Re: [PATCH v4 11/11] s390/percpu: Rework to simplify percpu_entry() and percpu_exit()

[sashiko-bot@kernel.org]

> The percpu code section functionality uses a rather complex method to
> figure out if the register, which contains the address of the current
> cpu's percpu variable, needs to be adjusted.
> 
> If an interrupt happens within a percpu code section (indicated by a
> lowcore field), the instruction at the interrupted location is
> checked. If it is not a specific AG instruction, the register needs to
> be updated. This mechanism needs to take kprobes into account, and
> enforces a specific instruction ordering.
> 
> Mark Rutland provided a different solution for arm64 [1] which comes
> without such limitations, but requires to use one more instruction, and
> two more registers. Given that this simplifies percpu_entry() and
> percpu_exit() it seems to be worth to go that route.
> 
> [ ... ]
> gcc code generation.
> 
> [1] https://lore.kernel.org/all/20260908151741.394589-1-mark.rutland@arm.com/
> 
> Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

Sashiko has reviewed this patch and found no issues. It looks great!

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Sashiko AI review · https://sashiko.dev/#/patchset/20260921155806.2447506-1-hca@linux.ibm.com?part=11