[PATCH v5 14/14] kbuild: make CONFIG_MODULE_HASHES compatible with module stripping

["Thomas Weißschuh" <linux@weissschuh.net>]

CONFIG_MODULE_HASHES needs to process the modules at build time in the
exact form they will be loaded at runtime. If the modules are stripped
afterwards they will not be loadable anymore.

Also evaluate INSTALL_MOD_STRIP at build time and build the hashes based
on modules stripped this way.

If users specify inconsistent values of INSTALL_MOD_STRIP between build
and installation time, an error is reported.

Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
---
 .gitignore                | 1 +
 kernel/module/Kconfig     | 5 +++++
 scripts/Makefile.modfinal | 9 +++++++++
 scripts/Makefile.modinst  | 4 ++--
 scripts/Makefile.vmlinux  | 2 +-
 5 files changed, 18 insertions(+), 3 deletions(-)

diff --git a/.gitignore b/.gitignore
index 78cf799401e6..6ce10623c5a3 100644
--- a/.gitignore
+++ b/.gitignore
@@ -30,6 +30,7 @@
 *.gz
 *.i
 *.ko
+*.ko.stripped
 *.lex.c
 *.ll
 *.lst
diff --git a/kernel/module/Kconfig b/kernel/module/Kconfig
index acbbda58e7c8..48be498a4452 100644
--- a/kernel/module/Kconfig
+++ b/kernel/module/Kconfig
@@ -423,6 +423,11 @@ config MODULE_HASHES
 
 	  Also see the warning in MODULE_SIG about stripping modules.
 
+# To validate the consistency of INSTALL_MOD_STRIP for MODULE_HASHES
+config MODULE_INSTALL_STRIP
+	string
+	default "$(INSTALL_MOD_STRIP)"
+
 config MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS
 	bool "Allow loading of modules with missing namespace imports"
 	help
diff --git a/scripts/Makefile.modfinal b/scripts/Makefile.modfinal
index 44a382689a5a..9924a7bb73c5 100644
--- a/scripts/Makefile.modfinal
+++ b/scripts/Makefile.modfinal
@@ -64,7 +64,16 @@ ifdef CONFIG_DEBUG_INFO_BTF_MODULES
 endif
 	+$(call cmd,check_tracepoint)
 
+%.ko.stripped: %.ko $(wildcard include/config/MODULE_INSTALL_STRIP)
+	$(call cmd,install_mod)
+	$(call cmd,strip_mod)
+
+ifneq ($(CONFIG_MODULE_INSTALL_STRIP),)
+modules.order: $(modules:%.o=%.ko.stripped)
+endif
+
 targets += $(modules:%.o=%.ko) $(modules:%.o=%.mod.o) .module-common.o
+targets += $(modules:%.o=%.ko.stripped)
 
 # Update modules.order when a module is (re-)built.
 # Allow using it as target dependency.
diff --git a/scripts/Makefile.modinst b/scripts/Makefile.modinst
index b95f613e23c8..fd1fb89bb0bd 100644
--- a/scripts/Makefile.modinst
+++ b/scripts/Makefile.modinst
@@ -68,8 +68,8 @@ __modinst: $(install-y)
 
 ifdef CONFIG_MODULE_HASHES
 ifeq ($(KBUILD_EXTMOD),)
-ifdef INSTALL_MOD_STRIP
-$(error CONFIG_MODULE_HASHES and INSTALL_MOD_STRIP are mutually exclusive)
+ifneq ($(INSTALL_MOD_STRIP),$(CONFIG_MODULE_INSTALL_STRIP))
+$(error Inconsistent values for INSTALL_MOD_STRIP between build and installation)
 endif
 endif
 endif
diff --git a/scripts/Makefile.vmlinux b/scripts/Makefile.vmlinux
index a0332c06bde1..a2d170241a2f 100644
--- a/scripts/Makefile.vmlinux
+++ b/scripts/Makefile.vmlinux
@@ -86,7 +86,7 @@ modules.order: vmlinux.unstripped FORCE
 	$(Q)$(MAKE) -f $(srctree)/Makefile modules
 
 quiet_cmd_modules_merkle_tree = MERKLE  $@
-      cmd_modules_merkle_tree = $< $@ .ko
+      cmd_modules_merkle_tree = $< $@ $(if $(CONFIG_MODULE_INSTALL_STRIP),.ko.stripped,.ko)
 
 targets += .tmp_module_hashes.c
 .tmp_module_hashes.c: $(objtree)/scripts/modules-merkle-tree modules.order FORCE

-- 
2.54.0