From: Nicolas Schier <nsc@kernel.org>
To: Sathvika Vasireddy <sv@linux.ibm.com>
Cc: linux-kernel@vger.kernel.org, linux-kbuild@vger.kernel.org,
linuxppc-dev@lists.ozlabs.org, 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
Subject: Re: [RFC PATCH v4 5/6] kbuild: Add objtool integration for PowerPC feature fixups
Date: Mon, 16 Mar 2026 16:52:28 +0100 [thread overview]
Message-ID: <abgnPNNygOs6EnQc@levanger> (raw)
In-Reply-To: <20260316062237.30948-6-sv@linux.ibm.com>
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On Mon, Mar 16, 2026 at 11:52:36AM +0530, Sathvika Vasireddy wrote:
> Add build system support for PowerPC feature fixup processing:
>
> - Add HAVE_OBJTOOL_FTR_FIXUP config option for architectures that support
> build-time feature fixup processing
> - Integrate objtool feature fixup processing into vmlinux build
>
> Suggested-by: Masahiro Yamada <masahiroy@kernel.org>
> Signed-off-by: Sathvika Vasireddy <sv@linux.ibm.com>
> ---
> Makefile | 7 +++++++
> scripts/Makefile.lib | 4 ++--
> scripts/Makefile.vmlinux | 3 ++-
> 3 files changed, 11 insertions(+), 3 deletions(-)
>
> diff --git a/Makefile b/Makefile
> index 83ed80595378..861f5bec655c 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -1467,6 +1467,13 @@ ifdef CONFIG_OBJTOOL
> prepare: tools/objtool
> endif
>
> +# CONFIG_OBJTOOL and CONFIG_HAVE_OBJTOOL_FTR_FIXUP are unrelated, separate
> +# options. It was integrated in objtool in order to borrow the elf parser,
> +# but this is different from how the other objtool commands are used.
> +ifdef CONFIG_HAVE_OBJTOOL_FTR_FIXUP
> +prepare: tools/objtool
> +endif
> +
> ifdef CONFIG_BPF
> ifdef CONFIG_DEBUG_INFO_BTF
> prepare: tools/bpf/resolve_btfids
> diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
> index e429d68b8594..c9478c717574 100644
> --- a/scripts/Makefile.lib
> +++ b/scripts/Makefile.lib
> @@ -179,10 +179,10 @@ cpp_flags = -Wp,-MMD,$(depfile) $(NOSTDINC_FLAGS) $(LINUXINCLUDE) \
>
> ld_flags = $(KBUILD_LDFLAGS) $(ldflags-y) $(LDFLAGS_$(@F))
>
> -ifdef CONFIG_OBJTOOL
> -
> objtool := $(objtree)/tools/objtool/objtool
>
> +ifdef CONFIG_OBJTOOL
> +
> objtool-args-$(CONFIG_HAVE_JUMP_LABEL_HACK) += --hacks=jump_label
> objtool-args-$(CONFIG_HAVE_NOINSTR_HACK) += --hacks=noinstr
> objtool-args-$(CONFIG_MITIGATION_CALL_DEPTH_TRACKING) += --hacks=skylake
> diff --git a/scripts/Makefile.vmlinux b/scripts/Makefile.vmlinux
> index fcae1e432d9a..a1bef0638ecb 100644
> --- a/scripts/Makefile.vmlinux
> +++ b/scripts/Makefile.vmlinux
> @@ -65,7 +65,8 @@ ARCH_POSTLINK := $(wildcard $(srctree)/arch/$(SRCARCH)/Makefile.postlink)
> # Final link of vmlinux with optional arch pass after final link
> cmd_link_vmlinux = \
> $< "$(LD)" "$(KBUILD_LDFLAGS)" "$(LDFLAGS_vmlinux)" "$@"; \
> - $(if $(ARCH_POSTLINK), $(MAKE) -f $(ARCH_POSTLINK) $@, true)
> + $(if $(ARCH_POSTLINK), $(MAKE) -f $(ARCH_POSTLINK) $@, true); \
> + $(if $(CONFIG_HAVE_OBJTOOL_FTR_FIXUP), $(objtool) --ftr-fixup --link $@, true)
>
> targets += vmlinux.unstripped .vmlinux.export.o
> vmlinux.unstripped: scripts/link-vmlinux.sh vmlinux.o .vmlinux.export.o $(KBUILD_LDS) FORCE
> --
> 2.43.0
>
Acked-by: Nicolas Schier <nsc@kernel.org> # kbuild
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next prev parent reply other threads:[~2026-03-16 15:54 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-03-16 6:22 [RFC PATCH v4 0/6] objtool: Fixup alternate feature relative addresses Sathvika Vasireddy
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 [this message]
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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