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#include "loader_efi.h"
#include <kernel/memory/paging.h>
#define KERNEL_SPACE_LOWER (void *)0xffffffff80000000
#define KERNEL_SPACE_UPPER (void *)0xffffffffc0000000
static uint64_t *new_page_table(void);
static uint64_t *get_page_table(void *vaddr, int level);
static uint64_t *get_page_entry(void *vaddr);
static uint64_t *get_page_map(void);
static void set_page_map(uint64_t *map);
static uint64_t *efi_page_map = NULL;
static uint64_t *system_page_map = NULL;
void paging_init(void)
{
efi_page_map = get_page_map();
system_page_map = new_page_table();
if (!system_page_map)
{
Print(L"error creating page map: %r\r\n", e_last_error);
efi_exit(e_last_error);
}
// copy the identity mappings from the EFI PML4.
system_page_map[0] = efi_page_map[0];
// create kernel fractal mappings
// TODO: move this into the kernel instead?
uint64_t *lower_pm2 = get_page_table(KERNEL_SPACE_LOWER, 2);
uint64_t *upper_pm2 = get_page_table(KERNEL_SPACE_UPPER, 2);
upper_pm2[PAGE_TABLE_INDEX_MASK - 1] = (phys_addr_t)lower_pm2|DATA_PAGE_TYPE;
upper_pm2[PAGE_TABLE_INDEX_MASK] = (phys_addr_t)upper_pm2|DATA_PAGE_TYPE;
}
void paging_enter(void)
{
// use the system_page_map instead of efi_page_map
set_page_map(system_page_map);
}
void *paging_map_page(void *vaddr, phys_addr_t paddr, enum page_type type)
{
uint64_t *entry = get_page_entry(vaddr);
if (entry)
{
*entry = paddr | type;
return vaddr;
}
return NULL;
}
void *paging_map_pages(void *vaddr,
phys_addr_t paddr,
enum page_type type,
size_t size)
{
for (size_t offset = 0; offset < size; offset += page_size(1))
{
if (!paging_map_page((char *)vaddr + offset, paddr + offset, type))
{
return NULL;
}
}
return vaddr;
}
void *paging_map_range(void *vaddr,
struct memory_range *range,
enum page_type type)
{
return paging_map_pages(vaddr, range->base, type, range->size);
}
static uint64_t *new_page_table(void)
{
struct memory_range table = system_allocate(page_size(1));
if (table.type == SYSTEM_MEMORY)
{
e_bs->SetMem((void *)table.base, table.size, 0);
return (uint64_t *)table.base;
}
return NULL;
}
static uint64_t *get_page_table(void *vaddr, int level)
{
// don't try to do anything if there's no page map.
if (!system_page_map)
{
return NULL;
}
// don't try to do anything outside of the page map
if ((level < 1) || (level > PAGE_MAP_LEVELS))
{
return NULL;
}
// don't use a non-canonical address
uint64_t *map = system_page_map;
for (int i = PAGE_MAP_LEVELS; i > level; i--)
{
if (!map[pte_index(vaddr, i)])
{
uint64_t *next_map = new_page_table();
map[pte_index(vaddr, i)] = (phys_addr_t)next_map|PAGE_PR|PAGE_WR;
map = next_map;
}
else
{
map = (uint64_t *)page_address(map[pte_index(vaddr, i)], 1);
}
}
return map;
}
static uint64_t *get_page_entry(void *vaddr)
{
uint64_t *table = get_page_table(vaddr, 1);
return &table[pte_index(vaddr, 1)];
}
static uint64_t *get_page_map(void)
{
uint64_t map;
__asm__("mov %%cr3, %0" : "=r"(map));
return (uint64_t *)(page_address(map, 1));
}
static void set_page_map(uint64_t *map)
{
__asm__
(
"pushf\r\n"
"cli\r\n"
"mov %0, %%cr3\r\n"
"popf"
:
: "r"(map)
);
}
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