From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752080AbbJBMmr (ORCPT ); Fri, 2 Oct 2015 08:42:47 -0400 Received: from foss.arm.com ([217.140.101.70]:40059 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750846AbbJBMmq (ORCPT ); Fri, 2 Oct 2015 08:42:46 -0400 Date: Fri, 2 Oct 2015 13:42:41 +0100 From: Catalin Marinas To: AKASHI Takahiro Cc: zhouchengming1@huawei.com, ard.biesheuvel@linaro.org, dingtianhong@huawei.com, will.deacon@arm.com, linux-kernel@vger.kernel.org, rostedt@goodmis.org, lizefan@huawei.com, Li Bin , guohanjun@huawei.com, linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH] arm64: ftrace: fix function_graph tracer panic Message-ID: <20151002124240.GK6963@e104818-lin.cambridge.arm.com> References: <1443581395-30088-1-git-send-email-huawei.libin@huawei.com> <560CCE91.3020407@linaro.org> <20151001152739.GI6963@e104818-lin.cambridge.arm.com> <560E38C0.7080409@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <560E38C0.7080409@linaro.org> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Oct 02, 2015 at 04:56:48PM +0900, AKASHI Takahiro wrote: > >>On 09/30/2015 11:49 AM, Li Bin wrote: > >>>This is because when using function graph tracer, if the traced > >>>function return value is in multi regs ([0x-07]), return_to_handler > > typo: 0x-07 => x0-x7 I fixed this up. > and pre/post-indexed addressing stp&ldp may save add&sub instructions, but > it's a matter of preference. Doing it this way is more efficient in general as it avoids updating the sp and writing in reverse order. That's the reason we recently changed the kernel_entry/exit macros (see commit 63648dd20fa0 "arm64: entry: use ldp/stp instead of push/pop when saving/restoring regs"). Thanks. -- Catalin