arm64: Add COMPAT_HWCAP_LPAE

Commit a469abd0f868 (ARM: elf: add new hwcap for identifying atomic
ldrd/strd instructions) introduces HWCAP_ELF for 32-bit ARM
applications. As LPAE is always present on arm64, report the
corresponding compat HWCAP to user space.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: <stable@vger.kernel.org> # 3.11+
Signed-off-by: Will Deacon <will.deacon@arm.com>

arch/arm64/include/asm/hwcap.h

@@ -30,6 +30,7 @@
 #define COMPAT_HWCAP_IDIVA	(1 << 17)
 #define COMPAT_HWCAP_IDIVT	(1 << 18)
 #define COMPAT_HWCAP_IDIV	(COMPAT_HWCAP_IDIVA|COMPAT_HWCAP_IDIVT)
+#define COMPAT_HWCAP_LPAE	(1 << 20)
 #define COMPAT_HWCAP_EVTSTRM	(1 << 21)
 
 #define COMPAT_HWCAP2_AES	(1 << 0)

arch/arm64/kernel/setup.c

@@ -73,7 +73,8 @@ EXPORT_SYMBOL_GPL(elf_hwcap);
 				 COMPAT_HWCAP_FAST_MULT|COMPAT_HWCAP_EDSP|\
 				 COMPAT_HWCAP_TLS|COMPAT_HWCAP_VFP|\
 				 COMPAT_HWCAP_VFPv3|COMPAT_HWCAP_VFPv4|\
-				 COMPAT_HWCAP_NEON|COMPAT_HWCAP_IDIV)
+				 COMPAT_HWCAP_NEON|COMPAT_HWCAP_IDIV|\
+				 COMPAT_HWCAP_LPAE)
 unsigned int compat_elf_hwcap __read_mostly = COMPAT_ELF_HWCAP_DEFAULT;
 unsigned int compat_elf_hwcap2 __read_mostly;
 #endif