source: soft/giet_vm/giet_common/vmem.c @ 447

///////////////////////////////////////////////////////////////////////////////////
// File     : vmem.c
// Date     : 01/07/2012
// Author   : alain greiner
// Copyright (c) UPMC-LIP6
///////////////////////////////////////////////////////////////////////////////////

#include <utils.h>
#include <vmem.h>
#include <giet_config.h>

//////////////////////////////////////////////////
unsigned int _v2p_translate( page_table_t*  ptab,
                             unsigned int   vpn,
                             unsigned int*  ppn,
                             unsigned int*  flags ) 
{
    unsigned long long ptba;
    unsigned long long pte2_paddr;

    unsigned int pte2_msb;
    unsigned int pte2_lsb;
    unsigned int flags_value;
    unsigned int ppn_value;

    unsigned int ix1 = vpn >> 9;
    unsigned int ix2 = vpn & 0x1FF;

    unsigned int save_sr;

    // get PTE1
    unsigned int pte1 = ptab->pt1[ix1];

    // check PTE1 mapping
    if ( (pte1 & PTE_V) == 0 )
    {
        _puts("\n[VMEM ERROR] _v2p_translate() : pte1 unmapped\n");
        _exit();
    }

    // test big/small page
    if ( (pte1 & PTE_T) == 0 )  // big page
    {
        // set return values
        *ppn   = ((pte1 << 9) & 0x0FFFFE00) | (vpn & 0X000001FF);
        *flags = pte1 & 0xFFC00000;
    }
    else                        // small page
    {

        // get physical addresses of pte2 (two 32 bits words)
        ptba       = (unsigned long long) (pte1 & 0x0FFFFFFF) << 12;
        pte2_paddr = ptba + 8*ix2;
        pte2_lsb   = (unsigned int) pte2_paddr;
        pte2_msb   = (unsigned int) (pte2_paddr >> 32);

        // disable interrupts and save status register
        _it_disable( &save_sr );

        // get ppn_value and flags_value, using a physical read
        // after temporary DTLB desactivation
        asm volatile (
                "mfc2    $2,     $1          \n"     /* $2 <= MMU_MODE       */
                "andi    $3,     $2,    0xb  \n"
                "mtc2    $3,     $1          \n"     /* DTLB off             */

                "move    $4,     %3          \n"     /* $4 <= pte_lsb        */
                "mtc2    %2,     $24         \n"     /* PADDR_EXT <= pte_msb */
                "lw      %0,     0($4)       \n"     /* read flags           */ 
                "lw      %1,     4($4)       \n"     /* read ppn             */
                "mtc2    $0,     $24         \n"     /* PADDR_EXT <= 0       */

                "mtc2    $2,     $1          \n"     /* restore MMU_MODE     */
                : "=r" (flags_value), "=r" (ppn_value)
                : "r"  (pte2_msb)   , "r"  (pte2_lsb)
                : "$2", "$3", "$4" );

        // restore saved status register
        _it_restore( &save_sr );

        // set return values 
        *ppn   = ppn_value   & 0x0FFFFFFF;
        *flags = flags_value & 0xFFC00000;

        // check PTE2 mapping
        if ( (flags_value & PTE_V) == 0 )
        {
            _puts("\n[VMEM ERROR] _v2p_translate() : pte2 unmapped\n");
            _exit();
        }
    }
    return 0;
} // end _v2p_translate()



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