target/arm: Use helper_retaddr in stxp helpers

We use raw memory primitives along the !parallel_cpus paths in order to
simplify the endianness handling.  Because of that, we did not benefit
from the generic changes to cpu_ldst_user_only_template.h.

The simplest fix is to manipulate helper_retaddr here.
Reviewed-by: NAlex Bennée <alex.bennee@linaro.org>
Signed-off-by: NRichard Henderson <richard.henderson@linaro.org>

target/arm/helper-a64.c

@@ -456,6 +456,8 @@ static uint64_t do_paired_cmpxchg64_le(CPUARMState *env, uint64_t addr,
 #ifdef CONFIG_USER_ONLY
         /* ??? Enforce alignment.  */
         uint64_t *haddr = g2h(addr);
+
+        helper_retaddr = ra;
         o0 = ldq_le_p(haddr + 0);
         o1 = ldq_le_p(haddr + 1);
         oldv = int128_make128(o0, o1);
@@ -465,6 +467,7 @@ static uint64_t do_paired_cmpxchg64_le(CPUARMState *env, uint64_t addr,
             stq_le_p(haddr + 0, int128_getlo(newv));
             stq_le_p(haddr + 1, int128_gethi(newv));
         }
+        helper_retaddr = 0;
 #else
         int mem_idx = cpu_mmu_index(env, false);
         TCGMemOpIdx oi0 = make_memop_idx(MO_LEQ | MO_ALIGN_16, mem_idx);
@@ -523,6 +526,8 @@ static uint64_t do_paired_cmpxchg64_be(CPUARMState *env, uint64_t addr,
 #ifdef CONFIG_USER_ONLY
         /* ??? Enforce alignment.  */
         uint64_t *haddr = g2h(addr);
+
+        helper_retaddr = ra;
         o1 = ldq_be_p(haddr + 0);
         o0 = ldq_be_p(haddr + 1);
         oldv = int128_make128(o0, o1);
@@ -532,6 +537,7 @@ static uint64_t do_paired_cmpxchg64_be(CPUARMState *env, uint64_t addr,
             stq_be_p(haddr + 0, int128_gethi(newv));
             stq_be_p(haddr + 1, int128_getlo(newv));
         }
+        helper_retaddr = 0;
 #else
         int mem_idx = cpu_mmu_index(env, false);
         TCGMemOpIdx oi0 = make_memop_idx(MO_BEQ | MO_ALIGN_16, mem_idx);