vdso: Separate vdso_init() on dump/restore

On dump we only need vdso_pfn to be filled,
on restore we need filled symtables.

That means, that we can omit filling symtables on dump,
which also means no need in calling compat_vdso_helper
process with fork(), pipe(), read(), write() and so on syscalls.
Reviewed-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Dmitry Safonov <dsafonov@virtuozzo.com>
Signed-off-by: Andrei Vagin <avagin@virtuozzo.com>

criu/cr-dump.c

@@ -1562,7 +1562,7 @@ int cr_pre_dump_tasks(pid_t pid)
 	if (cpu_init())
 		goto err;
 
-	if (vdso_init())
+	if (vdso_init_dump())
 		goto err;
 
 	if (connect_to_page_server_to_send() < 0)
@@ -1738,7 +1738,7 @@ int cr_dump_tasks(pid_t pid)
 	if (cpu_init())
 		goto err;
 
-	if (vdso_init())
+	if (vdso_init_dump())
 		goto err;
 
 	if (cgp_init(opts.cgroup_props,

criu/cr-restore.c

@@ -2205,7 +2205,7 @@ int cr_restore_tasks(void)
 	if (cpu_init() < 0)
 		goto err;
 
-	if (vdso_init())
+	if (vdso_init_restore())
 		goto err;
 
 	if (opts.cpu_cap & (CPU_CAP_INS | CPU_CAP_CPU)) {

criu/include/vdso.h

@@ -13,7 +13,8 @@
 extern struct vdso_maps vdso_maps;
 extern struct vdso_maps vdso_maps_compat;
 
-extern int vdso_init(void);
+extern int vdso_init_dump(void);
+extern int vdso_init_restore(void);
 
 extern int parasite_fixup_vdso(struct parasite_ctl *ctl, pid_t pid,
 			       struct vm_area_list *vma_area_list);
@@ -25,7 +26,8 @@ extern void compat_vdso_helper(struct vdso_maps *native, int pipe_fd,
 
 #else /* CONFIG_VDSO */
 
-#define vdso_init()						(0)
+#define vdso_init_dump()					(0)
+#define vdso_init_restore()					(0)
 #define parasite_fixup_vdso(ctl, pid, vma_area_list)		(0)
 
 #endif /* CONFIG_VDSO */

criu/vdso.c

@@ -466,7 +466,22 @@ static int vdso_fill_compat_symtable(struct vdso_maps *native,
 }
 #endif /* CONFIG_COMPAT */
 
-int vdso_init(void)
+int vdso_init_dump(void)
+{
+	if (vdso_parse_maps(PROC_SELF, &vdso_maps)) {
+		pr_err("Failed reading self/maps for filling vdso/vvar bounds\n");
+		return -1;
+	}
+
+	if (kdat.pmap != PM_FULL)
+		pr_info("VDSO detection turned off\n");
+	else if (vaddr_to_pfn(vdso_maps.vdso_start, &vdso_pfn))
+		return -1;
+
+	return 0;
+}
+
+int vdso_init_restore(void)
 {
 	if (vdso_parse_maps(PROC_SELF, &vdso_maps)) {
 		pr_err("Failed reading self/maps for filling vdso/vvar bounds\n");
@@ -483,10 +498,5 @@ int vdso_init(void)
 		return -1;
 	}
 
-	if (kdat.pmap != PM_FULL)
-		pr_info("VDSO detection turned off\n");
-	else if (vaddr_to_pfn(vdso_maps.vdso_start, &vdso_pfn))
-		return -1;
-
 	return 0;
 }