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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9CD9AC05027 for ; Wed, 8 Feb 2023 21:02:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231344AbjBHVCV (ORCPT ); Wed, 8 Feb 2023 16:02:21 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37018 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231527AbjBHVCS (ORCPT ); Wed, 8 Feb 2023 16:02:18 -0500 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 730294C6F5 for ; Wed, 8 Feb 2023 13:01:32 -0800 (PST) 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=JyTei5zpK8ApzCKRu7QoHZ4mObsZ47vMw3jzATgftIs=; b=dy9Vl6+wUpEsXjTv/0b8bbhkKo +HPC0EdhdNsvTJQJ2LOON3AYQWBWwYJxazPIOXdri+VEl6syQ6OvNSJEZwsbz15bPisZFlB2Jqh/k kar3T7La6bku7d7JuXVgU9hkJStLbSE7xEicgZ+pnPrdSK9TkP5xBUzXVI4/yRPczSy/r22HWDDTI sSW9z+GsVFMSKw+eCV0qsZiITVK42X+iW67PCly3fEERLrHhVdqcmQub2lXfofBfDR8Fd1S1gjO3g gEXleHzCHzBJEsmm4jIX5j3EM9cRAO3EWQ1zIGu1SMXDmogH4Pfh8xp1OAXFBLJU4aUsjqjY5WE5t CSodS9XA==; 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 1pPrYP-007aoQ-24; Wed, 08 Feb 2023 21:00:34 +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)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 709A6300129; Wed, 8 Feb 2023 22:01:11 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 4DA38209BAB68; Wed, 8 Feb 2023 22:01:11 +0100 (CET) Date: Wed, 8 Feb 2023 22:01:11 +0100 From: Peter Zijlstra To: Andrew.Cooper3@citrix.com Cc: x86@kernel.org, linux-kernel@vger.kernel.org, mhiramat@kernel.org, kirill.shutemov@linux.intel.com, jpoimboe@redhat.com Subject: Re: [PATCH v3 3/4] x86/alternative: Rewrite optimize_nops() some Message-ID: References: <20230208171050.490809180@infradead.org> <20230208171431.373412974@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Feb 08, 2023 at 09:44:04PM +0100, Peter Zijlstra wrote: > Works as advertised. Next up are 8 12 byte nopes and 8 13 byte nops, > after that we're left with: Yeah, we can ignore those, those are the retpoline thunks being patched. They should be totally unused. These NOPs are after an indirect jmp and as such pure speculation food. Arguably I should just merge that patch that turns them into UD2 -- funneling and all that. But there was some i386 issues... oh well.