ANDROID: add __kexporttab section to vmlinux

This section will contain all symbols which are forbidden from being
exported by unsigned modules.

Bug: 519119852
Change-Id: Ia5ba5785fd90488fc1623b696d4010d7b7ec449c
Signed-off-by: Siddharth Nayyar <sidnayyar@google.com>

include/asm-generic/vmlinux.lds.h

@@ -529,8 +529,15 @@
 		__stop___kflagstab = .;					\
 	}								\
 									\
+	/* Kernel protected exports table */				\
+	__kexporttab      : AT(ADDR(__kexporttab) - LOAD_OFFSET) {	\
+		__start___kexporttab = .;				\
+		KEEP(*(SORT(___kexporttab+*)))				\
+		__stop___kexporttab = .;				\
+	}								\
+									\
 	/* Kernel symbol table: strings */				\
-        __ksymtab_strings : AT(ADDR(__ksymtab_strings) - LOAD_OFFSET) {	\
+	__ksymtab_strings : AT(ADDR(__ksymtab_strings) - LOAD_OFFSET) {	\
 		*(__ksymtab_strings)					\
 	}								\
 									\