From 34f5d5923f3dff832fbc62a61a062643d78e4c03 Mon Sep 17 00:00:00 2001
From: Raoul Strackx <raoul.strackx@fortanix.com>
Date: Fri, 25 Oct 2019 15:44:07 +0200
Subject: [PATCH] cleaning up code

---
 src/libstd/sys/sgx/abi/entry.S | 13 ++++---------
 1 file changed, 4 insertions(+), 9 deletions(-)

diff --git a/src/libstd/sys/sgx/abi/entry.S b/src/libstd/sys/sgx/abi/entry.S
index 08aee89fe03de..f5d9c4338deb5 100644
--- a/src/libstd/sys/sgx/abi/entry.S
+++ b/src/libstd/sys/sgx/abi/entry.S
@@ -119,16 +119,11 @@ sgx_entry:
     mov %rbx,%gs:tcsls_tcs_addr
     stmxcsr %gs:tcsls_user_mxcsr
     fnstcw %gs:tcsls_user_fcw
-/*  reset user state */
-    cld /* x86-64 ABI requires DF to be unset at function entry/exit */
 
-/*  making sure AC flag is not set in rflags */
-/*  avoid using the 'clac' instruction to be compatible with older compilers */
-    pushfq
-    popq %rcx
-    and $0xFFFFFFFFFFFBFFFF, %rcx
-    push %rcx
-    popfq
+/*  reset user state */
+/*    - DF flag: x86-64 ABI requires DF to be unset at function entry/exit */
+/*    - AC flag: AEX on misaligned memory accesses leaks side channel info */
+    andq $~0x40400, (%rsp)
 
 /*  check for debug buffer pointer */
     testb  $0xff,DEBUG(%rip)