[PATCH v2 06/13] kbuild: reuse $(cmd_objtool) for cmd_cc_lto_link_modules

Masahiro Yamada
2021-08-31T07:40:57Z

For CONFIG_LTO_CLANG=y, the objtool processing is not possible at the
compilation, hence postponed by the link time.

Reuse $(cmd_objtool) for CONFIG_LTO_CLANG=y by defining objtool-enabled
properly.

For CONFIG_LTO_CLANG=y:

objtool-enabled is off for %.o compilation
objtool-enabled is on for %.lto link

For CONFIG_LTO_CLANG=n:

objtool-enabled is on for %.o compilation
(but, it depends on OBJECT_FILE_NON_STANDARD)

Set part-of-module := y for %.lto.o to avoid repeating --module.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
---

scripts/Makefile.build | 28 +++++++++++++++++-----------
1 file changed, 17 insertions(+), 11 deletions(-)

diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index 21b55f37a23f..afc906cd7256 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -236,20 +236,26 @@ objtool_args = \
$(if $(CONFIG_X86_SMAP), --uaccess) \
$(if $(CONFIG_FTRACE_MCOUNT_USE_OBJTOOL), --mcount)

-ifndef CONFIG_LTO_CLANG
+cmd_objtool = $(if $(objtool-enabled), ; $(objtool) $(objtool_args) $@)
+cmd_gen_objtooldep = $(if $(objtool-enabled), { echo ; echo '$@: $$(wildcard $(objtool))' ; } >> $(dot-target).cmd)
+
+endif # CONFIG_STACK_VALIDATION
+
+ifdef CONFIG_LTO_CLANG
+
+# Skip objtool for LLVM bitcode
+$(obj)/%o: objtool-enabled :=
+
+else

# 'OBJECT_FILES_NON_STANDARD := y': skip objtool checking for a directory
# 'OBJECT_FILES_NON_STANDARD_foo.o := 'y': skip objtool checking for a file
# 'OBJECT_FILES_NON_STANDARD_foo.o := 'n': override directory skip for a file

-objtool-enabled = $(if $(filter-out y%, \
+$(obj)/%o: objtool-enabled = $(if $(filter-out y%, \
$(OBJECT_FILES_NON_STANDARD_$(basetarget).o)$(OBJECT_FILES_NON_STANDARD)n),y)

-cmd_objtool = $(if $(objtool-enabled), ; $(objtool) $(objtool_args) $@)
-cmd_gen_objtooldep = $(if $(objtool-enabled), { echo ; echo '$@: $$(wildcard $(objtool))' ; } >> $(dot-target).cmd)
-
-endif # CONFIG_LTO_CLANG
-endif # CONFIG_STACK_VALIDATION
+endif

ifdef CONFIG_TRIM_UNUSED_KSYMS
cmd_gen_ksymdeps = \
@@ -289,13 +295,13 @@ cmd_cc_lto_link_modules = \
$(LD) $(ld_flags) -r -o $@ \
$(shell [ -s $(@:.lto.o=.o.symversions) ] && \
echo -T $(@:.lto.o=.o.symversions)) \
- --whole-archive $(filter-out FORCE,$^)
+ --whole-archive $(filter-out FORCE,$^) \
+ $(cmd_objtool)

-ifdef CONFIG_STACK_VALIDATION
# objtool was skipped for LLVM bitcode, run it now that we have compiled
# modules into native code
-cmd_cc_lto_link_modules += ; $(objtool) $(objtool_args) --module $@
-endif
+$(obj)/%.lto.o: objtool-enabled = y
+$(obj)/%.lto.o: part-of-module := y

$(obj)/%.lto.o: $(obj)/%.o FORCE
$(call if_changed,cc_lto_link_modules)
--
2.30.2