WebSVN – HelenOS-historic – Diff – /kernel/trunk/genarch/src/mm/page_pt.c

 /*
  * Copyright (C) 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.
  */
 #include <genarch/mm/page_pt.h>
 #include <mm/page.h>
 #include <mm/frame.h>
 #include <mm/as.h>
 #include <arch/mm/page.h>
 #include <arch/mm/as.h>
 #include <arch/types.h>
 #include <typedefs.h>
 #include <arch/asm.h>
 #include <memstr.h>
 static void pt_mapping_insert(as_t *as, __address page, __address frame, int flags);
 static void pt_mapping_remove(as_t *as, __address page);
 static pte_t *pt_mapping_find(as_t *as, __address page);
 page_mapping_operations_t pt_mapping_operations = {
     .mapping_insert = pt_mapping_insert,
     .mapping_remove = pt_mapping_remove,
     .mapping_find = pt_mapping_find
 };
 /** Map page to frame using hierarchical page tables.
+ *
  * Map virtual address 'page' to physical address 'frame'
  * using 'flags'.
+ *
  * The address space must be locked and interrupts must be disabled.
+ *
  * @param as Address space to wich page belongs.
  * @param page Virtual address of the page to be mapped.
  * @param frame Physical address of memory frame to which the mapping is done.
  * @param flags Flags to be used for mapping.
  */
 void pt_mapping_insert(as_t *as, __address page, __address frame, int flags)
+{
     pte_t *ptl0, *ptl1, *ptl2, *ptl3;
     __address newpt;
     ptl0 = (pte_t *) PA2KA((__address) as->page_table);
     if (GET_PTL1_FLAGS(ptl0, PTL0_INDEX(page)) & PAGE_NOT_PRESENT) {
         newpt = PA2KA(PFN2ADDR(frame_alloc(ONE_FRAME, FRAME_KA)));
         memsetb(newpt, PAGE_SIZE, 0);
         SET_PTL1_ADDRESS(ptl0, PTL0_INDEX(page), KA2PA(newpt));
         SET_PTL1_FLAGS(ptl0, PTL0_INDEX(page), PAGE_PRESENT | PAGE_USER | PAGE_EXEC | PAGE_CACHEABLE | PAGE_WRITE);
+    }
     ptl1 = (pte_t *) PA2KA(GET_PTL1_ADDRESS(ptl0, PTL0_INDEX(page)));
     if (GET_PTL2_FLAGS(ptl1, PTL1_INDEX(page)) & PAGE_NOT_PRESENT) {
         newpt = PA2KA(PFN2ADDR(frame_alloc(ONE_FRAME, FRAME_KA)));
         memsetb(newpt, PAGE_SIZE, 0);
         SET_PTL2_ADDRESS(ptl1, PTL1_INDEX(page), KA2PA(newpt));
         SET_PTL2_FLAGS(ptl1, PTL1_INDEX(page), PAGE_PRESENT | PAGE_USER | PAGE_EXEC | PAGE_CACHEABLE | PAGE_WRITE);
+    }
     ptl2 = (pte_t *) PA2KA(GET_PTL2_ADDRESS(ptl1, PTL1_INDEX(page)));
     if (GET_PTL3_FLAGS(ptl2, PTL2_INDEX(page)) & PAGE_NOT_PRESENT) {
         newpt = PA2KA(PFN2ADDR(frame_alloc(ONE_FRAME, FRAME_KA)));
         memsetb(newpt, PAGE_SIZE, 0);
         SET_PTL3_ADDRESS(ptl2, PTL2_INDEX(page), KA2PA(newpt));
         SET_PTL3_FLAGS(ptl2, PTL2_INDEX(page), PAGE_PRESENT | PAGE_USER | PAGE_EXEC | PAGE_CACHEABLE | PAGE_WRITE);
+    }
     ptl3 = (pte_t *) PA2KA(GET_PTL3_ADDRESS(ptl2, PTL2_INDEX(page)));
     SET_FRAME_ADDRESS(ptl3, PTL3_INDEX(page), frame);
     SET_FRAME_FLAGS(ptl3, PTL3_INDEX(page), flags);
+}
 /** Remove mapping of page from hierarchical page tables.
+ *
  * Remove any mapping of 'page' within address space 'as'.
  * TLB shootdown should follow in order to make effects of
  * this call visible.
+ *
+ * Empty page tables except PTL0 are freed.
+ *
  * The address space must be locked and interrupts must be disabled.
+ *
  * @param as Address space to wich page belongs.
  * @param page Virtual address of the page to be demapped.
  */
 void pt_mapping_remove(as_t *as, __address page)
+{
     pte_t *ptl0, *ptl1, *ptl2, *ptl3;
+    bool empty = true;
+    int i;
+    /*
+     * First, remove the mapping, if it exists.
+     */
     ptl0 = (pte_t *) PA2KA((__address) as->page_table);
     if (GET_PTL1_FLAGS(ptl0, PTL0_INDEX(page)) & PAGE_NOT_PRESENT)
         return;
     ptl1 = (pte_t *) PA2KA(GET_PTL1_ADDRESS(ptl0, PTL0_INDEX(page)));
     if (GET_PTL2_FLAGS(ptl1, PTL1_INDEX(page)) & PAGE_NOT_PRESENT)
         return;
     ptl2 = (pte_t *) PA2KA(GET_PTL2_ADDRESS(ptl1, PTL1_INDEX(page)));
     if (GET_PTL3_FLAGS(ptl2, PTL2_INDEX(page)) & PAGE_NOT_PRESENT)
         return;
     ptl3 = (pte_t *) PA2KA(GET_PTL3_ADDRESS(ptl2, PTL2_INDEX(page)));
     /* Destroy the mapping. Setting to PAGE_NOT_PRESENT is not sufficient. */
     memsetb((__address) &ptl3[PTL3_INDEX(page)], sizeof(pte_t), 0);
+    /*
+     * Second, free all empty tables along the way from PTL3 down to PTL0.
+     */
+    /* check PTL3 */
+    for (i = 0; i < PTL3_ENTRIES; i++) {
+        if (PTE_VALID(&ptl3[i])) {
+            empty = false;
+            break;
+        }
+    }
+    if (empty) {
+        /*
+         * PTL3 is empty.
+         * Release the frame and remove PTL3 pointer from preceding table.
+         */
+        frame_free(ADDR2PFN(KA2PA((__address) ptl3)));
+        if (PTL2_ENTRIES)
+            memsetb((__address) &ptl2[PTL2_INDEX(page)], sizeof(pte_t), 0);
+        else if (PTL1_ENTRIES)
+            memsetb((__address) &ptl1[PTL1_INDEX(page)], sizeof(pte_t), 0);
+        else
+            memsetb((__address) &ptl0[PTL0_INDEX(page)], sizeof(pte_t), 0);
+    } else {
+        /*
+         * PTL3 is not empty.
+         * Therefore, there must be a path from PTL0 to PTL3 and
+         * thus nothing to free in higher levels.
+         */
+        return;
+    }
+    /* check PTL2, empty is still true */
+    if (PTL2_ENTRIES) {
+        for (i = 0; i < PTL2_ENTRIES; i++) {
+            if (PTE_VALID(&ptl2[i])) {
+                empty = false;
+                break;
+            }
+        }
+        if (empty) {
+            /*
+             * PTL2 is empty.
+             * Release the frame and remove PTL2 pointer from preceding table.
+             */
+            frame_free(ADDR2PFN(KA2PA((__address) ptl2)));
+            if (PTL1_ENTRIES)
+                memsetb((__address) &ptl1[PTL1_INDEX(page)], sizeof(pte_t), 0);
+            else
+                memsetb((__address) &ptl0[PTL0_INDEX(page)], sizeof(pte_t), 0);
+        }
+        else {
+            /*
+             * PTL2 is not empty.
+             * Therefore, there must be a path from PTL0 to PTL2 and
+             * thus nothing to free in higher levels.
+             */
+            return;
+        }
+    }
+    /* check PTL1, empty is still true */
+    if (PTL1_ENTRIES) {
+        for (i = 0; i < PTL1_ENTRIES; i++) {
+            if (PTE_VALID(&ptl1[i])) {
+                empty = false;
+                break;
+            }
+        }
+        if (empty) {
+            /*
+             * PTL1 is empty.
+             * Release the frame and remove PTL1 pointer from preceding table.
+             */
+            frame_free(ADDR2PFN(KA2PA((__address) ptl1)));
+            memsetb((__address) &ptl0[PTL0_INDEX(page)], sizeof(pte_t), 0);
+        }
+    }
+}
 /** Find mapping for virtual page in hierarchical page tables.
+ *
  * Find mapping for virtual page.
+ *
  * The address space must be locked and interrupts must be disabled.
+ *
  * @param as Address space to which page belongs.
  * @param page Virtual page.
+ *
  * @return NULL if there is no such mapping; entry from PTL3 describing the mapping otherwise.
  */
 pte_t *pt_mapping_find(as_t *as, __address page)
+{
     pte_t *ptl0, *ptl1, *ptl2, *ptl3;
     ptl0 = (pte_t *) PA2KA((__address) as->page_table);
     if (GET_PTL1_FLAGS(ptl0, PTL0_INDEX(page)) & PAGE_NOT_PRESENT)
         return NULL;
     ptl1 = (pte_t *) PA2KA(GET_PTL1_ADDRESS(ptl0, PTL0_INDEX(page)));
     if (GET_PTL2_FLAGS(ptl1, PTL1_INDEX(page)) & PAGE_NOT_PRESENT)
         return NULL;
     ptl2 = (pte_t *) PA2KA(GET_PTL2_ADDRESS(ptl1, PTL1_INDEX(page)));
     if (GET_PTL3_FLAGS(ptl2, PTL2_INDEX(page)) & PAGE_NOT_PRESENT)
         return NULL;
     ptl3 = (pte_t *) PA2KA(GET_PTL3_ADDRESS(ptl2, PTL2_INDEX(page)));
     return &ptl3[PTL3_INDEX(page)];
+}

Subversion Repositories HelenOS-historic

(root)/kernel/trunk/genarch/src/mm/page_pt.c – Rev 826 → 832