linux-kernel - Re: [PATCH 03/13] crypto: x86/sha - yield FPU context during long loops

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Date:   Fri, 30 Dec 2022 17:08:00 +0800
From:   Herbert Xu <herbert@...dor.apana.org.au>
To:     Robert Elliott <elliott@....com>
Cc:     davem@...emloft.net, Jason@...c4.com, ardb@...nel.org,
        ap420073@...il.com, David.Laight@...lab.com, ebiggers@...nel.org,
        tim.c.chen@...ux.intel.com, peter@...jl.ca, tglx@...utronix.de,
        mingo@...hat.com, bp@...en8.de, dave.hansen@...ux.intel.com,
        linux-crypto@...r.kernel.org, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 03/13] crypto: x86/sha - yield FPU context during long
 loops

On Mon, Dec 19, 2022 at 04:02:13PM -0600, Robert Elliott wrote:
>
> diff --git a/arch/x86/crypto/sha1_avx2_x86_64_asm.S b/arch/x86/crypto/sha1_avx2_x86_64_asm.S
> index c3ee9334cb0f..df03fbb2c42c 100644
> --- a/arch/x86/crypto/sha1_avx2_x86_64_asm.S
> +++ b/arch/x86/crypto/sha1_avx2_x86_64_asm.S
> @@ -58,9 +58,9 @@
>  /*
>   * SHA-1 implementation with Intel(R) AVX2 instruction set extensions.
>   *
> - *This implementation is based on the previous SSSE3 release:
> - *Visit http://software.intel.com/en-us/articles/
> - *and refer to improving-the-performance-of-the-secure-hash-algorithm-1/
> + * This implementation is based on the previous SSSE3 release:
> + * Visit http://software.intel.com/en-us/articles/
> + * and refer to improving-the-performance-of-the-secure-hash-algorithm-1/

Could you please leave out changes which are not related to the
main purpose of this patch?

Put them into a separate patch if necessary.

> diff --git a/arch/x86/crypto/sha1_ssse3_glue.c b/arch/x86/crypto/sha1_ssse3_glue.c
> index 44340a1139e0..b269b455fbbe 100644
> --- a/arch/x86/crypto/sha1_ssse3_glue.c
> +++ b/arch/x86/crypto/sha1_ssse3_glue.c
> @@ -41,9 +41,7 @@ static int sha1_update(struct shash_desc *desc, const u8 *data,
>  	 */
>  	BUILD_BUG_ON(offsetof(struct sha1_state, state) != 0);
>  
> -	kernel_fpu_begin();
>  	sha1_base_do_update(desc, data, len, sha1_xform);
> -	kernel_fpu_end();

Moving kernel_fpu_begin/kernel_fpu_end down seems to be entirely
unnecessary as you could already call kernel_fpu_yield deep down
the stack with the current code.

Thanks,
-- 
Email: Herbert Xu <herbert@...dor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt