Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752513AbaAQKIK (ORCPT ); Fri, 17 Jan 2014 05:08:10 -0500 Received: from cam-admin0.cambridge.arm.com ([217.140.96.50]:60016 "EHLO cam-admin0.cambridge.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752492AbaAQKIF (ORCPT ); Fri, 17 Jan 2014 05:08:05 -0500 Date: Fri, 17 Jan 2014 10:07:23 +0000 From: Will Deacon To: Jean Pihet Cc: "linux-kernel@vger.kernel.org" , "linaro-kernel@lists.linaro.org" , "linux-arm-kernel@lists.infradead.org" , Arnaldo , "patches@linaro.org" , Jiri Olsa , Ingo Molnar Subject: Re: [PATCH] ARM64: perf: support dwarf unwinding in compat mode Message-ID: <20140117100723.GB16003@mudshark.cambridge.arm.com> References: <1389869123-5884-1-git-send-email-jean.pihet@linaro.org> <20140116115634.GE30257@mudshark.cambridge.arm.com> <20140116125727.GI30257@mudshark.cambridge.arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jan 17, 2014 at 09:00:09AM +0000, Jean Pihet wrote: > On 16 January 2014 14:47, Jean Pihet wrote: > >> So the simplest thing would be to make compat_user_stack_pointer expand to > >> user_stack_pointer(current_pt_regs()) on arm64 and merge that in with your > >> original patch fixing user_stack_pointer. > > I see 2 issues in your proposal: > > 1) user_stack_pointer(regs) calls compat_user_stack_pointer if > compat_user_mode(regs)) and compat_user_stack_pointer expands to > user_stack_pointer. I see a circular dependency in the macros. Not today it doesn't, so you just need to avoid writing the circular dependency and instead make user_stack_pointer access (regs)->compat_sp instead. > 2) current_pt_regs() returns the current task regs although perf > passes a regs struct that had been recorded previously. Yes, but compat_user_stack_pointer doesn't take a regs paramater anyway, so there's no change in behaviour here. Will -- 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/