ANDROID: arm64: module: add RELA metadata for FIPS140 use

The fips140.ko module relies on ELF metadata that is normally discarded
by the module loader. In order to reduce the impact of the associated
changes on non-FIPS140 kernels, the module loader will be modified to
simply copy this metadata if it encounters a module whose name is
'fips140'. For this to work, we need a couple of fields in struct
mod_arch_specific so that this module can find this data at module init
time.

Adding these fields will change the type signature of struct module, and
hence affect the stable ABI. The FIPS140 module build depends on LTO,
and so its Kconfig symbol can only be enabled if LTO is enabled as well.
This implies that adding these mod_arch_specific fields conditionally,
based on CONFIG_CRYPTO_FIPS140_INTEGRITY_CHECK, would result in an ABI
fork between LTO and !LTO builds, which is obviously undesirable.

So let's just add these fields unconditionally. This will take 24 bytes
of kernel memory per module, but given that the size of struct module
(which is the only place where struct mod_arch_specific is allocated) is
rounded up to cacheline size (128 bytes on arm64), and this change does
not push it over the edge, the net result is that no additional memory
is used (struct module is currently 1 KiB)

Bug: 153614920
Change-Id: Ia617762f37c0bf7324e899b72fd317e382e39c03
Signed-off-by: Ard Biesheuvel <ardb@google.com>

arch/arm64/include/asm/module.h

@@ -20,6 +20,12 @@ struct mod_arch_specific {
 
 	/* for CONFIG_DYNAMIC_FTRACE */
 	struct plt_entry	*ftrace_trampolines;
+
+	/* for FIPS 140 certified kernel module */
+	const Elf64_Rela	*text_relocations;
+	const Elf64_Rela	*rodata_relocations;
+	int			num_text_relocations;
+	int			num_rodata_relocations;
 };
 #endif