/*      $NetBSD: uvm_object.c,v 1.25 2020/08/15 07:24:09 chs 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 1.25 2020/08/15 07:24:09 chs 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) {
                                       pg = uvm_loanbreak(pgs[i]);
                                       if (!pg) {
                                               rw_exit(uobj->vmobjlock);
                                               uvm_wait("uobjwirepg");
                                               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 */

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