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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8E498C433F5 for ; Fri, 25 Feb 2022 13:17:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238277AbiBYNRj (ORCPT ); Fri, 25 Feb 2022 08:17:39 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45746 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241028AbiBYNRg (ORCPT ); Fri, 25 Feb 2022 08:17:36 -0500 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6B41AE33BA for ; Fri, 25 Feb 2022 05:16:59 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; 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=gcLU/vg5cewrZSDPx6TyApuKFbZkoUXSLj0y9z6R8Vs=; b=kNwTCnRyfhWL3uD70G4U8KIVqz sY9HFyXny7cGN6e54CjSPbSfbxlEtWUURwNO1LjWDjtBsj8W+qtz0UR/Y8LMiten7EdKb2uH8IHQ4 RGnpC50hYlMY6cuR3WTbLIrLn5wnVt/Rq35fZsX8xDGCXcsyiyOOOgqUte5rizwFHw0rWlwqxgg10 ShuhzQFN8R6y4fSTqVKH4N4YW/RnRKSVgtDXaXtRilLwH2IOoOaYjMWBfBqOW3DvBBZ63ZCXk9ilc eJxaxestRjhZnZ41qXqPXDr+f7R2YOKDPnhzHk3bdpkOVfGJJRKZW22XZqM/3Uiak1S+RZZC/kZtJ JD4WZDbA==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1nNaSe-005nss-GQ; Fri, 25 Feb 2022 13:16:40 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 8426C30081D; Fri, 25 Feb 2022 14:16:39 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 4552B235EF288; Fri, 25 Feb 2022 14:16:39 +0100 (CET) Date: Fri, 25 Feb 2022 14:16:39 +0100 From: Peter Zijlstra To: Josh Poimboeuf Cc: x86@kernel.org, joao@overdrivepizza.com, hjl.tools@gmail.com, andrew.cooper3@citrix.com, linux-kernel@vger.kernel.org, ndesaulniers@google.com, keescook@chromium.org, samitolvanen@google.com, mark.rutland@arm.com, alyssa.milburn@intel.com, mbenes@suse.cz, rostedt@goodmis.org, mhiramat@kernel.org, alexei.starovoitov@gmail.com Subject: Re: [PATCH v2 28/39] x86/ibt,xen: Sprinkle the ENDBR Message-ID: References: <20220224145138.952963315@infradead.org> <20220224151323.661210297@infradead.org> <20220225005440.mvz4jtxwq5ttcu77@treble> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220225005440.mvz4jtxwq5ttcu77@treble> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Feb 24, 2022 at 04:54:40PM -0800, Josh Poimboeuf wrote: > On Thu, Feb 24, 2022 at 03:52:06PM +0100, Peter Zijlstra wrote: > > +++ b/arch/x86/xen/xen-head.S > > @@ -25,8 +25,11 @@ > > SYM_CODE_START(hypercall_page) > > .rept (PAGE_SIZE / 32) > > UNWIND_HINT_FUNC > > - .skip 31, 0x90 > > - RET > > + ANNOTATE_NOENDBR > > + /* > > + * Xen will write the hypercall page, and sort out ENDBR. > > + */ > > + .skip 32, 0xcc > > I seem to remember this UNWIND_HINT_FUNC was only there to silence > warnings because of the ret. With the ret gone, maybe the hint can be > dropped as well. vmlinux.o: warning: objtool: xen_hypercall_iret()+0x0: stack state mismatch: cfa1=4+8 cfa2=-1+0 and back it goes ;-)