Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934342AbbGVNbJ (ORCPT ); Wed, 22 Jul 2015 09:31:09 -0400 Received: from mail-qk0-f178.google.com ([209.85.220.178]:33186 "EHLO mail-qk0-f178.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932612AbbGVNbF (ORCPT ); Wed, 22 Jul 2015 09:31:05 -0400 Message-ID: <55AF9B13.4010406@linaro.org> Date: Wed, 22 Jul 2015 09:30:59 -0400 From: David Long User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.2.0 MIME-Version: 1.0 To: Michael Ellerman 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" Subject: Re: [PATCH 1/2] Move the pt_regs_offset struct definition from arch to common include file 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> <1437541889.16792.11.camel@ellerman.id.au> In-Reply-To: <1437541889.16792.11.camel@ellerman.id.au> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3496 Lines: 95 On 07/22/15 01:11, Michael Ellerman wrote: > 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'm just defining a new macro for arm. The macro is only invoked in one arm file. Then the REG_OFFSET_NAME macro goes unused for this architecture. >> 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. > Yeah, and I had not looked further to the implications of doing that but I see you've found where it is a genuine problem. > 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 > > Thanks, -dl -- 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/