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Subject: Re: [PATCH] crypto: sa2ul - Reduce stack usage
To:     Herbert Xu <herbert@gondor.apana.org.au>,
        kernel test robot <lkp@intel.com>
CC:     Keerthy <j-keerthy@ti.com>, <kbuild-all@lists.01.org>,
        <linux-kernel@vger.kernel.org>
References: <202008161440.gqdm1lpp%lkp@intel.com>
 <20200824131230.GA4813@gondor.apana.org.au>
From:   Tero Kristo <t-kristo@ti.com>
Message-ID: <e4707f14-c395-7f08-6ee2-1635427a4d07@ti.com>
Date:   Tue, 25 Aug 2020 16:14:53 +0300
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On 24/08/2020 16:12, Herbert Xu wrote:
> On Sun, Aug 16, 2020 at 02:56:43PM +0800, kernel test robot wrote:
>>
>>     drivers/crypto/sa2ul.c: In function 'sa_prepare_iopads':
>>>> drivers/crypto/sa2ul.c:432:1: warning: the frame size of 1076 bytes is larger than 1024 bytes [-Wframe-larger-than=]
> 
> This patch tries to reduce the stack frame size in sa2ul.
> 
> ---8<---
> This patch reduces the stack usage in sa2ul:
> 
> 1. Move the exported sha state into sa_prepare_iopads so that it
> can occupy the same space as the k_pad buffer.
> 
> 2. Use one buffer for ipad/opad in sa_prepare_iopads.
> 
> 3. Remove ipad/opad buffer from sa_set_sc_auth.
> 
> 4. Use async skcipher fallback and remove on-stack request from
> sa_cipher_run.
> 
> Reported-by: kernel test robot <lkp@intel.com>
> Fixes: d2c8ac187fc9 ("crypto: sa2ul - Add AEAD algorithm support")
> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

This patch seems ok, I also tested it locally so:

Reviewed-by: Tero Kristo <t-kristo@ti.com>
Tested-by: Tero Kristo <t-kristo@ti.com>

> 
> diff --git a/drivers/crypto/sa2ul.c b/drivers/crypto/sa2ul.c
> index 5bc099052bd2..66629cad9531 100644
> --- a/drivers/crypto/sa2ul.c
> +++ b/drivers/crypto/sa2ul.c
> @@ -9,8 +9,10 @@
>    *		Tero Kristo
>    */
>   #include <linux/clk.h>
> +#include <linux/dma-mapping.h>
>   #include <linux/dmaengine.h>
>   #include <linux/dmapool.h>
> +#include <linux/kernel.h>
>   #include <linux/module.h>
>   #include <linux/of_device.h>
>   #include <linux/platform_device.h>
> @@ -356,42 +358,45 @@ static void sa_swiz_128(u8 *in, u16 len)
>   }
>   
>   /* Prepare the ipad and opad from key as per SHA algorithm step 1*/
> -static void prepare_kiopad(u8 *k_ipad, u8 *k_opad, const u8 *key, u16 key_sz)
> +static void prepare_kipad(u8 *k_ipad, const u8 *key, u16 key_sz)
>   {
>   	int i;
>   
> -	for (i = 0; i < key_sz; i++) {
> +	for (i = 0; i < key_sz; i++)
>   		k_ipad[i] = key[i] ^ 0x36;
> -		k_opad[i] = key[i] ^ 0x5c;
> -	}
>   
>   	/* Instead of XOR with 0 */
> -	for (; i < SHA1_BLOCK_SIZE; i++) {
> +	for (; i < SHA1_BLOCK_SIZE; i++)
>   		k_ipad[i] = 0x36;
> +}
> +
> +static void prepare_kopad(u8 *k_opad, const u8 *key, u16 key_sz)
> +{
> +	int i;
> +
> +	for (i = 0; i < key_sz; i++)
> +		k_opad[i] = key[i] ^ 0x5c;
> +
> +	/* Instead of XOR with 0 */
> +	for (; i < SHA1_BLOCK_SIZE; i++)
>   		k_opad[i] = 0x5c;
> -	}
>   }
>   
> -static void sa_export_shash(struct shash_desc *hash, int block_size,
> +static void sa_export_shash(void *state, struct shash_desc *hash,
>   			    int digest_size, __be32 *out)
>   {
> -	union {
> -		struct sha1_state sha1;
> -		struct sha256_state sha256;
> -		struct sha512_state sha512;
> -	} sha;
> -	void *state;
> +	struct sha1_state *sha1;
> +	struct sha256_state *sha256;
>   	u32 *result;
> -	int i;
>   
>   	switch (digest_size) {
>   	case SHA1_DIGEST_SIZE:
> -		state = &sha.sha1;
> -		result = sha.sha1.state;
> +		sha1 = state;
> +		result = sha1->state;
>   		break;
>   	case SHA256_DIGEST_SIZE:
> -		state = &sha.sha256;
> -		result = sha.sha256.state;
> +		sha256 = state;
> +		result = sha256->state;
>   		break;
>   	default:
>   		dev_err(sa_k3_dev, "%s: bad digest_size=%d\n", __func__,
> @@ -401,8 +406,7 @@ static void sa_export_shash(struct shash_desc *hash, int block_size,
>   
>   	crypto_shash_export(hash, state);
>   
> -	for (i = 0; i < digest_size >> 2; i++)
> -		out[i] = cpu_to_be32(result[i]);
> +	cpu_to_be32_array(out, result, digest_size / 4);
>   }
>   
>   static void sa_prepare_iopads(struct algo_data *data, const u8 *key,
> @@ -411,24 +415,28 @@ static void sa_prepare_iopads(struct algo_data *data, const u8 *key,
>   	SHASH_DESC_ON_STACK(shash, data->ctx->shash);
>   	int block_size = crypto_shash_blocksize(data->ctx->shash);
>   	int digest_size = crypto_shash_digestsize(data->ctx->shash);
> -	u8 k_ipad[SHA1_BLOCK_SIZE];
> -	u8 k_opad[SHA1_BLOCK_SIZE];
> +	union {
> +		struct sha1_state sha1;
> +		struct sha256_state sha256;
> +		u8 k_pad[SHA1_BLOCK_SIZE];
> +	} sha;
>   
>   	shash->tfm = data->ctx->shash;
>   
> -	prepare_kiopad(k_ipad, k_opad, key, key_sz);
> -
> -	memzero_explicit(ipad, block_size);
> -	memzero_explicit(opad, block_size);
> +	prepare_kipad(sha.k_pad, key, key_sz);
>   
>   	crypto_shash_init(shash);
> -	crypto_shash_update(shash, k_ipad, block_size);
> -	sa_export_shash(shash, block_size, digest_size, ipad);
> +	crypto_shash_update(shash, sha.k_pad, block_size);
> +	sa_export_shash(&sha, shash, digest_size, ipad);
> +
> +	prepare_kopad(sha.k_pad, key, key_sz);
>   
>   	crypto_shash_init(shash);
> -	crypto_shash_update(shash, k_opad, block_size);
> +	crypto_shash_update(shash, sha.k_pad, block_size);
>   
> -	sa_export_shash(shash, block_size, digest_size, opad);
> +	sa_export_shash(&sha, shash, digest_size, opad);
> +
> +	memzero_explicit(&sha, sizeof(sha));
>   }
>   
>   /* Derive the inverse key used in AES-CBC decryption operation */
> @@ -501,7 +509,8 @@ static int sa_set_sc_enc(struct algo_data *ad, const u8 *key, u16 key_sz,
>   static void sa_set_sc_auth(struct algo_data *ad, const u8 *key, u16 key_sz,
>   			   u8 *sc_buf)
>   {
> -	__be32 ipad[64], opad[64];
> +	__be32 *ipad = (void *)(sc_buf + 32);
> +	__be32 *opad = (void *)(sc_buf + 64);
>   
>   	/* Set Authentication mode selector to hash processing */
>   	sc_buf[0] = SA_HASH_PROCESSING;
> @@ -510,14 +519,9 @@ static void sa_set_sc_auth(struct algo_data *ad, const u8 *key, u16 key_sz,
>   	sc_buf[1] |= ad->auth_ctrl;
>   
>   	/* Copy the keys or ipad/opad */
> -	if (ad->keyed_mac) {
> +	if (ad->keyed_mac)
>   		ad->prep_iopad(ad, key, key_sz, ipad, opad);
> -
> -		/* Copy ipad to AuthKey */
> -		memcpy(&sc_buf[32], ipad, ad->hash_size);
> -		/* Copy opad to Aux-1 */
> -		memcpy(&sc_buf[64], opad, ad->hash_size);
> -	} else {
> +	else {
>   		/* basic hash */
>   		sc_buf[1] |= SA_BASIC_HASH;
>   	}
> @@ -814,7 +818,7 @@ static void sa_cipher_cra_exit(struct crypto_skcipher *tfm)
>   	sa_free_ctx_info(&ctx->enc, data);
>   	sa_free_ctx_info(&ctx->dec, data);
>   
> -	crypto_free_sync_skcipher(ctx->fallback.skcipher);
> +	crypto_free_skcipher(ctx->fallback.skcipher);
>   }
>   
>   static int sa_cipher_cra_init(struct crypto_skcipher *tfm)
> @@ -822,6 +826,7 @@ static int sa_cipher_cra_init(struct crypto_skcipher *tfm)
>   	struct sa_tfm_ctx *ctx = crypto_skcipher_ctx(tfm);
>   	struct sa_crypto_data *data = dev_get_drvdata(sa_k3_dev);
>   	const char *name = crypto_tfm_alg_name(&tfm->base);
> +	struct crypto_skcipher *child;
>   	int ret;
>   
>   	memzero_explicit(ctx, sizeof(*ctx));
> @@ -836,14 +841,17 @@ static int sa_cipher_cra_init(struct crypto_skcipher *tfm)
>   		return ret;
>   	}
>   
> -	ctx->fallback.skcipher =
> -		crypto_alloc_sync_skcipher(name, 0, CRYPTO_ALG_NEED_FALLBACK);
> +	child = crypto_alloc_skcipher(name, 0, CRYPTO_ALG_NEED_FALLBACK);
>   
> -	if (IS_ERR(ctx->fallback.skcipher)) {
> +	if (IS_ERR(child)) {
>   		dev_err(sa_k3_dev, "Error allocating fallback algo %s\n", name);
> -		return PTR_ERR(ctx->fallback.skcipher);
> +		return PTR_ERR(child);
>   	}
>   
> +	ctx->fallback.skcipher = child;
> +	crypto_skcipher_set_reqsize(tfm, crypto_skcipher_reqsize(child) +
> +					 sizeof(struct skcipher_request));
> +
>   	dev_dbg(sa_k3_dev, "%s(0x%p) sc-ids(0x%x(0x%pad), 0x%x(0x%pad))\n",
>   		__func__, tfm, ctx->enc.sc_id, &ctx->enc.sc_phys,
>   		ctx->dec.sc_id, &ctx->dec.sc_phys);
> @@ -854,6 +862,7 @@ static int sa_cipher_setkey(struct crypto_skcipher *tfm, const u8 *key,
>   			    unsigned int keylen, struct algo_data *ad)
>   {
>   	struct sa_tfm_ctx *ctx = crypto_skcipher_ctx(tfm);
> +	struct crypto_skcipher *child = ctx->fallback.skcipher;
>   	int cmdl_len;
>   	struct sa_cmdl_cfg cfg;
>   	int ret;
> @@ -869,12 +878,10 @@ static int sa_cipher_setkey(struct crypto_skcipher *tfm, const u8 *key,
>   	cfg.enc_eng_id = ad->enc_eng.eng_id;
>   	cfg.iv_size = crypto_skcipher_ivsize(tfm);
>   
> -	crypto_sync_skcipher_clear_flags(ctx->fallback.skcipher,
> +	crypto_skcipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
> +	crypto_skcipher_set_flags(child, tfm->base.crt_flags &
>   					 CRYPTO_TFM_REQ_MASK);
> -	crypto_sync_skcipher_set_flags(ctx->fallback.skcipher,
> -				       tfm->base.crt_flags &
> -				       CRYPTO_TFM_REQ_MASK);
> -	ret = crypto_sync_skcipher_setkey(ctx->fallback.skcipher, key, keylen);
> +	ret = crypto_skcipher_setkey(child, key, keylen);
>   	if (ret)
>   		return ret;
>   
> @@ -1234,7 +1241,6 @@ static int sa_cipher_run(struct skcipher_request *req, u8 *iv, int enc)
>   	    crypto_skcipher_ctx(crypto_skcipher_reqtfm(req));
>   	struct crypto_alg *alg = req->base.tfm->__crt_alg;
>   	struct sa_req sa_req = { 0 };
> -	int ret;
>   
>   	if (!req->cryptlen)
>   		return 0;
> @@ -1246,20 +1252,18 @@ static int sa_cipher_run(struct skcipher_request *req, u8 *iv, int enc)
>   	if (req->cryptlen > SA_MAX_DATA_SZ ||
>   	    (req->cryptlen >= SA_UNSAFE_DATA_SZ_MIN &&
>   	     req->cryptlen <= SA_UNSAFE_DATA_SZ_MAX)) {
> -		SYNC_SKCIPHER_REQUEST_ON_STACK(subreq, ctx->fallback.skcipher);
> +		struct skcipher_request *subreq = skcipher_request_ctx(req);
>   
> -		skcipher_request_set_sync_tfm(subreq, ctx->fallback.skcipher);
> +		skcipher_request_set_tfm(subreq, ctx->fallback.skcipher);
>   		skcipher_request_set_callback(subreq, req->base.flags,
> -					      NULL, NULL);
> +					      req->base.complete,
> +					      req->base.data);
>   		skcipher_request_set_crypt(subreq, req->src, req->dst,
>   					   req->cryptlen, req->iv);
>   		if (enc)
> -			ret = crypto_skcipher_encrypt(subreq);
> +			return crypto_skcipher_encrypt(subreq);
>   		else
> -			ret = crypto_skcipher_decrypt(subreq);
> -
> -		skcipher_request_zero(subreq);
> -		return ret;
> +			return crypto_skcipher_decrypt(subreq);
>   	}
>   
>   	sa_req.size = req->cryptlen;
> diff --git a/drivers/crypto/sa2ul.h b/drivers/crypto/sa2ul.h
> index 7f7e3fe60d11..bb40df3876e5 100644
> --- a/drivers/crypto/sa2ul.h
> +++ b/drivers/crypto/sa2ul.h
> @@ -12,10 +12,8 @@
>   #ifndef _K3_SA2UL_
>   #define _K3_SA2UL_
>   
> -#include <linux/interrupt.h>
> -#include <linux/skbuff.h>
> -#include <linux/hw_random.h>
>   #include <crypto/aes.h>
> +#include <crypto/sha.h>
>   
>   #define SA_ENGINE_ENABLE_CONTROL	0x1000
>   
> @@ -311,7 +309,7 @@ struct sa_tfm_ctx {
>   	struct crypto_shash	*shash;
>   	/* for fallback */
>   	union {
> -		struct crypto_sync_skcipher	*skcipher;
> +		struct crypto_skcipher		*skcipher;
>   		struct crypto_ahash		*ahash;
>   		struct crypto_aead		*aead;
>   	} fallback;
> 

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