[PATCH 0/8] LoongArch: Add livepatch build (KLP) support

[George Guo <dongtai.guo@linux.dev>]

From: George Guo <guodongtai@kylinos.cn>

This series adds LoongArch support for the klp-build livepatch tooling,
enabling automated livepatch module generation using objtool on
LoongArch.

It is based on Josh Poimboeuf's klp-build series [1] (see base-commit
below) and extends it with the LoongArch-specific objtool and build
pieces, plus a few LoongArch toolchain/relocation fixes required to make
livepatch modules load and run correctly.

Overview:

 - Patch 1 wires up LoongArch klp-build (objtool-based livepatch module
   generation).
 - Patches 2-3 add the objtool bits LoongArch needs: arch_adjusted_addend()
   and the special section entry sizes (.altinstructions, __ex_table,
   __bug_table, __jump_table) so objtool can process livepatch modules.
 - Patches 4-5 fix kernel panics seen when loading livepatch modules,
   caused by LoongArch code-generation/relocation assumptions:
     * disable -mdirect-extern-access for klp builds (the module loader
       relies on GOT entries for external symbol references),
     * force -fPIC so same-compilation-unit symbol references relocate
       correctly.
 - Patch 6 fix EFI linking when building with -fdata-sections.
 - Patch 7 implements arch_jump_opcode_bytes() so klp checksums for
   jump/call instructions are position-independent, mirroring x86/arm64.
 - Patch 8 adds KLP_SYSCALL_DEFINEx() support for LoongArch.

Testing:
 - objtool builds cleanly for LoongArch.
 - Livepatch modules were generated and loaded on a LoongArch machine;
   the panics addressed by patches 4-5 no longer reproduce.

[1] https://git.kernel.org/pub/scm/linux/kernel/git/jpoimboe/linux.git/log/?h=klp-build-arm64

George Guo (8):
  LoongArch: Add livepatch build (KLP) support
  objtool/LoongArch: Add arch_adjusted_addend() for KLP support
  LoongArch: Add special section entry sizes for KLP support
  livepatch/klp-build: disable direct-extern-access for LoongArch to fix
    kernel panic
  LoongArch: fix kernel panic with -fPIC for same-compilation-unit
    symbol references
  LoongArch: Fix EFI linking with -fdata-sections
  objtool/klp: Add LoongArch jump opcode bytes support
  klp-build: Add LoongArch syscall patching macro

 arch/loongarch/Kconfig                       |  1 +
 arch/loongarch/include/asm/alternative-asm.h |  5 ++-
 arch/loongarch/include/asm/alternative.h     |  6 ++-
 arch/loongarch/include/asm/asm-extable.h     | 10 ++++-
 arch/loongarch/include/asm/bug.h             | 15 ++++++-
 arch/loongarch/include/asm/jump_label.h      |  9 +++-
 arch/loongarch/kernel/asm-offsets.c          | 36 +++++++++++++++
 arch/loongarch/kernel/head.S                 |  1 +
 arch/loongarch/kernel/vmlinux.lds.S          |  2 +-
 include/linux/livepatch_helpers.h            | 22 ++++++++++
 scripts/livepatch/klp-build                  | 16 ++++++-
 tools/objtool/Makefile                       |  3 +-
 tools/objtool/arch/loongarch/decode.c        | 46 ++++++++++++++++++++
 13 files changed, 161 insertions(+), 11 deletions(-)


base-commit: 85afaba140a4b9f20fe8c8a64b24fc85f022d981
-- 
2.25.1