From afb67fc0023d4e8b671e503219107ac765955047 Mon Sep 17 00:00:00 2001
From: Richard Henderson <rth@twiddle.net>
Date: Thu, 8 Feb 2018 08:28:43 -0500
Subject: [PATCH] target/arm: Fix aa64 ldp register writeback

Backports commit 3e4d91b94ce400326fae0850578d9e9f30a71adb from qemu
---
 qemu/target-arm/translate-a64.c | 27 ++++++++++++++++-----------
 1 file changed, 16 insertions(+), 11 deletions(-)

diff --git a/qemu/target-arm/translate-a64.c b/qemu/target-arm/translate-a64.c
index 6103db58..a984b0e5 100644
--- a/qemu/target-arm/translate-a64.c
+++ b/qemu/target-arm/translate-a64.c
@@ -1986,29 +1986,34 @@ static void disas_ldst_pair(DisasContext *s, uint32_t insn)
         } else {
             do_fp_st(s, rt, tcg_addr, size);
         }
-    } else {
-        TCGv_i64 tcg_rt = cpu_reg(s, rt);
-        if (is_load) {
-            do_gpr_ld(s, tcg_rt, tcg_addr, size, is_signed, false);
-        } else {
-            do_gpr_st(s, tcg_rt, tcg_addr, size);
-        }
-    }
-    tcg_gen_addi_i64(tcg_ctx, tcg_addr, tcg_addr, 1ULL << size);
-    if (is_vector) {
+        tcg_gen_addi_i64(tcg_ctx, tcg_addr, tcg_addr, 1 << size);
         if (is_load) {
             do_fp_ld(s, rt2, tcg_addr, size);
         } else {
             do_fp_st(s, rt2, tcg_addr, size);
         }
     } else {
+        TCGv_i64 tcg_rt = cpu_reg(s, rt);
         TCGv_i64 tcg_rt2 = cpu_reg(s, rt2);
+
         if (is_load) {
+            TCGv_i64 tmp = tcg_temp_new_i64(tcg_ctx);
+
+            /* Do not modify tcg_rt before recognizing any exception
+             * from the second load.
+             */
+            do_gpr_ld(s, tmp, tcg_addr, size, is_signed, false);
+            tcg_gen_addi_i64(tcg_ctx, tcg_addr, tcg_addr, 1 << size);
             do_gpr_ld(s, tcg_rt2, tcg_addr, size, is_signed, false);
+
+            tcg_gen_mov_i64(tcg_ctx, tcg_rt, tmp);
+            tcg_temp_free_i64(tcg_ctx, tmp);
         } else {
+            do_gpr_st(s, tcg_rt, tcg_addr, size);
+            tcg_gen_addi_i64(tcg_ctx, tcg_addr, tcg_addr, 1 << size);
             do_gpr_st(s, tcg_rt2, tcg_addr, size);
         }
-    }
+}
 
     if (wback) {
         if (postindex) {