Re: [PATCH 1/2] selftests/ftrace: Force C locale for readelf in uprobe test

[Rui Qi]

On 8/7/26 9:47 AM, Masami Hiramatsu (Google) wrote:
> On Thu,  6 Aug 2026 16:31:00 +0800
> "Rui Qi" <qirui.001@xxxxxxxxxxxxx> wrote:
> 
>> The add_remove_uprobe test parses the entry point from readelf -h output
>> by looking for the English "Entry" field. readelf output is localized
>> via gettext, while the ftracetest runner does not force LC_ALL=C and the
>> top-level Makefile leaves LANG effective for child processes.
> 
> Hmm, to make it safer, I think we should force LC_ALL=C in the top level
> of ftracetest, instead of setting it in each test case.
> 
> Thank you,
> 

Thank you for the suggestion.

Agreed, setting LC_ALL=C in the ftracetest runner is better than fixing
this one readelf invocation. I will update ftracetest to export LC_ALL=C
so all test cases inherit the C locale, and send a v2.

Thanks,
Rui


>>
>> If readelf prints a translated field name, ENTRYPOINT becomes empty and
>> the uprobe_events write is rejected because the offset after PATH: is
>> missing.
>>
>> Run readelf with LC_ALL=C so the parsed header field remains stable
>> across locales.
>>
>> Signed-off-by: Rui Qi <qirui.001@xxxxxxxxxxxxx>
>> ---
>>  .../selftests/ftrace/test.d/dynevent/add_remove_uprobe.tc       | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/tools/testing/selftests/ftrace/test.d/dynevent/add_remove_uprobe.tc b/tools/testing/selftests/ftrace/test.d/dynevent/add_remove_uprobe.tc
>> index f2048c244526..f33a863be68b 100644
>> --- a/tools/testing/selftests/ftrace/test.d/dynevent/add_remove_uprobe.tc
>> +++ b/tools/testing/selftests/ftrace/test.d/dynevent/add_remove_uprobe.tc
>> @@ -12,7 +12,7 @@ echo 0 > events/enable
>>  echo > dynamic_events
>>  
>>  REALBIN=`readlink -f /bin/sh`
>> -ENTRYPOINT=`readelf -h ${REALBIN} | grep Entry | sed -e 's/[^0]*//'`
>> +ENTRYPOINT=`LC_ALL=C readelf -h ${REALBIN} | grep Entry | sed -e 's/[^0]*//'`
>>  
>>  echo "p:myevent ${REALBIN}:${ENTRYPOINT}" >> uprobe_events
>>  
>> -- 
>> 2.20.1
>