On Thu, Jan 24, 2019 at 07:27:12PM +0100, Ard Biesheuvel wrote:
> The SIMD routine ported from x86 used to have a special code path
> for inputs < 16 bytes, which got lost somewhere along the way.
> Instead, the current glue code aligns the input pointer to permit
> the NEON routine to use special versions of the vld1 instructions
> that assume 16 byte alignment, but this could result in inputs of
> less than 16 bytes to be passed in.
This description doesn't quite match the patch since the arm64 version of the
assembly doesn't use any alignment specifiers. I take it that actually means
the alignment in the glue code wasn't necessary in the first place?
> This not only fails the new
> extended tests that Eric has implemented, it also results in the
> code reading before the input pointer, which could potentially
> result in crashes when dealing with less than 16 bytes of input
> at the start of a page which is preceded by an unmapped page.
>
> So update the glue code to only invoke the NEON routine if the
> input is more than 16 bytes.
>
> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
Can you add:
Fixes: 6ef5737f3931 ("crypto: arm64/crct10dif - port x86 SSE implementation to arm64")
Cc: stable@xxxxxxxxxxxxxxx
> ---
> arch/arm64/crypto/crct10dif-ce-glue.c | 25 +++++---------------
> 1 file changed, 6 insertions(+), 19 deletions(-)
>
> diff --git a/arch/arm64/crypto/crct10dif-ce-glue.c b/arch/arm64/crypto/crct10dif-ce-glue.c
> index b461d62023f2..567c24f3d224 100644
> --- a/arch/arm64/crypto/crct10dif-ce-glue.c
> +++ b/arch/arm64/crypto/crct10dif-ce-glue.c
> @@ -39,26 +39,13 @@ static int crct10dif_update(struct shash_desc *desc, const u8 *data,
> unsigned int length)
> {
> u16 *crc = shash_desc_ctx(desc);
> - unsigned int l;
>
> - if (unlikely((u64)data % CRC_T10DIF_PMULL_CHUNK_SIZE)) {
> - l = min_t(u32, length, CRC_T10DIF_PMULL_CHUNK_SIZE -
> - ((u64)data % CRC_T10DIF_PMULL_CHUNK_SIZE));
> -
> - *crc = crc_t10dif_generic(*crc, data, l);
> -
> - length -= l;
> - data += l;
> - }
> -
> - if (length > 0) {
> - if (may_use_simd()) {
> - kernel_neon_begin();
> - *crc = crc_t10dif_pmull(*crc, data, length);
> - kernel_neon_end();
> - } else {
> - *crc = crc_t10dif_generic(*crc, data, length);
> - }
> + if (length >= CRC_T10DIF_PMULL_CHUNK_SIZE && may_use_simd()) {
> + kernel_neon_begin();
> + *crc = crc_t10dif_pmull(*crc, data, length);
> + kernel_neon_end();
> + } else {
> + *crc = crc_t10dif_generic(*crc, data, length);
> }
>
> return 0;
> --
> 2.17.1
>
