added first version of paging code
(only page_map() works for now)
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9b4714113a
commit
fbf55178c1
6 changed files with 270 additions and 36 deletions
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@ -50,7 +50,7 @@
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/// Page map bits
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#define PAGE_MAP_BITS 10
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/// Number of page map indirections
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#define PAGE_MAP_LEVELS 2
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#define PAGE_LEVELS 2
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/// Mask the page address without page map flags
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#define PAGE_MASK 0xFFFFF000
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@ -93,11 +93,14 @@
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#define PG_BOOT (1 << 9)
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/** @brief A single entry in a page map
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/** @brief Converts a virtual address to a physical
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*
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* Usually used as a pointer to a mapped page map entry.
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* A non mapped virtual address causes a pagefault!
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*
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* @param addr Virtual address to convert
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* @return physical address
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*/
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typedef size_t page_entry_t;
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size_t page_virt_to_phys(size_t vir);
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/** @brief Initialize paging subsystem
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*
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@ -112,27 +115,19 @@ int page_init();
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*
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* @param viraddr
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* @param phyaddr
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* @param pages
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* @param flags
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* @param npages
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* @param bits
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* @return
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*/
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int page_map(size_t viraddr, size_t phyaddr, size_t pages, size_t flags);
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int page_map(size_t viraddr, size_t phyaddr, size_t npages, size_t bits);
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/** @brief Unmap a continious region of pages
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*
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* @param viraddr
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* @param pages
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* @param npages
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* @return
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*/
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int page_unmap(size_t viraddr, size_t pages);
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/** @brief Copy a single page frame
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*
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* @param dest
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* @param src
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* @return
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*/
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int page_copy(size_t dest, size_t src);
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int page_unmap(size_t viraddr, size_t npages);
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/** @brief Copy a whole page map tree
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*
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@ -140,19 +135,12 @@ int page_copy(size_t dest, size_t src);
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* @param src
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* @return
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*/
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int page_map_copy(page_entry_t *dest, page_entry_t *src);
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int page_map_copy(size_t *dest, size_t *src);
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/** @brief Free a whole page map tree
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*
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* @param map
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*/
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int page_map_drop(page_entry_t *map);
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/** @brief Converts a virtual address to a physical
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*
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* @param viraddr Virtual address to convert
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* @return Physical address
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*/
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size_t virt_to_phys(size_t viraddr);
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int page_map_drop(size_t *map);
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#endif
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@ -1,4 +1,4 @@
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;
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; Copyright (c) 2010, Stefan Lankes, RWTH Aachen University
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; All rights reserved.
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;
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@ -318,22 +318,25 @@ ALIGN 4
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mb_info:
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DD 0
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global boot_stack
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ALIGN 4096
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global boot_stack
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boot_stack:
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TIMES (KERNEL_STACK_SIZE) DB 0xcd
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; Bootstrap page tables are used during the initialization.
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; These tables do a simple identity paging and will
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; be replaced in page_init() by more fine-granular mappings.
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global boot_map
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ALIGN 4096
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global boot_map
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boot_map:
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boot_pgd:
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DD boot_pgt + 0x103 ; PG_GLOBAL | PG_RW | PG_PRESENT
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times 1023 DD 0 ; PAGE_MAP_ENTRIES - 1
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boot_pgt:
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%assign i 0
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%rep 1024
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DD (i << 12) | 0x083
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%assign i i+1
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%rep 1024 ; PAGE_MAP_ENTRIES
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DD i | 0x203 ; PG_BOOT | PG_RW | PG_PRESENT
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%assign i i + 4096 ; PAGE_SIZE
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%endrep
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; add some hints to the ELF file
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4
arch/x86/mm/Makefile
Normal file
4
arch/x86/mm/Makefile
Normal file
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@ -0,0 +1,4 @@
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C_source := page.c
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MODULE := arch_x86_mm
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include $(TOPDIR)/Makefile.inc
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arch/x86/mm/page.c
Normal file
238
arch/x86/mm/page.c
Normal file
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@ -0,0 +1,238 @@
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/*
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* Copyright (c) 2010, Stefan Lankes, RWTH Aachen University
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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* * Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* * Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* * Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this
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* software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE FOR ANY
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* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
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* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <eduos/stdio.h>
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#include <eduos/memory.h>
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#include <eduos/errno.h>
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#include <eduos/string.h>
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#include <asm/irq.h>
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#include <asm/page.h>
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#include <asm/io.h>
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/* Note that linker symbols are not variables, they have no memory
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* allocated for maintaining a value, rather their address is their value. */
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extern const void kernel_start;
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extern const void kernel_end;
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/** This PGD table is initialized in entry.asm */
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extern size_t boot_map[PAGE_MAP_ENTRIES];
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/** A self-reference enables direct access to all page tables */
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static size_t* self[PAGE_LEVELS] = {
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(size_t *) PAGE_MAP_PGT, (size_t *) PAGE_MAP_PGD
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};
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#define self_child(lvl, vpn) &self[lvl-1][vpn<<PAGE_MAP_BITS]
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#define self_parent(lvl, vpn) &self[lvl+1][vpn>>PAGE_MAP_BITS]
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/** @todo Does't handle huge pages for now
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* @todo This will cause a pagefaut if addr isn't mapped! */
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size_t page_virt_to_phys(size_t addr)
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{
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size_t vpn = addr >> PAGE_BITS; // virtual page number
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size_t entry = self[0][vpn]; // page table entry
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size_t off = addr & ~PAGE_MASK; // offset within page
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size_t phy = entry & PAGE_MASK; // physical page frame number
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return phy | off;
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}
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int page_map(size_t viraddr, size_t phyaddr, size_t npages, size_t bits)
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{
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int lvl;
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long vpn = viraddr >> PAGE_BITS;
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long first[PAGE_LEVELS], last[PAGE_LEVELS]; // index boundaries for self-mapping
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for (lvl=0; lvl<PAGE_LEVELS; lvl++) {
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first[lvl] = (vpn ) >> (lvl * PAGE_MAP_BITS);
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last[lvl] = (vpn + npages) >> (lvl * PAGE_MAP_BITS);
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}
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/* We start now iterating through the entries
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* beginning at the root table (PGD) */
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for (lvl=PAGE_LEVELS-1; lvl>=0; lvl--) {
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for (vpn=first[lvl]; vpn<=last[lvl]; vpn++) {
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if (lvl) { /* PML4, PDPT, PGD */
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if (self[lvl][vpn] & PG_PRESENT) {
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/* There already an existing table which only allows
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* kernel accesses. We need to copy the table to create
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* private copy for the user space process */
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if (!(self[lvl][vpn] & PG_USER) && (bits & PG_USER)) {
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size_t phyaddr = get_pages(1);
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if (BUILTIN_EXPECT(!phyaddr, 0))
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return -ENOMEM;
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/* Copy old table contents to new one.
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* We temporarily use page zero for this
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* by mapping the new table to this address. */
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page_map(0, phyaddr, 1, PG_RW | PG_PRESENT);
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memcpy(0, self_child(lvl, vpn), PAGE_SIZE);
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/* Update table by replacing address and altering flags */
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self[lvl][vpn] &= ~(PAGE_MASK | PG_GLOBAL);
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self[lvl][vpn] |= phyaddr | PG_USER;
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/* We only need to flush the self-mapped table.
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* TLB entries mapped by this table remain valid
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* because we only made an identical copy. */
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tlb_flush_one_page((size_t) self_child(lvl, vpn));
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}
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}
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else {
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/* There's no table available which covers the region.
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* Therefore we need to create a new empty table. */
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size_t phyaddr = get_pages(1);
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if (BUILTIN_EXPECT(!phyaddr, 0))
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return -ENOMEM;
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/* Reference the new table in the parent */
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self[lvl][vpn] = phyaddr | bits;
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/* Fill new table with zeros */
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memset(self_child(lvl, vpn), 0, PAGE_SIZE);
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}
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}
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else { /* PGT */
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if (self[lvl][vpn] & PG_PRESENT)
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tlb_flush_one_page(vpn << PAGE_BITS);
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self[lvl][vpn] = phyaddr | bits;
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phyaddr += PAGE_SIZE;
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}
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}
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}
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return 0;
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}
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int page_unmap(size_t viraddr, size_t npages)
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{
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int lvl;
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long vpn = viraddr >> PAGE_BITS;
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long first[PAGE_LEVELS], last[PAGE_LEVELS]; // index boundaries for self-mapping
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for (lvl=0; lvl<PAGE_LEVELS; lvl++) {
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first[lvl] = (vpn ) >> (lvl * PAGE_MAP_BITS);
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last[lvl] = (vpn + npages) >> (lvl * PAGE_MAP_BITS);
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}
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/* We start now iterating through the entries
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* beginning at the root table (PGD) */
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for (lvl=PAGE_LEVELS-1; lvl>=0; lvl--) {
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for (vpn=first[lvl]; vpn<=last[lvl]; vpn++) {
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if (lvl) { /* PML4, PDPT, PGD */
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}
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else { /* PGT */
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}
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}
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}
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return 0;
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}
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int page_map_drop(size_t *map)
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{
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int lvl;
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long vpn;
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/* We start now iterating through the entries
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* beginning at the root table (PGD) */
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for (lvl=PAGE_LEVELS-1; lvl>=0; lvl--) {
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for (vpn=0; vpn<PAGE_MAP_ENTRIES; vpn++) {
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if (lvl) { /* PML4, PDPT, PGD */
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}
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else { /* PGT */
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}
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}
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}
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return 0;
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}
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int page_map_copy(size_t *dest, size_t *src)
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{
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int lvl;
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long vpn;
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/* We start now iterating through the entries
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* beginning at the root table (PGD) */
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for (lvl=PAGE_LEVELS-1; lvl>=0; lvl--) {
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for (vpn=0; vpn<PAGE_MAP_ENTRIES; vpn++) {
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if (lvl) { /* PML4, PDPT, PGD */
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}
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else { /* PGT */
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}
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}
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}
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return 0;
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}
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void page_fault_handler(struct state *s)
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{
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size_t viraddr = read_cr2();
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kprintf("Page Fault Exception (%d) at cs:ip = %#x:%#lx, address = %#lx\n",
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s->int_no, s->cs, s->eip, viraddr);
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outportb(0x20, 0x20);
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while(1) HALT;
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}
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int page_init()
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{
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size_t npages;
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// replace default pagefault handler
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irq_uninstall_handler(14);
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irq_install_handler(14, page_fault_handler);
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// create self-reference
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boot_map[PAGE_MAP_ENTRIES-1] = (size_t) &boot_map | PG_PRESENT | PG_RW;
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// map kernel
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npages = PAGE_FLOOR((size_t) &kernel_end - (size_t) &kernel_start) >> PAGE_BITS;
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page_map((size_t) &kernel_start, (size_t) &kernel_start, npages, PG_PRESENT | PG_RW | PG_GLOBAL);
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#ifdef CONFIG_VGA
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// map video memory
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page_map(VIDEO_MEM_ADDR, VIDEO_MEM_ADDR, 1, PG_PCD | PG_PRESENT | PG_RW);
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#endif
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// flush TLB to apply new mappings
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flush_tlb();
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return 0;
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}
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// initialize .bss section
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memset((void*)&bss_start, 0x00, ((size_t) &bss_end - (size_t) &bss_start));
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memory_init();
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system_init();
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irq_init();
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timer_init();
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koutput_init();
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multitasking_init();
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memory_init();
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return 0;
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}
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@ -230,10 +230,11 @@ int memory_init(void)
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}
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// enable paging and map SMP, VGA, Multiboot modules etc.
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/*ret = page_init();
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if (BUILTIN_EXPECT(ret, 0))
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ret = page_init();
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if (BUILTIN_EXPECT(ret, 0)) {
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kputs("Failed to initialize paging!\n");
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return ret;
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*/
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}
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return ret;
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}
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Add table
Reference in a new issue