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[147.75.199.223]) by mx.google.com with ESMTPS id n19-20020ae9c313000000b0078eb9923f25si2700176qkg.525.2024.04.18.17.32.04 for (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 18 Apr 2024 17:32:05 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel+bounces-150886-linux.lists.archive=gmail.com@vger.kernel.org designates 147.75.199.223 as permitted sender) client-ip=147.75.199.223; Authentication-Results: mx.google.com; dkim=pass header.i=@kernel.org header.s=k20201202 header.b=D3OOXQdd; arc=pass (i=1 dkim=pass dkdomain=kernel.org); spf=pass (google.com: domain of linux-kernel+bounces-150886-linux.lists.archive=gmail.com@vger.kernel.org designates 147.75.199.223 as permitted sender) smtp.mailfrom="linux-kernel+bounces-150886-linux.lists.archive=gmail.com@vger.kernel.org"; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=kernel.org Received: from smtp.subspace.kernel.org (wormhole.subspace.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ny.mirrors.kernel.org (Postfix) with ESMTPS id 71B171C212D9 for ; Fri, 19 Apr 2024 00:31:49 +0000 (UTC) Received: from localhost.localdomain (localhost.localdomain [127.0.0.1]) by smtp.subspace.kernel.org (Postfix) with ESMTP id CC551818; Fri, 19 Apr 2024 00:31:43 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="D3OOXQdd" Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id F01B2384 for ; Fri, 19 Apr 2024 00:31:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1713486703; cv=none; b=WN2g1IpvN0oPjkUjJvJR9gMzZkDZU0t7NULv6VNmMrW6sgkKgEDWn2jzSzTqOaGACiXZbjBKWtvY1mNscYXHgbxgdbJRTFbDAqMDDHB9uGySq+prOCmrNJP20pOVQ5wR65lms132mozYyDlLRnDuhKBG37gU9DduXsmQyu4aIa8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1713486703; c=relaxed/simple; bh=afqxxhV/UjurKNem0VkvBnc+8N2Ycl93sGw2OtrQE3g=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=iJQ4imTchIP5g1N49thaAG4ZX3HXpbdNJyFJANxQZqX3lUV041LLIf3km5AVJC6zWVzbrMgRdc1T4RT6zy3+rbk19g+bzS3zgWUtIWs0VKpiyg03QL1BU/LkUd90orEL31I4Z0g0byYqDFUd0GLae7ZoBfvfPWVBApCByG36N4U= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=D3OOXQdd; arc=none smtp.client-ip=10.30.226.201 Received: by smtp.kernel.org (Postfix) with ESMTPSA id AC0FEC113CC; Fri, 19 Apr 2024 00:31:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1713486702; bh=afqxxhV/UjurKNem0VkvBnc+8N2Ycl93sGw2OtrQE3g=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=D3OOXQdd0CfBA7jmq53UJ3aUWUC7X9gsdddfI65858DtpBTUuokqD4A8iKJUM4hsD EIQPenMEUTHW7C9c/2ystoSStr1xjhIG2+IIfZJ/wYXxqcUVwr10sQdsSgbPlmLpvL ro6ZR1LMdAKSshTaDOilLEl6BcarUu69RVVUrkeAqO0pWB4+5VKZbgLR3wdQH/B1ZZ GiH5Cns8jlMnvJ+R7hu2eHlSWxpRaHFA+1CDRWepM69Ar6LidbuteeaYEiPy5yCciu NNoJ1zfrKjGIRTvFpGU+I0sY0AaHqF7IRPnTHXIy/cLsEKpTHnUx7WPpOo+eA0MHEl QTvANbk1wJlBA== Date: Thu, 18 Apr 2024 17:31:39 -0700 From: Josh Poimboeuf To: Christoph Hellwig Cc: x86@kernel.org, linux-kernel@vger.kernel.org, Linus Torvalds , Daniel Sneddon , Pawan Gupta , Thomas Gleixner , Alexandre Chartre , Konrad Rzeszutek Wilk , Peter Zijlstra , Greg Kroah-Hartman , Sean Christopherson , Andrew Cooper , Dave Hansen , Nikolay Borisov , KP Singh , Waiman Long , Borislav Petkov , Ingo Molnar Subject: Re: [PATCH v3] x86/bugs: Only harden syscalls when needed Message-ID: <20240419003139.kjfepjhjcjzexqpr@treble> References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: On Wed, Apr 17, 2024 at 11:50:55PM -0700, Christoph Hellwig wrote: > On Tue, Apr 16, 2024 at 04:02:21PM -0700, Josh Poimboeuf wrote: > > Syscall hardening (i.e., converting the syscall indirect branch to a > > series of direct branches) may cause performance regressions in certain > > scenarios. > > Maybe spell out the scenarios, as this just sounds like hand waiving > right now.. Will do. -- Josh