm.
*
* In/out conditions:
* The object must be unlocked on entry.
*
* This routine will not block waiting for user-generated
* events. It is not interruptible.
*/
vm_object_t vm_object_copy_delayed(
vm_object_t src_object)
{
vm_object_t new_copy;
vm_object_t old_copy;
vm_page_t p;
/*
* The user-level memory manager wants to see
* all of the changes to this object, but it
* has promised not to make any changes on its own.
*
* Perform an asymmetric copy-on-write, as follows:
* Create a new object, called a "copy object"
* to hold pages modified by the new mapping
* (i.e., the copy, not the original mapping).
* Record the original object as the backing
* object for the copy object. If the
* original mapping does not change a page,
* it may be used read-only by the copy.
* Record the copy object in the original
* object. When the original mapping causes
* a page to be modified, it must be copied
* to a new page that is "pushed" to the
* copy object.
* Mark the new mapping (the copy object)
* copy-on-write. This makes the copy
* object itself read-only, allowing it
* to be reused if the original mapping
* makes no changes, and simplifying the
* synchronization required in the "push"
* operation described above.
*
* The copy-on-write is said to be assymetric because
* the original object is *not* marked copy-on-write.
* A copied page is pushed to the copy object, regardless
* which party attempted to modify the page.
*
* Repeated asymmetric copy operations may be done.
* If the original object has not been changed since
* the last copy, its copy object can be reused.
* Otherwise, a new copy object can be inserted
* between the original object and its previous
* copy object. Since any copy object is read-only,
* this cannot affect the contents of the previous copy
* object.
*
* Note that a copy object is higher in the object
* tree than the original object; therefore, use of
* the copy object recorded in the original object
* must be done carefully, to avoid deadlock.
*/
/*
* Allocate a new copy object before locking, even
* though we may not need it later.
*/
new_copy = vm_object_allocate(src_object->size);
vm_object_lock(src_object);
/*
* See whether we can reuse the result of a previous
* copy operation.
*/
Retry:
old_copy = src_object->copy;
if (old_copy != VM_OBJECT_NULL) {
/*
* Try to get the locks (out of order)
*/
if (!vm_object_lock_try(old_copy)) {
vm_object_unlock(src_object);
simple_lock_pause(); /* wait a bit */
vm_object_lock(src_object);
goto Retry;
}
/*
* Determine whether the old copy object has
* been modified.
*/
if (old_copy->resident_page_count == 0 &&
!old_copy->pager_created) {
/*
* It has not been modified.
*
* Return another reference to
* the existing copy-object.
*/
assert(old_copy->ref_count > 0);
old_copy->ref_count++;
vm_object_unlock(old_copy);
vm_object_unlock(src_object);
vm_object_deallocate(new_copy);
return old_copy;
}
/*
* The copy-object is always made large enough to
* completely shadow the original object, since
* it may have several users who want to shadow
* the original object at different points.
*/
assert((old_copy->shadow == src_object) &&
(old_copy->shadow_offset == (vm_offset_t) 0));
/*
* Make the old copy-object shadow the new one.
* It will receive no more pages from the original
* object.
*/
src_object->ref_count--; /* remove ref. from old_copy */
assert(src_object->ref_count > 0);
old_copy->shadow = new_copy;
assert(new_copy->ref_count > 0);
new_copy->ref_count++;
vm_object_unlock(old_copy); /* done with old_copy */
}
/*
* Point the new copy at the existing object.
*/
new_copy->shadow = src_object;
new_copy->shadow_offset = 0;
new_copy->shadowed = TRUE; /* caller must set needs_copy */
assert(src_object->ref_count > 0);
src_object->ref_count++;
src_object->copy = new_copy;
/*
* Mark all pages of the existing object copy-on-write.
* This object may have a shadow chain below it, but
* those pages will already be marked copy-on-write.
*/
queue_iterate(&src_object->memq, p, vm_page_t, listq) {
if (!p->fictitious)
pmap_page_protect(p->phys_addr,
(VM_PROT_ALL & ~VM_PROT_WRITE &
~p->page_lock));
}
vm_object_unlock(src_object);
return new_copy;
}
/*
* Routine: vm_object_copy_strategically
*
* Purpose:
* Perform a copy according to the source object's
* declared strategy. This operation may block,
* and may be interrupted.
*/
kern_return_t vm_object_copy_strategically(
register
vm_object_t src_object,
vm_offset_t src_offset,
vm_size_t size,
vm_object_t *dst_object, /* OUT */
vm_offset_t *dst_offset, /* OUT */
boolean_t *dst_needs_copy) /* OUT */
{
kern_return_t result = KERN_SUCCESS; /* to quiet gcc warnings */
boolean_t interruptible = TRUE; /* XXX */
assert(src_object != VM_OBJECT_NULL);
vm_object_lock(src_object);
/* XXX assert(!src_object->temporary); JSB FIXME */
/*
* The copy strategy is only valid if the memory manager
* is "ready".
*/
while (!src_object->pager_ready) {
vm_object_wait( src_object,
VM_OBJECT_EVENT_PAGER_READY,
interruptible);
if (interruptible &&
(current_thread()->wait_result != THREAD_AWAKENED)) {
*dst_object = VM_OBJECT_NULL;
*dst_offset = 0;
*dst_needs_copy = FALSE;
return MACH_SEND_INTERRUPTED;
}
vm_object_lock(src_object);
}
/*
* The object may be temporary (even though it is external).
* If so, do a symmetric copy.
*/
if (src_object->temporary) {
/*
* XXX
* This does not count as intelligent!
* This buys us the object->temporary optimizations,
* but we aren't using a symmetric copy,
* which may confuse the vm code. The correct thing
* to do here is to figure out what to call to get
* a temporary shadowing set up.
*/
src_object->copy_strategy = MEMORY_OBJECT_COPY_DELAY;
}
/*
* The object is permanent. Use the appropriate copy strategy.
*/
switch (src_object->copy_strategy) {
case MEMORY_OBJECT_COPY_NONE:
if ((result = vm_object_copy_slowly(
src_object,
src_offset,
size,
interruptible,
dst_object))
== KERN_SUCCESS) {
*dst_offset = 0;
*dst_needs_copy = FALSE;
}
break;
case MEMORY_OBJECT_COPY_CALL:
if ((result = vm_object_copy_call(
src_object,
src_offset,
size,
dst_object))
== KERN_SUCCESS) {
*dst_offset = 0;
*dst_needs_copy = FALSE;
}
break;
case MEMORY_OBJECT_COPY_DELAY:
vm_object_unlock(src_object);
*dst_object = vm_object_copy_delayed(src_object);
*dst_offset = src_offset;
*dst_needs_copy = TRUE;
result = KERN_SUCCESS;
break;
}
return result;
}
/*
* vm_object_shadow:
*
* Create a new object which is backed by the
* specified existing object range. The source
* object reference is deallocated.
*
* The new object and offset into that object
* are returned in the source parameters.
*/
void vm_object_shadow(
vm_object_t *object, /* IN/OUT */
vm_offset_t *offset, /* IN/OUT */
vm_size_t length)
{
register vm_object_t source;
register vm_object_t result;
source = *object;
/*
* Allocate a new object with the given length
*/
if ((result = vm_object_allocate(length)) == VM_OBJECT_NULL)
panic("vm_object_shadow: no object for shadowing");
/*
* The new object shadows the source object, adding
* a reference to it. Our caller changes his reference
* to point to the new object, removing a reference to
* the source object. Net result: no change of reference
* count.
*/
result->shadow = source;
/*
* Store the offset into the source object,
* and fix up the offset into the new object.
*/
result->shadow_offset = *offset;
/*
* Return the new things
*/
*offset = 0;
*object = result;
}
/*
* The relationship between vm_object structures and
* the memory_object ports requires careful synchronization.
*
* All associations are created by vm_object_enter. All three
* port fields are filled in, as follows:
* pager: the memory_object port itself, supplied by
* the user requesting a mapping (or the kernel,
* when initializing internal objects); the
* kernel simulates holding send rights by keeping
* a port reference;
* pager_request:
* pager_name:
* the memory object control and name ports,
* created by the kernel; the kernel holds
* receive (and ownership) rights to these
* ports, but no other references.
* All of the ports are referenced by their global names.
*
* When initialization is complete, the "initialized" field
* is asserted. Other mappings using a particular memory object,
* and any references to the vm_object gained through the
* port association must wait for this initialization to occur.
*
* In order to allow the memory manager to set attributes before
* requests (notably virtual copy operations, but also data or
* unlock requests) are made, a "ready" attribute is made available.
* Only the memory manager may affect the value of this attribute.
* Its value does not affect critical kernel functions, such as
* internal object initialization or destruction. [Furthermore,
* memory objects created by the kernel are assumed to be ready
* immediately; the default memory manager need not explicitly
* set the "ready" attribute.]
*
* [Both the "initialized" and "ready" attribute wait conditions
* use the "pager" field as the wait event.]
*
* The port associations can be broken down by any of the
* following routines:
* vm_object_terminate:
* No references to the vm_object remain, and
* the object cannot (or will not) be cached.
* This is the normal case, and is done even
* though one of the other cases has already been
* done.
* vm_object_destroy:
* The memory_object port has been destroyed,
* meaning that the kernel cannot flush dirty
* pages or request new data or unlock existing
* data.
* memory_object_destroy:
* The memory manager has requested that the
* kernel relinquish rights to the memory object
* port. [The memory manager may not want to
* destroy the port, but may wish to refuse or
* tear down existing memory mappings.]
* Each routine that breaks an association must break all of
* them at once. At some later time, that routine must clear
* the vm_object port fields and release the port rights.
* [Furthermore, each routine must cope with the simultaneous
* or previous operations of the others.]
*
* In addition to the lock on the object, the vm_object_cache_lock
* governs the port associations. References gained through the
* port association require use of the cache lock.
*
* Because the port fields may be cleared spontaneously, they
* cannot be used to determine whether a memory object has
* ever been associated with a particular vm_object. [This
* knowledge is important to the shadow object mechanism.]
* For this reason, an additional "created" attribute is
* provided.
*
* During various paging operations, the port values found in the
* vm_object must be valid. To prevent these port rights from being
* released, and to prevent the port associations from changing
* (other than being removed, i.e., made null), routines may use
* the vm_object_paging_begin/end routines [actually, macros].
* The implementation uses the "paging_in_progress" and "wanted" fields.
* [Operations that alter the validity of the port values include the
* termination routines and vm_object_collapse.]
*/
vm_object_t vm_object_lookup(
ipc_port_t port)
{
vm_object_t object = VM_OBJECT_NULL;
if (IP_VALID(port)) {
ip_lock(port);
if (ip_active(port) &&
#if NORMA_VM
(ip_kotype(port) == IKOT_PAGER)) {
#else /* NORMA_VM */
(ip_kotype(port) == IKOT_PAGING_REQUEST)) {
#endif /* NORMA_VM */
vm_object_cache_lock();
object = (vm_object_t) port->ip_kobject;
vm_object_lock(object);
assert(object->alive);
if (object->ref_count == 0) {
queue_remove(&vm_object_cached_list, object,
vm_object_t, cached_list);
vm_object_cached_count--;
}
object->ref_count++;
vm_object_unlock(object);
vm_object_cache_unlock();
}
ip_unlock(port);
}
return object;
}
vm_object_t vm_object_lookup_name(
ipc_port_t port)
{
vm_object_t object = VM_OBJECT_NULL;
if (IP_VALID(port)) {
ip_lock(port);
if (ip_active(port) &&
(ip_kotype(port) == IKOT_PAGING_NAME)) {
vm_object_cache_lock();
object = (vm_object_t) port->ip_kobject;
vm_object_lock(object);
assert(object->alive);
if (object->ref_count == 0) {
queue_remove(&vm_object_cached_list, object,
vm_object_t, cached_list);
vm_object_cached_count--;
}
object->ref_count++;
vm_object_unlock(object);
vm_object_cache_unlock();
}
ip_unlock(port);
}
return object;
}
void vm_object_destroy(
ipc_port_t pager)
{
vm_object_t object;
pager_request_t old_request;
ipc_port_t old_name;
/*
* Perform essentially the same operations as in vm_object_lookup,
* except that this time we look up based on the memory_object
* port, not the control port.
*/
vm_object_cache_lock();
if (ip_kotype(pager) != IKOT_PAGER) {
vm_object_cache_unlock();
return;
}
object = (vm_object_t) pager->ip_kobject;
vm_object_lock(object);
if (object->ref_count == 0) {
queue_remove(&vm_object_cached_list, object,
vm_object_t, cached_list);
vm_object_cached_count--;
}
object->ref_count++;
object->can_persist = FALSE;
assert(object->pager == pager);
/*
* Remove the port associations.
*
* Note that the memory_object itself is dead, so
* we don't bother with it.
*/
object->pager = IP_NULL;
vm_object_remove(object);
old_request = object->pager_request;
object->pager_request = PAGER_REQUEST_NULL;
old_name = object->pager_name;
object->pager_name = IP_NULL;
vm_object_unlock(object);
vm_object_cache_unlock();
/*
* Clean up the port references. Note that there's no
* point in trying the memory_object_terminate call
* because the memory_object itself is dead.
*/
ipc_port_release_send(pager);
#if !NORMA_VM
if (old_request != IP_NULL)
ipc_port_dealloc_kernel(old_request);
#endif /* !NORMA_VM */
if (old_name != IP_NULL)
#if NORMA_VM
ipc_port_release_send(old_name);
#else /* NORMA_VM */
ipc_port_dealloc_kernel(old_name);
#endif /* NORMA_VM */
/*
* Restart pending page requests
*/
vm_object_abort_activity(object);
/*
* Lose the object reference.
*/
vm_object_deallocate(object);
}
boolean_t vm_object_accept_old_init_protocol = FALSE;
/*
* Routine: vm_object_enter
* Purpose:
* Find a VM object corresponding to the given
* pager; if no such object exists, create one,
* and initialize the pager.
*/
vm_object_t vm_object_enter(
ipc_port_t pager,
vm_size_t size,
boolean_t internal)
{
register
vm_object_t object;
vm_object_t new_object;
boolean_t must_init;
ipc_kobject_type_t po;
restart:
if (!IP_VALID(pager))
return vm_object_allocate(size);
new_object = VM_OBJECT_NULL;
must_init = FALSE;
/*
* Look for an object associated with this port.
*/
vm_object_cache_lock();
for (;;) {
po = ip_kotype(pager);
/*
* If a previous object is being terminated,
* we must wait for the termination message
* to be queued.
*
* We set kobject to a non-null value to let the
* terminator know that someone is waiting.
* Among the possibilities is that the port
* could die while we're waiting. Must restart
* instead of continuing the loop.
*/
if (po == IKOT_PAGER_TERMINATING) {
pager->ip_kobject = (ipc_kobject_t) pager;
assert_wait((event_t) pager, FALSE);
vm_object_cache_unlock();
thread_block((void (*)()) 0);
goto restart;
}
/*
* Bail if there is already a kobject associated
* with the pager port.
*/
if (po != IKOT_NONE) {
break;
}
/*
* We must unlock to create a new object;
* if we do so, we must try the lookup again.
*/
if (new_object == VM_OBJECT_NULL) {
vm_object_cache_unlock();
new_object = vm_object_allocate(size);
vm_object_cache_lock();
} else {
/*
* Lookup failed twice, and we have something
* to insert; set the object.
*/
ipc_kobject_set(pager,
(ipc_kobject_t) new_object,
IKOT_PAGER);
new_object = VM_OBJECT_NULL;
must_init = TRUE;
}
}
if (internal)
must_init = TRUE;
/*
* It's only good if it's a VM object!
*/
object = (po == IKOT_PAGER) ? (vm_object_t) pager->ip_kobject
: VM_OBJECT_NULL;
if ((object != VM_OBJECT_NULL) && !must_init) {
vm_object_lock(object);
if (object->ref_count == 0) {
queue_remove(&vm_object_cached_list, object,
vm_object_t, cached_list);
vm_object_cached_count--;
}
object->ref_count++;
vm_object_unlock(object);
vm_stat.hits++;
}
assert((object == VM_OBJECT_NULL) || (object->ref_count > 0) ||
((object->paging_in_progress != 0) && internal));
vm_stat.lookups++;
vm_object_cache_unlock();
/*
* If we raced to create a vm_object but lost, let's
* throw away ours.
*/
if (new_object != VM_OBJECT_NULL)
vm_object_deallocate(new_object);
if (object == VM_OBJECT_NULL)
return(object);
if (must_init) {
/*
* Copy the naked send right we were given.
*/
pager = ipc_port_copy_send(pager);
if (!IP_VALID(pager))
panic("vm_object_enter: port died"); /* XXX */
object->pager_created = TRUE;
object->pager = pager;
#if NORMA_VM
/*
* Let the xmm system know that we want to use the pager.
*
* Name port will be provided by the xmm system
* when set_attributes_common is called.
*/
object->internal = internal;
object->pager_ready = internal;
if (internal) {
assert(object->temporary);
} else {
object->temporary = FALSE;
}
object->pager_name = IP_NULL;
(void) xmm_memory_object_init(object);
#else /* NORMA_VM */
/*
* Allocate request port.
*/
object->pager_request = ipc_port_alloc_kernel();
if (object->pager_request == IP_NULL)
panic("vm_object_enter: pager request alloc");
ipc_kobject_set(object->pager_request,
(ipc_kobject_t) object,
IKOT_PAGING_REQUEST);
/*
* Let the pager know we're using it.
*/
if (internal) {
/* acquire a naked send right for the DMM */
ipc_port_t DMM = memory_manager_default_reference();
/* mark the object internal */
object->internal = TRUE;
assert(object->temporary);
/* default-pager objects are ready immediately */
object->pager_ready = TRUE;
/* consumes the naked send right for DMM */
(void) memory_object_create(DMM,
pager,
object->size,
object->pager_request,
object->pager_name,
PAGE_SIZE);
} else {
/* the object is external and not temporary */
object->internal = FALSE;
object->temporary = FALSE;
/* user pager objects are not ready until marked so */
object->pager_ready = FALSE;
(void) memory_object_init(pager,
object->pager_request,
object->pager_name,
PAGE_SIZE);
}
#endif /* NORMA_VM */
vm_object_lock(object);
object->pager_initialized = TRUE;
if (vm_object_accept_old_init_protocol)
object->pager_ready = TRUE;
vm_object_wakeup(object, VM_OBJECT_EVENT_INITIALIZED);
} else {
vm_object_lock(object);
}
/*
* [At this point, the object must be locked]
*/
/*
* Wait for the work above to be done by the first
* thread to map this object.
*/
while (!object->pager_initialized) {
vm_object_wait( object,
VM_OBJECT_EVENT_INITIALIZED,
FALSE);
vm_object_lock(object);
}
vm_object_unlock(object);
return object;
}
/*
* Routine: vm_object_pager_create
* Purpose:
* Create a memory object for an internal object.
* In/out conditions:
* The object is locked on entry and exit;
* it may be unlocked within this call.
* Limitations:
* Only one thread may be performing a
* vm_object_pager_create on an object at
* a time. Presumably, only the pageout
* daemon will be using this routine.
*/
void vm_object_pager_create(
register
vm_object_t object)
{
ipc_port_t pager;
if (object->pager_created) {
/*
* Someone else got to it first...
* wait for them to finish initializing
*/
while (!object->pager_initialized) {
vm_object_wait( object,
VM_OBJECT_EVENT_PAGER_READY,
FALSE);
vm_object_lock(object);
}
return;
}
/*
* Indicate that a memory object has been assigned
* before dropping the lock, to prevent a race.
*/
object->pager_created = TRUE;
/*
* Prevent collapse or termination by
* holding a paging reference
*/
vm_object_paging_begin(object);
vm_object_unlock(object);
#if MACH_PAGEMAP
object->existence_info = vm_external_create(
object->size +
object->paging_offset);
assert((object->size + object->paging_offset) >=
object->size);
#endif /* MACH_PAGEMAP */
/*
* Create the pager, and associate with it
* this object.
*
* Note that we only make the port association
* so that vm_object_enter can properly look up
* the object to complete the initialization...
* we do not expect any user to ever map this
* object.
*
* Since the kernel has the only rights to the
* port, it's safe to install the association
* without holding the cache lock.
*/
pager = ipc_port_alloc_kernel();
if (pager == IP_NULL)
panic("vm_object_pager_create: allocate pager port");
(void) ipc_port_make_send(pager);
ipc_kobject_set(pager, (ipc_kobject_t) object, IKOT_PAGER);
/*
* Initialize the rest of the paging stuff
*/
if (vm_object_enter(pager, object->size, TRUE) != object)
panic("vm_object_pager_create: mismatch");
/*
* Drop the naked send right taken above.
*/
ipc_port_release_send(pager);
/*
* Release the paging reference
*/
vm_object_lock(object);
vm_object_paging_end(object);
}
/*
* Routine: vm_object_remove
* Purpose:
* Eliminate the pager/object association
* for this pager.
* Conditions:
* The object cache must be locked.
*/
void vm_object_remove(
vm_object_t object)
{
ipc_port_t port;
if ((port = object->pager) != IP_NULL) {
if (ip_kotype(port) == IKOT_PAGER)
ipc_kobject_set(port, IKO_NULL,
IKOT_PAGER_TERMINATING);
else if (ip_kotype(port) != IKOT_NONE)
panic("vm_object_remove: bad object port");
}
#if !NORMA_VM
if ((port = object->pager_request) != IP_NULL) {
if (ip_kotype(port) == IKOT_PAGING_REQUEST)
ipc_kobject_set(port, IKO_NULL, IKOT_NONE);
else if (ip_kotype(port) != IKOT_NONE)
panic("vm_object_remove: bad request port");
}
if ((port = object->pager_name) != IP_NULL) {
if (ip_kotype(port) == IKOT_PAGING_NAME)
ipc_kobject_set(port, IKO_NULL, IKOT_NONE);
else if (ip_kotype(port) != IKOT_NONE)
panic("vm_object_remove: bad name port");
}
#endif /* !NORMA_VM */
}
/*
* Global variables for vm_object_collapse():
*
* Counts for normal collapses and bypasses.
* Debugging variables, to watch or disable collapse.
*/
long object_collapses = 0;
long object_bypasses = 0;
int vm_object_collapse_debug = 0;
boolean_t vm_object_collapse_allowed = TRUE;
boolean_t vm_object_collapse_bypass_allowed = TRUE;
/*
* vm_object_collapse:
*
* Collapse an object with the object backing it.
* Pages in the backing object are moved into the
* parent, and the backing object is deallocated.
*
* Requires that the object be locked and the page
* queues be unlocked. May unlock/relock the object,
* so the caller should hold a reference for the object.
*/
void vm_object_collapse(
register vm_object_t object)
{
register vm_object_t backing_object;
register vm_offset_t backing_offset;
register vm_size_t size;
register vm_offset_t new_offset;
register vm_page_t p, pp;
ipc_port_t old_name_port;
if (!vm_object_collapse_allowed)
return;
while (TRUE) {
/*
* Verify that the conditions are right for collapse:
*
* The object exists and no pages in it are currently
* being paged out (or have ever been paged out).
*
* This check is probably overkill -- if a memory
* object has not been created, the fault handler
* shouldn't release the object lock while paging
* is in progress or absent pages exist.
*/
if (object == VM_OBJECT_NULL ||
object->pager_created ||
object->paging_in_progress != 0 ||
object->absent_count != 0)
return;
/*
* There is a backing object, and
*/
if ((backing_object = object->shadow) == VM_OBJECT_NULL)
return;
vm_object_lock(backing_object);
/*
* ...
* The backing object is not read_only,
* and no pages in the backing object are
* currently being paged out.
* The backing object is internal.
*
* XXX It may be sufficient for the backing
* XXX object to be temporary.
*/
if (!backing_object->internal ||
backing_object->paging_in_progress != 0) {
vm_object_unlock(backing_object);
return;
}
/*
* The backing object can't be a copy-object:
* the shadow_offset for the copy-object must stay
* as 0. Furthermore (for the 'we have all the
* pages' case), if we bypass backing_object and
* just shadow the next object in the chain, old
* pages from that object would then have to be copied
* BOTH into the (former) backing_object and into the
* parent object.
*/
if (backing_object->shadow != VM_OBJECT_NULL &&
backing_object->shadow->copy != VM_OBJECT_NULL) {
vm_object_unlock(backing_object);
return;
}
/*
* We know that we can either collapse the backing
* object (if the parent is the only reference to
* it) or (perhaps) remove the parent's reference
* to it.
*/
backing_offset = object->shadow_offset;
size = object->size;
/*
* If there is exactly one reference to the backing
* object, we can collapse it into the parent.
*/
if (backing_object->ref_count == 1) {
if (!vm_object_cache_lock_try()) {
vm_object_unlock(backing_object);
return;
}
/*
* We can collapse the backing object.
*
* Move all in-memory pages from backing_object
* to the parent. Pages that have been paged out
* will be overwritten by any of the parent's
* pages that shadow them.
*/
while (!queue_empty(&backing_object->memq)) {
p = (vm_page_t)
queue_first(&backing_object->memq);
new_offset = (p->offset - backing_offset);
assert(!p->busy || p->absent);
/*
* If the parent has a page here, or if
* this page falls outside the parent,
* dispose of it.
*
* Otherwise, move it as planned.
*/
if (p->offset < backing_offset ||
new_offset >= size) {
vm_page_lock_queues();
vm_page_free(p);
vm_page_unlock_queues();
} else {
pp = vm_page_lookup(object, new_offset);
if (pp != VM_PAGE_NULL && !pp->absent) {
/*
* Parent object has a real page.
* Throw away the backing object's
* page.
*/
vm_page_lock_queues();
vm_page_free(p);
vm_page_unlock_queues();
}
else {
if (pp != VM_PAGE_NULL) {
/*
* Parent has an absent page...
* it's not being paged in, so
* it must really be missing from
* the parent.
*
* Throw out the absent page...
* any faults looking for that
* page will restart with the new
* one.
*/
/*
* This should never happen -- the
* parent cannot have ever had an
* external memory object, and thus
* cannot have absent pages.
*/
panic("vm_object_collapse: bad case");
vm_page_lock_queues();
vm_page_free(pp);
vm_page_unlock_queues();
/*
* Fall through to move the backing
* object's page up.
*/
}
/*
* Parent now has no page.
* Move the backing object's page up.
*/
vm_page_rename(p, object, new_offset);
}
}
}
/*
* Move the pager from backing_object to object.
*
* XXX We're only using part of the paging space
* for keeps now... we ought to discard the
* unused portion.
*/
switch (vm_object_collapse_debug) {
case 0:
break;
case 1:
if ((backing_object->pager == IP_NULL) &&
(backing_object->pager_request ==
PAGER_REQUEST_NULL))
break;
/* Fall through to... */
default:
printf("vm_object_collapse: %#x (pager %#x, request %#x) up to %#x\n",
backing_object, backing_object->pager, backing_object->pager_request,
object);
if (vm_object_collapse_debug > 2)
Debugger("vm_object_collapse");
}
object->pager = backing_object->pager;
if (object->pager != IP_NULL)
ipc_kobject_set(object->pager,
(ipc_kobject_t) object,
IKOT_PAGER);
object->pager_initialized = backing_object->pager_initialized;
object->pager_ready = backing_object->pager_ready;
object->pager_created = backing_object->pager_created;
object->pager_request = backing_object->pager_request;
#if NORMA_VM
old_name_port = object->pager_name;
object->pager_name = backing_object->pager_name;
#else /* NORMA_VM */
if (object->pager_request != IP_NULL)
ipc_kobject_set(object->pager_request,
(ipc_kobject_t) object,
IKOT_PAGING_REQUEST);
old_name_port = object->pager_name;
if (old_name_port != IP_NULL)
ipc_kobject_set(old_name_port,
IKO_NULL, IKOT_NONE);
object->pager_name = backing_object->pager_name;
if (object->pager_name != IP_NULL)
ipc_kobject_set(object->pager_name,
(ipc_kobject_t) object,
IKOT_PAGING_NAME);
#endif /* NORMA_VM */
vm_object_cache_unlock();
/*
* If there is no pager, leave paging-offset alone.
*/
if (object->pager != IP_NULL)
object->paging_offset =
backing_object->paging_offset +
backing_offset;
#if MACH_PAGEMAP
assert(object->existence_info == VM_EXTERNAL_NULL);
object->existence_info = backing_object->existence_info;
#endif /* MACH_PAGEMAP */
/*
* Object now shadows whatever backing_object did.
* Note that the reference to backing_object->shadow
* moves from within backing_object to within object.
*/
object->shadow = backing_object->shadow;
object->shadow_offset += backing_object->shadow_offset;
if (object->shadow != VM_OBJECT_NULL &&
object->shadow->copy != VM_OBJECT_NULL) {
panic("vm_object_collapse: we collapsed a copy-object!");
}
/*
* Discard backing_object.
*
* Since the backing object has no pages, no
* pager left, and no object references within it,
* all that is necessary is to dispose of it.
*/
assert(
(backing_object->ref_count == 1) &&
(backing_object->resident_page_count == 0) &&
(backing_object->paging_in_progress == 0)
);
assert(backing_object->alive);
backing_object->alive = FALSE;
vm_object_unlock(backing_object);
vm_object_unlock(object);
if (old_name_port != IP_NULL)
#if NORMA_VM
ipc_port_release_send(old_name_port);
#else /* NORMA_VM */
ipc_port_dealloc_kernel(old_name_port);
#endif /* NORMA_VM */
zfree(vm_object_zone, (vm_offset_t) backing_object);
vm_object_lock(object);
object_collapses++;
}
else {
if (!vm_object_collapse_bypass_allowed) {
vm_object_unlock(backing_object);
return;
}
/*
* If all of the pages in the backing object are
* shadowed by the parent object, the parent
* object no longer has to shadow the backing
* object; it can shadow the next one in the
* chain.
*
* The backing object must not be paged out - we'd
* have to check all of the paged-out pages, as
* well.
*/
if (backing_object->pager_created) {
vm_object_unlock(backing_object);
return;
}
/*
* Should have a check for a 'small' number
* of pages here.
*/
queue_iterate(&backing_object->memq, p,
vm_page_t, listq)
{
new_offset = (p->offset - backing_offset);
/*
* If the parent has a page here, or if
* this page falls outside the parent,
* keep going.
*
* Otherwise, the backing_object must be
* left in the chain.
*/
if (p->offset >= backing_offset &&
new_offset <= size &&
(pp = vm_page_lookup(object, new_offset))
== VM_PAGE_NULL) {
/*
* Page still needed.
* Can't go any further.
*/
vm_object_unlock(backing_object);
return;
}
}
/*
* Make the parent shadow the next object
* in the chain. Deallocating backing_object
* will not remove it, since its reference
* count is at least 2.
*/
vm_object_reference(object->shadow = backing_object->shadow);
object->shadow_offset += backing_object->shadow_offset;
/*
* Backing object might have had a copy pointer
* to us. If it did, clear it.
*/
if (backing_object->copy == object)
backing_object->copy = VM_OBJECT_NULL;
/*
* Drop the reference count on backing_object.
* Since its ref_count was at least 2, it
* will not vanish; so we don't need to call
* vm_object_deallocate.
*/
backing_object->ref_count--;
assert(backing_object->ref_count > 0);
vm_object_unlock(backing_object);
object_bypasses ++;
}
/*
* Try again with this object's new backing object.
*/
}
}
/*
* Routine: vm_object_page_remove: [internal]
* Purpose:
* Removes all physical pages in the specified
* object range from the object's list of pages.
*
* In/out conditions:
* The object must be locked.
*/
unsigned int vm_object_page_remove_lookup = 0;
unsigned int vm_object_page_remove_iterate = 0;
void vm_object_page_remove(
register vm_object_t object,
register vm_offset_t start,
register vm_offset_t end)
{
register vm_page_t p, next;
/*
* One and two page removals are most popular.
* The factor of 16 here is somewhat arbitrary.
* It balances vm_object_lookup vs iteration.
*/
if (atop(end - start) < (unsigned)object->resident_page_count/16) {
vm_object_page_remove_lookup++;
for (; start < end; start += PAGE_SIZE) {
p = vm_page_lookup(object, start);
if (p != VM_PAGE_NULL) {
if (!p->fictitious)
pmap_page_protect(p->phys_addr,
VM_PROT_NONE);
vm_page_lock_queues();
vm_page_free(p);
vm_page_unlock_queues();
}
}
} else {
vm_object_page_remove_iterate++;
p = (vm_page_t) queue_first(&object->memq);
while (!queue_end(&object->memq, (queue_entry_t) p)) {
next = (vm_page_t) queue_next(&p->listq);
if ((start <= p->offset) && (p->offset < end)) {
if (!p->fictitious)
pmap_page_protect(p->phys_addr,
VM_PROT_NONE);
vm_page_lock_queues();
vm_page_free(p);
vm_page_unlock_queues();
}
p = next;
}
}
}
/*
* Routine: vm_object_coalesce
* Function: Coalesces two objects backing up adjoining
* regions of memory into a single object.
*
* returns TRUE if objects were combined.
*
* NOTE: Only works at the moment if the second object is NULL -
* if it's not, which object do we lock first?
*
* Parameters:
* prev_object First object to coalesce
* prev_offset Offset into prev_object
* next_object Second object into coalesce
* next_offset Offset into next_object
*
* prev_size Size of reference to prev_object
* next_size Size of reference to next_object
*
* Conditions:
* The object must *not* be locked.
*/
boolean_t vm_object_coalesce(
register vm_object_t prev_object,
vm_object_t next_object,
vm_offset_t prev_offset,
vm_offset_t next_offset,
vm_size_t prev_size,
vm_size_t next_size)
{
vm_size_t newsize;
#ifdef lint
next_offset++;
#endif /* lint */
if (next_object != VM_OBJECT_NULL) {
return FALSE;
}
if (prev_object == VM_OBJECT_NULL) {
return TRUE;
}
vm_object_lock(prev_object);
/*
* Try to collapse the object first
*/
vm_object_collapse(prev_object);
/*
* Can't coalesce if pages not mapped to
* prev_entry may be in use anyway:
* . more than one reference
* . paged out
* . shadows another object
* . has a copy elsewhere
* . paging references (pages might be in page-list)
*/
if ((prev_object->ref_count > 1) ||
prev_object->pager_created ||
(prev_object->shadow != VM_OBJECT_NULL) ||
(prev_object->copy != VM_OBJECT_NULL) ||
(prev_object->paging_in_progress != 0)) {
vm_object_unlock(prev_object);
return FALSE;
}
/*
* Remove any pages that may still be in the object from
* a previous deallocation.
*/
vm_object_page_remove(prev_object,
prev_offset + prev_size,
prev_offset + prev_size + next_size);
/*
* Extend the object if necessary.
*/
newsize = prev_offset + prev_size + next_size;
if (newsize > prev_object->size)
prev_object->size = newsize;
vm_object_unlock(prev_object);
return TRUE;
}
vm_object_t vm_object_request_object(
ipc_port_t p)
{
return vm_object_lookup(p);
}
/*
* Routine: vm_object_name
* Purpose:
* Returns a naked send right to the "name" port associated
* with this object.
*/
ipc_port_t vm_object_name(
vm_object_t object)
{
ipc_port_t p;
if (object == VM_OBJECT_NULL)
return IP_NULL;
vm_object_lock(object);
while (object->shadow != VM_OBJECT_NULL) {
vm_object_t new_object = object->shadow;
vm_object_lock(new_object);
vm_object_unlock(object);
object = new_object;
}
p = object->pager_name;
if (p != IP_NULL)
#if NORMA_VM
p = ipc_port_copy_send(p);
#else /* NORMA_VM */
p = ipc_port_make_send(p);
#endif /* NORMA_VM */
vm_object_unlock(object);
return p;
}
/*
* Attach a set of physical pages to an object, so that they can
* be mapped by mapping the object. Typically used to map IO memory.
*
* The mapping function and its private data are used to obtain the
* physical addresses for each page to be mapped.
*/
void
vm_object_page_map(
vm_object_t object,
vm_offset_t offset,
vm_size_t size,
vm_offset_t (*map_fn)(void *, vm_offset_t),
void * map_fn_data) /* private to map_fn */
{
int num_pages;
int i;
vm_page_t m;
vm_page_t old_page;
vm_offset_t addr;
num_pages = atop(size);
for (i = 0; i < num_pages; i++, offset += PAGE_SIZE) {
addr = (*map_fn)(map_fn_data, offset);
while ((m = vm_page_grab_fictitious()) == VM_PAGE_NULL)
vm_page_more_fictitious();
vm_object_lock(object);
if ((old_page = vm_page_lookup(object, offset))
!= VM_PAGE_NULL)
{
vm_page_lock_queues();
vm_page_free(old_page);
vm_page_unlock_queues();
}
vm_page_init(m, addr);
m->private = TRUE; /* don`t free page */
m->wire_count = 1;
vm_page_lock_queues();
vm_page_insert(m, object, offset);
vm_page_unlock_queues();
PAGE_WAKEUP_DONE(m);
vm_object_unlock(object);
}
}
#include <mach_kdb.h>
#if MACH_KDB
#define printf kdbprintf
boolean_t vm_object_print_pages = FALSE;
/*
* vm_object_print: [ debug ]
*/
void vm_object_print(
vm_object_t object)
{
register vm_page_t p;
extern indent;
register int count;
if (object == VM_OBJECT_NULL)
return;
iprintf("Object 0x%X: size=0x%X",
(vm_offset_t) object, (vm_offset_t) object->size);
printf(", %d references, %d resident pages,", object->ref_count,
object->resident_page_count);
printf(" %d absent pages,", object->absent_count);
printf(" %d paging ops\n", object->paging_in_progress);
indent += 2;
iprintf("memory object=0x%X (offset=0x%X),",
(vm_offset_t) object->pager, (vm_offset_t) object->paging_offset);
printf("control=0x%X, name=0x%X\n",
(vm_offset_t) object->pager_request, (vm_offset_t) object->pager_name);
iprintf("%s%s",
object->pager_ready ? " ready" : "",
object->pager_created ? " created" : "");
printf("%s,%s ",
object->pager_initialized ? "" : "uninitialized",
object->temporary ? "temporary" : "permanent");
printf("%s%s,",
object->internal ? "internal" : "external",
object->can_persist ? " cacheable" : "");
printf("copy_strategy=%d\n", (vm_offset_t)object->copy_strategy);
iprintf("shadow=0x%X (offset=0x%X),",
(vm_offset_t) object->shadow, (vm_offset_t) object->shadow_offset);
printf("copy=0x%X\n", (vm_offset_t) object->copy);
indent += 2;
if (vm_object_print_pages) {
count = 0;
p = (vm_page_t) queue_first(&object->memq);
while (!queue_end(&object->memq, (queue_entry_t) p)) {
if (count == 0) iprintf("memory:=");
else if (count == 4) {printf("\n"); iprintf(" ..."); count = 0;}
else printf(",");
count++;
printf("(off=0x%X,page=0x%X)", p->offset, (vm_offset_t) p);
p = (vm_page_t) queue_next(&p->listq);
}
if (count != 0)
printf("\n");
}
indent -= 4;
}
#endif /* MACH_KDB */
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