init: Mark start_kernel() __noreturn

Now that arch_call_rest_init() is __noreturn, mark its caller
start_kernel() __noreturn.

Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/7069acf026a195f26a88061227fba5a3b0337b9a.1681342859.git.jpoimboe@kernel.org

Author: jpoimboe

include/linux/start_kernel.h

@@ -8,7 +8,7 @@
 /* Define the prototype for start_kernel here, rather than cluttering
    up something else. */
 
-extern asmlinkage void __init start_kernel(void);
+extern asmlinkage void __init __noreturn start_kernel(void);
 extern void __init __noreturn arch_call_rest_init(void);
 extern void __ref __noreturn rest_init(void);
 

init/main.c

@@ -937,7 +937,7 @@ static void __init print_unknown_bootoptions(void)
 	memblock_free(unknown_options, len);
 }
 
-asmlinkage __visible void __init __no_sanitize_address start_kernel(void)
+asmlinkage __visible void __init __no_sanitize_address __noreturn start_kernel(void)
 {
 	char *command_line;
 	char *after_dashes;

tools/objtool/check.c

@@ -222,6 +222,7 @@ static bool __dead_end_function(struct objtool_file *file, struct symbol *func,
 		"rewind_stack_and_make_dead",
 		"sev_es_terminate",
 		"snp_abort",
+		"start_kernel",
 		"stop_this_cpu",
 		"usercopy_abort",
 		"xen_cpu_bringup_again",