From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756236AbaKSS3a (ORCPT ); Wed, 19 Nov 2014 13:29:30 -0500 Received: from www.linutronix.de ([62.245.132.108]:46858 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752315AbaKSS33 (ORCPT ); Wed, 19 Nov 2014 13:29:29 -0500 Date: Wed, 19 Nov 2014 19:29:25 +0100 (CET) From: Thomas Gleixner To: Steven Rostedt cc: Namhyung Kim , linux-kernel@vger.kernel.org, Ingo Molnar , Andrew Morton , "H. Peter Anvin" , williams@redhat.com, Masami Hiramatsu , Ingo Molnar Subject: Re: [PATCH 2/2] ftrace/x86/extable: Add is_ftrace_trampoline() function In-Reply-To: <20141119103716.1aa83ac3@gandalf.local.home> Message-ID: References: <20141119033331.689278545@goodmis.org> <20141119034829.497125839@goodmis.org> <87mw7nppu0.fsf@sejong.aot.lge.com> <20141119103716.1aa83ac3@gandalf.local.home> User-Agent: Alpine 2.11 (DEB 23 2013-08-11) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001,URIBL_BLOCKED=0.001 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 19 Nov 2014, Steven Rostedt wrote: > From: "Steven Rostedt (Red Hat)" > Date: Tue, 18 Nov 2014 21:14:11 -0500 > Subject: [PATCH] ftrace/x86/extable: Add is_ftrace_trampoline() function > > Stack traces that happen from function tracing check if the address > on the stack is a __kernel_text_address(). That is, is the address > kernel code. This calls core_kernel_text() which returns true > if the address is part of the builtin kernel code. It also calls > is_module_text_address() which returns true if the address belongs > to module code. > > But what is missing is ftrace dynamically allocated trampolines. > These trampolines are allocated for individual ftrace_ops that > call the ftrace_ops callback functions directly. But if they do a > stack trace, the code checking the stack wont detect them as they > are neither core kernel code nor module address space. > > Adding another field to ftrace_ops that also stores the size of > the trampoline assigned to it we can create a new function called > is_ftrace_trampoline() that returns true if the address is a > dynamically allocate ftrace trampoline. Note, it ignores trampolines > that are not dynamically allocated as they will return true with > the core_kernel_text() function. > > Link: http://lkml.kernel.org/r/20141119034829.497125839@goodmis.org > > Cc: Thomas Gleixner > Cc: Ingo Molnar > Cc: "H. Peter Anvin" > Signed-off-by: Steven Rostedt Acked-by: Thomas Gleixner