From mboxrd@z Thu Jan 1 00:00:00 1970 Received: with ECARTIS (v1.0.0; list linux-mips); Thu, 18 Jul 2013 22:15:08 +0200 (CEST) Received: from mail-pd0-f177.google.com ([209.85.192.177]:44105 "EHLO mail-pd0-f177.google.com" rhost-flags-OK-OK-OK-OK) by eddie.linux-mips.org with ESMTP id S6819780Ab3GRUPCMAu6b (ORCPT ); Thu, 18 Jul 2013 22:15:02 +0200 Received: by mail-pd0-f177.google.com with SMTP id p10so3439060pdj.36 for ; Thu, 18 Jul 2013 13:14:55 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=message-id:date:from:user-agent:mime-version:to:cc:subject :references:in-reply-to:content-type:content-transfer-encoding; bh=BmHSSlmo4ZjUU+u+rhu7BkmaxwK97h2RJFRi0gVkr3Y=; b=emR7u2cIvUJR2EF5qraTcrqda3HZ+PNymjmxxYXnsRVip+5jbtJ/TY1P//W4vpRhh0 Qz5Vm9u+jHB/OQ/VN6mf5rkX+eTf+SmDIph2cwKeyE5SzPyqkila953Rj6PmorzM0jzh g5/lE1wEsNgMjlGkze0tgXRbEk4HJQZGTzCzHt4dAJbn1ykcoyTVf0kujm3u0kmzE2ox mSrcoE+2bWySZOyN5VkBJI+RjOQj4PT7TCWrc9Fss3hpEht6qrCPgc0CSbW60aWz0muQ MOxl9k6XEKsLQ6vBP3jbyvcyYaxM8M7qXDOb43LSk9otQgSFODqLCjVyYVsyZKZ9ti7U MIiw== X-Received: by 10.66.139.227 with SMTP id rb3mr14866763pab.121.1374178495277; Thu, 18 Jul 2013 13:14:55 -0700 (PDT) Received: from dl.caveonetworks.com (64.2.3.195.ptr.us.xo.net. [64.2.3.195]) by mx.google.com with ESMTPSA id is3sm9173648pbc.25.2013.07.18.13.14.53 for (version=TLSv1 cipher=RC4-SHA bits=128/128); Thu, 18 Jul 2013 13:14:54 -0700 (PDT) Message-ID: <51E84CBC.80206@gmail.com> Date: Thu, 18 Jul 2013 13:14:52 -0700 From: David Daney User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130514 Thunderbird/17.0.6 MIME-Version: 1.0 To: Steven Rostedt CC: linux-mips@linux-mips.org, ralf@linux-mips.org, Corey Minyard , David Daney Subject: Re: [PATCH] mips/ftrace: Fix function tracing return address to match References: <1373926637-24627-1-git-send-email-ddaney.cavm@gmail.com> <1374178262.6458.266.camel@gandalf.local.home> In-Reply-To: <1374178262.6458.266.camel@gandalf.local.home> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Return-Path: X-Envelope-To: <"|/home/ecartis/ecartis -s linux-mips"> (uid 0) X-Orcpt: rfc822;linux-mips@linux-mips.org Original-Recipient: rfc822;linux-mips@linux-mips.org X-archive-position: 37325 X-ecartis-version: Ecartis v1.0.0 Sender: linux-mips-bounce@linux-mips.org Errors-to: linux-mips-bounce@linux-mips.org X-original-sender: ddaney.cavm@gmail.com Precedence: bulk List-help: List-unsubscribe: List-software: Ecartis version 1.0.0 List-Id: linux-mips X-List-ID: linux-mips List-subscribe: List-owner: List-post: List-archive: X-list: linux-mips On 07/18/2013 01:11 PM, Steven Rostedt wrote: > On Mon, 2013-07-15 at 15:17 -0700, David Daney wrote: >> From: Corey Minyard >> >> Dynamic function tracing was not working on MIPS. When doing dynamic >> tracing, the tracer attempts to match up the passed in address with >> the one the compiler creates in the mcount tables. The MIPS code was >> passing in the return address from the tracing function call, but the >> compiler tables were the address of the function call. So they >> wouldn't match. >> >> Just subtracting 8 from the return address will give the address of >> the function call. Easy enough. >> >> Signed-off-by: Corey Minyard >> [david.daney@cavium.com: Adjusted code comment and patch Subject.] >> Signed-off-by: David Daney >> --- >> arch/mips/kernel/mcount.S | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/arch/mips/kernel/mcount.S b/arch/mips/kernel/mcount.S >> index a03e93c..539b629 100644 >> --- a/arch/mips/kernel/mcount.S >> +++ b/arch/mips/kernel/mcount.S >> @@ -83,7 +83,7 @@ _mcount: >> PTR_S MCOUNT_RA_ADDRESS_REG, PT_R12(sp) >> #endif >> >> - move a0, ra /* arg1: self return address */ >> + PTR_SUBU a0, ra, 8 /* arg1: self address */ >> .globl ftrace_call >> ftrace_call: >> nop /* a placeholder for the call to a real tracing function */ > > I applied this patch to my Yeeloong Lemote laptop and it causes the > system to crash. Not sure why. I'll try to investigate. > There is an mcount ABI difference based on which GCC version you are using, although I wouldn't think it would effect this bit. We are using GCC-4.7 FWIW. David Daney > -- Steve > > > >