From: Josh Poimboeuf jpoimboe@redhat.com
[ Upstream commit 8852c552402979508fdc395ae07aa8761aa46045 ]
"OBJECT_FILES_NON_STANDARD_vma.o := n" has a dependency bug. When objtool source is updated, the affected object doesn't get re-analyzed by objtool.
Peter's new variable-sized jump label feature relies on objtool rewriting the object file. Otherwise the system can fail to boot. That effectively upgrades this minor dependency issue to a major bug.
The problem is that variables in prerequisites are expanded early, during the read-in phase. The '$(objtool_dep)' variable indirectly uses '$@', which isn't yet available when the target prerequisites are evaluated.
Use '.SECONDEXPANSION:' which causes '$(objtool_dep)' to be expanded in a later phase, after the target-specific '$@' variable has been defined.
Fixes: b9ab5ebb14ec ("objtool: Add CONFIG_STACK_VALIDATION option") Fixes: ab3257042c26 ("jump_label, x86: Allow short NOPs") Reported-by: Matthew Wilcox willy@infradead.org Signed-off-by: Josh Poimboeuf jpoimboe@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- scripts/Makefile.build | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/scripts/Makefile.build b/scripts/Makefile.build index 03df22412f86..1261f75cb4e7 100644 --- a/scripts/Makefile.build +++ b/scripts/Makefile.build @@ -257,7 +257,8 @@ define rule_as_o_S endef
# Built-in and composite module parts -$(obj)/%.o: $(src)/%.c $(recordmcount_source) $(objtool_dep) FORCE +.SECONDEXPANSION: +$(obj)/%.o: $(src)/%.c $(recordmcount_source) $$(objtool_dep) FORCE $(call if_changed_rule,cc_o_c) $(call cmd,force_checksrc)
@@ -340,7 +341,7 @@ cmd_modversions_S = \ fi endif
-$(obj)/%.o: $(src)/%.S $(objtool_dep) FORCE +$(obj)/%.o: $(src)/%.S $$(objtool_dep) FORCE $(call if_changed_rule,as_o_S)
targets += $(filter-out $(subdir-obj-y), $(real-obj-y)) $(real-obj-m) $(lib-y)