/*
* 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 <genarch/mm/page_ht.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 <adt/btree.h>
#include <panic.h>
#include <arch/asm.h>
#include <debug.h>
#include <memstr.h>
#include <macros.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);
static as_area_t *find_area_and_lock(as_t *as, __address va);
static bool check_area_conflicts(as_t *as, __address va, size_t size, as_area_t *avoid_area);
/** 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");
btree_create(&as->as_area_btree);
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 flags Flags of the area.
* @param size Size of area.
* @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, int flags, size_t size, __address base)
{
ipl_t ipl;
as_area_t *a;
if (base % PAGE_SIZE)
return NULL;
/* Writeable executable areas are not supported. */
if ((flags & AS_AREA_EXEC) && (flags & AS_AREA_WRITE))
return NULL;
ipl = interrupts_disable();
spinlock_lock(&as->lock);
if (!check_area_conflicts(as, base, size, NULL)) {
spinlock_unlock(&as->lock);
interrupts_restore(ipl);
return NULL;
}
a
= (as_area_t
*) malloc(sizeof(as_area_t
), 0);
spinlock_initialize(&a->lock, "as_area_lock");
a->flags = flags;
a->pages = SIZE2FRAMES(size);
a->base = base;
btree_insert(&as->as_area_btree, base, (void *) a, NULL);
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 *area;
ipl_t ipl;
ipl = interrupts_disable();
page_table_lock(as, true);
area = find_area_and_lock(as, page);
if (!area) {
panic("page not part of any as_area\n");
}
page_mapping_insert(as, page, frame, get_area_flags(area));
spinlock_unlock(&area->lock);
page_table_unlock(as, true);
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)
{
pte_t *pte;
as_area_t *area;
__address frame;
ASSERT(AS);
spinlock_lock(&AS->lock);
area = find_area_and_lock(AS, page);
if (!area) {
/*
* No area contained mapping for 'page'.
* Signal page fault to low-level handler.
*/
spinlock_unlock(&AS->lock);
return 0;
}
page_table_lock(AS, false);
/*
* To avoid race condition between two page faults
* on the same address, we need to make sure
* the mapping has not been already inserted.
*/
if ((pte = page_mapping_find(AS, page))) {
if (PTE_PRESENT(pte)) {
page_table_unlock(AS, false);
spinlock_unlock(&area->lock);
spinlock_unlock(&AS->lock);
return 1;
}
}
/*
* 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));
page_table_unlock(AS, false);
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;
flags = PAGE_USER | PAGE_PRESENT | PAGE_CACHEABLE;
if (a->flags & AS_AREA_READ)
flags |= PAGE_READ;
if (a->flags & AS_AREA_WRITE)
flags |= PAGE_WRITE;
if (a->flags & AS_AREA_EXEC)
flags |= PAGE_EXEC;
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);
}
/** Lock page table.
*
* This function should be called before any page_mapping_insert(),
* page_mapping_remove() and page_mapping_find().
*
* Locking order is such that address space areas must be locked
* prior to this call. Address space can be locked prior to this
* call in which case the lock argument is false.
*
* @param as Address space.
* @param as_locked If false, do not attempt to lock as->lock.
*/
void page_table_lock(as_t *as, bool lock)
{
ASSERT(as_operations);
ASSERT(as_operations->page_table_lock);
as_operations->page_table_lock(as, lock);
}
/** Unlock page table.
*
* @param as Address space.
* @param as_locked If false, do not attempt to unlock as->lock.
*/
void page_table_unlock(as_t *as, bool unlock)
{
ASSERT(as_operations);
ASSERT(as_operations->page_table_unlock);
as_operations->page_table_unlock(as, unlock);
}
/** Find address space area and change it.
*
* @param as Address space.
* @param address Virtual address belonging to the area to be changed. Must be page-aligned.
* @param size New size of the virtual memory block starting at address.
* @param flags Flags influencing the remap operation. Currently unused.
*
* @return address on success, (__address) -1 otherwise.
*/
__address as_remap(as_t *as, __address address, size_t size, int flags)
{
as_area_t *area = NULL;
ipl_t ipl;
size_t pages;
ipl = interrupts_disable();
spinlock_lock(&as->lock);
/*
* Locate the area.
*/
area = find_area_and_lock(as, address);
if (!area) {
spinlock_unlock(&as->lock);
interrupts_restore(ipl);
return (__address) -1;
}
pages = SIZE2FRAMES((address - area->base) + size);
if (pages < area->pages) {
int i;
/*
* Shrinking the area.
* No need to check for overlaps.
*/
for (i = pages; i < area->pages; i++) {
pte_t *pte;
/*
* Releasing physical memory.
* This depends on the fact that the memory was allocated using frame_alloc().
*/
page_table_lock(as, false);
pte = page_mapping_find(as, area->base + i*PAGE_SIZE);
if (pte && PTE_VALID(pte)) {
__address frame;
ASSERT(PTE_PRESENT(pte));
frame = PTE_GET_FRAME(pte);
page_mapping_remove(as, area->base + i*PAGE_SIZE);
page_table_unlock(as, false);
frame_free(ADDR2PFN(frame));
} else {
page_table_unlock(as, false);
}
}
/*
* Invalidate TLB's.
*/
tlb_shootdown_start(TLB_INVL_PAGES, AS->asid, area->base + pages*PAGE_SIZE, area->pages - pages);
tlb_invalidate_pages(AS->asid, area->base + pages*PAGE_SIZE, area->pages - pages);
tlb_shootdown_finalize();
} else {
/*
* Growing the area.
* Check for overlaps with other address space areas.
*/
if (!check_area_conflicts(as, address, pages * PAGE_SIZE, area)) {
spinlock_unlock(&area->lock);
spinlock_unlock(&as->lock);
interrupts_restore(ipl);
return (__address) -1;
}
}
area->pages = pages;
spinlock_unlock(&area->lock);
spinlock_unlock(&as->lock);
interrupts_restore(ipl);
return address;
}
/** Find address space area and lock it.
*
* The address space must be locked and interrupts must be disabled.
*
* @param as Address space.
* @param va Virtual address.
*
* @return Locked address space area containing va on success or NULL on failure.
*/
as_area_t *find_area_and_lock(as_t *as, __address va)
{
as_area_t *a;
btree_node_t *leaf, *lnode;
int i;
a = (as_area_t *) btree_search(&as->as_area_btree, va, &leaf);
if (a) {
/* va is the base address of an address space area */
spinlock_lock(&a->lock);
return a;
}
/*
* Search the leaf node and the righmost record of its left sibling
* to find out whether this is a miss or va belongs to an address
* space area found there.
*/
/* First, search the leaf node itself. */
for (i = 0; i < leaf->keys; i++) {
a = (as_area_t *) leaf->value[i];
spinlock_lock(&a->lock);
if ((a->base <= va) && (va < a->base + a->pages * PAGE_SIZE)) {
return a;
}
spinlock_unlock(&a->lock);
}
/*
* Second, locate the left sibling and test its last record.
* Because of its position in the B+tree, it must have base < va.
*/
if ((lnode = btree_node_left_sibling(&as->as_area_btree, leaf))) {
a = (as_area_t *) lnode->value[lnode->keys - 1];
spinlock_lock(&a->lock);
if (va < a->base + a->pages * PAGE_SIZE) {
return a;
}
spinlock_unlock(&a->lock);
}
return NULL;
}
/** Check area conflicts with other areas.
*
* The address space must be locked and interrupts must be disabled.
*
* @param as Address space.
* @param va Starting virtual address of the area being tested.
* @param size Size of the area being tested.
* @param avoid_area Do not touch this area.
*
* @return True if there is no conflict, false otherwise.
*/
bool check_area_conflicts(as_t *as, __address va, size_t size, as_area_t *avoid_area)
{
as_area_t *a;
btree_node_t *leaf, *node;
int i;
/*
* We don't want any area to have conflicts with NULL page.
*/
if (overlaps(va, size, NULL, PAGE_SIZE))
return false;
/*
* The leaf node is found in O(log n), where n is proportional to
* the number of address space areas belonging to as.
* The check for conflicts is then attempted on the rightmost
* record in the left sibling, the leftmost record in the right
* sibling and all records in the leaf node itself.
*/
if ((a = (as_area_t *) btree_search(&as->as_area_btree, va, &leaf))) {
if (a != avoid_area)
return false;
}
/* First, check the two border cases. */
if ((node = btree_node_left_sibling(&as->as_area_btree, leaf))) {
a = (as_area_t *) node->value[node->keys - 1];
spinlock_lock(&a->lock);
if (overlaps(va, size, a->base, a->pages * PAGE_SIZE)) {
spinlock_unlock(&a->lock);
return false;
}
spinlock_unlock(&a->lock);
}
if ((node = btree_node_right_sibling(&as->as_area_btree, leaf))) {
a = (as_area_t *) node->value[0];
spinlock_lock(&a->lock);
if (overlaps(va, size, a->base, a->pages * PAGE_SIZE)) {
spinlock_unlock(&a->lock);
return false;
}
spinlock_unlock(&a->lock);
}
/* Second, check the leaf node. */
for (i = 0; i < leaf->keys; i++) {
a = (as_area_t *) leaf->value[i];
if (a == avoid_area)
continue;
spinlock_lock(&a->lock);
if (overlaps(va, size, a->base, a->pages * PAGE_SIZE)) {
spinlock_unlock(&a->lock);
return false;
}
spinlock_unlock(&a->lock);
}
/*
* So far, the area does not conflict with other areas.
* Check if it doesn't conflict with kernel address space.
*/
if (!KERNEL_ADDRESS_SPACE_SHADOWED) {
return !overlaps(va, size,
KERNEL_ADDRESS_SPACE_START, KERNEL_ADDRESS_SPACE_END-KERNEL_ADDRESS_SPACE_START);
}
return true;
}