[PATCH] arm64: vdso: Fix ABI regression in compat vdso

[Vincenzo Frascino]

Prior to the introduction of Unified vDSO support and compat layer for
vDSO on arm64, AT_SYSINFO_EHDR was not defined for compat tasks.
In the current implementation, AT_SYSINFO_EHDR is defined even if the
compat vdso layer is not built and this causes a regression in the
expected behavior of the ABI.

Restore the ABI behavior making sure that AT_SYSINFO_EHDR for compat
tasks is defined only when CONFIG_GENERIC_COMPAT_VDSO and
CONFIG_COMPAT_VDSO are enabled.

Reported-by: John Stultz <john.stultz@xxxxxxxxxx>
Signed-off-by: Vincenzo Frascino <vincenzo.frascino@xxxxxxx>
---
 arch/arm64/include/asm/elf.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm64/include/asm/elf.h b/arch/arm64/include/asm/elf.h
index 3c7037c6ba9b..b7992bb9d414 100644
--- a/arch/arm64/include/asm/elf.h
+++ b/arch/arm64/include/asm/elf.h
@@ -202,7 +202,7 @@ typedef compat_elf_greg_t		compat_elf_gregset_t[COMPAT_ELF_NGREG];
 ({									\
 	set_thread_flag(TIF_32BIT);					\
  })
-#ifdef CONFIG_GENERIC_COMPAT_VDSO
+#if defined(CONFIG_COMPAT_VDSO) && defined(CONFIG_GENERIC_COMPAT_VDSO)
 #define COMPAT_ARCH_DLINFO						\
 do {									\
 	/*								\
-- 
2.22.0