x86/xen: mark xen_pv_play_dead() as __noreturn

Mark xen_pv_play_dead() and related to that xen_cpu_bringup_again()
as "__noreturn".
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20221125063248.30256-3-jgross@suse.comSigned-off-by: Juergen Gross <jgross@suse.com>

arch/x86/xen/smp.h

@@ -21,7 +21,7 @@ void xen_smp_send_reschedule(int cpu);
 void xen_smp_send_call_function_ipi(const struct cpumask *mask);
 void xen_smp_send_call_function_single_ipi(int cpu);
 
-void xen_cpu_bringup_again(unsigned long stack);
+void __noreturn xen_cpu_bringup_again(unsigned long stack);
 
 struct xen_common_irq {
 	int irq;

arch/x86/xen/smp_pv.c

@@ -381,7 +381,7 @@ static void xen_pv_cpu_die(unsigned int cpu)
 	}
 }
 
-static void xen_pv_play_dead(void) /* used only with HOTPLUG_CPU */
+static void __noreturn xen_pv_play_dead(void) /* used only with HOTPLUG_CPU */
 {
 	play_dead_common();
 	HYPERVISOR_vcpu_op(VCPUOP_down, xen_vcpu_nr(smp_processor_id()), NULL);
@@ -400,7 +400,7 @@ static void xen_pv_cpu_die(unsigned int cpu)
 	BUG();
 }
 
-static void xen_pv_play_dead(void)
+static void __noreturn xen_pv_play_dead(void)
 {
 	BUG();
 }

tools/objtool/check.c

@@ -186,6 +186,7 @@ static bool __dead_end_function(struct objtool_file *file, struct symbol *func,
 		"snp_abort",
 		"stop_this_cpu",
 		"usercopy_abort",
+		"xen_cpu_bringup_again",
 		"xen_start_kernel",
 	};