OpenGrok

/*	$NetBSD: uvm_object.c,v 1.26 2026/08/23 22:08:41 riastradh Exp $	*/

/*
 * Copyright (c) 2006, 2010, 2019 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Mindaugas Rasiukevicius.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. 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 FOUNDATION 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.
 */

/*
 * uvm_object.c: operate with memory objects
 *
 * TODO:
 *  1. Support PG_RELEASED-using objects
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: uvm_object.c,v 1.26 2026/08/23 22:08:41 riastradh Exp $");

#ifdef _KERNEL_OPT
#include "opt_ddb.h"
#endif

#include <sys/param.h>
#include <sys/rwlock.h>
#include <sys/queue.h>

#include <uvm/uvm.h>
#include <uvm/uvm_ddb.h>
#include <uvm/uvm_page_array.h>

/* Page count to fetch per single step. */
#define	FETCH_PAGECOUNT			16

/*
 * uvm_obj_init: initialize UVM memory object.
 */
void
uvm_obj_init(struct uvm_object *uo, const struct uvm_pagerops *ops,
    bool alock, u_int refs)
{

#if 0 /* notyet */
	KASSERT(ops);
#endif
	if (alock) {
		/* Allocate and assign a lock. */
		uo->vmobjlock = rw_obj_alloc();
	} else {
		/* The lock will need to be set via uvm_obj_setlock(). */
		uo->vmobjlock = NULL;
	}
	uo->pgops = ops;
	LIST_INIT(&uo->uo_ubc);
	uo->uo_npages = 0;
	uo->uo_refs = refs;
	radix_tree_init_tree(&uo->uo_pages);
}

/*
 * uvm_obj_destroy: destroy UVM memory object.
 */
void
uvm_obj_destroy(struct uvm_object *uo, bool dlock)
{

	KASSERT(radix_tree_empty_tree_p(&uo->uo_pages));

	/* Purge any UBC entries associated with this object. */
	ubc_purge(uo);

	/* Destroy the lock, if requested. */
	if (dlock) {
		rw_obj_free(uo->vmobjlock);
	}
	radix_tree_fini_tree(&uo->uo_pages);
}

/*
 * uvm_obj_setlock: assign a vmobjlock to the UVM object.
 *
 * => Caller is responsible to ensure that UVM objects is not use.
 * => Only dynamic lock may be previously set.  We drop the reference then.
 */
void
uvm_obj_setlock(struct uvm_object *uo, krwlock_t *lockptr)
{
	krwlock_t *olockptr = uo->vmobjlock;

	if (olockptr) {
		/* Drop the reference on the old lock. */
		rw_obj_free(olockptr);
	}
	if (lockptr == NULL) {
		/* If new lock is not passed - allocate default one. */
		lockptr = rw_obj_alloc();
	}
	uo->vmobjlock = lockptr;
}

/*
 * uvm_obj_wirepages: wire the pages of entire UVM object.
 *
 * => NOTE: this function should only be used for types of objects
 *  where PG_RELEASED flag is never set (aobj objects)
 * => caller must pass page-aligned start and end values
 */
int
uvm_obj_wirepages(struct uvm_object *uobj, off_t start, off_t end,
    struct pglist *list)
{
	int i, npages, error;
	struct vm_page *pgs[FETCH_PAGECOUNT], *pg = NULL;
	off_t offset = start, left;

	left = (end - start) >> PAGE_SHIFT;

	rw_enter(uobj->vmobjlock, RW_WRITER);
	while (left) {

		npages = MIN(FETCH_PAGECOUNT, left);

		/* Get the pages */
		memset(pgs, 0, sizeof(pgs));
		error = (*uobj->pgops->pgo_get)(uobj, offset, pgs, &npages, 0,
			VM_PROT_READ | VM_PROT_WRITE, UVM_ADV_SEQUENTIAL,
			PGO_SYNCIO);

		if (error)
			goto error;

		rw_enter(uobj->vmobjlock, RW_WRITER);
		for (i = 0; i < npages; i++) {

			KASSERT(pgs[i] != NULL);
			KASSERT(!(pgs[i]->flags & PG_RELEASED));

			/*
			 * Loan break
			 */
			if (pgs[i]->loan_count) {
				while (pgs[i]->loan_count) {
					uint64_t ticket =
					    uvm_wait_prepare();

					pg = uvm_loanbreak(pgs[i]);
					if (!pg) {
						rw_exit(uobj->vmobjlock);
						uvm_wait("uobjwirepg", ticket);
						rw_enter(uobj->vmobjlock,
						    RW_WRITER);
						continue;
					}
				}
				pgs[i] = pg;
			}

			if (pgs[i]->flags & PG_AOBJ) {
				uvm_pagemarkdirty(pgs[i],
				    UVM_PAGE_STATUS_DIRTY);
				uao_dropswap(uobj, i);
			}
		}

		/* Wire the pages */
		for (i = 0; i < npages; i++) {
			uvm_pagelock(pgs[i]);
			uvm_pagewire(pgs[i]);
			uvm_pageunlock(pgs[i]);
			if (list != NULL)
				TAILQ_INSERT_TAIL(list, pgs[i], pageq.queue);
		}

		/* Unbusy the pages */
		uvm_page_unbusy(pgs, npages);

		left -= npages;
		offset += npages << PAGE_SHIFT;
	}
	rw_exit(uobj->vmobjlock);

	return 0;

error:
	/* Unwire the pages which has been wired */
	uvm_obj_unwirepages(uobj, start, offset);

	return error;
}

/*
 * uvm_obj_unwirepages: unwire the pages of entire UVM object.
 *
 * => NOTE: this function should only be used for types of objects
 *  where PG_RELEASED flag is never set
 * => caller must pass page-aligned start and end values
 */
void
uvm_obj_unwirepages(struct uvm_object *uobj, off_t start, off_t end)
{
	struct vm_page *pg;
	off_t offset;

	rw_enter(uobj->vmobjlock, RW_WRITER);
	for (offset = start; offset < end; offset += PAGE_SIZE) {
		pg = uvm_pagelookup(uobj, offset);

		KASSERT(pg != NULL);
		KASSERT(!(pg->flags & PG_RELEASED));

		uvm_pagelock(pg);
		uvm_pageunwire(pg);
		uvm_pageunlock(pg);
	}
	rw_exit(uobj->vmobjlock);
}

static inline bool
uvm_obj_notag_p(struct uvm_object *uobj, int tag)
{

	KASSERT(rw_lock_held(uobj->vmobjlock));
	return radix_tree_empty_tagged_tree_p(&uobj->uo_pages, tag);
}

bool
uvm_obj_clean_p(struct uvm_object *uobj)
{

	return uvm_obj_notag_p(uobj, UVM_PAGE_DIRTY_TAG);
}

bool
uvm_obj_nowriteback_p(struct uvm_object *uobj)
{

	return uvm_obj_notag_p(uobj, UVM_PAGE_WRITEBACK_TAG);
}

static inline bool
uvm_obj_page_tag_p(struct vm_page *pg, int tag)
{
	struct uvm_object *uobj = pg->uobject;
	uint64_t pgidx = pg->offset >> PAGE_SHIFT;

	KASSERT(uobj != NULL);
	KASSERT(rw_lock_held(uobj->vmobjlock));
	return radix_tree_get_tag(&uobj->uo_pages, pgidx, tag) != 0;
}

static inline void
uvm_obj_page_set_tag(struct vm_page *pg, int tag)
{
	struct uvm_object *uobj = pg->uobject;
	uint64_t pgidx = pg->offset >> PAGE_SHIFT;

	KASSERT(uobj != NULL);
	KASSERT(rw_write_held(uobj->vmobjlock));
	radix_tree_set_tag(&uobj->uo_pages, pgidx, tag);
}

static inline void
uvm_obj_page_clear_tag(struct vm_page *pg, int tag)
{
	struct uvm_object *uobj = pg->uobject;
	uint64_t pgidx = pg->offset >> PAGE_SHIFT;

	KASSERT(uobj != NULL);
	KASSERT(rw_write_held(uobj->vmobjlock));
	radix_tree_clear_tag(&uobj->uo_pages, pgidx, tag);
}

bool
uvm_obj_page_dirty_p(struct vm_page *pg)
{

	return uvm_obj_page_tag_p(pg, UVM_PAGE_DIRTY_TAG);
}

void
uvm_obj_page_set_dirty(struct vm_page *pg)
{

	uvm_obj_page_set_tag(pg, UVM_PAGE_DIRTY_TAG);
}

void
uvm_obj_page_clear_dirty(struct vm_page *pg)
{

	uvm_obj_page_clear_tag(pg, UVM_PAGE_DIRTY_TAG);
}

bool
uvm_obj_page_writeback_p(struct vm_page *pg)
{

	return uvm_obj_page_tag_p(pg, UVM_PAGE_WRITEBACK_TAG);
}

void
uvm_obj_page_set_writeback(struct vm_page *pg)
{

	uvm_obj_page_set_tag(pg, UVM_PAGE_WRITEBACK_TAG);
}

void
uvm_obj_page_clear_writeback(struct vm_page *pg)
{

	uvm_obj_page_clear_tag(pg, UVM_PAGE_WRITEBACK_TAG);
}

#if defined(DDB) || defined(DEBUGPRINT)

/*
 * uvm_object_printit: actually prints the object
 */
void
uvm_object_printit(struct uvm_object *uobj, bool full,
    void (*pr)(const char *, ...))
{
	struct uvm_page_array a;
	struct vm_page *pg;
	int cnt = 0;
	voff_t off;

	(*pr)("OBJECT %p: locked=%d, pgops=%p, npages=%d, ",
	    uobj, rw_write_held(uobj->vmobjlock), uobj->pgops, uobj->uo_npages);
	if (UVM_OBJ_IS_KERN_OBJECT(uobj))
		(*pr)("refs=<SYSTEM>\n");
	else
		(*pr)("refs=%d\n", uobj->uo_refs);

	if (!full) {
		return;
	}
	(*pr)("  PAGES <pg,offset>:\n  ");
	uvm_page_array_init(&a, uobj, 0);
	off = 0;
	while ((pg = uvm_page_array_fill_and_peek(&a, off, 0)) != NULL) {
		cnt++;
		(*pr)("<%p,0x%llx> ", pg, (long long)pg->offset);
		if ((cnt % 3) == 0) {
			(*pr)("\n  ");
		}
		off = pg->offset + PAGE_SIZE;
		uvm_page_array_advance(&a);
	}
	if ((cnt % 3) != 0) {
		(*pr)("\n");
	}
	uvm_page_array_fini(&a);
}

#endif /* DDB || DEBUGPRINT */