Re: [PATCH] [RFC] making uapi/linux/elfcore.h useful again

* Arnd Bergmann [off-list ref] wrote:

After finding a bug in glibc the question came up how linux/elfcore.h
is supposed to be used from user space. As far as I can tell, it's
not possible, as it references data types that are simply unavailable
there.

The #ifndef __KERNEL__ section in that header dates back to when the
file was introduced in linux-1.3.5, and presumably was meant to
provide the structures for the libc sys/procfs.h implementation.
However, this was never portable to architectures other than x86-32,
and has been broken on that architecture at a later point.

These are the steps that I needed to make it possible to include the
header file, e.g. for libc self-testing in order to make sure the
structures are compatible with its own:

- drop the #ifndef __KERNEL__ section that are obviously useless
  and get in the way

- change the pid_t references to __kernel_pid_t

- Move required data from the private x86 asm/elf.h file into
  a new uapi/asm/elf.h. Some other architectures already do that,
  but most of them do not. Before applying the patch, we have
  to do this for all architectures

- Change ELF_NGREG to an integer literal constant instead of
  a sizeof operation based on a private type.

Cc: Joseph Myers <redacted>
Cc: David Howells <dhowells@redhat.com>
Cc: libc-alpha@sourceware.org
Link: https://patchwork.ozlabs.org/patch/969540/
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 arch/x86/include/asm/elf.h         | 24 +-----------------------
 arch/x86/include/uapi/asm/elf.h    | 30 ++++++++++++++++++++++++++++++
 arch/x86/include/uapi/asm/signal.h |  2 +-
 include/uapi/linux/elf.h           |  1 +
 include/uapi/linux/elfcore.h       | 26 +++++---------------------
 5 files changed, 38 insertions(+), 45 deletions(-)
 create mode 100644 arch/x86/include/uapi/asm/elf.h

Acked-by: Ingo Molnar <mingo@kernel.org>

I suspect this wants to go through -mm, or do you want to carry it?

Thanks,

	Ingo