[PATCH v7 8/8] kbuild: rebuild multi-object modules when objtool is updated

[Masahiro Yamada]

When CONFIG_LTO_CLANG or CONFIG_X86_KERNEL_IBT is enabled, objtool for
multi-object modules is postponed until the objects are linked together.

Make sure to re-run objtool and re-link multi-object modules when
objtool is updated.

Signed-off-by: Masahiro Yamada <masahiroy@xxxxxxxxxx>
Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx>
Acked-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
Tested-by: Nathan Chancellor <nathan@xxxxxxxxxx>
Reviewed-by: Nicolas Schier <n.schier@xxxxxx>
Tested-by: Sedat Dilek <sedat.dilek@xxxxxxxxx> # LLVM-14 (x86-64)
---

(no changes since v4)

Changes in v4:
  - New
    Resent of my previous submission
    https://lore.kernel.org/linux-kbuild/20210831074004.3195284-11-masahiroy@xxxxxxxxxx/

 scripts/Makefile.build | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index 31feb798e16e..bd5fc2b37387 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -412,13 +412,18 @@ $(obj)/modules.order: $(obj-m) FORCE
 $(obj)/lib.a: $(lib-y) FORCE
 	$(call if_changed,ar)
 
-quiet_cmd_link_multi-m = LD [M]  $@
-      cmd_link_multi-m = $(LD) $(ld_flags) -r -o $@ @$(patsubst %.o,%.mod,$@) $(cmd_objtool)
+quiet_cmd_ld_multi_m = LD [M]  $@
+      cmd_ld_multi_m = $(LD) $(ld_flags) -r -o $@ @$(patsubst %.o,%.mod,$@) $(cmd_objtool)
+
+define rule_ld_multi_m
+	$(call cmd_and_savecmd,ld_multi_m)
+	$(call cmd,gen_objtooldep)
+endef
 
 $(multi-obj-m): objtool-enabled := $(delay-objtool)
 $(multi-obj-m): part-of-module := y
 $(multi-obj-m): %.o: %.mod FORCE
-	$(call if_changed,link_multi-m)
+	$(call if_changed_rule,ld_multi_m)
 $(call multi_depend, $(multi-obj-m), .o, -objs -y -m)
 
 targets := $(filter-out $(PHONY), $(targets))
-- 
2.32.0