Rev 1409 | Rev 1413 | Go to most recent revision | Blame | Compare with Previous | Last modification | View Log | Download | RSS feed
/*
* 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.
*/
/**
* @file as.c
* @brief Address space related functions.
*
* This file contains address space manipulation functions.
* Roughly speaking, this is a higher-level client of
* Virtual Address Translation (VAT) subsystem.
*
* Functionality provided by this file allows one to
* create address space and create, resize and share
* address space areas.
*
* @see page.c
*
*/
#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 <synch/spinlock.h>
#include <synch/mutex.h>
#include <adt/list.h>
#include <adt/btree.h>
#include <proc/task.h>
#include <proc/thread.h>
#include <arch/asm.h>
#include <panic.h>
#include <debug.h>
#include <print.h>
#include <memstr.h>
#include <macros.h>
#include <arch.h>
#include <errno.h>
#include <config.h>
#include <align.h>
#include <arch/types.h>
#include <typedefs.h>
#include <syscall/copy.h>
#include <arch/interrupt.h>
/** This structure contains information associated with the shared address space area. */
struct share_info {
mutex_t lock; /**< This lock must be acquired only when the as_area lock is held. */
count_t refcount; /**< This structure can be deallocated if refcount drops to 0. */
btree_t pagemap; /**< B+tree containing complete map of anonymous pages of the shared area. */
};
as_operations_t *as_operations = NULL;
/** Address space lock. It protects inactive_as_with_asid_head. Must be acquired before as_t mutex. */
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 area_flags_to_page_flags(int aflags);
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);
static void sh_info_remove_reference(share_info_t *sh_info);
/** 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);
mutex_initialize(&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 */
free(as);
}
/** 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 memory.
* @param size Size of area.
* @param base Base address of area.
* @param attrs Attributes of the area.
* @param backend Address space area backend. NULL if no backend is used.
* @param backend_data NULL or a pointer to an array holding two void *.
*
* @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, int attrs,
mem_backend_t *backend, void **backend_data)
{
ipl_t ipl;
as_area_t *a;
if (base % PAGE_SIZE)
return NULL;
if (!size)
return NULL;
/* Writeable executable areas are not supported. */
if ((flags & AS_AREA_EXEC) && (flags & AS_AREA_WRITE))
return NULL;
ipl = interrupts_disable();
mutex_lock(&as->lock);
if (!check_area_conflicts(as, base, size, NULL)) {
mutex_unlock(&as->lock);
interrupts_restore(ipl);
return NULL;
}
a = (as_area_t *) malloc(sizeof(as_area_t), 0);
mutex_initialize(&a->lock);
a->flags = flags;
a->attributes = attrs;
a->pages = SIZE2FRAMES(size);
a->base = base;
a->sh_info = NULL;
a->backend = backend;
if (backend_data) {
a->backend_data[0] = backend_data[0];
a->backend_data[1] = backend_data[1];
}
btree_create(&a->used_space);
btree_insert(&as->as_area_btree, base, (void *) a, NULL);
mutex_unlock(&as->lock);
interrupts_restore(ipl);
return a;
}
/** 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 Zero on success or a value from @ref errno.h otherwise.
*/
int as_area_resize(as_t *as, __address address, size_t size, int flags)
{
as_area_t *area;
ipl_t ipl;
size_t pages;
ipl = interrupts_disable();
mutex_lock(&as->lock);
/*
* Locate the area.
*/
area = find_area_and_lock(as, address);
if (!area) {
mutex_unlock(&as->lock);
interrupts_restore(ipl);
return ENOENT;
}
if (area->flags & AS_AREA_DEVICE) {
/*
* Remapping of address space areas associated
* with memory mapped devices is not supported.
*/
mutex_unlock(&area->lock);
mutex_unlock(&as->lock);
interrupts_restore(ipl);
return ENOTSUP;
}
if (area->sh_info) {
/*
* Remapping of shared address space areas
* is not supported.
*/
mutex_unlock(&area->lock);
mutex_unlock(&as->lock);
interrupts_restore(ipl);
return ENOTSUP;
}
pages = SIZE2FRAMES((address - area->base) + size);
if (!pages) {
/*
* Zero size address space areas are not allowed.
*/
mutex_unlock(&area->lock);
mutex_unlock(&as->lock);
interrupts_restore(ipl);
return EPERM;
}
if (pages < area->pages) {
bool cond;
__address start_free = area->base + pages*PAGE_SIZE;
/*
* Shrinking the area.
* No need to check for overlaps.
*/
/*
* Remove frames belonging to used space starting from
* the highest addresses downwards until an overlap with
* the resized address space area is found. Note that this
* is also the right way to remove part of the used_space
* B+tree leaf list.
*/
for (cond = true; cond;) {
btree_node_t *node;
ASSERT(!list_empty(&area->used_space.leaf_head));
node = list_get_instance(area->used_space.leaf_head.prev, btree_node_t, leaf_link);
if ((cond = (bool) node->keys)) {
__address b = node->key[node->keys - 1];
count_t c = (count_t) node->value[node->keys - 1];
int i = 0;
if (overlaps(b, c*PAGE_SIZE, area->base, pages*PAGE_SIZE)) {
if (b + c*PAGE_SIZE <= start_free) {
/*
* The whole interval fits completely
* in the resized address space area.
*/
break;
}
/*
* Part of the interval corresponding to b and c
* overlaps with the resized address space area.
*/
cond = false; /* we are almost done */
i = (start_free - b) >> PAGE_WIDTH;
if (!used_space_remove(area, start_free, c - i))
panic("Could not remove used space.");
} else {
/*
* The interval of used space can be completely removed.
*/
if (!used_space_remove(area, b, c))
panic("Could not remove used space.\n");
}
for (; i < c; i++) {
pte_t *pte;
page_table_lock(as, false);
pte = page_mapping_find(as, b + i*PAGE_SIZE);
ASSERT(pte && PTE_VALID(pte) && PTE_PRESENT(pte));
if (area->backend && area->backend->backend_frame_free) {
area->backend->backend_frame_free(area,
b + i*PAGE_SIZE, PTE_GET_FRAME(pte));
}
page_mapping_remove(as, b + i*PAGE_SIZE);
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)) {
mutex_unlock(&area->lock);
mutex_unlock(&as->lock);
interrupts_restore(ipl);
return EADDRNOTAVAIL;
}
}
area->pages = pages;
mutex_unlock(&area->lock);
mutex_unlock(&as->lock);
interrupts_restore(ipl);
return 0;
}
/** Destroy address space area.
*
* @param as Address space.
* @param address Address withing the area to be deleted.
*
* @return Zero on success or a value from @ref errno.h on failure.
*/
int as_area_destroy(as_t *as, __address address)
{
as_area_t *area;
__address base;
ipl_t ipl;
bool cond;
ipl = interrupts_disable();
mutex_lock(&as->lock);
area = find_area_and_lock(as, address);
if (!area) {
mutex_unlock(&as->lock);
interrupts_restore(ipl);
return ENOENT;
}
base = area->base;
/*
* Visit only the pages mapped by used_space B+tree.
* Note that we must be very careful when walking the tree
* leaf list and removing used space as the leaf list changes
* unpredictibly after each remove. The solution is to actually
* not walk the tree at all, but to remove items from the head
* of the leaf list until there are some keys left.
*/
for (cond = true; cond;) {
btree_node_t *node;
ASSERT(!list_empty(&area->used_space.leaf_head));
node = list_get_instance(area->used_space.leaf_head.next, btree_node_t, leaf_link);
if ((cond = (bool) node->keys)) {
__address b = node->key[0];
count_t i;
pte_t *pte;
for (i = 0; i < (count_t) node->value[0]; i++) {
page_table_lock(as, false);
pte = page_mapping_find(as, b + i*PAGE_SIZE);
ASSERT(pte && PTE_VALID(pte) && PTE_PRESENT(pte));
if (area->backend && area->backend->backend_frame_free) {
area->backend->backend_frame_free(area,
b + i*PAGE_SIZE, PTE_GET_FRAME(pte));
}
page_mapping_remove(as, b + i*PAGE_SIZE);
page_table_unlock(as, false);
}
if (!used_space_remove(area, b, i))
panic("Could not remove used space.\n");
}
}
btree_destroy(&area->used_space);
/*
* Invalidate TLB's.
*/
tlb_shootdown_start(TLB_INVL_PAGES, AS->asid, area->base, area->pages);
tlb_invalidate_pages(AS->asid, area->base, area->pages);
tlb_shootdown_finalize();
area->attributes |= AS_AREA_ATTR_PARTIAL;
if (area->sh_info)
sh_info_remove_reference(area->sh_info);
mutex_unlock(&area->lock);
/*
* Remove the empty area from address space.
*/
btree_remove(&AS->as_area_btree, base, NULL);
free(area);
mutex_unlock(&AS->lock);
interrupts_restore(ipl);
return 0;
}
/** Steal address space area from another task.
*
* Address space area is stolen from another task
* Moreover, any existing mapping
* is copied as well, providing thus a mechanism
* for sharing group of pages. The source address
* space area and any associated mapping is preserved.
*
* @param src_task Pointer of source task
* @param src_base Base address of the source address space area.
* @param acc_size Expected size of the source area
* @param dst_base Target base address
*
* @return Zero on success or ENOENT if there is no such task or
* if there is no such address space area,
* EPERM if there was a problem in accepting the area or
* ENOMEM if there was a problem in allocating destination
* address space area.
*/
int as_area_steal(task_t *src_task, __address src_base, size_t acc_size,
__address dst_base)
{
ipl_t ipl;
count_t i;
as_t *src_as;
int src_flags;
size_t src_size;
as_area_t *src_area, *dst_area;
ipl = interrupts_disable();
spinlock_lock(&src_task->lock);
src_as = src_task->as;
mutex_lock(&src_as->lock);
src_area = find_area_and_lock(src_as, src_base);
if (!src_area) {
/*
* Could not find the source address space area.
*/
spinlock_unlock(&src_task->lock);
mutex_unlock(&src_as->lock);
interrupts_restore(ipl);
return ENOENT;
}
src_size = src_area->pages * PAGE_SIZE;
src_flags = src_area->flags;
mutex_unlock(&src_area->lock);
mutex_unlock(&src_as->lock);
if (src_size != acc_size) {
spinlock_unlock(&src_task->lock);
interrupts_restore(ipl);
return EPERM;
}
/*
* Create copy of the source address space area.
* The destination area is created with AS_AREA_ATTR_PARTIAL
* attribute set which prevents race condition with
* preliminary as_page_fault() calls.
*/
dst_area = as_area_create(AS, src_flags, src_size, dst_base, AS_AREA_ATTR_PARTIAL, &anon_backend, NULL);
if (!dst_area) {
/*
* Destination address space area could not be created.
*/
spinlock_unlock(&src_task->lock);
interrupts_restore(ipl);
return ENOMEM;
}
spinlock_unlock(&src_task->lock);
/*
* Avoid deadlock by first locking the address space with lower address.
*/
if (AS < src_as) {
mutex_lock(&AS->lock);
mutex_lock(&src_as->lock);
} else {
mutex_lock(&AS->lock);
mutex_lock(&src_as->lock);
}
for (i = 0; i < SIZE2FRAMES(src_size); i++) {
pte_t *pte;
__address frame;
page_table_lock(src_as, false);
pte = page_mapping_find(src_as, src_base + i*PAGE_SIZE);
if (pte && PTE_VALID(pte)) {
ASSERT(PTE_PRESENT(pte));
frame = PTE_GET_FRAME(pte);
if (!(src_flags & AS_AREA_DEVICE))
frame_reference_add(ADDR2PFN(frame));
page_table_unlock(src_as, false);
} else {
page_table_unlock(src_as, false);
continue;
}
page_table_lock(AS, false);
page_mapping_insert(AS, dst_base + i*PAGE_SIZE, frame, area_flags_to_page_flags(src_flags));
page_table_unlock(AS, false);
}
/*
* Now the destination address space area has been
* fully initialized. Clear the AS_AREA_ATTR_PARTIAL
* attribute.
*/
mutex_lock(&dst_area->lock);
dst_area->attributes &= ~AS_AREA_ATTR_PARTIAL;
mutex_unlock(&dst_area->lock);
mutex_unlock(&AS->lock);
mutex_unlock(&src_as->lock);
interrupts_restore(ipl);
return 0;
}
/** 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");
}
ASSERT(!area->backend);
page_mapping_insert(as, page, frame, as_area_get_flags(area));
if (!used_space_insert(area, page, 1))
panic("Could not insert used space.\n");
mutex_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. It decides
* whether the page fault can be resolved by any backend
* and if so, it invokes the backend to resolve the page
* fault.
*
* Interrupts are assumed disabled.
*
* @param page Faulting page.
* @param access Access mode that caused the fault (i.e. read/write/exec).
* @param istate Pointer to interrupted state.
*
* @return AS_PF_FAULT on page fault, AS_PF_OK on success or AS_PF_DEFER if the
* fault was caused by copy_to_uspace() or copy_from_uspace().
*/
int as_page_fault(__address page, pf_access_t access, istate_t *istate)
{
pte_t *pte;
as_area_t *area;
if (!THREAD)
return AS_PF_FAULT;
ASSERT(AS);
mutex_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.
*/
mutex_unlock(&AS->lock);
goto page_fault;
}
if (area->attributes & AS_AREA_ATTR_PARTIAL) {
/*
* The address space area is not fully initialized.
* Avoid possible race by returning error.
*/
mutex_unlock(&area->lock);
mutex_unlock(&AS->lock);
goto page_fault;
}
if (!area->backend || !area->backend->backend_page_fault) {
/*
* The address space area is not backed by any backend
* or the backend cannot handle page faults.
*/
mutex_unlock(&area->lock);
mutex_unlock(&AS->lock);
goto page_fault;
}
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);
mutex_unlock(&area->lock);
mutex_unlock(&AS->lock);
return AS_PF_OK;
}
}
/*
* Resort to the backend page fault handler.
*/
if (area->backend->backend_page_fault(area, page, access) != AS_PF_OK) {
page_table_unlock(AS, false);
mutex_unlock(&area->lock);
mutex_unlock(&AS->lock);
goto page_fault;
}
page_table_unlock(AS, false);
mutex_unlock(&area->lock);
mutex_unlock(&AS->lock);
return AS_PF_OK;
page_fault:
if (THREAD->in_copy_from_uspace) {
THREAD->in_copy_from_uspace = false;
istate_set_retaddr(istate, (__address) &memcpy_from_uspace_failover_address);
} else if (THREAD->in_copy_to_uspace) {
THREAD->in_copy_to_uspace = false;
istate_set_retaddr(istate, (__address) &memcpy_to_uspace_failover_address);
} else {
return AS_PF_FAULT;
}
return AS_PF_DEFER;
}
/** Switch address spaces.
*
* Note that this function cannot sleep as it is essentially a part of
* the scheduling. Sleeping here would lead to deadlock on wakeup.
*
* @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) {
mutex_lock_active(&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);
}
mutex_unlock(&old->lock);
}
/*
* Second, prepare the new address space.
*/
mutex_lock_active(&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);
mutex_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();
mutex_lock_active(&new->lock);
new->asid = asid;
mutex_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;
}
/** Convert address space area flags to page flags.
*
* @param aflags Flags of some address space area.
*
* @return Flags to be passed to page_mapping_insert().
*/
int area_flags_to_page_flags(int aflags)
{
int flags;
flags = PAGE_USER | PAGE_PRESENT;
if (aflags & AS_AREA_READ)
flags |= PAGE_READ;
if (aflags & AS_AREA_WRITE)
flags |= PAGE_WRITE;
if (aflags & AS_AREA_EXEC)
flags |= PAGE_EXEC;
if (!(aflags & AS_AREA_DEVICE))
flags |= PAGE_CACHEABLE;
return flags;
}
/** 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 as_area_get_flags(as_area_t *a)
{
return area_flags_to_page_flags(a->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 lock 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 unlock 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 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 */
mutex_lock(&a->lock);
return a;
}
/*
* Search the leaf node and the righmost record of its left neighbour
* 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];
mutex_lock(&a->lock);
if ((a->base <= va) && (va < a->base + a->pages * PAGE_SIZE)) {
return a;
}
mutex_unlock(&a->lock);
}
/*
* Second, locate the left neighbour and test its last record.
* Because of its position in the B+tree, it must have base < va.
*/
if ((lnode = btree_leaf_node_left_neighbour(&as->as_area_btree, leaf))) {
a = (as_area_t *) lnode->value[lnode->keys - 1];
mutex_lock(&a->lock);
if (va < a->base + a->pages * PAGE_SIZE) {
return a;
}
mutex_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 neighbour, the leftmost record in the right
* neighbour 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_leaf_node_left_neighbour(&as->as_area_btree, leaf))) {
a = (as_area_t *) node->value[node->keys - 1];
mutex_lock(&a->lock);
if (overlaps(va, size, a->base, a->pages * PAGE_SIZE)) {
mutex_unlock(&a->lock);
return false;
}
mutex_unlock(&a->lock);
}
if ((node = btree_leaf_node_right_neighbour(&as->as_area_btree, leaf))) {
a = (as_area_t *) node->value[0];
mutex_lock(&a->lock);
if (overlaps(va, size, a->base, a->pages * PAGE_SIZE)) {
mutex_unlock(&a->lock);
return false;
}
mutex_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;
mutex_lock(&a->lock);
if (overlaps(va, size, a->base, a->pages * PAGE_SIZE)) {
mutex_unlock(&a->lock);
return false;
}
mutex_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;
}
/** Return size of the address space area with given base. */
size_t as_get_size(__address base)
{
ipl_t ipl;
as_area_t *src_area;
size_t size;
ipl = interrupts_disable();
src_area = find_area_and_lock(AS, base);
if (src_area){
size = src_area->pages * PAGE_SIZE;
mutex_unlock(&src_area->lock);
} else {
size = 0;
}
interrupts_restore(ipl);
return size;
}
/** Mark portion of address space area as used.
*
* The address space area must be already locked.
*
* @param a Address space area.
* @param page First page to be marked.
* @param count Number of page to be marked.
*
* @return 0 on failure and 1 on success.
*/
int used_space_insert(as_area_t *a, __address page, count_t count)
{
btree_node_t *leaf, *node;
count_t pages;
int i;
ASSERT(page == ALIGN_DOWN(page, PAGE_SIZE));
ASSERT(count);
pages = (count_t) btree_search(&a->used_space, page, &leaf);
if (pages) {
/*
* We hit the beginning of some used space.
*/
return 0;
}
node = btree_leaf_node_left_neighbour(&a->used_space, leaf);
if (node) {
__address left_pg = node->key[node->keys - 1], right_pg = leaf->key[0];
count_t left_cnt = (count_t) node->value[node->keys - 1], right_cnt = (count_t) leaf->value[0];
/*
* Examine the possibility that the interval fits
* somewhere between the rightmost interval of
* the left neigbour and the first interval of the leaf.
*/
if (page >= right_pg) {
/* Do nothing. */
} else if (overlaps(page, count*PAGE_SIZE, left_pg, left_cnt*PAGE_SIZE)) {
/* The interval intersects with the left interval. */
return 0;
} else if (overlaps(page, count*PAGE_SIZE, right_pg, right_cnt*PAGE_SIZE)) {
/* The interval intersects with the right interval. */
return 0;
} else if ((page == left_pg + left_cnt*PAGE_SIZE) && (page + count*PAGE_SIZE == right_pg)) {
/* The interval can be added by merging the two already present intervals. */
node->value[node->keys - 1] += count + right_cnt;
btree_remove(&a->used_space, right_pg, leaf);
return 1;
} else if (page == left_pg + left_cnt*PAGE_SIZE) {
/* The interval can be added by simply growing the left interval. */
node->value[node->keys - 1] += count;
return 1;
} else if (page + count*PAGE_SIZE == right_pg) {
/*
* The interval can be addded by simply moving base of the right
* interval down and increasing its size accordingly.
*/
leaf->value[0] += count;
leaf->key[0] = page;
return 1;
} else {
/*
* The interval is between both neigbouring intervals,
* but cannot be merged with any of them.
*/
btree_insert(&a->used_space, page, (void *) count, leaf);
return 1;
}
} else if (page < leaf->key[0]) {
__address right_pg = leaf->key[0];
count_t right_cnt = (count_t) leaf->value[0];
/*
* Investigate the border case in which the left neighbour does not
* exist but the interval fits from the left.
*/
if (overlaps(page, count*PAGE_SIZE, right_pg, right_cnt*PAGE_SIZE)) {
/* The interval intersects with the right interval. */
return 0;
} else if (page + count*PAGE_SIZE == right_pg) {
/*
* The interval can be added by moving the base of the right interval down
* and increasing its size accordingly.
*/
leaf->key[0] = page;
leaf->value[0] += count;
return 1;
} else {
/*
* The interval doesn't adjoin with the right interval.
* It must be added individually.
*/
btree_insert(&a->used_space, page, (void *) count, leaf);
return 1;
}
}
node = btree_leaf_node_right_neighbour(&a->used_space, leaf);
if (node) {
__address left_pg = leaf->key[leaf->keys - 1], right_pg = node->key[0];
count_t left_cnt = (count_t) leaf->value[leaf->keys - 1], right_cnt = (count_t) node->value[0];
/*
* Examine the possibility that the interval fits
* somewhere between the leftmost interval of
* the right neigbour and the last interval of the leaf.
*/
if (page < left_pg) {
/* Do nothing. */
} else if (overlaps(page, count*PAGE_SIZE, left_pg, left_cnt*PAGE_SIZE)) {
/* The interval intersects with the left interval. */
return 0;
} else if (overlaps(page, count*PAGE_SIZE, right_pg, right_cnt*PAGE_SIZE)) {
/* The interval intersects with the right interval. */
return 0;
} else if ((page == left_pg + left_cnt*PAGE_SIZE) && (page + count*PAGE_SIZE == right_pg)) {
/* The interval can be added by merging the two already present intervals. */
leaf->value[leaf->keys - 1] += count + right_cnt;
btree_remove(&a->used_space, right_pg, node);
return 1;
} else if (page == left_pg + left_cnt*PAGE_SIZE) {
/* The interval can be added by simply growing the left interval. */
leaf->value[leaf->keys - 1] += count;
return 1;
} else if (page + count*PAGE_SIZE == right_pg) {
/*
* The interval can be addded by simply moving base of the right
* interval down and increasing its size accordingly.
*/
node->value[0] += count;
node->key[0] = page;
return 1;
} else {
/*
* The interval is between both neigbouring intervals,
* but cannot be merged with any of them.
*/
btree_insert(&a->used_space, page, (void *) count, leaf);
return 1;
}
} else if (page >= leaf->key[leaf->keys - 1]) {
__address left_pg = leaf->key[leaf->keys - 1];
count_t left_cnt = (count_t) leaf->value[leaf->keys - 1];
/*
* Investigate the border case in which the right neighbour does not
* exist but the interval fits from the right.
*/
if (overlaps(page, count*PAGE_SIZE, left_pg, left_cnt*PAGE_SIZE)) {
/* The interval intersects with the left interval. */
return 0;
} else if (left_pg + left_cnt*PAGE_SIZE == page) {
/* The interval can be added by growing the left interval. */
leaf->value[leaf->keys - 1] += count;
return 1;
} else {
/*
* The interval doesn't adjoin with the left interval.
* It must be added individually.
*/
btree_insert(&a->used_space, page, (void *) count, leaf);
return 1;
}
}
/*
* Note that if the algorithm made it thus far, the interval can fit only
* between two other intervals of the leaf. The two border cases were already
* resolved.
*/
for (i = 1; i < leaf->keys; i++) {
if (page < leaf->key[i]) {
__address left_pg = leaf->key[i - 1], right_pg = leaf->key[i];
count_t left_cnt = (count_t) leaf->value[i - 1], right_cnt = (count_t) leaf->value[i];
/*
* The interval fits between left_pg and right_pg.
*/
if (overlaps(page, count*PAGE_SIZE, left_pg, left_cnt*PAGE_SIZE)) {
/* The interval intersects with the left interval. */
return 0;
} else if (overlaps(page, count*PAGE_SIZE, right_pg, right_cnt*PAGE_SIZE)) {
/* The interval intersects with the right interval. */
return 0;
} else if ((page == left_pg + left_cnt*PAGE_SIZE) && (page + count*PAGE_SIZE == right_pg)) {
/* The interval can be added by merging the two already present intervals. */
leaf->value[i - 1] += count + right_cnt;
btree_remove(&a->used_space, right_pg, leaf);
return 1;
} else if (page == left_pg + left_cnt*PAGE_SIZE) {
/* The interval can be added by simply growing the left interval. */
leaf->value[i - 1] += count;
return 1;
} else if (page + count*PAGE_SIZE == right_pg) {
/*
* The interval can be addded by simply moving base of the right
* interval down and increasing its size accordingly.
*/
leaf->value[i] += count;
leaf->key[i] = page;
return 1;
} else {
/*
* The interval is between both neigbouring intervals,
* but cannot be merged with any of them.
*/
btree_insert(&a->used_space, page, (void *) count, leaf);
return 1;
}
}
}
panic("Inconsistency detected while adding %d pages of used space at %P.\n", count, page);
}
/** Mark portion of address space area as unused.
*
* The address space area must be already locked.
*
* @param a Address space area.
* @param page First page to be marked.
* @param count Number of page to be marked.
*
* @return 0 on failure and 1 on success.
*/
int used_space_remove(as_area_t *a, __address page, count_t count)
{
btree_node_t *leaf, *node;
count_t pages;
int i;
ASSERT(page == ALIGN_DOWN(page, PAGE_SIZE));
ASSERT(count);
pages = (count_t) btree_search(&a->used_space, page, &leaf);
if (pages) {
/*
* We are lucky, page is the beginning of some interval.
*/
if (count > pages) {
return 0;
} else if (count == pages) {
btree_remove(&a->used_space, page, leaf);
return 1;
} else {
/*
* Find the respective interval.
* Decrease its size and relocate its start address.
*/
for (i = 0; i < leaf->keys; i++) {
if (leaf->key[i] == page) {
leaf->key[i] += count*PAGE_SIZE;
leaf->value[i] -= count;
return 1;
}
}
goto error;
}
}
node = btree_leaf_node_left_neighbour(&a->used_space, leaf);
if (node && page < leaf->key[0]) {
__address left_pg = node->key[node->keys - 1];
count_t left_cnt = (count_t) node->value[node->keys - 1];
if (overlaps(left_pg, left_cnt*PAGE_SIZE, page, count*PAGE_SIZE)) {
if (page + count*PAGE_SIZE == left_pg + left_cnt*PAGE_SIZE) {
/*
* The interval is contained in the rightmost interval
* of the left neighbour and can be removed by
* updating the size of the bigger interval.
*/
node->value[node->keys - 1] -= count;
return 1;
} else if (page + count*PAGE_SIZE < left_pg + left_cnt*PAGE_SIZE) {
count_t new_cnt;
/*
* The interval is contained in the rightmost interval
* of the left neighbour but its removal requires
* both updating the size of the original interval and
* also inserting a new interval.
*/
new_cnt = ((left_pg + left_cnt*PAGE_SIZE) - (page + count*PAGE_SIZE)) >> PAGE_WIDTH;
node->value[node->keys - 1] -= count + new_cnt;
btree_insert(&a->used_space, page + count*PAGE_SIZE, (void *) new_cnt, leaf);
return 1;
}
}
return 0;
} else if (page < leaf->key[0]) {
return 0;
}
if (page > leaf->key[leaf->keys - 1]) {
__address left_pg = leaf->key[leaf->keys - 1];
count_t left_cnt = (count_t) leaf->value[leaf->keys - 1];
if (overlaps(left_pg, left_cnt*PAGE_SIZE, page, count*PAGE_SIZE)) {
if (page + count*PAGE_SIZE == left_pg + left_cnt*PAGE_SIZE) {
/*
* The interval is contained in the rightmost interval
* of the leaf and can be removed by updating the size
* of the bigger interval.
*/
leaf->value[leaf->keys - 1] -= count;
return 1;
} else if (page + count*PAGE_SIZE < left_pg + left_cnt*PAGE_SIZE) {
count_t new_cnt;
/*
* The interval is contained in the rightmost interval
* of the leaf but its removal requires both updating
* the size of the original interval and
* also inserting a new interval.
*/
new_cnt = ((left_pg + left_cnt*PAGE_SIZE) - (page + count*PAGE_SIZE)) >> PAGE_WIDTH;
leaf->value[leaf->keys - 1] -= count + new_cnt;
btree_insert(&a->used_space, page + count*PAGE_SIZE, (void *) new_cnt, leaf);
return 1;
}
}
return 0;
}
/*
* The border cases have been already resolved.
* Now the interval can be only between intervals of the leaf.
*/
for (i = 1; i < leaf->keys - 1; i++) {
if (page < leaf->key[i]) {
__address left_pg = leaf->key[i - 1];
count_t left_cnt = (count_t) leaf->value[i - 1];
/*
* Now the interval is between intervals corresponding to (i - 1) and i.
*/
if (overlaps(left_pg, left_cnt*PAGE_SIZE, page, count*PAGE_SIZE)) {
if (page + count*PAGE_SIZE == left_pg + left_cnt*PAGE_SIZE) {
/*
* The interval is contained in the interval (i - 1)
* of the leaf and can be removed by updating the size
* of the bigger interval.
*/
leaf->value[i - 1] -= count;
return 1;
} else if (page + count*PAGE_SIZE < left_pg + left_cnt*PAGE_SIZE) {
count_t new_cnt;
/*
* The interval is contained in the interval (i - 1)
* of the leaf but its removal requires both updating
* the size of the original interval and
* also inserting a new interval.
*/
new_cnt = ((left_pg + left_cnt*PAGE_SIZE) - (page + count*PAGE_SIZE)) >> PAGE_WIDTH;
leaf->value[i - 1] -= count + new_cnt;
btree_insert(&a->used_space, page + count*PAGE_SIZE, (void *) new_cnt, leaf);
return 1;
}
}
return 0;
}
}
error:
panic("Inconsistency detected while removing %d pages of used space from %P.\n", count, page);
}
/** Remove reference to address space area share info.
*
* If the reference count drops to 0, the sh_info is deallocated.
*
* @param sh_info Pointer to address space area share info.
*/
void sh_info_remove_reference(share_info_t *sh_info)
{
bool dealloc = false;
mutex_lock(&sh_info->lock);
ASSERT(sh_info->refcount);
if (--sh_info->refcount == 0) {
dealloc = true;
bool cond;
/*
* Now walk carefully the pagemap B+tree and free/remove
* reference from all frames found there.
*/
for (cond = true; cond;) {
btree_node_t *node;
ASSERT(!list_empty(&sh_info->pagemap.leaf_head));
node = list_get_instance(sh_info->pagemap.leaf_head.next, btree_node_t, leaf_link);
if ((cond = node->keys)) {
frame_free(ADDR2PFN((__address) node->value[0]));
btree_remove(&sh_info->pagemap, node->key[0], node);
}
}
}
mutex_unlock(&sh_info->lock);
if (dealloc) {
btree_destroy(&sh_info->pagemap);
free(sh_info);
}
}
static int anon_page_fault(as_area_t *area, __address addr, pf_access_t access);
static void anon_frame_free(as_area_t *area, __address page, __address frame);
/*
* Anonymous memory backend.
*/
mem_backend_t anon_backend = {
.backend_page_fault = anon_page_fault,
.backend_frame_free = anon_frame_free
};
/** Service a page fault in the anonymous memory address space area.
*
* The address space area and page tables must be already locked.
*
* @param area Pointer to the address space area.
* @param addr Faulting virtual address.
* @param access Access mode that caused the fault (i.e. read/write/exec).
*
* @return AS_PF_FAULT on failure (i.e. page fault) or AS_PF_OK on success (i.e. serviced).
*/
int anon_page_fault(as_area_t *area, __address addr, pf_access_t access)
{
__address frame;
if (area->sh_info) {
btree_node_t *leaf;
/*
* The area is shared, chances are that the mapping can be found
* in the pagemap of the address space area share info structure.
* In the case that the pagemap does not contain the respective
* mapping, a new frame is allocated and the mapping is created.
*/
mutex_lock(&area->sh_info->lock);
frame = (__address) btree_search(&area->sh_info->pagemap, ALIGN_DOWN(addr, PAGE_SIZE), &leaf);
if (!frame) {
bool allocate = true;
int i;
/*
* Zero can be returned as a valid frame address.
* Just a small workaround.
*/
for (i = 0; i < leaf->keys; i++) {
if (leaf->key[i] == ALIGN_DOWN(addr, PAGE_SIZE)) {
allocate = false;
break;
}
}
if (allocate) {
frame = PFN2ADDR(frame_alloc(ONE_FRAME, 0));
memsetb(PA2KA(frame), FRAME_SIZE, 0);
/*
* Insert the address of the newly allocated frame to the pagemap.
*/
btree_insert(&area->sh_info->pagemap, ALIGN_DOWN(addr, PAGE_SIZE), (void *) frame, leaf);
}
}
mutex_unlock(&area->sh_info->lock);
} else {
/*
* In general, there can be several reasons that
* can have caused this fault.
*
* - non-existent mapping: the area is an anonymous
* area (e.g. heap or 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, addr, frame, as_area_get_flags(area));
if (!used_space_insert(area, ALIGN_DOWN(addr, PAGE_SIZE), 1))
panic("Could not insert used space.\n");
return AS_PF_OK;
}
/** Free a frame that is backed by the anonymous memory backend.
*
* The address space area and page tables must be already locked.
*
* @param area Ignored.
* @param page Ignored.
* @param frame Frame to be released.
*/
void anon_frame_free(as_area_t *area, __address page, __address frame)
{
frame_free(ADDR2PFN(frame));
}
/*
* Address space related syscalls.
*/
/** Wrapper for as_area_create(). */
__native sys_as_area_create(__address address, size_t size, int flags)
{
if (as_area_create(AS, flags, size, address, AS_AREA_ATTR_NONE, &anon_backend, NULL))
return (__native) address;
else
return (__native) -1;
}
/** Wrapper for as_area_resize. */
__native sys_as_area_resize(__address address, size_t size, int flags)
{
return (__native) as_area_resize(AS, address, size, 0);
}
/** Wrapper for as_area_destroy. */
__native sys_as_area_destroy(__address address)
{
return (__native) as_area_destroy(AS, address);
}