[PATCH 02/14] target/s390x: Fix CLM with M3=0

[Ilya Leoshkevich <iii@linux.ibm.com>]

When the mask is zero, access exceptions should still be recognized for
1 byte at the second-operand address. CC should be set to 0.

Cc: qemu-stable@nongnu.org
Fixes: defb0e3157af ("s390x: Implement opcode helpers")
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
---
 target/s390x/tcg/mem_helper.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/target/s390x/tcg/mem_helper.c b/target/s390x/tcg/mem_helper.c
index f417fb1183c..d6dc8b32620 100644
--- a/target/s390x/tcg/mem_helper.c
+++ b/target/s390x/tcg/mem_helper.c
@@ -667,6 +667,11 @@ uint32_t HELPER(clm)(CPUS390XState *env, uint32_t r1, uint32_t mask,
     HELPER_LOG("%s: r1 0x%x mask 0x%x addr 0x%" PRIx64 "\n", __func__, r1,
                mask, addr);
 
+    if (!mask) {
+        /* Recognize access exceptions for the first byte */
+        cpu_ldub_data_ra(env, addr, ra);
+    }
+
     while (mask) {
         if (mask & 8) {
             uint8_t d = cpu_ldub_data_ra(env, addr, ra);
-- 
2.41.0