Re: [PATCH 2/4] Add Jeff Mahoney's py-crash patches.

[Jeff Mahoney <jeffm at suse dot com>]

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On 2/1/16 9:55 PM, Jeff Mahoney wrote:
> On 2/1/16 5:22 PM, Doug Evans wrote:
>> On Sun, Jan 31, 2016 at 1:44 PM, Ales Novak <alnovak@suse.cz> 
>> wrote:
>>> --- gdb/Makefile.in              |  12 ++ 
>>> gdb/python/py-minsymbol.c    | 353 
>>> +++++++++++++++++++++++++++++++++++++ gdb/python/py-objfile.c |
>>> 29 +++- gdb/python/py-section.c      | 401 
>>> +++++++++++++++++++++++++++++++++++++++++++ 
>>> gdb/python/py-symbol.c       |  52 ++++-- 
>>> gdb/python/python-internal.h |  14 ++ gdb/python/python.c |   7
>>> +- 7 files changed, 853 insertions(+), 15 deletions(-) create
>>> mode 100644 gdb/python/py-minsymbol.c create mode 100644 
>>> gdb/python/py-section.c
> 
> 
>> Hi.
> 
> Hi Doug -
> 
>> Part of what this patch is doing is exporting bfd to python.
>> E.g., all the SEC_* constants.
> 
>> As a rule we absolutely discourage people from using bfd outside 
>> of the the binutils+gdb source tree. Either this rule needs to 
>> change, or I don't think we can allow this patch. I'd be
>> interested to hear what others in the community think.
> 
> That's unfortunate.  The Linux kernel uses ELF sections for a
> number of purposes.  Most notably is the definition of per-cpu
> variables. Without the ELF section, we can't resolve the addresses
> for the variables.  So, from our perspective, it's a requirement.
> 
>> For myself, I would much rather export ELF separately (e.g., a 
>> separate python API one can use independent of any particular
>> tool, including gdb), and then have gdb provide the necessary
>> glue to use this API. [I can imagine some compromises being
>> needed, at least for now; e.g., it'd be cumbersome to read in all
>> ELF symbols twice. But fixing that is just an optimization.]
> 
> Ok, that's doable.  As it is, the section code mixes GDB and BFD 
> pretty heavily.  It shouldn't be too difficult to separate the two
> out and push the section stuff into a new BFD python interface and 
> associate the objfiles with it.

And here's what I've come up with.  Does this constitute enough of a
separation?  It /should/ cross over into the BFD code in the same way
that the GDB code does: As soon as we hit a bfd object or a
bfd_section object, we call into bfd's new python API to generate the
objects.

https://jeffm.io/git/cgit.cgi/gnu/binutils-gdb/log/?h=gdb/python-bfd

For the fully-integrated kdump work, use the python-bfd-kdump branch
(or SUSE folks, python-bfd-kdump-buildid will pick up the separate
debuginfos as we usually expect).

- -Jeff

>>> ... +  if (PyModule_AddIntConstant (gdb_module,
>>> "SEC_NO_FLAGS", SEC_NO_FLAGS) < 0 +      ||
>>> PyModule_AddIntConstant (gdb_module, "SEC_ALLOC", SEC_ALLOC) <
>>> 0 +      || PyModule_AddIntConstant (gdb_module, "SEC_LOAD",
>>> SEC_LOAD) < 0 +      || PyModule_AddIntConstant (gdb_module,
>>> "SEC_RELOC", SEC_RELOC) < 0 +      || PyModule_AddIntConstant
>>> (gdb_module, "SEC_READONLY", SEC_READONLY) < 0 +      ||
>>> PyModule_AddIntConstant (gdb_module, "SEC_CODE", SEC_CODE) < 0
>>> +      || PyModule_AddIntConstant (gdb_module, "SEC_DATA",
>>> SEC_DATA) < 0 +      || PyModule_AddIntConstant (gdb_module,
>>> "SEC_ROM", SEC_ROM) < 0 + || PyModule_AddIntConstant
>>> (gdb_module, "SEC_CONSTRUCTOR", + SEC_CONSTRUCTOR) < 0 +
>>> || PyModule_AddIntConstant (gdb_module, "SEC_HAS_CONTENTS", + 
>>> SEC_HAS_CONTENTS) < 0 +      || PyModule_AddIntConstant 
>>> (gdb_module, "SEC_NEVER_LOAD", + SEC_NEVER_LOAD) < 0 +      ||
>>> PyModule_AddIntConstant (gdb_module, "SEC_THREAD_LOCAL", + 
>>> SEC_THREAD_LOCAL) < 0 +      || PyModule_AddIntConstant 
>>> (gdb_module, "SEC_HAS_GOT_REF", + SEC_HAS_GOT_REF) < 0 +
>>> || PyModule_AddIntConstant (gdb_module, "SEC_IS_COMMON", + 
>>> SEC_IS_COMMON) < 0 +      || PyModule_AddIntConstant
>>> (gdb_module, "SEC_DEBUGGING", +
>>> SEC_DEBUGGING) < 0 +      || PyModule_AddIntConstant
>>> (gdb_module, "SEC_IN_MEMORY", +
>>> SEC_IN_MEMORY) < 0 +      || PyModule_AddIntConstant
>>> (gdb_module, "SEC_EXCLUDE", SEC_EXCLUDE) < 0 +      ||
>>> PyModule_AddIntConstant (gdb_module, "SEC_SORT_ENTRIES", + 
>>> SEC_SORT_ENTRIES) < 0 +      || PyModule_AddIntConstant 
>>> (gdb_module, "SEC_LINK_ONCE", + SEC_LINK_ONCE) < 0 +      ||
>>> PyModule_AddIntConstant (gdb_module, "SEC_LINK_DUPLICATES", + 
>>> SEC_LINK_DUPLICATES) < 0 +      || PyModule_AddIntConstant 
>>> (gdb_module, "SEC_LINK_DUPLICATES_DISCARD", + 
>>> SEC_LINK_DUPLICATES_DISCARD) < 0 +      || 
>>> PyModule_AddIntConstant (gdb_module, 
>>> "SEC_LINK_DUPLICATES_ONE_ONLY", + SEC_LINK_DUPLICATES_ONE_ONLY)
>>> < 0 +      || PyModule_AddIntConstant (gdb_module, 
>>> "SEC_LINK_DUPLICATES_SAME_SIZE", + 
>>> SEC_LINK_DUPLICATES_SAME_SIZE) < 0 +      || 
>>> PyModule_AddIntConstant (gdb_module, "SEC_LINKER_CREATED", + 
>>> SEC_LINKER_CREATED) < 0 +      || PyModule_AddIntConstant 
>>> (gdb_module, "SEC_KEEP", SEC_KEEP) < 0 +      || 
>>> PyModule_AddIntConstant (gdb_module, "SEC_SMALL_DATA", + 
>>> SEC_SMALL_DATA) < 0 +      || PyModule_AddIntConstant 
>>> (gdb_module, "SEC_MERGE", SEC_MERGE) < 0 +      || 
>>> PyModule_AddIntConstant (gdb_module, "SEC_STRNGS", SEC_STRINGS)
>>> < 0 +      || PyModule_AddIntConstant (gdb_module,
>>> "SEC_GROUP", SEC_GROUP) < 0 +      || PyModule_AddIntConstant
>>> (gdb_module, "SEC_COFF_SHARED_LIBRARY", + 
>>> SEC_COFF_SHARED_LIBRARY) < 0 +      || PyModule_AddIntConstant 
>>> (gdb_module, "SEC_ELF_REVERSE_COPY", + SEC_ELF_REVERSE_COPY) <
>>> 0 +      || PyModule_AddIntConstant (gdb_module,
>>> "SEC_COFF_SHARED", + SEC_COFF_SHARED) < 0 +      ||
>>> PyModule_AddIntConstant (gdb_module, "SEC_COFF_NOREAD", + 
>>> SEC_COFF_NOREAD) < 0) +    return -1; ...
> 
> 
> 
> 

- -- 
Jeff Mahoney
SUSE Labs
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