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

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Message-ID: <Y8TFc84dm3hSVHv5@gondor.apana.org.au>
Date:   Mon, 16 Jan 2023 11:33:07 +0800
From:   Herbert Xu <herbert@...dor.apana.org.au>
To:     "Elliott, Robert (Servers)" <elliott@....com>
Cc:     Eric Biggers <ebiggers@...nel.org>,
        "davem@...emloft.net" <davem@...emloft.net>,
        "Jason@...c4.com" <Jason@...c4.com>,
        "ardb@...nel.org" <ardb@...nel.org>,
        "ap420073@...il.com" <ap420073@...il.com>,
        "David.Laight@...lab.com" <David.Laight@...lab.com>,
        "tim.c.chen@...ux.intel.com" <tim.c.chen@...ux.intel.com>,
        "peter@...jl.ca" <peter@...jl.ca>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "mingo@...hat.com" <mingo@...hat.com>,
        "bp@...en8.de" <bp@...en8.de>,
        "dave.hansen@...ux.intel.com" <dave.hansen@...ux.intel.com>,
        "linux-crypto@...r.kernel.org" <linux-crypto@...r.kernel.org>,
        "x86@...nel.org" <x86@...nel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 03/13] crypto: x86/sha - yield FPU context during long
 loops

On Fri, Jan 13, 2023 at 07:35:07PM +0000, Elliott, Robert (Servers) wrote:
>
> pkcs_digest() uses shash like this:
>         /* Allocate the hashing algorithm we're going to need and find out how
>          * big the hash operational data will be.
>          */
>         tfm = crypto_alloc_shash(sinfo->sig->hash_algo, 0, 0);
>         if (IS_ERR(tfm))
>                 return (PTR_ERR(tfm) == -ENOENT) ? -ENOPKG : PTR_ERR(tfm);
> 
>         desc_size = crypto_shash_descsize(tfm) + sizeof(*desc);
>         sig->digest_size = crypto_shash_digestsize(tfm);
> 
>         ret = -ENOMEM;
>         sig->digest = kmalloc(sig->digest_size, GFP_KERNEL);
>         if (!sig->digest)
>                 goto error_no_desc;
> 
>         desc = kzalloc(desc_size, GFP_KERNEL);
>         if (!desc)
>                 goto error_no_desc;
> 
>         desc->tfm   = tfm;
> 
>         /* Digest the message [RFC2315 9.3] */
>         ret = crypto_shash_digest(desc, pkcs7->data, pkcs7->data_len,
>                                   sig->digest);
>         if (ret < 0)
>                 goto error;
>         pr_devel("MsgDigest = [%*ph]\n", 8, sig->digest);

As this path is sleepable, the conversion should be fairly trivial
with crypto_wait_req.

Cheers,
-- 
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