arm64: ensure the kernel is compiled for LP64

The kernel needs to be compiled as a LP64 binary for ARM64, even when
using a compiler that defaults to code-generation for the ILP32 ABI.
Consequently, we need to explicitly pass '-mabi=lp64' (supported on
gcc-4.9 and newer).

Signed-off-by: Andrew Pinski <[e-mail]>
Signed-off-by: Philipp Tomsich <[e-mail]>
Signed-off-by: Christoph Muellner <[e-mail]>
Signed-off-by: Yury Norov <[e-mail]>
Reviewed-by: David Daney <[e-mail]>
Signed-off-by: Catalin Marinas <[e-mail]>

arch/arm64/Makefile

···
 KBUILD_CFLAGS	+= $(call cc-option, -mpc-relative-literal-loads)
 KBUILD_AFLAGS	+= $(lseinstr) $(brokengasinst)
 
+KBUILD_CFLAGS	+= $(call cc-option,-mabi=lp64)
+KBUILD_AFLAGS	+= $(call cc-option,-mabi=lp64)
+
 ifeq ($(CONFIG_CPU_BIG_ENDIAN), y)
 KBUILD_CPPFLAGS	+= -mbig-endian
 CHECKFLAGS	+= -D__AARCH64EB__
 AS		+= -EB
 LD		+= -EB
+LDFLAGS		+= -maarch64linuxb
 UTS_MACHINE	:= aarch64_be
 else
 KBUILD_CPPFLAGS	+= -mlittle-endian
 CHECKFLAGS	+= -D__AARCH64EL__
 AS		+= -EL
 LD		+= -EL
+LDFLAGS		+= -maarch64linux
 UTS_MACHINE	:= aarch64
 endif