arm64: ELF: add support for big-endian executables

This patch adds support for the aarch64_be ELF format to the AArch64 ELF
loader.
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

arch/arm64/include/asm/elf.h

@@ -90,11 +90,24 @@ typedef struct user_fpsimd_state elf_fpregset_t;
  * These are used to set parameters in the core dumps.
  */
 #define ELF_CLASS	ELFCLASS64
+#ifdef __AARCH64EB__
+#define ELF_DATA	ELFDATA2MSB
+#else
 #define ELF_DATA	ELFDATA2LSB
+#endif
 #define ELF_ARCH	EM_AARCH64
 
+/*
+ * This yields a string that ld.so will use to load implementation
+ * specific libraries for optimization.  This is more specific in
+ * intent than poking at uname or /proc/cpuinfo.
+ */
 #define ELF_PLATFORM_SIZE	16
+#ifdef __AARCH64EB__
+#define ELF_PLATFORM		("aarch64_be")
+#else
 #define ELF_PLATFORM		("aarch64")
+#endif
 
 /*
  * This is used to ensure we don't load something for the wrong architecture.