crypto: Clean up arm64 AES-CCM code

From: Ard Biesheuvel <[email protected]>

The AES-CCM driver was written 10+ years ago, based on the very first kernel mode NEON API for arm64, which eagerly preserved/restored the NEON registers on each call to kernel_neon_begin() resp. kernel_neon_end().

For this reason, the asm helpers were constructed in a way that used only 6 NEON registers, as the kernel mode NEON API at the time implemented an optimization where kernel_neon_begin() took an int denoting the number of NEON registers to preserve/restore. Given that no actual hardware existed at the time (except perhaps for APM Xgene1 which did not implement the crypto instructions), all of this was based on premature assumptions.

These days, the NEON API is a bit more sophisticated, and does not bother to preserve/restore anything unless it is needed (e.g., when context switching or returning to user space). It also no longer disables preemption. Finally, we've developed some code patterns in the mean time to deal with tail blocks more cleanly and efficiently.

So let's bring the CCM driver up to date with all of this.

Changes since v1:
- keep primary en/decryption paths separate
- fix rebase error in v1

Ard Biesheuvel (8):
crypto: arm64/aes-ccm - Revert "Rewrite skcipher walker loop"
crypto: arm64/aes-ccm - Keep NEON enabled during skcipher walk
crypto: arm64/aes-ccm - Pass short inputs via stack buffer
crypto: arm64/aes-ccm - Replace bytewise tail handling with NEON
permute
crypto: arm64/aes-ccm - Reuse existing MAC update for AAD input
crypto: arm64/aes-ccm - Cache round keys and unroll AES loops
crypto: arm64/aes-ccm - Merge encrypt and decrypt tail handling
crypto: arm64/aes-ccm - Merge finalization into en/decrypt asm helpers

 arch/arm64/crypto/Kconfig           |   1 +
 arch/arm64/crypto/aes-ce-ccm-core.S | 265 +++++++-------------
 arch/arm64/crypto/aes-ce-ccm-glue.c | 154 ++++++++----
 arch/arm64/crypto/aes-glue.c        |   1 +
 4 files changed, 200 insertions(+), 221 deletions(-)

2.43.0.381.gb435a96ce8-goog