[PATCH v2 23/24] init: Make arch_call_rest_init() and rest_init() __noreturn

Josh Poimboeuf
2023-02-14T07:10:05Z

arch_call_rest_init() and rest_init() don't return. Annotate them as
such.

Fixes the following warning:

init/main.o: warning: objtool: start_kernel+0x4ad: unreachable instruction

Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
arch/s390/kernel/setup.c | 2 +-
include/linux/start_kernel.h | 4 ++--
init/main.c | 4 ++--
tools/objtool/check.c | 2 ++
4 files changed, 7 insertions(+), 5 deletions(-)

diff --git a/arch/s390/kernel/setup.c b/arch/s390/kernel/setup.c
index 696c9e007a36..85abff362f29 100644
--- a/arch/s390/kernel/setup.c
+++ b/arch/s390/kernel/setup.c
@@ -393,7 +393,7 @@ int __init arch_early_irq_init(void)
return 0;
}

-void __init arch_call_rest_init(void)
+void __init __noreturn arch_call_rest_init(void)
{
unsigned long stack;

diff --git a/include/linux/start_kernel.h b/include/linux/start_kernel.h
index 8b369a41c03c..864921e54c92 100644
--- a/include/linux/start_kernel.h
+++ b/include/linux/start_kernel.h
@@ -9,7 +9,7 @@
up something else. */

extern asmlinkage void __init start_kernel(void);
-extern void __init arch_call_rest_init(void);
-extern void __ref rest_init(void);
+extern void __init __noreturn arch_call_rest_init(void);
+extern void __ref __noreturn rest_init(void);

#endif /* _LINUX_START_KERNEL_H */
diff --git a/init/main.c b/init/main.c
index e1c3911d7c70..ef71a9902e47 100644
--- a/init/main.c
+++ b/init/main.c
@@ -683,7 +683,7 @@ static void __init setup_command_line(char *command_line)

static __initdata DECLARE_COMPLETION(kthreadd_done);

-noinline void __ref rest_init(void)
+noinline void __ref __noreturn rest_init(void)
{
struct task_struct *tsk;
int pid;
@@ -889,7 +889,7 @@ static int __init early_randomize_kstack_offset(char *buf)
early_param("randomize_kstack_offset", early_randomize_kstack_offset);
#endif

-void __init __weak arch_call_rest_init(void)
+void __init __weak __noreturn arch_call_rest_init(void)
{
rest_init();
}
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 0a1cf867d9b2..f79baae3e338 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -167,6 +167,7 @@ static bool __dead_end_function(struct objtool_file *file, struct symbol *func,
"__reiserfs_panic",
"__stack_chk_fail",
"__ubsan_handle_builtin_unreachable",
+ "arch_call_rest_init",
"cpu_bringup_and_idle",
"cpu_startup_entry",
"do_exit",
@@ -181,6 +182,7 @@ static bool __dead_end_function(struct objtool_file *file, struct symbol *func,
"machine_real_restart",
"make_task_dead",
"panic",
+ "rest_init",
"rewind_stack_and_make_dead",
"sev_es_terminate",
"snp_abort",
--
2.39.1