Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756561Ab3H3RDe (ORCPT ); Fri, 30 Aug 2013 13:03:34 -0400 Received: from hrndva-omtalb.mail.rr.com ([71.74.56.122]:23592 "EHLO hrndva-omtalb.mail.rr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753508Ab3H3RDd (ORCPT ); Fri, 30 Aug 2013 13:03:33 -0400 X-Authority-Analysis: v=2.0 cv=V4T/IJbi c=1 sm=0 a=Sro2XwOs0tJUSHxCKfOySw==:17 a=Drc5e87SC40A:10 a=JDI8IL8UnGoA:10 a=5SG0PmZfjMsA:10 a=kj9zAlcOel0A:10 a=meVymXHHAAAA:8 a=KGjhK52YXX0A:10 a=BKUXQ1-ENX0A:10 a=oGMlB6cnAAAA:8 a=xtpnuDK__jDR5YpMp14A:9 a=CjuIK1q_8ugA:10 a=CY6gl2JlH4YA:10 a=Sro2XwOs0tJUSHxCKfOySw==:117 X-Cloudmark-Score: 0 X-Authenticated-User: X-Originating-IP: 67.255.60.225 Date: Fri, 30 Aug 2013 13:03:31 -0400 From: Steven Rostedt To: "H. Peter Anvin" Cc: Jan Kiszka , Fenghua Yu , Linux Kernel Mailing List , x86 , Ingo Molnar , Thomas Gleixner Subject: Re: x86-32: Early microcode loading stumbles over disabled DYNAMIC_FTRACE Message-ID: <20130830130331.1e260e85@gandalf.local.home> In-Reply-To: <5220C9C6.5020808@zytor.com> References: <5217908E.2040702@siemens.com> <5220BC1A.3030108@zytor.com> <20130830115142.1ee4c825@gandalf.local.home> <5220C9C6.5020808@zytor.com> X-Mailer: Claws Mail 3.9.2 (GTK+ 2.24.20; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1022 Lines: 29 On Fri, 30 Aug 2013 09:35:18 -0700 "H. Peter Anvin" wrote: > On 08/30/2013 08:51 AM, Steven Rostedt wrote: > > > > It does when dynamic tracing is enabled. But this issue is with static > > tracing, there's no code modification, thus all functions call > > mcount/__fentry__ and we need to look at a variable to determine if we > > should trace or not. > > > > And of course global variables are a no-no without special handling in > pre-paging mode. Sigh. > > You *could* bail out of the calling address is < PAGE_OFFSET. > We could do that too, as static tracing already gives us high overhead, I'm not sure how much more overhead another check like this even matters. Who uses static tracing? I only use it to test that it still works ;-) -- Steve -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/