linux-kernel - Re: [PATCH v3 3/4] perf annotate: add powerpc support

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Message-Id: <5784543A.9030801@linux.vnet.ibm.com>
Date:	Tue, 12 Jul 2016 07:51:46 +0530
From:	Ravi Bangoria <ravi.bangoria@...ux.vnet.ibm.com>
To:	acme@...nel.org
Cc:	Michael Ellerman <mpe@...erman.id.au>,
	linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
	anton@...abs.org, ananth@...ibm.com, dja@...ens.net,
	naveen.n.rao@...ux.vnet.ibm.com, David.Laight@...LAB.COM,
	Ravi Bangoria <ravi.bangoria@...ux.vnet.ibm.com>
Subject: Re: [PATCH v3 3/4] perf annotate: add powerpc support

Hi Arnaldo,

On Friday 08 July 2016 02:01 PM, Michael Ellerman wrote:
> Ravi Bangoria <ravi.bangoria@...ux.vnet.ibm.com> writes:
>
>> On Wednesday 06 July 2016 03:38 PM, Michael Ellerman wrote:
>>
>> I've sent v4 which enables annotate for bctr' instructions.
>>
>> for 'bctr', it will show down arrow(indicate jump) and 'bctrl' will show
>> right arrow(indicate call). But no navigation options will be provided.
>> By pressing Enter key on that, message will be shown that like
>> "Invalid target"
> Great thanks.

I've sent v4 series. Please review it.

-Ravi

>>>>> It doesn't look like we have the opcode handy here? Could we get it somehow?
>>>>> That would make this a *lot* more robust.
>>>> objdump prints machine code, but I don't know how difficult that would
>>>> be to parse to get opcode.
>>> Normal objdump -d output includes the opcode, eg:
>>>
>>> c00000000000886c:       2c 2c 00 00     cmpdi   r12,0
>>>                           ^^^^^^^^^^^
>>>
>>> The only thing you need to know is the endian and you can reconstruct
>>> the raw instruction.
>>>
>>> Then you can just decode the opcode, see how we do it in the kernel with
>>> eg. instr_is_relative_branch().
>> I'm sorry. I was thinking that you wants to show opcodes with perf
>> annotate. But you were asking to use opcode instead of parsing
>> instructions.
> Yeah.
>
>> This looks like rewrite parsing code. I don't know whether there is any
>> library already available for this which we can directly use. I'm thinking
>> about this.
> OK don't worry about it for now. We should get this merged for starters
> and we can always improve it later.
>
> cheers
>