linux-kernel - Re: [PATCH] perf test: Skip test 68 for Powerpc

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Date:   Thu, 10 Dec 2020 11:22:49 +0530
From:   Ravi Bangoria <ravi.bangoria@...ux.ibm.com>
To:     Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:     Thomas Richter <tmricht@...ux.ibm.com>,
        Kajol Jain <kjain@...ux.ibm.com>, jolsa@...hat.com,
        namhyung@...nel.org, linux-perf-users@...r.kernel.org,
        linux-kernel@...r.kernel.org, irogers@...gle.com,
        rbernon@...eweavers.com, maddy@...ux.ibm.com,
        atrajeev@...ux.vnet.ibm.com,
        Ravi Bangoria <ravi.bangoria@...ux.ibm.com>
Subject: Re: [PATCH] perf test: Skip test 68 for Powerpc



On 12/9/20 11:19 PM, Arnaldo Carvalho de Melo wrote:
> Em Tue, Dec 08, 2020 at 10:32:33PM +0530, Ravi Bangoria escreveu:
>> On 12/8/20 8:13 PM, Thomas Richter wrote:
>>> On 12/7/20 5:35 PM, Arnaldo Carvalho de Melo wrote:
>>>> Em Tue, Nov 24, 2020 at 03:04:53PM +0530, Ravi Bangoria escreveu:
>>>>> On 11/19/20 7:20 PM, Kajol Jain wrote:
>>>>>> Commit ed21d6d7c48e6e ("perf tests: Add test for PE binary format support")
>>>>>> adds a WINDOWS EXE file named tests/pe-file.exe, which is
>>>>>> examined by the test case 'PE file support'. As powerpc doesn't support
>>>>>> it, we are skipping this test.
> 
>>>>>> Result in power9 platform before this patach:
>>>>>> [command]# ./perf test -F 68
>>>>>> 68: PE file support                               : Failed!
> 
>>>>>> Result in power9 platform after this patch:
>>>>>> [command]# ./perf test -F 68
>>>>>> 68: PE file support                               : Skip
> 
>>>>>> Signed-off-by: Kajol Jain <kjain@...ux.ibm.com>
> 
>>>>> Reviewed-by: Ravi Bangoria <ravi.bangoria@...ux.ibm.com>
> 
>>>> But why is it failing? I.e. what is that
> 
>>>>    perf test -v -F 68
> 
>>>> outputs?
> 
>>>> Using 'perf report' on a perf.data file containing samples in such
>>>> binaries, collected on x86 should work on whatever workstation a
>>>> developer uses.
> 
>>>> Say, on a MacBook aarch64 one can look at a perf.data file collected on
>>>> a x86_64 system where Wine running a PE binary was present.
> 
>>> What is the distro you are using?
>>> I observed the same issue on s390 but this was fixed for fedora33 somehow.
>>> The error just went away after a dnf update....
> 
>>> [root@...lp76 perf]# cat /etc/fedora-release
>>> Fedora release 33 (Thirty Three)
>>> [root@...lp76 perf]# ./perf test -F 68
>>> 68: PE file support                                                 : Ok
>>> [root@...lp76 perf]#
> 
>>> However on my fedora32 machine it still fails:
>>> [root@...lp46 perf]# cat /etc/fedora-release
>>> Fedora release 32 (Thirty Two)
>>> [root@...lp46 perf]# ./perf test -F 68
>>> 68: PE file support                                                 : FAILED!
>>> [root@...lp46 perf]#
>>>
>>> Note that I am running the same kernel on both machines: linux 5.10.0rc7 downloaded
>>> this morning.
>>>
>>
>> Ok that's interesting. I don't see that on powerpc.
>>
>> Fedora 32 with 5.10.0-rc2+ kernel:
>>
>>    $ ./perf test -vv -F 68
>>    68: PE file support                                                 :
>>    --- start ---
>>    filename__read_build_id: cannot read ./tests/pe-file.exe bfd file.
>>    FAILED tests/pe-file-parsing.c:40 Failed to read build_id
>>    ---- end ----
>>    PE file support: FAILED!
>>
>> Fedora 33 with 5.10.0-rc3 kernel:
>>
>>    $ ./perf test -vv -F 68
>>    68: PE file support                                                 :
>>    --- start ---
>>    filename__read_build_id: cannot read ./tests/pe-file.exe bfd file.
>>    FAILED tests/pe-file-parsing.c:40 Failed to read build_id
>>    ---- end ----
>>    PE file support: FAILED!
>>
>> Ubuntu 18.04.5 with 4.15.0-126-generic kernel:
>>
>>    $ ./perf test -vv -F 68
>>    68: PE file support                                                 :
>>    --- start ---
>>    filename__read_build_id: cannot read ./tests/pe-file.exe bfd file.
>>    FAILED tests/pe-file-parsing.c:41 Failed to read build_id
>>    ---- end ----
>>    PE file support: FAILED!
>>
>>
>> I assumed bfd is not capable to parse PE files on powerpc. Though,
>> I didn't check it in more detail. I'll look into it tomorrow.
> 
> Humm, so this is something related to installation? I.e. that
> pe-file.exe isn't being found...
> 
> It first assumes that the developers are in the tools/perf/ directory,
> can you please add the patch below and see if it helps?

I'm using upstream perf from tools/perf/

I checked bfd code and it's bfd_check_format() who is returning error
"bfd_error_file_not_recognized".

I cross verified with objdump as well:

On x86:

   $ objdump -d ./tests/pe-file.exe
   ./tests/pe-file.exe:     file format pei-x86-64
     
   Disassembly of section .text:
   
   0000000000401000 <__mingw_invalidParameterHandler>:
     401000:       c3                      retq
     401001:       66 66 2e 0f 1f 84 00    data16 nopw %cs:0x0(%rax,%rax,1)
     401008:       00 00 00 00
     40100c:       0f 1f 40 00             nopl   0x0(%rax)

On powerpc:

   $ objdump -d ./tests/pe-file.exe
   objdump: ./tests/pe-file.exe: file format not recognized

Objdump is also returning *same* error.

I dig more into bfd logs and found that Powerpc PE support was removed
recently (Jul 2020) with this commit:
https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=fe49679d5193f6ff7cfd333e30883d293112a3d1

Ravi