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

[Jan Beulich]

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.

Jan