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=-8.3 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham 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 83FAAC33CA2 for ; Fri, 10 Jan 2020 12:35:27 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 5201120721 for ; Fri, 10 Jan 2020 12:35:27 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="KpleA5LS" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5201120721 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=yd/WyYjWUXQzyTSl4L3v5FoWEBiR/4lyOtpemapdcjc=; b=KpleA5LS9oQXHt A1MUNTVJw9IhE1xhQ2Yb10AU0F+to8SMD15D7ee7tmhujrEPdKBqEIphq0FHjmZp7lqa17uKBG58e VTpiF0tH4JWT43ruw551bm5Ct4PR9Pr3RimL53ggoPX4PPh/MEGaG4WVpWHOkjd60ab0BXQQJt2ks MoqHko6mpDyUimb3i+FXiYW7gCjISze7jwGDgUWji6MmBub7bcMaey35/j4eqzpn/wt2YBssxi0H9 EINcwbO+qLoUog6cyD8HGjXMcO12vKgluRg0f/P/Fg4s/2k3m3ft03ae6mY+/ByP5SUGSw6YCl+t2 Y32di517Skq0wQQdHztA==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1iptVe-0005eg-HO; Fri, 10 Jan 2020 12:35:26 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1iptVW-0005ct-JM for linux-arm-kernel@lists.infradead.org; Fri, 10 Jan 2020 12:35:24 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id CBA071063; Fri, 10 Jan 2020 04:35:15 -0800 (PST) Received: from lakrids.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.121.207.14]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id E77373F534; Fri, 10 Jan 2020 04:35:14 -0800 (PST) Date: Fri, 10 Jan 2020 12:35:12 +0000 From: Mark Rutland To: Mark Brown Subject: Re: [PATCH v10 2/3] arm64: random: Add data to pool from setup_arch() Message-ID: <20200110123512.GB31707@lakrids.cambridge.arm.com> References: <20200110122341.8445-1-broonie@kernel.org> <20200110122341.8445-3-broonie@kernel.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20200110122341.8445-3-broonie@kernel.org> User-Agent: Mutt/1.11.1+11 (2f07cb52) (2018-12-01) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200110_043521_132758_110520EF X-CRM114-Status: GOOD ( 26.84 ) 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: Catalin Marinas , Richard Henderson , Will Deacon , 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 Fri, Jan 10, 2020 at 12:23:40PM +0000, 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 This is certainly better than the current state of things so: Reviewed-by: Mark Rutland Thanks, Mark. > --- > arch/arm64/include/asm/archrandom.h | 30 +++++++++++++++++++++++++++++ > arch/arm64/kernel/setup.c | 2 ++ > 2 files changed, 32 insertions(+) > > diff --git a/arch/arm64/include/asm/archrandom.h b/arch/arm64/include/asm/archrandom.h > index 5ea5a1ce5a5f..2eb1db1f0bdf 100644 > --- a/arch/arm64/include/asm/archrandom.h > +++ b/arch/arm64/include/asm/archrandom.h > @@ -59,9 +59,39 @@ static inline bool __must_check arch_get_random_seed_int(unsigned int *v) > return ok; > } > > +static inline bool __init __early_cpu_has_rndr(void) > +{ > + /* Open code as we run prior to the first call to cpufeature. */ > + unsigned long ftr = read_sysreg_s(SYS_ID_AA64ISAR0_EL1); > + return (ftr >> ID_AA64ISAR0_RNDR_SHIFT) & 0xf; > +} > + > +/* > + * Our ARCH_RANDOM implementation does not function until relatively > + * late in the boot when cpufeature has detertmined system > + * capabilities so the core code can't use arch_get_random*() to > + * initialize, instead we call this function to inject data from > + * setup_arch() if the boot CPU supports v8.5-RNG. > + */ > +static inline void __init arm64_add_early_rndr_entropy(void) > +{ > + unsigned long val; > + int i; > + > + if (!__early_cpu_has_rndr()) > + return; > + > + /* Add multiple values to mirror the generic code. */ > + for (i = 0; i < 16; i++) > + if (__arm64_rndr(&val)) > + add_device_randomness(&val, sizeof(val)); > +} > + > #else > > static inline bool __arm64_rndr(unsigned long *v) { return false; } > +static inline bool __init __early_cpu_has_rndr(void) { return false; } > +static inline void __init arm64_add_early_rndr_entropy(void) { } > > #endif /* CONFIG_ARCH_RANDOM */ > #endif /* _ASM_ARCHRANDOM_H */ > diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c > index 56f664561754..170842965a32 100644 > --- a/arch/arm64/kernel/setup.c > +++ b/arch/arm64/kernel/setup.c > @@ -344,6 +344,8 @@ void __init setup_arch(char **cmdline_p) > /* Init percpu seeds for random tags after cpus are set up. */ > kasan_init_tags(); > > + arm64_add_early_rndr_entropy(); > + > #ifdef CONFIG_ARM64_SW_TTBR0_PAN > /* > * Make sure init_thread_info.ttbr0 always generates translation > -- > 2.20.1 > _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel