Fix imports and type issues for bpf_probe_read

Author: r41k0u

pythonbpf/helper/__init__.py

@@ -1,7 +1,17 @@
 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 .helpers import ktime, pid, deref, comm, probe_read_str, random, XDP_DROP, XDP_PASS
+from .helpers import (
+    ktime,
+    pid,
+    deref,
+    comm,
+    probe_read_str,
+    random,
+    probe_read,
+    XDP_DROP,
+    XDP_PASS,
+)
 
 
 # Register the helper handler with expr module
@@ -66,6 +76,7 @@ def helper_call_handler(
     "comm",
     "probe_read_str",
     "random",
+    "probe_read",
     "XDP_DROP",
     "XDP_PASS",
 ]

pythonbpf/helper/bpf_helper_handler.py

@@ -476,23 +476,20 @@ def bpf_probe_read_emitter(
     if len(call.args) != 3:
         logger.warn("Expected 3 args for probe_read helper")
         return
-    dst_ptr, _ = get_ptr_from_arg(
-        call.args[0], func, module, builder, local_sym_tab, map_sym_tab, struct_sym_tab
+    dst_ptr = get_or_create_ptr_from_arg(
+        func, module, call.args[0], builder, local_sym_tab, map_sym_tab, struct_sym_tab
     )
-    size_val = (
-        get_int_value_from_arg(
-            call.args[1],
-            func,
-            module,
-            builder,
-            local_sym_tab,
-            map_sym_tab,
-            struct_sym_tab,
-        )
-        & 0xFFFFFFFF
+    size_val = get_int_value_from_arg(
+        call.args[1],
+        func,
+        module,
+        builder,
+        local_sym_tab,
+        map_sym_tab,
+        struct_sym_tab,
     )
-    src_ptr, _ = get_ptr_from_arg(
-        call.args[2], func, module, builder, local_sym_tab, map_sym_tab, struct_sym_tab
+    src_ptr = get_or_create_ptr_from_arg(
+        func, module, call.args[2], builder, local_sym_tab, map_sym_tab, struct_sym_tab
     )
     fn_type = ir.FunctionType(
         ir.IntType(64),
@@ -507,7 +504,7 @@ def bpf_probe_read_emitter(
         fn_ptr,
         [
             builder.bitcast(dst_ptr, ir.PointerType()),
-            ir.Constant(ir.IntType(32), size_val),
+            builder.trunc(size_val, ir.IntType(32)),
             builder.bitcast(src_ptr, ir.PointerType()),
         ],
         tail=False,

pythonbpf/helper/helpers.py

@@ -32,6 +32,11 @@ def random():
     return ctypes.c_int32(0)
 
 
+def probe_read(dst, size, src):
+    """Safely read data from kernel memory"""
+    return ctypes.c_int64(0)
+
+
 XDP_ABORTED = ctypes.c_int64(0)
 XDP_DROP = ctypes.c_int64(1)
 XDP_PASS = ctypes.c_int64(2)