Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754306AbaAULVM (ORCPT ); Tue, 21 Jan 2014 06:21:12 -0500 Received: from cam-admin0.cambridge.arm.com ([217.140.96.50]:54540 "EHLO cam-admin0.cambridge.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754042AbaAULVI (ORCPT ); Tue, 21 Jan 2014 06:21:08 -0500 Date: Tue, 21 Jan 2014 11:20:04 +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 , Steve Capper Subject: Re: [PATCH] ARM64: perf: support dwarf unwinding in compat mode Message-ID: <20140121112004.GH30706@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> <20140117100723.GB16003@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 Mon, Jan 20, 2014 at 05:05:14PM +0000, Jean Pihet wrote: > Hi Will, > > Here is an updated version of the change, which uses compat_sp at only > one place. > The drawback is that compat_user_mode is checked when calling > compat_user_stack_pointer, which seems unnecessary. Unfortunately the > check is not optimized out by the complier as I could check with > objdump -S. > > What do you think? I think that's cleaner and really wouldn't worry about the couple of extra instructions. Cheers, Will > diff --git a/arch/arm64/include/asm/compat.h b/arch/arm64/include/asm/compat.h > index fda2704..e71f81f 100644 > --- a/arch/arm64/include/asm/compat.h > +++ b/arch/arm64/include/asm/compat.h > @@ -228,7 +228,7 @@ static inline compat_uptr_t ptr_to_compat(void __user *uptr) > return (u32)(unsigned long)uptr; > } > > -#define compat_user_stack_pointer() (current_pt_regs()->compat_sp) > +#define compat_user_stack_pointer() (user_stack_pointer(current_pt_regs())) > > static inline void __user *arch_compat_alloc_user_space(long len) > { > diff --git a/arch/arm64/include/asm/ptrace.h b/arch/arm64/include/asm/ptrace.h > index fbb0020..86d5b54 100644 > --- a/arch/arm64/include/asm/ptrace.h > +++ b/arch/arm64/include/asm/ptrace.h > @@ -133,7 +133,7 @@ struct pt_regs { > (!((regs)->pstate & PSR_F_BIT)) > > #define user_stack_pointer(regs) \ > - ((regs)->sp) > + (!compat_user_mode(regs)) ? ((regs)->sp) : ((regs)->compat_sp) > > /* > * Are the current registers suitable for user mode? (used to maintain -- 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/