hardcoded func gen

pythonbpf/functions_pass.py

@@ -1,5 +1,78 @@
 from llvmlite import ir
 import ast
 
+
+def emit_function(module: ir.Module, name: str):
+    ret_type = ir.IntType(32)
+    ptr_type = ir.PointerType()
+    func_ty = ir.FunctionType(ret_type, [ptr_type])
+
+    func = ir.Function(module, func_ty, name)
+
+    param = func.args[0]
+    param.add_attribute("nocapture")
+
+    func.attributes.add("nounwind")
+#    func.attributes.add("\"frame-pointer\"=\"all\"")
+#    func.attributes.add("no-trapping-math", "true")
+#    func.attributes.add("stack-protector-buffer-size", "8")
+
+    block = func.append_basic_block(name="entry")
+    builder = ir.IRBuilder(block)
+    fmt_gvar = module.get_global("hello.____fmt")
+
+    if fmt_gvar is None:
+        # If you haven't created the format string global yet
+        print("Warning: Format string global not found")
+    else:
+        # Cast integer 6 to function pointer type
+        fn_type = ir.FunctionType(ir.IntType(
+            64), [ptr_type, ir.IntType(32)], var_arg=True)
+        fn_ptr_type = ir.PointerType(fn_type)
+        fn_addr = ir.Constant(ir.IntType(64), 6)
+        fn_ptr = builder.inttoptr(fn_addr, fn_ptr_type)
+        # Call the function
+        builder.call(fn_ptr, [fmt_gvar, ir.Constant(ir.IntType(32), 14)])
+
+    builder.ret(ir.Constant(ret_type, 0))
+
+    func.return_value.add_attribute("noundef")
+    func.linkage = "dso_local"
+    func.section = "kprobe/sys_clone"
+    print("function emitted:", name)
+    return func
+
+
 def functions_processing(tree, module):
-    pass
+    bpf_functions = []
+    helper_functions = []
+    for node in tree.body:
+        section_name = ""
+        if isinstance(node, ast.FunctionDef):
+            if len(node.decorator_list) == 1:
+                bpf_functions.append(node)
+                node.end_lineno
+            else:
+                # IDK why this check is needed, but whatever
+                if 'helper_functions' not in locals():
+                    helper_functions.append(node)
+
+    # TODO: implement helpers first
+
+    for func in bpf_functions:
+        dec = func.decorator_list[0]
+        if (
+            isinstance(dec, ast.Call)
+            and isinstance(dec.func, ast.Name)
+            and dec.func.id == "section"
+            and len(dec.args) == 1
+            and isinstance(dec.args[0], ast.Constant)
+            and isinstance(dec.args[0].value, str)
+        ):
+            section_name = dec.args[0].value
+        else:
+            print(f"ERROR: Invalid decorator for function {func.name}")
+            continue
+
+        # TODO: parse arguments and return type
+        emit_function(module, func.name + "func")