| From 2d5462f93ca5c0357bf761aa11cf47c9b2c9062b Mon Sep 17 00:00:00 2001 |
| From: Sasha Levin <sashal@kernel.org> |
| Date: Tue, 18 May 2021 18:59:15 -0500 |
| Subject: kbuild: Fix objtool dependency for 'OBJECT_FILES_NON_STANDARD_<obj> |
| := n' |
| |
| 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 4c058f12dd73..8bd4e673383f 100644 |
| --- a/scripts/Makefile.build |
| +++ b/scripts/Makefile.build |
| @@ -275,7 +275,8 @@ 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) $$(objtool_dep) FORCE |
| $(call if_changed_rule,cc_o_c) |
| $(call cmd,force_checksrc) |
| |
| @@ -356,7 +357,7 @@ cmd_modversions_S = \ |
| fi |
| endif |
| |
| -$(obj)/%.o: $(src)/%.S $(objtool_dep) FORCE |
| +$(obj)/%.o: $(src)/%.S $$(objtool_dep) FORCE |
| $(call if_changed_rule,as_o_S) |
| |
| targets += $(filter-out $(subdir-builtin), $(real-obj-y)) |
| -- |
| 2.30.2 |
| |
