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=-5.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_NEOMUTT 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 5C087C31E40 for ; Mon, 10 Jun 2019 16:58:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3B16720859 for ; Mon, 10 Jun 2019 16:58:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387740AbfFJQ6W (ORCPT ); Mon, 10 Jun 2019 12:58:22 -0400 Received: from mx1.redhat.com ([209.132.183.28]:39776 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727648AbfFJQ6W (ORCPT ); Mon, 10 Jun 2019 12:58:22 -0400 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id C12E4307D941; Mon, 10 Jun 2019 16:58:04 +0000 (UTC) Received: from treble (ovpn-121-189.rdu2.redhat.com [10.10.121.189]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 28A36600CD; Mon, 10 Jun 2019 16:57:55 +0000 (UTC) Date: Mon, 10 Jun 2019 11:57:52 -0500 From: Josh Poimboeuf To: Peter Zijlstra Cc: x86@kernel.org, linux-kernel@vger.kernel.org, Ard Biesheuvel , Andy Lutomirski , Steven Rostedt , Ingo Molnar , Thomas Gleixner , Linus Torvalds , Masami Hiramatsu , Jason Baron , Jiri Kosina , David Laight , Borislav Petkov , Julia Cartwright , Jessica Yu , "H. Peter Anvin" , Nadav Amit , Rasmus Villemoes , Edward Cree , Daniel Bristot de Oliveira Subject: Re: [PATCH 08/15] x86/alternatives: Teach text_poke_bp() to emulate instructions Message-ID: <20190610165752.2feozekuqbincj3d@treble> References: <20190605130753.327195108@infradead.org> <20190605131945.005681046@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20190605131945.005681046@infradead.org> User-Agent: NeoMutt/20180716 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.48]); Mon, 10 Jun 2019 16:58:21 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jun 05, 2019 at 03:08:01PM +0200, Peter Zijlstra wrote: > In preparation for static_call support, teach text_poke_bp() to > emulate instructions, including CALL. > > The current text_poke_bp() takes a @handler argument which is used as > a jump target when the temporary INT3 is hit by a different CPU. > > When patching CALL instructions, this doesn't work because we'd miss > the PUSH of the return address. Instead, teach poke_int3_handler() to > emulate an instruction, typically the instruction we're patching in. > > This fits almost all text_poke_bp() users, except > arch_unoptimize_kprobe() which restores random text, and for that site > we have to build an explicit emulate instruction. > > Cc: Daniel Bristot de Oliveira > Cc: Nadav Amit > Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Josh Poimboeuf -- Josh