Re: [PATCH 2/4] arm64: atomics: lse: Silence intentional wrapping addition

[Will Deacon]

On Wed, Apr 24, 2024 at 12:17:35PM -0700, Kees Cook wrote:
> Annotate atomic_add_return() and atomic_sub_return() to avoid signed
> overflow instrumentation. They are expected to wrap around.
> 
> Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
> ---
> Cc: Will Deacon <will@xxxxxxxxxx>
> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> Cc: Boqun Feng <boqun.feng@xxxxxxxxx>
> Cc: Mark Rutland <mark.rutland@xxxxxxx>
> Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
> Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
> ---
>  arch/arm64/include/asm/atomic_lse.h | 10 ++++++----
>  1 file changed, 6 insertions(+), 4 deletions(-)

How come the ll/sc routines (in atomic_ll_sc.h) don't need the same
treatment? If that's just an oversight, then maybe it's better to
instrument the higher-level wrappers in asm/atomic.h?

Will