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 X-Spam-Level: X-Spam-Status: No, score=-2.4 required=3.0 tests=DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,T_DKIM_INVALID, USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D6290C46464 for ; Tue, 14 Aug 2018 13:35:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8ABD321655 for ; Tue, 14 Aug 2018 13:35:56 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="JRGFObfe" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8ABD321655 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732860AbeHNQXG (ORCPT ); Tue, 14 Aug 2018 12:23:06 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:58054 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732782AbeHNQXG (ORCPT ); Tue, 14 Aug 2018 12:23:06 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.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:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=xrP27v37wEfLTaarlipron8WUIcSnnq+qIHgp4mVPSM=; b=JRGFObfeQlY972/ReD1H+yBBh hJwe2F1E7Wj8YYo3DFZ1Q6bTpI5kQKM2v3JCojTQEUdn+/QtRDfWssaPbRW8bkqmAP03u2mGXL4yr viW7WRKvL/JN/w58ggT8Uee8RHLuGpAz47YVlEoermTzLMXUPhtozbhLuy/+BBfloBfkBdpVyqrNC RE97C+Bvu43wU9fm+T0497fs5LaWJSBVA0Pm/7TaFgfV8YEsaVC8h4PzldxB+0blXuE+11IZHlNyl q9M5f7FaKaQiJhbpC3C5/wxvHHIVF6oQ8Q50nolcrtbrCz/Rm3THBWVFGd+rU9DouIOLqYVKNdzZy Fv5DQ8bpA==; Received: from hch by bombadil.infradead.org with local (Exim 4.90_1 #2 (Red Hat Linux)) id 1fpZU1-0001vk-2T; Tue, 14 Aug 2018 13:35:38 +0000 Date: Tue, 14 Aug 2018 06:35:36 -0700 From: Christoph Hellwig To: Palmer Dabbelt Cc: Christoph Hellwig , aou@eecs.berkeley.edu, Andrew Waterman , Arnd Bergmann , linux-kernel@vger.kernel.org, linux@dominikbrodowski.net, linux@roeck-us.net, tklauser@distanz.ch, linux-riscv@lists.infradead.org, dan.carpenter@oracle.com Subject: Re: [PATCH v3 1/2] RISC-V: Define sys_riscv_flush_icache when SMP=n Message-ID: <20180814133536.GB28080@infradead.org> References: <20180810083804.GA20415@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.9.2 (2017-12-15) X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Aug 10, 2018 at 11:27:37AM -0700, Palmer Dabbelt wrote: > I'm not sure. We can implement the syscall fine in !SMP, it's just that the > vDSO is expected to always eat these calls because in non-SMP mode you can > do a global fence.i by just doing a local fence.i (there's only one hart). > > The original rationale behind not having the syscall in non-SMP mode was to > limit the user ABI, but on looking again that seems like it's just a bit of > extra complexity that doesn't help anything. It's already been demonstrated > that nothing is checking the error because it's been silently slipping past > userspace for six months, so the extra complexity seems like it'll just > cause someone else to have to chase the bug in the future. > > But I'm really OK either way. Is there a precedent for what to do here? I don't know of any.