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 A50F8C282DD for ; Wed, 8 Jan 2020 17:22:13 +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 76DB520705 for ; Wed, 8 Jan 2020 17:22:13 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="lMYO0nKl" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 76DB520705 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=MUBnooYZsmxWC1Piow5eiPi2L9jAbg3t3pcaeu05oL8=; b=lMYO0nKl/xDb0D 3vwQ1rjH6AlKkS/in907UDQpWc9zLShMOlQ/JLtKRqYFk218VVf/U2Hda+SI8Wn6ZAlS8Z/JptDWC 1a/st7dbuB6jb/DX+X7XR/4xRXBq4EZ/pfuwfmvdfAY6QINVmLtv3P9J9X9RF/QbtBgvqHdG9+/VT Ehf8j/JtK/EU3EsiTfMkFqDvKQgj6OGtKxkdmAWjmUjt4frNAP0EEI9Toy4SJK4b3zz+SFHOlS+SA TbRzEJj7EyvIYVGzdvRzMz+XijeERaSP4ihbyfVhblJd/wGFeBhuGHi9DbRC3WdQyaXF09kS7YpzJ wB1E2iWaU1kpnjhD9mAg==; 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 1ipF1y-0001qL-Fn; Wed, 08 Jan 2020 17:22:06 +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 1ipF1v-0001py-Jx for linux-arm-kernel@lists.infradead.org; Wed, 08 Jan 2020 17:22:04 +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 9F15A1FB; Wed, 8 Jan 2020 09:22:02 -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 A06DC3F534; Wed, 8 Jan 2020 09:22:01 -0800 (PST) Date: Wed, 8 Jan 2020 17:21:59 +0000 From: Mark Rutland To: Mark Brown Subject: Re: [PATCH v8 3/3] arm64: Use v8.5-RNG entropy for KASLR seed Message-ID: <20200108172159.GJ49203@lakrids.cambridge.arm.com> References: <20200107183540.54794-1-broonie@kernel.org> <20200107183540.54794-4-broonie@kernel.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20200107183540.54794-4-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-20200108_092203_701068_F1AB68D5 X-CRM114-Status: GOOD ( 17.86 ) 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: suzuki.poulose@arm.com, Catalin Marinas , ard.biesheuvel@linaro.org, Richard Henderson , Will Deacon , 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+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Tue, Jan 07, 2020 at 06:35:40PM +0000, Mark Brown wrote: > When seeding KALSR on a system where we have architecture level random > number generation make use of that entropy, mixing it in with the seed > passed by the bootloader. Since this is run very early in init before > feature detection is complete we open code rather than use archrandom.h. > > Signed-off-by: Mark Brown > --- > arch/arm64/kernel/kaslr.c | 15 ++++++++++++++- > 1 file changed, 14 insertions(+), 1 deletion(-) > > diff --git a/arch/arm64/kernel/kaslr.c b/arch/arm64/kernel/kaslr.c > index 2a11a962e571..fc38c4c25eb6 100644 > --- a/arch/arm64/kernel/kaslr.c > +++ b/arch/arm64/kernel/kaslr.c > @@ -81,7 +81,8 @@ static __init const u8 *kaslr_get_cmdline(void *fdt) > u64 __init kaslr_early_init(u64 dt_phys) > { > void *fdt; > - u64 seed, offset, mask, module_range; > + u64 seed, offset, mask, module_range, ftr; > + unsigned long raw; > const u8 *cmdline, *str; > int size; > > @@ -120,6 +121,18 @@ u64 __init kaslr_early_init(u64 dt_phys) > return 0; > } > > + /* > + * Mix in any entropy obtainable architecturally, open coded > + * since this runs extremely early. > + */ > + if (IS_ENABLED(CONFIG_ARCH_RANDOM)) { > + ftr = read_sysreg_s(SYS_ID_AA64ISAR0_EL1); > + if ((ftr >> ID_AA64ISAR0_RNDR_SHIFT) & 0xf) { > + if (__arm64_rndr(&raw)) > + seed += raw; > + } > + } This looks good. If we add the helper I suggest in patch 2, we can reduce this down to: /* Mix in any entropy obtainable architecturally */ if (__early_cpu_has_rndr()) { unsigned long raw; if (__arm64_rndr(&raw)) seed += raw; } ... which keeps all the RNG bits in one place. Thanks, Mark. > + > if (!seed) { > kaslr_status = KASLR_DISABLED_NO_SEED; > return 0; > -- > 2.20.1 > _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel