From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752118AbcEOVlI (ORCPT ); Sun, 15 May 2016 17:41:08 -0400 Received: from mail-wm0-f46.google.com ([74.125.82.46]:36386 "EHLO mail-wm0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750843AbcEOVlF (ORCPT ); Sun, 15 May 2016 17:41:05 -0400 Date: Sun, 15 May 2016 22:41:01 +0100 From: Matt Fleming To: Steven Rostedt Cc: Namhyung Kim , LKML , Ingo Molnar , x86@kernel.org, Borislav Petkov Subject: Re: [PATCH] ftrace/x86: Fix function graph tracer reset path Message-ID: <20160515214101.GA6574@codeblueprint.co.uk> References: <1463147623-2575-1-git-send-email-namhyung@kernel.org> <20160513100610.1a90ea6f@gandalf.local.home> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160513100610.1a90ea6f@gandalf.local.home> User-Agent: Mutt/1.5.24+41 (02bc14ed1569) (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 13 May, at 10:06:10AM, Steven Rostedt wrote: > Matt, > > This bug looks very similar to what you were hitting with the function > profiler. Can you apply this patch and see if it fixes the issue for > you. Yep, this patch fixes it for me. For the record, this is what objdump tells me (with patch applied), 00000000000000b6 : b6: eb 03 jmp bb b8: 90 nop b9: 90 nop ba: 90 nop So my toolchain is definitely generating a short jump. This is binutils 2.26. But on one of my other test machines with binutils 2.24 I see this, 00000000000000aa : aa: e9 00 00 00 00 jmpq af ab: R_X86_64_PC32 ftrace_stub-0x4 i.e. a near jump.