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>
 as_operations_t *as_operations = NULL;
 /** Address space lock. It protects inactive_as_with_asid_head. Must be acquired before as_t mutex. */
 SPINLOCK_INITIALIZE(as_lock);
 /**
  * This list contains address spaces that are not active on any
  * processor and that have valid ASID.
  */
 LIST_INITIALIZE(inactive_as_with_asid_head);
 /** Kernel address space. */
 as_t *AS_KERNEL = NULL;
 static int area_flags_to_page_flags(int aflags);
 static int get_area_flags(as_area_t *a);
 static as_area_t *find_area_and_lock(as_t *as, __address va);
 static bool check_area_conflicts(as_t *as, __address va, size_t size, as_area_t *avoid_area);
+int used_space_insert(as_area_t *a, __address page, count_t count);
+int used_space_remove(as_area_t *a, __address page, count_t count);
 /** Initialize address space subsystem. */
 void as_init(void)
+{
     as_arch_init();
     AS_KERNEL = as_create(FLAG_AS_KERNEL);
     if (!AS_KERNEL)
         panic("can't create kernel address space\n");
+}
 /** Create address space.
+ *
  * @param flags Flags that influence way in wich the address space is created.
  */
 as_t *as_create(int flags)
+{
     as_t *as;
     as = (as_t *) malloc(sizeof(as_t), 0);
     link_initialize(&as->inactive_as_with_asid_link);
     mutex_initialize(&as->lock);
     btree_create(&as->as_area_btree);
     if (flags & FLAG_AS_KERNEL)
         as->asid = ASID_KERNEL;
     else
         as->asid = ASID_INVALID;
     as->refcount = 0;
     as->page_table = page_table_create(flags);
     return as;
+}
 /** Free Adress space */
 void as_free(as_t *as)
+{
     ASSERT(as->refcount == 0);
     /* TODO: free as_areas and other resources held by as */
     /* TODO: free page table */
     free(as);
+}
 /** Create address space area of common attributes.
+ *
  * The created address space area is added to the target address space.
+ *
  * @param as Target address space.
  * @param flags Flags of the area memory.
  * @param size Size of area.
  * @param base Base address of area.
  * @param attrs Attributes of the area.
+ *
  * @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)
+{
     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;
+    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;
+    }
     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) {
         int i;
         /*
          * Shrinking the area.
          * No need to check for overlaps.
          */
         for (i = pages; i < area->pages; i++) {
             pte_t *pte;
             /*
              * Releasing physical memory.
              * This depends on the fact that the memory was allocated using frame_alloc().
              */
             page_table_lock(as, false);
             pte = page_mapping_find(as, area->base + i*PAGE_SIZE);
             if (pte && PTE_VALID(pte)) {
                 __address frame;
                 ASSERT(PTE_PRESENT(pte));
                 frame = PTE_GET_FRAME(pte);
                 page_mapping_remove(as, area->base + i*PAGE_SIZE);
                 page_table_unlock(as, false);
                 frame_free(ADDR2PFN(frame));
             } else {
                 page_table_unlock(as, false);
+            }
+        }
         /*
          * Invalidate TLB's.
          */
         tlb_shootdown_start(TLB_INVL_PAGES, AS->asid, area->base + pages*PAGE_SIZE, area->pages - pages);
         tlb_invalidate_pages(AS->asid, area->base + pages*PAGE_SIZE, area->pages - pages);
         tlb_shootdown_finalize();
     } else {
         /*
          * Growing the area.
          * Check for overlaps with other address space areas.
          */
         if (!check_area_conflicts(as, address, pages * PAGE_SIZE, area)) {
             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;
     int i;
     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;
     for (i = 0; i < area->pages; i++) {
         pte_t *pte;
         /*
          * Releasing physical memory.
          * Areas mapping memory-mapped devices are treated differently than
          * areas backing frame_alloc()'ed memory.
          */
         page_table_lock(as, false);
         pte = page_mapping_find(as, area->base + i*PAGE_SIZE);
         if (pte && PTE_VALID(pte)) {
             ASSERT(PTE_PRESENT(pte));
             page_mapping_remove(as, area->base + i*PAGE_SIZE);
             if (area->flags & AS_AREA_DEVICE) {
                 __address frame;
                 frame = PTE_GET_FRAME(pte);
                 frame_free(ADDR2PFN(frame));
+            }
             page_table_unlock(as, false);
         } else {
             page_table_unlock(as, false);
+        }
+    }
     /*
      * 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;
     mutex_unlock(&area->lock);
     /*
      * Remove the empty area from address space.
      */
     btree_remove(&AS->as_area_btree, base, NULL);
     free(area);
     mutex_unlock(&AS->lock);
     interrupts_restore(ipl);
     return 0;
+}
 /** Steal address space area from another task.
+ *
  * Address space area is stolen from another task
  * Moreover, any existing mapping
  * is copied as well, providing thus a mechanism
  * for sharing group of pages. The source address
  * space area and any associated mapping is preserved.
+ *
  * @param src_task Pointer of source task
  * @param src_base Base address of the source address space area.
  * @param acc_size Expected size of the source area
  * @param dst_base Target base address
+ *
  * @return Zero on success or ENOENT if there is no such task or
  *     if there is no such address space area,
  *     EPERM if there was a problem in accepting the area or
  *     ENOMEM if there was a problem in allocating destination
  *     address space area.
  */
 int as_area_steal(task_t *src_task, __address src_base, size_t acc_size,
           __address dst_base)
+{
     ipl_t ipl;
     count_t i;
     as_t *src_as;
     int src_flags;
     size_t src_size;
     as_area_t *src_area, *dst_area;
     ipl = interrupts_disable();
     spinlock_lock(&src_task->lock);
     src_as = src_task->as;
     mutex_lock(&src_as->lock);
     src_area = find_area_and_lock(src_as, src_base);
     if (!src_area) {
         /*
          * Could not find the source address space area.
          */
         spinlock_unlock(&src_task->lock);
         mutex_unlock(&src_as->lock);
         interrupts_restore(ipl);
         return ENOENT;
+    }
     src_size = src_area->pages * PAGE_SIZE;
     src_flags = src_area->flags;
     mutex_unlock(&src_area->lock);
     mutex_unlock(&src_as->lock);
     if (src_size != acc_size) {
         spinlock_unlock(&src_task->lock);
         interrupts_restore(ipl);
         return EPERM;
+    }
     /*
      * Create copy of the source address space area.
      * The destination area is created with AS_AREA_ATTR_PARTIAL
      * attribute set which prevents race condition with
      * preliminary as_page_fault() calls.
      */
     dst_area = as_area_create(AS, src_flags, src_size, dst_base, AS_AREA_ATTR_PARTIAL);
     if (!dst_area) {
         /*
          * Destination address space area could not be created.
          */
         spinlock_unlock(&src_task->lock);
         interrupts_restore(ipl);
         return ENOMEM;
+    }
     spinlock_unlock(&src_task->lock);
     /*
      * Avoid deadlock by first locking the address space with lower address.
      */
     if (AS < src_as) {
         mutex_lock(&AS->lock);
         mutex_lock(&src_as->lock);
     } else {
         mutex_lock(&AS->lock);
         mutex_lock(&src_as->lock);
+    }
     for (i = 0; i < SIZE2FRAMES(src_size); i++) {
         pte_t *pte;
         __address frame;
         page_table_lock(src_as, false);
         pte = page_mapping_find(src_as, src_base + i*PAGE_SIZE);
         if (pte && PTE_VALID(pte)) {
             ASSERT(PTE_PRESENT(pte));
             frame = PTE_GET_FRAME(pte);
             if (!(src_flags & AS_AREA_DEVICE))
                 frame_reference_add(ADDR2PFN(frame));
             page_table_unlock(src_as, false);
         } else {
             page_table_unlock(src_as, false);
             continue;
+        }
         page_table_lock(AS, false);
         page_mapping_insert(AS, dst_base + i*PAGE_SIZE, frame, area_flags_to_page_flags(src_flags));
         page_table_unlock(AS, false);
+    }
     /*
      * Now the destination address space area has been
      * fully initialized. Clear the AS_AREA_ATTR_PARTIAL
      * attribute.
      */
     mutex_lock(&dst_area->lock);
     dst_area->attributes &= ~AS_AREA_ATTR_PARTIAL;
     mutex_unlock(&dst_area->lock);
     mutex_unlock(&AS->lock);
     mutex_unlock(&src_as->lock);
     interrupts_restore(ipl);
     return 0;
+}
 /** Initialize mapping for one page of address space.
+ *
  * This functions maps 'page' to 'frame' according
  * to attributes of the address space area to
  * wich 'page' belongs.
+ *
  * @param as Target address space.
  * @param page Virtual page within the area.
  * @param frame Physical frame to which page will be mapped.
  */
 void as_set_mapping(as_t *as, __address page, __address frame)
+{
     as_area_t *area;
     ipl_t ipl;
     ipl = interrupts_disable();
     page_table_lock(as, true);
     area = find_area_and_lock(as, page);
     if (!area) {
         panic("page not part of any as_area\n");
+    }
     page_mapping_insert(as, page, frame, get_area_flags(area));
     mutex_unlock(&area->lock);
     page_table_unlock(as, true);
     interrupts_restore(ipl);
+}
 /** Handle page fault within the current address space.
+ *
  * This is the high-level page fault handler.
  * Interrupts are assumed disabled.
+ *
  * @param page Faulting page.
  * @param istate Pointer to interrupted state.
+ *
  * @return 0 on page fault, 1 on success or 2 if the fault was caused by copy_to_uspace() or copy_from_uspace().
  */
 int as_page_fault(__address page, istate_t *istate)
+{
     pte_t *pte;
     as_area_t *area;
     __address frame;
     if (!THREAD)
         return 0;
     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;
+    }
     ASSERT(!(area->flags & AS_AREA_DEVICE));
     page_table_lock(AS, false);
     /*
      * To avoid race condition between two page faults
      * on the same address, we need to make sure
      * the mapping has not been already inserted.
      */
     if ((pte = page_mapping_find(AS, page))) {
         if (PTE_PRESENT(pte)) {
             page_table_unlock(AS, false);
             mutex_unlock(&area->lock);
             mutex_unlock(&AS->lock);
             return 1;
+        }
+    }
     /*
      * In general, there can be several reasons that
      * can have caused this fault.
+     *
      * - non-existent mapping: the area is a scratch
      *   area (e.g. stack) and so far has not been
      *   allocated a frame for the faulting page
+     *
      * - non-present mapping: another possibility,
      *   currently not implemented, would be frame
      *   reuse; when this becomes a possibility,
      *   do not forget to distinguish between
      *   the different causes
      */
     frame = PFN2ADDR(frame_alloc(ONE_FRAME, 0));
     memsetb(PA2KA(frame), FRAME_SIZE, 0);
     /*
      * Map 'page' to 'frame'.
      * Note that TLB shootdown is not attempted as only new information is being
      * inserted into page tables.
      */
     page_mapping_insert(AS, page, frame, get_area_flags(area));
     page_table_unlock(AS, false);
     mutex_unlock(&area->lock);
     mutex_unlock(&AS->lock);
     return AS_PF_OK;
 page_fault:
     if (!THREAD)
         return AS_PF_FAULT;
     if (THREAD->in_copy_from_uspace) {
         THREAD->in_copy_from_uspace = false;
         istate_set_retaddr(istate, (__address) &memcpy_from_uspace_failover_address);
     } else if (THREAD->in_copy_to_uspace) {
         THREAD->in_copy_to_uspace = false;
         istate_set_retaddr(istate, (__address) &memcpy_to_uspace_failover_address);
     } else {
         return AS_PF_FAULT;
+    }
     return AS_PF_DEFER;
+}
 /** Switch address spaces.
+ *
  * Note that this function cannot sleep as it is essentially a part of
  * the scheduling. Sleeping here would lead to deadlock on wakeup.
+ *
  * @param old Old address space or NULL.
  * @param new New address space.
  */
 void as_switch(as_t *old, as_t *new)
+{
     ipl_t ipl;
     bool needs_asid = false;
     ipl = interrupts_disable();
     spinlock_lock(&as_lock);
     /*
      * First, take care of the old address space.
      */
     if (old) {
         mutex_lock_active(&old->lock);
         ASSERT(old->refcount);
         if((--old->refcount == 0) && (old != AS_KERNEL)) {
             /*
              * The old address space is no longer active on
              * any processor. It can be appended to the
              * list of inactive address spaces with assigned
              * ASID.
              */
              ASSERT(old->asid != ASID_INVALID);
              list_append(&old->inactive_as_with_asid_link, &inactive_as_with_asid_head);
+        }
         mutex_unlock(&old->lock);
+    }
     /*
      * Second, prepare the new address space.
      */
     mutex_lock_active(&new->lock);
     if ((new->refcount++ == 0) && (new != AS_KERNEL)) {
         if (new->asid != ASID_INVALID)
             list_remove(&new->inactive_as_with_asid_link);
         else
             needs_asid = true;  /* defer call to asid_get() until new->lock is released */
+    }
     SET_PTL0_ADDRESS(new->page_table);
     mutex_unlock(&new->lock);
     if (needs_asid) {
         /*
          * Allocation of new ASID was deferred
          * until now in order to avoid deadlock.
          */
         asid_t asid;
         asid = asid_get();
         mutex_lock_active(&new->lock);
         new->asid = asid;
         mutex_unlock(&new->lock);
+    }
     spinlock_unlock(&as_lock);
     interrupts_restore(ipl);
     /*
      * Perform architecture-specific steps.
      * (e.g. write ASID to hardware register etc.)
      */
     as_install_arch(new);
     AS = new;
+}
 /** Convert address space area flags to page flags.
+ *
  * @param aflags Flags of some address space area.
+ *
  * @return Flags to be passed to page_mapping_insert().
  */
 int area_flags_to_page_flags(int aflags)
+{
     int flags;
     flags = PAGE_USER | PAGE_PRESENT;
     if (aflags & AS_AREA_READ)
         flags |= PAGE_READ;
     if (aflags & AS_AREA_WRITE)
         flags |= PAGE_WRITE;
     if (aflags & AS_AREA_EXEC)
         flags |= PAGE_EXEC;
     if (!(aflags & AS_AREA_DEVICE))
         flags |= PAGE_CACHEABLE;
     return flags;
+}
 /** Compute flags for virtual address translation subsytem.
+ *
  * The address space area must be locked.
  * Interrupts must be disabled.
+ *
  * @param a Address space area.
+ *
  * @return Flags to be used in page_mapping_insert().
  */
 int get_area_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_t) 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_t) 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_t) 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_t) 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_t) 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_t) 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_t) 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 right 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_t) 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_t) 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_t) 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_t) 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);
+        } 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_t) 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_t) count;
+                return 1;
+            } else if (page + count*PAGE_SIZE < left_pg + left_cnt*PAGE_SIZE) {
+                count_t new_cnt = (left_pg + left_cnt*PAGE_SIZE) - (page + count*PAGE_SIZE);
+                /*
+                 * 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.
+                 */
+                node->value[node->keys - 1] -= (count_t) 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_t) count;
+                return 1;
+            } else if (page + count*PAGE_SIZE < left_pg + left_cnt*PAGE_SIZE) {
+                count_t new_cnt = (left_pg + left_cnt*PAGE_SIZE) - (page + count*PAGE_SIZE);
+                /*
+                 * 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.
+                 */
+                leaf->value[leaf->keys - 1] -= (count_t) 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_t) count;
+                    return 1;
+                } else if (page + count*PAGE_SIZE < left_pg + left_cnt*PAGE_SIZE) {
+                    count_t new_cnt = (left_pg + left_cnt*PAGE_SIZE) - (page + count*PAGE_SIZE);
+                    /*
+                     * 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.
+                     */
+                    leaf->value[i - 1] -= (count_t) 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);
+}
 /*
  * 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))
         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);
+}

Subversion Repositories HelenOS-historic

(root)/kernel/trunk/generic/src/mm/as.c – Rev 1383 → 1387