Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755318AbbGVFLe (ORCPT ); Wed, 22 Jul 2015 01:11:34 -0400 Received: from ozlabs.org ([103.22.144.67]:35790 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751594AbbGVFLc (ORCPT ); Wed, 22 Jul 2015 01:11:32 -0400 Message-ID: <1437541889.16792.11.camel@ellerman.id.au> Subject: Re: [PATCH 1/2] Move the pt_regs_offset struct definition from arch to common include file From: Michael Ellerman To: David Long Cc: Rob Herring , "H. Peter Anvin" , Andy Lutomirski , Anton Blanchard , Behan Webster , Benjamin Herrenschmidt , Eric Paris , Heiko Carstens , Ingo Molnar , Jan Willeke , Kees Cook , Martin Schwidefsky , Nikolay Borisov , Oleg Nesterov , Paul Mackerras , Richard Kuo , Robert Richter , Roland McGrath , Russell King , Tejun Heo , Thomas Gleixner , Will Deacon , "linux-arm-kernel@lists.infradead.org" , linux-hexagon@vger.kernel.org, "linux-kernel@vger.kernel.org" , linux-s390@vger.kernel.org, SH-Linux , linux390@de.ibm.com, linuxppc-dev , "x86@kernel.org" Date: Wed, 22 Jul 2015 15:11:29 +1000 In-Reply-To: <55AF2037.2000803@linaro.org> References: <1434386579-6045-1-git-send-email-dave.long@linaro.org> <1434386579-6045-2-git-send-email-dave.long@linaro.org> <5581BCD0.2040405@linaro.org> <1435634945.24866.2.camel@ellerman.id.au> <55AF2037.2000803@linaro.org> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.12.10-0ubuntu1~14.10.1 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3105 Lines: 82 On Wed, 2015-07-22 at 00:46 -0400, David Long wrote: > On 06/29/15 23:29, Michael Ellerman wrote: > > On Wed, 2015-06-17 at 14:30 -0400, David Long wrote: > >> On 06/16/15 09:17, Rob Herring wrote: > >>> On Mon, Jun 15, 2015 at 11:42 AM, David Long wrote: > >>>> > >>>> #define REG_OFFSET_NAME(r) \ > >>>> {.name = #r, .offset = offsetof(struct pt_regs, ARM_##r)} > >>>> #define REG_OFFSET_END {.name = NULL, .offset = 0} > >>> > >>> Can't you also move these? ARM is complicated with the "ARM_" > >>> prefixing, but the others appear to be the same. Maybe you can remove > >>> the prefix or redefine the macro for ARM. > >> > >> That would mandate that all the architecture-specific pt_regs structures > >> would have to use a top-level named field for each named register. > > > > Why does it mandate that? > > > > See eg. powerpc where we use REG_OFFSET_NAME for the top-level named fields and > > then a different macro for the array elements: > > > > #define REG_OFFSET_NAME(r) {.name = #r, .offset = offsetof(struct pt_regs, r)} > > #define GPR_OFFSET_NAME(num) \ > > {.name = STR(gpr##num), .offset = offsetof(struct pt_regs, gpr[num])} > > > > static const struct pt_regs_offset regoffset_table[] = { > > GPR_OFFSET_NAME(0), > > GPR_OFFSET_NAME(1), > > GPR_OFFSET_NAME(2), > > GPR_OFFSET_NAME(3), > > ... > > REG_OFFSET_NAME(nip), > > REG_OFFSET_NAME(msr), > > > > > > So I don't see why REG_OFFSET_NAME couldn't be common. > > > > Sorry for the delay in responding to this. > > OK, so you're saying architectures that don't want this constraint can > make their own macro. Seems to make this whole exercise slightly less > useful, but whatever. Well yeah. In fact of the 4 arches that use REG_OFFSET_NAME, 2 already have another macro for specially named registers (powerpc & sh). > I see three ways to go here: > > 1) Leave it as is. > 2) Force all architectures to use a common definition. > 3) Provide a common definition that all architectures (except "arm") > currently using this functionality will use. > > I have a v2 patch to implement #3, ready to post. Do we think this is > the way to go? Yeah I think it is. How are you making it conditional? Just #ifndef REG_OFFSET_NAME? > I don't like #2 because I really don't want to rename all > uses of the current register fields for arm since this is > architecture-specific code to begin with and since it affects code in 39 > arm source files. I guess you're talking about renaming all the ARM_x regs to x. That would likely cause problems because they're implemented as #defines, eg. #define r0 uregs[0] would probably confuse your assembler. The clean thing to do would be to have the in-kernel struct pt_regs have actual named members, but that would still be an intrusive change. cheers -- 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/