Christophe Leroy [off-list ref] writes:

PPC64/IA64/PARISC have function descriptors. LKDTM doesn't work
on those three architectures because LKDTM messes up function
descriptors with functions.

Just to nitpick, it's powerpc 64-bit using the ELFv1 ABI. [1]

The ELFv2 ABI [2] doesn't use function descriptors. (ELFv2 is used
primarily for ppc64le, but some people like musl support it for BE as
well.)

This doesn't affect the correctness or desirability of your changes, it
was just bugging me when I was reading the commit messages :-)

Kind regards,
Daniel

[1] See e.g. https://refspecs.linuxfoundation.org/ELF/ppc64/PPC-elf64abi.html
[2] https://openpowerfoundation.org/wp-content/uploads/2016/03/ABI64BitOpenPOWERv1.1_16July2015_pub4.pdf

This series does some cleanup in the three architectures and
refactors function descriptors so that it can then easily use it
in a generic way in LKDTM.

Patch 8 is not absolutely necessary but it is a good trivial cleanup.

Changes in v2:
- Addressed received comments
- Moved dereference_[kernel]_function_descriptor() out of line
- Added patches to remove func_descr_t and func_desc_t in powerpc
- Using func_desc_t instead of funct_descr_t
- Renamed HAVE_DEREFERENCE_FUNCTION_DESCRIPTOR to HAVE_FUNCTION_DESCRIPTORS
- Added a new lkdtm test to check protection of function descriptors

Christophe Leroy (13):
  powerpc: Move 'struct ppc64_opd_entry' back into asm/elf.h
  powerpc: Rename 'funcaddr' to 'addr' in 'struct ppc64_opd_entry'
  powerpc: Remove func_descr_t
  powerpc: Prepare func_desc_t for refactorisation
  ia64: Rename 'ip' to 'addr' in 'struct fdesc'
  asm-generic: Use HAVE_FUNCTION_DESCRIPTORS to define associated stubs
  asm-generic: Define 'func_desc_t' to commonly describe function
    descriptors
  asm-generic: Refactor dereference_[kernel]_function_descriptor()
  lkdtm: Force do_nothing() out of line
  lkdtm: Really write into kernel text in WRITE_KERN
  lkdtm: Fix lkdtm_EXEC_RODATA()
  lkdtm: Fix execute_[user]_location()
  lkdtm: Add a test for function descriptors protection

 arch/ia64/include/asm/elf.h              |  2 +-
 arch/ia64/include/asm/sections.h         | 25 ++-------
 arch/ia64/kernel/module.c                |  6 +--
 arch/parisc/include/asm/sections.h       | 17 +++---
 arch/parisc/kernel/process.c             | 21 --------
 arch/powerpc/include/asm/code-patching.h |  2 +-
 arch/powerpc/include/asm/elf.h           |  6 +++
 arch/powerpc/include/asm/sections.h      | 30 ++---------
 arch/powerpc/include/asm/types.h         |  6 ---
 arch/powerpc/include/uapi/asm/elf.h      |  8 ---
 arch/powerpc/kernel/module_64.c          | 38 +++++--------
 arch/powerpc/kernel/signal_64.c          |  8 +--
 drivers/misc/lkdtm/core.c                |  1 +
 drivers/misc/lkdtm/lkdtm.h               |  1 +
 drivers/misc/lkdtm/perms.c               | 68 ++++++++++++++++++++----
 include/asm-generic/sections.h           | 13 ++++-
 include/linux/kallsyms.h                 |  2 +-
 kernel/extable.c                         | 23 +++++++-
 18 files changed, 138 insertions(+), 139 deletions(-)

-- 
2.31.1