Initial plan

pythonbpf/allocation_pass.py

@@ -118,6 +118,18 @@ def _allocate_for_call(
             local_sym_tab[var_name] = LocalSymbol(var, struct_info.ir_type, call_type)
             logger.info(f"Pre-allocated {var_name} for struct {call_type}")
 
+        elif VmlinuxHandlerRegistry.is_vmlinux_struct(call_type):
+            # When calling struct_name(pointer), we're doing a cast, not construction
+            # So we allocate as a pointer (i64) not as the actual struct
+            var = builder.alloca(ir.IntType(64), name=var_name)
+            var.align = 8
+            local_sym_tab[var_name] = LocalSymbol(
+                var, ir.IntType(64), VmlinuxHandlerRegistry.get_struct_type(call_type)
+            )
+            logger.info(
+                f"Pre-allocated {var_name} for vmlinux struct pointer cast to {call_type}"
+            )
+
         else:
             logger.warning(f"Unknown call type for allocation: {call_type}")
 
@@ -325,13 +337,6 @@ def _allocate_for_attribute(builder, var_name, rval, local_sym_tab, structs_sym_
                 VmlinuxHandlerRegistry.get_field_type(vmlinux_struct_name, field_name)
             )
             field_ir, field = field_type
-            # TODO: For now, we only support integer type allocations.
-            # This always assumes first argument of function to be the context struct
-            base_ptr = builder.function.args[0]
-            local_sym_tab[
-                struct_var
-            ].var = base_ptr  # This is repurposing of var to store the pointer of the base type
-            local_sym_tab[struct_var].ir_type = field_ir
 
             # Determine the actual IR type based on the field's type
             actual_ir_type = None
@@ -386,12 +391,14 @@ def _allocate_for_attribute(builder, var_name, rval, local_sym_tab, structs_sym_
                 )
                 actual_ir_type = ir.IntType(64)
 
-            # Allocate with the actual IR type, not the GlobalVariable
+            # Allocate with the actual IR type
             var = _allocate_with_type(builder, var_name, actual_ir_type)
-            local_sym_tab[var_name] = LocalSymbol(var, actual_ir_type, field)
+            local_sym_tab[var_name] = LocalSymbol(
+                var, actual_ir_type, field
+            )  # <-- Store Field metadata
 
             logger.info(
-                f"Pre-allocated {var_name} from vmlinux struct {vmlinux_struct_name}.{field_name}"
+                f"Pre-allocated {var_name} as {actual_ir_type} from vmlinux struct {vmlinux_struct_name}.{field_name}"
             )
             return
         else:

pythonbpf/assign_pass.py

@@ -1,5 +1,7 @@
 import ast
 import logging
+from inspect import isclass
+
 from llvmlite import ir
 from pythonbpf.expr import eval_expr
 from pythonbpf.helper import emit_probe_read_kernel_str_call
@@ -148,8 +150,30 @@ def handle_variable_assignment(
         return False
 
     val, val_type = val_result
-    logger.info(f"Evaluated value for {var_name}: {val} of type {val_type}, {var_type}")
+    logger.info(
+        f"Evaluated value for {var_name}: {val} of type {val_type}, expected {var_type}"
+    )
+
     if val_type != var_type:
+        # Handle vmlinux struct pointers - they're represented as Python classes but are i64 pointers
+        if isclass(val_type) and (val_type.__module__ == "vmlinux"):
+            logger.info("Handling vmlinux struct pointer assignment")
+            # vmlinux struct pointers: val is a pointer, need to convert to i64
+            if isinstance(var_type, ir.IntType) and var_type.width == 64:
+                # Convert pointer to i64 using ptrtoint
+                if isinstance(val.type, ir.PointerType):
+                    val = builder.ptrtoint(val, ir.IntType(64))
+                    logger.info(
+                        "Converted vmlinux struct pointer to i64 using ptrtoint"
+                    )
+                builder.store(val, var_ptr)
+                logger.info(f"Assigned vmlinux struct pointer to {var_name} (i64)")
+                return True
+            else:
+                logger.error(
+                    f"Type mismatch: vmlinux struct pointer requires i64, got {var_type}"
+                )
+                return False
         if isinstance(val_type, Field):
             logger.info("Handling assignment to struct field")
             # Special handling for struct_xdp_md i32 fields that are zero-extended to i64

pythonbpf/expr/expr_pass.py

@@ -12,8 +12,8 @@ from .type_normalization import (
     get_base_type_and_depth,
     deref_to_depth,
 )
-from pythonbpf.vmlinux_parser.assignment_info import Field
 from .vmlinux_registry import VmlinuxHandlerRegistry
+from ..vmlinux_parser.dependency_node import Field
 
 logger: Logger = logging.getLogger(__name__)
 
@@ -89,8 +89,16 @@ def _handle_attribute_expr(
                     return vmlinux_result
                 else:
                     raise RuntimeError("Vmlinux struct did not process successfully")
-            metadata = structs_sym_tab[var_metadata]
-            if attr_name in metadata.fields:
+
+            elif isinstance(var_metadata, Field):
+                logger.error(
+                    f"Cannot access field '{attr_name}' on already-loaded field value '{var_name}'"
+                )
+                return None
+
+            # Regular user-defined struct
+            metadata = structs_sym_tab.get(var_metadata)
+            if metadata and attr_name in metadata.fields:
                 gep = metadata.gep(builder, var_ptr, attr_name)
                 val = builder.load(gep)
                 field_type = metadata.field_type(attr_name)
@@ -525,6 +533,66 @@ def _handle_boolean_op(
         return None
 
 
+# ============================================================================
+# VMLinux casting
+# ============================================================================
+
+
+def _handle_vmlinux_cast(
+    func,
+    module,
+    builder,
+    expr,
+    local_sym_tab,
+    map_sym_tab,
+    structs_sym_tab=None,
+):
+    # handle expressions such as struct_request(ctx.di) where struct_request is a vmlinux
+    # struct and ctx.di is a pointer to a struct but is actually represented as a c_uint64
+    # which needs to be cast to a pointer. This is also a field of another vmlinux struct
+    """Handle vmlinux struct cast expressions like struct_request(ctx.di)."""
+    if len(expr.args) != 1:
+        logger.info("vmlinux struct cast takes exactly one argument")
+        return None
+
+    # Get the struct name
+    struct_name = expr.func.id
+
+    # Evaluate the argument (e.g., ctx.di which is a c_uint64)
+    arg_result = eval_expr(
+        func,
+        module,
+        builder,
+        expr.args[0],
+        local_sym_tab,
+        map_sym_tab,
+        structs_sym_tab,
+    )
+
+    if arg_result is None:
+        logger.info("Failed to evaluate argument to vmlinux struct cast")
+        return None
+
+    arg_val, arg_type = arg_result
+    # Get the vmlinux struct type
+    vmlinux_struct_type = VmlinuxHandlerRegistry.get_struct_type(struct_name)
+    if vmlinux_struct_type is None:
+        logger.error(f"Failed to get vmlinux struct type for {struct_name}")
+        return None
+    # Cast the integer/value to a pointer to the struct
+    # If arg_val is an integer type, we need to inttoptr it
+    ptr_type = ir.PointerType()
+    # TODO: add a integer check here later
+    if ctypes_to_ir(arg_type.type.__name__):
+        # Cast integer to pointer
+        casted_ptr = builder.inttoptr(arg_val, ptr_type)
+    else:
+        logger.error(f"Unsupported type for vmlinux cast: {arg_type}")
+        return None
+
+    return casted_ptr, vmlinux_struct_type
+
+
 # ============================================================================
 # Expression Dispatcher
 # ============================================================================
@@ -545,6 +613,18 @@ def eval_expr(
     elif isinstance(expr, ast.Constant):
         return _handle_constant_expr(module, builder, expr)
     elif isinstance(expr, ast.Call):
+        if isinstance(expr.func, ast.Name) and VmlinuxHandlerRegistry.is_vmlinux_struct(
+            expr.func.id
+        ):
+            return _handle_vmlinux_cast(
+                func,
+                module,
+                builder,
+                expr,
+                local_sym_tab,
+                map_sym_tab,
+                structs_sym_tab,
+            )
         if isinstance(expr.func, ast.Name) and expr.func.id == "deref":
             return _handle_deref_call(expr, local_sym_tab, builder)
 

pythonbpf/helper/__init__.py

@@ -1,6 +1,10 @@
 from .helper_registry import HelperHandlerRegistry
 from .helper_utils import reset_scratch_pool
-from .bpf_helper_handler import handle_helper_call, emit_probe_read_kernel_str_call
+from .bpf_helper_handler import (
+    handle_helper_call,
+    emit_probe_read_kernel_str_call,
+    emit_probe_read_kernel_call,
+)
 from .helpers import (
     ktime,
     pid,
@@ -74,6 +78,7 @@ __all__ = [
     "reset_scratch_pool",
     "handle_helper_call",
     "emit_probe_read_kernel_str_call",
+    "emit_probe_read_kernel_call",
     "ktime",
     "pid",
     "deref",

pythonbpf/helper/bpf_helper_handler.py

@@ -34,6 +34,7 @@ class BPFHelperID(Enum):
     BPF_PERF_EVENT_OUTPUT = 25
     BPF_GET_STACK = 67
     BPF_PROBE_READ_KERNEL_STR = 115
+    BPF_PROBE_READ_KERNEL = 113
     BPF_RINGBUF_OUTPUT = 130
     BPF_RINGBUF_RESERVE = 131
     BPF_RINGBUF_SUBMIT = 132
@@ -574,6 +575,75 @@ def bpf_probe_read_kernel_str_emitter(
     return result, ir.IntType(64)
 
 
+def emit_probe_read_kernel_call(builder, dst_ptr, dst_size, src_ptr):
+    """Emit LLVM IR call to bpf_probe_read_kernel"""
+
+    fn_type = ir.FunctionType(
+        ir.IntType(64),
+        [ir.PointerType(), ir.IntType(32), ir.PointerType()],
+        var_arg=False,
+    )
+    fn_ptr = builder.inttoptr(
+        ir.Constant(ir.IntType(64), BPFHelperID.BPF_PROBE_READ_KERNEL.value),
+        ir.PointerType(fn_type),
+    )
+
+    result = builder.call(
+        fn_ptr,
+        [
+            builder.bitcast(dst_ptr, ir.PointerType()),
+            ir.Constant(ir.IntType(32), dst_size),
+            builder.bitcast(src_ptr, ir.PointerType()),
+        ],
+        tail=False,
+    )
+
+    logger.info(f"Emitted bpf_probe_read_kernel (size={dst_size})")
+    return result
+
+
+@HelperHandlerRegistry.register(
+    "probe_read_kernel",
+    param_types=[
+        ir.PointerType(ir.IntType(8)),
+        ir.PointerType(ir.IntType(8)),
+    ],
+    return_type=ir.IntType(64),
+)
+def bpf_probe_read_kernel_emitter(
+    call,
+    map_ptr,
+    module,
+    builder,
+    func,
+    local_sym_tab=None,
+    struct_sym_tab=None,
+    map_sym_tab=None,
+):
+    """Emit LLVM IR for bpf_probe_read_kernel helper."""
+
+    if len(call.args) != 2:
+        raise ValueError(
+            f"probe_read_kernel expects 2 args (dst, src), got {len(call.args)}"
+        )
+
+    # Get destination buffer (char array -> i8*)
+    dst_ptr, dst_size = get_or_create_ptr_from_arg(
+        func, module, call.args[0], builder, local_sym_tab, map_sym_tab, struct_sym_tab
+    )
+
+    # Get source pointer (evaluate expression)
+    src_ptr, src_type = get_ptr_from_arg(
+        call.args[1], func, module, builder, local_sym_tab, map_sym_tab, struct_sym_tab
+    )
+
+    # Emit the helper call
+    result = emit_probe_read_kernel_call(builder, dst_ptr, dst_size, src_ptr)
+
+    logger.info(f"Emitted bpf_probe_read_kernel (size={dst_size})")
+    return result, ir.IntType(64)
+
+
 @HelperHandlerRegistry.register(
     "random",
     param_types=[],

pythonbpf/type_deducer.py

@@ -17,7 +17,6 @@ mapping = {
     "c_ulong": ir.IntType(64),
     "c_longlong": ir.IntType(64),
     "c_uint": ir.IntType(32),
-    "c_int": ir.IntType(32),
     # Not so sure about this one
     "str": ir.PointerType(ir.IntType(8)),
 }

pythonbpf/vmlinux_parser/class_handler.py

@@ -16,6 +16,33 @@ def get_module_symbols(module_name: str):
     return [name for name in dir(imported_module)], imported_module
 
 
+def unwrap_pointer_type(type_obj: Any) -> Any:
+    """
+    Recursively unwrap all pointer layers to get the base type.
+
+    This handles multiply nested pointers like LP_LP_struct_attribute_group
+    and returns the base type (struct_attribute_group).
+
+    Stops unwrapping when reaching a non-pointer type (one without _type_ attribute).
+
+    Args:
+        type_obj: The type object to unwrap
+
+    Returns:
+        The base type after unwrapping all pointer layers
+    """
+    current_type = type_obj
+    # Keep unwrapping while it's a pointer/array type (has _type_)
+    # But stop if _type_ is just a string or basic type marker
+    while hasattr(current_type, "_type_"):
+        next_type = current_type._type_
+        # Stop if _type_ is a string (like 'c' for c_char)
+        if isinstance(next_type, str):
+            break
+        current_type = next_type
+    return current_type
+
+
 def process_vmlinux_class(
     node,
     llvm_module,
@@ -158,13 +185,90 @@ def process_vmlinux_post_ast(
                         if hasattr(elem_type, "_length_") and is_complex_type:
                             type_length = elem_type._length_
 
-                        if containing_type.__module__ == "vmlinux":
-                            new_dep_node.add_dependent(
-                                elem_type._type_.__name__
-                                if hasattr(elem_type._type_, "__name__")
-                                else str(elem_type._type_)
+                        # Unwrap all pointer layers to get the base type for dependency tracking
+                        base_type = unwrap_pointer_type(elem_type)
+                        base_type_module = getattr(base_type, "__module__", None)
+
+                        if base_type_module == "vmlinux":
+                            base_type_name = (
+                                base_type.__name__
+                                if hasattr(base_type, "__name__")
+                                else str(base_type)
+                            )
+                            # ONLY add vmlinux types as dependencies
+                            new_dep_node.add_dependent(base_type_name)
+
+                            logger.debug(
+                                f"{containing_type} containing type of parent {elem_name} with {elem_type} and ctype {ctype_complex_type} and length {type_length}"
+                            )
+                            new_dep_node.set_field_containing_type(
+                                elem_name, containing_type
+                            )
+                            new_dep_node.set_field_type_size(elem_name, type_length)
+                            new_dep_node.set_field_ctype_complex_type(
+                                elem_name, ctype_complex_type
+                            )
+                            new_dep_node.set_field_type(elem_name, elem_type)
+
+                            # Check the containing_type module to decide whether to recurse
+                            containing_type_module = getattr(
+                                containing_type, "__module__", None
+                            )
+                            if containing_type_module == "vmlinux":
+                                # Also unwrap containing_type to get base type name
+                                base_containing_type = unwrap_pointer_type(
+                                    containing_type
+                                )
+                                containing_type_name = (
+                                    base_containing_type.__name__
+                                    if hasattr(base_containing_type, "__name__")
+                                    else str(base_containing_type)
+                                )
+
+                                # Check for self-reference or already processed
+                                if containing_type_name == current_symbol_name:
+                                    # Self-referential pointer
+                                    logger.debug(
+                                        f"Self-referential pointer in {current_symbol_name}.{elem_name}"
+                                    )
+                                    new_dep_node.set_field_ready(elem_name, True)
+                                elif handler.has_node(containing_type_name):
+                                    # Already processed
+                                    logger.debug(
+                                        f"Reusing already processed {containing_type_name}"
+                                    )
+                                    new_dep_node.set_field_ready(elem_name, True)
+                                else:
+                                    # Process recursively - use base containing type, not the pointer wrapper
+                                    new_dep_node.add_dependent(containing_type_name)
+                                    process_vmlinux_post_ast(
+                                        base_containing_type,
+                                        llvm_handler,
+                                        handler,
+                                        processing_stack,
+                                    )
+                                    new_dep_node.set_field_ready(elem_name, True)
+                            elif (
+                                containing_type_module == ctypes.__name__
+                                or containing_type_module is None
+                            ):
+                                logger.debug(
+                                    f"Processing ctype internal{containing_type}"
+                                )
+                                new_dep_node.set_field_ready(elem_name, True)
+                            else:
+                                raise TypeError(
+                                    f"Module not supported in recursive resolution: {containing_type_module}"
+                                )
+                        elif (
+                            base_type_module == ctypes.__name__
+                            or base_type_module is None
+                        ):
+                            # Handle ctypes or types with no module (like some internal ctypes types)
+                            # DO NOT add ctypes as dependencies - just set field metadata and mark ready
+                            logger.debug(
+                                f"Base type {base_type} is ctypes - NOT adding as dependency, just processing field"
                             )
-                        elif containing_type.__module__ == ctypes.__name__:
                             if isinstance(elem_type, type):
                                 if issubclass(elem_type, ctypes.Array):
                                     ctype_complex_type = ctypes.Array
@@ -176,57 +280,20 @@ def process_vmlinux_post_ast(
                                     )
                             else:
                                 raise TypeError("Unsupported ctypes subclass")
-                        else:
-                            raise ImportError(
-                                f"Unsupported module of {containing_type}"
-                            )
-                        logger.debug(
-                            f"{containing_type} containing type of parent {elem_name} with {elem_type} and ctype {ctype_complex_type} and length {type_length}"
-                        )
-                        new_dep_node.set_field_containing_type(
-                            elem_name, containing_type
-                        )
-                        new_dep_node.set_field_type_size(elem_name, type_length)
-                        new_dep_node.set_field_ctype_complex_type(
-                            elem_name, ctype_complex_type
-                        )
-                        new_dep_node.set_field_type(elem_name, elem_type)
-                        if containing_type.__module__ == "vmlinux":
-                            containing_type_name = (
-                                containing_type.__name__
-                                if hasattr(containing_type, "__name__")
-                                else str(containing_type)
-                            )
 
-                            # Check for self-reference or already processed
-                            if containing_type_name == current_symbol_name:
-                                # Self-referential pointer
-                                logger.debug(
-                                    f"Self-referential pointer in {current_symbol_name}.{elem_name}"
-                                )
-                                new_dep_node.set_field_ready(elem_name, True)
-                            elif handler.has_node(containing_type_name):
-                                # Already processed
-                                logger.debug(
-                                    f"Reusing already processed {containing_type_name}"
-                                )
-                                new_dep_node.set_field_ready(elem_name, True)
-                            else:
-                                # Process recursively - THIS WAS MISSING
-                                new_dep_node.add_dependent(containing_type_name)
-                                process_vmlinux_post_ast(
-                                    containing_type,
-                                    llvm_handler,
-                                    handler,
-                                    processing_stack,
-                                )
-                                new_dep_node.set_field_ready(elem_name, True)
-                        elif containing_type.__module__ == ctypes.__name__:
-                            logger.debug(f"Processing ctype internal{containing_type}")
+                            # Set field metadata but DO NOT add dependency or recurse
+                            new_dep_node.set_field_containing_type(
+                                elem_name, containing_type
+                            )
+                            new_dep_node.set_field_type_size(elem_name, type_length)
+                            new_dep_node.set_field_ctype_complex_type(
+                                elem_name, ctype_complex_type
+                            )
+                            new_dep_node.set_field_type(elem_name, elem_type)
                             new_dep_node.set_field_ready(elem_name, True)
                         else:
-                            raise TypeError(
-                                "Module not supported in recursive resolution"
+                            raise ImportError(
+                                f"Unsupported module of {base_type}: {base_type_module}"
                             )
                     else:
                         new_dep_node.add_dependent(
@@ -245,9 +312,12 @@ def process_vmlinux_post_ast(
                     raise ValueError(
                         f"{elem_name} with type {elem_type} from module {module_name} not supported in recursive resolver"
                     )
-
+    elif module_name == ctypes.__name__ or module_name is None:
+        # Handle ctypes types - these don't need processing, just return
+        logger.debug(f"Skipping ctypes type {current_symbol_name}")
+        return True
     else:
-        raise ImportError("UNSUPPORTED Module")
+        raise ImportError(f"UNSUPPORTED Module {module_name}")
 
     logger.info(
         f"{current_symbol_name} processed and handler readiness {handler.is_ready}"

pythonbpf/vmlinux_parser/import_detector.py

@@ -11,7 +11,9 @@ from .class_handler import process_vmlinux_class
 logger = logging.getLogger(__name__)
 
 
-def detect_import_statement(tree: ast.AST) -> list[tuple[str, ast.ImportFrom]]:
+def detect_import_statement(
+    tree: ast.AST,
+) -> list[tuple[str, ast.ImportFrom, str, str]]:
     """
     Parse AST and detect import statements from vmlinux.
 
@@ -25,7 +27,7 @@ def detect_import_statement(tree: ast.AST) -> list[tuple[str, ast.ImportFrom]]:
         List of tuples containing (module_name, imported_item) for each vmlinux import
 
     Raises:
-        SyntaxError: If multiple imports from vmlinux are attempted or import * is used
+        SyntaxError: If import * is used
     """
     vmlinux_imports = []
 
@@ -40,28 +42,19 @@ def detect_import_statement(tree: ast.AST) -> list[tuple[str, ast.ImportFrom]]:
                         "Please import specific types explicitly."
                     )
 
-                # Check for multiple imports: from vmlinux import A, B, C
-                if len(node.names) > 1:
-                    imported_names = [alias.name for alias in node.names]
-                    raise SyntaxError(
-                        f"Multiple imports from vmlinux are not supported. "
-                        f"Found: {', '.join(imported_names)}. "
-                        f"Please use separate import statements for each type."
-                    )
-
                 # Check if no specific import is specified (should not happen with valid Python)
                 if len(node.names) == 0:
                     raise SyntaxError(
                         "Import from vmlinux must specify at least one type."
                     )
 
-                # Valid single import
+                # Support multiple imports: from vmlinux import A, B, C
                 for alias in node.names:
                     import_name = alias.name
-                    # Use alias if provided, otherwise use the original name (commented)
-                    # as_name = alias.asname if alias.asname else alias.name
-                    vmlinux_imports.append(("vmlinux", node))
-                    logger.info(f"Found vmlinux import: {import_name}")
+                    # Use alias if provided, otherwise use the original name
+                    as_name = alias.asname if alias.asname else alias.name
+                    vmlinux_imports.append(("vmlinux", node, import_name, as_name))
+                    logger.info(f"Found vmlinux import: {import_name} as {as_name}")
 
         # Handle "import vmlinux" statements (not typical but should be rejected)
         elif isinstance(node, ast.Import):
@@ -103,40 +96,37 @@ def vmlinux_proc(tree: ast.AST, module):
     with open(source_file, "r") as f:
         mod_ast = ast.parse(f.read(), filename=source_file)
 
-    for import_mod, import_node in import_statements:
-        for alias in import_node.names:
-            imported_name = alias.name
-            found = False
-            for mod_node in mod_ast.body:
-                if (
-                    isinstance(mod_node, ast.ClassDef)
-                    and mod_node.name == imported_name
-                ):
-                    process_vmlinux_class(mod_node, module, handler)
-                    found = True
-                    break
-                if isinstance(mod_node, ast.Assign):
-                    for target in mod_node.targets:
-                        if isinstance(target, ast.Name) and target.id == imported_name:
-                            process_vmlinux_assign(mod_node, module, assignments)
-                            found = True
-                            break
-                if found:
-                    break
-            if not found:
-                logger.info(
-                    f"{imported_name} not found as ClassDef or Assign in vmlinux"
-                )
+    for import_mod, import_node, imported_name, as_name in import_statements:
+        found = False
+        for mod_node in mod_ast.body:
+            if isinstance(mod_node, ast.ClassDef) and mod_node.name == imported_name:
+                process_vmlinux_class(mod_node, module, handler)
+                found = True
+                break
+            if isinstance(mod_node, ast.Assign):
+                for target in mod_node.targets:
+                    if isinstance(target, ast.Name) and target.id == imported_name:
+                        process_vmlinux_assign(mod_node, module, assignments, as_name)
+                        found = True
+                        break
+            if found:
+                break
+        if not found:
+            logger.info(f"{imported_name} not found as ClassDef or Assign in vmlinux")
 
     IRGenerator(module, handler, assignments)
     return assignments
 
 
-def process_vmlinux_assign(node, module, assignments: dict[str, AssignmentInfo]):
+def process_vmlinux_assign(
+    node, module, assignments: dict[str, AssignmentInfo], target_name=None
+):
     """Process assignments from vmlinux module."""
     # Only handle single-target assignments
     if len(node.targets) == 1 and isinstance(node.targets[0], ast.Name):
-        target_name = node.targets[0].id
+        # Use provided target_name (for aliased imports) or fall back to original name
+        if target_name is None:
+            target_name = node.targets[0].id
 
         # Handle constant value assignments
         if isinstance(node.value, ast.Constant):

pythonbpf/vmlinux_parser/ir_gen/debug_info_gen.py

@@ -21,7 +21,7 @@ def debug_info_generation(
         generated_debug_info: List of tuples (struct, debug_info) to track generated debug info
 
     Returns:
-        The generated global variable debug info
+        The generated global variable debug info, or None for unsupported types
     """
     # Set up debug info generator
     generator = DebugInfoGenerator(llvm_module)
@@ -31,23 +31,42 @@ def debug_info_generation(
         if existing_struct.name == struct.name:
             return debug_info
 
+    # Check if this is a union (not supported yet)
+    if not struct.name.startswith("struct_"):
+        logger.warning(f"Skipping debug info generation for union: {struct.name}")
+        # Create a minimal forward declaration for unions
+        union_type = generator.create_struct_type(
+            [], struct.__sizeof__() * 8, is_distinct=True
+        )
+        return union_type
+
     # Process all fields and create members for the struct
     members = []
-    for field_name, field in struct.fields.items():
-        # Get appropriate debug type for this field
-        field_type = _get_field_debug_type(
-            field_name, field, generator, struct, generated_debug_info
-        )
-        # Create struct member with proper offset
-        member = generator.create_struct_member_vmlinux(
-            field_name, field_type, field.offset * 8
-        )
-        members.append(member)
 
-    if struct.name.startswith("struct_"):
-        struct_name = struct.name.removeprefix("struct_")
-    else:
-        raise ValueError("Unions are not supported in the current version")
+    sorted_fields = sorted(struct.fields.items(), key=lambda item: item[1].offset)
+
+    for field_name, field in sorted_fields:
+        try:
+            # Get appropriate debug type for this field
+            field_type = _get_field_debug_type(
+                field_name, field, generator, struct, generated_debug_info
+            )
+
+            # Ensure field_type is a tuple
+            if not isinstance(field_type, tuple) or len(field_type) != 2:
+                logger.error(f"Invalid field_type for {field_name}: {field_type}")
+                continue
+
+            # Create struct member with proper offset
+            member = generator.create_struct_member_vmlinux(
+                field_name, field_type, field.offset * 8
+            )
+            members.append(member)
+        except Exception as e:
+            logger.error(f"Failed to process field {field_name} in {struct.name}: {e}")
+            continue
+
+    struct_name = struct.name.removeprefix("struct_")
     # Create struct type with all members
     struct_type = generator.create_struct_type_with_name(
         struct_name, members, struct.__sizeof__() * 8, is_distinct=True
@@ -74,11 +93,19 @@ def _get_field_debug_type(
         generated_debug_info: List of already generated debug info
 
     Returns:
-        The debug info type for this field
+        A tuple of (debug_type, size_in_bits)
     """
-    # Handle complex types (arrays, pointers)
+    # Handle complex types (arrays, pointers, function pointers)
     if field.ctype_complex_type is not None:
-        if issubclass(field.ctype_complex_type, ctypes.Array):
+        # Handle function pointer types (CFUNCTYPE)
+        if callable(field.ctype_complex_type):
+            # Function pointers are represented as void pointers
+            logger.warning(
+                f"Field {field_name} is a function pointer, using void pointer"
+            )
+            void_ptr = generator.create_pointer_type(None, 64)
+            return void_ptr, 64
+        elif issubclass(field.ctype_complex_type, ctypes.Array):
             # Handle array types
             element_type, base_type_size = _get_basic_debug_type(
                 field.containing_type, generator
@@ -100,11 +127,13 @@ def _get_field_debug_type(
         for existing_struct, debug_info in generated_debug_info:
             if existing_struct.name == struct_name:
                 # Use existing debug info
-                return debug_info, existing_struct.__sizeof__()
+                return debug_info, existing_struct.__sizeof__() * 8
 
         # If not found, create a forward declaration
         # This will be completed when the actual struct is processed
-        logger.warning("Forward declaration in struct created")
+        logger.info(
+            f"Forward declaration created for {struct_name} in {parent_struct.name}"
+        )
         forward_type = generator.create_struct_type([], 0, is_distinct=True)
         return forward_type, 0
 

pythonbpf/vmlinux_parser/ir_gen/ir_generation.py

@@ -11,6 +11,10 @@ logger = logging.getLogger(__name__)
 
 
 class IRGenerator:
+    # This field keeps track of the non_struct names to avoid duplicate name errors.
+    type_number = 0
+    unprocessed_store: list[str] = []
+
     # get the assignments dict and add this stuff to it.
     def __init__(self, llvm_module, handler: DependencyHandler, assignments):
         self.llvm_module = llvm_module
@@ -129,7 +133,19 @@ class IRGenerator:
 
         for field_name, field in struct.fields.items():
             # does not take arrays and similar types into consideration yet.
-            if field.ctype_complex_type is not None and issubclass(
+            if callable(field.ctype_complex_type):
+                # Function pointer case - generate a simple field accessor
+                field_co_re_name, returned = self._struct_name_generator(
+                    struct, field, field_index
+                )
+                field_index += 1
+                globvar = ir.GlobalVariable(
+                    self.llvm_module, ir.IntType(64), name=field_co_re_name
+                )
+                globvar.linkage = "external"
+                globvar.set_metadata("llvm.preserve.access.index", debug_info)
+                self.generated_field_names[struct.name][field_name] = globvar
+            elif field.ctype_complex_type is not None and issubclass(
                 field.ctype_complex_type, ctypes.Array
             ):
                 array_size = field.type_size
@@ -137,7 +153,7 @@ class IRGenerator:
                 if containing_type.__module__ == ctypes.__name__:
                     containing_type_size = ctypes.sizeof(containing_type)
                     if array_size == 0:
-                        field_co_re_name = self._struct_name_generator(
+                        field_co_re_name, returned = self._struct_name_generator(
                             struct, field, field_index, True, 0, containing_type_size
                         )
                         globvar = ir.GlobalVariable(
@@ -149,7 +165,7 @@ class IRGenerator:
                         field_index += 1
                         continue
                     for i in range(0, array_size):
-                        field_co_re_name = self._struct_name_generator(
+                        field_co_re_name, returned = self._struct_name_generator(
                             struct, field, field_index, True, i, containing_type_size
                         )
                         globvar = ir.GlobalVariable(
@@ -163,12 +179,28 @@ class IRGenerator:
                 array_size = field.type_size
                 containing_type = field.containing_type
                 if containing_type.__module__ == "vmlinux":
-                    containing_type_size = self.handler[
-                        containing_type.__name__
-                    ].current_offset
-                    for i in range(0, array_size):
-                        field_co_re_name = self._struct_name_generator(
-                            struct, field, field_index, True, i, containing_type_size
+                    # Unwrap all pointer layers to get the base struct type
+                    base_containing_type = containing_type
+                    while hasattr(base_containing_type, "_type_"):
+                        next_type = base_containing_type._type_
+                        # Stop if _type_ is a string (like 'c' for c_char)
+                        # TODO: stacked pointers not handl;ing ctypes check here as well
+                        if isinstance(next_type, str):
+                            break
+                        base_containing_type = next_type
+
+                    # Get the base struct name
+                    base_struct_name = (
+                        base_containing_type.__name__
+                        if hasattr(base_containing_type, "__name__")
+                        else str(base_containing_type)
+                    )
+
+                    # Look up the size using the base struct name
+                    containing_type_size = self.handler[base_struct_name].current_offset
+                    if array_size == 0:
+                        field_co_re_name, returned = self._struct_name_generator(
+                            struct, field, field_index, True, 0, containing_type_size
                         )
                         globvar = ir.GlobalVariable(
                             self.llvm_module, ir.IntType(64), name=field_co_re_name
@@ -176,9 +208,30 @@ class IRGenerator:
                         globvar.linkage = "external"
                         globvar.set_metadata("llvm.preserve.access.index", debug_info)
                         self.generated_field_names[struct.name][field_name] = globvar
-                    field_index += 1
+                        field_index += 1
+                    else:
+                        for i in range(0, array_size):
+                            field_co_re_name, returned = self._struct_name_generator(
+                                struct,
+                                field,
+                                field_index,
+                                True,
+                                i,
+                                containing_type_size,
+                            )
+                            globvar = ir.GlobalVariable(
+                                self.llvm_module, ir.IntType(64), name=field_co_re_name
+                            )
+                            globvar.linkage = "external"
+                            globvar.set_metadata(
+                                "llvm.preserve.access.index", debug_info
+                            )
+                            self.generated_field_names[struct.name][field_name] = (
+                                globvar
+                            )
+                        field_index += 1
             else:
-                field_co_re_name = self._struct_name_generator(
+                field_co_re_name, returned = self._struct_name_generator(
                     struct, field, field_index
                 )
                 field_index += 1
@@ -198,7 +251,7 @@ class IRGenerator:
         is_indexed: bool = False,
         index: int = 0,
         containing_type_size: int = 0,
-    ) -> str:
+    ) -> tuple[str, bool]:
         # TODO: Does not support Unions as well as recursive pointer and array type naming
         if is_indexed:
             name = (
@@ -208,7 +261,7 @@ class IRGenerator:
                 + "$"
                 + f"0:{field_index}:{index}"
             )
-            return name
+            return name, True
         elif struct.name.startswith("struct_"):
             name = (
                 "llvm."
@@ -217,9 +270,18 @@ class IRGenerator:
                 + "$"
                 + f"0:{field_index}"
             )
-            return name
+            return name, True
         else:
-            print(self.handler[struct.name])
-            raise TypeError(
-                "Name generation cannot occur due to type name not starting with struct"
+            logger.warning(
+                "Blindly handling non-struct type to avoid type errors in vmlinux IR generation. Possibly a union."
             )
+            self.type_number += 1
+            unprocessed_type = "unprocessed_type_" + str(self.handler[struct.name].name)
+            if self.unprocessed_store.__contains__(unprocessed_type):
+                return unprocessed_type + "_" + str(self.type_number), False
+            else:
+                self.unprocessed_store.append(unprocessed_type)
+                return unprocessed_type, False
+            # raise TypeError(
+            #     "Name generation cannot occur due to type name not starting with struct"
+            # )

pythonbpf/vmlinux_parser/vmlinux_exports_handler.py

@@ -94,17 +94,140 @@ class VmlinuxHandler:
                 f"Attempting to access field {field_name} of possible vmlinux struct {struct_var_name}"
             )
             python_type: type = var_info.metadata
-            struct_name = python_type.__name__
-            globvar_ir, field_data = self.get_field_type(struct_name, field_name)
-            builder.function.args[0].type = ir.PointerType(ir.IntType(8))
-            field_ptr = self.load_ctx_field(
-                builder, builder.function.args[0], globvar_ir, field_data, struct_name
-            )
-            # Return pointer to field and field type
-            return field_ptr, field_data
+            # Check if this is a context field (ctx) or a cast struct
+            is_context_field = var_info.var is None
+
+            if is_context_field:
+                # Handle context field access (original behavior)
+                struct_name = python_type.__name__
+                globvar_ir, field_data = self.get_field_type(struct_name, field_name)
+                builder.function.args[0].type = ir.PointerType(ir.IntType(8))
+                field_ptr = self.load_ctx_field(
+                    builder,
+                    builder.function.args[0],
+                    globvar_ir,
+                    field_data,
+                    struct_name,
+                )
+                return field_ptr, field_data
+            else:
+                # Handle cast struct field access
+                struct_name = python_type.__name__
+                globvar_ir, field_data = self.get_field_type(struct_name, field_name)
+
+                # Handle cast struct field access (use bpf_probe_read_kernel)
+                # Load the struct pointer from the local variable
+                struct_ptr = builder.load(var_info.var)
+
+                # Use bpf_probe_read_kernel for non-context struct field access
+                field_value = self.load_struct_field(
+                    builder, struct_ptr, globvar_ir, field_data, struct_name
+                )
+                # Return field value and field type
+                return field_value, field_data
         else:
             raise RuntimeError("Variable accessed not found in symbol table")
 
+    @staticmethod
+    def load_struct_field(
+        builder, struct_ptr_int, offset_global, field_data, struct_name=None
+    ):
+        """
+        Generate LLVM IR to load a field from a regular (non-context) struct using bpf_probe_read_kernel.
+
+        Args:
+            builder: llvmlite IRBuilder instance
+            struct_ptr_int: The struct pointer as an i64 value (already loaded from alloca)
+            offset_global: Global variable containing the field offset (i64)
+            field_data: contains data about the field
+            struct_name: Name of the struct being accessed (optional)
+        Returns:
+            The loaded value
+        """
+
+        # Load the offset value
+        offset = builder.load(offset_global)
+
+        # Convert i64 to pointer type (BPF stores pointers as i64)
+        i8_ptr_type = ir.PointerType(ir.IntType(8))
+        struct_ptr = builder.inttoptr(struct_ptr_int, i8_ptr_type)
+
+        # GEP with offset to get field pointer
+        field_ptr = builder.gep(
+            struct_ptr,
+            [offset],
+            inbounds=False,
+        )
+
+        # Determine the appropriate field size based on field information
+        field_size_bytes = 8  # Default to 8 bytes (64-bit)
+        int_width = 64  # Default to 64-bit
+        needs_zext = False
+
+        if field_data is not None:
+            # Try to determine the size from field metadata
+            if field_data.type.__module__ == ctypes.__name__:
+                try:
+                    field_size_bytes = ctypes.sizeof(field_data.type)
+                    field_size_bits = field_size_bytes * 8
+
+                    if field_size_bits in [8, 16, 32, 64]:
+                        int_width = field_size_bits
+                        logger.info(
+                            f"Determined field size: {int_width} bits ({field_size_bytes} bytes)"
+                        )
+
+                        # Special handling for struct_xdp_md i32 fields
+                        if struct_name == "struct_xdp_md" and int_width == 32:
+                            needs_zext = True
+                            logger.info(
+                                "struct_xdp_md i32 field detected, will zero-extend to i64"
+                            )
+                    else:
+                        logger.warning(
+                            f"Unusual field size {field_size_bits} bits, using default 64"
+                        )
+                except Exception as e:
+                    logger.warning(
+                        f"Could not determine field size: {e}, using default 64"
+                    )
+
+            elif field_data.type.__module__ == "vmlinux":
+                # For pointers to structs or complex vmlinux types
+                if field_data.ctype_complex_type is not None and issubclass(
+                    field_data.ctype_complex_type, ctypes._Pointer
+                ):
+                    int_width = 64  # Pointers are always 64-bit
+                    field_size_bytes = 8
+                    logger.info("Field is a pointer type, using 64 bits")
+                else:
+                    logger.warning("Complex vmlinux field type, using default 64 bits")
+
+        # Allocate local storage for the field value
+        local_storage = builder.alloca(ir.IntType(int_width))
+        local_storage_i8_ptr = builder.bitcast(local_storage, i8_ptr_type)
+
+        # Use bpf_probe_read_kernel to safely read the field
+        # This generates:
+        #   %gep = getelementptr i8, ptr %struct_ptr, i64 %offset (already done above as field_ptr)
+        #   %passed = tail call ptr @llvm.bpf.passthrough.p0.p0(i32 2, ptr %gep)
+        #   %result = call i64 inttoptr (i64 113 to ptr)(ptr %local_storage, i32 %size, ptr %passed)
+        from pythonbpf.helper import emit_probe_read_kernel_call
+
+        emit_probe_read_kernel_call(
+            builder, local_storage_i8_ptr, field_size_bytes, field_ptr
+        )
+
+        # Load the value from local storage
+        value = builder.load(local_storage)
+
+        # Zero-extend i32 to i64 if needed
+        if needs_zext:
+            value = builder.zext(value, ir.IntType(64))
+            logger.info("Zero-extended i32 value to i64")
+
+        return value
+
     @staticmethod
     def load_ctx_field(builder, ctx_arg, offset_global, field_data, struct_name=None):
         """

tests/c-form/Makefile

@@ -3,21 +3,20 @@ CFLAGS := -emit-llvm -target bpf -c
 
 SRC := $(wildcard *.bpf.c)
 LL := $(SRC:.bpf.c=.bpf.ll)
-LL2 := $(SRC:.bpf.c=.bpf.o2.ll)
 OBJ := $(SRC:.bpf.c=.bpf.o)
-
+LL0 := $(SRC:.bpf.c=.bpf.o0.ll)
 .PHONY: all clean
 
-all: $(LL) $(OBJ) $(LL2)
+all: $(LL) $(OBJ) $(LL0)
 
 %.bpf.o: %.bpf.c
 	$(BPF_CLANG) -O2 -g -target bpf -c $< -o $@
 
 %.bpf.ll: %.bpf.c
-	$(BPF_CLANG) -O0 $(CFLAGS) -g -S $< -o $@
+	$(BPF_CLANG) $(CFLAGS) -O2 -g -S $< -o $@
 
-%.bpf.o2.ll: %.bpf.c
-	$(BPF_CLANG) -O2 $(CFLAGS) -g -S $< -o $@
+%.bpf.o0.ll: %.bpf.c
+	$(BPF_CLANG) $(CFLAGS) -O0 -g -S $< -o $@
 
 clean:
-	rm -f $(LL) $(OBJ) $(LL2)
+	rm -f $(LL) $(OBJ) $(LL0)

tests/c-form/requests.bpf.c

@@ -0,0 +1,18 @@
+#include "vmlinux.h"
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+#include <bpf/bpf_core_read.h>
+
+char LICENSE[] SEC("license") = "GPL";
+
+SEC("kprobe/blk_mq_start_request")
+int example(struct pt_regs *ctx)
+{
+    u64 a = ctx->r15;
+    struct request *req = (struct request *)(ctx->di);
+    unsigned int something_ns = BPF_CORE_READ(req, timeout);
+    unsigned int data_len = BPF_CORE_READ(req, __data_len);
+    bpf_printk("data length %lld %ld %ld\n", data_len,  something_ns, a);
+
+    return 0;
+}

tests/c-form/requests2.bpf.c

@@ -0,0 +1,18 @@
+#include "vmlinux.h"
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+#include <bpf/bpf_core_read.h>
+
+char LICENSE[] SEC("license") = "GPL";
+
+SEC("kprobe/blk_mq_start_request")
+int example(struct pt_regs *ctx)
+{
+    u64 a = ctx->r15;
+    struct request *req = (struct request *)(ctx->di);
+    unsigned int something_ns = req->timeout;
+    unsigned int data_len = req->__data_len;
+    bpf_printk("data length %lld %ld %ld\n", data_len,  something_ns, a);
+
+    return 0;
+}

tests/failing_tests/vmlinux/assignment_handling.py

@@ -0,0 +1,22 @@
+from vmlinux import XDP_PASS
+from pythonbpf import bpf, section, bpfglobal, compile_to_ir
+import logging
+from ctypes import c_int64, c_void_p
+
+
+@bpf
+@section("kprobe/blk_mq_start_request")
+def example(ctx: c_void_p) -> c_int64:
+    d = XDP_PASS  # This gives an error, but
+    e = XDP_PASS + 0  # this does not
+    print(f"test1 {e} test2 {d}")
+    return c_int64(0)
+
+
+@bpf
+@bpfglobal
+def LICENSE() -> str:
+    return "GPL"
+
+
+compile_to_ir("assignment_handling.py", "assignment_handling.ll", loglevel=logging.INFO)

tests/passing_tests/vmlinux/requests.py

@@ -0,0 +1,27 @@
+from vmlinux import struct_request, struct_pt_regs
+from pythonbpf import bpf, section, bpfglobal, compile_to_ir, compile
+import logging
+from ctypes import c_int64
+
+
+@bpf
+@section("kprobe/blk_mq_start_request")
+def example(ctx: struct_pt_regs) -> c_int64:
+    a = ctx.r15
+    req = struct_request(ctx.di)
+    d = req.__data_len
+    b = ctx.r12
+    c = req.timeout
+    print(f"data length {d} and {c} and {a}")
+    print(f"ctx arg {b}")
+    return c_int64(0)
+
+
+@bpf
+@bpfglobal
+def LICENSE() -> str:
+    return "GPL"
+
+
+compile_to_ir("requests.py", "requests.ll", loglevel=logging.INFO)
+compile()

tests/passing_tests/vmlinux/requests2.py

@@ -0,0 +1,21 @@
+from vmlinux import struct_pt_regs
+from pythonbpf import bpf, section, bpfglobal, compile_to_ir
+import logging
+from ctypes import c_int64
+
+
+@bpf
+@section("kprobe/blk_mq_start_request")
+def example(ctx: struct_pt_regs) -> c_int64:
+    req = ctx.di
+    print(f"data length {req}")
+    return c_int64(0)
+
+
+@bpf
+@bpfglobal
+def LICENSE() -> str:
+    return "GPL"
+
+
+compile_to_ir("requests2.py", "requests2.ll", loglevel=logging.INFO)