Changeset 00b595b in mainline

Timestamp:

2006-05-27T21:53:24Z (19 years ago)

Author:

Jakub Jermar <jakub@…>

Branches:

lfn, master, serial, ticket/834-toolchain-update, topic/msim-upgrade, topic/simplify-dev-export

Children:

46fc2f9

Parents:

127c957b

Message:

Support for sharing address space areas backed up by ELF image.

Location:

generic/src/mm

Files:

• backend_anon.c (modified) (1 diff)
• backend_elf.c (modified) (8 diffs)

generic/src/mm/backend_anon.c ¶

@@ -162 +162 @@
  * to the pagemap. Page faults will primarily search for frames there.
  *
- * The address space area and page tables must be already locked.
+ * The address space and address space area must be already locked.
  *
  * @param area Address space area to be shared.

generic/src/mm/backend_elf.c ¶

@@ -39 +39 @@
 #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>
@@ -46 +49 @@
 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
 };
 
@@ -67 +71 @@
         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;
@@ -77 +82 @@
         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) {
@@ -90 +132 @@
                         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);
@@ -102 +150 @@
                 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;
@@ -113 +167 @@
                 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))
-                panic("Could not insert used space.\n");
+        if (!used_space_insert(area, ALIGN_DOWN(addr, PAGE_SIZE), 1))
+                panic("Could not insert used space.\n");
 
         return AS_PF_OK;
@@ -159 +222 @@
         }
 }
+
+/** 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);
+}