janitorial: create unified helper handler

Author: r41k0u

pythonbpf/bpf_helper_handler.py

@@ -6,6 +6,7 @@ def bpf_ktime_get_ns_emitter(call, module, builder, func):
     """
     Emit LLVM IR for bpf_ktime_get_ns helper function call.
     """
+    # func is an arg to just have a uniform signature with other emitters
     helper_id = ir.Constant(ir.IntType(64), 5)
     fn_type = ir.FunctionType(ir.IntType(64), [], var_arg=False)
     fn_ptr_type = ir.PointerType(fn_type)
@@ -14,15 +15,38 @@ def bpf_ktime_get_ns_emitter(call, module, builder, func):
     return result
 
 
-def bpf_map_lookup_elem_emitter(map_ptr, key_ptr, module, builder):
+def bpf_map_lookup_elem_emitter(call, map_ptr, module, builder, local_sym_tab=None):
     """
     Emit LLVM IR for bpf_map_lookup_elem helper function call.
     """
-    # Cast pointers to void*
+
+    if call.args and len(call.args) != 1:
+        raise ValueError("Map lookup expects exactly one argument, got "
+                         f"{len(call.args)}")
+    key_arg = call.args[0]
+    if isinstance(key_arg, ast.Name):
+        key_name = key_arg.id
+        if local_sym_tab and key_name in local_sym_tab:
+            key_ptr = local_sym_tab[key_name]
+        else:
+            raise ValueError(
+                f"Key variable {key_name} not found in local symbol table.")
+    elif isinstance(key_arg, ast.Constant) and isinstance(key_arg.value, int):
+        # handle constant integer keys
+        key_val = key_arg.value
+        key_type = ir.IntType(64)
+        key_ptr = builder.alloca(key_type)
+        key_ptr.align = key_type // 8
+        builder.store(ir.Constant(key_type, key_val), key_ptr)
+    else:
+        raise NotImplementedError(
+            "Only simple variable names are supported as keys in map lookup.")
+
+    if key_ptr is None:
+        raise ValueError("Key pointer is None.")
+
     map_void_ptr = builder.bitcast(map_ptr, ir.PointerType())
 
-    # Define function type for bpf_map_lookup_elem
-    # The function takes two void* arguments and returns void*
     fn_type = ir.FunctionType(
         ir.PointerType(),  # Return type: void*
         [ir.PointerType(), ir.PointerType()],  # Args: (void*, void*)
@@ -34,7 +58,6 @@ def bpf_map_lookup_elem_emitter(map_ptr, key_ptr, module, builder):
     fn_addr = ir.Constant(ir.IntType(64), 1)
     fn_ptr = builder.inttoptr(fn_addr, fn_ptr_type)
 
-    # Call the helper function
     result = builder.call(fn_ptr, [map_void_ptr, key_ptr], tail=False)
 
     return result
@@ -79,5 +102,31 @@ def bpf_printk_emitter(call, module, builder, func):
 }
 
 
-def handle_helper_call(call, module, builder, func):
-    return None
+def handle_helper_call(call, module, builder, func, local_sym_tab=None, map_sym_tab=None):
+    if isinstance(call.func, ast.Name):
+        func_name = call.func.id
+        if func_name in helper_func_list:
+            # it is not a map method call
+            helper_func_list[func_name](call, module, builder, func)
+        else:
+            raise NotImplementedError(
+                f"Function {func_name} is not implemented as a helper function.")
+    elif isinstance(call.func, ast.Attribute):
+        # likely a map method call
+        if isinstance(call.func.value, ast.Call) and isinstance(call.func.value.func, ast.Name):
+            map_name = call.func.value.func.id
+            method_name = call.func.attr
+            if map_sym_tab and map_name in map_sym_tab:
+                map_ptr = map_sym_tab[map_name]
+                if method_name in helper_func_list:
+                    helper_func_list[method_name](
+                        call, map_ptr, module, builder, local_sym_tab)
+                else:
+                    raise NotImplementedError(
+                        f"Map method {method_name} is not implemented as a helper function.")
+            else:
+                raise ValueError(
+                    f"Map variable {map_name} not found in symbol tables.")
+        else:
+            raise NotImplementedError(
+                "Attribute not supported for map method calls.")

pythonbpf/functions_pass.py

@@ -1,7 +1,7 @@
 from llvmlite import ir
 import ast
 
-from .bpf_helper_handler import bpf_printk_emitter, bpf_ktime_get_ns_emitter, bpf_map_lookup_elem_emitter
+from .bpf_helper_handler import helper_func_list, handle_helper_call
 from .type_deducer import ctypes_to_ir
 
 
@@ -60,55 +60,16 @@ def handle_assign(module, builder, stmt, map_sym_tab, local_sym_tab):
             else:
                 print(f"Unsupported assignment call type: {call_type}")
         elif isinstance(rval.func, ast.Attribute):
-            if isinstance(rval.func.attr, str) and rval.func.attr == "lookup":
-                # Get map name and check symtab
-                # maps are called as funcs
-                if isinstance(rval.func.value, ast.Call) and isinstance(rval.func.value.func, ast.Name):
-                    map_name = rval.func.value.func.id
-                    if map_name in map_sym_tab:
-                        map_global = map_sym_tab[map_name]
-                        print(f"Found map {map_name} in symtab for lookup")
-                        if len(rval.args) != 1:
-                            print("Unsupported lookup with != 1 arg")
-                            return
-                        key_arg = rval.args[0]
-                        print(f"Lookup key arg type: {type(key_arg)}")
-                        # TODO: implement a parse_arg ffs as this can be a fucking expr
-                        if isinstance(key_arg, ast.Constant) and isinstance(key_arg.value, int):
-                            key_val = key_arg.value
-                            key_type = ir.IntType(64)
-                            print(f"Key type: {key_type}")
-                            print(f"Key val: {key_val}")
-                            key_var = builder.alloca(key_type)
-                            key_var.align = key_type // 8
-                            builder.store(ir.Constant(
-                                key_type, key_val), key_var)
-                        elif isinstance(key_arg, ast.Name):
-                            # Check in local symtab first
-                            if key_arg.id in local_sym_tab:
-                                key_var = local_sym_tab[key_arg.id]
-                                key_type = key_var.type.pointee
-                            elif key_arg.id in map_sym_tab:
-                                key_var = map_sym_tab[key_arg.id]
-                                key_type = key_var.type.pointee
-                            else:
-                                print("Key variable "
-                                      f"{key_arg.id} not found in symtabs")
-                                return
-                            print(f"Found key variable {key_arg.id} in symtab")
-                            print(f"Key type: {key_type}")
-                        else:
-                            print("Unsupported lookup key arg")
-                            return
-
-                        # TODO: generate call to bpf_map_lookup_elem
-                        result_ptr = bpf_map_lookup_elem_emitter(
-                            map_global, key_var, module, builder)
-
-                    else:
-                        print(f"Map {map_name} not found in symbol table")
+            if isinstance(rval.func.value, ast.Call) and isinstance(rval.func.value.func, ast.Name):
+                map_name = rval.func.value.func.id
+                method_name = rval.func.attr
+                if map_name in map_sym_tab:
+                    map_ptr = map_sym_tab[map_name]
+                    if method_name in helper_func_list:
+                        handle_helper_call(
+                            rval, module, builder, None, local_sym_tab, map_sym_tab)
             else:
-                print("Unsupported assignment from method call")
+                print("Unsupported assignment call structure")
 
 
 def process_func_body(module, builder, func_node, func, ret_type, map_sym_tab):
@@ -121,10 +82,11 @@ def process_func_body(module, builder, func_node, func, ret_type, map_sym_tab):
     for stmt in func_node.body:
         if isinstance(stmt, ast.Expr) and isinstance(stmt.value, ast.Call):
             call = stmt.value
-            if isinstance(call.func, ast.Name) and call.func.id == "print":
-                bpf_printk_emitter(call, module, builder, func)
-            if isinstance(call.func, ast.Name) and call.func.id == "ktime":
-                bpf_ktime_get_ns_emitter(call, module, builder, func)
+            if isinstance(call.func, ast.Name):
+                # check for helpers first
+                if call.func.id in helper_func_list:
+                    handle_helper_call(
+                        call, module, builder, func, local_sym_tab, map_sym_tab)
         elif isinstance(stmt, ast.Assign):
             handle_assign(module, builder, stmt, map_sym_tab, local_sym_tab)
         elif isinstance(stmt, ast.Return):