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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3367AC25B08 for ; Wed, 17 Aug 2022 14:17:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237293AbiHQOR3 (ORCPT ); Wed, 17 Aug 2022 10:17:29 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51382 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235733AbiHQOR0 (ORCPT ); Wed, 17 Aug 2022 10:17:26 -0400 Received: from smtp-relay-internal-0.canonical.com (smtp-relay-internal-0.canonical.com [185.125.188.122]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A19E35FF6B for ; Wed, 17 Aug 2022 07:17:25 -0700 (PDT) Received: from mail-ej1-f69.google.com (mail-ej1-f69.google.com [209.85.218.69]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by smtp-relay-internal-0.canonical.com (Postfix) with ESMTPS id 6144F3F1A1 for ; Wed, 17 Aug 2022 14:17:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=canonical.com; s=20210705; t=1660745843; bh=UhnbamTxs3VD3gP1EyVknpnkcVMqwamj16Y6i5t4shY=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:In-Reply-To; b=ux6T8tOjaHrb/1mNVNCC+ZQTvPa/xM/2J8LEXzvGgeBijwAAeeTCA9HU0ewSboWne /34tW65be6cwJnm0nHdG7S8H8nbSX1AUU/KKhhzWUbDX4kzR8nJoIzd+tghyAnaXJS Wqq1Q0WWFFIyfXa6gxSWM308qB+2O6wozut0uIqN5E/zpHJuZzDMFlxHJFiO+2pSWd l3rMWVarfO+aQ8/1OwVE7GzdHPJDkvWV/EKV7QT2D1QITMAxMOudddBrA+a1w3rCF9 LLF6ioHlFLNY8uUf5twZCxXtmI1ClsLC9o1qmDLuIGYnarENKSaL9/lC96tcmMHxTu vRtTPfu2YNyOg== Received: by mail-ej1-f69.google.com with SMTP id g18-20020a1709065d1200b0073082300e1fso2988726ejt.12 for ; Wed, 17 Aug 2022 07:17:23 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc; bh=UhnbamTxs3VD3gP1EyVknpnkcVMqwamj16Y6i5t4shY=; b=k4j4hBtYaooA3U+hHMFpVK9rvGKJHe4HUrbqCDgG5g1hc+wmJQYwmqipX/MUiZgYE1 Zt2my6+egj52TbBr4TcbGNgvwOAvLNBjYdHgPlKCjEu+SeQ5l/w9n65XFxbfDNXTH2/w HLVpfoecJTrO929MsjL9vgGszLjfGEWCP6ocJNa0lkxSUcD92UtIMLSj//X+vLCfth0W ZJK/pBV6Bh/EXva3dBypb9YaxseoSBkKtjQG87B+rT8D1TgRxEvRzWd2sIsg4SKMMUIj W8XiMk+43cRfT9OHhAafK+7Pl1FAdgRwnKGKWu859kWPTG++FHZDqGSDaI10c3NiyAkl 11Ig== X-Gm-Message-State: ACgBeo12OWTNiT7jdlRdkG/JIZcEcp8RfS/aU6UolY/g9HiBj4YsHzyh PuG2EVI5DiJshKgCU2SIcxYXsnifRmmXD3xm1dobwFkahGLLDhwOkciiISWUNGjP5dNipW/sHov 0qbzzms32As22QT0ig0/jksWBWFmPEiaSdi57GoEI4w== X-Received: by 2002:a05:6402:510c:b0:43e:305c:a4d1 with SMTP id m12-20020a056402510c00b0043e305ca4d1mr22580751edd.35.1660745843113; Wed, 17 Aug 2022 07:17:23 -0700 (PDT) X-Google-Smtp-Source: AA6agR7k6xbfLOi7CnYXs1lgb73zhRMRqr6GJQ0DDpuvO5OWTy6LvD52mGjCtuWGaNHGxw6EwFmtbw== X-Received: by 2002:a05:6402:510c:b0:43e:305c:a4d1 with SMTP id m12-20020a056402510c00b0043e305ca4d1mr22580739edd.35.1660745842934; Wed, 17 Aug 2022 07:17:22 -0700 (PDT) Received: from localhost ([2001:67c:1560:8007::aac:c1b6]) by smtp.gmail.com with ESMTPSA id fd4-20020a1709072a0400b00722f069fd40sm6849274ejc.159.2022.08.17.07.17.22 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 17 Aug 2022 07:17:22 -0700 (PDT) Date: Wed, 17 Aug 2022 16:17:21 +0200 From: Andrea Righi To: Mark Brown Cc: Catalin Marinas , Will Deacon , Greg Kroah-Hartman , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] arm64: head: rely on CONFIG_RANDOM_TRUST_CPU Message-ID: References: <20220817094618.67063-1-andrea.righi@canonical.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Aug 17, 2022 at 02:16:28PM +0100, Mark Brown wrote: > On Wed, Aug 17, 2022 at 11:46:18AM +0200, Andrea Righi wrote: > > The CONFIG_ARCH_RANDOM .config option has been removed by > > commit 9592eef7c16e ("random: remove CONFIG_ARCH_RANDOM"). > > > > Depend on CONFIG_RANDOM_TRUST_CPU to determine whether we can rely on > > __arm64_rndr() to initialize the seed for kaslr. > > > > Fixes: 9592eef7c16e ("random: remove CONFIG_ARCH_RANDOM") > > > -#ifdef CONFIG_ARCH_RANDOM > > +#ifdef CONFIG_RANDOM_TRUST_CPU > > if (!__early_cpu_has_rndr() || > > !__arm64_rndr((unsigned long *)&seed)) > > #endif > > I think the sense here would be more that we should just unconditionally > use RNDR if it's present - previously we'd use the result even if we > didn't have strong trust in the CPU implementation and I don't see why > we'd want to change that. Makes sense, in that case it'd be better to just remove the guard completely, as mentioned by Will. Thanks, -Andrea