target/arm: Fix int128_make128 lo, hi order in paired_cmpxchg64_be

The lo,hi order is different from the comments. And in commit
1ec182c33379 ("target/arm: Convert to HAVE_CMPXCHG128"), it changes
the original code logic. So just restore the old code logic before this
commit:
do_paired_cmpxchg64_be():
    cmpv = int128_make128(env->exclusive_high, env->exclusive_val);
    newv = int128_make128(new_hi, new_lo);

This fixes a bug that would only be visible for big-endian
AArch64 guest code.

Fixes: 1ec182c33379 ("target/arm: Convert to HAVE_CMPXCHG128")
Signed-off-by: Catherine Ho <catherine.hecx@gmail.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 1548985244-24523-1-git-send-email-catherine.hecx@gmail.com
[PMM: added note that bug only affects BE guests]
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

1 files changed, 2 insertions, 2 deletions

diff --git a/target/arm/helper-a64.c b/target/arm/helper-a64.c
index 101fa6d3ea..70850e564d 100644
--- a/target/arm/helper-a64.c
+++ b/target/arm/helper-a64.c
@@ -583,8 +583,8 @@ uint64_t HELPER(paired_cmpxchg64_be)(CPUARMState *env, uint64_t addr,
      * High and low need to be switched here because this is not actually a
      * 128bit store but two doublewords stored consecutively
      */
-    Int128 cmpv = int128_make128(env->exclusive_val, env->exclusive_high);
-    Int128 newv = int128_make128(new_lo, new_hi);
+    Int128 cmpv = int128_make128(env->exclusive_high, env->exclusive_val);
+    Int128 newv = int128_make128(new_hi, new_lo);
     Int128 oldv;
     uintptr_t ra = GETPC();
     uint64_t o0, o1;