mango/sandbox/vm/page.c

#include <socks/types.h>
#include <socks/memblock.h>
#include <socks/vm.h>
#include <string.h>
#include <stdio.h>

/* array of pages, one for each physical page frame present in RAM */
static vm_page_t *page_array = NULL;

/* number of pages stored in page_array */
static size_t page_array_count = 0;

/* Pre-calculated page order -> size conversion table */
static size_t page_order_bytes[] = {
	[VM_PAGE_4K]   = 0x1000,
	[VM_PAGE_8K]   = 0x2000,
	[VM_PAGE_16K]  = 0x4000,
	[VM_PAGE_32K]  = 0x8000,
	[VM_PAGE_64K]  = 0x10000,
	[VM_PAGE_128K] = 0x20000,
	[VM_PAGE_256K] = 0x40000,
	[VM_PAGE_512K] = 0x80000,
	[VM_PAGE_1M]   = 0x100000,
	[VM_PAGE_2M]   = 0x200000,
	[VM_PAGE_4M]   = 0x400000,
	[VM_PAGE_8M]   = 0x800000,
	[VM_PAGE_16M]  = 0x1000000,
	[VM_PAGE_32M]  = 0x2000000,
	[VM_PAGE_64M]  = 0x4000000,
	[VM_PAGE_128M] = 0x8000000,
	[VM_PAGE_256M] = 0x10000000,
	[VM_PAGE_512M] = 0x20000000,
	[VM_PAGE_1G]   = 0x40000000,
};

void vm_page_init_array()
{
	size_t pmem_size = 0;

	memblock_iter_t it;
	for_each_mem_range (&it, 0x0, UINTPTR_MAX) {
		if (pmem_size < it.it_limit + 1) {
			pmem_size = it.it_limit + 1;
		}
	}

	size_t nr_pages = pmem_size / VM_PAGE_SIZE;
	if (pmem_size % VM_PAGE_SIZE) {
		nr_pages++;
	}

	page_array = memblock_alloc(sizeof(vm_page_t) * nr_pages);
	page_array_count = nr_pages;
	printf("page_array covers 0x%zx bytes, %zu page frames\n", pmem_size, pmem_size / VM_PAGE_SIZE);
	printf("page_array is %zu bytes long\n", sizeof(vm_page_t) * nr_pages);

	for (size_t i = 0; i < nr_pages; i++) {
		memset(&page_array[i], 0x0, sizeof page_array[i]);
	}

	size_t nr_reserved = 0;
	for_each_reserved_mem_range(&it, 0x0, UINTPTR_MAX) {
		for (uintptr_t i = it.it_base; i < it.it_limit; i += VM_PAGE_SIZE) {
			size_t pfn = i / VM_PAGE_SIZE;

			page_array[pfn].p_flags |= VM_PAGE_RESERVED;
			nr_reserved++;
		}
	}

	printf("%zu reserved page frames\n", nr_reserved);
}

vm_page_t *vm_page_get(phys_addr_t addr)
{
	size_t pfn = addr / VM_PAGE_SIZE;
	return pfn < page_array_count ? &page_array[pfn] : NULL;
}

phys_addr_t vm_page_get_paddr(vm_page_t *pg)
{
	return vm_page_get_pfn(pg) * VM_PAGE_SIZE;
}

void *vm_page_get_vaddr(vm_page_t *pg)
{
	/* TODO */
	return NULL;
}

size_t vm_page_get_pfn(vm_page_t *pg)
{
	return ((uintptr_t)pg - (uintptr_t)page_array) / sizeof *pg;
}

size_t vm_page_order_to_bytes(vm_page_order_t order)
{
	if (order < 0 || order > VM_PAGE_MAX_ORDER) {
		return 0;
	}

	return page_order_bytes[order];
}

phys_addr_t vm_page_order_to_pages(vm_page_order_t order)
{
	if (order < 0 || order > VM_PAGE_MAX_ORDER) {
		return 0;
	}

	return page_order_bytes[order] >> VM_PAGE_SHIFT;
}

vm_alignment_t vm_page_order_to_alignment(vm_page_order_t order)
{
	if (order < 0 || order > VM_PAGE_MAX_ORDER) {
		return 0;
	}

	return ~(page_order_bytes[order] - 1);
}


size_t vm_bytes_to_pages(size_t bytes)
{
	if (bytes & (VM_PAGE_SIZE-1)) {
		bytes &= ~(VM_PAGE_SIZE-1);
		bytes += VM_PAGE_SIZE;
	}

	bytes >>= VM_PAGE_SHIFT;
	return bytes;
}

vm_zone_t *vm_page_get_zone(vm_page_t *pg)
{
	vm_pg_data_t *node = vm_pg_data_get(pg->p_node);
	if (!node) {
		return 0;
	}

	if (pg->p_zone >= VM_MAX_ZONES) {
		return NULL;
	}
	
	return &node->pg_zones[pg->p_zone];
}


vm_page_t *vm_page_alloc(vm_page_order_t order, vm_flags_t flags)
{
	/* TODO prefer nodes closer to us */
	vm_pg_data_t *node = vm_pg_data_get(0);
	vm_zone_id_t zone_id = VM_ZONE_HIGHMEM;
	if (flags & VM_GET_DMA) {
		zone_id = VM_ZONE_DMA;
	}

	while (1) {
		vm_zone_t *z = &node->pg_zones[zone_id];

		vm_page_t *pg = vm_zone_alloc_page(z, order, flags);
		if (pg) {
			return pg;
		}

		if (zone_id == VM_ZONE_MIN) {
			break;
		}

		zone_id--;
	}
	
	return NULL;
}

void vm_page_free(vm_page_t *pg)
{
	vm_zone_t *z = vm_page_get_zone(pg);
	if (!z) {
		return;
	}

	vm_zone_free_page(z, pg);
}

int vm_page_split(vm_page_t *pg, vm_page_t **a, vm_page_t **b)
{
	if (pg->p_order == VM_PAGE_MIN_ORDER) {
		return -1;
	}

	size_t nr_frames = vm_page_order_to_pages(pg->p_order);
	for (size_t i = 0; i < nr_frames; i++) {
		pg[i].p_order = pg->p_order - 1;
	}

	vm_page_t *buddy = vm_page_get_buddy(pg);

	if (pg->p_order == VM_PAGE_MIN_ORDER) {
		pg->p_flags &= ~(VM_PAGE_HUGE | VM_PAGE_HEAD);
		buddy->p_flags &= ~(VM_PAGE_HUGE | VM_PAGE_HEAD);
	} else {
		pg->p_flags |= VM_PAGE_HEAD | VM_PAGE_HUGE;
		buddy->p_flags |= VM_PAGE_HEAD | VM_PAGE_HUGE;
	}

	*a = pg;
	*b = buddy;
	
	return 0;
}

vm_page_t *vm_page_merge(vm_page_t *a, vm_page_t *b)
{
	if (a->p_order != b->p_order) {
		return NULL;
	}

	if (a->p_order == VM_PAGE_MAX_ORDER) {
		return NULL;
	}

	if (vm_page_get_buddy(a) != b) {
		return NULL;
	}
	
	if (VM_PAGE_IS_RESERVED(a) && !VM_PAGE_IS_RESERVED(b)) {
		return NULL;
	}

	if (!VM_PAGE_IS_RESERVED(a) && VM_PAGE_IS_RESERVED(b)) {
		return NULL;
	}

	/* make sure that a comes before b */
	if (a > b) {
		vm_page_t *tmp = a;
		a = b;
		b = tmp;
	}

	a->p_order++;

	size_t nr_frames = vm_page_order_to_pages(a->p_order);
	for (size_t i = 0; i < nr_frames; i++) {
		a[i].p_flags &= ~VM_PAGE_HEAD;
		a[i].p_flags |= VM_PAGE_HUGE;
		a[i].p_order = a->p_order;
	}

	a->p_flags |= VM_PAGE_HEAD;
	
	return 0;
}

vm_page_t *vm_page_get_buddy(vm_page_t *pg)
{
	phys_addr_t paddr = vm_page_get_paddr(pg);
	paddr = paddr ^ vm_page_order_to_bytes(pg->p_order);
	return vm_page_get(paddr);
}

vm_page_t *vm_page_get_next_tail(vm_page_t *pg)
{
	vm_page_t *next = pg + 1;
	if (next->p_flags & VM_PAGE_HEAD || !(next->p_flags & VM_PAGE_HUGE)) {
		return NULL;
	}

	return next;
}