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

 #include <arch/types.h>
 #include <typedefs.h>
 #include <mm/as.h>
 #include <mm/frame.h>
 #include <mm/slab.h>
+#include <mm/page.h>
+#include <genarch/mm/page_pt.h>
+#include <genarch/mm/page_ht.h>
 #include <align.h>
 #include <memstr.h>
 #include <macros.h>
 #include <arch.h>
 static int elf_page_fault(as_area_t *area, __address addr, pf_access_t access);
 static void elf_frame_free(as_area_t *area, __address page, __address frame);
+static void elf_share(as_area_t *area);
 mem_backend_t elf_backend = {
     .page_fault = elf_page_fault,
     .frame_free = elf_frame_free,
-    .share = NULL
+    .share = elf_share
 };
 /** Service a page fault in the ELF backend address space area.
+ *
  * The address space area and page tables must be already locked.
  */
 int elf_page_fault(as_area_t *area, __address addr, pf_access_t access)
+{
     elf_header_t *elf = area->backend_data.elf;
     elf_segment_header_t *entry = area->backend_data.segment;
+    btree_node_t *leaf;
     __address base, frame;
     index_t i;
     if (!as_area_check_access(area, access))
         return AS_PF_FAULT;
     ASSERT((addr >= entry->p_vaddr) && (addr < entry->p_vaddr + entry->p_memsz));
     i = (addr - entry->p_vaddr) >> PAGE_WIDTH;
     base = (__address) (((void *) elf) + entry->p_offset);
     ASSERT(ALIGN_UP(base, FRAME_SIZE) == base);
+    if (area->sh_info) {
+        bool found = false;
+        /*
+         * The address space area is shared.
+         */
+        mutex_lock(&area->sh_info->lock);
+        frame = (__address) btree_search(&area->sh_info->pagemap,
+            ALIGN_DOWN(addr, PAGE_SIZE) - area->base, &leaf);
+        if (!frame) {
+            int i;
+            /*
+             * Workaround for valid NULL address.
+             */
+            for (i = 0; i < leaf->keys; i++) {
+                if (leaf->key[i] == ALIGN_DOWN(addr, PAGE_SIZE)) {
+                    found = true;
+                    break;
+                }
+            }
+        }
+        if (frame || found) {
+            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");
+            mutex_unlock(&area->sh_info->lock);
+            return AS_PF_OK;
+        }
+    }
+    /*
+     * The area is either not shared or the pagemap does not contain the mapping.
+     */
     if (ALIGN_DOWN(addr, PAGE_SIZE) + PAGE_SIZE < entry->p_vaddr + entry->p_filesz) {
         /*
          * Initialized portion of the segment. The memory is backed
          * directly by the content of the ELF image. Pages are
          * as COW.
          */
         if (entry->p_flags & PF_W) {
             frame = PFN2ADDR(frame_alloc(ONE_FRAME, 0));
             memcpy((void *) PA2KA(frame), (void *) (base + i*FRAME_SIZE), FRAME_SIZE);
+            if (area->sh_info) {
+                btree_insert(&area->sh_info->pagemap, ALIGN_DOWN(addr, PAGE_SIZE) - area->base,
+                    (void *) frame, leaf);
+            }
         } else {
             frame = KA2PA(base + i*FRAME_SIZE);
+        }
     } else if (ALIGN_DOWN(addr, PAGE_SIZE) >= ALIGN_UP(entry->p_vaddr + entry->p_filesz, PAGE_SIZE)) {
         /*
          * To resolve the situation, a frame must be allocated
          * and cleared.
          */
         frame = PFN2ADDR(frame_alloc(ONE_FRAME, 0));
         memsetb(PA2KA(frame), FRAME_SIZE, 0);
+        if (area->sh_info) {
+            btree_insert(&area->sh_info->pagemap, ALIGN_DOWN(addr, PAGE_SIZE) - area->base,
+                (void *) frame, leaf);
+        }
     } else {
         size_t size;
         /*
          * The mixed case.
          * The lower part is backed by the ELF image and
          */
         size = entry->p_filesz - (i<<PAGE_WIDTH);
         frame = PFN2ADDR(frame_alloc(ONE_FRAME, 0));
         memsetb(PA2KA(frame) + size, FRAME_SIZE - size, 0);
         memcpy((void *) PA2KA(frame), (void *) (base + i*FRAME_SIZE), size);
+        if (area->sh_info) {
+            btree_insert(&area->sh_info->pagemap, ALIGN_DOWN(addr, PAGE_SIZE) - area->base,
+                (void *) frame, leaf);
+        }
+    }
+    if (area->sh_info)
+        mutex_unlock(&area->sh_info->lock);
     page_mapping_insert(AS, addr, frame, as_area_get_flags(area));
-        if (!used_space_insert(area, ALIGN_DOWN(addr, PAGE_SIZE), 1))
+    if (!used_space_insert(area, ALIGN_DOWN(addr, PAGE_SIZE), 1))
-                panic("Could not insert used space.\n");
+        panic("Could not insert used space.\n");
     return AS_PF_OK;
+}
 /** Free a frame that is backed by the ELF backend.
          * In any case, a frame needs to be freed.
          */
         frame_free(ADDR2PFN(frame));
+    }
+}
+/** Share ELF image backed address space area.
+ *
+ * If the area is writable, then all mapped pages are duplicated in the pagemap.
+ * Otherwise only portions of the area that are not backed by the ELF image
+ * are put into the pagemap.
+ *
+ * The address space and address space area must be locked prior to the call.
+ *
+ * @param area Address space area.
+ */
+void elf_share(as_area_t *area)
+{
+    elf_segment_header_t *entry = area->backend_data.segment;
+    link_t *cur;
+    btree_node_t *leaf, *node;
+    __address start_anon = entry->p_vaddr + entry->p_filesz;
+    /*
+     * Find the node in which to start linear search.
+     */
+    if (area->flags & AS_AREA_WRITE) {
+        node = list_get_instance(area->used_space.leaf_head.next, btree_node_t, leaf_link);
+    } else {
+        (void) btree_search(&area->sh_info->pagemap, start_anon, &leaf);
+        node = btree_leaf_node_left_neighbour(&area->sh_info->pagemap, leaf);
+        if (!node)
+            node = leaf;
+    }
+    /*
+     * Copy used anonymous portions of the area to sh_info's page map.
+     */
+    mutex_lock(&area->sh_info->lock);
+    for (cur = &node->leaf_link; cur != &area->used_space.leaf_head; cur = cur->next) {
+        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;
+            /*
+             * Skip read-only areas of used space that are backed
+             * by the ELF image.
+             */
+            if (!(area->flags & AS_AREA_WRITE))
+                if (base + count*PAGE_SIZE <= start_anon)
+                    continue;
+            for (j = 0; j < count; j++) {
+                pte_t *pte;
+                /*
+                 * Skip read-only pages that are backed by the ELF image.
+                 */
+                if (!(area->flags & AS_AREA_WRITE))
+                    if (base + (j + 1)*PAGE_SIZE <= start_anon)
+                        continue;
+                page_table_lock(area->as, false);
+                pte = page_mapping_find(area->as, base + j*PAGE_SIZE);
+                ASSERT(pte && PTE_VALID(pte) && PTE_PRESENT(pte));
+                btree_insert(&area->sh_info->pagemap, (base + j*PAGE_SIZE) - area->base,
+                    (void *) PTE_GET_FRAME(pte), NULL);
+                page_table_unlock(area->as, false);
+            }
+        }
+    }
+    mutex_unlock(&area->sh_info->lock);
+}

Subversion Repositories HelenOS-historic

(root)/kernel/trunk/generic/src/mm/backend_elf.c – Rev 1425 → 1426