From: Nicolas Schier <nsc@kernel.org>
To: Sathvika Vasireddy <sv@linux.ibm.com>
Cc: 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, mahesh@linux.ibm.com
Subject: Re: [RFC PATCH v2 2/3] kbuild: Add objtool integration for PowerPC feature fixups
Date: Sat, 4 Oct 2025 21:43:23 +0200 [thread overview]
Message-ID: <aOF4223Q5egUS_in@levanger> (raw)
In-Reply-To: <20250929080456.26538-3-sv@linux.ibm.com>
On Mon, Sep 29, 2025 at 01:34:55PM +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 +++++++
> arch/Kconfig | 3 +++
> scripts/Makefile.lib | 5 +++--
> scripts/Makefile.vmlinux | 13 ++++++++++++-
> 4 files changed, 25 insertions(+), 3 deletions(-)
>
...
> diff --git a/arch/Kconfig b/arch/Kconfig
> index d1b4ffd6e085..d870aab17cba 100644
> --- a/arch/Kconfig
> +++ b/arch/Kconfig
> @@ -1334,6 +1334,9 @@ config HAVE_UACCESS_VALIDATION
> bool
> select OBJTOOL
>
> +config HAVE_OBJTOOL_FTR_FIXUP
For me, FTR is not that natural to parse. Is there a reason for using
FTR instead of FEATURE?
...
> diff --git a/scripts/Makefile.vmlinux b/scripts/Makefile.vmlinux
> index b64862dc6f08..94cc2bba929a 100644
> --- a/scripts/Makefile.vmlinux
> +++ b/scripts/Makefile.vmlinux
> @@ -84,7 +84,8 @@ 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) \
> + $(cmd_objtool_vmlinux)
>
> targets += $(vmlinux-final)
> $(vmlinux-final): scripts/link-vmlinux.sh vmlinux.o $(KBUILD_LDS) FORCE
> @@ -131,3 +132,13 @@ existing-targets := $(wildcard $(sort $(targets)))
> -include $(foreach f,$(existing-targets),$(dir $(f)).$(notdir $(f)).cmd)
>
> .PHONY: $(PHONY)
> +
> +# objtool for vmlinux
> +# ----------------------------------
> +#
> +# For feature fixup, objtool does not run on individual
> +# translation units. Run this on vmlinux instead.
> +
> +ifdef CONFIG_HAVE_OBJTOOL_FTR_FIXUP
> +cmd_objtool_vmlinux = ; $(objtool) --ftr-fixup --link $@
This cmd_* definition is broken as $(call cmd,objtool_vmlinux) would be
evaluated to '... ; ; ...' (shell syntax error).
What about putting the objtool call right into cmd_link_vmlinux?
cmd_link_vmlinux = \
$< "$(LD)" "$(KBUILD_LDFLAGS)" "$(LDFLAGS_vmlinux)" "$@"; \
$(if $(ARCH_POSTLINK), $(MAKE) -f $(ARCH_POSTLINK) $@, true); \
$(if $(CONFIG_HAVE_OBJTOOL_FTR_FIXUP), $(objtool) --ftr-fixup --link $@, true)
Kind regards,
Nicolas
next prev parent reply other threads:[~2025-10-04 19:44 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-09-29 8:04 [RFC PATCH v2 0/3] objtool: Fixup alternate feature relative addresses Sathvika Vasireddy
2025-09-29 8:04 ` [RFC PATCH v2 1/3] objtool/powerpc: Enhance objtool to fixup " Sathvika Vasireddy
2025-09-29 10:49 ` Peter Zijlstra
2025-09-29 16:59 ` Sathvika Vasireddy
2025-09-29 8:04 ` [RFC PATCH v2 2/3] kbuild: Add objtool integration for PowerPC feature fixups Sathvika Vasireddy
2025-10-04 19:43 ` Nicolas Schier [this message]
2025-09-29 8:04 ` [RFC PATCH v2 3/3] powerpc: Enable build-time feature fixup processing by default Sathvika Vasireddy
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