///////////////////////////////////////////////////////////////////////////////////
// File     : vm_handler.c
// Date     : 01/07/2012
// Author   : alain greiner
// Copyright (c) UPMC-LIP6
///////////////////////////////////////////////////////////////////////////////////
// The vm_handler.c and vm_handler.h files are part ot the GIET nano kernel.
// They contains the kernel data structures and functions used to dynamically
// handle the iommu page table.
// 
// TODO : We must transfer here the functions used to statically build
// the page tables associated to the various vspaces (now in boot_handler.c)
// 
///////////////////////////////////////////////////////////////////////////////////

#include <vm_handler.h>
#include <sys_handler.h>
#include <common.h>
#include <giet_config.h>

/////////////////////////////////////////////////////////////////////////////
//     Global variable : IOMMU page table
/////////////////////////////////////////////////////////////////////////////

__attribute__((section (".iommu"))) page_table_t _iommu_ptab;

//////////////////////////////////////////////////////////////////////////////
// _iommu_add_pte2()
//////////////////////////////////////////////////////////////////////////////
void _iommu_add_pte2(
        unsigned int ix1,
        unsigned int ix2,
        unsigned int ppn,
        unsigned int flags) {
    unsigned int ptba;
    unsigned int * pt_ppn;
    unsigned int * pt_flags;

    // get pointer on iommu page table
    page_table_t * pt = &_iommu_ptab;

    // get ptba and update PT2
    if ((pt->pt1[ix1] & PTE_V) == 0) {
        _puts("\n[GIET ERROR] in iommu_add_pte2 function\n");
        _puts("the IOMMU PT1 entry is not mapped / ix1 = ");
        _putx( ix1 );
        _puts("\n");
        _exit();
    }
    else {
        ptba = pt->pt1[ix1] << 12;
        pt_flags = (unsigned int *) (ptba + 8 * ix2);
        pt_ppn = (unsigned int *) (ptba + 8 * ix2 + 4);
        *pt_flags = flags;
        *pt_ppn = ppn;
    }
} // end _iommu_add_pte2()


//////////////////////////////////////////////////////////////////////////////
// _iommu_inval_pte2()
//////////////////////////////////////////////////////////////////////////////
void _iommu_inval_pte2(unsigned int ix1, unsigned int ix2) {
    unsigned int ptba;
    unsigned int * pt_flags;

    // get pointer on iommu page table
    page_table_t * pt = &_iommu_ptab;

    // get ptba and inval PTE2
    if ((pt->pt1[ix1] & PTE_V) == 0) {
        _puts("\n[GIET ERROR] in iommu_inval_pte2 function\n");
        _puts("the IOMMU PT1 entry is not mapped / ix1 = ");
        _putx( ix1 );
        _puts("\n");
        _exit();
    }
    else {
        ptba = pt->pt1[ix1] << 12;
        pt_flags = (unsigned int *) (ptba + 8 * ix2);
        *pt_flags = 0;
    }   
} // end _iommu_inval_pte2()


//////////////////////////////////////////////////////////////////////////////
// _v2p_translate()
// Returns 0 if success, 1 if PTE1 or PTE2 unmapped
//////////////////////////////////////////////////////////////////////////////
unsigned int _v2p_translate(
        page_table_t * pt,
        unsigned int vpn,
        unsigned int * ppn,        
        unsigned int * flags) {
    unsigned int ptba;
    register unsigned int * pte2;
    register unsigned int flags_value;
    register unsigned int ppn_value;

    unsigned int ix1 = vpn >> 9;
    unsigned int ix2 = vpn & 0x1FF;
    /*
       _puts("\n\n********************** entering v2p_translate");
       _puts("\n - pt    = ");
       _putx( (unsigned int)pt );
       _puts("\n - vpn   = ");
       _putx( vpn << 12 );
       _puts("\n - ptba  = ");
       _putx( pt->pt1[ix1] << 12 ) ;
       _puts("\n - &pte2 = ");
       _putx( (pt->pt1[ix1] << 12) + 8*ix2 );
       _puts("\n - flags = ");
       _putx( *(unsigned int*)((pt->pt1[ix1] << 12) + 8*ix2) );
       _puts("\n");
       */
    // check PTE1 mapping
    if ((pt->pt1[ix1] & PTE_V) == 0) {
        return 1;
    }
    else {
        // get physical addresses of pte2 
        ptba = pt->pt1[ix1] << 12;
        pte2 = (unsigned int *) (ptba + 8 * ix2);

        // gets ppn_value and flags_value, after temporary DTLB desactivation
        asm volatile (
                "li      $27,    0xFFFFFFFE  \n"     /* Mask for IE bits     */
                "mfc0    $26,    $12         \n"     /* save SR              */ 
                "and     $27,    $26,    $27 \n"
                "mtc0    $27,    $12         \n"     /* disable Interrupts   */

                "li      $27,    0xB         \n"     
                "mtc2    $27,    $1          \n"     /* DTLB unactivated     */ 

                "move    $27,    %2          \n"     /* $27 <= pte2          */
                "lw      %0,     0($27)      \n"     /* read flags           */ 
                "lw      %1,     4($27)      \n"     /* read ppn             */

                "li      $27,    0xF         \n" 
                "mtc2    $27,    $1          \n"     /* DTLB activated       */

                "mtc0    $26,    $12         \n"     /* restore SR           */
                : "=r" (flags_value), "=r" (ppn_value)
                : "r" (pte2)
                : "$26","$27","$8");

        // check PTE2 mapping
        if ((flags_value & PTE_V) == 0) {
            return 1;
        }

        // set return values 
        *ppn = ppn_value;
        *flags = flags_value;
    }
    return 0;
} // end _v2p_translate()

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