From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753204AbdBCNA2 (ORCPT ); Fri, 3 Feb 2017 08:00:28 -0500 Received: from foss.arm.com ([217.140.101.70]:49142 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752388AbdBCNA1 (ORCPT ); Fri, 3 Feb 2017 08:00:27 -0500 Date: Fri, 3 Feb 2017 13:00:26 +0000 From: Will Deacon To: He Kuang Cc: peterz@infradead.org, mingo@redhat.com, acme@kernel.org, alexander.shishkin@linux.intel.com, mhiramat@kernel.org, jolsa@redhat.com, wangnan0@huawei.com, bintian.wang@huawei.com, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH v2 1/3] perf tools: Use offset instead of dwarfnum in register table. Message-ID: <20170203130026.GF11585@arm.com> References: <20170203110607.97529-1-hekuang@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170203110607.97529-1-hekuang@huawei.com> 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 On Fri, Feb 03, 2017 at 11:06:05AM +0000, He Kuang wrote: > This patch changes the 'dwarfnum' to 'offset' in register table, so > the index of array becomes the dwarfnum (the index of each register > defined by DWARF) and the "offset" member means the byte-offset of the > register in (user_)pt_regs. This change makes the code consistent with > x86. > > Acked-by: Masami Hiramatsu > Signed-off-by: He Kuang > --- > tools/perf/arch/arm64/util/dwarf-regs.c | 107 ++++++++++++++++---------------- > 1 file changed, 52 insertions(+), 55 deletions(-) Thanks for splitting this up. Comment below. > diff --git a/tools/perf/arch/arm64/util/dwarf-regs.c b/tools/perf/arch/arm64/util/dwarf-regs.c > index d49efeb..090f36b 100644 > --- a/tools/perf/arch/arm64/util/dwarf-regs.c > +++ b/tools/perf/arch/arm64/util/dwarf-regs.c > @@ -9,72 +9,69 @@ > */ > > #include > +#include /* for struct user_pt_regs */ > #include > > -struct pt_regs_dwarfnum { > +struct pt_regs_offset { > const char *name; > - unsigned int dwarfnum; > + int offset; > }; > > -#define STR(s) #s > -#define REG_DWARFNUM_NAME(r, num) {.name = r, .dwarfnum = num} > -#define GPR_DWARFNUM_NAME(num) \ > - {.name = STR(%x##num), .dwarfnum = num} > -#define REG_DWARFNUM_END {.name = NULL, .dwarfnum = 0} > - > /* > * Reference: > * http://infocenter.arm.com/help/topic/com.arm.doc.ihi0057b/IHI0057B_aadwarf64.pdf > */ > -static const struct pt_regs_dwarfnum regdwarfnum_table[] = { > - GPR_DWARFNUM_NAME(0), > - GPR_DWARFNUM_NAME(1), > - GPR_DWARFNUM_NAME(2), > - GPR_DWARFNUM_NAME(3), > - GPR_DWARFNUM_NAME(4), > - GPR_DWARFNUM_NAME(5), > - GPR_DWARFNUM_NAME(6), > - GPR_DWARFNUM_NAME(7), > - GPR_DWARFNUM_NAME(8), > - GPR_DWARFNUM_NAME(9), > - GPR_DWARFNUM_NAME(10), > - GPR_DWARFNUM_NAME(11), > - GPR_DWARFNUM_NAME(12), > - GPR_DWARFNUM_NAME(13), > - GPR_DWARFNUM_NAME(14), > - GPR_DWARFNUM_NAME(15), > - GPR_DWARFNUM_NAME(16), > - GPR_DWARFNUM_NAME(17), > - GPR_DWARFNUM_NAME(18), > - GPR_DWARFNUM_NAME(19), > - GPR_DWARFNUM_NAME(20), > - GPR_DWARFNUM_NAME(21), > - GPR_DWARFNUM_NAME(22), > - GPR_DWARFNUM_NAME(23), > - GPR_DWARFNUM_NAME(24), > - GPR_DWARFNUM_NAME(25), > - GPR_DWARFNUM_NAME(26), > - GPR_DWARFNUM_NAME(27), > - GPR_DWARFNUM_NAME(28), > - GPR_DWARFNUM_NAME(29), > - REG_DWARFNUM_NAME("%lr", 30), > - REG_DWARFNUM_NAME("%sp", 31), > - REG_DWARFNUM_END, > -}; > +#define REG_OFFSET_NAME(r, num) {.name = "%" #r, \ > + .offset = offsetof(struct user_pt_regs, regs[num])} Whilst this works in practice, this is undefined behaviour for "sp", since you'll go off the end of the regs array. I still think you're better off sticking with the dwarfnum, then just having a dwarfnum2offset macro that multiplies by the size of a register. Will