From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752768Ab3KNEHq (ORCPT ); Wed, 13 Nov 2013 23:07:46 -0500 Received: from mail7.hitachi.co.jp ([133.145.228.42]:54468 "EHLO mail7.hitachi.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751372Ab3KNEHi (ORCPT ); Wed, 13 Nov 2013 23:07:38 -0500 Message-ID: <52844C87.1040908@hitachi.com> Date: Thu, 14 Nov 2013 13:07:35 +0900 From: Masami Hiramatsu Organization: Hitachi, Ltd., Japan User-Agent: Mozilla/5.0 (Windows NT 5.2; rv:13.0) Gecko/20120614 Thunderbird/13.0.1 MIME-Version: 1.0 To: Steven Rostedt Cc: LKML , "H. Peter Anvin" , Ingo Molnar , Thomas Gleixner , Andrew Morton Subject: Re: [PATCH v2] ftrace/x86: Load ftrace_ops in parameter not the variable holding it References: <20131113152004.459787f9@gandalf.local.home> In-Reply-To: <20131113152004.459787f9@gandalf.local.home> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org (2013/11/14 5:20), Steven Rostedt wrote: > > Function tracing callbacks expect to have the ftrace_ops that registered it > passed to them, not the address of the variable that holds the ftrace_ops > that registered it. > > Use a mov instead of a lea to store the ftrace_ops into the parameter > of the function tracing callback. I see, function_trace_op is just a pointer to an actual ftrace_ops. :) And I have ensured this change doesn't affect ftrace-kprobes since it doesn't use this parameter. > Signed-off-by: Steven Rostedt Reviewed-by: Masami Hiramatsu Thank you, > --- > arch/x86/kernel/entry_32.S | 4 ++-- > arch/x86/kernel/entry_64.S | 2 +- > 2 files changed, 3 insertions(+), 3 deletions(-) > > diff --git a/arch/x86/kernel/entry_32.S b/arch/x86/kernel/entry_32.S > index f0dcb0c..15a569a 100644 > --- a/arch/x86/kernel/entry_32.S > +++ b/arch/x86/kernel/entry_32.S > @@ -1085,7 +1085,7 @@ ENTRY(ftrace_caller) > pushl $0 /* Pass NULL as regs pointer */ > movl 4*4(%esp), %eax > movl 0x4(%ebp), %edx > - leal function_trace_op, %ecx > + movl function_trace_op, %ecx > subl $MCOUNT_INSN_SIZE, %eax > > .globl ftrace_call > @@ -1143,7 +1143,7 @@ ENTRY(ftrace_regs_caller) > movl 12*4(%esp), %eax /* Load ip (1st parameter) */ > subl $MCOUNT_INSN_SIZE, %eax /* Adjust ip */ > movl 0x4(%ebp), %edx /* Load parent ip (2nd parameter) */ > - leal function_trace_op, %ecx /* Save ftrace_pos in 3rd parameter */ > + movl function_trace_op, %ecx /* Save ftrace_pos in 3rd parameter */ > pushl %esp /* Save pt_regs as 4th parameter */ > > GLOBAL(ftrace_regs_call) > diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S > index b077f4c..9ce2567 100644 > --- a/arch/x86/kernel/entry_64.S > +++ b/arch/x86/kernel/entry_64.S > @@ -88,7 +88,7 @@ END(function_hook) > MCOUNT_SAVE_FRAME \skip > > /* Load the ftrace_ops into the 3rd parameter */ > - leaq function_trace_op, %rdx > + movq function_trace_op(%rip), %rdx > > /* Load ip into the first parameter */ > movq RIP(%rsp), %rdi > -- Masami HIRAMATSU IT Management Research Dept. Linux Technology Center Hitachi, Ltd., Yokohama Research Laboratory E-mail: masami.hiramatsu.pt@hitachi.com