Implement bpf_probe_read_kernel_str helper, Allow i8* to i8 ArrayType conversion

pythonbpf/helper/bpf_helper_handler.py

@@ -8,6 +8,8 @@ from .helper_utils import (
     get_flags_val,
     get_data_ptr_and_size,
     get_buffer_ptr_and_size,
+    get_char_array_ptr_and_size,
+    get_ptr_from_arg,
 )
 from .printk_formatter import simple_string_print, handle_fstring_print
 
@@ -26,6 +28,7 @@ class BPFHelperID(Enum):
     BPF_GET_CURRENT_PID_TGID = 14
     BPF_GET_CURRENT_COMM = 16
     BPF_PERF_EVENT_OUTPUT = 25
+    BPF_PROBE_READ_KERNEL_STR = 115
 
 
 @HelperHandlerRegistry.register("ktime")
@@ -368,6 +371,68 @@ def bpf_perf_event_output_handler(
     return result, None
 
 
+def emit_probe_read_kernel_str_call(builder, dst_ptr, dst_size, src_ptr):
+    """Emit LLVM IR call to bpf_probe_read_kernel_str"""
+
+    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_STR.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_str (size={dst_size})")
+    return result
+
+
+@HelperHandlerRegistry.register("probe_read_str")
+def bpf_probe_read_kernel_str_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_str helper."""
+
+    if len(call.args) != 2:
+        raise ValueError(
+            f"probe_read_str expects 2 args (dst, src), got {len(call.args)}"
+        )
+
+    # Get destination buffer (char array -> i8*)
+    dst_ptr, dst_size = get_char_array_ptr_and_size(
+        call.args[0], builder, local_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_str_call(builder, dst_ptr, dst_size, src_ptr)
+
+    logger.info(f"Emitted bpf_probe_read_kernel_str (size={dst_size})")
+    return result, ir.IntType(64)
+
+
 def handle_helper_call(
     call,
     module,