On Wed, Mar 17 2021 at 11:12, Andy Lutomirski wrote:
> +
> +#define DEBUG_ENTRY_WARN_ONCE(condition, format...) do {} while (0)
So we have a stub for !DEBUG
> +static __always_inline void kentry_cpu_depth_add(unsigned int n) {}
> +static void kentry_cpu_depth_check(unsigned int n) {}
> +static __always_inline void kentry_cpu_depth_sub(unsigned int n) {}
> +
> +#endif
> +
> /* See comment for enter_from_user_mode() in entry-common.h */
> static __always_inline void __enter_from_user_mode(struct pt_regs *regs)
> {
> + kentry_cpu_depth_add(1);
> arch_check_user_regs(regs);
> lockdep_hardirqs_off(CALLER_ADDR0);
>
> @@ -22,6 +78,14 @@ static __always_inline void __enter_from_user_mode(struct
> pt_regs *regs)
>
> instrumentation_begin();
> trace_hardirqs_off_finish();
> +
> +#ifdef CONFIG_DEBUG_ENTRY
Why do we need that #ifdeffery all over the place?
> + DEBUG_ENTRY_WARN_ONCE(
> + this_cpu_read(kentry_cpu_depth) != 1,
> + "kentry: __enter_from_user_mode() called while kentry thought
> the CPU was in the kernel (%u)",
> + this_cpu_read(kentry_cpu_depth));
Thanks,
tglx
