Re: [PATCH] debug: Do not permit CONFIG_DEBUG_STACK_USAGE=y on IA64 or PARISC

[Ingo Molnar <mingo@kernel.org>]

* Tony Luck <tony.luck@intel.com> wrote:

> The stack_not_used() function in <linux/sched.h> assumes that stacks
> grow downwards. This is not true on IA64 or PARISC, so this function
> would walk off in the wrong direction and into the weeds.
> 
> Found on IA64 because of a compilation failure with recursive dependencies
> on IA64_TASKSIZE and IA64_THREAD_INFO_SIZE.
> 
> Fixing the code is possible, but should be combined with other
> infrastructure additions to set up the "canary" at the end of the stack.
> 
> Reported-by: Fengguang Wu <fengguang.wu@intel.com> (failed allmodconfig build)
> Signed-off-by: Tony Luck <tony.luck@intel.com>
> ---
>  lib/Kconfig.debug | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
> index ff5bdee..4a18650 100644
> --- a/lib/Kconfig.debug
> +++ b/lib/Kconfig.debug
> @@ -714,7 +714,7 @@ config STACKTRACE
>  
>  config DEBUG_STACK_USAGE
>  	bool "Stack utilization instrumentation"
> -	depends on DEBUG_KERNEL
> +	depends on DEBUG_KERNEL && !IA64 && !PARISC

The modern way of doing this is by adding an ARCH_SUPPORTS_ 
flag.

Thanks,

	Ingo