///////////////////////////////////////////////////////////////////////////////////
// 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 = ");
        _putw( 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 = ");
        _putw( 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;

    // 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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