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[66.91.136.155]) by smtp.gmail.com with ESMTPSA id o2sm14079920pjo.26.2020.01.13.11.09.12 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 13 Jan 2020 11:09:15 -0800 (PST) Subject: Re: [PATCH v10 2/3] arm64: random: Add data to pool from setup_arch() To: Mark Brown , Will Deacon , Catalin Marinas References: <20200110122341.8445-1-broonie@kernel.org> <20200110122341.8445-3-broonie@kernel.org> From: Richard Henderson Message-ID: <3c22586b-a994-2542-d3be-9de9a59d3606@linaro.org> Date: Mon, 13 Jan 2020 09:09:09 -1000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.2.2 MIME-Version: 1.0 In-Reply-To: <20200110122341.8445-3-broonie@kernel.org> Content-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200113_110916_984845_53B21ED1 X-CRM114-Status: GOOD ( 18.03 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , linux-arm-kernel@lists.infradead.org, Ard Biesheuvel Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 1/10/20 2:23 AM, Mark Brown wrote: > Since the arm64 ARCH_RANDOM implementation is not available until > cpufeature has determined the system capabilities it can't be used by > the generic random code to initialize the entropy pool for early use. > Instead explicitly add some data to the pool from setup_arch() if the > boot CPU supports v8.5-RNG, this is the point recommended by the generic > code. > > Note that we are only adding data here, it will be mixed into the pool > but won't be credited as entropy. There are currently no suitable > interfaces for that at present - extending the random code to provide > those will be done as a future step. Providing data is better than not > doing so as it will still provide an increase in variation in the output > from the random code and there will be no impact on the rate at which > entropy is credited compared to what we have without this patch. > > Signed-off-by: Mark Brown > --- > arch/arm64/include/asm/archrandom.h | 30 +++++++++++++++++++++++++++++ > arch/arm64/kernel/setup.c | 2 ++ > 2 files changed, 32 insertions(+) Reviewed-by: Richard Henderson r~ _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel