banan-os/kernel/arch/i386/Paging.cpp

66 lines
1.6 KiB
C++

#include <kernel/Paging.h>
#include <kernel/panic.h>
namespace Paging
{
static uint32_t s_page_directory[1024] __attribute__((aligned(4096)));
static uint32_t s_page_table[1024] __attribute__((aligned(4096)));
static uint32_t s_page_table_framebuffer[1024] __attribute__((aligned(4096)));
static uint32_t s_page_table_rsdp[1024] __attribute__((aligned(4096)));
static uint32_t s_page_table_apic[1024] __attribute__((aligned(4096)));
void Initialize()
{
for (uint32_t i = 0; i < 1024; i++)
s_page_directory[i] = 0x00000002;
for (uint32_t i = 0; i < 1024; i++)
s_page_table[i] = (i << 12) | 0x03;
s_page_directory[0] = (uint32_t)s_page_table | 0x03;
asm volatile(
"movl %%eax, %%cr3;"
"movl %%cr0, %%eax;"
"orl $0x80000001, %%eax;"
"movl %%eax, %%cr0;"
:: "a"(s_page_directory)
);
}
static void MapPDE(uint32_t address, uint32_t* pt)
{
if ((address & 0xffc00000) != address)
Kernel::panic("Trying to map non 4 MiB aligned address");
uint32_t pd_index = address >> 22;
if (!(s_page_directory[pd_index] & (1 << 0)))
{
// Identity map the whole page table
for (uint32_t i = 0; i < 1024; i++)
pt[i] = address | (i << 12) | 0x03;
// Set the pde to point to page table
s_page_directory[pd_index] = (uint32_t)pt | 0x03;
// Flush TLB
for (uint32_t i = 0; i < 1024; i++)
asm volatile("invlpg (%0)" :: "r" (address | (i << 12)) : "memory");
}
}
void MapFramebuffer(uint32_t address)
{
MapPDE(address, s_page_table_framebuffer);
}
void MapRSDP(uint32_t address)
{
MapPDE(address, s_page_table_rsdp);
}
void MapAPIC(uint32_t address)
{
MapPDE(address, s_page_table_apic);
}
}