WebSVN – HelenOS-historic – Blame – /kernel/trunk/arch/ia32/src/mm/page.c

Rev	Author	Line No.	Line
1	jermar	1	/*
		2	* Copyright (C) 2001-2004 Jakub Jermar
		3	* All rights reserved.
		4	*
		5	* Redistribution and use in source and binary forms, with or without
		6	* modification, are permitted provided that the following conditions
		7	* are met:
		8	*
		9	* - Redistributions of source code must retain the above copyright
		10	* notice, this list of conditions and the following disclaimer.
		11	* - Redistributions in binary form must reproduce the above copyright
		12	* notice, this list of conditions and the following disclaimer in the
		13	* documentation and/or other materials provided with the distribution.
		14	* - The name of the author may not be used to endorse or promote products
		15	* derived from this software without specific prior written permission.
		16	*
		17	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
		18	* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
		19	* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
		20	* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
		21	* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
		22	* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
		23	* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
		24	* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
		25	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
		26	* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
		27	*/
		28
		29	#include <arch/types.h>
		30	#include <config.h>
		31	#include <func.h>
		32	#include <mm/frame.h>
		33	#include <mm/page.h>
		34	#include <arch/mm/page.h>
		35	#include <arch/interrupt.h>
		36	#include <arch/asm.h>
		37	#include <synch/spinlock.h>
106	jermar	38	#include <debug.h>
1	jermar	39
		40	/*
		41	* Note.
11	jermar	42	* This is the preliminary code for controlling paging mechanism on ia32. It is
1	jermar	43	* needed by other parts of the kernel for its ability to map virtual addresses
		44	* to physical. SMP code relies on this feature. Other than that, this code is
		45	* by no means meant to implement virtual memory in terms of swapping pages in
		46	* and out.
		47	*/
		48
		49	__address bootstrap_dba;
		50
		51	void page_arch_init(void)
		52	{
		53	__address dba;
		54	__u32 i;
		55
		56	if (config.cpu_active == 1) {
106	jermar	57	dba = frame_alloc(FRAME_KA \| FRAME_PANIC);
1	jermar	58	memsetb(dba, PAGE_SIZE, 0);
		59
		60	bootstrap_dba = dba;
		61
		62	/*
		63	* Identity mapping for all but 0th page.
105	jermar	64	* PA2KA(identity) mapping for all but 0th page.
1	jermar	65	*/
105	jermar	66	for (i = 1; i < frames; i++) {
1	jermar	67	map_page_to_frame(i * PAGE_SIZE, i * PAGE_SIZE, PAGE_CACHEABLE, 0);
105	jermar	68	map_page_to_frame(PA2KA(i * PAGE_SIZE), i * PAGE_SIZE, PAGE_CACHEABLE, 0);
		69	}
1	jermar	70
		71	trap_register(14, page_fault);
106	jermar	72	cpu_write_dba(KA2PA(dba));
1	jermar	73	}
		74	else {
		75
		76	/*
		77	* Application processors need to create their own view of the
		78	* virtual address space. Because of that, each AP copies
		79	* already-initialized paging information from the bootstrap
		80	* processor and adjusts it to fulfill its needs.
		81	*/
		82
		83	dba = frame_alloc(FRAME_KA \| FRAME_PANIC);
		84	memcopy(bootstrap_dba, dba, PAGE_SIZE);
106	jermar	85	cpu_write_dba(KA2PA(dba));
1	jermar	86	}
		87
		88	paging_on();
		89	}
		90
		91	/*
		92	* Besides mapping pages to frames, this function also sets the present bit of
		93	* the page's specifier in both page directory and respective page table. If
		94	* the page table for this page has not been allocated so far, it will take
		95	* care of it and allocate the necessary frame.
		96	*
		97	* When the copy parameter is positive, map_page_to_frame will not overwrite
		98	* the current mapping. It will allocate a new frame and do the mapping on it
		99	* instead.
		100	*
		101	* PAGE_CACHEABLE flag: when set, it turns caches for that page on
		102	* PAGE_NOT_PRESENT flag: when set, it marks the page not present
		103	* PAGE_USER flag: when set, the page is accessible from userspace
		104	*/
		105	void map_page_to_frame(__address page, __address frame, int flags, int copy)
		106	{
		107	struct page_specifier pd, pt;
		108	__address dba, newpt;
		109	int pde, pte;
		110
105	jermar	111	// TODO: map_page_to_frame should take dba as a parameter
		112	// dba = cpu_read_dba();
		113	dba = bootstrap_dba;
1	jermar	114
		115	pde = page >> 22; /* page directory entry */
		116	pte = (page >> 12) & 0x3ff; /* page table entry */
		117
		118	pd = (struct page_specifier *) dba;
		119
		120	if (!pd[pde].present) {
		121	/*
		122	* There is currently no page table for this address. Allocate
		123	* frame for the page table and clean it.
		124	*/
106	jermar	125	newpt = frame_alloc(FRAME_KA);
		126	pd[pde].frame_address = KA2PA(newpt) >> 12;
1	jermar	127	memsetb(newpt, PAGE_SIZE, 0);
		128	pd[pde].present = 1;
		129	pd[pde].uaccessible = 1;
		130	}
		131	if (copy) {
106	jermar	132	newpt = frame_alloc(FRAME_KA);
1	jermar	133	memcopy(pd[pde].frame_address << 12, newpt, PAGE_SIZE);
106	jermar	134	pd[pde].frame_address = KA2PA(newpt) >> 12;
1	jermar	135	}
34	jermar	136
1	jermar	137	pt = (struct page_specifier *) (pd[pde].frame_address << 12);
		138
		139	pt[pte].frame_address = frame >> 12;
		140	pt[pte].present = !(flags & PAGE_NOT_PRESENT);
		141	pt[pte].page_cache_disable = !(flags & PAGE_CACHEABLE);
		142	pt[pte].uaccessible = (flags & PAGE_USER) != 0;
		143	pt[pte].writeable = (flags & PAGE_WRITE) != 0;
		144	}

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(root)/kernel/trunk/arch/ia32/src/mm/page.c @ 1780 – Rev 106