Re: [PATCH v1 7/7] tools: add userspace linker table sandbox

["H. Peter Anvin" <hpa@zytor.com>]

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Message-ID: <58F06CEA-AEB3-4ED7-8211-95F402C9D3D3@zytor.com>

On August 22, 2016 5:07:39 PM PDT, "Luis R. Rodriguez" <mcgrof@kernel.org> wrote:
>On Fri, Aug 19, 2016 at 03:31:47PM -0700, Kees Cook wrote:
>> On Fri, Aug 19, 2016 at 2:41 PM,  <mcgrof@kernel.org> wrote:
>> > From: "Luis R. Rodriguez" <mcgrof@kernel.org>
>> >
>> > Add a userspace sandbox to allow easy experimentation and
>> > test extensions with linker tables, section ranges and the
>> > new section core definitions.
>> >
>> > The userspace sandbox tries to mimic the Linux kernel development
>> > flow as much as possible, it however relies on and uses libc.
>Support
>> > is currently only provided to x86_64.
>> >
>> > v4: this patch is new in this series -- added to the kenrel as
>> >     suggested by Boris, as otherwise it'd be really hard to keep
>> >     an external userspace repository in sync.
>> >
>> > Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org>
>> > ---
>> >  Documentation/sections/linker-tables.rst           |   4 +-
>> >  MAINTAINERS                                        |   1 +
>> >  include/linux/tables.h                             |   5 +-
>> >  tools/Makefile                                     |   3 +-
>> >  .../arch/x86/include/generated/asm/section-core.h  |   1 +
>> >  tools/arch/x86/include/generated/ranges.h          |   1 +
>> >  tools/arch/x86/include/generated/tables.h          |   1 +
>> >  tools/include/asm-generic/ranges.h                 | 103 ++++
>> >  tools/include/asm-generic/section-core.h           | 341
>+++++++++++
>> >  tools/include/asm-generic/tables.h                 |  50 ++
>> 
>> Aren't a bunch of these files exact duplicates of the headers in
>include/linux?
>
>Indeed... This a userspace tools/ architecture decision that was made
>long ago,
>so its not up to me, I am just following the strategy devised and
>picked up.
>Refer to 7d7d1bf1d1dabe435ef50efb051724b8664749cb ("perf bench: Copy
>kernel
>files needed to build mem{cpy,set} x86_64 benchmarks") for an example
>of
>previous similar work. By sharing header files this enable more tools/
>to be hacked on.
>
>  Luis

I think this is a legacy from before the uapi change that should really be fixed.  If we need to export additional kernel structures for the tools, we could define a third level of we really need it.
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