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

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Date:   Mon, 24 Feb 2020 14:51:41 +0100
From:   Jiri Olsa <jolsa@...hat.com>
To:     Ravi Bangoria <ravi.bangoria@...ux.ibm.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
Subject: Re: [PATCH v3 2/2] Support interactive annotation of code without
 symbols

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 ;-)

jirka