[PATCH 28/31] kasan: add kasan.vmalloc command line flag

[Marco Elver]

On Tue, Nov 30, 2021 at 11:08PM +0100, andrey.konovalov at linux.dev wrote:
[...]
>  enum kasan_arg_stacktrace {
>  	KASAN_ARG_STACKTRACE_DEFAULT,
>  	KASAN_ARG_STACKTRACE_OFF,
> @@ -40,6 +46,7 @@ enum kasan_arg_stacktrace {
>  
>  static enum kasan_arg kasan_arg __ro_after_init;
>  static enum kasan_arg_mode kasan_arg_mode __ro_after_init;
> +static enum kasan_arg_vmalloc kasan_arg_vmalloc __ro_after_init;
>  static enum kasan_arg_stacktrace kasan_arg_stacktrace __ro_after_init;

It just occurred to me that all of these (except kasan_arg_mode) are
only used by __init functions, so they could actually be marked
__initdata instead of __ro_after_init to free up some bytes after init.

Not sure if you think it's worth it, I leave it to you.

[...] 
> +	switch (kasan_arg_vmalloc) {
> +	case KASAN_ARG_VMALLOC_DEFAULT:
> +		/* Default to enabling vmalloc tagging. */
> +		static_branch_enable(&kasan_flag_vmalloc);
> +		break;
> +	case KASAN_ARG_VMALLOC_OFF:
> +		/* Do nothing, kasan_flag_vmalloc keeps its default value. */
> +		break;
> +	case KASAN_ARG_VMALLOC_ON:
> +		static_branch_enable(&kasan_flag_vmalloc);
> +		break;
> +	}

The KASAN_ARG_STACKTRACE_DEFAULT and KASAN_ARG_VMALLOC_ON cases can be
combined.