trace: only permit standard C types and fixed size integer types

Some trace backends will compile code based on the declared trace
events. It should not be assumed that the backends can resolve any QEMU
specific typedefs. So trace events should restrict their argument
types to the standard C types and fixed size integer types. Any complex
pointer types can be declared as "void *" for purposes of trace events,
since nothing will be dereferencing these pointer arguments.

Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Message-id: 20180308155524.5082-3-berrange@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

scripts/tracetool/__init__.py

@@ -41,6 +41,51 @@ def out(*lines, **kwargs):
     lines = [ l % kwargs for l in lines ]
     sys.stdout.writelines("\n".join(lines) + "\n")
 
+# We only want to allow standard C types or fixed sized
+# integer types. We don't want QEMU specific types
+# as we can't assume trace backends can resolve all the
+# typedefs
+ALLOWED_TYPES = [
+    "int",
+    "long",
+    "short",
+    "char",
+    "bool",
+    "unsigned",
+    "signed",
+    "float",
+    "double",
+    "int8_t",
+    "uint8_t",
+    "int16_t",
+    "uint16_t",
+    "int32_t",
+    "uint32_t",
+    "int64_t",
+    "uint64_t",
+    "void",
+    "size_t",
+    "ssize_t",
+    "uintptr_t",
+    "ptrdiff_t",
+    # Magic substitution is done by tracetool
+    "TCGv",
+]
+
+def validate_type(name):
+    bits = name.split(" ")
+    for bit in bits:
+        bit = re.sub("\*", "", bit)
+        if bit == "":
+            continue
+        if bit == "const":
+            continue
+        if bit not in ALLOWED_TYPES:
+            raise ValueError("Argument type '%s' is not in whitelist. "
+                             "Only standard C types and fixed size integer "
+                             "types should be used. struct, union, and "
+                             "other complex pointer types should be "
+                             "declared as 'void *'" % name)
 
 class Arguments:
     """Event arguments description."""
@@ -87,6 +132,7 @@ class Arguments:
             else:
                 arg_type, identifier = arg.rsplit(None, 1)
 
+            validate_type(arg_type)
             res.append((arg_type, identifier))
         return Arguments(res)