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/*
* Copyright (c) 2023 Ian Marco Moffett and the VegaOS 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 VegaOS 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/cdefs.h>
#include <sys/panic.h>
#include <vm/vm_page.h>
#include <vm/vm.h>
#include <string.h>
__MODULE_NAME("vm_page");
__KERNEL_META("$Vega$: vm_page.c, Ian Marco Moffett, "
"Virtual memory page specific operations");
/*
* Zero `page_count' pages.
*
* @page: First page to start zeroing at
* @page_count: Number of pages to zero.
*/
void
vm_zero_page(void *page, size_t page_count)
{
const size_t PAGE_SIZE = vm_get_page_size();
size_t bytes = page_count * PAGE_SIZE;
/*
* This *should not* happen. Page sizes
* are usually 2^n but if this runs, something
* *very* weird is happening and either something
* broke badly. Or it's that damn technological
* degeneration that is getting out of hand within
* our world!! But really, page sizes *should* be a
* power of 2 and it would be pretty worrying if
* this branches causing a panic stating something
* that shouldn't happen, happened.
*
* The reason why it is wise for pages to be a power of
* 2 is so we can efficiently read/write to the page in
* fixed-sized power of 2 blocks cleanly without the risk
* of clobbering other pages we didn't intend to mess with.
*/
if ((PAGE_SIZE & 1) != 0) {
panic("Unexpected page size, not power of 2!\n");
}
memset64(page, 0, bytes/8);
}
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