aes_encrypt() now uses AES instructions when available instead of always
using table-based code. AES instructions are constant-time and don't
benefit from disabling IRQs as a constant-time hardening measure.
In fact, on two architectures (arm and riscv) disabling IRQs is
counterproductive because it prevents the AES instructions from being
used. (See the may_use_simd() implementation on those architectures.)
Therefore, let's remove the IRQ disabling/enabling and leave the choice
of constant-time hardening measures to the AES library code.
Note that currently the arm table-based AES code (which runs on arm
kernels that don't have ARMv8 CE) disables IRQs, while the generic
table-based AES code does not. So this does technically regress in
constant-time hardening when that generic code is used. But as
discussed in commit a22fd0e3c4 ("lib/crypto: aes: Introduce improved
AES library") I think just leaving IRQs enabled is the right choice.
Disabling them is slow and can cause problems, and AES instructions
(which modern CPUs have) solve the problem in a much better way anyway.
Link: https://lore.kernel.org/r/20260331024430.51755-1-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
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