66 lines
2.6 KiB
C
66 lines
2.6 KiB
C
/*
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Copyright (C) 2012, Aaron Lindsay <aaron@aclindsay.com>
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This file is part of Aedrix.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License along
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with this program; if not, write to the Free Software Foundation, Inc.,
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51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*/
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#include <print.h>
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#include <types.h>
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#include <arch/properties.h>
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#define PAGE_SIZE 0x00400000
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#define ROUND_DOWN_PAGE_SIZE(addr) ((typeof(addr))((uint32)(addr) & 0xff800000))
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static inline int page_intersects(uint32 *page_start, uint32 *lower, uint32 *upper) {
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return (lower >= page_start && lower < (page_start + (PAGE_SIZE>>2))) ||
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(upper >= page_start && upper < (page_start + (PAGE_SIZE>>2))) ||
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(lower < page_start && upper >= (page_start + (PAGE_SIZE>>2)));
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}
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void mmu_reinit() {
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uint32 virt_phys_offset; /* CAUTION: 1 = 4 bytes */
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uint32 *curr_tbl_entry;
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uint32 *curr_addr;
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uint32 *page_dir;
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asm("movl %%cr3, %0" : "=r"(page_dir) : : );
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virt_phys_offset = kernel_start_virtual() - kernel_start_physical();
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curr_tbl_entry = page_dir + virt_phys_offset;
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//do first loop iteration outside th eloop, because we have to check against wrapping back around to know we're done
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*curr_tbl_entry = 0x83;
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curr_tbl_entry++;
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//create identity mapping for entire address space using sections.
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//BUT, if we've relocated the kernel from where it is in physical
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//memory, make sure we keep those mappings correct, and we'll actually
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//swap the two mappings so all of memory is addressable.
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for (curr_addr = (uint32 *)PAGE_SIZE; curr_addr != 0; curr_addr += (PAGE_SIZE>>2)) {
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if (page_intersects(curr_addr, kernel_start_physical(), kernel_end_physical())) {
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*curr_tbl_entry = (uint32)ROUND_DOWN_PAGE_SIZE(curr_addr + virt_phys_offset) | 0x83;
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} else if (page_intersects(curr_addr, kernel_start_virtual(), kernel_end_virtual())) {
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*curr_tbl_entry = (uint32)ROUND_DOWN_PAGE_SIZE(curr_addr - virt_phys_offset) | 0x83;
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} else {
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*curr_tbl_entry = (uint32)curr_addr | 0x83;
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}
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/* Force the entries to reload */
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asm("invlpg (%0)" : : "r"(curr_addr) : );
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curr_tbl_entry++;
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}
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}
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