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=-16.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_2 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 DE331C4338F for ; Fri, 30 Jul 2021 15:19:09 +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 AE8B660F46 for ; Fri, 30 Jul 2021 15:19:09 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org AE8B660F46 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-ID:Subject:Cc: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=T4XL3tlHR3v73BubJfH8Fftmiv6kr/cfNob9ZfEpnvM=; b=hDqNy+9aRSNMhm jK1+4NizKc4NXZtRMt+9nufTUEh9w7L5IIhod/GJJbZrvM/POhY9sD9BSXybPFcWOK6EdB9zL64so PmRaDC677DFwvn0C5Ia5uM6x/fJH/kxvEqlHHIr7eVHDGvrsVVbM4rq8XQiSalVfeUip3p3iEkYU0 EXkyT7NxpeZ0yEg5jN4gTEiDYZhyQia+41dBDsDqiNDIHb3UkKIDpI0yS36hAMnHntCSL8cckiGTL VUUFyN1B/IMDZUvvk2h7TzlNrvqe01zV//6VdZHl3urH4YCuZA9MN/Em+A4UpAmpTP5eEw2MPhx7x 0hjqzWGfOyeqtP+op6hw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1m9UFr-009EVI-Iu; Fri, 30 Jul 2021 15:16:55 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1m9UCp-009DPM-Uu for linux-arm-kernel@lists.infradead.org; Fri, 30 Jul 2021 15:13:49 +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 E3B1E11B3; Fri, 30 Jul 2021 08:13:46 -0700 (PDT) Received: from slackpad.fritz.box (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 49ED33F66F; Fri, 30 Jul 2021 08:13:46 -0700 (PDT) Date: Fri, 30 Jul 2021 16:13:05 +0100 From: Andre Przywara To: Mark Rutland Cc: linux-arm-kernel@lists.infradead.org, Jaxson.Han@arm.com, Wei.Chen@arm.com Subject: Re: [boot-wrapper PATCH 04/12] Remove `flag_no_el3` Message-ID: <20210730161305.4064f576@slackpad.fritz.box> In-Reply-To: <20210729152050.23635-5-mark.rutland@arm.com> References: <20210729152050.23635-1-mark.rutland@arm.com> <20210729152050.23635-5-mark.rutland@arm.com> Organization: Arm Ltd. X-Mailer: Claws Mail 3.17.1 (GTK+ 2.24.31; x86_64-slackware-linux-gnu) MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210730_081348_110267_E89F0C9F X-CRM114-Status: GOOD ( 15.98 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , 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 Thu, 29 Jul 2021 16:20:42 +0100 Mark Rutland wrote: Hi, > We set `flag_no_el3` when not booted at EL3 / monitor mode, and > subsequently we use this to determine whether we need to drop exception > level before entering Linux. As this can be derived from CurrentEL or > CPSR, the flag itself is redundant, and we can defer the check until > we're about to enter Linux. > > In future this will allow more logic to be converted into C, where it > will be easier to handle architectural variants. > > Signed-off-by: Mark Rutland > --- > arch/aarch32/boot.S | 14 +++----------- > arch/aarch64/boot.S | 13 ++----------- > 2 files changed, 5 insertions(+), 22 deletions(-) > > diff --git a/arch/aarch32/boot.S b/arch/aarch32/boot.S > index 2a85ad5..0bd1ca2 100644 > --- a/arch/aarch32/boot.S > +++ b/arch/aarch32/boot.S > @@ -31,9 +31,6 @@ ENTRY(_start) > cmp r0, #PSR_HYP > bne _switch_monitor Can't this become "beq start_no_el3" now? > > - mov r0, #1 > - ldr r1, =flag_no_el3 > - str r0, [r1] > b start_no_el3 > > _switch_monitor: > @@ -89,9 +86,9 @@ ENTRY(jump_kernel) > ldr lr, [r5], #4 > ldm r5, {r0 - r2} > > - ldr r4, =flag_no_el3 > - ldr r4, [r4] > - cmp r4, #1 > + mrs r4, cpsr > + and r4, #PSR_MODE_MASK > + cmp r4, #PSR_MON Is comparing explicitly against monitor mode the right thing? IIRC normally we come out of reset in secure SVC, and this *is* EL3 (the highest implemented exception level), from an ARMv8 perspective. The old code did compare against HYP, which is probably what we want and is also one of the few modes we are sure of being not EL3. > bxeq lr @ no EL3 > > ldr r4, =SPSR_KERNEL > @@ -113,8 +110,3 @@ boot_vectors: > b . > b . > b . > - > - .section .data > - .align 2 > -flag_no_el3: > - .long 0 > diff --git a/arch/aarch64/boot.S b/arch/aarch64/boot.S > index 37759ce..fae0188 100644 > --- a/arch/aarch64/boot.S > +++ b/arch/aarch64/boot.S > @@ -28,10 +28,6 @@ _start: > cmp x0, #CURRENTEL_EL3 > b.eq 1f Can't this become "b.ne start_no_el3" now? Cheers, Andre > > - mov w0, #1 > - ldr x1, =flag_no_el3 > - str w0, [x1] > - > b start_no_el3 > > 1: mov x0, #0x30 // RES1 > @@ -140,8 +136,8 @@ jump_kernel: > bl find_logical_id > bl setup_stack // Reset stack pointer > > - ldr w0, flag_no_el3 > - cmp w0, #0 // Prepare Z flag > + mrs x0, CurrentEl > + cmp w0, #CURRENTEL_EL3 // Prepare Z flag > > mov x0, x20 > mov x1, x21 > @@ -164,8 +160,3 @@ jump_kernel: > eret > > .ltorg > - > - .data > - .align 3 > -flag_no_el3: > - .long 0 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel