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/*
* Copyright (c) 2023-2025 Ian Marco Moffett and the Osmora Team.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of Hyra 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 COPYRIGHT HOLDERS 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 COPYRIGHT OWNER 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.
*/
#include <sys/types.h>
#include <sys/param.h>
#include <sys/spinlock.h>
#include <sys/syslog.h>
#include <sys/errno.h>
#include <sys/param.h>
#include <vm/physmem.h>
#include <vm/vm_pager.h>
#include <vm/vm_page.h>
#include <vm/vm.h>
#define pr_trace(fmt, ...) kprintf("vm_anon: " fmt, ##__VA_ARGS__)
#define pr_error(...) pr_trace(__VA_ARGS__)
#define ANON_TIMEOUT_USEC 200000
/*
* Get pages from physical memory.
*
* @obp: Object representing the backing store (in memory).
* @pgs: Page descriptors to be filled.
* @off: Offset to read from in backing store.
* @len: Length to read in bytes.
*/
static int
anon_get(struct vm_object *obp, struct vm_page **pgs, off_t off, size_t len)
{
struct vm_page *pgtmp, *pgres;
int retval = 0;
size_t j, npgs;
len = ALIGN_DOWN(len, DEFAULT_PAGESIZE);
if (obp == NULL || pgs == NULL) {
return -EINVAL;
}
/* Zero bytes is invalid */
if (len == 0) {
len = 4096;
}
spinlock_acquire(&obp->lock);
npgs = len >> 12;
for (int i = 0; i < npgs; ++i) {
j = i / DEFAULT_PAGESIZE;
pgtmp = vm_pagelookup(obp, i);
pgres = pgs[j];
/* Do we need to create our own entry? */
if (pgtmp == NULL) {
pgtmp = vm_pagealloc(obp, PALLOC_ZERO);
}
if (pgtmp == NULL) {
pr_trace("anon_get: failed to add page %d, marking invalid\n", j);
pgres->flags &= ~PG_VALID;
continue;
}
*pgres = *pgtmp;
/*
* We are *just* populating `pgs' and therefore nobody
* should even attempt to acquire this lock... Shit
* happens though, so just make sure we can grab it
* without assuming success.
*/
if (spinlock_usleep(&pgres->lock, ANON_TIMEOUT_USEC) < 0) {
vm_pagefree(obp, pgtmp, 0);
pr_error("anon_get: pgres spin timeout\n");
return -ETIMEDOUT;
}
pgres->flags |= (PG_VALID | PG_CLEAN);
spinlock_release(&pgres->lock);
}
spinlock_release(&obp->lock);
return retval;
}
const struct vm_pagerops vm_anonops = {
.get = anon_get
};
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