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From: Arnd Bergmann <arnd@arndb.de>
To: y2038@lists.linaro.org
Cc: herbert@gondor.apana.org.au,
	Alexander Kuleshov <kuleshovmail@gmail.com>,
	Stephan Mueller <smueller@chronox.de>,
	linux-kernel@vger.kernel.org,
	John Stultz <john.stultz@linaro.org>,
	linux-crypto@vger.kernel.org,
	"David S. Miller" <davem@davemloft.net>,
	Kees Cook <keescook@chromium.org>
Subject: Re: [PATCH v2] crypto: Jitter RNG - use ktime_get_ns as fallback
Date: Wed, 22 Jun 2016 22:16:03 +0200	[thread overview]
Message-ID: <3682553.NXCjD7b2Nc@wuerfel> (raw)
In-Reply-To: <2249326.PVY2Dy3CIm@positron.chronox.de>

On Wednesday, June 22, 2016 7:26:06 PM CEST Stephan Mueller wrote:
> As part of the Y2038 development, __getnstimeofday is not supposed to be
> used any more. It is now replaced with ktime_get_ns. The Jitter RNG uses
> the time stamp to measure the execution time of a given code path and
> tries to detect variations in the execution time. Therefore, the only
> requirement the Jitter RNG has, is a sufficient high resolution to
> detect these variations.
> 
> The change was tested on x86 to show an identical behavior as RDTSC. The
> used test code simply measures the execution time of the heart of the
> RNG:
> 
>         jent_get_nstime(&time);
>         jent_memaccess(ec, min);
>         jent_fold_time(NULL, time, &folded, min);
>         jent_get_nstime(&time2);
>         return ((time2 - time));
> 
> Signed-off-by: Stephan Mueller <smueller@chronox.de>
> ---
> 

Acked-by: Arnd Bergmann <arnd@arndb.de>
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  parent reply	other threads:[~2016-06-22 20:16 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-06-22 17:26 [PATCH v2] crypto: Jitter RNG - use ktime_get_ns as fallback Stephan Mueller
2016-06-22 17:59 ` John Stultz
2016-06-22 20:16 ` Arnd Bergmann [this message]
2016-06-24 13:31 ` Herbert Xu

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