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[2620:137:e000::1:20]) by mx.google.com with ESMTP id w63-20020a623042000000b0064d5b6864d1si878026pfw.232.2023.06.02.08.36.29; Fri, 02 Jun 2023 08:36:46 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=pass header.i=@infradead.org header.s=desiato.20200630 header.b=GtixR3ar; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236100AbjFBPQu (ORCPT + 99 others); Fri, 2 Jun 2023 11:16:50 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37124 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235698AbjFBPQt (ORCPT ); Fri, 2 Jun 2023 11:16:49 -0400 Received: from desiato.infradead.org (desiato.infradead.org [IPv6:2001:8b0:10b:1:d65d:64ff:fe57:4e05]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3DC3B136 for ; Fri, 2 Jun 2023 08:16:48 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; 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=pgb2cGtRy6NJQivMZxkD79cF6GM0vBckpsl09sZbJQM=; b=GtixR3arzlIUnN+MRUtIl7LulW TiLyidJERPAaL7c5Mh6GneFkAPNYE/0LD7qOlA4D2IKsGc3z2SrhmO5uWzLxXepeY9ZKK6ic+kM50 z7mp3bqiCUFtv2891vSMrBu6/jbeFHQ07lKjULvcRjLgqvyvu9P8rbjJRBC/IE8kwo26obluaWnpY OV8z/DCyuMkAZrnl3Or7RlPxrgxMNSQl3gmLdB/1MAbUsT7SE2/m3+MBRjmudOwLYS6VwBl/Qf4Lt MihiRQzcdQdFlSxamwFLiJOQ6RG124BVh5VGdAIQ0mgxfg05Wb34PFr7Bg1D3ZL25ZBBKi40aRlN4 jM0UmaQg==; Received: from j130084.upc-j.chello.nl ([24.132.130.84] helo=noisy.programming.kicks-ass.net) by desiato.infradead.org with esmtpsa (Exim 4.96 #2 (Red Hat Linux)) id 1q56W9-001MP5-02; Fri, 02 Jun 2023 15:16:41 +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) server-digest SHA256) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 78825300220; Fri, 2 Jun 2023 17:16:39 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 5F6842058125E; Fri, 2 Jun 2023 17:16:39 +0200 (CEST) Date: Fri, 2 Jun 2023 17:16:39 +0200 From: Peter Zijlstra To: Josh Poimboeuf Cc: Zack Rusin , linux-kernel@vger.kernel.org, Miroslav Benes , x86@kernel.org, VMware Graphics Reviewers , kernel test robot Subject: Re: [PATCH] drm/vmwgfx: Silence RBP clobber warnings Message-ID: <20230602151639.GK620383@hirez.programming.kicks-ass.net> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Spam-Status: No, score=-4.4 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_MED,SPF_HELO_NONE, SPF_NONE,T_SCC_BODY_TEXT_LINE,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jun 02, 2023 at 07:56:34AM -0700, Josh Poimboeuf wrote: > VMware hypercalls take the RBP register as input. This breaks basic > frame pointer convention, as RBP should never be clobbered. > > So frame pointer unwinding is broken for the instructions surrounding > the hypercall with the clobbered RBP. There's nothing that can be done > about that. Just tell objtool to ignore it. > That's a pretty horrific ABI, one that violates the oldest x86 calling convention in existence. VMware folks, shame!!