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=-0.6 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no 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 EC0ECC2BB55 for ; Tue, 7 Apr 2020 14:00:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BCCD720719 for ; Tue, 7 Apr 2020 14:00:03 +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="oM1IEdbc" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729005AbgDGOAD (ORCPT ); Tue, 7 Apr 2020 10:00:03 -0400 Received: from merlin.infradead.org ([205.233.59.134]:54804 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728812AbgDGOAC (ORCPT ); Tue, 7 Apr 2020 10:00:02 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.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=V0PThIqL+3Tnl8qPdklgGnLMHmlP2oR/nQ9+0x/1Wj4=; b=oM1IEdbcAd483e1c2RJR+ky5cR ty7wv+TXVWqYbzZjgar3pbFmVP+f+CecWoHksxAhhAvhP6zPKFySP6rlvYkwa1kSTmGYbOxx4801x uWcN/Gl4cp/PNvTMEB50k2BR1H086CRP8e3v0c/urFTUVLlwrnY3904VCGGgQ98ImwvcncdSf2tzK ++CqtCZk8WQOMpbnZTmjgly457E4/d+WZAB6iWtp55aqufZcaz5kZ1ks421+VYnqQ9aQaKL3s25y2 v+OwCoR+1lmh3VwX4sXsAFUY79RtDnZnL7KYiXcPtCCrqQpgk+cIBBRXksvlX3Durga/mpWZTl7y7 PmeONRyQ==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1jLolg-0001g4-81; Tue, 07 Apr 2020 13:59:56 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 41ECF304D58; Tue, 7 Apr 2020 15:59:53 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 2BC3C2B953CBE; Tue, 7 Apr 2020 15:59:53 +0200 (CEST) Date: Tue, 7 Apr 2020 15:59:53 +0200 From: Peter Zijlstra To: Alexandre Chartre Cc: x86@kernel.org, linux-kernel@vger.kernel.org, jpoimboe@redhat.com, jthierry@redhat.com, tglx@linutronix.de Subject: Re: [PATCH V2 9/9] x86/speculation: Remove all ANNOTATE_NOSPEC_ALTERNATIVE directives Message-ID: <20200407135953.GC20730@hirez.programming.kicks-ass.net> References: <20200407073142.20659-1-alexandre.chartre@oracle.com> <20200407073142.20659-10-alexandre.chartre@oracle.com> <20200407135211.GB20730@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200407135211.GB20730@hirez.programming.kicks-ass.net> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Apr 07, 2020 at 03:52:11PM +0200, Peter Zijlstra wrote: > On Tue, Apr 07, 2020 at 09:31:42AM +0200, Alexandre Chartre wrote: > > > - ANNOTATE_NOSPEC_ALTERNATIVE > > ALTERNATIVE_2 __stringify(ANNOTATE_RETPOLINE_SAFE; jmp *\reg), \ > > __stringify(RETPOLINE_JMP \reg), X86_FEATURE_RETPOLINE, \ > > __stringify(lfence; ANNOTATE_RETPOLINE_SAFE; jmp *\reg), X86_FEATURE_RETPOLINE_AMD > > Possibly we can write this like: .macro OOL_RETPOLINE_JMP reg:req SYM_FUNC_START(__x86_retpoline_jmp_\reg) CFI_STARTPROC RETPOLINE_JMP \reg CFI_ENDPROC SYM_FUNC_END(__x86_retpoline_jmp_\reg) .endm > ALTERNATIVE("", "lfence", X86_FEATURE_RETPOLINE_AMD); > ALTERNATIVE("jmp *\reg", "jmp __x86_retpoline_jmp_\reg", X86_FEATURE_RETPOLINE); > > With an out-of-line copy of the retpoline, just like the THUNKs the > compiler uses, except of course, it can't be those, because we actually > want to use the alternative to implement those. > > By moving the retpoline magic out-of-line we ensure it has a unique > address and the ORC stuff should work. > > I'm just not sure what to do about the RETPOLINE_CALL variant. Duh, something like so: ALTERNATIVE("", "lfence", X86_FEATURE_RETPOLINE_AMD); ALTERNATIVE("call *\reg", "call __x86_retpoline_jmp_\reg", X86_FEATURE_RETPOLINE);