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=-8.2 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,URIBL_BLOCKED,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 E6C22C5B57A for ; Fri, 28 Jun 2019 09:35:54 +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 BFD902147A for ; Fri, 28 Jun 2019 09:35:54 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="jt3tHthB" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org BFD902147A 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=F0qI0S89fhYIjmg/9z3ZiI9YKpTfpm9uUJT9QS61b6g=; b=jt3tHthBVaQLwQ Pzr+al39OHhXfc/lj/3OtyusSnHpyyF7G/MM7be7XiHNZEK8agwkcY4EY3LIaA6sHWmOcYxpqWmLt FyajrQoWb8LNblZxfkazXveFkafftzsMsfUhnx2afnSuA7582FUm5OM+3KsItNBXYvfWW0LwmD28b qlmlpVj9cRuK8Dwe27bJWJEUYNX0+O15LPHZ7hJxx9atRU/fKdgqm0u/ypB3A0J+IQ7yFeM0UcNEY d1T9TJIv0UYx7ca0InfeiJ79+ztXeRdYWlPyVVHhCgYIvB9wo7I/tDKSDPC7XqoKVNnCnfubAc1vk lZgmbIYSCqULjAoE8hnw==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92 #3 (Red Hat Linux)) id 1hgnID-0005FC-MV; Fri, 28 Jun 2019 09:35:41 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.92 #3 (Red Hat Linux)) id 1hgnIA-0005EB-PM for linux-arm-kernel@lists.infradead.org; Fri, 28 Jun 2019 09:35:40 +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 97EB928; Fri, 28 Jun 2019 02:35:34 -0700 (PDT) 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 27E9F3F718; Fri, 28 Jun 2019 02:35:32 -0700 (PDT) Date: Fri, 28 Jun 2019 10:35:30 +0100 From: Mark Rutland To: Hsin-Yi Wang Subject: Re: [PATCH v6 2/3] fdt: add support for rng-seed Message-ID: <20190628093529.GB36437@lakrids.cambridge.arm.com> References: <20190612043258.166048-1-hsinyi@chromium.org> <20190612043258.166048-3-hsinyi@chromium.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20190612043258.166048-3-hsinyi@chromium.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-20190628_023538_866810_13D9E9C7 X-CRM114-Status: GOOD ( 20.51 ) 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: devicetree@vger.kernel.org, Yu Zhao , Kees Cook , Ard Biesheuvel , Catalin Marinas , Stephen Boyd , Will Deacon , linux-kernel@vger.kernel.org, Mike Rapoport , Jun Yao , Miles Chen , Rob Herring , James Morse , Andrew Murray , Andrew Morton , Laura Abbott , Frank Rowand , linux-arm-kernel@lists.infradead.org, Robin Murphy 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 Wed, Jun 12, 2019 at 12:33:00PM +0800, Hsin-Yi Wang wrote: > Introducing a chosen node, rng-seed, which is an entropy that can be > passed to kernel called very early to increase initial device > randomness. Bootloader should provide this entropy and the value is > read from /chosen/rng-seed in DT. Could you please elaborate on this? * What is this initial entropy used by, and why is this important? I assume that devices which can populate this will have a HW RNG that the kernel will eventually make use of. * How much entropy is necessary or sufficient? * Why is the DT the right mechanism for this? Thanks, Mark. > > Signed-off-by: Hsin-Yi Wang > Reviewed-by: Stephen Boyd > --- > change log v5->v6: > * remove Documentation change > --- > drivers/of/fdt.c | 10 ++++++++++ > 1 file changed, 10 insertions(+) > > diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c > index 3d36b5afd9bd..369130dbd42c 100644 > --- a/drivers/of/fdt.c > +++ b/drivers/of/fdt.c > @@ -24,6 +24,7 @@ > #include > #include > #include > +#include > > #include /* for COMMAND_LINE_SIZE */ > #include > @@ -1052,6 +1053,7 @@ int __init early_init_dt_scan_chosen(unsigned long node, const char *uname, > { > int l; > const char *p; > + const void *rng_seed; > > pr_debug("search \"chosen\", depth: %d, uname: %s\n", depth, uname); > > @@ -1086,6 +1088,14 @@ int __init early_init_dt_scan_chosen(unsigned long node, const char *uname, > > pr_debug("Command line is: %s\n", (char*)data); > > + rng_seed = of_get_flat_dt_prop(node, "rng-seed", &l); > + if (rng_seed && l > 0) { > + add_device_randomness(rng_seed, l); > + > + /* try to clear seed so it won't be found. */ > + fdt_nop_property(initial_boot_params, node, "rng-seed"); > + } > + > /* break now */ > return 1; > } > -- > 2.20.1 > _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel