From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eu-smtp-delivery-151.mimecast.com (eu-smtp-delivery-151.mimecast.com [185.58.86.151]) (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 741D97F for ; Tue, 17 May 2022 07:56:09 +0000 (UTC) Received: from AcuMS.aculab.com (156.67.243.121 [156.67.243.121]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384) id uk-mta-89-AbgIZabJO0GTyUNJIXZG-Q-1; Tue, 17 May 2022 08:56:06 +0100 X-MC-Unique: AbgIZabJO0GTyUNJIXZG-Q-1 Received: from AcuMS.Aculab.com (fd9f:af1c:a25b:0:994c:f5c2:35d6:9b65) by AcuMS.aculab.com (fd9f:af1c:a25b:0:994c:f5c2:35d6:9b65) with Microsoft SMTP Server (TLS) id 15.0.1497.36; Tue, 17 May 2022 08:56:05 +0100 Received: from AcuMS.Aculab.com ([fe80::994c:f5c2:35d6:9b65]) by AcuMS.aculab.com ([fe80::994c:f5c2:35d6:9b65%12]) with mapi id 15.00.1497.036; Tue, 17 May 2022 08:56:05 +0100 From: David Laight To: 'Sami Tolvanen' , Peter Zijlstra CC: "linux-kernel@vger.kernel.org" , Kees Cook , Josh Poimboeuf , "x86@kernel.org" , Catalin Marinas , Will Deacon , Mark Rutland , "Nathan Chancellor" , Nick Desaulniers , Joao Moreira , Sedat Dilek , Steven Rostedt , "linux-hardening@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "llvm@lists.linux.dev" Subject: RE: [RFC PATCH v2 20/21] x86: Add support for CONFIG_CFI_CLANG Thread-Topic: [RFC PATCH v2 20/21] x86: Add support for CONFIG_CFI_CLANG Thread-Index: AQHYZwdlgt4N7xLw0EK8voqNmmoVIa0hK0vAgAB8yACAAF6CUIAADPZSgACjHQA= Date: Tue, 17 May 2022 07:56:05 +0000 Message-ID: <161477674eb04ebe94a4905070bc9f97@AcuMS.aculab.com> References: <20220513202159.1550547-1-samitolvanen@google.com> <20220513202159.1550547-21-samitolvanen@google.com> <19b3e040302d4d8aa240eee43427dfaa@AcuMS.aculab.com> <20220516214414.GR76023@worktop.programming.kicks-ass.net> In-Reply-To: Accept-Language: en-GB, en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [10.202.205.107] Precedence: bulk X-Mailing-List: llvm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Authentication-Results: relay.mimecast.com; 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Tue, 17 May 2022 07:56:16 +0000 Received: from eu-smtp-delivery-151.mimecast.com ([185.58.86.151]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1nqs3v-00CHS6-7w for linux-arm-kernel@lists.infradead.org; Tue, 17 May 2022 07:56:13 +0000 Received: from AcuMS.aculab.com (156.67.243.121 [156.67.243.121]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384) id uk-mta-89-AbgIZabJO0GTyUNJIXZG-Q-1; Tue, 17 May 2022 08:56:06 +0100 X-MC-Unique: AbgIZabJO0GTyUNJIXZG-Q-1 Received: from AcuMS.Aculab.com (fd9f:af1c:a25b:0:994c:f5c2:35d6:9b65) by AcuMS.aculab.com (fd9f:af1c:a25b:0:994c:f5c2:35d6:9b65) with Microsoft SMTP Server (TLS) id 15.0.1497.36; Tue, 17 May 2022 08:56:05 +0100 Received: from AcuMS.Aculab.com ([fe80::994c:f5c2:35d6:9b65]) by AcuMS.aculab.com ([fe80::994c:f5c2:35d6:9b65%12]) with mapi id 15.00.1497.036; Tue, 17 May 2022 08:56:05 +0100 From: David Laight To: 'Sami Tolvanen' , Peter Zijlstra CC: "linux-kernel@vger.kernel.org" , Kees Cook , Josh Poimboeuf , "x86@kernel.org" , Catalin Marinas , Will Deacon , Mark Rutland , "Nathan Chancellor" , Nick Desaulniers , Joao Moreira , Sedat Dilek , Steven Rostedt , "linux-hardening@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "llvm@lists.linux.dev" Subject: RE: [RFC PATCH v2 20/21] x86: Add support for CONFIG_CFI_CLANG Thread-Topic: [RFC PATCH v2 20/21] x86: Add support for CONFIG_CFI_CLANG Thread-Index: AQHYZwdlgt4N7xLw0EK8voqNmmoVIa0hK0vAgAB8yACAAF6CUIAADPZSgACjHQA= Date: Tue, 17 May 2022 07:56:05 +0000 Message-ID: <161477674eb04ebe94a4905070bc9f97@AcuMS.aculab.com> References: <20220513202159.1550547-1-samitolvanen@google.com> <20220513202159.1550547-21-samitolvanen@google.com> <19b3e040302d4d8aa240eee43427dfaa@AcuMS.aculab.com> <20220516214414.GR76023@worktop.programming.kicks-ass.net> In-Reply-To: Accept-Language: en-GB, en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [10.202.205.107] MIME-Version: 1.0 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=C51A453 smtp.mailfrom=david.laight@aculab.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: aculab.com Content-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220517_005611_620799_1052282C X-CRM114-Status: GOOD ( 16.73 ) 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 From: Sami Tolvanen > Sent: 16 May 2022 23:03 > > On Mon, May 16, 2022 at 2:44 PM Peter Zijlstra wrote: > > > > On Mon, May 16, 2022 at 09:32:55PM +0000, David Laight wrote: > > > > > > The compiler always generates this specific instruction sequence. > > > > > > Yes, but there are several ways to encode 'cmpl imm,-6(reg)'. > > > > Yes, but we don't care. This *always* uses the 32bit immediate form. > > Even if the immediate is small. > > Yes, that part is not a problem, but it's a valid point that LLVM > might not always use r8-r15 here, so I will have to check for the REX > prefix before blindly attempting to decode the instruction. Are you allowing for the REX prefix at all? The encoding of: > > > + * cmpl , -6(%reg) ; 7 bytes is which is 7 bytes without the REX. If reg is r11 there is an extra REX byte - for 8 in total. Without the REX byte the decode will be using %bx. So the testing should all have failed. Which means that something else is wrong as well. David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales) _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel