[PATCH] Add support for ELF notes

[Sebastian Huber]

On 28.03.23 09:26, Chris Johns wrote:
> On 28/3/2023 6:20 pm, Sebastian Huber wrote:
>> On 28.03.23 09:03, Chris Johns wrote:
>>> On 28/3/2023 5:48 pm, Sebastian Huber wrote:
>>>> On 25.03.23 00:39, Chris Johns wrote:
>>>>> On 24/3/2023 7:32 pm, Sebastian Huber wrote:
>>>>>> On 23.03.23 20:07, Chris Johns wrote:
>>>>>>> On 24/3/2023 3:57 am, Sebastian Huber wrote:
>>>>>>>> On 23.03.23 17:52, Will wrote:
>>>>>>>>> Great idea to store this information in the executable itself. Does this
>>>>>>>>> need
>>>>>>>>> a RTEMS_TEST_STATE_LINK_ONLY test state or something similar for
>>>>>>>>> minimum.exe?
>>>>>>>> With the notes you can build the test. The test runner would look at the
>>>>>>>> notes
>>>>>>>> and then decide if it makes sense to run the test or not. It could still
>>>>>>>> run the
>>>>>>>> minimum.exe and see if it terminates.
>>>>>>> I welcome notes support. Thanks for adding it.
>>>>>>>
>>>>>>> How will we control and manage the notes we support?
>>>>>> In the new elfnote.h header file there are defines for the note type
>>>>>> (domain-specific integer).
>>>>> Great.
>>>>>
>>>>>>> Should we document the top level notes domains (?) with some we control and
>>>>>>> restrict and others users can use? For example `note.rtems.test`,
>>>>>>> `note.rtems.kernel`, `note.rtems.bsp`, and `note.rtems.user`?
>>>>>> The section name doesn't matter. You can divide the number space of the note
>>>>>> type for this.
>>>>> Does this mean we define the numbers or number ranges or is it left open? I am
>>>>> not sure I am following this bit.
>>>> The patch has this:
>>>>
>>>> #define ELF_NOTE_RTEMS_TYPE( _index ) ( ( _index ) + 0x10000 )
>>>>
>>>> We basically have 32-bits available. We could also use something like this:
>>>>
>>>> #define ELF_NOTE_RTEMS_BASE_TYPE( _index ) ( ( _index ) + 0x10000000 )
>>>>
>>>> #define ELF_NOTE_RTEMS_TEST_TYPE( _index ) ( ( _index ) + 0x20000000 )
>>>>
>>>> #define ELF_NOTE_RTEMS_USER_TYPE( _index ) ( ( _index ) + 0x30000000 )
>>>>
>>>> ...
>>>>
>>> Nice.
>> Maybe we should also encode the data type here, for example:
>>
>> #define ELF_NOTE_DATA_TYPE_BOOL 0
>> #define ELF_NOTE_DATA_TYPE_INT8 1
>> #define ELF_NOTE_DATA_TYPE_UINT8 2
>> #define ELF_NOTE_DATA_TYPE_INT16 3
>> #define ELF_NOTE_DATA_TYPE_UINT16 4
>> #define ELF_NOTE_DATA_TYPE_INT32 5
>> #define ELF_NOTE_DATA_TYPE_UINT32 6
>> #define ELF_NOTE_DATA_TYPE_INT64 7
>> #define ELF_NOTE_DATA_TYPE_UINT64 8
>> #define ELF_NOTE_DATA_TYPE_FLOAT32 9
>> #define ELF_NOTE_DATA_TYPE_FLOAT32 10
>> #define ELF_NOTE_DATA_TYPE_FLOAT64 11
>> #define ELF_NOTE_DATA_TYPE_FLOAT64 12
>> #define ELF_NOTE_DATA_TYPE_STRING 13
>> #define ELF_NOTE_DATA_TYPE_BINARY 14
>>
>> #define ELF_NOTE_RTEMS_BASE_TYPE( _data_type, _index ) \
>>    ( ( ( _data_type ) << 28 ) | ( ( _index ) + 0x1000000 ) )
>>
>> This could be used by the host tool to more easily produce the right JSON data.
>>
> Good idea. I cannot think of anything else as scoping would tend to reduce to a
> new type.

Another option would be to add a GNU note type for JSON data. The note 
description would be an arbitrary JSON string. For example:

diff --git a/binutils/readelf.c b/binutils/readelf.c
index cafba9a4f56..1d977376b77 100644
--- a/binutils/readelf.c
+++ b/binutils/readelf.c
@@ -20261,6 +20261,10 @@ print_gnu_note (Filedata * filedata, 
Elf_Internal_Note *pnote)
        print_gnu_property_note (filedata, pnote);
        break;

+    case NT_GNU_JSON:
+      print_json_note (filedata, pnote);
+      break;
+
      default:
        /* Handle unrecognised types.  An error message should have 
already been
          created by get_gnu_elf_note_type(), so all that we need to do 
is to
diff --git a/include/elf/common.h b/include/elf/common.h
index ebcd8f9e82c..c5671447074 100644
--- a/include/elf/common.h
+++ b/include/elf/common.h
@@ -805,6 +805,7 @@
  #define NT_GNU_BUILD_ID                3       /* Generated by ld 
--build-id.  */
  #define NT_GNU_GOLD_VERSION    4       /* Generated by gold.  */
  #define NT_GNU_PROPERTY_TYPE_0  5      /* Generated by gcc.  */
+#define NT_GNU_JSON            6       /* Contains arbitrary JSON data.  */

  #define NT_GNU_BUILD_ATTRIBUTE_OPEN    0x100
  #define NT_GNU_BUILD_ATTRIBUTE_FUNC    0x101

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