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=-6.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no 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 90739C4741F for ; Thu, 1 Oct 2020 11:03:05 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (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 345EA2087D for ; Thu, 1 Oct 2020 11:03:04 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="cj9QArZe" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 345EA2087D Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+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=merlin.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=QxcZufsIvzmFRtW9fI7Wq+irY2pu60Y5Y7jV7yNX6dU=; b=cj9QArZeliwccx7lyRoVjxbnr 8X5/A2lO/cHcRjdeRulIniwnquuXQpLzgiI+FLWysinJPGhAASj620bTrgLFykg1pBMUji3CHFKgC tyX9o7HTsPN9ERyEO0LCjhtnHcSm8j/62YRg5fqGvMIXNYv26WCi+R3VlKEGFrFIrc2CMrNJbMaRF rRXvulY5rN196BwvC93DERjT8O8ydbH+VfYmucNPtVxwm2djmiyrMsSojf1N/e3zol2qtoIJTO3KT JkFAl4y7RKKoGILF223gyvZ9XJ+TigqBETVN6JUtMuJUjBKFTTDseVhBO0xHrLirnZWhN58ubi0Sh fUdS0RQDA==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kNwLM-0000pR-C6; Thu, 01 Oct 2020 11:01:48 +0000 Received: from foss.arm.com ([217.140.110.172]) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kNwLI-0000p5-VF for linux-arm-kernel@lists.infradead.org; Thu, 01 Oct 2020 11:01:45 +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 D71D430E; Thu, 1 Oct 2020 04:01:41 -0700 (PDT) Received: from C02TD0UTHF1T.local (unknown [10.57.51.119]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id C158F3F70D; Thu, 1 Oct 2020 04:01:40 -0700 (PDT) Date: Thu, 1 Oct 2020 12:01:38 +0100 From: Mark Rutland To: James Morse Subject: Re: [PATCH 03/13] arm64: head.S: always initialize PSTATE Message-ID: <20201001110138.GC85649@C02TD0UTHF1T.local> References: <20200925160722.27155-1-mark.rutland@arm.com> <20200925160722.27155-4-mark.rutland@arm.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20201001_070145_063227_08864518 X-CRM114-Status: GOOD ( 19.31 ) 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@arm.com, will@kernel.org, robin.murphy@arm.com, hch@lst.de, 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+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Wed, Sep 30, 2020 at 05:09:47PM +0100, James Morse wrote: > Hi Mark, > > On 25/09/2020 17:07, Mark Rutland wrote: > > As with SCTLR_ELx and other control registers, some PSTATE bits are > > UNKNOWN out-of-reset, and we may not be able to rely on hardware of > > firmware > > (hardware or firmware) Whoops; fixed! [...] > > diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S > > index 9bb07be45249a..b8ee9a62c9b61 100644 > > --- a/arch/arm64/kernel/head.S > > +++ b/arch/arm64/kernel/head.S > > @@ -494,17 +494,22 @@ EXPORT_SYMBOL(kimage_vaddr) > > * booted in EL1 or EL2 respectively. > > */ > > SYM_FUNC_START(init_kernel_el) > > - msr SPsel, #1 // We want to use SP_EL{1,2} > > mrs x0, CurrentEL > > cmp x0, #CurrentEL_EL2 > > - b.eq 1f > > + b.eq init_el2 > > + > > +SYM_INNER_LABEL(init_el1, SYM_L_LOCAL) > > mov_q x0, INIT_SCTLR_EL1_MMU_OFF > > msr sctlr_el1, x0 > > - mov w0, #BOOT_CPU_MODE_EL1 // This cpu booted in EL1 > > > isb > > Could you add a comment covering why this ISB isn't rolled into the ERET? > I'm guessing its in case SCTLR_EL1 previously had v8.5s EOS 'Exception Exit is Context > Synchronizing' clear. Yup, and I had a vague fear that we may gain new bits in future along similar lines. I'll add a note to the top of init_kernel_el, since it applies to all of the ERET cases. I'll also add a (pessimistic) ISB to the install_el2_stub return path to make this clear/consistent. Thanks, Mark. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel