linux-kernel - Re: [PATCH 2/2] perf tools: Introduce regs_query_register

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Date:   Wed, 25 Jan 2017 15:26:44 +0800
From:   Hekuang <hekuang@...wei.com>
To:     Arnaldo Carvalho de Melo <acme@...nel.org>,
        Will Deacon <will.deacon@....com>
CC:     <peterz@...radead.org>, <mingo@...hat.com>,
        <alexander.shishkin@...ux.intel.com>, <jolsa@...hat.com>,
        <mhiramat@...nel.org>, <wangnan0@...wei.com>,
        <bintian.wang@...wei.com>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/2] perf tools: Introduce regs_query_register_offset()
 for arm64

hi

在 2017/1/25 3:09, Arnaldo Carvalho de Melo 写道:
> Em Tue, Jan 24, 2017 at 06:25:18PM +0000, Will Deacon escreveu:
>> On Tue, Jan 24, 2017 at 10:30:15AM +0000, He Kuang wrote:
>>> Since HAVE_KPROBES can be enabled in arm64, this patch introduces
>>> regs_query_register_offset() to convert register name to offset for
>>> arm64, so the BPF prologue feature is ready to use.
>>>
>>> This patch also changes the 'dwarfnum' to 'offset' in register table,
>>> so the related functions are consistent with x86.
>>>
>>> Signed-off-by: He Kuang <hekuang@...wei.com>
>   
>> It would've been nice to have been cc'd on this. In future, please at least
>> cc linux-arm-kernel for patches directly changing arm/arm64 code.
>   
>>> +	GPR_OFFSET_NAME(30),
>>> +	{.name = "lr", .offset = offsetof(struct user_pt_regs, regs[30])},
>>> +	REG_OFFSET_NAME(sp),
>   
>> Don't sp and lr need the leading '%'?
>   
>>> +	REG_OFFSET_NAME(pc),
>>> +	REG_OFFSET_NAME(pstate),
>   
>> The AArch64 DWARF spec says that DWARF register 32 is "RESERVED" and
>> register 33 is the ELR, so these pc/pstate entries are wrong.
>   
>> However, with those changes, I think this patch can simply be ignored and
>> mainline is doing the right thing.
> Ok, thanks for checking, dropping this patch then.
>
> - Arnaldo
>

The purpose of this patch is mainly on enable bpf prologue on arm64,
a new v2 version is sent and fix the problem mentioned by Will, thank
you for reviewing this.