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=-5.0 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 EA028CA9EC0 for ; Mon, 28 Oct 2019 16:34:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BB4B220717 for ; Mon, 28 Oct 2019 16:34:53 +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="GCLVOBm/" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1733114AbfJ1Qew (ORCPT ); Mon, 28 Oct 2019 12:34:52 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:54698 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729420AbfJ1Qew (ORCPT ); Mon, 28 Oct 2019 12:34:52 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.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:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=+PJ/cpShLksxhXNNFQzNtVO1Gbe6G/ZmOiI95RIQce8=; b=GCLVOBm/AQ5lGmzipioJfLuii NJIAO+hNF72A3wMGAYq+jfA+4lyjSUzTMNyZuDrJvjjlNhEup02/qtXEib006wQfw1GNe9qAnhWLG T1CetWl1qhf9gUa67j0CWOua8ErGUPSlVApNsPYaaBp4bp8r2qp2nK1nvJe9z1a2gB7TN62XXPk1m eMy6SHnjhQZNoxfB+Yoq4JNTzeYu0aXZtYDOKxG2ruBlOOakyr5VB4i+k1PK6rNRSO/wJ+sRdGSIw rcYxAJbdzBYjG4EQzMwv3zBAQTsOciEZOJVxmGtqvDnutDhVpoSgmAajpwf+D6hEDCQRS+bbmOl1C LIk8Blh+g==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by bombadil.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1iP7yK-0007uC-JH; Mon, 28 Oct 2019 16:34:25 +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 90DC23002B0; Mon, 28 Oct 2019 17:33:21 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id E173020C4EA0B; Mon, 28 Oct 2019 17:34:21 +0100 (CET) Date: Mon, 28 Oct 2019 17:34:21 +0100 From: Peter Zijlstra To: Will Deacon Cc: x86@kernel.org, linux-kernel@vger.kernel.org, rostedt@goodmis.org, mhiramat@kernel.org, bristot@redhat.com, jbaron@akamai.com, torvalds@linux-foundation.org, tglx@linutronix.de, mingo@kernel.org, namit@vmware.com, hpa@zytor.com, luto@kernel.org, ard.biesheuvel@linaro.org, jpoimboe@redhat.com, jeyu@kernel.org, rabin@rab.in, Mark Rutland , james.morse@arm.com Subject: Re: [PATCH v4 13/16] arm/ftrace: Use __patch_text_real() Message-ID: <20191028163421.GI4097@hirez.programming.kicks-ass.net> References: <20191018073525.768931536@infradead.org> <20191018074634.687479693@infradead.org> <20191028162525.GF5576@willie-the-truck> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191028162525.GF5576@willie-the-truck> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Oct 28, 2019 at 04:25:26PM +0000, Will Deacon wrote: > Hi Peter, > > On Fri, Oct 18, 2019 at 09:35:38AM +0200, Peter Zijlstra wrote: > > Instead of flipping text protection, use the patch_text infrastructure > > that uses a fixmap alias where required. > > > > This removes the last user of set_all_modules_text_*(). > > > > Signed-off-by: Peter Zijlstra (Intel) > > Cc: ard.biesheuvel@linaro.org > > Cc: rabin@rab.in > > Cc: Mark Rutland > > Cc: Will Deacon > > Cc: james.morse@arm.com > > --- > > arch/arm/kernel/ftrace.c | 16 ++++++++-------- > > 1 file changed, 8 insertions(+), 8 deletions(-) > > > > --- a/arch/arm/kernel/ftrace.c > > +++ b/arch/arm/kernel/ftrace.c > > @@ -22,6 +22,7 @@ > > #include > > #include > > #include > > +#include > > > > #ifdef CONFIG_THUMB2_KERNEL > > #define NOP 0xf85deb04 /* pop.w {lr} */ > > @@ -31,13 +32,15 @@ > > > > #ifdef CONFIG_DYNAMIC_FTRACE > > > > +static int patch_text_remap = 0; > > + > > static int __ftrace_modify_code(void *data) > > { > > int *command = data; > > > > - set_kernel_text_rw(); > > + patch_text_remap++; > > ftrace_modify_all_code(*command); > > - set_kernel_text_ro(); > > + patch_text_remap--; > > > > return 0; > > } > > @@ -59,13 +62,13 @@ static unsigned long adjust_address(stru > > > > int ftrace_arch_code_modify_prepare(void) > > { > > - set_all_modules_text_rw(); > > + patch_text_remap++; > > return 0; > > } > > > > int ftrace_arch_code_modify_post_process(void) > > { > > - set_all_modules_text_ro(); > > + patch_text_remap--; > > /* Make sure any TLB misses during machine stop are cleared. */ > > flush_tlb_all(); > > return 0; > > @@ -97,10 +100,7 @@ static int ftrace_modify_code(unsigned l > > return -EINVAL; > > } > > > > - if (probe_kernel_write((void *)pc, &new, MCOUNT_INSN_SIZE)) > > - return -EPERM; > > - > > - flush_icache_range(pc, pc + MCOUNT_INSN_SIZE); > > + __patch_text_real((void *)pc, new, patch_text_remap); > > Why can't you just pass 'true' for patch_text_remap? AFAICT, the only > time you want to pass false is during early boot when the text is > assumedly still writable without the fixmap. Ah, it will also become true for module loading once we rework where we flip the module text RO,X. See this patch: https://lkml.kernel.org/r/20191018074634.858645375@infradead.org But for that to land, there's still a few other issues to fix (KLP).