From mboxrd@z Thu Jan 1 00:00:00 1970 From: hekuang@huawei.com (Hekuang) Date: Sat, 4 Feb 2017 17:03:20 +0800 Subject: [PATCH v2 1/3] perf tools: Use offset instead of dwarfnum in register table. In-Reply-To: <20170203130026.GF11585@arm.com> References: <20170203110607.97529-1-hekuang@huawei.com> <20170203130026.GF11585@arm.com> Message-ID: <589598D8.8050304@huawei.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org hi ? 2017/2/3 21:00, Will Deacon ??: > 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. It's not undefined behaviour here, struct user_pt_regs { __u64 regs[31]; __u64 sp; __u64 pc; __u64 pstate; }; user_pt_regs->regs[31] is user_pt_regs->sp and the offset value is correct. > > 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 I think add a ptregs_offset field is more suitable and makes the code indepent to struct user_pt_regs layout, for example if the structure changed to this: struct user_pt_regs { __u64 sp; __u64 pc; __u64 pstate; __u64 regs[31]; }; The multiply result will be incorrect. Patch updated and the change is similar to commit "4679bccaa308" (perf tools powerpc: Add support for generating bpf prologue) Please review, thanks. From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753989AbdBDJFA (ORCPT ); Sat, 4 Feb 2017 04:05:00 -0500 Received: from szxga03-in.huawei.com ([119.145.14.66]:28026 "EHLO szxga03-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753785AbdBDJE6 (ORCPT ); Sat, 4 Feb 2017 04:04:58 -0500 Subject: Re: [PATCH v2 1/3] perf tools: Use offset instead of dwarfnum in register table. To: Will Deacon References: <20170203110607.97529-1-hekuang@huawei.com> <20170203130026.GF11585@arm.com> CC: , , , , , , , , , From: Hekuang Message-ID: <589598D8.8050304@huawei.com> Date: Sat, 4 Feb 2017 17:03:20 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:38.0) Gecko/20100101 Thunderbird/38.6.0 MIME-Version: 1.0 In-Reply-To: <20170203130026.GF11585@arm.com> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit X-Originating-IP: [10.108.110.166] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org hi 在 2017/2/3 21:00, Will Deacon 写道: > 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. It's not undefined behaviour here, struct user_pt_regs { __u64 regs[31]; __u64 sp; __u64 pc; __u64 pstate; }; user_pt_regs->regs[31] is user_pt_regs->sp and the offset value is correct. > > 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 I think add a ptregs_offset field is more suitable and makes the code indepent to struct user_pt_regs layout, for example if the structure changed to this: struct user_pt_regs { __u64 sp; __u64 pc; __u64 pstate; __u64 regs[31]; }; The multiply result will be incorrect. Patch updated and the change is similar to commit "4679bccaa308" (perf tools powerpc: Add support for generating bpf prologue) Please review, thanks.