security/integrity/secure_boot.c contains a single __weak function,
which breaks recordmcount when building with clang:

  $ make -skj"$(nproc)" ARCH=powerpc LLVM=1 ppc64_defconfig security/integrity/secure_boot.o
  Cannot find symbol for section 2: .text.
  security/integrity/secure_boot.o: failed

Introduce a Kconfig symbol, CONFIG_HAVE_ARCH_GET_SECUREBOOT, to indicate
that an architecture provides a definition of arch_get_secureboot().
Provide a static inline stub when this symbol is not defined to achieve
the same effect as the __weak function, allowing secure_boot.c to be
removed altogether. Move the s390 definition of arch_get_secureboot()
out of the CONFIG_KEXEC_FILE block to ensure it is always available, as
it does not actually depend on KEXEC_FILE.

Reported-by: Arnd Bergmann <arnd@arndb.de>
Fixes: 31a6a07eefeb ("integrity: Make arch_ima_get_secureboot integrity-wide")
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>

EVM and other LSMs need the ability to query the secure boot status of
the system, without directly calling the IMA arch_ima_get_secureboot
function. Refactor the secure boot status check into a general function
named arch_get_secureboot.

Reported-and-suggested-by: Mimi Zohar <zohar@linux.ibm.com>
Suggested-by: Roberto Sassu <roberto.sassu@huawei.com>
Signed-off-by: Coiby Xu <coxu@redhat.com>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>