disas: Let disas::read_memory() handler return EIO on error

Both cpu_memory_rw_debug() and address_space_read() return
an error on failed transaction. Check the returned value,
and return EIO in case of error.

Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

disas.c

@@ -39,9 +39,11 @@ target_read_memory (bfd_vma memaddr,
                     struct disassemble_info *info)
 {
     CPUDebug *s = container_of(info, CPUDebug, info);
+    int r;
 
-    cpu_memory_rw_debug(s->cpu, memaddr, myaddr, length, 0);
-    return 0;
+    r = cpu_memory_rw_debug(s->cpu, memaddr, myaddr, length, 0);
+
+    return r ? EIO : 0;
 }
 
 /* Print an error message.  We can assume that this is in response to
@@ -718,10 +720,11 @@ physical_read_memory(bfd_vma memaddr, bfd_byte *myaddr, int length,
                      struct disassemble_info *info)
 {
     CPUDebug *s = container_of(info, CPUDebug, info);
+    MemTxResult res;
 
-    address_space_read(s->cpu->as, memaddr, MEMTXATTRS_UNSPECIFIED,
-                       myaddr, length);
-    return 0;
+    res = address_space_read(s->cpu->as, memaddr, MEMTXATTRS_UNSPECIFIED,
+                             myaddr, length);
+    return res == MEMTX_OK ? 0 : EIO;
 }
 
 /* Disassembler for the monitor.  */