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=-14.1 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 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 50507C433B4 for ; Tue, 18 May 2021 16:08:30 +0000 (UTC) Received: from desiato.infradead.org (desiato.infradead.org [90.155.92.199]) (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 BA3C7611AC for ; Tue, 18 May 2021 16:08:29 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org BA3C7611AC 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=desiato.20200630; h=Sender:Content-Transfer-Encoding :Content-Type:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: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=R1tq48HY5XQ/IG4OBm6+UU7XnBbyktwFdf2uWH2+S2U=; b=PbWF794Jrds5rzxNb8Rtm8UBX lMknit0+vTVn66Y7jXnBo5UwCiiNykbzSujHPfNH3+cqGrEhu6heRs5oNIIvjJ7Bn1Vz0PAf/Dsky lfXH7EHd3q5YOQDPBCulOXOTo2/c4fSsS2ZixpRvg0l8SyHyGMNcZn0+Q80Qi+n1ZQs7Iq9fBZx3d 60Bj73XAT9x6WeO6PRRAxH4WCoCJvvtxomTtdvlVPCd60La6ExI8rb7amh8Wme9Wj+Gmz9E2JISeM ii5IgxMeFjca8MLz/UzgfX59lSxg0iNJKlbbGLCT9/jYKB+tG0qFIL52ufpwxiytc0rPoVaX19dhQ pmv1o9beQ==; Received: from localhost ([::1] helo=desiato.infradead.org) by desiato.infradead.org with esmtp (Exim 4.94 #2 (Red Hat Linux)) id 1lj2F6-001GxU-13; Tue, 18 May 2021 16:06:48 +0000 Received: from bombadil.infradead.org ([2607:7c80:54:e::133]) by desiato.infradead.org with esmtps (Exim 4.94 #2 (Red Hat Linux)) id 1lj2F3-001Gx5-0r for linux-arm-kernel@desiato.infradead.org; Tue, 18 May 2021 16:06:45 +0000 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20210309; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=p+lmV9Da8ULoEIZG+0kHzIdnb1gSpq6RXpLubOpCGrM=; b=bFr8ANIpHPr+4QFPlKHFAywetX OvuILHBATiF1gO1kvY92AjegM7kN3tV+0AoCoL3RVqn8FD3Vj7JjEawQG814wSMACYC0q8TWsJoAZ pVJ8EOA+1WEl4DyNxUmI55ELOQ2YxlYTOM4Wae46AMtzVsYEXkxGdxAxD8aelALzoXhvfYrGcyDHy p7Fae0OrvLLqCJZPCCUs/UzLh71Re693QM4ZTGb7YdQWZhyxNautcn5C4JJY16Gcu1C/s8PUDw5N+ L4lWO+vSemy3/aNUigK81aGRAo7hBy/lBOSNatVYstJR2y5jhUKKLA5LB9Qvf/nICze0Ub85x/3AY LGcYSNdw==; Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.94 #2 (Red Hat Linux)) id 1lj2F0-00Emsh-7a for linux-arm-kernel@lists.infradead.org; Tue, 18 May 2021 16:06:43 +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 E7D696D; Tue, 18 May 2021 09:06:39 -0700 (PDT) Received: from C02TD0UTHF1T.local (unknown [10.57.6.226]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 6AF2F3F73B; Tue, 18 May 2021 09:06:37 -0700 (PDT) Date: Tue, 18 May 2021 17:06:34 +0100 From: Mark Rutland To: Ard Biesheuvel Cc: Fuad Tabba , Linux ARM , Will Deacon , Catalin Marinas , Marc Zyngier , James Morse , Alexandru Elisei , Suzuki K Poulose , Robin Murphy Subject: Re: [PATCH v2 04/16] arm64: Downgrade flush_icache_range to invalidate Message-ID: <20210518160634.GO82842@C02TD0UTHF1T.local> References: <20210517075124.152151-1-tabba@google.com> <20210517075124.152151-5-tabba@google.com> <20210518155342.GL82842@C02TD0UTHF1T.local> 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-20210518_090642_341610_E8AFACF7 X-CRM114-Status: GOOD ( 26.89 ) 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 Tue, May 18, 2021 at 06:02:32PM +0200, Ard Biesheuvel wrote: > On Tue, 18 May 2021 at 17:53, Mark Rutland wrote: > > > > On Mon, May 17, 2021 at 08:51:12AM +0100, Fuad Tabba wrote: > > > Since __flush_dcache_area is called right before, > > > invalidate_icache_range is sufficient in this case. > > > > > > Rewrite the comment to better explain the rationale behind the > > > cache maintenance operations used here. > > > > > > No functional change intended. > > > Possible performance impact due to invalidating only the icache > > > rather than invalidating and cleaning both caches. > > > > > > Reported-by: Catalin Marinas > > > Reported-by: Will Deacon > > > Link: https://lore.kernel.org/linux-arch/20200511110014.lb9PEahJ4hVOYrbwIb_qUHXyNy9KQzNFdb_I3YlzY6A@z/ > > > Signed-off-by: Fuad Tabba > > > --- > > > arch/arm64/kernel/machine_kexec.c | 10 +++++++--- > > > 1 file changed, 7 insertions(+), 3 deletions(-) > > > > > > diff --git a/arch/arm64/kernel/machine_kexec.c b/arch/arm64/kernel/machine_kexec.c > > > index 90a335c74442..ecd8915e02e1 100644 > > > --- a/arch/arm64/kernel/machine_kexec.c > > > +++ b/arch/arm64/kernel/machine_kexec.c > > > @@ -68,10 +68,14 @@ int machine_kexec_post_load(struct kimage *kimage) > > > kimage->arch.kern_reloc = __pa(reloc_code); > > > kexec_image_info(kimage); > > > > > > - /* Flush the reloc_code in preparation for its execution. */ > > > + /* > > > + * For execution with the MMU off and I-cache on, reloc_code needs to be > > > + * cleaned to the PoC and invalidated from the I-cache. > > > + */ > > > > Minor nit, but the I-cache is *always* on (SCTLR.I affects the > > attributes used for fetches into the I-caches), so it would be slightly > > better to drop the "and I-cache on" words. > > This may be true, but it may not be obvious to someone reading the > 'MMU off' part of the comment. Bottom line is that we will be running > in a mode where we may hit in the I-cache, so it needs to be > invalidated. If we miss in the I-cache, we should fetch from the PoC, > hence the D-cache clean. No disagreement there. I literally meant dropping the words "and I-cache on", leaving the whole comment as: /* * For execution with the MMU off, reloc_code needs to be * cleaned to the PoC and invalidated from the I-cache. */ Thanks, Mark. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel