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From:   Horia Geanta <horia.geanta@nxp.com>
To:     Iuliana Prodan <iuliana.prodan@nxp.com>,
        Herbert Xu <herbert@gondor.apana.org.au>,
        Aymen Sghaier <aymen.sghaier@nxp.com>
CC:     "David S. Miller" <davem@davemloft.net>,
        "linux-crypto@vger.kernel.org" <linux-crypto@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        dl-linux-imx <linux-imx@nxp.com>
Subject: Re: [PATCH v2 08/14] crypto: caam - update rfc4106 sh desc to support
 zero length input
Thread-Topic: [PATCH v2 08/14] crypto: caam - update rfc4106 sh desc to
 support zero length input
Thread-Index: AQHVPcSrFTz96tsd1UekZXZsXHKV8A==
Date:   Fri, 19 Jul 2019 15:38:58 +0000
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 <1563494276-3993-9-git-send-email-iuliana.prodan@nxp.com>
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On 7/19/2019 2:58 AM, Iuliana Prodan wrote:=0A=
> Update share descriptor for rfc4106 to skip instructions in case=0A=
> cryptlen is zero. If no instructions are jumped the DECO hangs and a=0A=
> timeout error is thrown.=0A=
> =0A=
> Signed-off-by: Iuliana Prodan <iuliana.prodan@nxp.com>=0A=
> ---=0A=
>  drivers/crypto/caam/caamalg_desc.c | 46 +++++++++++++++++++++++++-------=
------=0A=
>  drivers/crypto/caam/caamalg_desc.h |  2 +-=0A=
>  2 files changed, 31 insertions(+), 17 deletions(-)=0A=
> =0A=
> diff --git a/drivers/crypto/caam/caamalg_desc.c b/drivers/crypto/caam/caa=
malg_desc.c=0A=
> index 7253183..99f419a 100644=0A=
> --- a/drivers/crypto/caam/caamalg_desc.c=0A=
> +++ b/drivers/crypto/caam/caamalg_desc.c=0A=
> @@ -843,13 +843,16 @@ EXPORT_SYMBOL(cnstr_shdsc_gcm_decap);=0A=
>   * @ivsize: initialization vector size=0A=
>   * @icvsize: integrity check value (ICV) size (truncated or full)=0A=
>   * @is_qi: true when called from caam/qi=0A=
> + *=0A=
> + * Input sequence: AAD | PTXT=0A=
> + * Output sequence: AAD | CTXT | ICV=0A=
> + * AAD length (assoclen), which includes the IV length, is available in =
Math3.=0A=
>   */=0A=
>  void cnstr_shdsc_rfc4106_encap(u32 * const desc, struct alginfo *cdata,=
=0A=
>  			       unsigned int ivsize, unsigned int icvsize,=0A=
>  			       const bool is_qi)=0A=
>  {=0A=
> -	u32 *key_jump_cmd;=0A=
> -=0A=
> +	u32 *key_jump_cmd, *zero_cryptlen_jump_cmd, *skip_instructions;=0A=
>  	init_sh_desc(desc, HDR_SHARE_SERIAL);=0A=
>  =0A=
>  	/* Skip key loading if it is loaded due to sharing */=0A=
> @@ -890,26 +893,25 @@ void cnstr_shdsc_rfc4106_encap(u32 * const desc, st=
ruct alginfo *cdata,=0A=
>  	}=0A=
>  =0A=
>  	append_math_sub_imm_u32(desc, VARSEQINLEN, REG3, IMM, ivsize);=0A=
> -	append_math_add(desc, VARSEQOUTLEN, ZERO, REG3, CAAM_CMD_SZ);=0A=
> +	append_math_add(desc, VARSEQOUTLEN, REG0, REG3, CAAM_CMD_SZ);=0A=
>  =0A=
Why is this needed?=0A=
-all math registers are zero when descriptors start execution=0A=
-all caam hw revisions have support for math instruction=0A=
with ZERO as first operand=0A=
-descriptor size stays the same=0A=
=0A=
> -	/* Read assoc data */=0A=
> +	/* Skip AAD */=0A=
> +	append_seq_fifo_store(desc, 0, FIFOST_TYPE_SKIP | FIFOLDST_VLF);=0A=
> +=0A=
> +	/* Read cryptlen and set this value into VARSEQOUTLEN */=0A=
> +	append_math_sub(desc, VARSEQOUTLEN, SEQINLEN, REG3, CAAM_CMD_SZ);=0A=
> +=0A=
> +	/* If cryptlen is ZERO jump to AAD command */=0A=
> +	zero_cryptlen_jump_cmd =3D append_jump(desc, JUMP_TEST_ALL |=0A=
> +					    JUMP_COND_MATH_Z);=0A=
> +=0A=
> +	/* Read AAD data */=0A=
>  	append_seq_fifo_load(desc, 0, FIFOLD_CLASS_CLASS1 | FIFOLDST_VLF |=0A=
>  			     FIFOLD_TYPE_AAD | FIFOLD_TYPE_FLUSH1);=0A=
>  =0A=
>  	/* Skip IV */=0A=
>  	append_seq_fifo_load(desc, ivsize, FIFOLD_CLASS_SKIP);=0A=
> -=0A=
> -	/* Will read cryptlen bytes */=0A=
> -	append_math_sub(desc, VARSEQINLEN, SEQINLEN, REG0, CAAM_CMD_SZ);=0A=
> -=0A=
> -	/* Workaround for erratum A-005473 (simultaneous SEQ FIFO skips) */=0A=
> -	append_seq_fifo_load(desc, 0, FIFOLD_CLASS_CLASS1 | FIFOLD_TYPE_MSG);=
=0A=
> -=0A=
Erratum workaround is dropped without any explanation.=0A=
=0A=
The trigger condition (SKIPs both in input and output sequence) still exist=
s.=0A=
The descriptor should be validated on a caam with erratum not fixed (era < =
6).=0A=
=0A=
Horia=0A=