From: Sathvika Vasireddy <sv@linux•ibm.com>
To: linux-kernel@vger•kernel.org, linux-kbuild@vger•kernel.org,
linuxppc-dev@lists•ozlabs.org
Cc: nathan@kernel•org, masahiroy@kernel•org, kees@kernel•org,
naveen@kernel•org, jpoimboe@kernel•org, peterz@infradead•org,
npiggin@gmail•com, maddy@linux•ibm.com,
segher@kernel•crashing.org, christophe.leroy@csgroup•eu,
mingo@kernel•org, mpe@ellerman•id.au, sv@linux•ibm.com,
nsc@kernel•org
Subject: [RFC PATCH v4 0/6] objtool: Fixup alternate feature relative addresses
Date: Mon, 16 Mar 2026 11:52:31 +0530 [thread overview]
Message-ID: <20260316062237.30948-1-sv@linux.ibm.com> (raw)
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 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.
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
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
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 | 15 +-
tools/objtool/arch/powerpc/special.c | 437 ++++++++++++++++++++++
tools/objtool/builtin-check.c | 2 +
tools/objtool/check.c | 42 ++-
tools/objtool/elf.c | 4 +
tools/objtool/include/objtool/builtin.h | 1 +
tools/objtool/include/objtool/special.h | 56 +++
tools/objtool/special.c | 29 ++
16 files changed, 612 insertions(+), 26 deletions(-)
--
2.43.0
next reply other threads:[~2026-03-16 6:26 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-03-16 6:22 Sathvika Vasireddy [this message]
2026-03-16 6:22 ` [RFC PATCH v4 1/6] objtool/powerpc: Add build-time fixup of alternate feature branch targets Sathvika Vasireddy
2026-03-16 6:22 ` [RFC PATCH v4 2/6] objtool: Set ELF_F_LAYOUT flag to preserve vmlinux segment layout Sathvika Vasireddy
2026-03-16 6:22 ` [RFC PATCH v4 3/6] objtool: Fix "can't find starting instruction" warnings on vmlinux Sathvika Vasireddy
2026-03-16 6:22 ` [RFC PATCH v4 4/6] objtool/powerpc: Skip jump destination analysis and unnanotated intra-function call warnings for --ftr-fixup Sathvika Vasireddy
2026-03-16 6:22 ` [RFC PATCH v4 5/6] kbuild: Add objtool integration for PowerPC feature fixups Sathvika Vasireddy
2026-03-16 15:52 ` Nicolas Schier
2026-03-16 6:22 ` [RFC PATCH v4 6/6] powerpc: Enable build-time feature fixup processing by default Sathvika Vasireddy
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