Changeset d91488d in mainline

Timestamp:

2018-11-21T09:16:16Z (6 years ago)

Author:

Jiri Svoboda <jiri@…>

Branches:

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

Children:

a91c555f

Parents:

0705fc5

git-author:

Jiri Svoboda <jiri@…> (2018-11-20 20:14:06)

git-committer:

Jiri Svoboda <jiri@…> (2018-11-21 09:16:16)

Message:

Fix endless loop in elf_share() walking the wrong B+tree. Fix ELF areas shared to a different address than in the originating task.

Location:

kernel/generic

Files:

• include/mm/as.h (modified) (1 diff)
• src/lib/elf.c (modified) (2 diffs)
• src/mm/backend_elf.c (modified) (7 diffs)

kernel/generic/include/mm/as.h

@@ -179 +179 @@
         /** elf_backend members */
         struct {
+                uintptr_t elf_base;
                 elf_header_t *elf;
                 elf_segment_header_t *segment;

kernel/generic/src/lib/elf.c

@@ -142 +142 @@
 {
         mem_backend_data_t backend_data;
-        backend_data.elf = elf;
-        backend_data.segment = entry;
 
         if (entry->p_align > 1) {
@@ -172 +170 @@
         size_t mem_sz = entry->p_memsz + (entry->p_vaddr - base);
 
+        backend_data.elf_base = base;
+        backend_data.elf = elf;
+        backend_data.segment = entry;
+
         as_area_t *area = as_area_create(as, flags, mem_sz,
             AS_AREA_ATTR_NONE, &elf_backend, &backend_data, &base, 0);

kernel/generic/src/mm/backend_elf.c

@@ -96 +96 @@
 }
 
+/** Get page number in the task where the ELF page originates from.
+ *
+ * The ELF page can be shared to a different address than it originated from,
+ * but we need the originating address since that corresponds to the ELF's
+ * virtual addesses.
+ *
+ * @param area Area in which the page resides
+ * @param page Virtual address of the page in @a area
+ * @return Virtual address of the page in the origin address space
+ */
+static uintptr_t elf_orig_page(as_area_t *area, uintptr_t page)
+{
+        return page - area->base + area->backend_data.elf_base;
+}
+
 bool elf_create(as_area_t *area)
 {
@@ -152 +167 @@
                     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);
+                (void) btree_search(&area->used_space, start_anon, &leaf);
+                node = btree_leaf_node_left_neighbour(&area->used_space, leaf);
                 if (!node)
                         node = leaf;
@@ -258 +272 @@
         uintptr_t kpage;
         uintptr_t start_anon;
+        uintptr_t elfpage;
         size_t i;
         bool dirty = false;
@@ -265 +280 @@
         assert(IS_ALIGNED(upage, PAGE_SIZE));
 
+        elfpage = elf_orig_page(area, upage);
+
         if (!as_area_check_access(area, access))
                 return AS_PF_FAULT;
 
-        if (upage < ALIGN_DOWN(entry->p_vaddr, PAGE_SIZE))
+        if (elfpage < ALIGN_DOWN(entry->p_vaddr, PAGE_SIZE))
                 return AS_PF_FAULT;
 
-        if (upage >= entry->p_vaddr + entry->p_memsz)
+        if (elfpage >= entry->p_vaddr + entry->p_memsz)
                 return AS_PF_FAULT;
 
-        i = (upage - ALIGN_DOWN(entry->p_vaddr, PAGE_SIZE)) >> PAGE_WIDTH;
+        i = (elfpage - ALIGN_DOWN(entry->p_vaddr, PAGE_SIZE)) >>
+            PAGE_WIDTH;
         base = (uintptr_t)
             (((void *) elf) + ALIGN_DOWN(entry->p_offset, PAGE_SIZE));
@@ -320 +338 @@
          * mapping.
          */
-        if (upage >= entry->p_vaddr && upage + PAGE_SIZE <= start_anon) {
+        if (elfpage >= entry->p_vaddr && elfpage + PAGE_SIZE <= start_anon) {
                 /*
                  * 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
+                 * can be more instances of the same memory ELF image
                  * used at a time. Note that this could be later done
                  * as COW.
@@ -351 +369 @@
                         frame = PTE_GET_FRAME(&pte);
                 }
-        } else if (upage >= start_anon) {
+        } else if (elfpage >= start_anon) {
                 /*
                  * This is the uninitialized portion of the segment.
@@ -424 +442 @@
         elf_segment_header_t *entry = area->backend_data.segment;
         uintptr_t start_anon;
+        uintptr_t elfpage;
 
         assert(page_table_locked(area->as));
         assert(mutex_locked(&area->lock));
 
-        assert(page >= ALIGN_DOWN(entry->p_vaddr, PAGE_SIZE));
-        assert(page < entry->p_vaddr + entry->p_memsz);
+        elfpage = elf_orig_page(area, page);
+
+        assert(elfpage >= ALIGN_DOWN(entry->p_vaddr, PAGE_SIZE));
+        assert(elfpage < entry->p_vaddr + entry->p_memsz);
 
         start_anon = entry->p_vaddr + entry->p_filesz;
 
-        if (page >= entry->p_vaddr && page + PAGE_SIZE <= start_anon) {
+        if (elfpage >= entry->p_vaddr && elfpage + PAGE_SIZE <= start_anon) {
                 if (entry->p_flags & PF_W) {
                         /*