linux-kernel - Re: [PATCH v3 2/2] Support interactive annotation of code without symbols

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Date:   Mon, 24 Feb 2020 19:34:55 +0530
From:   Ravi Bangoria <ravi.bangoria@...ux.ibm.com>
To:     Jiri Olsa <jolsa@...hat.com>
Cc:     Jin Yao <yao.jin@...ux.intel.com>,
        alexander.shishkin@...ux.intel.com, acme@...nel.org,
        jolsa@...nel.org, peterz@...radead.org, mingo@...hat.com,
        Linux-kernel@...r.kernel.org, ak@...ux.intel.com,
        kan.liang@...el.com, yao.jin@...el.com,
        Ravi Bangoria <ravi.bangoria@...ux.ibm.com>
Subject: Re: [PATCH v3 2/2] Support interactive annotation of code without
 symbols



On 2/24/20 7:21 PM, Jiri Olsa wrote:
> On Mon, Feb 24, 2020 at 06:55:12PM +0530, Ravi Bangoria wrote:
>> Hi Jin,
>>
>> On 2/24/20 7:52 AM, Jin Yao wrote:
>>> For perf report on stripped binaries it is currently impossible to do
>>> annotation. The annotation state is all tied to symbols, but there are
>>> either no symbols, or symbols are not covering all the code.
>>>
>>> We should support the annotation functionality even without symbols.
>>>
>>> This patch fakes a symbol and the symbol name is the string of address.
>>> After that, we just follow current annotation working flow.
>>>
>>> For example,
>>>
>>> 1. perf report
>>>
>>> Overhead  Command  Shared Object     Symbol
>>>     20.67%  div      libc-2.27.so      [.] __random_r
>>>     17.29%  div      libc-2.27.so      [.] __random
>>>     10.59%  div      div               [.] 0x0000000000000628
>>>      9.25%  div      div               [.] 0x0000000000000612
>>>      6.11%  div      div               [.] 0x0000000000000645
>>>
>>> 2. Select the line of "10.59%  div      div               [.] 0x0000000000000628" and ENTER.
>>>
>>> Annotate 0x0000000000000628
>>> Zoom into div thread
>>> Zoom into div DSO (use the 'k' hotkey to zoom directly into the kernel)
>>> Browse map details
>>> Run scripts for samples of symbol [0x0000000000000628]
>>> Run scripts for all samples
>>> Switch to another data file in PWD
>>> Exit
>>>
>>> 3. Select the "Annotate 0x0000000000000628" and ENTER.
>>>
>>> Percent│
>>>          │
>>>          │
>>>          │     Disassembly of section .text:
>>>          │
>>>          │     0000000000000628 <.text+0x68>:
>>>          │       divsd %xmm4,%xmm0
>>>          │       divsd %xmm3,%xmm1
>>>          │       movsd (%rsp),%xmm2
>>>          │       addsd %xmm1,%xmm0
>>>          │       addsd %xmm2,%xmm0
>>>          │       movsd %xmm0,(%rsp)
>>>
>>> Now we can see the dump of object starting from 0x628.
>>
>> If I press 'a' on address, it's not annotating. But if I annotate
>> by pressing enter, like you explained, it works. Is it intentional?
> 
> I saw that too, but I thought it's unrelated issue,
> because we played with that just recently
> 
> if you go through the 'enter' way and back, then the
> next time 'a' works ;-)

Yes.

I liked the series so I was trying out the patches. Just reporting issues I found...

jump/call arrows are also screwed up.. Like jump instruction is showing call arrows.
But these all are minor issues and can be fixed later on. I don't mind ;)

Ravi