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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 5700BC7EE43 for ; Sat, 10 Jun 2023 19:51:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:In-Reply-To:References: Message-ID:Date:Subject:CC:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=oTwFJrCkllTdgkkr4cUtvWaSJ44INY0Tj7a7jnrVUA0=; b=gpv6MQcBc5oj3k sC9pKB4GKVq3H/HS8M8/0kt/3NHxPcYYvrKdJhKrsG47nEh43jMCvEhE5OGbLmeVDbrK+3HNxxbgV mGQ4vFVC3c6a1wesGhoN0A06DLq0lIu1+FwJtGA+f5ghU726R6rQwPHxgddDrkp5o1pwcrT4JbrYA UrT6W/dPN14ZlcqzyQrmqOxvBqS1IeJgt7UsCuhyEjHliJuSCDLH6jQOtpRCDCpBB6J/u6OyLN2Tr /C//p5uVIgEhndizYiYVGq6wzmof89fFICkbZjiFjPXk3sdLydikNJwcO64xxq5l4hIknMxTp8yi7 S2DNl7oRuJQ4ZF2FdtcQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1q84cG-00Gvd4-0g; Sat, 10 Jun 2023 19:51:16 +0000 Received: from eu-smtp-delivery-151.mimecast.com ([185.58.86.151]) by bombadil.infradead.org with esmtps (Exim 4.96 #2 (Red Hat Linux)) id 1q84cB-00Gval-2C for linux-riscv@lists.infradead.org; Sat, 10 Jun 2023 19:51:13 +0000 Received: from AcuMS.aculab.com (156.67.243.121 [156.67.243.121]) by relay.mimecast.com with ESMTP with both STARTTLS and AUTH (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384) id uk-mta-191-aQsr8P1pPA2zGT4voRzmug-1; Sat, 10 Jun 2023 20:51:04 +0100 X-MC-Unique: aQsr8P1pPA2zGT4voRzmug-1 Received: from AcuMS.Aculab.com (10.202.163.6) by AcuMS.aculab.com (10.202.163.6) with Microsoft SMTP Server (TLS) id 15.0.1497.48; Sat, 10 Jun 2023 20:50:58 +0100 Received: from AcuMS.Aculab.com ([::1]) by AcuMS.aculab.com ([::1]) with mapi id 15.00.1497.048; Sat, 10 Jun 2023 20:50:58 +0100 From: David Laight To: 'Andrew Cooper' , Yunhong Jiang , Thomas Gleixner CC: "Kirill A. Shutemov" , LKML , "x86@kernel.org" , "David Woodhouse" , Brian Gerst , "Arjan van de Veen" , Paolo Bonzini , "Paul McKenney" , Tom Lendacky , "Sean Christopherson" , Oleksandr Natalenko , Paul Menzel , "Guilherme G. Piccoli" , Piotr Gorski , Usama Arif , Juergen Gross , "Boris Ostrovsky" , "xen-devel@lists.xenproject.org" , Russell King , "Arnd Bergmann" , "linux-arm-kernel@lists.infradead.org" , Catalin Marinas , Will Deacon , Guo Ren , "linux-csky@vger.kernel.org" , Thomas Bogendoerfer , "linux-mips@vger.kernel.org" , "James E.J. Bottomley" , Helge Deller , "linux-parisc@vger.kernel.org" , Paul Walmsley , Palmer Dabbelt , "linux-riscv@lists.infradead.org" , "Mark Rutland" , Sabin Rapan , "Michael Kelley (LINUX)" , Dave Hansen Subject: RE: [patch] x86/realmode: Make stack lock work in trampoline_compat() Thread-Topic: [patch] x86/realmode: Make stack lock work in trampoline_compat() Thread-Index: AQHZmmUgtDGga6k1FUelCeu8f3dcaq+Ecr5A Date: Sat, 10 Jun 2023 19:50:58 +0000 Message-ID: <67f939e112cc4578833ca74123bee402@AcuMS.aculab.com> References: <20230508181633.089804905@linutronix.de> <20230508185218.962208640@linutronix.de> <20230524204818.3tjlwah2euncxzmh@box.shutemov.name> <87y1lbl7r6.ffs@tglx> <87sfbhlwp9.ffs@tglx> <20230529023939.mc2akptpxcg3eh2f@box.shutemov.name> <87bki3kkfi.ffs@tglx> <20230529203129.sthnhzgds7ynddxd@box.shutemov.name> <87h6rujdvl.ffs@tglx> <20230608233402.GA3430@yjiang5-mobl.amr.corp.intel.com> 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 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-20230610_125112_062973_4F583E54 X-CRM114-Status: UNSURE ( 8.35 ) X-CRM114-Notice: Please train this message. X-BeenThere: linux-riscv@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-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org From: Andrew Cooper > Sent: 09 June 2023 00:58 > ... > The important point is the l suffix on btsl, which forces it to be long > (32bit) irrespective of the default operand size. Does that matter at all? The 'bit' opcodes (I'm sure 'bts' is 'bit test and set') take a bit offset from the base address. This accesses the same bit regardless of the operand size. The one real issue is that a byte operand will only lock the one byte. This might be problematic if non-bit locked accesses are also used. Although it would need to be rather obscure use. (This may be one of them...) The only other problem is that btsl always does a locked 32bit access. If the base address is misaligned this is a misaligned locked access - problematic if it crosses a cache line boundary. David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales) _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv