s390x: remove duplicate definitions of DIAG 501

When restoring the previously saved instruction in
kvm_arch_remove_sw_breakpoint(), we only restored one byte. Let's use
the sizeof() operator to make sure we restore the entire instruction.

While we are at it, let's remove the duplicate definitions of DIAG 501
and replace its size (used when reading/writing the instruction) with
a sizeof() operator to make the code self explaining and less error-prone.
Signed-off-by: NDavid Hildenbrand <dahi@linux.vnet.ibm.com>
Reviewed-by: NCornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: NJens Freimann <jfrei@linux.vnet.ibm.com>
Signed-off-by: NCornelia Huck <cornelia.huck@de.ibm.com>

target-s390x/kvm.c

@@ -320,12 +320,16 @@ static void *legacy_s390_alloc(size_t size)
     return mem == MAP_FAILED ? NULL : mem;
 }
 
+/* DIAG 501 is used for sw breakpoints */
+static const uint8_t diag_501[] = {0x83, 0x24, 0x05, 0x01};
+
 int kvm_arch_insert_sw_breakpoint(CPUState *cs, struct kvm_sw_breakpoint *bp)
 {
-    static const uint8_t diag_501[] = {0x83, 0x24, 0x05, 0x01};
 
-    if (cpu_memory_rw_debug(cs, bp->pc, (uint8_t *)&bp->saved_insn, 4, 0) ||
-        cpu_memory_rw_debug(cs, bp->pc, (uint8_t *)diag_501, 4, 1)) {
+    if (cpu_memory_rw_debug(cs, bp->pc, (uint8_t *)&bp->saved_insn,
+                            sizeof(diag_501), 0) ||
+        cpu_memory_rw_debug(cs, bp->pc, (uint8_t *)diag_501,
+                            sizeof(diag_501), 1)) {
         return -EINVAL;
     }
     return 0;
@@ -333,14 +337,14 @@ int kvm_arch_insert_sw_breakpoint(CPUState *cs, struct kvm_sw_breakpoint *bp)
 
 int kvm_arch_remove_sw_breakpoint(CPUState *cs, struct kvm_sw_breakpoint *bp)
 {
-    uint8_t t[4];
-    static const uint8_t diag_501[] = {0x83, 0x24, 0x05, 0x01};
+    uint8_t t[sizeof(diag_501)];
 
-    if (cpu_memory_rw_debug(cs, bp->pc, t, 4, 0)) {
+    if (cpu_memory_rw_debug(cs, bp->pc, t, sizeof(diag_501), 0)) {
         return -EINVAL;
-    } else if (memcmp(t, diag_501, 4)) {
+    } else if (memcmp(t, diag_501, sizeof(diag_501))) {
         return -EINVAL;
-    } else if (cpu_memory_rw_debug(cs, bp->pc, (uint8_t *)&bp->saved_insn, 1, 1)) {
+    } else if (cpu_memory_rw_debug(cs, bp->pc, (uint8_t *)&bp->saved_insn,
+                                   sizeof(diag_501), 1)) {
         return -EINVAL;
     }