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=-4.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_PASS 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 AD04EC282C4 for ; Thu, 7 Feb 2019 17:01:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8460F21904 for ; Thu, 7 Feb 2019 17:01:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727299AbfBGRB1 (ORCPT ); Thu, 7 Feb 2019 12:01:27 -0500 Received: from mail-qt1-f196.google.com ([209.85.160.196]:43416 "EHLO mail-qt1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727268AbfBGRBY (ORCPT ); Thu, 7 Feb 2019 12:01:24 -0500 Received: by mail-qt1-f196.google.com with SMTP id y4so613953qtc.10 for ; Thu, 07 Feb 2019 09:01:23 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=IIQVg0/54aHNSuas4/Tru3avab4Ag3l4H/PDl5CjyJY=; b=rlVBS5BUQgXuSzuuZlHW5oDnWOnCqVvybbRprcXsbUk5o1al8Mrp1LeT5TZ+l26Fak tQ2Ik4XXRWgtOEr2NTSQsUW6JQq2z/LHt8VrHj10NhcRZkqJlvKUXUIoW4YBdU1vE8EW j1bh6z7cAV7u9rcMq4AF6O13qlC5w/HSJFQxLIfFgf6IOjB4dlUIwN7eCSN4wV7UHJkM bM6s5ooPcPMA4BR/+ucCqTtuQf49fuPHf9Z14THFkwBegzg0C4cNnGUTSS+Wy7ZLUkkT e6SLydIDJZR/2GwTk/KHYrTsKIInM5AXckFt6cbO1Pd2ZMI5/z694NKqj4faGqufe4hv MbMw== X-Gm-Message-State: AHQUAuZkgPFNkzStE+v9jgZ11BQAAfzsHukqsNHsphz5gzpXwqkTSl5z /wtKU3LpoiBYPD8i7eVrgzjggRuVksqdRA== X-Google-Smtp-Source: AHgI3IaMpbxB1PIhg95K+sp2Vjj65sg8dUr2oCY6U4Prj8z9irHL0x7REPC27HG3vTH6PinkHiGGag== X-Received: by 2002:aed:31c5:: with SMTP id 63mr12716789qth.385.1549558882260; Thu, 07 Feb 2019 09:01:22 -0800 (PST) Received: from t460s.bristot.redhat.com ([177.72.25.22]) by smtp.gmail.com with ESMTPSA id 10sm11914810qtx.60.2019.02.07.09.01.05 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 07 Feb 2019 09:01:21 -0800 (PST) Subject: Re: [PATCH V4 2/9] jump_label: Add the jump_label_can_update_check() helper To: Borislav Petkov Cc: linux-kernel@vger.kernel.org, Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , Greg Kroah-Hartman , Masami Hiramatsu , "Steven Rostedt (VMware)" , Jiri Kosina , Josh Poimboeuf , "Peter Zijlstra (Intel)" , Chris von Recklinghausen , Jason Baron , Scott Wood , Marcelo Tosatti , Clark Williams , x86@kernel.org References: <36237a0ee38d6c98d080d3fee2921501d8788e4d.1549308412.git.bristot@redhat.com> <20190205072220.GD21801@zn.tnic> <20190205211348.GV21801@zn.tnic> <30b5ffc9-9794-874b-1544-d05034b55f1b@redhat.com> <20190207140819.GF2414@zn.tnic> From: Daniel Bristot de Oliveira Message-ID: <473c03b3-c5c3-7412-e2ad-3dedb413d165@redhat.com> Date: Thu, 7 Feb 2019 18:00:53 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.4.0 MIME-Version: 1.0 In-Reply-To: <20190207140819.GF2414@zn.tnic> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2/7/19 3:08 PM, Borislav Petkov wrote: > On Thu, Feb 07, 2019 at 02:21:09PM +0100, Daniel Bristot de Oliveira wrote: >> diff --git a/kernel/jump_label.c b/kernel/jump_label.c >> index 288d630da22d..1e6f4d27e28d 100644 >> --- a/kernel/jump_label.c >> +++ b/kernel/jump_label.c >> @@ -374,22 +374,29 @@ static enum jump_label_type jump_label_type(struct jump_entry *entry) >> return enabled ^ branch; >> } >> >> +static bool jump_label_can_update(struct jump_entry *entry, bool init) >> +{ >> + /* >> + * Cannot update code that was in an init text area. >> + */ >> + if (!init || jump_entry_is_init(entry)) > > Shouldn't this be && > > ? Oops! should be &&! sorry. >> + return false; >> + >> + if (WARN_ONCE(!kernel_text_address(jump_entry_code(entry)), >> + "can't patch jump_label at %pS", (void *)jump_entry_code(entry))) >> + return false; > > Yeah, I think that this way of writing it is less readable than: > > if (!kernel_text_address(jump_entry_code(entry))) { > WARN_ONCE(1, "can't patch jump_label at %pS", (void *)jump_entry_code(entry)); > return false; > } It is taking 95 characters. In this case, wouldn't be better to break? if (!kernel_text_address(jump_entry_code(entry))) { WARN_ONCE(1, "can't patch jump_label at %pS", (void *)jump_entry_code(entry)); return false; } I agree your suggestion is better... just confirming that 95 is not too long... > >> + if (jump_label_can_update(entry, init)) { >> + arch_jump_label_transform(entry, jump_label_type(entry)); > > Yap. > > Thx. > Thanks! -- Daniel