Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932108AbZJVSfb (ORCPT ); Thu, 22 Oct 2009 14:35:31 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753334AbZJVSfa (ORCPT ); Thu, 22 Oct 2009 14:35:30 -0400 Received: from mail3.caviumnetworks.com ([12.108.191.235]:3220 "EHLO mail3.caviumnetworks.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753202AbZJVSfa (ORCPT ); Thu, 22 Oct 2009 14:35:30 -0400 Message-ID: <4AE0A5BE.8000601@caviumnetworks.com> Date: Thu, 22 Oct 2009 11:34:38 -0700 From: David Daney User-Agent: Thunderbird 2.0.0.21 (X11/20090320) MIME-Version: 1.0 To: wuzhangjin@gmail.com, Richard Sandiford , Adam Nemet CC: rostedt@goodmis.org, linux-kernel@vger.kernel.org, linux-mips@linux-mips.org, Thomas Gleixner , Ralf Baechle , Nicholas Mc Guire Subject: Re: [PATCH -v4 4/9] tracing: add static function tracer support for MIPS References: <028867b99ec532b84963a35e7d552becc783cafc.1256135456.git.wuzhangjin@gmail.com> <2f73eae542c47ac5bbb9f7280e6c0271d193e90d.1256135456.git.wuzhangjin@gmail.com> <3f0d3515f74a58f4cfd11e61b62a129fdc21e3a7.1256135456.git.wuzhangjin@gmail.com> <1256138686.18347.3039.camel@gandalf.stny.rr.com> <1256233679.23653.7.camel@falcon> In-Reply-To: <1256233679.23653.7.camel@falcon> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-OriginalArrivalTime: 22 Oct 2009 18:34:38.0843 (UTC) FILETIME=[4FFF54B0:01CA5346] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1677 Lines: 52 Wu Zhangjin wrote: > On Wed, 2009-10-21 at 11:24 -0400, Steven Rostedt wrote: [...] >>> + >>> +NESTED(_mcount, PT_SIZE, ra) >>> + RESTORE_SP_FOR_32BIT >>> + PTR_LA t0, ftrace_stub >>> + PTR_L t1, ftrace_trace_function /* please don't use t1 later, safe? */ >> Is t0 and t1 safe for mcount to use? Remember, mcount does not follow >> the dynamics of C function ABI. > > So, perhaps we can use the saved registers(a0,a1...) instead. > a0..a7 may not always be saved. You can use at, v0, v1 and all the temporary registers. Note that for the 64-bit ABIs sometimes the names t0-t4 shadow a4-a7. So for a 64-bit kernel, you can use: $1, $2, $3, $12, $13, $14, $15, $24, $25, noting that at == $1 and contains the callers ra. For a 32-bit kernel you can add $8, $9, $10, and $11 This whole thing seems a little fragile. I think it might be a good idea to get input from Richard Sandiford, and/or Adam Nemet about this approach (so I add them to the CC). This e-mail thread starts here: http://www.linux-mips.org/archives/linux-mips/2009-10/msg00286.html and here: http://www.linux-mips.org/archives/linux-mips/2009-10/msg00290.html David Daney > Regards! > > -- > 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/ > -- 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/