We can process a maximum of 256 bytes, crossing two pages.

Signed-off-by: David Hildenbrand <david@redhat.com>
---
 target/s390x/mem_helper.c | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/target/s390x/mem_helper.c b/target/s390x/mem_helper.c
index ba8a657e18..5e38b2c4d8 100644
--- a/target/s390x/mem_helper.c
+++ b/target/s390x/mem_helper.c
@@ -493,13 +493,21 @@ void HELPER(mvcin)(CPUS390XState *env, uint32_t l, uint64_t dest, uint64_t src)
 /* move numerics  */
 void HELPER(mvn)(CPUS390XState *env, uint32_t l, uint64_t dest, uint64_t src)
 {
+    S390Access srca1, srca2, desta;
     uintptr_t ra = GETPC();
     int i;
 
-    for (i = 0; i <= l; i++) {
-        uint8_t v = cpu_ldub_data_ra(env, dest + i, ra) & 0xf0;
-        v |= cpu_ldub_data_ra(env, src + i, ra) & 0x0f;
-        cpu_stb_data_ra(env, dest + i, v, ra);
+    /* MVN always copies one more byte than specified - maximum is 256 */
+    l++;
+
+    srca1 = access_prepare(env, src, l, MMU_DATA_LOAD, ra);
+    srca2 = access_prepare(env, dest, l, MMU_DATA_LOAD, ra);
+    desta = access_prepare(env, dest, l, MMU_DATA_STORE, ra);
+    for (i = 0; i < l; i++) {
+        const uint8_t x = (access_get_byte(env, &srca1, i, ra) & 0x0f) |
+                          (access_get_byte(env, &srca2, i, ra) & 0xf0);
+
+        access_set_byte(env, &desta, i, x, ra);
     }
 }
 
-- 
2.21.0

On 9/6/19 3:57 AM, David Hildenbrand wrote:
> We can process a maximum of 256 bytes, crossing two pages.
> 
> Signed-off-by: David Hildenbrand <david@redhat.com>
> ---
>  target/s390x/mem_helper.c | 16 ++++++++++++----
>  1 file changed, 12 insertions(+), 4 deletions(-)

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>

r~