/*
* Copyright (C) 2001-2004 Jakub Jermar
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* - Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* - The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <arch/types.h>
#include <config.h>
#include <func.h>
#include <mm/frame.h>
#include <mm/page.h>
#include <arch/mm/page.h>
#include <arch/interrupt.h>
#include <arch/asm.h>
#include <synch/spinlock.h>
#include <debug.h>
/*
* Note.
* This is the preliminary code for controlling paging mechanism on ia32. It is
* needed by other parts of the kernel for its ability to map virtual addresses
* to physical. SMP code relies on this feature. Other than that, this code is
* by no means meant to implement virtual memory in terms of swapping pages in
* and out.
*/
__address bootstrap_dba;
void page_arch_init(void)
{
__address dba;
__u32 i;
if (config.cpu_active == 1) {
dba = frame_alloc(FRAME_KA | FRAME_PANIC);
memsetb(dba, PAGE_SIZE, 0);
bootstrap_dba = dba;
/*
* Identity mapping for all but 0th page.
* PA2KA(identity) mapping for all but 0th page.
*/
for (i = 1; i < frames; i++) {
map_page_to_frame(i * PAGE_SIZE, i * PAGE_SIZE, PAGE_CACHEABLE, 0);
map_page_to_frame(PA2KA(i * PAGE_SIZE), i * PAGE_SIZE, PAGE_CACHEABLE, 0);
}
trap_register(14, page_fault);
cpu_write_dba(KA2PA(dba));
}
else {
/*
* Application processors need to create their own view of the
* virtual address space. Because of that, each AP copies
* already-initialized paging information from the bootstrap
* processor and adjusts it to fulfill its needs.
*/
dba = frame_alloc(FRAME_KA | FRAME_PANIC);
memcopy(bootstrap_dba, dba, PAGE_SIZE);
cpu_write_dba(KA2PA(dba));
}
paging_on();
}
/*
* Besides mapping pages to frames, this function also sets the present bit of
* the page's specifier in both page directory and respective page table. If
* the page table for this page has not been allocated so far, it will take
* care of it and allocate the necessary frame.
*
* When the copy parameter is positive, map_page_to_frame will not overwrite
* the current mapping. It will allocate a new frame and do the mapping on it
* instead.
*
* PAGE_CACHEABLE flag: when set, it turns caches for that page on
* PAGE_NOT_PRESENT flag: when set, it marks the page not present
* PAGE_USER flag: when set, the page is accessible from userspace
*/
void map_page_to_frame(__address page, __address frame, int flags, int copy)
{
struct page_specifier *pd, *pt;
__address dba, newpt;
int pde, pte;
// TODO: map_page_to_frame should take dba as a parameter
// dba = cpu_read_dba();
dba = bootstrap_dba;
pde = page >> 22; /* page directory entry */
pte = (page >> 12) & 0x3ff; /* page table entry */
pd = (struct page_specifier *) dba;
if (!pd[pde].present) {
/*
* There is currently no page table for this address. Allocate
* frame for the page table and clean it.
*/
newpt = frame_alloc(FRAME_KA);
pd[pde].frame_address = KA2PA(newpt) >> 12;
memsetb(newpt, PAGE_SIZE, 0);
pd[pde].present = 1;
pd[pde].uaccessible = 1;
}
if (copy) {
newpt = frame_alloc(FRAME_KA);
memcopy(pd[pde].frame_address << 12, newpt, PAGE_SIZE);
pd[pde].frame_address = KA2PA(newpt) >> 12;
}
pt = (struct page_specifier *) (pd[pde].frame_address << 12);
pt[pte].frame_address = frame >> 12;
pt[pte].present = !(flags & PAGE_NOT_PRESENT);
pt[pte].page_cache_disable = !(flags & PAGE_CACHEABLE);
pt[pte].uaccessible = (flags & PAGE_USER) != 0;
pt[pte].writeable = (flags & PAGE_WRITE) != 0;
}