/*
* Copyright (C) 2001-2006 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.
*/
/*
* This file contains address space manipulation functions.
* Roughly speaking, this is a higher-level client of
* Virtual Address Translation (VAT) subsystem.
*/
#include <mm/as.h>
#include <arch/mm/as.h>
#include <mm/page.h>
#include <mm/frame.h>
#include <mm/slab.h>
#include <mm/tlb.h>
#include <arch/mm/page.h>
#include <genarch/mm/page_pt.h>
#include <mm/asid.h>
#include <arch/mm/asid.h>
#include <arch/types.h>
#include <typedefs.h>
#include <synch/spinlock.h>
#include <config.h>
#include <adt/list.h>
#include <panic.h>
#include <arch/asm.h>
#include <debug.h>
#include <memstr.h>
#include <arch.h>
#include <print.h>
as_operations_t *as_operations = NULL;
/** Address space lock. It protects inactive_as_with_asid_head. */
SPINLOCK_INITIALIZE(as_lock);
/**
* This list contains address spaces that are not active on any
* processor and that have valid ASID.
*/
LIST_INITIALIZE(inactive_as_with_asid_head);
/** Kernel address space. */
as_t *AS_KERNEL = NULL;
static int get_area_flags(as_area_t *a);
/** Initialize address space subsystem. */
void as_init(void)
{
as_arch_init();
AS_KERNEL = as_create(FLAG_AS_KERNEL);
if (!AS_KERNEL)
panic("can't create kernel address space\n");
}
/** Create address space.
*
* @param flags Flags that influence way in wich the address space is created.
*/
as_t *as_create(int flags)
{
as_t *as;
as
= (as_t
*) malloc(sizeof(as_t
), 0); link_initialize(&as->inactive_as_with_asid_link);
spinlock_initialize(&as->lock, "as_lock");
list_initialize(&as->as_area_head);
if (flags & FLAG_AS_KERNEL)
as->asid = ASID_KERNEL;
else
as->asid = ASID_INVALID;
as->refcount = 0;
as->page_table = page_table_create(flags);
return as;
}
/** Free Adress space */
void as_free(as_t *as)
{
ASSERT(as->refcount == 0);
/* TODO: free as_areas and other resources held by as */
/* TODO: free page table */
}
/** Create address space area of common attributes.
*
* The created address space area is added to the target address space.
*
* @param as Target address space.
* @param type Type of area.
* @param size Size of area in multiples of PAGE_SIZE.
* @param base Base address of area.
*
* @return Address space area on success or NULL on failure.
*/
as_area_t *as_area_create(as_t *as, as_area_type_t type, size_t size, __address base)
{
ipl_t ipl;
as_area_t *a;
if (base % PAGE_SIZE)
panic("addr not aligned to a page boundary");
ipl = interrupts_disable();
spinlock_lock(&as->lock);
/*
* TODO: test as_area which is to be created doesn't overlap with an existing one.
*/
a
= (as_area_t
*) malloc(sizeof(as_area_t
), 0);
spinlock_initialize(&a->lock, "as_area_lock");
link_initialize(&a->link);
a->type = type;
a->size = size;
a->base = base;
list_append(&a->link, &as->as_area_head);
spinlock_unlock(&as->lock);
interrupts_restore(ipl);
return a;
}
/** Initialize mapping for one page of address space.
*
* This functions maps 'page' to 'frame' according
* to attributes of the address space area to
* wich 'page' belongs.
*
* @param as Target address space.
* @param page Virtual page within the area.
* @param frame Physical frame to which page will be mapped.
*/
void as_set_mapping(as_t *as, __address page, __address frame)
{
as_area_t *a, *area = NULL;
link_t *cur;
ipl_t ipl;
ipl = interrupts_disable();
spinlock_lock(&as->lock);
/*
* First, try locate an area.
*/
for (cur = as->as_area_head.next; cur != &as->as_area_head; cur = cur->next) {
a = list_get_instance(cur, as_area_t, link);
spinlock_lock(&a->lock);
if ((page >= a->base) && (page < a->base + a->size * PAGE_SIZE)) {
area = a;
break;
}
spinlock_unlock(&a->lock);
}
if (!area) {
panic("page not part of any as_area\n");
}
/*
* Note: area->lock is held.
*/
page_mapping_insert(as, page, frame, get_area_flags(area));
spinlock_unlock(&area->lock);
spinlock_unlock(&as->lock);
interrupts_restore(ipl);
}
/** Handle page fault within the current address space.
*
* This is the high-level page fault handler.
* Interrupts are assumed disabled.
*
* @param page Faulting page.
*
* @return 0 on page fault, 1 on success.
*/
int as_page_fault(__address page)
{
link_t *cur;
as_area_t *a, *area = NULL;
__address frame;
ASSERT(AS);
spinlock_lock(&AS->lock);
/*
* Search this areas of this address space for presence of 'page'.
*/
for (cur = AS->as_area_head.next; cur != &AS->as_area_head; cur = cur->next) {
a = list_get_instance(cur, as_area_t, link);
spinlock_lock(&a->lock);
if ((page >= a->base) && (page < a->base + a->size * PAGE_SIZE)) {
/*
* We found the area containing 'page'.
* TODO: access checking
*/
area = a;
break;
}
spinlock_unlock(&a->lock);
}
if (!area) {
/*
* No area contained mapping for 'page'.
* Signal page fault to low-level handler.
*/
spinlock_unlock(&AS->lock);
return 0;
}
/*
* Note: area->lock is held.
*/
/*
* In general, there can be several reasons that
* can have caused this fault.
*
* - non-existent mapping: the area is a scratch
* area (e.g. stack) and so far has not been
* allocated a frame for the faulting page
*
* - non-present mapping: another possibility,
* currently not implemented, would be frame
* reuse; when this becomes a possibility,
* do not forget to distinguish between
* the different causes
*/
frame = PFN2ADDR(frame_alloc(ONE_FRAME, 0));
memsetb(PA2KA(frame), FRAME_SIZE, 0);
/*
* Map 'page' to 'frame'.
* Note that TLB shootdown is not attempted as only new information is being
* inserted into page tables.
*/
page_mapping_insert(AS, page, frame, get_area_flags(area));
spinlock_unlock(&area->lock);
spinlock_unlock(&AS->lock);
return 1;
}
/** Switch address spaces.
*
* @param old Old address space or NULL.
* @param new New address space.
*/
void as_switch(as_t *old, as_t *new)
{
ipl_t ipl;
bool needs_asid = false;
ipl = interrupts_disable();
spinlock_lock(&as_lock);
/*
* First, take care of the old address space.
*/
if (old) {
spinlock_lock(&old->lock);
ASSERT(old->refcount);
if((--old->refcount == 0) && (old != AS_KERNEL)) {
/*
* The old address space is no longer active on
* any processor. It can be appended to the
* list of inactive address spaces with assigned
* ASID.
*/
ASSERT(old->asid != ASID_INVALID);
list_append(&old->inactive_as_with_asid_link, &inactive_as_with_asid_head);
}
spinlock_unlock(&old->lock);
}
/*
* Second, prepare the new address space.
*/
spinlock_lock(&new->lock);
if ((new->refcount++ == 0) && (new != AS_KERNEL)) {
if (new->asid != ASID_INVALID)
list_remove(&new->inactive_as_with_asid_link);
else
needs_asid = true; /* defer call to asid_get() until new->lock is released */
}
SET_PTL0_ADDRESS(new->page_table);
spinlock_unlock(&new->lock);
if (needs_asid) {
/*
* Allocation of new ASID was deferred
* until now in order to avoid deadlock.
*/
asid_t asid;
asid = asid_get();
spinlock_lock(&new->lock);
new->asid = asid;
spinlock_unlock(&new->lock);
}
spinlock_unlock(&as_lock);
interrupts_restore(ipl);
/*
* Perform architecture-specific steps.
* (e.g. write ASID to hardware register etc.)
*/
as_install_arch(new);
AS = new;
}
/** Compute flags for virtual address translation subsytem.
*
* The address space area must be locked.
* Interrupts must be disabled.
*
* @param a Address space area.
*
* @return Flags to be used in page_mapping_insert().
*/
int get_area_flags(as_area_t *a)
{
int flags;
switch (a->type) {
case AS_AREA_TEXT:
flags = PAGE_EXEC | PAGE_READ | PAGE_USER | PAGE_PRESENT | PAGE_CACHEABLE;
break;
case AS_AREA_DATA:
case AS_AREA_STACK:
flags = PAGE_READ | PAGE_WRITE | PAGE_USER | PAGE_PRESENT | PAGE_CACHEABLE;
break;
default:
panic("unexpected as_area_type_t %d", a->type);
}
return flags;
}
/** Create page table.
*
* Depending on architecture, create either address space
* private or global page table.
*
* @param flags Flags saying whether the page table is for kernel address space.
*
* @return First entry of the page table.
*/
pte_t *page_table_create(int flags)
{
ASSERT(as_operations);
ASSERT(as_operations->page_table_create);
return as_operations->page_table_create(flags);
}