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/*
* Copyright (c) 2023-2024 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/param.h>
#include <sys/types.h>
#include <sys/limine.h>
#include <sys/syslog.h>
#include <sys/spinlock.h>
#include <vm/physmem.h>
#include <vm/vm.h>
#include <string.h>
size_t highest_frame_idx = 0;
size_t bitmap_size = 0;
size_t bitmap_free_start = 0;
uint8_t *bitmap;
static struct limine_memmap_response *resp = NULL;
static struct spinlock lock = {0};
static struct limine_memmap_request mmap_req = {
.id = LIMINE_MEMMAP_REQUEST,
.revision = 0
};
/*
* Populate physical memory bitmap.
*/
static void
physmem_populate_bitmap(void)
{
struct limine_memmap_entry *ent;
for (size_t i = 0; i < resp->entry_count; ++i) {
ent = resp->entries[i];
if (ent->type != LIMINE_MEMMAP_USABLE) {
/* This memory is not usable */
continue;
}
if (bitmap_free_start == 0) {
bitmap_free_start = ent->base / DEFAULT_PAGESIZE;
}
for (size_t j = 0; j < ent->length; j += DEFAULT_PAGESIZE) {
clrbit(bitmap, (ent->base + j) / DEFAULT_PAGESIZE);
}
}
}
/*
* Allocate physical memory for the bitmap
* we'll use to keep track of free memory.
*/
static void
physmem_alloc_bitmap(void)
{
struct limine_memmap_entry *ent;
uintptr_t highest_addr = 0;
for (size_t i = 0; i < resp->entry_count; ++i) {
ent = resp->entries[i];
if (ent->type != LIMINE_MEMMAP_USABLE) {
/* This memory is not usable */
continue;
}
if (ent->length >= bitmap_size) {
bitmap = PHYS_TO_VIRT(ent->base);
memset(bitmap, 0xFF, bitmap_size);
ent->length -= bitmap_size;
ent->base += bitmap_size;
return;
}
highest_addr = MAX(highest_addr, ent->base + ent->length);
}
}
/*
* Init the physical memory bitmap.
*/
static void
physmem_init_bitmap(void)
{
uintptr_t highest_addr = 0;
struct limine_memmap_entry *ent;
for (size_t i = 0; i < resp->entry_count; ++i) {
ent = resp->entries[i];
if (ent->type != LIMINE_MEMMAP_USABLE) {
continue;
}
highest_addr = MAX(highest_addr, ent->base + ent->length);
}
highest_frame_idx = highest_addr / DEFAULT_PAGESIZE;
bitmap_size = ALIGN_UP(highest_frame_idx / 8, DEFAULT_PAGESIZE);
physmem_alloc_bitmap();
physmem_populate_bitmap();
}
/*
* Allocate page frames.
*
* @count: Number of frames to allocate.
*/
uintptr_t
vm_alloc_frame(size_t count)
{
size_t frames = 0;
uintptr_t ret = 0;
spinlock_acquire(&lock);
for (size_t i = 0; i < highest_frame_idx; ++i) {
if (!testbit(bitmap, i)) {
/* We have a free page */
if (++frames != count) {
continue;
}
for (size_t j = i; j < i + count; ++j) {
setbit(bitmap, j);
}
ret = i * DEFAULT_PAGESIZE;
break;
}
}
spinlock_release(&lock);
return ret;
}
void
vm_free_frame(uintptr_t base, size_t count)
{
size_t stop_at = base + (count * DEFAULT_PAGESIZE);
spinlock_acquire(&lock);
for (uintptr_t p = base; p < stop_at; p += DEFAULT_PAGESIZE) {
clrbit(bitmap, p / DEFAULT_PAGESIZE);
}
spinlock_release(&lock);
}
void
vm_physmem_init(void)
{
resp = mmap_req.response;
physmem_init_bitmap();
}
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