Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755824AbbEURzz (ORCPT ); Thu, 21 May 2015 13:55:55 -0400 Received: from foss.arm.com ([217.140.101.70]:42076 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755833AbbEURzv (ORCPT ); Thu, 21 May 2015 13:55:51 -0400 Date: Thu, 21 May 2015 18:55:46 +0100 From: Catalin Marinas To: David Long Cc: "Jon Medhurst (Tixy)" , Steve Capper , Ananth N Mavinakayanahalli , Will Deacon , linux-kernel@vger.kernel.org, Anil S Keshavamurthy , sandeepa.s.prabhu@gmail.com, Masami Hiramatsu , Russell King , William Cohen , davem@davemloft.net, linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH v6 1/6] arm64: Add HAVE_REGS_AND_STACK_ACCESS_API feature Message-ID: <20150521175546.GP29424@e104818-lin.cambridge.arm.com> References: <1429561187-3661-1-git-send-email-dave.long@linaro.org> <1429561187-3661-2-git-send-email-dave.long@linaro.org> <20150520133944.GA29424@e104818-lin.cambridge.arm.com> <555D5114.9010701@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <555D5114.9010701@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 Content-Length: 3461 Lines: 98 On Wed, May 20, 2015 at 11:29:24PM -0400, David Long wrote: > On 05/20/15 09:39, Catalin Marinas wrote: > >On Mon, Apr 20, 2015 at 04:19:42PM -0400, David Long wrote: > >>diff --git a/arch/arm64/include/uapi/asm/ptrace.h b/arch/arm64/include/uapi/asm/ptrace.h > >>index 6913643..58c0223 100644 > >>--- a/arch/arm64/include/uapi/asm/ptrace.h > >>+++ b/arch/arm64/include/uapi/asm/ptrace.h > >>@@ -61,6 +61,42 @@ > >> > >> #ifndef __ASSEMBLY__ > >> > >>+#define ARM_pstate pstate > >>+#define ARM_pc pc > >>+#define ARM_sp sp > >>+#define ARM_lr regs[30] > >>+#define ARM_fp regs[29] > >>+#define ARM_x28 regs[28] > >>+#define ARM_x27 regs[27] > >>+#define ARM_x26 regs[26] > >>+#define ARM_x25 regs[25] > >>+#define ARM_x24 regs[24] > >>+#define ARM_x23 regs[23] > >>+#define ARM_x22 regs[22] > >>+#define ARM_x21 regs[21] > >>+#define ARM_x20 regs[20] > >>+#define ARM_x19 regs[19] > >>+#define ARM_x18 regs[18] > >>+#define ARM_ip1 regs[17] > >>+#define ARM_ip0 regs[16] > >>+#define ARM_x15 regs[15] > >>+#define ARM_x14 regs[14] > >>+#define ARM_x13 regs[13] > >>+#define ARM_x12 regs[12] > >>+#define ARM_x11 regs[11] > >>+#define ARM_x10 regs[10] > >>+#define ARM_x9 regs[9] > >>+#define ARM_x8 regs[8] > >>+#define ARM_x7 regs[7] > >>+#define ARM_x6 regs[6] > >>+#define ARM_x5 regs[5] > >>+#define ARM_x4 regs[4] > >>+#define ARM_x3 regs[3] > >>+#define ARM_x2 regs[2] > >>+#define ARM_x1 regs[1] > >>+#define ARM_x0 regs[0] > >>+#define ARM_ORIG_x0 orig_x0 > > > >I replied some time ago on this part. I don't see the point these > >macros. > > I replied belatedly on April 20 saying what I did matches (more or less) how > it's done on various other platforms, including arm and powerpc. > It looks like this comes from the pt_regs structure defining the > registers as an array instead of a list of structure fields. It looks > to me like that design choice is pretty widely depended upon now and > would be quite disruptive to change. It also seems to me a relatively > clean way to do it on systems with a uniform register set. I see why we need to cope with the regs[] array but why do we need these definitions in a uapi file? > >>+ > >> /* > >> * User structures for general purpose, floating point and debug registers. > >> */ > >>diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c > >>index d882b83..a889f79 100644 > >>--- a/arch/arm64/kernel/ptrace.c > >>+++ b/arch/arm64/kernel/ptrace.c > >>@@ -48,6 +48,122 @@ > >> #define CREATE_TRACE_POINTS > >> #include > >> > >>+struct pt_regs_offset { > >>+ const char *name; > >>+ int offset; > >>+}; > >>+ > >>+#define REG_OFFSET_NAME(r) \ > >>+ {.name = #r, .offset = offsetof(struct pt_regs, ARM_##r)} > > >Can you not just use "offsetof(struct pt_regs, r)" here? That would be > >the same as x86, powerpc. > > The registers (except for pc, pstate, and sp) are not separate structure > fields, they are slots in a single array. To reference them the symbolic > name has to be converted to an index (integer register number) somehow. Can we not keep them local to this file, say __reg_x0 etc. (something to make it clear they are for internal use)? -- Catalin -- 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/