powerpc: Clear ELF personality flag if ELFv2 is not requested.

powerpc: Clear ELF personality flag if ELFv2 is not requested.

The POWER kernel uses a personality flag to determine whether it should
be setting up function descriptors or not (per the updated ABI).  This
flag wasn't being cleared on a new process but instead was being
inherited.  The visible effect was that an ELFv2 binary could not execve
to an ELFv1 binary.
Signed-off-by: NJeff Bailey <jeffbailey@google.com>

 arch/powerpc/include/asm/elf.h | 2 ++
 1 file changed, 2 insertions(+)
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

arch/powerpc/include/asm/elf.h

@@ -90,6 +90,8 @@ typedef elf_vrregset_t elf_fpxregset_t;
 do {								\
 	if (((ex).e_flags & 0x3) == 2)				\
 		set_thread_flag(TIF_ELF2ABI);			\
+	else							\
+		clear_thread_flag(TIF_ELF2ABI);			\
 	if ((ex).e_ident[EI_CLASS] == ELFCLASS32)		\
 		set_thread_flag(TIF_32BIT);			\
 	else							\