On Thu, 31 Mar 2022 20:59:49 +0800 kernel test robot <lkp@xxxxxxxxx> wrote: > >> arch/arm64/kernel/stacktrace.c:289:13: error: implicit declaration of function 'task_scs' is invalid in C99 [-Werror,-Wimplicit-function-declaration] > scs_base = task_scs(current); > ^ Thanks. Presumably this: --- a/arch/arm64/kernel/stacktrace.c~arm64-implement-stack_trace_save_shadow-fix +++ a/arch/arm64/kernel/stacktrace.c @@ -213,6 +213,7 @@ noinline notrace void arch_stack_walk(st walk_stackframe(task, &frame, consume_entry, cookie); } +#ifdef CONFIG_SHADOW_CALL_STACK static const struct { unsigned long ** __percpu saved; unsigned long ** __percpu base; @@ -293,3 +294,4 @@ out: preempt_enable(); return len; } +#endif /* CONFIG_SHADOW_CALL_STACK */ _