Received-SPF: pass (google.com: domain of linux-crypto-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
MIME-Version: 1.0
References: <20200930065617.934638-1-palmerdabbelt@google.com>
 <20201005061918.GB1856@infradead.org> <CAMj1kXFC=6G1pqFAcjASrKJfzguO3k9Rv-7NsmTaX8qNre5TGw@mail.gmail.com>
 <2588700.mWSkj6HvKX@tauon.chronox.de>
In-Reply-To: <2588700.mWSkj6HvKX@tauon.chronox.de>
From:   Ard Biesheuvel <ardb@kernel.org>
Date:   Mon, 5 Oct 2020 08:44:39 +0200
Message-ID: <CAMj1kXFL4gfrK1+zRG9sajTk62yRh3WzBG46KfKD=iM=VQMTAQ@mail.gmail.com>
Subject: Re: [PATCH] crypto: jitterentropy - bind statically into kernel
To:     Stephan Mueller <smueller@chronox.de>
Cc:     Christoph Hellwig <hch@infradead.org>,
        Palmer Dabbelt <palmerdabbelt@google.com>,
        linux-riscv <linux-riscv@lists.infradead.org>,
        Android Kernel Team <kernel-team@android.com>,
        kernel test robot <lkp@intel.com>,
        Linux Crypto Mailing List <linux-crypto@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

On Mon, 5 Oct 2020 at 08:40, Stephan Mueller <smueller@chronox.de> wrote:
>
> Am Montag, 5. Oktober 2020, 08:24:46 CEST schrieb Ard Biesheuvel:
>
> Hi Ard,
>
> > If jitterentropy is a special case, we could put a alternate
> > non-'static inline' version of random_get_entropy() in the core
> > kernel, and only export it if JITTER_ENTROPY is built as a module in
> > the first place. But I'd prefer it if jitterentropy switches to an API
> > that is suitable for driver consumption.
>
> Which API do you have in mind? In user space, I use
> clock_gettime(CLOCK_REALTIME) which also considers the clock source.
>

AFAICT, that call is backed by ktime_get_real_ts64(), which is already
being exported to modules.

Could you please check whether that works for your driver?