objtool: Fix for unreachable instruction warning
On Sat, Jan 28, 2023 at 11:06:34AM -0800, Paul E. McKenney wrote:
> Sorry to be a nag, but I am still seeing this. Not a huge problem because
> I now filter it out so that it does not get in the way of other bugs,
> but I figured that I should follow up.
Does this fix it? (works for me)
If so, I'll need to extend it for all arches.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index 40d156a..5db0dab 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -712,6 +712,7 @@ void arch_cpu_idle_enter(void)
void arch_cpu_idle_dead(void)
{
play_dead();
+ BUG();
}
/*
diff --git a/include/linux/cpu.h b/include/linux/cpu.h
index 314802f..7fbbd15 100644
--- a/include/linux/cpu.h
+++ b/include/linux/cpu.h
@@ -185,7 +185,7 @@ void arch_cpu_idle(void);
void arch_cpu_idle_prepare(void);
void arch_cpu_idle_enter(void);
void arch_cpu_idle_exit(void);
-void arch_cpu_idle_dead(void);
+void __noreturn arch_cpu_idle_dead(void);
int cpu_report_state(int cpu);
int cpu_check_up_prepare(int cpu);
diff --git a/kernel/sched/idle.c b/kernel/sched/idle.c
index f26ab26..921b8b3e 100644
--- a/kernel/sched/idle.c
+++ b/kernel/sched/idle.c
@@ -71,7 +71,7 @@ static noinline int __cpuidle cpu_idle_poll(void)
void __weak arch_cpu_idle_prepare(void) { }
void __weak arch_cpu_idle_enter(void) { }
void __weak arch_cpu_idle_exit(void) { }
-void __weak arch_cpu_idle_dead(void) { }
+void __weak arch_cpu_idle_dead(void) { while (1); }
void __weak arch_cpu_idle(void)
{
cpu_idle_force_poll = 1;
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 4350be7..5a78d5b 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_cpu_idle_dead",
"cpu_bringup_and_idle",
"cpu_startup_entry",
"do_exit",
