The following commit has been merged into the objtool/core branch of tip:
Commit-ID: 8852c552402979508fdc395ae07aa8761aa46045
Gitweb: https://git.kernel.org/tip/8852c552402979508fdc395ae07aa8761aa46045
Author: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
AuthorDate: Tue, 18 May 2021 18:59:15 -05:00
Committer: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
CommitterDate: Wed, 19 May 2021 15:07:20 -05:00
kbuild: Fix objtool dependency for 'OBJECT_FILES_NON_STANDARD_<obj> := n'
"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@xxxxxxxxxxxxx>
Signed-off-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
---
scripts/Makefile.build | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index 949f723..34d2576 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -268,7 +268,8 @@ 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) $$(objtool_dep) FORCE
$(call if_changed_rule,cc_o_c)
$(call cmd,force_checksrc)
@@ -349,7 +350,7 @@ cmd_modversions_S = \
fi
endif
-$(obj)/%.o: $(src)/%.S $(objtool_dep) FORCE
+$(obj)/%.o: $(src)/%.S $$(objtool_dep) FORCE
$(call if_changed_rule,as_o_S)
targets += $(filter-out $(subdir-builtin), $(real-obj-y))
|