Fix get_flags_val usage

pythonbpf/helper/__init__.py

@@ -12,6 +12,7 @@ from .helpers import (
     smp_processor_id,
     uid,
     skb_store_bytes,
+    get_stack,
     XDP_DROP,
     XDP_PASS,
 )
@@ -83,6 +84,7 @@ __all__ = [
     "smp_processor_id",
     "uid",
     "skb_store_bytes",
+    "get_stack",
     "XDP_DROP",
     "XDP_PASS",
 ]

pythonbpf/helper/bpf_helper_handler.py

@@ -32,6 +32,7 @@ class BPFHelperID(Enum):
     BPF_GET_CURRENT_UID_GID = 15
     BPF_GET_CURRENT_COMM = 16
     BPF_PERF_EVENT_OUTPUT = 25
+    BPF_GET_STACK = 67
     BPF_PROBE_READ_KERNEL_STR = 115
     BPF_RINGBUF_OUTPUT = 130
     BPF_RINGBUF_RESERVE = 131
@@ -805,7 +806,10 @@ def bpf_skb_store_bytes_emitter(
         flags_val = get_flags_val(call.args[3], builder, local_sym_tab)
     else:
         flags_val = 0
-    flags = ir.Constant(ir.IntType(64), flags_val)
+    if isinstance(flags_val, int):
+        flags = ir.Constant(ir.IntType(64), flags_val)
+    else:
+        flags = flags_val
     fn_type = ir.FunctionType(
         ir.IntType(64),
         args_signature,
@@ -921,8 +925,8 @@ def bpf_ringbuf_submit_emitter(
     )
 
     flags_const = get_flags_val(flags_arg, builder, local_sym_tab)
-    if not flags_arg:
-        flags_const = ir.Constant(ir.IntType(64), 0)
+    if isinstance(flags_const, int):
+        flags_const = ir.Constant(ir.IntType(64), flags_const)
 
     map_void_ptr = builder.bitcast(map_ptr, ir.PointerType())
     fn_type = ir.FunctionType(
@@ -940,6 +944,57 @@ def bpf_ringbuf_submit_emitter(
     return result, None
 
 
+@HelperHandlerRegistry.register(
+    "get_stack",
+    param_types=[ir.PointerType(ir.IntType(8)), ir.IntType(64)],
+    return_type=ir.IntType(64),
+)
+def bpf_get_stack_emitter(
+    call,
+    map_ptr,
+    module,
+    builder,
+    func,
+    local_sym_tab=None,
+    struct_sym_tab=None,
+    map_sym_tab=None,
+):
+    if len(call.args) not in (1, 2):
+        raise ValueError(
+            f"get_stack expects atmost two arguments (buf, flags), got {len(call.args)}"
+        )
+    ctx_ptr = func.args[0]  # First argument to the function is ctx
+    buf_arg = call.args[0]
+    flags_arg = call.args[1] if len(call.args) == 2 else None
+    buf_ptr, buf_size = get_buffer_ptr_and_size(
+        buf_arg, builder, local_sym_tab, struct_sym_tab
+    )
+    flags_val = get_flags_val(flags_arg, builder, local_sym_tab)
+    if isinstance(flags_val, int):
+        flags_val = ir.Constant(ir.IntType(64), flags_val)
+
+    buf_void_ptr = builder.bitcast(buf_ptr, ir.PointerType())
+    fn_type = ir.FunctionType(
+        ir.IntType(64),
+        [
+            ir.PointerType(ir.IntType(8)),
+            ir.PointerType(),
+            ir.IntType(64),
+            ir.IntType(64),
+        ],
+        var_arg=False,
+    )
+    fn_ptr_type = ir.PointerType(fn_type)
+    fn_addr = ir.Constant(ir.IntType(64), BPFHelperID.BPF_GET_STACK.value)
+    fn_ptr = builder.inttoptr(fn_addr, fn_ptr_type)
+    result = builder.call(
+        fn_ptr,
+        [ctx_ptr, buf_void_ptr, ir.Constant(ir.IntType(64), buf_size), flags_val],
+        tail=False,
+    )
+    return result, ir.IntType(64)
+
+
 def handle_helper_call(
     call,
     module,

pythonbpf/helper/helpers.py

@@ -52,6 +52,11 @@ def skb_store_bytes(offset, from_buf, size, flags=0):
     return ctypes.c_int64(0)
 
 
+def get_stack(buf, flags=0):
+    """get the current stack trace"""
+    return ctypes.c_int64(0)
+
+
 XDP_ABORTED = ctypes.c_int64(0)
 XDP_DROP = ctypes.c_int64(1)
 XDP_PASS = ctypes.c_int64(2)