restore: Add restoration of the blocked threads signals from the image

To unify the code for both thread leader and regular threads
we move blocked signals for thread leader into threads argument
area and use restore_thread_common() helper.
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

cr-restore.c

@@ -1481,7 +1481,8 @@ static int sigreturn_restore(pid_t pid, CoreEntry *core, struct list_head *tgt_v
 	task_args->t.clear_tid_addr	= core->thread_info->clear_tid_addr;
 	task_args->ids			= *core->ids;
 	task_args->t.gpregs		= *core->thread_info->gpregs;
-	task_args->blk_sigset		= core->tc->blk_sigset;
+	task_args->t.blk_sigset		= core->tc->blk_sigset;
+	task_args->t.has_blk_sigset	= true;
 
 	if (core->thread_core) {
 		task_args->t.has_futex		= true;
@@ -1558,6 +1559,8 @@ static int sigreturn_restore(pid_t pid, CoreEntry *core, struct list_head *tgt_v
 			thread_args[i].has_futex	= true;
 			thread_args[i].futex_rla	= core->thread_core->futex_rla;
 			thread_args[i].futex_rla_len	= core->thread_core->futex_rla_len;
+			thread_args[i].has_blk_sigset	= core->thread_core->has_blk_sigset;
+			thread_args[i].blk_sigset	= core->thread_core->blk_sigset;
 
 			ret = prep_sched_info(&thread_args[i].sp, core->thread_core);
 			if (ret)

include/restorer.h

@@ -76,6 +76,9 @@ struct thread_restore_args {
 	u64				futex_rla;
 	u32				futex_rla_len;
 
+	bool				has_blk_sigset;
+	u64				blk_sigset;
+
 	struct rst_sched_param		sp;
 
 	struct task_restore_core_args	*ta;
@@ -112,7 +115,6 @@ struct task_restore_core_args {
 	MmEntry				mm;
 	u64				mm_saved_auxv[AT_VECTOR_SIZE];
 	u32				mm_saved_auxv_size;
-	u64				blk_sigset;
 	char				comm[TASK_COMM_LEN];
 	TaskKobjIdsEntry		ids;
 

restorer.c

@@ -199,6 +199,9 @@ static int restore_thread_common(struct rt_sigframe *sigframe,
 		}
 	}
 
+	if (args->has_blk_sigset)
+		sigframe->uc.uc_sigmask.sig[0] = args->blk_sigset;
+
 	restore_sched_info(&args->sp);
 
 	return restore_gpregs(sigframe, &args->gpregs);
@@ -497,11 +500,6 @@ long __export_restore_task(struct task_restore_core_args *args)
 	if (restore_thread_common(rt_sigframe, &args->t))
 		goto core_restore_end;
 
-	/*
-	 * Blocked signals.
-	 */
-	rt_sigframe->uc.uc_sigmask.sig[0] = args->blk_sigset;
-
 	/*
 	 * Threads restoration. This requires some more comments. This
 	 * restorer routine and thread restorer routine has the following