powerpc: Add TIF_ELF2ABI flag.

Little endian ppc64 is getting an exciting new ABI.  This is reflected
by the bottom two bits of e_flags in the ELF header:

	0 == legacy binaries (v1 ABI)
	1 == binaries using the old ABI (compiled with a new toolchain)
	2 == binaries using the new ABI.

We store this in a thread flag, because we need to set it in core
dumps and for signal delivery.  Our chief concern is that it doesn't
use function descriptors.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

2 files changed, 11 insertions, 0 deletions

diff --git a/arch/powerpc/include/asm/elf.h b/arch/powerpc/include/asm/elf.h
index cc0655a702a7..6d0e2369fe81 100644
--- a/arch/powerpc/include/asm/elf.h
+++ b/arch/powerpc/include/asm/elf.h
@@ -86,6 +86,8 @@ typedef elf_vrregset_t elf_fpxregset_t;
 #ifdef __powerpc64__
 # define SET_PERSONALITY(ex)                                    \
 do {                                                            \
+        if (((ex).e_flags & 0x3) == 2)                          \
+                set_thread_flag(TIF_ELF2ABI);                   \
         if ((ex).e_ident[EI_CLASS] == ELFCLASS32)               \
                 set_thread_flag(TIF_32BIT);                     \
         else                                                    \
diff --git a/arch/powerpc/include/asm/thread_info.h b/arch/powerpc/include/asm/thread_info.h
index ba7b1973866e..05a3030b4582 100644
--- a/arch/powerpc/include/asm/thread_info.h
+++ b/arch/powerpc/include/asm/thread_info.h
@@ -107,6 +107,9 @@ static inline struct thread_info *current_thread_info(void)
 #define TIF_EMULATE_STACK_STORE 16      /* Is an instruction emulation
                                                 for stack store? */
 #define TIF_MEMDIE              17      /* is terminating due to OOM killer */
+#if defined(CONFIG_PPC64)
+#define TIF_ELF2ABI             18      /* function descriptors must die! */
+#endif
 
 /* as above, but as bit values */
 #define _TIF_SYSCALL_TRACE      (1<<TIF_SYSCALL_TRACE)
@@ -185,6 +188,12 @@ static inline bool test_thread_local_flags(unsigned int flags)
 #define is_32bit_task() (1)
 #endif
 
+#if defined(CONFIG_PPC64)
+#define is_elf2_task() (test_thread_flag(TIF_ELF2ABI))
+#else
+#define is_elf2_task() (0)
+#endif
+
 #endif  /* !__ASSEMBLY__ */
 
 #endif /* __KERNEL__ */