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.
[1] Original PowerPC tool approach:
http://patchwork.ozlabs.org/project/linuxppc-dev/patch/[email protected]/
Testing:
Build and Boot tested on ppc64le, ppc64be, and ppc32be configs.
Sathvika Vasireddy (6):
objtool/powerpc: Add build-time fixup of alternate feature branch
targets
objtool: Set ELF_F_LAYOUT flag to preserve vmlinux segment layout
objtool: Fix "can't find starting instruction" warnings on vmlinux
objtool/powerpc: Skip jump destination analysis and unnanotated
intra-function call warnings for --ftr-fixup
kbuild: Add objtool integration for PowerPC feature fixups
powerpc: Enable build-time feature fixup processing by default
--
Changes since v1:
https://lore.kernel.org/all/[email protected]/
- rebase to upstream master
- 1/6: in arch_decode_instruction() added comment describing opcode 16.
- 1/6: in arch_decode_instruction() added missing logic to add AA flag to
offset.
Changes since RFC-v4:
https://lore.kernel.org/all/[email protected]/
- 4/6: In the instruction validation logic, update insn_call_dest() handling
to allow unannotated intra-function calls when opts.ftr_fixup is enabled,
and continue processing the instruction.
- 3/6: In the function processing logic, skip zero-length symbols before
performing function boundary validation, as suggested by Sashiko.
- 3/6: In the function processing loop, add func_off to track the
absolute/local offset and replace sym_for_each_insn() with an explicit
loop.
- 1/6: In process_alt_data(), skip files that do not use opt.link.
- 1/6: In process_fixup_entries(), handle realloc() failure and return
-1` when allocation fails.
- 1/6: In check_and_flatten_fixup_entries(), remove dead code that
redundantly resets the fixup entry parent.
- 1/6: In is_local_symbol(), fix the local-symbol detection logic and add
a comment explaining the new check.
- 1/6: In process_alt_relocations(), check that ftr_alt->data and
ftr->data->d_buf are initialized before accessing them.
- 1/6: Remove redundant line deletions and perform minor cleanup.
Changes in V4:
- consolidate emit-relocs remove-section logic for
CONFIG_ARCH_VMLINUX_NEEDS_RELOCS and CONFIG_HAVE_OBJTOOL_FTR_FIXUP
configs as suggested by Nathan Chancellor.
Changes in V3:
- Split code into individual patches
- Put objtool call into cmd_link_vmlinux
- Move HAVE_OBJTOOL_FEATURE_FIXUP from arch/Kconfig to
arch/powerpc/Kconfig
Changes in V2:
- Added implementation support for ppc64 LE, BE, ppc32 BE.
---
Makefile | 7 +
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 | 4 +-
scripts/Makefile.vmlinux | 11 +-
tools/objtool/arch/powerpc/decode.c | 11 +
tools/objtool/arch/powerpc/special.c | 451 ++++++++++++++++++++++
tools/objtool/builtin-check.c | 2 +
tools/objtool/check.c | 55 ++-
tools/objtool/elf.c | 3 +
tools/objtool/include/objtool/builtin.h | 1 +
tools/objtool/include/objtool/special.h | 56 +++
tools/objtool/special.c | 29 ++
16 files changed, 632 insertions(+), 28 deletions(-)
--
2.54.0
