[PATCH] readelf: objdump: sframe: fix dumping with section name

[Indu Bhagat]

On 7/21/25 3:36 AM, Jan Beulich wrote:
> On 21.07.2025 08:00, Indu Bhagat wrote:
>> On 7/20/25 10:46 PM, Jan Beulich wrote:
>>> On 20.07.2025 07:34, Indu Bhagat via Binutils wrote:
>>>> Fix PR binutils/33186 - No SFrame dump if section name is not .sframe
>>>>
>>>> When no section name is given, ensure that the dumping routines are able
>>>> to dump a section of type SHT_GNU_SFRAME and not fail if the SFrame
>>>> section name is not ".sframe".
>>>>
>>>> For objdump, in dump_dwarf_section (), use the match string of ".sframe"
>>>> to find the corresponding debug_displays[] item for SFrame section.
>>>> Doing this ensures that any call to dump_dwarf_section () with the
>>>> section pointing to the SFrame section (with name possibly different
>>>> from ".sframe") will successfully dump the SFrame section.
>>>>
>>>> If the SFrame section is named anything but ".sframe", the desirable
>>>> behaviour is:
>>>>
>>>> $ readelf -S sort | grep sframe
>>>>     [NN] .sframe2          GNU_SFRAME       0000000000NNNNNN  0000NNNN
>>>> $ objdump --sframe sort
>>>>
>>>> sort:     file format elf64-x86-64
>>>>
>>>> No .sframe section present
>>>>
>>>> So, set dump_sframe_section_name to ".sframe" if user specifies no
>>>> section name.  In the error checking done in dump_sframe_section, add
>>>> the case when user specifies a valid section name but one that does not
>>>> contain SFrame section data.
>>>>
>>>> Similar changes in readelf.
>>>>
>>>> Add a test each for objdump and readelf to dump a renamed section.  Use
>>>> gas_sframe_check to limit the execution of these tests only when a gas
>>>> supporting SFrame format is present.
>>>>
>>>> binutils/
>>>> 	PR binutils/33186
>>>> 	* objdump.c (dump_dwarf_section): Set match to ".sframe" which
>>>> 	corresponds to the name in the debug_displays[] entry for
>>>> 	SFrame section.
>>>> 	(dump_sframe_section): Check if the user specified section name
>>>> 	contains SFrame data.
>>>> 	(main): Set default section name to ".sframe".
>>>> 	* readelf.c (display_debug_section): Adjust checks to find the
>>>> 	debug_diplay[] item for the input SFrame section in the arg.
>>>> binutils/testsuite/
>>>> 	PR binutils/33186
>>>> 	* binutils-all/x86-64/objdump-sframe-01.d: New test.
>>>> 	* binutils-all/x86-64/readelf-sframe-01.d: New test.
>>>> 	* binutils-all/x86-64/sframe-func.s: New test.
>>>>
>>>> ----
>>>>
>>>> After the patch:
>>>>
>>>> $ objcopy --rename-section .sframe=.sframe2 sort
>>>> $ $ readelf -S sort | grep sframe
>>>>     [NN] .sframe2          GNU_SFRAME       0000000000NNNNNN  0000NNNN
>>>>
>>>> $ readelf  --sframe=.sframe sort
>>>> readelf: Warning: Section '.sframe' was not dumped because it does not exist
>>>> $ readelf  --sframe sort
>>>> readelf: Warning: Section '.sframe' was not dumped because it does not exist
>>>
>>> Is this and ...
>>>
>>>> $ readelf  --sframe=.sframe2 sort
>>>> Contents of the SFrame section .sframe2:
>>>>     Header :
>>>>
>>>>       Version: SFRAME_VERSION_2
>>>>      ...
>>>> $ readelf  --sframe=.ctf sort
>>>> Unrecognized debug section: .ctf
>>>>
>>>> $ objdump  --sframe=.sframe sort
>>>> No .sframe section present
>>>> $ objdump  --sframe sort
>>>> No .sframe section present
>>>
>>> ... this really what is wanted? Shouldn't plain --sframe dump any GNU_SFRAME
>>> sections, no matter what their names? (IOW there may want to be further test
>>> cases covering the situation with more than one GNU_SFRAME section in an
>>> object file.)
>>>
>>
>> This is, for now, in alignment with the intention.  The options text
>> communicated so far:
>>
>> $ objdump --help | grep sframe
>>         --sframe[=SECTION]   Display SFrame info from SECTION, (default
>> '.sframe')
>>
>> $ readelf --help | grep sframe
>>     --sframe[=NAME]        Display SFrame info from section NAME,
>> (default '.sframe')
> 
> Hmm, this (documented or not) behavior feels pretty counterintuitive to me.
> 

I am not sure if its worth increasing the complexity at this time to 
support an option which dumps non-".sframe" named sections or multiple 
SHT_GNU_SFRAME Sections by default for "readelf --sframe" or "objdump 
--sframe" at this time.

My intention was to fix the options to at least get them to work as 
documented.