Re: [PATCH] integrity: avoid using __weak functions

[Nathan Chancellor <nathan@kernel.org>]

On Fri, Mar 06, 2026 at 04:03:24PM +0100, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@arndb.de>
> 
> The security/integrity/secure_boot.c file containing only a __weak function
> leads to a build failure with clang:
> 
> Cannot find symbol for section 2: .text.
> security/integrity/secure_boot.o: failed
> 
> Moving the function into another file that has at least one non-__weak
> symbol would solve this, but this is always fragile.
> 
> Avoid __weak definitions entirely and instead move the stub helper into
> an asm-generic header that gets used by default on architectures that
> do not provide their own version. This is consistent with how a lot
> of other architecture specific functionality works, and is more reliable.
> 
> Fixes: a0f87ede3bf4 ("integrity: Make arch_ima_get_secureboot integrity-wide")
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
> This is a larger change than I had hoped for.
> 
> If you prefer a different way to address the build failure, please
> treat this as a Reported-by when you apply your own fix
> ---
>  arch/powerpc/include/asm/secure_boot.h        |  6 +++
>  arch/powerpc/kernel/secure_boot.c             |  1 -
>  arch/s390/include/asm/secure_boot.h           |  9 +++++
>  include/asm-generic/Kbuild                    |  1 +
>  include/asm-generic/secure_boot.h             | 37 +++++++++++++++++++
>  include/linux/secure_boot.h                   |  8 +---
>  security/integrity/Makefile                   |  2 +-
>  .../integrity/platform_certs/load_powerpc.c   |  2 +-
>  security/integrity/secure_boot.c              | 16 --------
>  9 files changed, 56 insertions(+), 26 deletions(-)
>  create mode 100644 arch/s390/include/asm/secure_boot.h
>  create mode 100644 include/asm-generic/secure_boot.h
>  delete mode 100644 security/integrity/secure_boot.c

Thanks, I noticed this as well. The version I came up with and have been
locally testing is the following, which is a little bit more compact.

 arch/Kconfig                     |  3 +++
 arch/powerpc/Kconfig             |  1 +
 arch/s390/Kconfig                |  1 +
 arch/s390/kernel/ipl.c           | 10 +++++-----
 include/linux/secure_boot.h      |  4 ++++
 security/integrity/Makefile      |  2 +-
 security/integrity/secure_boot.c | 16 ----------------
 7 files changed, 15 insertions(+), 22 deletions(-)

diff --git a/arch/Kconfig b/arch/Kconfig
index 102ddbd4298e..a6d1c8cc1d64 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -1841,4 +1841,7 @@ config ARCH_WANTS_PRE_LINK_VMLINUX
 config ARCH_HAS_CPU_ATTACK_VECTORS
 	bool
 
+config HAVE_ARCH_GET_SECUREBOOT
+	def_bool EFI
+
 endmenu
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index c28776660246..e76d6cf0c403 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -1062,6 +1062,7 @@ config PPC_SECURE_BOOT
 	depends on IMA_ARCH_POLICY
 	imply IMA_SECURE_AND_OR_TRUSTED_BOOT
 	select PSERIES_PLPKS if PPC_PSERIES
+	select HAVE_ARCH_GET_SECUREBOOT
 	help
 	  Systems with firmware secure boot enabled need to define security
 	  policies to extend secure boot to the OS. This config allows a user
diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index 24695ea29d5b..76f191dd208b 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -181,6 +181,7 @@ config S390
 	select GENERIC_IOREMAP if PCI
 	select HAVE_ALIGNED_STRUCT_PAGE
 	select HAVE_ARCH_AUDITSYSCALL
+	select HAVE_ARCH_GET_SECUREBOOT
 	select HAVE_ARCH_JUMP_LABEL
 	select HAVE_ARCH_JUMP_LABEL_RELATIVE
 	select HAVE_ARCH_KASAN
diff --git a/arch/s390/kernel/ipl.c b/arch/s390/kernel/ipl.c
index 2d01a1713938..3c346b02ceb9 100644
--- a/arch/s390/kernel/ipl.c
+++ b/arch/s390/kernel/ipl.c
@@ -2388,6 +2388,11 @@ void __no_stack_protector s390_reset_system(void)
 	diag_amode31_ops.diag308_reset();
 }
 
+bool arch_get_secureboot(void)
+{
+	return ipl_secure_flag;
+}
+
 #ifdef CONFIG_KEXEC_FILE
 
 int ipl_report_add_component(struct ipl_report *report, struct kexec_buf *kbuf,
@@ -2505,11 +2510,6 @@ void *ipl_report_finish(struct ipl_report *report)
 	return buf;
 }
 
-bool arch_get_secureboot(void)
-{
-	return ipl_secure_flag;
-}
-
 int ipl_report_free(struct ipl_report *report)
 {
 	struct ipl_report_component *comp, *ncomp;
diff --git a/include/linux/secure_boot.h b/include/linux/secure_boot.h
index 3ded3f03655c..d17e92351567 100644
--- a/include/linux/secure_boot.h
+++ b/include/linux/secure_boot.h
@@ -10,10 +10,14 @@
 
 #include <linux/types.h>
 
+#ifdef CONFIG_HAVE_ARCH_GET_SECUREBOOT
 /*
  * Returns true if the platform secure boot is enabled.
  * Returns false if disabled or not supported.
  */
 bool arch_get_secureboot(void);
+#else
+static inline bool arch_get_secureboot(void) { return false; }
+#endif
 
 #endif /* _LINUX_SECURE_BOOT_H */
diff --git a/security/integrity/Makefile b/security/integrity/Makefile
index 548665e2b702..45dfdedbdad4 100644
--- a/security/integrity/Makefile
+++ b/security/integrity/Makefile
@@ -5,7 +5,7 @@
 
 obj-$(CONFIG_INTEGRITY) += integrity.o
 
-integrity-y := iint.o secure_boot.o
+integrity-y := iint.o
 integrity-$(CONFIG_INTEGRITY_AUDIT) += integrity_audit.o
 integrity-$(CONFIG_INTEGRITY_SIGNATURE) += digsig.o
 integrity-$(CONFIG_INTEGRITY_ASYMMETRIC_KEYS) += digsig_asymmetric.o
diff --git a/security/integrity/secure_boot.c b/security/integrity/secure_boot.c
deleted file mode 100644
index fc2693c286f8..000000000000
--- a/security/integrity/secure_boot.c
+++ /dev/null
@@ -1,16 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0-only
-/*
- * Copyright (C) 2026 Red Hat, Inc. All Rights Reserved.
- *
- * Author: Coiby Xu <coxu@redhat.com>
- */
-#include <linux/secure_boot.h>
-
-/*
- * Default weak implementation.
- * Architectures that support secure boot must override this.
- */
-__weak bool arch_get_secureboot(void)
-{
-	return false;
-}