restorer: Compact rst stack evaluation code

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

cr-restore.c

@@ -2538,11 +2538,7 @@ static int sigreturn_restore(pid_t pid, CoreEntry *core)
 	task_args->vdso_rt_parked_at = (unsigned long)mem + vdso_rt_delta;
 	task_args->vdso_sym_rt = vdso_sym_rt;
 
-	/*
-	 * Adjust stack.
-	 */
-	new_sp = RESTORE_ALIGN_STACK((long)task_args->t->mem_zone.stack,
-			sizeof(task_args->t->mem_zone.stack));
+	new_sp = restorer_stack(task_args->t);
 
 	/* No longer need it */
 	core_entry__free_unpacked(core, NULL);

include/restorer.h

@@ -43,9 +43,6 @@ typedef long (*thread_restore_fcall_t) (struct thread_restore_args *args);
 #define RESTORE_STACK_SIGFRAME		ALIGN(sizeof(struct rt_sigframe) + SIGFRAME_OFFSET, 64)
 #define RESTORE_STACK_SIZE		(KILO(32))
 
-#define RESTORE_ALIGN_STACK(start, size)	\
-	(ALIGN((start) + (size) - sizeof(long), sizeof(long)))
-
 struct restore_mem_zone {
 	u8				redzone[RESTORE_STACK_REDZONE];
 	u8				stack[RESTORE_STACK_SIZE];
@@ -154,6 +151,14 @@ struct task_restore_core_args {
 
 #define SHMEMS_SIZE	4096
 
+#define RESTORE_ALIGN_STACK(start, size)	\
+	(ALIGN((start) + (size) - sizeof(long), sizeof(long)))
+
+static inline unsigned long restorer_stack(struct thread_restore_args *a)
+{
+	return RESTORE_ALIGN_STACK((long)a->mem_zone.stack, RESTORE_STACK_SIZE);
+}
+
 /*
  * pid is a pid of a creater
  * start, end are used for open mapping

pie/restorer.c

@@ -824,10 +824,7 @@ long __export_restore_task(struct task_restore_core_args *args)
 			if (thread_args[i].pid == args->t->pid)
 				continue;
 
-			new_sp =
-				RESTORE_ALIGN_STACK((long)thread_args[i].mem_zone.stack,
-						    sizeof(thread_args[i].mem_zone.stack));
-
+			new_sp = restorer_stack(thread_args + i);
 			last_pid_len = vprint_num(last_pid_buf, sizeof(last_pid_buf), thread_args[i].pid - 1, &s);
 			ret = sys_write(fd, s, last_pid_len);
 			if (ret < 0) {