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/* Definitions for identic page mapper */

pte_t helper_ptl1[512] __attribute__((aligned (PAGE_SIZE)));

pte_t helper_ptl2[512] __attribute__((aligned (PAGE_SIZE)));

pte_t helper_ptl3[512] __attribute__((aligned (PAGE_SIZE)));

extern pte_t ptl_0; /* From boot.S */

#define PTL1_PRESENT(ptl0, page) (!(GET_PTL1_FLAGS_ARCH(ptl0, PTL0_INDEX_ARCH(page)) & PAGE_NOT_PRESENT))

#define PTL2_PRESENT(ptl1, page) (!(GET_PTL2_FLAGS_ARCH(ptl1, PTL1_INDEX_ARCH(page)) & PAGE_NOT_PRESENT))

#define PTL3_PRESENT(ptl2, page) (!(GET_PTL3_FLAGS_ARCH(ptl2, PTL2_INDEX_ARCH(page)) & PAGE_NOT_PRESENT))

#define PTL1_ADDR(ptl0, page) ((pte_t *)PA2KA(GET_PTL1_ADDRESS_ARCH(ptl0, PTL0_INDEX_ARCH(page))))

#define PTL2_ADDR(ptl1, page) ((pte_t *)PA2KA(GET_PTL2_ADDRESS_ARCH(ptl1, PTL1_INDEX_ARCH(page))))

#define PTL3_ADDR(ptl2, page) ((pte_t *)PA2KA(GET_PTL3_ADDRESS_ARCH(ptl2, PTL2_INDEX_ARCH(page))))

#define SETUP_PTL1(ptl0, page, tgt)  {  \

    SET_PTL1_ADDRESS_ARCH(ptl0, PTL0_INDEX_ARCH(page), (__address)KA2PA(tgt)); \

        SET_PTL1_FLAGS_ARCH(ptl0, PTL0_INDEX_ARCH(page), PAGE_WRITE | PAGE_EXEC); \

    }

#define SETUP_PTL2(ptl1, page, tgt)  {  \

    SET_PTL2_ADDRESS_ARCH(ptl1, PTL1_INDEX_ARCH(page), (__address)KA2PA(tgt)); \

        SET_PTL2_FLAGS_ARCH(ptl1, PTL1_INDEX_ARCH(page), PAGE_WRITE | PAGE_EXEC); \

    }

#define SETUP_PTL3(ptl2, page, tgt)  {  \

    SET_PTL3_ADDRESS_ARCH(ptl2, PTL2_INDEX_ARCH(page), (__address)KA2PA(tgt)); \

        SET_PTL3_FLAGS_ARCH(ptl2, PTL2_INDEX_ARCH(page), PAGE_WRITE | PAGE_EXEC); \

    }

#define SETUP_FRAME(ptl3, page, tgt)  { \

    SET_FRAME_ADDRESS_ARCH(ptl3, PTL3_INDEX_ARCH(page), (__address)KA2PA(tgt)); \

        SET_FRAME_FLAGS_ARCH(ptl3, PTL3_INDEX_ARCH(page), PAGE_WRITE | PAGE_EXEC); \

    }

/** Identic page mapper

 *

 * We need to map whole physical memory identically before the page subsystem

 * is initializaed. This thing clears page table and fills in the specific

 * items.

 */

void ident_page_fault(int n, istate_t *istate)

{

    __address page;

    static __address oldpage = 0;

    pte_t *aptl_1, *aptl_2, *aptl_3;

    page = read_cr2();

    if (oldpage) {

        /* Unmap old address */

        aptl_1 = PTL1_ADDR(&ptl_0, oldpage);

        aptl_2 = PTL2_ADDR(aptl_1, oldpage);

        aptl_3 = PTL3_ADDR(aptl_2, oldpage);

        SET_FRAME_FLAGS_ARCH(aptl_3, PTL3_INDEX_ARCH(oldpage), PAGE_NOT_PRESENT);

        if (aptl_3 == helper_ptl3)

            SET_PTL3_FLAGS_ARCH(aptl_2, PTL2_INDEX_ARCH(oldpage), PAGE_NOT_PRESENT);

        if (aptl_2 == helper_ptl2)

            SET_PTL2_FLAGS_ARCH(aptl_1, PTL1_INDEX_ARCH(oldpage), PAGE_NOT_PRESENT);

        if (aptl_1 == helper_ptl1)

            SET_PTL1_FLAGS_ARCH(&ptl_0, PTL0_INDEX_ARCH(oldpage), PAGE_NOT_PRESENT);

    }

    if (PTL1_PRESENT(&ptl_0, page))

        aptl_1 = PTL1_ADDR(&ptl_0, page);

    else {

        SETUP_PTL1(&ptl_0, page, helper_ptl1);

        aptl_1 = helper_ptl1;

    }

    if (PTL2_PRESENT(aptl_1, page))

        aptl_2 = PTL2_ADDR(aptl_1, page);

    else {

        SETUP_PTL2(aptl_1, page, helper_ptl2);

        aptl_2 = helper_ptl2;

    }

    if (PTL3_PRESENT(aptl_2, page))

        aptl_3 = PTL3_ADDR(aptl_2, page);

    else {

        SETUP_PTL3(aptl_2, page, helper_ptl3);

        aptl_3 = helper_ptl3;

    }

    SETUP_FRAME(aptl_3, page, page);

    oldpage = page;

}