WebSVN – HelenOS-historic – Diff – /kernel/trunk/generic/src/lib/elf.c

 #include <mm/frame.h>
 #include <mm/slab.h>
 #include <align.h>
 #include <memstr.h>
 #include <macros.h>
+#include <arch.h>
 static char *error_codes[] = {
     "no error",
     "invalid image",
     "address space error",
 static int segment_header(elf_segment_header_t *entry, elf_header_t *elf, as_t *as);
 static int section_header(elf_section_header_t *entry, elf_header_t *elf, as_t *as);
 static int load_segment(elf_segment_header_t *entry, elf_header_t *elf, as_t *as);
+static int elf_page_fault(as_area_t *area, __address addr);
+static void elf_frame_free(as_area_t *area, __address page, __address frame);
+mem_backend_t elf_backend = {
+    .backend_page_fault = elf_page_fault,
+    .backend_frame_free = elf_frame_free
+};
 /** ELF loader
+ *
  * @param header Pointer to ELF header in memory
  * @param as Created and properly mapped address space
  * @return EE_OK on success
  * @return EE_OK on success, error code otherwise.
  */
 int load_segment(elf_segment_header_t *entry, elf_header_t *elf, as_t *as)
+{
     as_area_t *a;
-    int i, flags = 0;
+    int flags = 0;
-    size_t segment_size;
+    void *backend_data[2] = { elf, entry };
-    __u8 *segment;
     if (entry->p_align > 1) {
         if ((entry->p_offset % entry->p_align) != (entry->p_vaddr % entry->p_align)) {
             return EE_INVALID;
+        }
      * Check if the virtual address starts on page boundary.
      */
     if (ALIGN_UP(entry->p_vaddr, PAGE_SIZE) != entry->p_vaddr)
         return EE_UNSUPPORTED;
-    segment_size = ALIGN_UP(max(entry->p_filesz, entry->p_memsz), PAGE_SIZE);
-    if ((entry->p_flags & PF_W)) {
-        /* If writable, copy data (should be COW in the future) */
-        segment = malloc(segment_size, 0);
-        memsetb((__address) (segment + entry->p_filesz), segment_size - entry->p_filesz, 0);
-        memcpy(segment, (void *) (((__address) elf) + entry->p_offset), entry->p_filesz);
-    } else /* Map identically original data */
-        segment = ((void *) elf) + entry->p_offset;
-    a = as_area_create(as, flags, entry->p_memsz, entry->p_vaddr, AS_AREA_ATTR_NONE);
+    a = as_area_create(as, flags, entry->p_memsz, entry->p_vaddr, AS_AREA_ATTR_NONE, &elf_backend, backend_data);
     if (!a)
         return EE_MEMORY;
+    /*
-    for (i = 0; i < SIZE2FRAMES(entry->p_filesz); i++) {
+     * The segment will be mapped on demand by elf_page_fault().
-        as_set_mapping(as, entry->p_vaddr + i*PAGE_SIZE, KA2PA(((__address) segment) + i*PAGE_SIZE));
-    }
+     */
     return EE_OK;
+}
 /** Process section header.
+ *
         break;
+    }
     return EE_OK;
+}
+/** Service a page fault in the ELF backend address space area.
+ *
+ * The address space area and page tables must be already locked.
+ *
+ * @param area Pointer to the address space area.
+ * @param addr Faulting virtual address.
+ *
+ * @return AS_PF_FAULT on failure (i.e. page fault) or AS_PF_OK on success (i.e. serviced).
+ */
+int elf_page_fault(as_area_t *area, __address addr)
+{
+    elf_header_t *elf = (elf_header_t *) area->backend_data[0];
+    elf_segment_header_t *entry = (elf_segment_header_t *) area->backend_data[1];
+    __address base, frame;
+    index_t i;
+    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 (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
+         * only copied if the segment is writable so that there
+         * can be more instantions of the same memory ELF image
+         * used at a time. Note that this could be later done
+         * 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);
+        } else {
+            frame = KA2PA(base + i*FRAME_SIZE);
+        }
+    } else if (ALIGN_DOWN(addr, PAGE_SIZE) >= ALIGN_UP(entry->p_vaddr + entry->p_filesz, PAGE_SIZE)) {
+        /*
+         * This is the uninitialized portion of the segment.
+         * It is not physically present in the ELF image.
+         * To resolve the situation, a frame must be allocated
+         * and cleared.
+         */
+        frame = PFN2ADDR(frame_alloc(ONE_FRAME, 0));
+        memsetb(PA2KA(frame), FRAME_SIZE, 0);
+    } else {
+        size_t size;
+        /*
+         * The mixed case.
+         * The lower part is backed by the ELF image and
+         * the upper part is anonymous memory.
+         */
+        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);
+    }
+    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");
+    return AS_PF_OK;
+}
+/** Free a frame that is backed by the ELF backend.
+ *
+ * The address space area and page tables must be already locked.
+ *
+ * @param area Pointer to the address space area.
+ * @param page Page that is mapped to frame. Must be aligned to PAGE_SIZE.
+ * @param frame Frame to be released.
+ *
+ */
+void elf_frame_free(as_area_t *area, __address page, __address frame)
+{
+    elf_header_t *elf = (elf_header_t *) area->backend_data[0];
+    elf_segment_header_t *entry = (elf_segment_header_t *) area->backend_data[1];
+    __address base;
+    index_t i;
+    ASSERT((page >= entry->p_vaddr) && (page < entry->p_vaddr + entry->p_memsz));
+    i = (page - entry->p_vaddr) >> PAGE_WIDTH;
+    base = (__address) (((void *) elf) + entry->p_offset);
+    ASSERT(ALIGN_UP(base, FRAME_SIZE) == base);
+    if (page + PAGE_SIZE < ALIGN_UP(entry->p_vaddr + entry->p_filesz, PAGE_SIZE)) {
+        if (entry->p_flags & PF_W) {
+            /*
+             * Free the frame with the copy of writable segment data.
+             */
+            frame_free(ADDR2PFN(frame));
+        }
+    } else {
+        /*
+         * The frame is either anonymous memory or the mixed case (i.e. lower
+         * part is backed by the ELF image and the upper is anonymous).
+         * In any case, a frame needs to be freed.
+         */
+        frame_free(ADDR2PFN(frame));
+    }
+}

Subversion Repositories HelenOS-historic

(root)/kernel/trunk/generic/src/lib/elf.c – Rev 1264 → 1409