eduOS/arch/x86/mm/page.c

285 lines
8.3 KiB
C

/*
* Copyright (c) 2010, Stefan Lankes, RWTH Aachen University
* 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.
* * Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this
* software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "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 REGENTS OR CONTRIBUTORS 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.
*/
/**
* This is a 32/64 bit portable paging implementation for the x86 architecture
* using self-referenced page tables.
* See http://www.noteblok.net/2014/06/14/bachelor/ for a detailed description.
*/
#include <eduos/stdio.h>
#include <eduos/memory.h>
#include <eduos/errno.h>
#include <eduos/string.h>
#include <eduos/spinlock.h>
#include <asm/irq.h>
#include <asm/page.h>
#include <asm/io.h>
#include <asm/multiboot.h>
/* Note that linker symbols are not variables, they have no memory
* allocated for maintaining a value, rather their address is their value. */
extern const void kernel_start;
extern const void kernel_end;
/** Lock for kernel space page tables */
static spinlock_t kslock = SPINLOCK_INIT;
/** This PGD table is initialized in entry.asm */
extern size_t boot_map[PAGE_MAP_ENTRIES];
/** A self-reference enables direct access to all page tables */
static size_t* self[PAGE_LEVELS] = {
(size_t *) 0xFFC00000,
(size_t *) 0xFFFFF000
};
/** An other self-reference for page_map_copy() */
static size_t * other[PAGE_LEVELS] = {
(size_t *) 0xFF800000,
(size_t *) 0xFFFFE000
};
/* Addresses of child/parent tables */
#define CHILD(map, lvl, vpn) &map[lvl-1][vpn<<PAGE_MAP_BITS]
#define PARENT(map, lvl, vpn) &map[lvl+1][vpn>>PAGE_MAP_BITS]
size_t page_virt_to_phys(size_t addr)
{
size_t vpn = addr >> PAGE_BITS; // virtual page number
size_t entry = self[0][vpn]; // page table entry
size_t off = addr & ~PAGE_MASK; // offset within page
size_t phy = entry & PAGE_MASK; // physical page frame number
return phy | off;
}
int page_map(size_t viraddr, size_t phyaddr, size_t npages, size_t bits)
{
int lvl;
long vpn = viraddr >> PAGE_BITS;
long first[PAGE_LEVELS], last[PAGE_LEVELS];
/* Calculate index boundaries for page map traversal */
for (lvl=0; lvl<PAGE_LEVELS; lvl++) {
first[lvl] = (vpn ) >> (lvl * PAGE_MAP_BITS);
last[lvl] = (vpn+npages-1) >> (lvl * PAGE_MAP_BITS);
}
spinlock_lock(&kslock);
/* Start iterating through the entries
* beginning at the root table (PGD or PML4) */
for (lvl=PAGE_LEVELS-1; lvl>=0; lvl--) {
for (vpn=first[lvl]; vpn<=last[lvl]; vpn++) {
if (lvl) { /* PML4, PDPT, PGD */
if (!(self[lvl][vpn] & PG_PRESENT)) {
/* There's no table available which covers the region.
* Therefore we need to create a new empty table. */
size_t phyaddr = get_pages(1);
if (BUILTIN_EXPECT(!phyaddr, 0)) {
spinlock_unlock(&kslock);
return -ENOMEM;
}
/* Reference the new table within its parent */
self[lvl][vpn] = phyaddr | bits;
/* Fill new table with zeros */
memset(CHILD(self, lvl, vpn), 0, PAGE_SIZE);
}
}
else { /* PGT */
if (self[lvl][vpn] & PG_PRESENT)
/* There's already a page mapped at this address.
* We have to flush a single TLB entry. */
tlb_flush_one_page(vpn << PAGE_BITS);
self[lvl][vpn] = phyaddr | bits;
phyaddr += PAGE_SIZE;
}
}
}
spinlock_unlock(&kslock);
return 0;
}
/** Tables are freed by page_map_drop() */
int page_unmap(size_t viraddr, size_t npages)
{
long vpn, start = viraddr >> PAGE_BITS;
long end = start + npages;
spinlock_lock(&kslock);
/* Start iterating through the entries.
* Only the PGT entries are removed. Tables remain allocated. */
for (vpn=start; vpn<end; vpn++)
self[0][vpn] = 0;
spinlock_unlock(&kslock);
return 0;
}
int page_map_drop()
{
void traverse(int lvl, long vpn) {
kprintf("traverse(lvl=%d, vpn=%#lx)\n", lvl, vpn);
long stop;
for (stop=vpn+PAGE_MAP_ENTRIES; vpn<stop; vpn++) {
if (self[lvl][vpn] & PG_PRESENT) {
if (self[lvl][vpn] & PG_BOOT)
continue;
// ost-order traversal
if (lvl > 1)
traverse(lvl-1, vpn<<PAGE_MAP_BITS);
kprintf("%#lx, ", self[lvl][vpn] & PAGE_MASK);
//put_page(self[lvl][vpn] & PAGE_MASK);
atomic_int32_dec(&current_task->user_usage);
}
}
}
spinlock_irqsave_lock(&current_task->page_lock);
traverse(PAGE_LEVELS-1, 0);
spinlock_irqsave_unlock(&current_task->page_lock);
return 0;
}
int page_map_copy(size_t dest)
{
int traverse(int lvl, long vpn) {
long stop;
for (stop=vpn+PAGE_MAP_ENTRIES; vpn<stop; vpn++) {
if (self[lvl][vpn] & PG_PRESENT) {
size_t phyaddr = get_pages(1);
if (BUILTIN_EXPECT(phyaddr, 0))
return -ENOMEM;
other[lvl][vpn] = phyaddr;
other[lvl][vpn] |= self[lvl][vpn] & ~PAGE_MASK;
memcpy(CHILD(other, lvl, vpn), CHILD(self, lvl, vpn), PAGE_SIZE);
// pre-order traversal
if (lvl)
traverse(lvl-1, vpn<<PAGE_MAP_BITS);
}
}
return 0;
}
spinlock_lock(&kslock);
// create another temporary self-reference
self[PAGE_LEVELS-1][PAGE_MAP_ENTRIES-2] = dest | PG_PRESENT | PG_RW;
traverse(PAGE_LEVELS-1, 0);
// remove temporary self-reference
self[PAGE_LEVELS-1][PAGE_MAP_ENTRIES-2] = 0;
spinlock_unlock(&kslock);
return 0;
}
void page_fault_handler(struct state *s)
{
size_t viraddr = read_cr2();
kprintf("Page Fault Exception (%d) at cs:ip = %#x:%#lx, task = %u, addr = %#lx, error = %#x [ %s %s %s %s %s ]\n",
s->int_no, s->cs, s->eip, current_task->id, viraddr, s->error,
(s->error & 0x4) ? "user" : "supervisor",
(s->error & 0x10) ? "instruction" : "data",
(s->error & 0x2) ? "write" : ((s->error & 0x10) ? "fetch" : "read"),
(s->error & 0x1) ? "protection" : "not present",
(s->error & 0x8) ? "reserved bit" : "\b");
while(1) HALT;
}
int page_init()
{
size_t addr, npages;
int i;
/* Replace default pagefault handler */
irq_uninstall_handler(14);
irq_install_handler(14, page_fault_handler);
/* Map kernel */
addr = (size_t) &kernel_start;
npages = PAGE_FLOOR((size_t) &kernel_end - (size_t) &kernel_start) >> PAGE_BITS;
page_map(addr, addr, npages, PG_PRESENT | PG_RW | PG_GLOBAL);
#ifdef CONFIG_VGA
/* Map video memory */
page_map(VIDEO_MEM_ADDR, VIDEO_MEM_ADDR, 1, PG_PRESENT | PG_RW | PG_PCD);
#endif
/* Map multiboot information and modules */
if (mb_info) {
addr = (size_t) mb_info & PAGE_MASK;
npages = PAGE_FLOOR(sizeof(*mb_info)) >> PAGE_BITS;
page_map(addr, addr, npages, PG_PRESENT | PG_GLOBAL);
if (mb_info->flags & MULTIBOOT_INFO_MODS) {
addr = mb_info->mods_addr;
npages = PAGE_FLOOR(mb_info->mods_count*sizeof(multiboot_module_t)) >> PAGE_BITS;
page_map(addr, addr, npages, PG_PRESENT | PG_GLOBAL);
multiboot_module_t* mmodule = (multiboot_module_t*) ((size_t) mb_info->mods_addr);
for(i=0; i<mb_info->mods_count; i++) {
addr = mmodule[i].mod_start;
npages = PAGE_FLOOR(mmodule[i].mod_end - mmodule[i].mod_start) >> PAGE_BITS;
page_map(addr, addr, npages, PG_PRESENT | PG_USER | PG_GLOBAL);
}
}
}
/* Unmap bootstrap identity paging (see entry.asm, PG_BOOT) */
for (i=0; i<PAGE_MAP_ENTRIES; i++) {
if (self[0][i] & PG_BOOT) {
self[0][i] = 0;
tlb_flush_one_page(i << PAGE_BITS);
}
}
return 0;
}