/*
* 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.
*/
/** @addtogroup genericmm
* @{
*/
/**
* @file
* @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 spaces 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 <preemption.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 <syscall/copy.h>
#include <arch/interrupt.h>
#ifdef CONFIG_VIRT_IDX_DCACHE
#include <arch/mm/cache.h>
#endif /* CONFIG_VIRT_IDX_DCACHE */
/**
* Each architecture decides what functions will be used to carry out
* address space operations such as creating or locking page tables.
*/
as_operations_t *as_operations = NULL;
/**
* Slab for as_t objects.
*/
static slab_cache_t *as_slab;
/**
* This lock serializes access to the ASID subsystem.
* It protects:
* - inactive_as_with_asid_head list
* - as->asid for each as of the as_t type
* - asids_allocated counter
*/
SPINLOCK_INITIALIZE(asidlock);
/**
* 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);
static as_area_t *find_area_and_lock(as_t *, uintptr_t);
static bool check_area_conflicts(as_t *, uintptr_t, size_t, as_area_t *);
static void sh_info_remove_reference(share_info_t *);
static int as_constructor(void *obj, int flags)
{
as_t *as = (as_t *) obj;
int rc;
link_initialize(&as->inactive_as_with_asid_link);
mutex_initialize(&as->lock, MUTEX_PASSIVE);
rc = as_constructor_arch(as, flags);
return rc;
}
static int as_destructor(void *obj)
{
as_t *as = (as_t *) obj;
return as_destructor_arch(as);
}
/** Initialize address space subsystem. */
void as_init(void)
{
as_arch_init();
as_slab = slab_cache_create("as_slab", sizeof(as_t), 0,
as_constructor, as_destructor, SLAB_CACHE_MAGDEFERRED);
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 the way in wich the address space
* is created.
*/
as_t *as_create(int flags)
{
as_t *as;
as = (as_t *) slab_alloc(as_slab, 0);
(void) as_create_arch(as, 0);
btree_create(&as->as_area_btree);
if (flags & FLAG_AS_KERNEL)
as->asid = ASID_KERNEL;
else
as->asid = ASID_INVALID;
atomic_set(&as->refcount, 0);
as->cpu_refcount = 0;
#ifdef AS_PAGE_TABLE
as->genarch.page_table = page_table_create(flags);
#else
page_table_create(flags);
#endif
return as;
}
/** Destroy adress space.
*
* When there are no tasks referencing this address space (i.e. its refcount is
* zero), the address space can be destroyed.
*
* We know that we don't hold any spinlock.
*
* @param as Address space to be destroyed.
*/
void as_destroy(as_t *as)
{
ipl_t ipl;
bool cond;
DEADLOCK_PROBE_INIT(p_asidlock);
ASSERT(atomic_get(&as->refcount) == 0);
/*
* Since there is no reference to this area,
* it is safe not to lock its mutex.
*/
/*
* We need to avoid deadlock between TLB shootdown and asidlock.
* We therefore try to take asid conditionally and if we don't succeed,
* we enable interrupts and try again. This is done while preemption is
* disabled to prevent nested context switches. We also depend on the
* fact that so far no spinlocks are held.
*/
preemption_disable();
ipl = interrupts_read();
retry:
interrupts_disable();
if (!spinlock_trylock(&asidlock)) {
interrupts_enable();
DEADLOCK_PROBE(p_asidlock, DEADLOCK_THRESHOLD);
goto retry;
}
preemption_enable(); /* Interrupts disabled, enable preemption */
if (as->asid != ASID_INVALID && as != AS_KERNEL) {
if (as != AS && as->cpu_refcount == 0)
list_remove(&as->inactive_as_with_asid_link);
asid_put(as->asid);
}
spinlock_unlock(&asidlock);
/*
* Destroy address space areas of the address space.
* The B+tree must be walked carefully because it is
* also being destroyed.
*/
for (cond = true; cond; ) {
btree_node_t *node;
ASSERT(!list_empty(&as->as_area_btree.leaf_head));
node = list_get_instance(as->as_area_btree.leaf_head.next,
btree_node_t, leaf_link);
if ((cond = node->keys)) {
as_area_destroy(as, node->key[0]);
}
}
btree_destroy(&as->as_area_btree);
#ifdef AS_PAGE_TABLE
page_table_destroy(as->genarch.page_table);
#else
page_table_destroy(NULL);
#endif
interrupts_restore(ipl);
slab_free(as_slab, 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, uintptr_t base, int attrs,
mem_backend_t *backend, mem_backend_data_t *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, MUTEX_PASSIVE);
a->as = as;
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 = *backend_data;
else
memsetb(&a->backend_data, sizeof(a->backend_data), 0);
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, uintptr_t 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->backend == &phys_backend) {
/*
* 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;
uintptr_t start_free = area->base + pages * PAGE_SIZE;
/*
* Shrinking the area.
* No need to check for overlaps.
*/
/*
* Start TLB shootdown sequence.
*/
tlb_shootdown_start(TLB_INVL_PAGES, as->asid, area->base +
pages * PAGE_SIZE, area->pages - pages);
/*
* 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)) {
uintptr_t b = node->key[node->keys - 1];
count_t c =
(count_t) node->value[node->keys - 1];
unsigned 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.\n");
} 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->frame_free) {
area->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);
}
}
}
/*
* Finish TLB shootdown sequence.
*/
tlb_invalidate_pages(as->asid, area->base + pages * PAGE_SIZE,
area->pages - pages);
/*
* Invalidate software translation caches (e.g. TSB on sparc64).
*/
as_invalidate_translation_cache(as, 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 within 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, uintptr_t address)
{
as_area_t *area;
uintptr_t base;
link_t *cur;
ipl_t ipl;
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;
/*
* Start TLB shootdown sequence.
*/
tlb_shootdown_start(TLB_INVL_PAGES, as->asid, area->base, area->pages);
/*
* Visit only the pages mapped by used_space B+tree.
*/
for (cur = area->used_space.leaf_head.next;
cur != &area->used_space.leaf_head; cur = cur->next) {
btree_node_t *node;
unsigned int i;
node = list_get_instance(cur, btree_node_t, leaf_link);
for (i = 0; i < node->keys; i++) {
uintptr_t b = node->key[i];
count_t j;
pte_t *pte;
for (j = 0; j < (count_t) node->value[i]; j++) {
page_table_lock(as, false);
pte = page_mapping_find(as, b + j * PAGE_SIZE);
ASSERT(pte && PTE_VALID(pte) &&
PTE_PRESENT(pte));
if (area->backend &&
area->backend->frame_free) {
area->backend->frame_free(area, b +
j * PAGE_SIZE, PTE_GET_FRAME(pte));
}
page_mapping_remove(as, b + j * PAGE_SIZE);
page_table_unlock(as, false);
}
}
}
/*
* Finish TLB shootdown sequence.
*/
tlb_invalidate_pages(as->asid, area->base, area->pages);
/*
* Invalidate potential software translation caches (e.g. TSB on
* sparc64).
*/
as_invalidate_translation_cache(as, area->base, area->pages);
tlb_shootdown_finalize();
btree_destroy(&area->used_space);
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);
mutex_unlock(&as->lock);
interrupts_restore(ipl);
return 0;
}
/** Share address space area with another or the same address space.
*
* Address space area mapping is shared with a new address space area.
* If the source address space area has not been shared so far,
* a new sh_info is created. The new address space area simply gets the
* sh_info of the source area. The process of duplicating the
* mapping is done through the backend share function.
*
* @param src_as Pointer to source address space.
* @param src_base Base address of the source address space area.
* @param acc_size Expected size of the source area.
* @param dst_as Pointer to destination address space.
* @param dst_base Target base address.
* @param dst_flags_mask Destination address space area flags mask.
*
* @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.
* ENOTSUP is returned if the address space area backend
* does not support sharing.
*/
int as_area_share(as_t *src_as, uintptr_t src_base, size_t acc_size,
as_t *dst_as, uintptr_t dst_base, int dst_flags_mask)
{
ipl_t ipl;
int src_flags;
size_t src_size;
as_area_t *src_area, *dst_area;
share_info_t *sh_info;
mem_backend_t *src_backend;
mem_backend_data_t src_backend_data;
ipl = interrupts_disable();
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.
*/
mutex_unlock(&src_as->lock);
interrupts_restore(ipl);
return ENOENT;
}
if (!src_area->backend || !src_area->backend->share) {
/*
* There is no backend or the backend does not
* know how to share the area.
*/
mutex_unlock(&src_area->lock);
mutex_unlock(&src_as->lock);
interrupts_restore(ipl);
return ENOTSUP;
}
src_size = src_area->pages * PAGE_SIZE;
src_flags = src_area->flags;
src_backend = src_area->backend;
src_backend_data = src_area->backend_data;
/* Share the cacheable flag from the original mapping */
if (src_flags & AS_AREA_CACHEABLE)
dst_flags_mask |= AS_AREA_CACHEABLE;
if (src_size != acc_size ||
(src_flags & dst_flags_mask) != dst_flags_mask) {
mutex_unlock(&src_area->lock);
mutex_unlock(&src_as->lock);
interrupts_restore(ipl);
return EPERM;
}
/*
* Now we are committed to sharing the area.
* First, prepare the area for sharing.
* Then it will be safe to unlock it.
*/
sh_info = src_area->sh_info;
if (!sh_info) {
sh_info
= (share_info_t
*) malloc(sizeof(share_info_t
), 0); mutex_initialize(&sh_info->lock, MUTEX_PASSIVE);
sh_info->refcount = 2;
btree_create(&sh_info->pagemap);
src_area->sh_info = sh_info;
/*
* Call the backend to setup sharing.
*/
src_area->backend->share(src_area);
} else {
mutex_lock(&sh_info->lock);
sh_info->refcount++;
mutex_unlock(&sh_info->lock);
}
mutex_unlock(&src_area->lock);
mutex_unlock(&src_as->lock);
/*
* 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.
* The flags of the source area are masked against dst_flags_mask
* to support sharing in less privileged mode.
*/
dst_area = as_area_create(dst_as, dst_flags_mask, src_size, dst_base,
AS_AREA_ATTR_PARTIAL, src_backend, &src_backend_data);
if (!dst_area) {
/*
* Destination address space area could not be created.
*/
sh_info_remove_reference(sh_info);
interrupts_restore(ipl);
return ENOMEM;
}
/*
* Now the destination address space area has been
* fully initialized. Clear the AS_AREA_ATTR_PARTIAL
* attribute and set the sh_info.
*/
mutex_lock(&dst_as->lock);
mutex_lock(&dst_area->lock);
dst_area->attributes &= ~AS_AREA_ATTR_PARTIAL;
dst_area->sh_info = sh_info;
mutex_unlock(&dst_area->lock);
mutex_unlock(&dst_as->lock);
interrupts_restore(ipl);
return 0;
}
/** Check access mode for address space area.
*
* The address space area must be locked prior to this call.
*
* @param area Address space area.
* @param access Access mode.
*
* @return False if access violates area's permissions, true
* otherwise.
*/
bool as_area_check_access(as_area_t *area, pf_access_t access)
{
int flagmap[] = {
[PF_ACCESS_READ] = AS_AREA_READ,
[PF_ACCESS_WRITE] = AS_AREA_WRITE,
[PF_ACCESS_EXEC] = AS_AREA_EXEC
};
if (!(area->flags & flagmap[access]))
return false;
return true;
}
/** Change adress space area flags.
*
* The idea is to have the same data, but with a different access mode.
* This is needed e.g. for writing code into memory and then executing it.
* In order for this to work properly, this may copy the data
* into private anonymous memory (unless it's already there).
*
* @param as Address space.
* @param flags Flags of the area memory.
* @param address Address withing the area to be changed.
*
* @return Zero on success or a value from @ref errno.h on failure.
*/
int as_area_change_flags(as_t *as, int flags, uintptr_t address)
{
as_area_t *area;
uintptr_t base;
link_t *cur;
ipl_t ipl;
int page_flags;
uintptr_t *old_frame;
index_t frame_idx;
count_t used_pages;
/* Flags for the new memory mapping */
page_flags = area_flags_to_page_flags(flags);
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;
}
if (area->sh_info || area->backend != &anon_backend) {
/* Copying shared areas not supported yet */
/* Copying non-anonymous memory not supported yet */
mutex_unlock(&area->lock);
mutex_unlock(&as->lock);
interrupts_restore(ipl);
return ENOTSUP;
}
base = area->base;
/*
* Compute total number of used pages in the used_space B+tree
*/
used_pages = 0;
for (cur = area->used_space.leaf_head.next;
cur != &area->used_space.leaf_head; cur = cur->next) {
btree_node_t *node;
unsigned int i;
node = list_get_instance(cur, btree_node_t, leaf_link);
for (i = 0; i < node->keys; i++) {
used_pages += (count_t) node->value[i];
}
}
/* An array for storing frame numbers */
old_frame
= malloc(used_pages
* sizeof(uintptr_t), 0);
/*
* Start TLB shootdown sequence.
*/
tlb_shootdown_start(TLB_INVL_PAGES, as->asid, area->base, area->pages);
/*
* Remove used pages from page tables and remember their frame
* numbers.
*/
frame_idx = 0;
for (cur = area->used_space.leaf_head.next;
cur != &area->used_space.leaf_head; cur = cur->next) {
btree_node_t *node;
unsigned int i;
node = list_get_instance(cur, btree_node_t, leaf_link);
for (i = 0; i < node->keys; i++) {
uintptr_t b = node->key[i];
count_t j;
pte_t *pte;
for (j = 0; j < (count_t) node->value[i]; j++) {
page_table_lock(as, false);
pte = page_mapping_find(as, b + j * PAGE_SIZE);
ASSERT(pte && PTE_VALID(pte) &&
PTE_PRESENT(pte));
old_frame[frame_idx++] = PTE_GET_FRAME(pte);
/* Remove old mapping */
page_mapping_remove(as, b + j * PAGE_SIZE);
page_table_unlock(as, false);
}
}
}
/*
* Finish TLB shootdown sequence.
*/
tlb_invalidate_pages(as->asid, area->base, area->pages);
/*
* Invalidate potential software translation caches (e.g. TSB on
* sparc64).
*/
as_invalidate_translation_cache(as, area->base, area->pages);
tlb_shootdown_finalize();
/*
* Set the new flags.
*/
area->flags = flags;
/*
* Map pages back in with new flags. This step is kept separate
* so that the memory area could not be accesed with both the old and
* the new flags at once.
*/
frame_idx = 0;
for (cur = area->used_space.leaf_head.next;
cur != &area->used_space.leaf_head; cur = cur->next) {
btree_node_t *node;
unsigned int i;
node = list_get_instance(cur, btree_node_t, leaf_link);
for (i = 0; i < node->keys; i++) {
uintptr_t b = node->key[i];
count_t j;
for (j = 0; j < (count_t) node->value[i]; j++) {
page_table_lock(as, false);
/* Insert the new mapping */
page_mapping_insert(as, b + j * PAGE_SIZE,
old_frame[frame_idx++], page_flags);
page_table_unlock(as, false);
}
}
}
mutex_unlock(&area->lock);
mutex_unlock(&as->lock);
interrupts_restore(ipl);
return 0;
}
/** 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 page fault (i.e.
* read/write/exec).
* @param istate Pointer to the 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(uintptr_t 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->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)) {
if (((access == PF_ACCESS_READ) && PTE_READABLE(pte)) ||
(access == PF_ACCESS_WRITE && PTE_WRITABLE(pte)) ||
(access == PF_ACCESS_EXEC && PTE_EXECUTABLE(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->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,
(uintptr_t) &memcpy_from_uspace_failover_address);
} else if (THREAD->in_copy_to_uspace) {
THREAD->in_copy_to_uspace = false;
istate_set_retaddr(istate,
(uintptr_t) &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
* scheduling. Sleeping here would lead to deadlock on wakeup. Another
* thing which is forbidden in this context is locking the address space.
*
* When this function is enetered, no spinlocks may be held.
*
* @param old Old address space or NULL.
* @param new New address space.
*/
void as_switch(as_t *old_as, as_t *new_as)
{
DEADLOCK_PROBE_INIT(p_asidlock);
preemption_disable();
retry:
(void) interrupts_disable();
if (!spinlock_trylock(&asidlock)) {
/*
* Avoid deadlock with TLB shootdown.
* We can enable interrupts here because
* preemption is disabled. We should not be
* holding any other lock.
*/
(void) interrupts_enable();
DEADLOCK_PROBE(p_asidlock, DEADLOCK_THRESHOLD);
goto retry;
}
preemption_enable();
/*
* First, take care of the old address space.
*/
if (old_as) {
ASSERT(old_as->cpu_refcount);
if((--old_as->cpu_refcount == 0) && (old_as != 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_as->asid != ASID_INVALID);
list_append(&old_as->inactive_as_with_asid_link,
&inactive_as_with_asid_head);
}
/*
* Perform architecture-specific tasks when the address space
* is being removed from the CPU.
*/
as_deinstall_arch(old_as);
}
/*
* Second, prepare the new address space.
*/
if ((new_as->cpu_refcount++ == 0) && (new_as != AS_KERNEL)) {
if (new_as->asid != ASID_INVALID)
list_remove(&new_as->inactive_as_with_asid_link);
else
new_as->asid = asid_get();
}
#ifdef AS_PAGE_TABLE
SET_PTL0_ADDRESS(new_as->genarch.page_table);
#endif
/*
* Perform architecture-specific steps.
* (e.g. write ASID to hardware register etc.)
*/
as_install_arch(new_as);
spinlock_unlock(&asidlock);
AS = new_as;
}
/** Write directly into a page, bypassing area flags.
*
* This allows a debugger to write into a page that is mapped read-only
* (such as the text segment). Naturally, this is only possible if the
* correspoinding area is not shared and anonymous.
*
* FIXME: doesn't take into account that it isn't a good idea to write
* into the frame if the area is shared or isn't anonymous
*/
static int debug_write_inside_page(uintptr_t va, void *data, size_t n)
{
uintptr_t page;
pte_t *pte;
as_area_t *area;
uintptr_t frame;
ipl_t ipl;
int rc;
page = ALIGN_DOWN(va, PAGE_SIZE);
ASSERT(ALIGN_DOWN(va + n - 1, PAGE_SIZE) == page);
restart:
mutex_lock(&AS->lock);
ipl = interrupts_disable();
area = find_area_and_lock(AS, page);
if (area->backend != &anon_backend || area->sh_info != NULL) {
mutex_unlock(&area->lock);
mutex_unlock(&AS->lock);
interrupts_restore(ipl);
rc = as_area_make_writeable(area->base);
if (rc != 0) return rc;
goto restart;
}
pte = page_mapping_find(AS, page);
if (! (pte && PTE_VALID(pte) && PTE_PRESENT(pte)) ) {
mutex_unlock(&area->lock);
mutex_unlock(&AS->lock);
interrupts_restore(ipl);
rc = as_page_fault(page, PF_ACCESS_WRITE, NULL);
if (rc == AS_PF_FAULT) return EINVAL;
goto restart;
}
frame = PTE_GET_FRAME(pte);
memcpy((void *)(PA2KA
(frame
) + (va
- page
)), data
, n
);
mutex_unlock(&area->lock);
mutex_unlock(&AS->lock);
interrupts_restore(ipl);
return EOK;
}
/** Write data bypassing area flags.
*
* See debug_write_inside_page().
*/
int as_debug_write(uintptr_t va, void *data, size_t n)
{
size_t now;
int rc;
while (n > 0) {
/* Number of bytes until the end of page */
now = ALIGN_DOWN(va, PAGE_SIZE) + PAGE_SIZE - va;
if (now > n) now = n;
rc = debug_write_inside_page(va, data, now);
if (rc != EOK) return rc;
va += now;
data += now;
n -= now;
}
return EOK;
}
/** Make sure area is private and anonymous.
*
* Not atomic atm.
* @param address Virtual address in AS.
*/
int as_area_make_writeable(uintptr_t address)
{
ipl_t ipl;
as_area_t *area;
uintptr_t base, page;
uintptr_t old_frame, frame;
size_t size;
int flags;
int page_flags;
pte_t *pte;
int rc;
uintptr_t *pagemap;
ipl = interrupts_disable();
mutex_lock(&AS->lock);
area = find_area_and_lock(AS, address);
if (!area) {
/*
* Could not find the address space area.
*/
mutex_unlock(&AS->lock);
interrupts_restore(ipl);
return ENOENT;
}
if (area->backend == &anon_backend && !area->sh_info) {
/* Nothing to do */
mutex_unlock(&area->lock);
mutex_unlock(&AS->lock);
interrupts_restore(ipl);
return EOK;
}
base = area->base;
size = area->pages * PAGE_SIZE;
flags = area->flags;
page_flags = as_area_get_flags(area);
pagemap
= malloc(area
->pages
* sizeof(uintptr_t), 0); page_table_lock(AS, false);
for (page = base; page < base + size; page += PAGE_SIZE) {
pte = page_mapping_find(AS, page);
if (!pte || !PTE_PRESENT(pte) || !PTE_READABLE(pte)) {
/* Fetch the missing page */
if (!area->backend || !area->backend->page_fault) {
page_table_unlock(AS, false);
mutex_unlock(&area->lock);
mutex_unlock(&AS->lock);
interrupts_restore(ipl);
return EINVAL;
}
if (area->backend->page_fault(area, page, PF_ACCESS_READ) != AS_PF_OK) {
page_table_unlock(AS, false);
mutex_unlock(&area->lock);
mutex_unlock(&AS->lock);
interrupts_restore(ipl);
return EINVAL;
}
}
ASSERT(PTE_VALID(pte));
old_frame = PTE_GET_FRAME(pte);
frame = (uintptr_t)frame_alloc(ONE_FRAME, 0);
memcpy((void *) PA2KA
(frame
), (void *)PA2KA
(old_frame
), FRAME_SIZE);
pagemap[(page - base) / PAGE_SIZE] = frame;
}
page_table_unlock(AS, false);
mutex_unlock(&area->lock);
mutex_unlock(&AS->lock);
interrupts_restore(ipl);
rc = as_area_destroy(AS, address);
if (rc < 0) {
return rc;
}
area = as_area_create(AS, flags, size, base, AS_AREA_ATTR_PARTIAL,
&anon_backend, NULL);
if (area == NULL) {
return rc;
}
mutex_lock(&AS->lock);
mutex_lock(&area->lock);
page_table_lock(AS, false);
for (page = base; page < base + size; page += PAGE_SIZE) {
frame = pagemap[(page - base) / PAGE_SIZE];
page_mapping_insert(AS, page, frame, page_flags);
if (!used_space_insert(area, page, 1))
panic("Could not insert used space.\n");
}
page_table_unlock(AS, false);
area->attributes &= ~AS_AREA_ATTR_PARTIAL;
mutex_unlock(&area->lock);
mutex_unlock(&AS->lock);
return EOK;
}
/** 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_CACHEABLE)
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 the 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);
}
/** Destroy page table.
*
* Destroy page table in architecture specific way.
*
* @param page_table Physical address of PTL0.
*/
void page_table_destroy(pte_t *page_table)
{
ASSERT(as_operations);
ASSERT(as_operations->page_table_destroy);
as_operations->page_table_destroy(page_table);
}
/** 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, uintptr_t va)
{
as_area_t *a;
btree_node_t *leaf, *lnode;
unsigned 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.
*/
lnode = btree_leaf_node_left_neighbour(&as->as_area_btree, leaf);
if (lnode) {
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, uintptr_t va, size_t size, as_area_t *avoid_area)
{
as_area_t *a;
btree_node_t *leaf, *node;
unsigned 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);
}
node = btree_leaf_node_right_neighbour(&as->as_area_btree, leaf);
if (node) {
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.
*
* @param base Arbitrary address insede the address space area.
*
* @return Size of the address space area in bytes or zero if it
* does not exist.
*/
size_t as_area_get_size(uintptr_t 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 Zero on failure and non-zero on success.
*/
int used_space_insert(as_area_t *a, uintptr_t page, count_t count)
{
btree_node_t *leaf, *node;
count_t pages;
unsigned 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;
}
if (!leaf->keys) {
btree_insert(&a->used_space, page, (void *) count, leaf);
return 1;
}
node = btree_leaf_node_left_neighbour(&a->used_space, leaf);
if (node) {
uintptr_t left_pg = node->key[node->keys - 1];
uintptr_t right_pg = leaf->key[0];
count_t left_cnt = (count_t) node->value[node->keys - 1];
count_t 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]) {
uintptr_t 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) {
uintptr_t left_pg = leaf->key[leaf->keys - 1];
uintptr_t right_pg = node->key[0];
count_t left_cnt = (count_t) leaf->value[leaf->keys - 1];
count_t 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]) {
uintptr_t 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]) {
uintptr_t left_pg = leaf->key[i - 1];
uintptr_t right_pg = leaf->key[i];
count_t left_cnt = (count_t) leaf->value[i - 1];
count_t 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 %" PRIc " 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 Zero on failure and non-zero on success.
*/
int used_space_remove(as_area_t *a, uintptr_t page, count_t count)
{
btree_node_t *leaf, *node;
count_t pages;
unsigned 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]) {
uintptr_t 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]) {
uintptr_t 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]) {
uintptr_t 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 %" PRIc " 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;
link_t *cur;
/*
* Now walk carefully the pagemap B+tree and free/remove
* reference from all frames found there.
*/
for (cur = sh_info->pagemap.leaf_head.next;
cur != &sh_info->pagemap.leaf_head; cur = cur->next) {
btree_node_t *node;
unsigned int i;
node = list_get_instance(cur, btree_node_t, leaf_link);
for (i = 0; i < node->keys; i++)
frame_free((uintptr_t) node->value[i]);
}
}
mutex_unlock(&sh_info->lock);
if (dealloc) {
btree_destroy(&sh_info->pagemap);
}
}
/*
* Address space related syscalls.
*/
/** Wrapper for as_area_create(). */
unative_t sys_as_area_create(uintptr_t address, size_t size, int flags)
{
if (as_area_create(AS, flags | AS_AREA_CACHEABLE, size, address,
AS_AREA_ATTR_NONE, &anon_backend, NULL))
return (unative_t) address;
else
return (unative_t) -1;
}
/** Wrapper for as_area_resize(). */
unative_t sys_as_area_resize(uintptr_t address, size_t size, int flags)
{
return (unative_t) as_area_resize(AS, address, size, 0);
}
/** Wrapper for as_area_change_flags(). */
unative_t sys_as_area_change_flags(uintptr_t address, int flags)
{
return (unative_t) as_area_change_flags(AS, flags, address);
}
/** Wrapper for as_area_destroy(). */
unative_t sys_as_area_destroy(uintptr_t address)
{
return (unative_t) as_area_destroy(AS, address);
}
/** Print out information about address space.
*
* @param as Address space.
*/
void as_print(as_t *as)
{
ipl_t ipl;
ipl = interrupts_disable();
mutex_lock(&as->lock);
/* print out info about address space areas */
link_t *cur;
for (cur = as->as_area_btree.leaf_head.next;
cur != &as->as_area_btree.leaf_head; cur = cur->next) {
btree_node_t *node;
node = list_get_instance(cur, btree_node_t, leaf_link);
unsigned int i;
for (i = 0; i < node->keys; i++) {
as_area_t *area = node->value[i];
mutex_lock(&area->lock);
printf("as_area: %p, base=%p, pages=%" PRIc
" (%p - %p)\n", area, area->base, area->pages,
area->base, area->base + FRAMES2SIZE(area->pages));
mutex_unlock(&area->lock);
}
}
mutex_unlock(&as->lock);
interrupts_restore(ipl);
}
/** @}
*/