[PATCH v2 2/2] kbuild: policy: support out-of-tree builds for external policy files

[Sascha Hauer <s.hauer@pengutronix.de>]

So far the sconfig files were required to be in the source tree which
was a deliberate decision because we wanted the sconfig files to be
committed. With barebox integrated into build systems the sconfig files
are most of the time stored in the build system anyway, so having
them in the source tree is unnecessary and just prevents sharing the
barebox source tree between different builds.

Change this by:
- Using resolve-external instead of resolve-srctree when copying
  .sconfig.tmp files back after security_%config
- Adding a .sconfig.tmp rule in Makefile.policy analogous to the
  existing .config.tmp rule
- Searching both srctree and objtree for external policy files in
  security/Makefile and resolving the correct path for dependencies

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Link: https://lore.barebox.org/20260225153057.3199724-2-s.hauer@pengutronix.de
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
---
 Makefile                | 2 +-
 scripts/Makefile.policy | 7 +++++++
 security/Makefile       | 9 ++++++---
 3 files changed, 14 insertions(+), 4 deletions(-)

diff --git a/Makefile b/Makefile
index 4bf77896b6..a5b2543900 100644
--- a/Makefile
+++ b/Makefile
@@ -1258,7 +1258,7 @@ security_%config: collect-policies FORCE
 		$(@:security_%=%),$p.tmp))
 ifeq ($(KPOLICY_TMPUPDATE),)
 	+$(Q)$(foreach p, $(KPOLICY), \
-		cp 2>/dev/null $p.tmp $(call resolve-srctree,$p) || true;)
+		cp 2>/dev/null $p.tmp $(call resolve-external,$p) || true;)
 endif
 
 quiet_cmd_sconfigpost = SCONFPP $@
diff --git a/scripts/Makefile.policy b/scripts/Makefile.policy
index f2c6b204d5..12aa920c04 100644
--- a/scripts/Makefile.policy
+++ b/scripts/Makefile.policy
@@ -80,6 +80,13 @@ else
 	$(call if_changed,shipped)
 endif
 
+$(obj)/%.sconfig.tmp: $(obj)/%.sconfig FORCE
+ifeq ($(KPOLICY_TMPUPDATE),)
+	$(call filechk,cat)
+else
+	$(call if_changed,shipped)
+endif
+
 quiet_cmd_sconfigpost_c = SCONFPP $@
       cmd_sconfigpost_c = $(SCONFIGPOST) -o $@ -D$(depfile) $(2)
 
diff --git a/security/Makefile b/security/Makefile
index 1096cbfb9b..510fe5af65 100644
--- a/security/Makefile
+++ b/security/Makefile
@@ -52,12 +52,15 @@ $(foreach p, $(external-policy), \
 	CONFIG_SECURITY_POLICY_PATH contains path separators.\
 	$(newline)"$p" must start with security/)))
 $(foreach p, $(external-policy), \
-	$(if $(wildcard $(srctree)/$(src)/$p),,$(error \
+	$(if $(or $(wildcard $(srctree)/$(src)/$p),$(wildcard $(objtree)/$(src)/$p)),,$(error \
 	CONFIG_SECURITY_POLICY_PATH contains non-existent files.\
-	$(newline)"$p" does not exist in $$(srctree)/security)))
+	$(newline)"$p" does not exist in $$(srctree)/security or $$(objtree)/security)))
 endif
 
-$(obj)/policy-list: $(addprefix $(src)/,$(external-policy)) FORCE
+external-policy-src = $(foreach p,$(external-policy),\
+    $(if $(wildcard $(srctree)/$(src)/$p),$(src)/$p,$(obj)/$p))
+
+$(obj)/policy-list: $(external-policy-src) FORCE
 	$(call if_changed,gen_order_src)
 
 targets += $(external-policy-tmp)

-- 
2.47.3