On 24 May 2014, at 09:02 , Andrew Pinski [off-list ref] wrote:

#ifdef CONFIG_COMPAT
-#define COMPAT_ELF_HWCAP	(compat_elf_hwcap)
-#define COMPAT_ELF_HWCAP2	(compat_elf_hwcap2)
extern unsigned int compat_elf_hwcap, compat_elf_hwcap2;
+#define COMPAT_ELF_HWCAP	\
+	(is_a32_compat_task()	\
+	  ? compat_elf_hwcap	\
+	  : elf_hwcap)
+
+#define COMPAT_ELF_HWCAP2	\
+	(is_a32_compat_task()	\
+	  ? compat_elf_hwcap2	\
+	  : 0)
+
#endif

You missed the COMPAT_ELF_PLATFORM (in arm64/include/asm/elf.h), which is used to setup AT_PLATFORM in the auxilary vectors. I?d suggest to use a similar naming convention to what will be used in gdb (i.e. appending a ?:ilp32? to the base architecture.

The proposed change would thus be:
---
 arch/arm64/include/asm/elf.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/include/asm/elf.h b/arch/arm64/include/asm/elf.h
index 3f979b5..6d38edc 100644
--- a/arch/arm64/include/asm/elf.h
+++ b/arch/arm64/include/asm/elf.h

@@ -168,9 +168,9 @@ extern unsigned long arch_randomize_brk(struct mm_struct *mm);
 #ifdef CONFIG_COMPAT
 
 #ifdef __AARCH64EB__
-#define COMPAT_ELF_PLATFORM            ("v8b")
+#define COMPAT_ELF_PLATFORM            (is_ilp32_compat_task() ? "aarch64_be:ilp32" : "v8b")
 #else
-#define COMPAT_ELF_PLATFORM            ("v8l")
+#define COMPAT_ELF_PLATFORM            (is_ilp32_compat_task() ? "aarch64:ilp32" : "v8l")
 #endif
 
 #define COMPAT_ELF_ET_DYN_BASE         (randomize_et_dyn(2 * TASK_SIZE_32 / 3))

-- 
1.9.0


Best,
Philipp.