[PATCH v3 01/12] lib/kasan: introduce CONFIG_ARCH_DEFER_KASAN option

[Alexander Gordeev]

On Thu, Jul 17, 2025 at 07:27:21PM +0500, Sabyrzhan Tasbolatov wrote:
> Introduce CONFIG_ARCH_DEFER_KASAN to identify architectures that need
> to defer KASAN initialization until shadow memory is properly set up.
> 
> Some architectures (like PowerPC with radix MMU) need to set up their
> shadow memory mappings before KASAN can be safely enabled, while others
> (like s390, x86, arm) can enable KASAN much earlier or even from the
> beginning.
> 
> This option allows us to:
> 1. Use static keys only where needed (avoiding overhead)
> 2. Use compile-time constants for arch that don't need runtime checks
> 3. Maintain optimal performance for both scenarios
> 
> Architectures that need deferred KASAN should select this option.
> Architectures that can enable KASAN early will get compile-time
> optimizations instead of runtime checks.
> 
> Closes: https://bugzilla.kernel.org/show_bug.cgi?id=217049
> Signed-off-by: Sabyrzhan Tasbolatov <snovitoll at gmail.com>
> ---
> Changes in v3:
> - Introduced CONFIG_ARCH_DEFER_KASAN to control static key usage
> ---
>  lib/Kconfig.kasan | 8 ++++++++
>  1 file changed, 8 insertions(+)

Acked-by: Alexander Gordeev <agordeev at linux.ibm.com> # s390