Subversion Repositories HelenOS

#include <arch/arch.h>

#include <arch/mm/tlb.h>

#include <mm/asid.h>

/** Take over TLB and trap table.

 *

 * Initialize ITLB and DTLB and switch to kernel

 * trap table.

 *

 * The goal of this function is to disable MMU

 * so that both TLBs can be purged and new

 * kernel 4M locked entry can be installed.

 * After TLB is initialized, MMU is enabled

 * again.

 *

 * Switching MMU off imposes the requirement for

 * the kernel to run in identity mapped environment.

 *

 * @param base Base address that will be hardwired in both TLBs.

 */

void take_over_tlb_and_tt(uintptr_t base)

{

    tlb_tag_access_reg_t tag;

    tlb_data_t data;

    frame_address_t fr;

    page_address_t pg;

    fr.address = base;

    pg.address = base;

    immu_disable();

    dmmu_disable();

    /*

     * Demap everything, especially OpenFirmware.

     */

    itlb_demap(TLB_DEMAP_CONTEXT, TLB_DEMAP_NUCLEUS, 0);

    dtlb_demap(TLB_DEMAP_CONTEXT, TLB_DEMAP_NUCLEUS, 0);

    /*

     * We do identity mapping of 4M-page at 4M.

     */

    tag.value = ASID_KERNEL;

    tag.vpn = pg.vpn;

    itlb_tag_access_write(tag.value);

    dtlb_tag_access_write(tag.value);

    data.value = 0;

    data.v = true;

    data.size = PAGESIZE_4M;

    data.pfn = fr.pfn;

    data.l = true;

    data.cp = 1;

    data.cv = 1;

    data.p = true;

    data.w = true;

    data.g = true;

    itlb_data_in_write(data.value);

    dtlb_data_in_write(data.value);

    /*

     * Register window traps can occur before MMU is enabled again.

     * This ensures that any such traps will be handled from

     * kernel identity mapped trap handler.

     */

    trap_switch_trap_table();

    tlb_invalidate_all();

    dmmu_enable();

    immu_enable();

}