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Message-ID: <CAMj1kXGf6op6TRcK7w2xQV9aUQzydRd0dfxFmsMDXqpTNB9PbA@mail.gmail.com>
Date: Sun, 1 Jun 2025 11:03:57 +0200
From: Ard Biesheuvel <ardb@...nel.org>
To: Eric Biggers <ebiggers@...nel.org>
Cc: linux-kernel@...r.kernel.org, linux-crypto@...r.kernel.org,
Antoine Tenart <atenart@...nel.org>
Subject: Re: [PATCH] crypto: inside-secure - remove crc32 support
On Sat, 31 May 2025 at 22:43, Eric Biggers <ebiggers@...nel.org> wrote:
>
> From: Eric Biggers <ebiggers@...gle.com>
>
> The crc32 acceleration in the inside-secure driver is accessible only as
> an asynchronous hash. However, there seems to be no corresponding user
> of crc32 in the kernel that supports asynchronous hashes. Therefore,
> this code seems to be unused.
>
> The patch that added this code provided no justification for its
> inclusion. All devicetree bindings for this accelerator are for arm64;
> arm64 CPUs often have CRC or PMULL instructions, which already
> accelerate crc32 very well. And these actually work with the crc32
> users in the kernel, unlike this driver which doesn't.
>
CRC instructions are mandatory in the ARM architecture revision v8.1,
and the only known core that does not implement them is the long
obsolete APM X-Gene.
> Remove this unnecessary code.
>
> Cc: Antoine Tenart <atenart@...nel.org>
> Signed-off-by: Eric Biggers <ebiggers@...gle.com>
Acked-by: Ard Biesheuvel <ardb@...nel.org>
> ---
>
> I'm planning to take this patch via the crc tree.
>
> drivers/crypto/inside-secure/safexcel.c | 1 -
> drivers/crypto/inside-secure/safexcel.h | 1 -
> drivers/crypto/inside-secure/safexcel_hash.c | 92 +-------------------
> 3 files changed, 2 insertions(+), 92 deletions(-)
>
> diff --git a/drivers/crypto/inside-secure/safexcel.c b/drivers/crypto/inside-secure/safexcel.c
> index 9ca80d082c4fb..c3b2b22934b7e 100644
> --- a/drivers/crypto/inside-secure/safexcel.c
> +++ b/drivers/crypto/inside-secure/safexcel.c
> @@ -1216,11 +1216,10 @@ static struct safexcel_alg_template *safexcel_algs[] = {
> &safexcel_alg_authenc_hmac_sha384_ctr_aes,
> &safexcel_alg_authenc_hmac_sha512_ctr_aes,
> &safexcel_alg_xts_aes,
> &safexcel_alg_gcm,
> &safexcel_alg_ccm,
> - &safexcel_alg_crc32,
> &safexcel_alg_cbcmac,
> &safexcel_alg_xcbcmac,
> &safexcel_alg_cmac,
> &safexcel_alg_chacha20,
> &safexcel_alg_chachapoly,
> diff --git a/drivers/crypto/inside-secure/safexcel.h b/drivers/crypto/inside-secure/safexcel.h
> index 0c79ad78d1c0a..0f27367a85fa2 100644
> --- a/drivers/crypto/inside-secure/safexcel.h
> +++ b/drivers/crypto/inside-secure/safexcel.h
> @@ -957,11 +957,10 @@ extern struct safexcel_alg_template safexcel_alg_authenc_hmac_sha256_ctr_aes;
> extern struct safexcel_alg_template safexcel_alg_authenc_hmac_sha384_ctr_aes;
> extern struct safexcel_alg_template safexcel_alg_authenc_hmac_sha512_ctr_aes;
> extern struct safexcel_alg_template safexcel_alg_xts_aes;
> extern struct safexcel_alg_template safexcel_alg_gcm;
> extern struct safexcel_alg_template safexcel_alg_ccm;
> -extern struct safexcel_alg_template safexcel_alg_crc32;
> extern struct safexcel_alg_template safexcel_alg_cbcmac;
> extern struct safexcel_alg_template safexcel_alg_xcbcmac;
> extern struct safexcel_alg_template safexcel_alg_cmac;
> extern struct safexcel_alg_template safexcel_alg_chacha20;
> extern struct safexcel_alg_template safexcel_alg_chachapoly;
> diff --git a/drivers/crypto/inside-secure/safexcel_hash.c b/drivers/crypto/inside-secure/safexcel_hash.c
> index d2b632193bebb..fd34dc8f5707d 100644
> --- a/drivers/crypto/inside-secure/safexcel_hash.c
> +++ b/drivers/crypto/inside-secure/safexcel_hash.c
> @@ -287,18 +287,12 @@ static int safexcel_handle_req_result(struct safexcel_crypto_priv *priv,
>
> *should_complete = false; /* Not done yet */
> return 1;
> }
>
> - if (unlikely(sreq->digest == CONTEXT_CONTROL_DIGEST_XCM &&
> - ctx->alg == CONTEXT_CONTROL_CRYPTO_ALG_CRC32)) {
> - /* Undo final XOR with 0xffffffff ...*/
> - *(__le32 *)areq->result = ~sreq->state[0];
> - } else {
> - memcpy(areq->result, sreq->state,
> - crypto_ahash_digestsize(ahash));
> - }
> + memcpy(areq->result, sreq->state,
> + crypto_ahash_digestsize(ahash));
> }
>
> cache_len = safexcel_queued_len(sreq);
> if (cache_len)
> memcpy(sreq->cache, sreq->cache_next, cache_len);
> @@ -1879,92 +1873,10 @@ struct safexcel_alg_template safexcel_alg_hmac_md5 = {
> },
> },
> },
> };
>
> -static int safexcel_crc32_cra_init(struct crypto_tfm *tfm)
> -{
> - struct safexcel_ahash_ctx *ctx = crypto_tfm_ctx(tfm);
> - int ret = safexcel_ahash_cra_init(tfm);
> -
> - /* Default 'key' is all zeroes */
> - memset(&ctx->base.ipad, 0, sizeof(u32));
> - return ret;
> -}
> -
> -static int safexcel_crc32_init(struct ahash_request *areq)
> -{
> - struct safexcel_ahash_ctx *ctx = crypto_ahash_ctx(crypto_ahash_reqtfm(areq));
> - struct safexcel_ahash_req *req = ahash_request_ctx_dma(areq);
> -
> - memset(req, 0, sizeof(*req));
> -
> - /* Start from loaded key */
> - req->state[0] = cpu_to_le32(~ctx->base.ipad.word[0]);
> - /* Set processed to non-zero to enable invalidation detection */
> - req->len = sizeof(u32);
> - req->processed = sizeof(u32);
> -
> - ctx->alg = CONTEXT_CONTROL_CRYPTO_ALG_CRC32;
> - req->digest = CONTEXT_CONTROL_DIGEST_XCM;
> - req->state_sz = sizeof(u32);
> - req->digest_sz = sizeof(u32);
> - req->block_sz = sizeof(u32);
> -
> - return 0;
> -}
> -
> -static int safexcel_crc32_setkey(struct crypto_ahash *tfm, const u8 *key,
> - unsigned int keylen)
> -{
> - struct safexcel_ahash_ctx *ctx = crypto_tfm_ctx(crypto_ahash_tfm(tfm));
> -
> - if (keylen != sizeof(u32))
> - return -EINVAL;
> -
> - memcpy(&ctx->base.ipad, key, sizeof(u32));
> - return 0;
> -}
> -
> -static int safexcel_crc32_digest(struct ahash_request *areq)
> -{
> - return safexcel_crc32_init(areq) ?: safexcel_ahash_finup(areq);
> -}
> -
> -struct safexcel_alg_template safexcel_alg_crc32 = {
> - .type = SAFEXCEL_ALG_TYPE_AHASH,
> - .algo_mask = 0,
> - .alg.ahash = {
> - .init = safexcel_crc32_init,
> - .update = safexcel_ahash_update,
> - .final = safexcel_ahash_final,
> - .finup = safexcel_ahash_finup,
> - .digest = safexcel_crc32_digest,
> - .setkey = safexcel_crc32_setkey,
> - .export = safexcel_ahash_export,
> - .import = safexcel_ahash_import,
> - .halg = {
> - .digestsize = sizeof(u32),
> - .statesize = sizeof(struct safexcel_ahash_export_state),
> - .base = {
> - .cra_name = "crc32",
> - .cra_driver_name = "safexcel-crc32",
> - .cra_priority = SAFEXCEL_CRA_PRIORITY,
> - .cra_flags = CRYPTO_ALG_OPTIONAL_KEY |
> - CRYPTO_ALG_ASYNC |
> - CRYPTO_ALG_ALLOCATES_MEMORY |
> - CRYPTO_ALG_KERN_DRIVER_ONLY,
> - .cra_blocksize = 1,
> - .cra_ctxsize = sizeof(struct safexcel_ahash_ctx),
> - .cra_init = safexcel_crc32_cra_init,
> - .cra_exit = safexcel_ahash_cra_exit,
> - .cra_module = THIS_MODULE,
> - },
> - },
> - },
> -};
> -
> static int safexcel_cbcmac_init(struct ahash_request *areq)
> {
> struct safexcel_ahash_ctx *ctx = crypto_ahash_ctx(crypto_ahash_reqtfm(areq));
> struct safexcel_ahash_req *req = ahash_request_ctx_dma(areq);
>
>
> base-commit: 4cb6c8af8591135ec000fbe4bb474139ceec595d
> --
> 2.49.0
>
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