From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A048CC41604 for ; Wed, 7 Oct 2020 14:45:48 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 2C4D3208C7 for ; Wed, 7 Oct 2020 14:45:48 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="qxdbRv7/" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2C4D3208C7 Authentication-Results: mail.kernel.org; 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Message-ID: Date: Wed, 7 Oct 2020 15:43:46 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.12.0 MIME-Version: 1.0 In-Reply-To: <65057faa-d06b-6baf-4f12-9587cacbe3a9@arm.com> Content-Language: en-GB X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20201007_104435_012919_DB110AD3 X-CRM114-Status: GOOD ( 22.68 ) 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 , Lorenzo Pieralisi , Catalin Marinas , Richard Henderson , linux-kernel@vger.kernel.org, Mark Brown , Sudeep Holla , Will Deacon , Ard Biesheuvel , linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 07/10/2020 15:16, James Morse wrote: Hi, > On 06/10/2020 21:18, Andre Przywara wrote: >> The ARM architected TRNG firmware interface, described in ARM spec >> DEN0098[1], defines an ARM SMCCC based interface to a true random number >> generator, provided by firmware. >> This can be discovered via the SMCCC >=v1.1 interface, and provides >> up to 192 bits of entropy per call. >> >> Hook this SMC call into arm64's arch_get_random_*() implementation, >> coming to the rescue when the CPU does not implement the ARM v8.5 RNG >> system registers. >> >> For the detection, we piggy back on the PSCI/SMCCC discovery (which gives >> us the conduit to use: hvc or smc), then try to call the >> ARM_SMCCC_TRNG_VERSION function, which returns -1 if this interface is >> not implemented. > >> arch/arm64/include/asm/archrandom.h | 83 +++++++++++++++++++++++++---- >> 1 file changed, 73 insertions(+), 10 deletions(-) > >> diff --git a/arch/arm64/include/asm/archrandom.h b/arch/arm64/include/asm/archrandom.h >> index ffb1a40d5475..b6c291c42a48 100644 >> --- a/arch/arm64/include/asm/archrandom.h >> +++ b/arch/arm64/include/asm/archrandom.h >> @@ -7,6 +7,13 @@ >> #include >> #include >> #include >> +#include >> + >> +static enum smc_trng_status { >> + SMC_TRNG_UNKNOWN, >> + SMC_TRNG_NOT_SUPPORTED, >> + SMC_TRNG_SUPPORTED >> +} smc_trng_status = SMC_TRNG_UNKNOWN; > > Doesn't this static variable in a header file mean each file that includes this has its > own copy? Is that intentional? Right, and it's not intentional. It doesn't really break, but since random.h includes archrandom.h, we get an instance everywhere :-( I wasn't too happy with this detection method to begin with (and also not with stuffing everything into a header file), but wanted to accommodate the early case, where PSCI hasn't been initialised yet, and so we don't know the SMCCC conduit. A static key sounds better, but gets a bit hairy with this scenario, I think. Any ideas here? I could copy Ard's solution and introduce random.c, if that makes more sense. Cheers, Andre _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel