os-k/kaleid/kernel/mm/paging.c

#include <kernel.h>

#define PAGESIZE (4 * KB)


// Page directory pointer offset
typedef ulong    pdpe_t;

// Page directory offset
typedef ulong    pde_t;

// Page table entry
typedef ulong    pte_t;

// paging.asm
void MmLoadPML4(void *);
void MmEnableWriteProtect(void);
void MmDisableWriteProtect(void);

enum
{
    MF_PRESENT      = 1 << 0,
    MF_READWRITE    = 1 << 1,
    MF_USERMODE     = 1 << 2,
    MF_WRITETHR     = 1 << 3,
    MF_CACHEDIS     = 1 << 4,
    MF_ACCESSED     = 1 << 5,
    MF_DIRTY        = 1 << 6
};

#define RAM 8

//-----------

volatile pdpe_t PML4[512] __attribute__((__aligned__(4096)));

// First PDPE of our pml4
volatile pde_t PDP[512] __attribute__((__aligned__(4096)));

// First PDP of first_pdpe
volatile pte_t PD[512 * RAM] __attribute__((__aligned__(4096)));


void MmInitPaging(void)
{
    memzero((void *)&PML4[0], sizeof(PML4));
    memzero((void *)&PDP[0], sizeof(PDP));
    memzero((void *)&PD[0], sizeof(PD));

    for (int i = 0; i < 512 * RAM; i++) {
        PD[i] = ((ulong)i * 2048 * 1024) | MF_PRESENT | MF_READWRITE | 1 << 7;
    }

    for (int i = 0; i < RAM; i++) {
        PDP[i] = (ulong)(&PD[i*512])| MF_PRESENT | MF_READWRITE;
    }

    PML4[0] = (ulong)(&PDP[0])| MF_PRESENT | MF_READWRITE;

    MmLoadPML4((void *)PML4);
}