From fefd6840c88fc8c50d723ce3316d04d0c63e12be Mon Sep 17 00:00:00 2001
From: Pragyansh Chaturvedi <pragyansh.chaturvedi@canonical.com>
Date: Sun, 21 Sep 2025 17:50:58 +0530
Subject: [PATCH] finish perf_event_output helper integration

---
 pythonbpf/bpf_helper_handler.py | 37 +++++++++++++++++++++++++++------
 pythonbpf/structs_pass.py       | 20 +++++++++++++++++-
 2 files changed, 50 insertions(+), 7 deletions(-)

diff --git a/pythonbpf/bpf_helper_handler.py b/pythonbpf/bpf_helper_handler.py
index 95a8639..36297a6 100644
--- a/pythonbpf/bpf_helper_handler.py
+++ b/pythonbpf/bpf_helper_handler.py
@@ -359,12 +359,37 @@ def bpf_perf_event_output_handler(call, map_ptr, module, builder, func, local_sy
             data_type = local_var_metadata[data_name]
             if data_type in struct_sym_tab:
                 struct_info = struct_sym_tab[data_type]
-                data_size = 0
-                for field_type in struct_info["type"].elements:
-                    if isinstance(field_type, ir.IntType):
-                        data_size += field_type.width // 8
-                    elif isinstance(field_type, ir.PointerType):
-                        data_size += 8
+                size_val = ir.Constant(ir.IntType(64), struct_info["size"])
+            else:
+                raise ValueError(
+                    f"Struct type {data_type} for variable {data_name} not found in struct symbol table.")
+        else:
+            raise ValueError(
+                f"Metadata for variable {data_name} not found in local variable metadata.")
+
+        # BPF_F_CURRENT_CPU is 0
+        flags_val = ir.Constant(ir.IntType(64), 0)
+
+        map_void_ptr = builder.bitcast(map_ptr, ir.PointerType())
+        data_void_ptr = builder.bitcast(data_ptr, ir.PointerType())
+        fn_type = ir.FunctionType(
+            ir.IntType(64),
+            [ir.PointerType(ir.IntType(8)), ir.PointerType(), ir.IntType(64),
+             ir.PointerType(), ir.IntType(64)],
+            var_arg=False
+        )
+        fn_ptr_type = ir.PointerType(fn_type)
+
+        # helper id
+        fn_addr = ir.Constant(ir.IntType(64), 25)
+        fn_ptr = builder.inttoptr(fn_addr, fn_ptr_type)
+
+        result = builder.call(
+            fn_ptr, [ctx_ptr, map_void_ptr, flags_val, data_void_ptr, size_val], tail=False)
+        return result
+    else:
+        raise NotImplementedError(
+            "Only simple object names are supported as data in perf event output.")
 
 
 helper_func_list = {
diff --git a/pythonbpf/structs_pass.py b/pythonbpf/structs_pass.py
index 6574af0..fbe06ed 100644
--- a/pythonbpf/structs_pass.py
+++ b/pythonbpf/structs_pass.py
@@ -31,9 +31,27 @@ def process_bpf_struct(cls_node, module):
             field_names.append(item.target.id)
             field_types.append(ctypes_to_ir(item.annotation.id))
 
+    curr_offset = 0
+    for ftype in field_types:
+        if isinstance(ftype, ir.IntType):
+            fsize = ftype.width // 8
+            alignment = fsize
+        elif isinstance(ftype, ir.PointerType):
+            fsize = 8
+            alignment = 8
+        else:
+            print(f"Unsupported field type in struct {struct_name}")
+            return
+        padding = (alignment - (curr_offset % alignment)) % alignment
+        curr_offset += padding
+        curr_offset += fsize
+    final_padding = (8 - (curr_offset % 8)) % 8
+    total_size = curr_offset + final_padding
+
     struct_type = ir.LiteralStructType(field_types)
     structs_sym_tab[struct_name] = {
         "type": struct_type,
-        "fields": {name: idx for idx, name in enumerate(field_names)}
+        "fields": {name: idx for idx, name in enumerate(field_names)},
+        "size": total_size
     }
     print(f"Created struct {struct_name} with fields {field_names}")