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#include <arch/asm.h>

#include <mm/as.h>

#include <arch.h>

#include <arch/exception.h>

#include <config.h>

#include <print.h>

#include <symtab.h>

static phte_t *phte;

/** Try to find PTE for faulting address

 *

 * Try to find PTE for faulting address.

 * The AS->lock must be held on entry to this function.

 *

 * @param badvaddr Faulting virtual address.

 * @param istate Pointer to interrupted state.

 * @param pfrc Pointer to variable where as_page_fault() return code will be stored.

 * @return         PTE on success, NULL otherwise.

 *

 */

static pte_t *find_mapping_and_check(__address badvaddr, istate_t *istate, int *pfcr)

{

    /*

     * Check if the mapping exists in page tables.

     */

    pte_t *pte = page_mapping_find(AS, badvaddr);

    if ((pte) && (pte->p)) {

        /*

         * Mapping found in page tables.

         * Immediately succeed.

         */

        return pte;

    } else {

        int rc;

        /*

         * Mapping not found in page tables.

         * Resort to higher-level page fault handler.

         */

        page_table_unlock(AS, true);

        switch (rc = as_page_fault(badvaddr, istate)) {

            case AS_PF_OK:

                /*

                 * The higher-level page fault handler succeeded,

                 * The mapping ought to be in place.

                 */

                page_table_lock(AS, true);

                pte = page_mapping_find(AS, badvaddr);

                ASSERT((pte) && (pte->p));

                return pte;

            case AS_PF_DEFER:

                page_table_lock(AS, true);

                *pfcr = rc;

                return NULL;

            case AS_PF_FAULT:

                page_table_lock(AS, true);

                printf("Page fault.\n");

                *pfcr = rc;

                return NULL;

            default:

                panic("unexpected rc (%d)\n", rc);

        }  

    }

}

static void pht_refill_fail(__address badvaddr, istate_t *istate)

{

    char *symbol = "";

    char *sym2 = "";

    char *s = get_symtab_entry(istate->pc);

    if (s)

        symbol = s;

    s = get_symtab_entry(istate->lr);

    if (s)

        sym2 = s;

    panic("%p: PHT Refill Exception at %p (%s<-%s)\n", badvaddr, istate->pc, symbol, sym2);

}

static void pht_insert(const __address vaddr, const pfn_t pfn)

{

    __u32 page = (vaddr >> 12) & 0xffff;

    __u32 api = (vaddr >> 22) & 0x3f;

    __u32 vsid;

    asm volatile (

        "mfsrin %0, %1\n"

        : "=r" (vsid)

        : "r" (vaddr)

    );

    /* Primary hash (xor) */

    __u32 hash = ((vsid ^ page) & 0x3ff) << 3;

    __u32 i;

    /* Find unused PTE in PTEG */

    for (i = 0; i < 8; i++) {

        if (!phte[hash + i].v)

            break;

    }

    // TODO: Check access/change bits, secondary hash

    if (i == 8)

        i = page % 8;

    phte[hash + i].v = 1;

    phte[hash + i].vsid = vsid;

    phte[hash + i].h = 0;

    phte[hash + i].api = api;

    phte[hash + i].rpn = pfn;

    phte[hash + i].r = 0;

    phte[hash + i].c = 0;

    phte[hash + i].pp = 2; // FIXME

}

/** Process Instruction/Data Storage Interrupt

 *

 * @param data   True if Data Storage Interrupt.

 * @param istate Interrupted register context.

 *

 */

void pht_refill(bool data, istate_t *istate)

{

    asid_t asid;

    __address badvaddr;

    pte_t *pte;

    int pfcr;

    if (data) {

        asm volatile (

            "mfdar %0\n"

            : "=r" (badvaddr)

        );

    } else

        badvaddr = istate->pc;

    spinlock_lock(&AS->lock);

    asid = AS->asid;

    spinlock_unlock(&AS->lock);

    page_table_lock(AS, true);

    pte = find_mapping_and_check(badvaddr, istate, &pfcr);

    if (!pte) {

        switch (pfcr) {

        case AS_PF_FAULT:

            goto fail;

            break;

        case AS_PF_DEFER:

            /*

             * The page fault came during copy_from_uspace()

             * or copy_to_uspace().

             */

            page_table_unlock(AS, true);

            return;

        default:

            panic("Unexpected pfrc (%d)\n", pfcr);

            break;

        }

    }

    pte->a = 1; /* Record access to PTE */

    pht_insert(badvaddr, pte->pfn);

    page_table_unlock(AS, true);

    return;

fail:

    page_table_unlock(AS, true);

    pht_refill_fail(badvaddr, istate);

}

void pht_init(void)

{

    memsetb((__address) phte, 1 << PHT_BITS, 0);

    /* Insert global kernel mapping */

    __address cur;

    for (cur = 0; cur < last_frame; cur += FRAME_SIZE) {

        pte_t *pte = page_mapping_find(AS_KERNEL, PA2KA(cur));

        if ((pte) && (pte->p) && (pte->g))

            pht_insert(PA2KA(cur), pte->pfn);

    }

}

    if (config.cpu_active == 1) {

        /*

         * PA2KA(identity) mapping for all frames until last_frame.

         */

        __address cur;

        int flags;

        for (cur = 0; cur < last_frame; cur += FRAME_SIZE) {

            flags = PAGE_CACHEABLE;

            if ((PA2KA(cur) >= config.base) && (PA2KA(cur) < config.base + config.kernel_size))

                flags |= PAGE_GLOBAL;

            page_mapping_insert(AS_KERNEL, PA2KA(cur), cur, flags);

        }

        /* Allocate page hash table */

        phte_t *physical_phte = (phte_t *) PFN2ADDR(frame_alloc(PHT_ORDER, FRAME_KA | FRAME_PANIC));

        phte = (phte_t *) PA2KA((__address) physical_phte);

        ASSERT((__address) physical_phte % (1 << PHT_BITS) == 0);

        pht_init();

        asm volatile (

            "mtsdr1 %0\n"

            :

            : "r" ((__address) physical_phte)

        );

        /* Invalidate block address translation registers,

           thus remove the temporary mapping */

//      invalidate_bat();

    }