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=-1.0 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,MIME_QP_LONG_LINE, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 598E6C433DF for ; Thu, 2 Jul 2020 03:08:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 30EFB207D4 for ; Thu, 2 Jul 2020 03:08:41 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=amacapital-net.20150623.gappssmtp.com header.i=@amacapital-net.20150623.gappssmtp.com header.b="HJNGE/iV" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726474AbgGBDIk (ORCPT ); Wed, 1 Jul 2020 23:08:40 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55276 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726094AbgGBDIj (ORCPT ); Wed, 1 Jul 2020 23:08:39 -0400 Received: from mail-pf1-x434.google.com (mail-pf1-x434.google.com [IPv6:2607:f8b0:4864:20::434]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4F4DCC08C5C1 for ; Wed, 1 Jul 2020 20:08:39 -0700 (PDT) Received: by mail-pf1-x434.google.com with SMTP id q17so11876592pfu.8 for ; Wed, 01 Jul 2020 20:08:39 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amacapital-net.20150623.gappssmtp.com; s=20150623; h=content-transfer-encoding:from:mime-version:subject:date:message-id :references:cc:in-reply-to:to; bh=nX4jifuVUD4wv3dvKuEbLJYR6Iy5QHbia6zFZRrUfLQ=; b=HJNGE/iVrjl41L5e3nwu2leRVLp42WbAHGKCOLTJAGMERTEKWvoWlDbYd/4qLu1Kn3 48+pcDPNyOPN6QsHJUv8RglMc8NMmNr+JGmMfpy37riOe4M5EwihMAq7gV9IqTnUcUjD i2wW6wT7Wb1zipA65eOzxw1YiVPX55yhPtuP696VjAQtUuqZLlyb04CtaxTQC2nPJOEB jwU/YMwB9qWDY6reG9BnbEDMC3NN6TM1sKyOuP38yy6NfnDl3dNwu4os2d9lLxUcLEZ9 5EZbUbonPixPnHPCQDn8rEV44OVmwZAla3RDqE1r2UrS/3e1F9OuDWT0G2rN+PP1u2H0 O4PA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:content-transfer-encoding:from:mime-version :subject:date:message-id:references:cc:in-reply-to:to; bh=nX4jifuVUD4wv3dvKuEbLJYR6Iy5QHbia6zFZRrUfLQ=; b=FF7GENmWWyRnjg9xiRFCNc9fD69vohO7CClTyYydmIs0V7R2H9iHC3bjkDdnYXblbP vgZ4lx83TKLvvZUk9pVTdM6sunW6zZS3XPegWPrxbEZK+NjW3hzteXFOwgeGB0GJLYZq OtCcnY177B9fO3aET4I/dsTFuRPeSdYj6Itwo36xXVYsyz0EOXFUcWbtsCyO96xNC+el Gy92W9Uedq3RZaPd5QxS0pJeuBSzMkQqGVQDJmhZ5b5gRCOWtk/TB8MOmmjIxqo8Tmlv O9sehqcUDLEVazt9IKB3KA2mkvLVS44b9oCXbLkb9BBZWHNQDwVJ5jBDJ70gL5TG7TyJ 0g7g== X-Gm-Message-State: AOAM533rYHZhmlqPEqbEGqKVyCHimKsCmRgzzcemG/O3JqAuvr/QoL2K vsS8VrMlzCyAPCCtD7wKZe1vmg== X-Google-Smtp-Source: ABdhPJzGryBl1zzI9Sjl18IeYrLO+6//97HpZ6bzh7J6TtqubS+bIb1s9tn4ZXWr5IovpoA6bHRoiQ== X-Received: by 2002:a65:63ca:: with SMTP id n10mr23100362pgv.252.1593659318743; Wed, 01 Jul 2020 20:08:38 -0700 (PDT) Received: from ?IPv6:2601:646:c200:1ef2:acd6:6304:8edb:f3fc? ([2601:646:c200:1ef2:acd6:6304:8edb:f3fc]) by smtp.gmail.com with ESMTPSA id 73sm7333278pfy.24.2020.07.01.20.08.37 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 01 Jul 2020 20:08:37 -0700 (PDT) Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable From: Andy Lutomirski Mime-Version: 1.0 (1.0) Subject: Re: objtool clac/stac handling change.. Date: Wed, 1 Jul 2020 20:08:36 -0700 Message-Id: References: Cc: Andy Lutomirski , Josh Poimboeuf , Peter Zijlstra , the arch/x86 maintainers , Linux Kernel Mailing List In-Reply-To: To: Linus Torvalds X-Mailer: iPhone Mail (17F80) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > On Jul 1, 2020, at 7:30 PM, Linus Torvalds = wrote: >=20 > =EF=BB=BFOn Wed, Jul 1, 2020 at 5:48 PM Andy Lutomirski w= rote: >>=20 >> You inspired me to mock it up. >=20 > Ahh, you want to just use the jump folding of gcc to avoid the problem. >=20 > I guess we could do that. Are there cases where this actually helps? >=20 I was thinking it would help avoid brain melt. For better or for worse, the k= ernel is written in C, and readers don=E2=80=99t really expect call_some_fun= ction(arg, other arg) to actually teleport elsewhere in the function. I=E2=80= =99m all for goto err; but at least that=E2=80=99s spelled =E2=80=9Cgoto=E2=80= =9D and it=E2=80=99s really obvious what it does.=