[RFC PATCH v2 0/3] objtool: Fixup alternate feature relative addresses

[Sathvika Vasireddy]

This patch series implements build-time fixup of alternate feature
relative addresses for powerpc.

Previously, Nicholas Piggin proposed a build-time solution using a
custom PowerPC tool [1], which provided the foundation for this approach.
The current implementation leverages objtool's existing ELF parsing
infrastructure to do the same.

This patchset applies atop powerpc/merge branch.

Links and History:
[1] Original PowerPC tool approach:
    http://patchwork.ozlabs.org/project/linuxppc-dev/patch/20170521010130.13552-1-npiggin@gmail.com/
[2] Initial RFC v1:
    https://lore.kernel.org/linuxppc-dev/20240422092206.147078-1-sv@linux.ibm.com/T/#t
[3] PowerPC instruction decoder borrowed from:
    https://lore.kernel.org/linuxppc-dev/bfa8364da047d8610a09458a1cd924a0566aedbb.1736955567.git.christophe.leroy@csgroup.eu/#Z31tools:objtool:arch:powerpc:decode.c

Testing:
Build and Boot tested on ppc64le, ppc64be, and ppc32be configs.

Changes in V2:
- Added implementation support for ppc64 LE, BE, ppc32 BE.

Sathvika Vasireddy (3):
  objtool/powerpc: Enhance objtool to fixup alternate feature relative
    addresses
  kbuild: Add objtool integration for PowerPC feature fixups
  powerpc: Enable build-time feature fixup processing by default

 Makefile                                  |   7 +
 arch/Kconfig                              |   3 +
 arch/powerpc/Kconfig                      |   3 +
 arch/powerpc/Makefile                     |   5 +
 arch/powerpc/include/asm/feature-fixups.h |   2 +-
 arch/powerpc/kernel/vmlinux.lds.S         |   8 +-
 arch/powerpc/lib/feature-fixups.c         |  12 -
 scripts/Makefile.lib                      |   5 +-
 scripts/Makefile.vmlinux                  |  13 +-
 tools/objtool/arch/powerpc/decode.c       |  15 +-
 tools/objtool/arch/powerpc/special.c      | 436 ++++++++++++++++++++++
 tools/objtool/builtin-check.c             |   2 +
 tools/objtool/check.c                     |  48 ++-
 tools/objtool/elf.c                       |   4 +
 tools/objtool/include/objtool/builtin.h   |   1 +
 tools/objtool/include/objtool/special.h   |  56 +++
 16 files changed, 593 insertions(+), 27 deletions(-)

-- 
2.43.0