powerpc/64s: Remove support for ELFv1 little endian userspace

ELFv2 was introduced together with little-endian. ELFv1 with LE has
never been a thing. The GNU toolchain can create such a beast, but
anyone doing that is a maniac who needs to be stopped so I consider
this patch a feature.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20230606093832.199712-5-npiggin@gmail.com

arch/powerpc/include/asm/elf.h

@@ -12,8 +12,14 @@
 
 /*
  * This is used to ensure we don't load something for the wrong architecture.
+ * 64le only supports ELFv2 64-bit binaries (64be supports v1 and v2).
  */
+#if defined(CONFIG_PPC64) && defined(CONFIG_CPU_LITTLE_ENDIAN)
+#define elf_check_arch(x) (((x)->e_machine == ELF_ARCH) && \
+			   (((x)->e_flags & 0x3) == 0x2))
+#else
 #define elf_check_arch(x) ((x)->e_machine == ELF_ARCH)
+#endif
 #define compat_elf_check_arch(x)	((x)->e_machine == EM_PPC)
 
 #define CORE_DUMP_USE_REGSET

arch/powerpc/include/asm/thread_info.h

@@ -183,9 +183,13 @@ static inline bool test_thread_local_flags(unsigned int flags)
 #define clear_tsk_compat_task(tsk) do { } while (0)
 #endif
 
-#if defined(CONFIG_PPC64)
+#ifdef CONFIG_PPC64
+#ifdef CONFIG_CPU_BIG_ENDIAN
 #define is_elf2_task() (test_thread_flag(TIF_ELF2ABI))
 #else
+#define is_elf2_task() (1)
+#endif
+#else
 #define is_elf2_task() (0)
 #endif