Files
python-bpf/pythonbpf/bpf_helper_handler.py

655 lines
23 KiB
Python

import ast
from llvmlite import ir
from .expr_pass import eval_expr
def bpf_ktime_get_ns_emitter(
call,
map_ptr,
module,
builder,
func,
local_sym_tab=None,
struct_sym_tab=None,
local_var_metadata=None,
):
"""
Emit LLVM IR for bpf_ktime_get_ns helper function call.
"""
# func is an arg to just have a uniform signature with other emitters
helper_id = ir.Constant(ir.IntType(64), 5)
fn_type = ir.FunctionType(ir.IntType(64), [], var_arg=False)
fn_ptr_type = ir.PointerType(fn_type)
fn_ptr = builder.inttoptr(helper_id, fn_ptr_type)
result = builder.call(fn_ptr, [], tail=False)
return result, ir.IntType(64)
def bpf_map_lookup_elem_emitter(
call,
map_ptr,
module,
builder,
func,
local_sym_tab=None,
struct_sym_tab=None,
local_var_metadata=None,
):
"""
Emit LLVM IR for bpf_map_lookup_elem helper function call.
"""
if call.args and len(call.args) != 1:
raise ValueError(
"Map lookup expects exactly one argument, got " f"{len(call.args)}"
)
key_arg = call.args[0]
if isinstance(key_arg, ast.Name):
key_name = key_arg.id
if local_sym_tab and key_name in local_sym_tab:
key_ptr = local_sym_tab[key_name][0]
else:
raise ValueError(
f"Key variable {key_name} not found in local symbol table."
)
elif isinstance(key_arg, ast.Constant) and isinstance(key_arg.value, int):
# handle constant integer keys
key_val = key_arg.value
key_type = ir.IntType(64)
key_ptr = builder.alloca(key_type)
key_ptr.align = key_type // 8
builder.store(ir.Constant(key_type, key_val), key_ptr)
else:
raise NotImplementedError(
"Only simple variable names are supported as keys in map lookup."
)
if key_ptr is None:
raise ValueError("Key pointer is None.")
map_void_ptr = builder.bitcast(map_ptr, ir.PointerType())
fn_type = ir.FunctionType(
ir.PointerType(), # Return type: void*
[ir.PointerType(), ir.PointerType()], # Args: (void*, void*)
var_arg=False,
)
fn_ptr_type = ir.PointerType(fn_type)
# Helper ID 1 is bpf_map_lookup_elem
fn_addr = ir.Constant(ir.IntType(64), 1)
fn_ptr = builder.inttoptr(fn_addr, fn_ptr_type)
result = builder.call(fn_ptr, [map_void_ptr, key_ptr], tail=False)
return result, ir.PointerType()
def bpf_printk_emitter(
call,
map_ptr,
module,
builder,
func,
local_sym_tab=None,
struct_sym_tab=None,
local_var_metadata=None,
):
if not hasattr(func, "_fmt_counter"):
func._fmt_counter = 0
if not call.args:
raise ValueError("print expects at least one argument")
if isinstance(call.args[0], ast.JoinedStr):
fmt_parts = []
exprs = []
for value in call.args[0].values:
print("Value in f-string:", ast.dump(value))
if isinstance(value, ast.Constant):
if isinstance(value.value, str):
fmt_parts.append(value.value)
elif isinstance(value.value, int):
fmt_parts.append("%lld")
exprs.append(ir.Constant(ir.IntType(64), value.value))
else:
raise NotImplementedError(
"Only string and integer constants are supported in f-string."
)
elif isinstance(value, ast.FormattedValue):
print("Formatted value:", ast.dump(value))
# TODO: Dirty handling here, only checks for int or str
if isinstance(value.value, ast.Name):
if local_sym_tab and value.value.id in local_sym_tab:
var_ptr, var_type = local_sym_tab[value.value.id]
if isinstance(var_type, ir.IntType):
fmt_parts.append("%lld")
exprs.append(value.value)
elif var_type == ir.PointerType(ir.IntType(8)):
# Case with string
fmt_parts.append("%s")
exprs.append(value.value)
else:
raise NotImplementedError(
"Only integer and pointer types are supported in formatted values."
)
else:
raise ValueError(
f"Variable {value.value.id} not found in local symbol table."
)
elif isinstance(value.value, ast.Attribute):
# object field access from struct
if (
isinstance(value.value.value, ast.Name)
and local_sym_tab
and value.value.value.id in local_sym_tab
):
var_name = value.value.value.id
field_name = value.value.attr
if local_var_metadata and var_name in local_var_metadata:
var_type = local_var_metadata[var_name]
if var_type in struct_sym_tab:
struct_info = struct_sym_tab[var_type]
if field_name in struct_info.fields:
field_type = struct_info.field_type(field_name)
if isinstance(field_type, ir.IntType):
fmt_parts.append("%lld")
exprs.append(value.value)
elif field_type == ir.PointerType(ir.IntType(8)):
fmt_parts.append("%s")
exprs.append(value.value)
else:
raise NotImplementedError(
"Only integer and pointer types are supported in formatted values."
)
else:
raise ValueError(
f"Field {field_name} not found in struct {var_type}."
)
else:
raise ValueError(
f"Struct type {var_type} for variable {var_name} not found in struct symbol table."
)
else:
raise ValueError(
f"Metadata for variable {var_name} not found in local variable metadata."
)
else:
raise ValueError(
f"Variable {value.value.value.id} not found in local symbol table."
)
else:
raise NotImplementedError(
"Only simple variable names are supported in formatted values."
)
else:
raise NotImplementedError("Unsupported value type in f-string.")
fmt_str = "".join(fmt_parts) + "\n" + "\0"
fmt_name = f"{func.name}____fmt{func._fmt_counter}"
func._fmt_counter += 1
fmt_gvar = ir.GlobalVariable(
module, ir.ArrayType(ir.IntType(8), len(fmt_str)), name=fmt_name
)
fmt_gvar.global_constant = True
fmt_gvar.initializer = ir.Constant( # type: ignore
ir.ArrayType(ir.IntType(8), len(fmt_str)), bytearray(fmt_str.encode("utf8"))
)
fmt_gvar.linkage = "internal"
fmt_gvar.align = 1 # type: ignore
fmt_ptr = builder.bitcast(fmt_gvar, ir.PointerType())
args = [fmt_ptr, ir.Constant(ir.IntType(32), len(fmt_str))]
# Only 3 args supported in bpf_printk
if len(exprs) > 3:
print(
"Warning: bpf_printk supports up to 3 arguments, extra arguments will be ignored."
)
for expr in exprs[:3]:
print(f"{ast.dump(expr)}")
val, _ = eval_expr(
func,
module,
builder,
expr,
local_sym_tab,
None,
struct_sym_tab,
local_var_metadata,
)
if val:
if isinstance(val.type, ir.PointerType):
val = builder.ptrtoint(val, ir.IntType(64))
elif isinstance(val.type, ir.IntType):
if val.type.width < 64:
val = builder.sext(val, ir.IntType(64))
else:
print(
"Warning: Only integer and pointer types are supported in bpf_printk arguments. Others will be converted to 0."
)
val = ir.Constant(ir.IntType(64), 0)
args.append(val)
else:
print(
"Warning: Failed to evaluate expression for bpf_printk argument. It will be converted to 0."
)
args.append(ir.Constant(ir.IntType(64), 0))
fn_type = ir.FunctionType(
ir.IntType(64), [ir.PointerType(), ir.IntType(32)], var_arg=True
)
fn_ptr_type = ir.PointerType(fn_type)
fn_addr = ir.Constant(ir.IntType(64), 6)
fn_ptr = builder.inttoptr(fn_addr, fn_ptr_type)
return builder.call(fn_ptr, args, tail=True)
for arg in call.args:
if isinstance(arg, ast.Constant) and isinstance(arg.value, str):
fmt_str = arg.value + "\n" + "\0"
fmt_name = f"{func.name}____fmt{func._fmt_counter}"
func._fmt_counter += 1
fmt_gvar = ir.GlobalVariable(
module, ir.ArrayType(ir.IntType(8), len(fmt_str)), name=fmt_name
)
fmt_gvar.global_constant = True
fmt_gvar.initializer = ir.Constant( # type: ignore
ir.ArrayType(ir.IntType(8), len(fmt_str)),
bytearray(fmt_str.encode("utf8")),
)
fmt_gvar.linkage = "internal"
fmt_gvar.align = 1 # type: ignore
fmt_ptr = builder.bitcast(fmt_gvar, ir.PointerType())
fn_type = ir.FunctionType(
ir.IntType(64), [ir.PointerType(), ir.IntType(32)], var_arg=True
)
fn_ptr_type = ir.PointerType(fn_type)
fn_addr = ir.Constant(ir.IntType(64), 6)
fn_ptr = builder.inttoptr(fn_addr, fn_ptr_type)
builder.call(
fn_ptr, [fmt_ptr, ir.Constant(ir.IntType(32), len(fmt_str))], tail=True
)
return None
def bpf_map_update_elem_emitter(
call,
map_ptr,
module,
builder,
func,
local_sym_tab=None,
struct_sym_tab=None,
local_var_metadata=None,
):
"""
Emit LLVM IR for bpf_map_update_elem helper function call.
Expected call signature: map.update(key, value, flags=0)
"""
if not call.args or len(call.args) < 2 or len(call.args) > 3:
raise ValueError(
"Map update expects 2 or 3 arguments (key, value, flags), got "
f"{len(call.args)}"
)
key_arg = call.args[0]
value_arg = call.args[1]
flags_arg = call.args[2] if len(call.args) > 2 else None
# Handle key
if isinstance(key_arg, ast.Name):
key_name = key_arg.id
if local_sym_tab and key_name in local_sym_tab:
key_ptr = local_sym_tab[key_name][0]
else:
raise ValueError(
f"Key variable {key_name} not found in local symbol table."
)
elif isinstance(key_arg, ast.Constant) and isinstance(key_arg.value, int):
# Handle constant integer keys
key_val = key_arg.value
key_type = ir.IntType(64)
key_ptr = builder.alloca(key_type)
key_ptr.align = key_type.width // 8
builder.store(ir.Constant(key_type, key_val), key_ptr)
else:
raise NotImplementedError(
"Only simple variable names and integer constants are supported as keys in map update."
)
# Handle value
if isinstance(value_arg, ast.Name):
value_name = value_arg.id
if local_sym_tab and value_name in local_sym_tab:
value_ptr = local_sym_tab[value_name][0]
else:
raise ValueError(
f"Value variable {value_name} not found in local symbol table."
)
elif isinstance(value_arg, ast.Constant) and isinstance(value_arg.value, int):
# Handle constant integers
value_val = value_arg.value
value_type = ir.IntType(64)
value_ptr = builder.alloca(value_type)
value_ptr.align = value_type.width // 8
builder.store(ir.Constant(value_type, value_val), value_ptr)
else:
raise NotImplementedError(
"Only simple variable names and integer constants are supported as values in map update."
)
# Handle flags argument (defaults to 0)
if flags_arg is not None:
if isinstance(flags_arg, ast.Constant) and isinstance(flags_arg.value, int):
flags_val = flags_arg.value
elif isinstance(flags_arg, ast.Name):
flags_name = flags_arg.id
if local_sym_tab and flags_name in local_sym_tab:
# Assume it's a stored integer value, load it
flags_ptr = local_sym_tab[flags_name][0]
flags_val = builder.load(flags_ptr)
else:
raise ValueError(
f"Flags variable {flags_name} not found in local symbol table."
)
else:
raise NotImplementedError(
"Only integer constants and simple variable names are supported as flags in map update."
)
else:
flags_val = 0
if key_ptr is None or value_ptr is None:
raise ValueError("Key pointer or value pointer is None.")
map_void_ptr = builder.bitcast(map_ptr, ir.PointerType())
fn_type = ir.FunctionType(
ir.IntType(64),
[ir.PointerType(), ir.PointerType(), ir.PointerType(), ir.IntType(64)],
var_arg=False,
)
fn_ptr_type = ir.PointerType(fn_type)
# helper id
fn_addr = ir.Constant(ir.IntType(64), 2)
fn_ptr = builder.inttoptr(fn_addr, fn_ptr_type)
if isinstance(flags_val, int):
flags_const = ir.Constant(ir.IntType(64), flags_val)
else:
flags_const = flags_val
result = builder.call(
fn_ptr, [map_void_ptr, key_ptr, value_ptr, flags_const], tail=False
)
return result, None
def bpf_map_delete_elem_emitter(
call,
map_ptr,
module,
builder,
func,
local_sym_tab=None,
struct_sym_tab=None,
local_var_metadata=None,
):
"""
Emit LLVM IR for bpf_map_delete_elem helper function call.
Expected call signature: map.delete(key)
"""
# Check for correct number of arguments
if not call.args or len(call.args) != 1:
raise ValueError(
"Map delete expects exactly 1 argument (key), got " f"{len(call.args)}"
)
key_arg = call.args[0]
# Handle key argument
if isinstance(key_arg, ast.Name):
key_name = key_arg.id
if local_sym_tab and key_name in local_sym_tab:
key_ptr = local_sym_tab[key_name][0]
else:
raise ValueError(
f"Key variable {key_name} not found in local symbol table."
)
elif isinstance(key_arg, ast.Constant) and isinstance(key_arg.value, int):
# Handle constant integer keys
key_val = key_arg.value
key_type = ir.IntType(64)
key_ptr = builder.alloca(key_type)
key_ptr.align = key_type.width // 8
builder.store(ir.Constant(key_type, key_val), key_ptr)
else:
raise NotImplementedError(
"Only simple variable names and integer constants are supported as keys in map delete."
)
if key_ptr is None:
raise ValueError("Key pointer is None.")
# Cast map pointer to void*
map_void_ptr = builder.bitcast(map_ptr, ir.PointerType())
# Define function type for bpf_map_delete_elem
fn_type = ir.FunctionType(
ir.IntType(64), # Return type: int64 (status code)
[ir.PointerType(), ir.PointerType()], # Args: (void*, void*)
var_arg=False,
)
fn_ptr_type = ir.PointerType(fn_type)
# Helper ID 3 is bpf_map_delete_elem
fn_addr = ir.Constant(ir.IntType(64), 3)
fn_ptr = builder.inttoptr(fn_addr, fn_ptr_type)
# Call the helper function
result = builder.call(fn_ptr, [map_void_ptr, key_ptr], tail=False)
return result, None
def bpf_get_current_pid_tgid_emitter(
call,
map_ptr,
module,
builder,
func,
local_sym_tab=None,
struct_sym_tab=None,
local_var_metadata=None,
):
"""
Emit LLVM IR for bpf_get_current_pid_tgid helper function call.
"""
# func is an arg to just have a uniform signature with other emitters
helper_id = ir.Constant(ir.IntType(64), 14)
fn_type = ir.FunctionType(ir.IntType(64), [], var_arg=False)
fn_ptr_type = ir.PointerType(fn_type)
fn_ptr = builder.inttoptr(helper_id, fn_ptr_type)
result = builder.call(fn_ptr, [], tail=False)
# Extract the lower 32 bits (PID) using bitwise AND with 0xFFFFFFFF
mask = ir.Constant(ir.IntType(64), 0xFFFFFFFF)
pid = builder.and_(result, mask)
return pid, ir.IntType(64)
def bpf_perf_event_output_handler(
call,
map_ptr,
module,
builder,
func,
local_sym_tab=None,
struct_sym_tab=None,
local_var_metadata=None,
):
if len(call.args) != 1:
raise ValueError(
"Perf event output expects exactly one argument (data), got "
f"{len(call.args)}"
)
data_arg = call.args[0]
ctx_ptr = func.args[0] # First argument to the function is ctx
if isinstance(data_arg, ast.Name):
data_name = data_arg.id
if local_sym_tab and data_name in local_sym_tab:
data_ptr = local_sym_tab[data_name][0]
else:
raise ValueError(
f"Data variable {data_name} not found in local symbol table."
)
# Check is data_name is a struct
if local_var_metadata and data_name in local_var_metadata:
data_type = local_var_metadata[data_name]
if data_type in struct_sym_tab:
struct_info = struct_sym_tab[data_type]
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 -1 in 32 bit
flags_val = ir.Constant(ir.IntType(64), 0xFFFFFFFF)
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, None
else:
raise NotImplementedError(
"Only simple object names are supported as data in perf event output."
)
helper_func_list = {
"lookup": bpf_map_lookup_elem_emitter,
"print": bpf_printk_emitter,
"ktime": bpf_ktime_get_ns_emitter,
"update": bpf_map_update_elem_emitter,
"delete": bpf_map_delete_elem_emitter,
"pid": bpf_get_current_pid_tgid_emitter,
"output": bpf_perf_event_output_handler,
}
def handle_helper_call(
call,
module,
builder,
func,
local_sym_tab=None,
map_sym_tab=None,
struct_sym_tab=None,
local_var_metadata=None,
):
print(local_var_metadata)
if isinstance(call.func, ast.Name):
func_name = call.func.id
if func_name in helper_func_list:
# it is not a map method call
return helper_func_list[func_name](
call,
None,
module,
builder,
func,
local_sym_tab,
struct_sym_tab,
local_var_metadata,
)
else:
raise NotImplementedError(
f"Function {func_name} is not implemented as a helper function."
)
elif isinstance(call.func, ast.Attribute):
# likely a map method call
if isinstance(call.func.value, ast.Call) and isinstance(
call.func.value.func, ast.Name
):
map_name = call.func.value.func.id
method_name = call.func.attr
if map_sym_tab and map_name in map_sym_tab:
map_ptr = map_sym_tab[map_name]
if method_name in helper_func_list:
print(local_var_metadata)
return helper_func_list[method_name](
call,
map_ptr,
module,
builder,
func,
local_sym_tab,
struct_sym_tab,
local_var_metadata,
)
else:
raise NotImplementedError(
f"Map method {method_name} is not implemented as a helper function."
)
else:
raise ValueError(f"Map variable {map_name} not found in symbol tables.")
elif isinstance(call.func.value, ast.Name):
obj_name = call.func.value.id
method_name = call.func.attr
if map_sym_tab and obj_name in map_sym_tab:
map_ptr = map_sym_tab[obj_name]
if method_name in helper_func_list:
return helper_func_list[method_name](
call,
map_ptr,
module,
builder,
func,
local_sym_tab,
struct_sym_tab,
local_var_metadata,
)
else:
raise NotImplementedError(
f"Map method {method_name} is not implemented as a helper function."
)
else:
raise ValueError(f"Map variable {obj_name} not found in symbol tables.")
else:
raise NotImplementedError("Attribute not supported for map method calls.")
return None