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

 #include <arch/mm/page.h>
 #include <genarch/mm/page_pt.h>
 #include <genarch/mm/page_ht.h>
 #include <mm/asid.h>
 #include <arch/mm/asid.h>
-#include <arch/types.h>
-#include <typedefs.h>
 #include <synch/spinlock.h>
-#include <config.h>
 #include <adt/list.h>
 #include <adt/btree.h>
-#include <panic.h>
+#include <proc/task.h>
 #include <arch/asm.h>
+#include <panic.h>
 #include <debug.h>
+#include <print.h>
 #include <memstr.h>
 #include <macros.h>
 #include <arch.h>
-#include <print.h>
+#include <errno.h>
+#include <config.h>
+#include <arch/types.h>
+#include <typedefs.h>
 as_operations_t *as_operations = NULL;
 /** Address space lock. It protects inactive_as_with_asid_head. */
 SPINLOCK_INITIALIZE(as_lock);
 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);
 /** Initialize address space subsystem. */
     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 address on success, (__address) -1 otherwise.
+ */
+__address as_area_resize(as_t *as, __address address, size_t size, int flags)
+{
+    as_area_t *area = NULL;
+    ipl_t ipl;
+    size_t pages;
+    ipl = interrupts_disable();
+    spinlock_lock(&as->lock);
+    /*
+     * Locate the area.
+     */
+    area = find_area_and_lock(as, address);
+    if (!area) {
+        spinlock_unlock(&as->lock);
+        interrupts_restore(ipl);
+        return (__address) -1;
+    }
+    if (area->flags & AS_AREA_DEVICE) {
+        /*
+         * Remapping of address space areas associated
+         * with memory mapped devices is not supported.
+         */
+        spinlock_unlock(&area->lock);
+        spinlock_unlock(&as->lock);
+        interrupts_restore(ipl);
+        return (__address) -1;
+    }
+    pages = SIZE2FRAMES((address - area->base) + size);
+    if (!pages) {
+        /*
+         * Zero size address space areas are not allowed.
+         */
+        spinlock_unlock(&area->lock);
+        spinlock_unlock(&as->lock);
+        interrupts_restore(ipl);
+        return (__address) -1;
+    }
+    if (pages < area->pages) {
+        int i;
+        /*
+         * Shrinking the area.
+         * No need to check for overlaps.
+         */
+        for (i = pages; i < area->pages; i++) {
+            pte_t *pte;
+            /*
+             * Releasing physical memory.
+             * This depends on the fact that the memory was allocated using frame_alloc().
+             */
+            page_table_lock(as, false);
+            pte = page_mapping_find(as, area->base + i*PAGE_SIZE);
+            if (pte && PTE_VALID(pte)) {
+                __address frame;
+                ASSERT(PTE_PRESENT(pte));
+                frame = PTE_GET_FRAME(pte);
+                page_mapping_remove(as, area->base + i*PAGE_SIZE);
+                page_table_unlock(as, false);
+                frame_free(ADDR2PFN(frame));
+            } else {
+                page_table_unlock(as, false);
+            }
+        }
+        /*
+         * Invalidate TLB's.
+         */
+        tlb_shootdown_start(TLB_INVL_PAGES, AS->asid, area->base + pages*PAGE_SIZE, area->pages - pages);
+        tlb_invalidate_pages(AS->asid, area->base + pages*PAGE_SIZE, area->pages - pages);
+        tlb_shootdown_finalize();
+    } else {
+        /*
+         * Growing the area.
+         * Check for overlaps with other address space areas.
+         */
+        if (!check_area_conflicts(as, address, pages * PAGE_SIZE, area)) {
+            spinlock_unlock(&area->lock);
+            spinlock_unlock(&as->lock);
+            interrupts_restore(ipl);
+            return (__address) -1;
+        }
+    }
+    area->pages = pages;
+    spinlock_unlock(&area->lock);
+    spinlock_unlock(&as->lock);
+    interrupts_restore(ipl);
+    return address;
+}
+/** Send address space area to another task.
+ *
+ * Address space area is sent to the specified task.
+ * If the destination task is willing to accept the
+ * area, a new area is created according to the
+ * source area. 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 id Task ID of the accepting task.
+ * @param base Base address of the source address space area.
+ * @param size Size of the source address space area.
+ * @param flags Flags of the source address space area.
+ *
+ * @return 0 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_send(task_id_t id, __address base, size_t size, int flags)
+{
+    ipl_t ipl;
+    task_t *t;
+    count_t i;
+    as_t *as;
+    __address dst_base;
+    ipl = interrupts_disable();
+    spinlock_lock(&tasks_lock);
+    t = task_find_by_id(id);
+    if (!NULL) {
+        spinlock_unlock(&tasks_lock);
+        interrupts_restore(ipl);
+        return ENOENT;
+    }
+    spinlock_lock(&t->lock);
+    spinlock_unlock(&tasks_lock);
+    as = t->as;
+    dst_base = (__address) t->accept_arg.base;
+    if (as == AS) {
+        /*
+         * The two tasks share the entire address space.
+         * Return error since there is no point in continuing.
+         */
+        spinlock_unlock(&t->lock);
+        interrupts_restore(ipl);
+        return EPERM;
+    }
+    if ((t->accept_arg.task_id != TASK->taskid) || (t->accept_arg.size != size) ||
+        (t->accept_arg.flags != flags)) {
+        /*
+         * Discrepancy in either task ID, size or flags.
+         */
+        spinlock_unlock(&t->lock);
+        interrupts_restore(ipl);
+        return EPERM;
+    }
+    /*
+     * Create copy of the address space area.
+     */
+    if (!as_area_create(as, flags, size, dst_base)) {
+        /*
+         * Destination address space area could not be created.
+         */
+        spinlock_unlock(&t->lock);
+        interrupts_restore(ipl);
+        return ENOMEM;
+    }
+    /*
+     * NOTE: we have just introduced a race condition.
+     * The destination task can try to attempt the newly
+     * created area before its mapping is copied from
+     * the source address space area. In result, frames
+     * can get lost.
+     *
+     * Currently, this race is not solved, but one of the
+     * possible solutions would be to sleep in as_page_fault()
+     * when this situation is detected.
+     */
+    memsetb((__address) &t->accept_arg, sizeof(as_area_acptsnd_arg_t), 0);
+    spinlock_unlock(&t->lock);
+    /*
+     * Avoid deadlock by first locking the address space with lower address.
+     */
+    if (as < AS) {
+        spinlock_lock(&as->lock);
+        spinlock_lock(&AS->lock);
+    } else {
+        spinlock_lock(&AS->lock);
+        spinlock_lock(&as->lock);
+    }
+    for (i = 0; i < SIZE2FRAMES(size); i++) {
+        pte_t *pte;
+        __address frame;
+        page_table_lock(AS, false);
+        pte = page_mapping_find(AS, base + i*PAGE_SIZE);
+        if (pte && PTE_VALID(pte)) {
+            ASSERT(PTE_PRESENT(pte));
+            frame = PTE_GET_FRAME(pte);
+            if (!(flags & AS_AREA_DEVICE)) {
+                /* TODO: increment frame reference count */
+            }
+            page_table_unlock(AS, false);
+        } else {
+            page_table_unlock(AS, false);
+            continue;
+        }
+        page_table_lock(as, false);
+        page_mapping_insert(as, dst_base + i*PAGE_SIZE, frame, area_flags_to_page_flags(flags));
+        page_table_unlock(as, false);
+    }
+    spinlock_unlock(&AS->lock);
+    spinlock_unlock(&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.
     as_install_arch(new);
     AS = new;
+}
-/** Compute flags for virtual address translation subsytem.
+/** Convert address space area flags to page flags.
+ *
- * The address space area must be locked.
- * Interrupts must be disabled.
- *
- * @param a Address space area.
+ * @param aflags Flags of some address space area.
+ *
- * @return Flags to be used in page_mapping_insert().
+ * @return Flags to be passed to page_mapping_insert().
  */
-int get_area_flags(as_area_t *a)
+int area_flags_to_page_flags(int aflags)
+{
     int flags;
     flags = PAGE_USER | PAGE_PRESENT;
-    if (a->flags & AS_AREA_READ)
+    if (aflags & AS_AREA_READ)
         flags |= PAGE_READ;
-    if (a->flags & AS_AREA_WRITE)
+    if (aflags & AS_AREA_WRITE)
         flags |= PAGE_WRITE;
-    if (a->flags & AS_AREA_EXEC)
+    if (aflags & AS_AREA_EXEC)
         flags |= PAGE_EXEC;
-    if (!(a->flags & AS_AREA_DEVICE))
+    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.
+ *
     ASSERT(as_operations->page_table_unlock);
     as_operations->page_table_unlock(as, unlock);
+}
-/** Find address space area and change it.
- *
- * @param as Address space.
- * @param address Virtual address belonging to the area to be changed. Must be page-aligned.
- * @param size New size of the virtual memory block starting at address.
- * @param flags Flags influencing the remap operation. Currently unused.
- *
- * @return address on success, (__address) -1 otherwise.
- */
-__address as_area_resize(as_t *as, __address address, size_t size, int flags)
-{
-    as_area_t *area = NULL;
-    ipl_t ipl;
-    size_t pages;
-    ipl = interrupts_disable();
-    spinlock_lock(&as->lock);
-    /*
-     * Locate the area.
-     */
-    area = find_area_and_lock(as, address);
-    if (!area) {
-        spinlock_unlock(&as->lock);
-        interrupts_restore(ipl);
-        return (__address) -1;
-    }
-    if (area->flags & AS_AREA_DEVICE) {
-        /*
-         * Remapping of address space areas associated
-         * with memory mapped devices is not supported.
-         */
-        spinlock_unlock(&area->lock);
-        spinlock_unlock(&as->lock);
-        interrupts_restore(ipl);
-        return (__address) -1;
-    }
-    pages = SIZE2FRAMES((address - area->base) + size);
-    if (!pages) {
-        /*
-         * Zero size address space areas are not allowed.
-         */
-        spinlock_unlock(&area->lock);
-        spinlock_unlock(&as->lock);
-        interrupts_restore(ipl);
-        return (__address) -1;
-    }
-    if (pages < area->pages) {
-        int i;
-        /*
-         * Shrinking the area.
-         * No need to check for overlaps.
-         */
-        for (i = pages; i < area->pages; i++) {
-            pte_t *pte;
-            /*
-             * Releasing physical memory.
-             * This depends on the fact that the memory was allocated using frame_alloc().
-             */
-            page_table_lock(as, false);
-            pte = page_mapping_find(as, area->base + i*PAGE_SIZE);
-            if (pte && PTE_VALID(pte)) {
-                __address frame;
-                ASSERT(PTE_PRESENT(pte));
-                frame = PTE_GET_FRAME(pte);
-                page_mapping_remove(as, area->base + i*PAGE_SIZE);
-                page_table_unlock(as, false);
-                frame_free(ADDR2PFN(frame));
-            } else {
-                page_table_unlock(as, false);
-            }
-        }
-        /*
-         * Invalidate TLB's.
-         */
-        tlb_shootdown_start(TLB_INVL_PAGES, AS->asid, area->base + pages*PAGE_SIZE, area->pages - pages);
-        tlb_invalidate_pages(AS->asid, area->base + pages*PAGE_SIZE, area->pages - pages);
-        tlb_shootdown_finalize();
-    } else {
-        /*
-         * Growing the area.
-         * Check for overlaps with other address space areas.
-         */
-        if (!check_area_conflicts(as, address, pages * PAGE_SIZE, area)) {
-            spinlock_unlock(&area->lock);
-            spinlock_unlock(&as->lock);
-            interrupts_restore(ipl);
-            return (__address) -1;
-        }
-    }
-    area->pages = pages;
-    spinlock_unlock(&area->lock);
-    spinlock_unlock(&as->lock);
-    interrupts_restore(ipl);
-    return address;
-}
 /** Find address space area and lock it.
+ *
  * The address space must be locked and interrupts must be disabled.
+ *
             KERNEL_ADDRESS_SPACE_START, KERNEL_ADDRESS_SPACE_END-KERNEL_ADDRESS_SPACE_START);
+    }
     return true;
+}
+/*
+ * 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))
+        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 as_area_resize(AS, address, size, 0);
+}
+/** Prepare task for accepting address space area from another task.
+ *
+ * @param uspace_accept_arg Accept structure passed from userspace.
+ *
+ * @return EPERM if the task ID encapsulated in @uspace_accept_arg references
+ *     TASK. Otherwise zero is returned.
+ */
+__native sys_as_area_accept(as_area_acptsnd_arg_t *uspace_accept_arg)
+{
+    as_area_acptsnd_arg_t arg;
+    copy_from_uspace(&arg, uspace_accept_arg, sizeof(as_area_acptsnd_arg_t));
+    if (!arg.size)
+        return (__native) EPERM;
+    if (arg.task_id == TASK->taskid) {
+        /*
+         * Accepting from itself is not allowed.
+         */
+        return (__native) EPERM;
+    }
+    memcpy(&TASK->accept_arg, &arg, sizeof(as_area_acptsnd_arg_t));
+        return 0;
+}
+/** Wrapper for as_area_send. */
+__native sys_as_area_send(as_area_acptsnd_arg_t *uspace_send_arg)
+{
+    as_area_acptsnd_arg_t arg;
+    copy_from_uspace(&arg, uspace_send_arg, sizeof(as_area_acptsnd_arg_t));
+    if (!arg.size)
+        return (__native) EPERM;
+    if (arg.task_id == TASK->taskid) {
+        /*
+         * Sending to itself is not allowed.
+         */
+        return (__native) EPERM;
+    }
+    return (__native) as_area_send(arg.task_id, (__address) arg.base, arg.size, arg.flags);
+}

Subversion Repositories HelenOS-historic

(root)/kernel/trunk/generic/src/mm/as.c – Rev 1233 → 1235