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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Hi Nicolas, Thank you for the review and suggestions! On 10/5/25 1:13 AM, Nicolas Schier wrote: > 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 >> Signed-off-by: Sathvika Vasireddy >> --- >> 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? The naming comes from the PowerPC-specific section names (__ftr_alt_*) , and (*ftr_fixup) in vmlinux. However, I agree that FEATURE is more readable and I'll update all references to use FEATURE_FIXUP instead. Also, on a second thought, since feature fixup is PowerPC-specific and no other architecture has this mechanism (please correct me if I am wrong), I will move HAVE_OBJTOOL_FEATURE_FIXUP from arch/Kconfig to arch/powerpc/Kconfig in the next version. > > ... >> 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? Sure, I will include the changes to put the objtool call into cmd_link_vmlinux as suggested, in the next version. Thanks, Sathvika --------------Fj4r01fWpXDXE01FndrJSVh0 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: 7bit

Hi Nicolas,

Thank you for the review and suggestions!

On 10/5/25 1:13 AM, Nicolas Schier wrote:
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?

The naming comes from the PowerPC-specific section names (__ftr_alt_*) , and (*ftr_fixup) in vmlinux. However, I agree that FEATURE is more readable and I'll update all references to use FEATURE_FIXUP instead.

Also, on a second thought, since feature fixup is PowerPC-specific and no other architecture has this mechanism (please correct me if I am wrong), I will move HAVE_OBJTOOL_FEATURE_FIXUP from arch/Kconfig to arch/powerpc/Kconfig in the next version.


...

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?

Sure, I will include the changes to put the objtool call into cmd_link_vmlinux as suggested, in the next version.

Thanks, Sathvika --------------Fj4r01fWpXDXE01FndrJSVh0--