WebSVN – HelenOS-historic – Diff – /kernel/trunk/generic/src/mm/as.c


/*
 * 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;
 
/** This lock protects inactive_as_with_asid_head list. It must be acquired before as_t mutex. */
SPINLOCK_INITIALIZE(inactive_as_with_asid_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->cpu_refcount = 0;
    as->page_table = page_table_create(flags);
 
    return as;
}
 
/** Free Adress space */
void as_free(as_t *as)
{
    ASSERT(as->cpu_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;
}
 
/** Share address space area with another or the same address space.
 *
 * Address space area of anonymous memory 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 and the original mapping is duplicated
 * in its pagemap B+tree. The new address space are simply gets the
 * sh_info of the source area.
 *
 * @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_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 an attempt
 *     to share non-anonymous address space area is detected.
 */
int as_area_share(as_t *src_as, __address src_base, size_t acc_size,
          __address 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;
    link_t *cur;
 
    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 != &anon_backend) {
        /*
         * As of now, only anonymous address space areas can be shared.
         */
        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;
   
    if (src_size != acc_size) {
        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);
        sh_info->refcount = 2;
        btree_create(&sh_info->pagemap);
        src_area->sh_info = sh_info;
    } else {
        mutex_lock(&sh_info->lock);
        sh_info->refcount++;
        mutex_unlock(&sh_info->lock);
    }
 
    /*
     * Copy used portions of the area to sh_info's page map.
     */
    mutex_lock(&sh_info->lock);
    for (cur = src_area->used_space.leaf_head.next; cur != &src_area->used_space.leaf_head; cur = cur->next) {
        btree_node_t *node;
        int i;
       
        node = list_get_instance(cur, btree_node_t, leaf_link);
        for (i = 0; i < node->keys; i++) {
            __address base = node->key[i];
            count_t count = (count_t) node->value[i];
            int j;
           
            for (j = 0; j < count; j++) {
                pte_t *pte;
           
                page_table_lock(src_as, false);
                pte = page_mapping_find(src_as, base + j*PAGE_SIZE);
                ASSERT(pte && PTE_VALID(pte) && PTE_PRESENT(pte));
                btree_insert(&sh_info->pagemap, (base + j*PAGE_SIZE) - src_area->base,
                    (void *) PTE_GET_FRAME(pte), NULL);
                page_table_unlock(src_as, false);
            }
               
        }
    }
    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(AS, src_flags & dst_flags_mask, src_size, dst_base,
                  AS_AREA_ATTR_PARTIAL, &anon_backend, NULL);
    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_area->lock);
    dst_area->attributes &= ~AS_AREA_ATTR_PARTIAL;
    dst_area->sh_info = sh_info;
    mutex_unlock(&dst_area->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);
}
 
/** 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;
}
 
/** 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)) {
            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->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
 * 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(&inactive_as_with_asid_lock);
 
    /*
     * First, take care of the old address space.
     */
    if (old) {
        mutex_lock_active(&old->lock);
        ASSERT(old->cpu_refcount);
        if((--old->cpu_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->cpu_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(&inactive_as_with_asid_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 (!as_area_check_access(area, access))
        return AS_PF_FAULT;
 
    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) - area->base, &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) - area->base, (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);
}
 

Rev 1417	Rev 1423
1	/*	1	/*
2	* Copyright (C) 2001-2006 Jakub Jermar	2	* Copyright (C) 2001-2006 Jakub Jermar
3	* All rights reserved.	3	* All rights reserved.
4	*	4	*
5	* Redistribution and use in source and binary forms, with or without	5	* Redistribution and use in source and binary forms, with or without
6	* modification, are permitted provided that the following conditions	6	* modification, are permitted provided that the following conditions
7	* are met:	7	* are met:
8	*	8	*
9	* - Redistributions of source code must retain the above copyright	9	* - Redistributions of source code must retain the above copyright
10	* notice, this list of conditions and the following disclaimer.	10	* notice, this list of conditions and the following disclaimer.
11	* - Redistributions in binary form must reproduce the above copyright	11	* - Redistributions in binary form must reproduce the above copyright
12	* notice, this list of conditions and the following disclaimer in the	12	* notice, this list of conditions and the following disclaimer in the
13	* documentation and/or other materials provided with the distribution.	13	* documentation and/or other materials provided with the distribution.
14	* - The name of the author may not be used to endorse or promote products	14	* - The name of the author may not be used to endorse or promote products
15	* derived from this software without specific prior written permission.	15	* derived from this software without specific prior written permission.
16	*	16	*
17	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR	17	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
18	* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES	18	* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
19	* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.	19	* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
20	* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,	20	* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
21	* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT	21	* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
22	* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,	22	* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23	* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY	23	* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24	* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT	24	* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF	25	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26	* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.	26	* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27	*/	27	*/
28		28
29	/**	29	/**
30	* @file as.c	30	* @file as.c
31	* @brief Address space related functions.	31	* @brief Address space related functions.
32	*	32	*
33	* This file contains address space manipulation functions.	33	* This file contains address space manipulation functions.
34	* Roughly speaking, this is a higher-level client of	34	* Roughly speaking, this is a higher-level client of
35	* Virtual Address Translation (VAT) subsystem.	35	* Virtual Address Translation (VAT) subsystem.
36	*	36	*
37	* Functionality provided by this file allows one to	37	* Functionality provided by this file allows one to
38	* create address space and create, resize and share	38	* create address space and create, resize and share
39	* address space areas.	39	* address space areas.
40	*	40	*
41	* @see page.c	41	* @see page.c
42	*	42	*
43	*/	43	*/
44		44
45	#include <mm/as.h>	45	#include <mm/as.h>
46	#include <arch/mm/as.h>	46	#include <arch/mm/as.h>
47	#include <mm/page.h>	47	#include <mm/page.h>
48	#include <mm/frame.h>	48	#include <mm/frame.h>
49	#include <mm/slab.h>	49	#include <mm/slab.h>
50	#include <mm/tlb.h>	50	#include <mm/tlb.h>
51	#include <arch/mm/page.h>	51	#include <arch/mm/page.h>
52	#include <genarch/mm/page_pt.h>	52	#include <genarch/mm/page_pt.h>
53	#include <genarch/mm/page_ht.h>	53	#include <genarch/mm/page_ht.h>
54	#include <mm/asid.h>	54	#include <mm/asid.h>
55	#include <arch/mm/asid.h>	55	#include <arch/mm/asid.h>
56	#include <synch/spinlock.h>	56	#include <synch/spinlock.h>
57	#include <synch/mutex.h>	57	#include <synch/mutex.h>
58	#include <adt/list.h>	58	#include <adt/list.h>
59	#include <adt/btree.h>	59	#include <adt/btree.h>
60	#include <proc/task.h>	60	#include <proc/task.h>
61	#include <proc/thread.h>	61	#include <proc/thread.h>
62	#include <arch/asm.h>	62	#include <arch/asm.h>
63	#include <panic.h>	63	#include <panic.h>
64	#include <debug.h>	64	#include <debug.h>
65	#include <print.h>	65	#include <print.h>
66	#include <memstr.h>	66	#include <memstr.h>
67	#include <macros.h>	67	#include <macros.h>
68	#include <arch.h>	68	#include <arch.h>
69	#include <errno.h>	69	#include <errno.h>
70	#include <config.h>	70	#include <config.h>
71	#include <align.h>	71	#include <align.h>
72	#include <arch/types.h>	72	#include <arch/types.h>
73	#include <typedefs.h>	73	#include <typedefs.h>
74	#include <syscall/copy.h>	74	#include <syscall/copy.h>
75	#include <arch/interrupt.h>	75	#include <arch/interrupt.h>
76		76
77	/** This structure contains information associated with the shared address space area. */	77	/** This structure contains information associated with the shared address space area. */
78	struct share_info {	78	struct share_info {
79	mutex_t lock; /*< This lock must be acquired only when the as_area lock is held. /	79	mutex_t lock; /*< This lock must be acquired only when the as_area lock is held. /
80	count_t refcount; /*< This structure can be deallocated if refcount drops to 0. /	80	count_t refcount; /*< This structure can be deallocated if refcount drops to 0. /
81	btree_t pagemap; /*< B+tree containing complete map of anonymous pages of the shared area. /	81	btree_t pagemap; /*< B+tree containing complete map of anonymous pages of the shared area. /
82	};	82	};
83		83
84	as_operations_t *as_operations = NULL;	84	as_operations_t *as_operations = NULL;
85		85
86	/** This lock protects inactive_as_with_asid_head list. It must be acquired before as_t mutex. */	86	/** This lock protects inactive_as_with_asid_head list. It must be acquired before as_t mutex. */
87	SPINLOCK_INITIALIZE(inactive_as_with_asid_lock);	87	SPINLOCK_INITIALIZE(inactive_as_with_asid_lock);
88		88
89	/**	89	/**
90	* This list contains address spaces that are not active on any	90	* This list contains address spaces that are not active on any
91	* processor and that have valid ASID.	91	* processor and that have valid ASID.
92	*/	92	*/
93	LIST_INITIALIZE(inactive_as_with_asid_head);	93	LIST_INITIALIZE(inactive_as_with_asid_head);
94		94
95	/** Kernel address space. */	95	/** Kernel address space. */
96	as_t *AS_KERNEL = NULL;	96	as_t *AS_KERNEL = NULL;
97		97
98	static int area_flags_to_page_flags(int aflags);	98	static int area_flags_to_page_flags(int aflags);
99	static as_area_t find_area_and_lock(as_t as, __address va);	99	static as_area_t find_area_and_lock(as_t as, __address va);
100	static bool check_area_conflicts(as_t as, __address va, size_t size, as_area_t avoid_area);	100	static bool check_area_conflicts(as_t as, __address va, size_t size, as_area_t avoid_area);
101	static void sh_info_remove_reference(share_info_t *sh_info);	101	static void sh_info_remove_reference(share_info_t *sh_info);
102		102
103	/** Initialize address space subsystem. */	103	/** Initialize address space subsystem. */
104	void as_init(void)	104	void as_init(void)
105	{	105	{
106	as_arch_init();	106	as_arch_init();
107	AS_KERNEL = as_create(FLAG_AS_KERNEL);	107	AS_KERNEL = as_create(FLAG_AS_KERNEL);
108	if (!AS_KERNEL)	108	if (!AS_KERNEL)
109	panic("can't create kernel address space\n");	109	panic("can't create kernel address space\n");
110		110
111	}	111	}
112		112
113	/** Create address space.	113	/** Create address space.
114	*	114	*
115	* @param flags Flags that influence way in wich the address space is created.	115	* @param flags Flags that influence way in wich the address space is created.
116	*/	116	*/
117	as_t *as_create(int flags)	117	as_t *as_create(int flags)
118	{	118	{
119	as_t *as;	119	as_t *as;
120		120
121	as = (as_t *) malloc(sizeof(as_t), 0);	121	as = (as_t *) malloc(sizeof(as_t), 0);
122	link_initialize(&as->inactive_as_with_asid_link);	122	link_initialize(&as->inactive_as_with_asid_link);
123	mutex_initialize(&as->lock);	123	mutex_initialize(&as->lock);
124	btree_create(&as->as_area_btree);	124	btree_create(&as->as_area_btree);
125		125
126	if (flags & FLAG_AS_KERNEL)	126	if (flags & FLAG_AS_KERNEL)
127	as->asid = ASID_KERNEL;	127	as->asid = ASID_KERNEL;
128	else	128	else
129	as->asid = ASID_INVALID;	129	as->asid = ASID_INVALID;
130		130
131	as->cpu_refcount = 0;	131	as->cpu_refcount = 0;
132	as->page_table = page_table_create(flags);	132	as->page_table = page_table_create(flags);
133		133
134	return as;	134	return as;
135	}	135	}
136		136
137	/** Free Adress space */	137	/** Free Adress space */
138	void as_free(as_t *as)	138	void as_free(as_t *as)
139	{	139	{
140	ASSERT(as->cpu_refcount == 0);	140	ASSERT(as->cpu_refcount == 0);
141		141
142	/* TODO: free as_areas and other resources held by as */	142	/* TODO: free as_areas and other resources held by as */
143	/* TODO: free page table */	143	/* TODO: free page table */
144	free(as);	144	free(as);
145	}	145	}
146		146
147	/** Create address space area of common attributes.	147	/** Create address space area of common attributes.
148	*	148	*
149	* The created address space area is added to the target address space.	149	* The created address space area is added to the target address space.
150	*	150	*
151	* @param as Target address space.	151	* @param as Target address space.
152	* @param flags Flags of the area memory.	152	* @param flags Flags of the area memory.
153	* @param size Size of area.	153	* @param size Size of area.
154	* @param base Base address of area.	154	* @param base Base address of area.
155	* @param attrs Attributes of the area.	155	* @param attrs Attributes of the area.
156	* @param backend Address space area backend. NULL if no backend is used.	156	* @param backend Address space area backend. NULL if no backend is used.
157	* @param backend_data NULL or a pointer to an array holding two void *.	157	* @param backend_data NULL or a pointer to an array holding two void *.
158	*	158	*
159	* @return Address space area on success or NULL on failure.	159	* @return Address space area on success or NULL on failure.
160	*/	160	*/
161	as_area_t as_area_create(as_t as, int flags, size_t size, __address base, int attrs,	161	as_area_t as_area_create(as_t as, int flags, size_t size, __address base, int attrs,
162	mem_backend_t backend, void *backend_data)	162	mem_backend_t backend, void *backend_data)
163	{	163	{
164	ipl_t ipl;	164	ipl_t ipl;
165	as_area_t *a;	165	as_area_t *a;
166		166
167	if (base % PAGE_SIZE)	167	if (base % PAGE_SIZE)
168	return NULL;	168	return NULL;
169		169
170	if (!size)	170	if (!size)
171	return NULL;	171	return NULL;
172		172
173	/* Writeable executable areas are not supported. */	173	/* Writeable executable areas are not supported. */
174	if ((flags & AS_AREA_EXEC) && (flags & AS_AREA_WRITE))	174	if ((flags & AS_AREA_EXEC) && (flags & AS_AREA_WRITE))
175	return NULL;	175	return NULL;
176		176
177	ipl = interrupts_disable();	177	ipl = interrupts_disable();
178	mutex_lock(&as->lock);	178	mutex_lock(&as->lock);
179		179
180	if (!check_area_conflicts(as, base, size, NULL)) {	180	if (!check_area_conflicts(as, base, size, NULL)) {
181	mutex_unlock(&as->lock);	181	mutex_unlock(&as->lock);
182	interrupts_restore(ipl);	182	interrupts_restore(ipl);
183	return NULL;	183	return NULL;
184	}	184	}
185		185
186	a = (as_area_t *) malloc(sizeof(as_area_t), 0);	186	a = (as_area_t *) malloc(sizeof(as_area_t), 0);
187		187
188	mutex_initialize(&a->lock);	188	mutex_initialize(&a->lock);
189		189
190	a->flags = flags;	190	a->flags = flags;
191	a->attributes = attrs;	191	a->attributes = attrs;
192	a->pages = SIZE2FRAMES(size);	192	a->pages = SIZE2FRAMES(size);
193	a->base = base;	193	a->base = base;
194	a->sh_info = NULL;	194	a->sh_info = NULL;
195	a->backend = backend;	195	a->backend = backend;
196	if (backend_data) {	196	if (backend_data) {
197	a->backend_data[0] = backend_data[0];	197	a->backend_data[0] = backend_data[0];
198	a->backend_data[1] = backend_data[1];	198	a->backend_data[1] = backend_data[1];
199	}	199	}
200	btree_create(&a->used_space);	200	btree_create(&a->used_space);
201		201
202	btree_insert(&as->as_area_btree, base, (void *) a, NULL);	202	btree_insert(&as->as_area_btree, base, (void *) a, NULL);
203		203
204	mutex_unlock(&as->lock);	204	mutex_unlock(&as->lock);
205	interrupts_restore(ipl);	205	interrupts_restore(ipl);
206		206
207	return a;	207	return a;
208	}	208	}
209		209
210	/** Find address space area and change it.	210	/** Find address space area and change it.
211	*	211	*
212	* @param as Address space.	212	* @param as Address space.
213	* @param address Virtual address belonging to the area to be changed. Must be page-aligned.	213	* @param address Virtual address belonging to the area to be changed. Must be page-aligned.
214	* @param size New size of the virtual memory block starting at address.	214	* @param size New size of the virtual memory block starting at address.
215	* @param flags Flags influencing the remap operation. Currently unused.	215	* @param flags Flags influencing the remap operation. Currently unused.
216	*	216	*
217	* @return Zero on success or a value from @ref errno.h otherwise.	217	* @return Zero on success or a value from @ref errno.h otherwise.
218	*/	218	*/
219	int as_area_resize(as_t *as, __address address, size_t size, int flags)	219	int as_area_resize(as_t *as, __address address, size_t size, int flags)
220	{	220	{
221	as_area_t *area;	221	as_area_t *area;
222	ipl_t ipl;	222	ipl_t ipl;
223	size_t pages;	223	size_t pages;
224		224
225	ipl = interrupts_disable();	225	ipl = interrupts_disable();
226	mutex_lock(&as->lock);	226	mutex_lock(&as->lock);
227		227
228	/*	228	/*
229	* Locate the area.	229	* Locate the area.
230	*/	230	*/
231	area = find_area_and_lock(as, address);	231	area = find_area_and_lock(as, address);
232	if (!area) {	232	if (!area) {
233	mutex_unlock(&as->lock);	233	mutex_unlock(&as->lock);
234	interrupts_restore(ipl);	234	interrupts_restore(ipl);
235	return ENOENT;	235	return ENOENT;
236	}	236	}
237		237
238	if (area->flags & AS_AREA_DEVICE) {	238	if (area->flags & AS_AREA_DEVICE) {
239	/*	239	/*
240	* Remapping of address space areas associated	240	* Remapping of address space areas associated
241	* with memory mapped devices is not supported.	241	* with memory mapped devices is not supported.
242	*/	242	*/
243	mutex_unlock(&area->lock);	243	mutex_unlock(&area->lock);
244	mutex_unlock(&as->lock);	244	mutex_unlock(&as->lock);
245	interrupts_restore(ipl);	245	interrupts_restore(ipl);
246	return ENOTSUP;	246	return ENOTSUP;
247	}	247	}
248	if (area->sh_info) {	248	if (area->sh_info) {
249	/*	249	/*
250	* Remapping of shared address space areas	250	* Remapping of shared address space areas
251	* is not supported.	251	* is not supported.
252	*/	252	*/
253	mutex_unlock(&area->lock);	253	mutex_unlock(&area->lock);
254	mutex_unlock(&as->lock);	254	mutex_unlock(&as->lock);
255	interrupts_restore(ipl);	255	interrupts_restore(ipl);
256	return ENOTSUP;	256	return ENOTSUP;
257	}	257	}
258		258
259	pages = SIZE2FRAMES((address - area->base) + size);	259	pages = SIZE2FRAMES((address - area->base) + size);
260	if (!pages) {	260	if (!pages) {
261	/*	261	/*
262	* Zero size address space areas are not allowed.	262	* Zero size address space areas are not allowed.
263	*/	263	*/
264	mutex_unlock(&area->lock);	264	mutex_unlock(&area->lock);
265	mutex_unlock(&as->lock);	265	mutex_unlock(&as->lock);
266	interrupts_restore(ipl);	266	interrupts_restore(ipl);
267	return EPERM;	267	return EPERM;
268	}	268	}
269		269
270	if (pages < area->pages) {	270	if (pages < area->pages) {
271	bool cond;	271	bool cond;
272	__address start_free = area->base + pages*PAGE_SIZE;	272	__address start_free = area->base + pages*PAGE_SIZE;
273		273
274	/*	274	/*
275	* Shrinking the area.	275	* Shrinking the area.
276	* No need to check for overlaps.	276	* No need to check for overlaps.
277	*/	277	*/
278		278
279	/*	279	/*
280	* Remove frames belonging to used space starting from	280	* Remove frames belonging to used space starting from
281	* the highest addresses downwards until an overlap with	281	* the highest addresses downwards until an overlap with
282	* the resized address space area is found. Note that this	282	* the resized address space area is found. Note that this
283	* is also the right way to remove part of the used_space	283	* is also the right way to remove part of the used_space
284	* B+tree leaf list.	284	* B+tree leaf list.
285	*/	285	*/
286	for (cond = true; cond;) {	286	for (cond = true; cond;) {
287	btree_node_t *node;	287	btree_node_t *node;
288		288
289	ASSERT(!list_empty(&area->used_space.leaf_head));	289	ASSERT(!list_empty(&area->used_space.leaf_head));
290	node = list_get_instance(area->used_space.leaf_head.prev, btree_node_t, leaf_link);	290	node = list_get_instance(area->used_space.leaf_head.prev, btree_node_t, leaf_link);
291	if ((cond = (bool) node->keys)) {	291	if ((cond = (bool) node->keys)) {
292	__address b = node->key[node->keys - 1];	292	__address b = node->key[node->keys - 1];
293	count_t c = (count_t) node->value[node->keys - 1];	293	count_t c = (count_t) node->value[node->keys - 1];
294	int i = 0;	294	int i = 0;
295		295
296	if (overlaps(b, cPAGE_SIZE, area->base, pagesPAGE_SIZE)) {	296	if (overlaps(b, cPAGE_SIZE, area->base, pagesPAGE_SIZE)) {
297		297
298	if (b + c*PAGE_SIZE <= start_free) {	298	if (b + c*PAGE_SIZE <= start_free) {
299	/*	299	/*
300	* The whole interval fits completely	300	* The whole interval fits completely
301	* in the resized address space area.	301	* in the resized address space area.
302	*/	302	*/
303	break;	303	break;
304	}	304	}
305		305
306	/*	306	/*
307	* Part of the interval corresponding to b and c	307	* Part of the interval corresponding to b and c
308	* overlaps with the resized address space area.	308	* overlaps with the resized address space area.
309	*/	309	*/
310		310
311	cond = false; /* we are almost done */	311	cond = false; /* we are almost done */
312	i = (start_free - b) >> PAGE_WIDTH;	312	i = (start_free - b) >> PAGE_WIDTH;
313	if (!used_space_remove(area, start_free, c - i))	313	if (!used_space_remove(area, start_free, c - i))
314	panic("Could not remove used space.");	314	panic("Could not remove used space.");
315	} else {	315	} else {
316	/*	316	/*
317	* The interval of used space can be completely removed.	317	* The interval of used space can be completely removed.
318	*/	318	*/
319	if (!used_space_remove(area, b, c))	319	if (!used_space_remove(area, b, c))
320	panic("Could not remove used space.\n");	320	panic("Could not remove used space.\n");
321	}	321	}
322		322
323	for (; i < c; i++) {	323	for (; i < c; i++) {
324	pte_t *pte;	324	pte_t *pte;
325		325
326	page_table_lock(as, false);	326	page_table_lock(as, false);
327	pte = page_mapping_find(as, b + i*PAGE_SIZE);	327	pte = page_mapping_find(as, b + i*PAGE_SIZE);
328	ASSERT(pte && PTE_VALID(pte) && PTE_PRESENT(pte));	328	ASSERT(pte && PTE_VALID(pte) && PTE_PRESENT(pte));
329	if (area->backend && area->backend->backend_frame_free) {	329	if (area->backend && area->backend->backend_frame_free) {
330	area->backend->backend_frame_free(area,	330	area->backend->backend_frame_free(area,
331	b + i*PAGE_SIZE, PTE_GET_FRAME(pte));	331	b + i*PAGE_SIZE, PTE_GET_FRAME(pte));
332	}	332	}
333	page_mapping_remove(as, b + i*PAGE_SIZE);	333	page_mapping_remove(as, b + i*PAGE_SIZE);
334	page_table_unlock(as, false);	334	page_table_unlock(as, false);
335	}	335	}
336	}	336	}
337	}	337	}
338	/*	338	/*
339	* Invalidate TLB's.	339	* Invalidate TLB's.
340	*/	340	*/
341	tlb_shootdown_start(TLB_INVL_PAGES, AS->asid, area->base + pages*PAGE_SIZE, area->pages - pages);	341	tlb_shootdown_start(TLB_INVL_PAGES, AS->asid, area->base + pages*PAGE_SIZE, area->pages - pages);
342	tlb_invalidate_pages(AS->asid, area->base + pages*PAGE_SIZE, area->pages - pages);	342	tlb_invalidate_pages(AS->asid, area->base + pages*PAGE_SIZE, area->pages - pages);
343	tlb_shootdown_finalize();	343	tlb_shootdown_finalize();
344	} else {	344	} else {
345	/*	345	/*
346	* Growing the area.	346	* Growing the area.
347	* Check for overlaps with other address space areas.	347	* Check for overlaps with other address space areas.
348	*/	348	*/
349	if (!check_area_conflicts(as, address, pages * PAGE_SIZE, area)) {	349	if (!check_area_conflicts(as, address, pages * PAGE_SIZE, area)) {
350	mutex_unlock(&area->lock);	350	mutex_unlock(&area->lock);
351	mutex_unlock(&as->lock);	351	mutex_unlock(&as->lock);
352	interrupts_restore(ipl);	352	interrupts_restore(ipl);
353	return EADDRNOTAVAIL;	353	return EADDRNOTAVAIL;
354	}	354	}
355	}	355	}
356		356
357	area->pages = pages;	357	area->pages = pages;
358		358
359	mutex_unlock(&area->lock);	359	mutex_unlock(&area->lock);
360	mutex_unlock(&as->lock);	360	mutex_unlock(&as->lock);
361	interrupts_restore(ipl);	361	interrupts_restore(ipl);
362		362
363	return 0;	363	return 0;
364	}	364	}
365		365
366	/** Destroy address space area.	366	/** Destroy address space area.
367	*	367	*
368	* @param as Address space.	368	* @param as Address space.
369	* @param address Address withing the area to be deleted.	369	* @param address Address withing the area to be deleted.
370	*	370	*
371	* @return Zero on success or a value from @ref errno.h on failure.	371	* @return Zero on success or a value from @ref errno.h on failure.
372	*/	372	*/
373	int as_area_destroy(as_t *as, __address address)	373	int as_area_destroy(as_t *as, __address address)
374	{	374	{
375	as_area_t *area;	375	as_area_t *area;
376	__address base;	376	__address base;
377	ipl_t ipl;	377	ipl_t ipl;
378	bool cond;	378	bool cond;
379		379
380	ipl = interrupts_disable();	380	ipl = interrupts_disable();
381	mutex_lock(&as->lock);	381	mutex_lock(&as->lock);
382		382
383	area = find_area_and_lock(as, address);	383	area = find_area_and_lock(as, address);
384	if (!area) {	384	if (!area) {
385	mutex_unlock(&as->lock);	385	mutex_unlock(&as->lock);
386	interrupts_restore(ipl);	386	interrupts_restore(ipl);
387	return ENOENT;	387	return ENOENT;
388	}	388	}
389		389
390	base = area->base;	390	base = area->base;
391		391
392	/*	392	/*
393	* Visit only the pages mapped by used_space B+tree.	393	* Visit only the pages mapped by used_space B+tree.
394	* Note that we must be very careful when walking the tree	394	* Note that we must be very careful when walking the tree
395	* leaf list and removing used space as the leaf list changes	395	* leaf list and removing used space as the leaf list changes
396	* unpredictibly after each remove. The solution is to actually	396	* unpredictibly after each remove. The solution is to actually
397	* not walk the tree at all, but to remove items from the head	397	* not walk the tree at all, but to remove items from the head
398	* of the leaf list until there are some keys left.	398	* of the leaf list until there are some keys left.
399	*/	399	*/
400	for (cond = true; cond;) {	400	for (cond = true; cond;) {
401	btree_node_t *node;	401	btree_node_t *node;
402		402
403	ASSERT(!list_empty(&area->used_space.leaf_head));	403	ASSERT(!list_empty(&area->used_space.leaf_head));
404	node = list_get_instance(area->used_space.leaf_head.next, btree_node_t, leaf_link);	404	node = list_get_instance(area->used_space.leaf_head.next, btree_node_t, leaf_link);
405	if ((cond = (bool) node->keys)) {	405	if ((cond = (bool) node->keys)) {
406	__address b = node->key[0];	406	__address b = node->key[0];
407	count_t i;	407	count_t i;
408	pte_t *pte;	408	pte_t *pte;
409		409
410	for (i = 0; i < (count_t) node->value[0]; i++) {	410	for (i = 0; i < (count_t) node->value[0]; i++) {
411	page_table_lock(as, false);	411	page_table_lock(as, false);
412	pte = page_mapping_find(as, b + i*PAGE_SIZE);	412	pte = page_mapping_find(as, b + i*PAGE_SIZE);
413	ASSERT(pte && PTE_VALID(pte) && PTE_PRESENT(pte));	413	ASSERT(pte && PTE_VALID(pte) && PTE_PRESENT(pte));
414	if (area->backend && area->backend->backend_frame_free) {	414	if (area->backend && area->backend->backend_frame_free) {
415	area->backend->backend_frame_free(area,	415	area->backend->backend_frame_free(area,
416	b + i*PAGE_SIZE, PTE_GET_FRAME(pte));	416	b + i*PAGE_SIZE, PTE_GET_FRAME(pte));
417	}	417	}
418	page_mapping_remove(as, b + i*PAGE_SIZE);	418	page_mapping_remove(as, b + i*PAGE_SIZE);
419	page_table_unlock(as, false);	419	page_table_unlock(as, false);
420	}	420	}
421	if (!used_space_remove(area, b, i))	421	if (!used_space_remove(area, b, i))
422	panic("Could not remove used space.\n");	422	panic("Could not remove used space.\n");
423	}	423	}
424	}	424	}
425	btree_destroy(&area->used_space);	425	btree_destroy(&area->used_space);
426		426
427	/*	427	/*
428	* Invalidate TLB's.	428	* Invalidate TLB's.
429	*/	429	*/
430	tlb_shootdown_start(TLB_INVL_PAGES, AS->asid, area->base, area->pages);	430	tlb_shootdown_start(TLB_INVL_PAGES, AS->asid, area->base, area->pages);
431	tlb_invalidate_pages(AS->asid, area->base, area->pages);	431	tlb_invalidate_pages(AS->asid, area->base, area->pages);
432	tlb_shootdown_finalize();	432	tlb_shootdown_finalize();
433		433
434	area->attributes \|= AS_AREA_ATTR_PARTIAL;	434	area->attributes \|= AS_AREA_ATTR_PARTIAL;
435		435
436	if (area->sh_info)	436	if (area->sh_info)
437	sh_info_remove_reference(area->sh_info);	437	sh_info_remove_reference(area->sh_info);
438		438
439	mutex_unlock(&area->lock);	439	mutex_unlock(&area->lock);
440		440
441	/*	441	/*
442	* Remove the empty area from address space.	442	* Remove the empty area from address space.
443	*/	443	*/
444	btree_remove(&AS->as_area_btree, base, NULL);	444	btree_remove(&AS->as_area_btree, base, NULL);
445		445
446	free(area);	446	free(area);
447		447
448	mutex_unlock(&AS->lock);	448	mutex_unlock(&AS->lock);
449	interrupts_restore(ipl);	449	interrupts_restore(ipl);
450	return 0;	450	return 0;
451	}	451	}
452		452
453	/** Share address space area with another or the same address space.	453	/** Share address space area with another or the same address space.
454	*	454	*
455	* Address space area of anonymous memory is shared with a new address	455	* Address space area of anonymous memory is shared with a new address
456	* space area. If the source address space area has not been shared so	456	* space area. If the source address space area has not been shared so
457	* far, a new sh_info is created and the original mapping is duplicated	457	* far, a new sh_info is created and the original mapping is duplicated
458	* in its pagemap B+tree. The new address space are simply gets the	458	* in its pagemap B+tree. The new address space are simply gets the
459	* sh_info of the source area.	459	* sh_info of the source area.
460	*	460	*
461	* @param src_as Pointer to source address space.	461	* @param src_as Pointer to source address space.
462	* @param src_base Base address of the source address space area.	462	* @param src_base Base address of the source address space area.
463	* @param acc_size Expected size of the source area.	463	* @param acc_size Expected size of the source area.
464	* @param dst_base Target base address.	464	* @param dst_base Target base address.
465	* @param dst_flags_mask Destination address space area flags mask.	465	* @param dst_flags_mask Destination address space area flags mask.
466	*	466	*
467	* @return Zero on success or ENOENT if there is no such task or	467	* @return Zero on success or ENOENT if there is no such task or
468	* if there is no such address space area,	468	* if there is no such address space area,
469	* EPERM if there was a problem in accepting the area or	469	* EPERM if there was a problem in accepting the area or
470	* ENOMEM if there was a problem in allocating destination	470	* ENOMEM if there was a problem in allocating destination
471	* address space area. ENOTSUP is returned if an attempt	471	* address space area. ENOTSUP is returned if an attempt
472	* to share non-anonymous address space area is detected.	472	* to share non-anonymous address space area is detected.
473	*/	473	*/
474	int as_area_share(as_t *src_as, __address src_base, size_t acc_size,	474	int as_area_share(as_t *src_as, __address src_base, size_t acc_size,
475	__address dst_base, int dst_flags_mask)	475	__address dst_base, int dst_flags_mask)
476	{	476	{
477	ipl_t ipl;	477	ipl_t ipl;
478	int src_flags;	478	int src_flags;
479	size_t src_size;	479	size_t src_size;
480	as_area_t src_area, dst_area;	480	as_area_t src_area, dst_area;
481	share_info_t *sh_info;	481	share_info_t *sh_info;
482	link_t *cur;	482	link_t *cur;
483		483
484	ipl = interrupts_disable();	484	ipl = interrupts_disable();
485	mutex_lock(&src_as->lock);	485	mutex_lock(&src_as->lock);
486	src_area = find_area_and_lock(src_as, src_base);	486	src_area = find_area_and_lock(src_as, src_base);
487	if (!src_area) {	487	if (!src_area) {
488	/*	488	/*
489	* Could not find the source address space area.	489	* Could not find the source address space area.
490	*/	490	*/
491	mutex_unlock(&src_as->lock);	491	mutex_unlock(&src_as->lock);
492	interrupts_restore(ipl);	492	interrupts_restore(ipl);
493	return ENOENT;	493	return ENOENT;
494	}	494	}
495		495
496	if (!src_area->backend \|\| src_area->backend != &anon_backend) {	496	if (!src_area->backend \|\| src_area->backend != &anon_backend) {
497	/*	497	/*
498	* As of now, only anonymous address space areas can be shared.	498	* As of now, only anonymous address space areas can be shared.
499	*/	499	*/
500	mutex_unlock(&src_area->lock);	500	mutex_unlock(&src_area->lock);

Subversion Repositories HelenOS-historic

(root)/kernel/trunk/generic/src/mm/as.c – Rev 1417 → 1423