mirror of
https://github.com/varun-r-mallya/Python-BPF.git
synced 2025-12-31 21:06:25 +00:00
424 lines
17 KiB
Python
424 lines
17 KiB
Python
import ast
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from llvmlite import ir
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from .expr_pass import eval_expr
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def bpf_ktime_get_ns_emitter(call, map_ptr, module, builder, func, local_sym_tab=None, local_var_metadata=None):
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"""
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Emit LLVM IR for bpf_ktime_get_ns helper function call.
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"""
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# func is an arg to just have a uniform signature with other emitters
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helper_id = ir.Constant(ir.IntType(64), 5)
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fn_type = ir.FunctionType(ir.IntType(64), [], var_arg=False)
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fn_ptr_type = ir.PointerType(fn_type)
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fn_ptr = builder.inttoptr(helper_id, fn_ptr_type)
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result = builder.call(fn_ptr, [], tail=False)
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return result
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def bpf_map_lookup_elem_emitter(call, map_ptr, module, builder, func, local_sym_tab=None, struct_sym_tab=None, local_var_metadata=None):
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"""
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Emit LLVM IR for bpf_map_lookup_elem helper function call.
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"""
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if call.args and len(call.args) != 1:
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raise ValueError("Map lookup expects exactly one argument, got "
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f"{len(call.args)}")
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key_arg = call.args[0]
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if isinstance(key_arg, ast.Name):
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key_name = key_arg.id
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if local_sym_tab and key_name in local_sym_tab:
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key_ptr = local_sym_tab[key_name]
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else:
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raise ValueError(
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f"Key variable {key_name} not found in local symbol table.")
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elif isinstance(key_arg, ast.Constant) and isinstance(key_arg.value, int):
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# handle constant integer keys
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key_val = key_arg.value
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key_type = ir.IntType(64)
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key_ptr = builder.alloca(key_type)
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key_ptr.align = key_type // 8
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builder.store(ir.Constant(key_type, key_val), key_ptr)
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else:
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raise NotImplementedError(
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"Only simple variable names are supported as keys in map lookup.")
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if key_ptr is None:
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raise ValueError("Key pointer is None.")
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map_void_ptr = builder.bitcast(map_ptr, ir.PointerType())
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fn_type = ir.FunctionType(
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ir.PointerType(), # Return type: void*
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[ir.PointerType(), ir.PointerType()], # Args: (void*, void*)
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var_arg=False
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)
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fn_ptr_type = ir.PointerType(fn_type)
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# Helper ID 1 is bpf_map_lookup_elem
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fn_addr = ir.Constant(ir.IntType(64), 1)
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fn_ptr = builder.inttoptr(fn_addr, fn_ptr_type)
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result = builder.call(fn_ptr, [map_void_ptr, key_ptr], tail=False)
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return result
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def bpf_printk_emitter(call, map_ptr, module, builder, func, local_sym_tab=None, local_var_metadata=None):
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if not hasattr(func, "_fmt_counter"):
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func._fmt_counter = 0
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if not call.args:
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raise ValueError("print expects at least one argument")
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if isinstance(call.args[0], ast.JoinedStr):
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fmt_parts = []
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exprs = []
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for value in call.args[0].values:
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if isinstance(value, ast.Constant):
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if isinstance(value.value, str):
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fmt_parts.append(value.value)
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elif isinstance(value.value, int):
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fmt_parts.append("%lld")
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exprs.append(ir.Constant(ir.IntType(64), value.value))
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else:
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raise NotImplementedError(
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"Only string and integer constants are supported in f-string.")
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elif isinstance(value, ast.FormattedValue):
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# Assume int for now
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fmt_parts.append("%lld")
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if isinstance(value.value, ast.Name):
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exprs.append(value.value)
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else:
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raise NotImplementedError(
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"Only simple variable names are supported in formatted values.")
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else:
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raise NotImplementedError(
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"Unsupported value type in f-string.")
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fmt_str = "".join(fmt_parts) + "\n" + "\0"
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fmt_name = f"{func.name}____fmt{func._fmt_counter}"
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func._fmt_counter += 1
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fmt_gvar = ir.GlobalVariable(
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module, ir.ArrayType(ir.IntType(8), len(fmt_str)), name=fmt_name)
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fmt_gvar.global_constant = True
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fmt_gvar.initializer = ir.Constant(
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ir.ArrayType(ir.IntType(8), len(fmt_str)),
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bytearray(fmt_str.encode("utf8"))
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)
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fmt_gvar.linkage = "internal"
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fmt_gvar.align = 1
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fmt_ptr = builder.bitcast(fmt_gvar, ir.PointerType())
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args = [fmt_ptr, ir.Constant(ir.IntType(32), len(fmt_str))]
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# Only 3 args supported in bpf_printk
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if len(exprs) > 3:
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print(
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"Warning: bpf_printk supports up to 3 arguments, extra arguments will be ignored.")
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for expr in exprs[:3]:
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val = eval_expr(func, module, builder, expr, local_sym_tab, None)
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if val:
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if isinstance(val.type, ir.PointerType):
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val = builder.ptrtoint(val, ir.IntType(64))
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elif isinstance(val.type, ir.IntType):
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if val.type.width < 64:
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val = builder.sext(val, ir.IntType(64))
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else:
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print(
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"Warning: Only integer and pointer types are supported in bpf_printk arguments. Others will be converted to 0.")
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val = ir.Constant(ir.IntType(64), 0)
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args.append(val)
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else:
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print(
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"Warning: Failed to evaluate expression for bpf_printk argument. It will be converted to 0.")
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args.append(ir.Constant(ir.IntType(64), 0))
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fn_type = ir.FunctionType(ir.IntType(
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64), [ir.PointerType(), ir.IntType(32)], var_arg=True)
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fn_ptr_type = ir.PointerType(fn_type)
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fn_addr = ir.Constant(ir.IntType(64), 6)
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fn_ptr = builder.inttoptr(fn_addr, fn_ptr_type)
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return builder.call(fn_ptr, args, tail=True)
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for arg in call.args:
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if isinstance(arg, ast.Constant) and isinstance(arg.value, str):
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fmt_str = arg.value + "\n" + "\0"
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fmt_name = f"{func.name}____fmt{func._fmt_counter}"
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func._fmt_counter += 1
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fmt_gvar = ir.GlobalVariable(
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module, ir.ArrayType(ir.IntType(8), len(fmt_str)), name=fmt_name)
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fmt_gvar.global_constant = True
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fmt_gvar.initializer = ir.Constant( # type: ignore
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ir.ArrayType(ir.IntType(8), len(fmt_str)),
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bytearray(fmt_str.encode("utf8"))
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)
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fmt_gvar.linkage = "internal"
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fmt_gvar.align = 1 # type: ignore
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fmt_ptr = builder.bitcast(fmt_gvar, ir.PointerType())
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fn_type = ir.FunctionType(ir.IntType(
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64), [ir.PointerType(), ir.IntType(32)], var_arg=True)
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fn_ptr_type = ir.PointerType(fn_type)
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fn_addr = ir.Constant(ir.IntType(64), 6)
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fn_ptr = builder.inttoptr(fn_addr, fn_ptr_type)
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builder.call(fn_ptr, [fmt_ptr, ir.Constant(
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ir.IntType(32), len(fmt_str))], tail=True)
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def bpf_map_update_elem_emitter(call, map_ptr, module, builder, func, local_sym_tab=None, struct_sym_tab=None, local_var_metadata=None):
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"""
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Emit LLVM IR for bpf_map_update_elem helper function call.
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Expected call signature: map.update(key, value, flags=0)
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"""
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if not call.args or len(call.args) < 2 or len(call.args) > 3:
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raise ValueError("Map update expects 2 or 3 arguments (key, value, flags), got "
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f"{len(call.args)}")
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key_arg = call.args[0]
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value_arg = call.args[1]
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flags_arg = call.args[2] if len(call.args) > 2 else None
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# Handle key
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if isinstance(key_arg, ast.Name):
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key_name = key_arg.id
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if local_sym_tab and key_name in local_sym_tab:
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key_ptr = local_sym_tab[key_name]
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else:
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raise ValueError(
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f"Key variable {key_name} not found in local symbol table.")
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elif isinstance(key_arg, ast.Constant) and isinstance(key_arg.value, int):
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# Handle constant integer keys
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key_val = key_arg.value
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key_type = ir.IntType(64)
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key_ptr = builder.alloca(key_type)
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key_ptr.align = key_type.width // 8
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builder.store(ir.Constant(key_type, key_val), key_ptr)
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else:
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raise NotImplementedError(
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"Only simple variable names and integer constants are supported as keys in map update.")
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# Handle value
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if isinstance(value_arg, ast.Name):
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value_name = value_arg.id
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if local_sym_tab and value_name in local_sym_tab:
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value_ptr = local_sym_tab[value_name]
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else:
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raise ValueError(
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f"Value variable {value_name} not found in local symbol table.")
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elif isinstance(value_arg, ast.Constant) and isinstance(value_arg.value, int):
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# Handle constant integers
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value_val = value_arg.value
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value_type = ir.IntType(64)
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value_ptr = builder.alloca(value_type)
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value_ptr.align = value_type.width // 8
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builder.store(ir.Constant(value_type, value_val), value_ptr)
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else:
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raise NotImplementedError(
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"Only simple variable names and integer constants are supported as values in map update.")
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# Handle flags argument (defaults to 0)
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if flags_arg is not None:
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if isinstance(flags_arg, ast.Constant) and isinstance(flags_arg.value, int):
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flags_val = flags_arg.value
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elif isinstance(flags_arg, ast.Name):
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flags_name = flags_arg.id
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if local_sym_tab and flags_name in local_sym_tab:
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# Assume it's a stored integer value, load it
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flags_ptr = local_sym_tab[flags_name]
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flags_val = builder.load(flags_ptr)
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else:
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raise ValueError(
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f"Flags variable {flags_name} not found in local symbol table.")
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else:
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raise NotImplementedError(
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"Only integer constants and simple variable names are supported as flags in map update.")
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else:
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flags_val = 0
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if key_ptr is None or value_ptr is None:
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raise ValueError("Key pointer or value pointer is None.")
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map_void_ptr = builder.bitcast(map_ptr, ir.PointerType())
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fn_type = ir.FunctionType(
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ir.IntType(64),
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[ir.PointerType(), ir.PointerType(), ir.PointerType(), ir.IntType(64)],
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var_arg=False
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)
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fn_ptr_type = ir.PointerType(fn_type)
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# helper id
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fn_addr = ir.Constant(ir.IntType(64), 2)
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fn_ptr = builder.inttoptr(fn_addr, fn_ptr_type)
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if isinstance(flags_val, int):
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flags_const = ir.Constant(ir.IntType(64), flags_val)
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else:
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flags_const = flags_val
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result = builder.call(
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fn_ptr, [map_void_ptr, key_ptr, value_ptr, flags_const], tail=False)
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return result
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def bpf_map_delete_elem_emitter(call, map_ptr, module, builder, func, local_sym_tab=None, struct_sym_tab=None, local_var_metadata=None):
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"""
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Emit LLVM IR for bpf_map_delete_elem helper function call.
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Expected call signature: map.delete(key)
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"""
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# Check for correct number of arguments
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if not call.args or len(call.args) != 1:
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raise ValueError("Map delete expects exactly 1 argument (key), got "
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f"{len(call.args)}")
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key_arg = call.args[0]
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# Handle key argument
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if isinstance(key_arg, ast.Name):
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key_name = key_arg.id
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if local_sym_tab and key_name in local_sym_tab:
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key_ptr = local_sym_tab[key_name]
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else:
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raise ValueError(
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f"Key variable {key_name} not found in local symbol table.")
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elif isinstance(key_arg, ast.Constant) and isinstance(key_arg.value, int):
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# Handle constant integer keys
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key_val = key_arg.value
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key_type = ir.IntType(64)
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key_ptr = builder.alloca(key_type)
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key_ptr.align = key_type.width // 8
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builder.store(ir.Constant(key_type, key_val), key_ptr)
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else:
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raise NotImplementedError(
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"Only simple variable names and integer constants are supported as keys in map delete.")
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if key_ptr is None:
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raise ValueError("Key pointer is None.")
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# Cast map pointer to void*
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map_void_ptr = builder.bitcast(map_ptr, ir.PointerType())
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# Define function type for bpf_map_delete_elem
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fn_type = ir.FunctionType(
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ir.IntType(64), # Return type: int64 (status code)
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[ir.PointerType(), ir.PointerType()], # Args: (void*, void*)
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var_arg=False
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)
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fn_ptr_type = ir.PointerType(fn_type)
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# Helper ID 3 is bpf_map_delete_elem
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fn_addr = ir.Constant(ir.IntType(64), 3)
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fn_ptr = builder.inttoptr(fn_addr, fn_ptr_type)
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# Call the helper function
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result = builder.call(fn_ptr, [map_void_ptr, key_ptr], tail=False)
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return result
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def bpf_get_current_pid_tgid_emitter(call, map_ptr, module, builder, func, local_sym_tab=None, local_var_metadata=None):
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"""
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Emit LLVM IR for bpf_get_current_pid_tgid helper function call.
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"""
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# func is an arg to just have a uniform signature with other emitters
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helper_id = ir.Constant(ir.IntType(64), 14)
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fn_type = ir.FunctionType(ir.IntType(64), [], var_arg=False)
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fn_ptr_type = ir.PointerType(fn_type)
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fn_ptr = builder.inttoptr(helper_id, fn_ptr_type)
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result = builder.call(fn_ptr, [], tail=False)
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# Extract the lower 32 bits (PID) using bitwise AND with 0xFFFFFFFF
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mask = ir.Constant(ir.IntType(64), 0xFFFFFFFF)
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pid = builder.and_(result, mask)
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return pid
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def bpf_perf_event_output_handler(call, map_ptr, module, builder, func, local_sym_tab=None, struct_sym_tab=None, local_var_metadata=None):
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if len(call.args) != 1:
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raise ValueError("Perf event output expects exactly one argument (data), got "
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f"{len(call.args)}")
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data_arg = call.args[0]
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ctx_ptr = func.args[0] # First argument to the function is ctx
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if isinstance(data_arg, ast.Name):
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data_name = data_arg.id
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if local_sym_tab and data_name in local_sym_tab:
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data_ptr = local_sym_tab[data_name]
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else:
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raise ValueError(
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f"Data variable {data_name} not found in local symbol table.")
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# Check is data_name is a struct
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if local_var_metadata and data_name in local_var_metadata:
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data_type = local_var_metadata[data_name]
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if data_type in struct_sym_tab:
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struct_info = struct_sym_tab[data_type]
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data_size = 0
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for field_type in struct_info["type"].elements:
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if isinstance(field_type, ir.IntType):
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data_size += field_type.width // 8
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elif isinstance(field_type, ir.PointerType):
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data_size += 8
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helper_func_list = {
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"lookup": bpf_map_lookup_elem_emitter,
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"print": bpf_printk_emitter,
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"ktime": bpf_ktime_get_ns_emitter,
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"update": bpf_map_update_elem_emitter,
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"delete": bpf_map_delete_elem_emitter,
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"pid": bpf_get_current_pid_tgid_emitter,
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"output": bpf_perf_event_output_handler,
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}
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def handle_helper_call(call, module, builder, func, local_sym_tab=None, map_sym_tab=None, struct_sym_tab=None, local_var_metadata=None):
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if isinstance(call.func, ast.Name):
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func_name = call.func.id
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if func_name in helper_func_list:
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# it is not a map method call
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return helper_func_list[func_name](call, None, module, builder, func, local_sym_tab)
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else:
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raise NotImplementedError(
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f"Function {func_name} is not implemented as a helper function.")
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elif isinstance(call.func, ast.Attribute):
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# likely a map method call
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if isinstance(call.func.value, ast.Call) and isinstance(call.func.value.func, ast.Name):
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map_name = call.func.value.func.id
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method_name = call.func.attr
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if map_sym_tab and map_name in map_sym_tab:
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map_ptr = map_sym_tab[map_name]
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if method_name in helper_func_list:
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print(local_var_metadata)
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return helper_func_list[method_name](
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call, map_ptr, module, builder, func, local_sym_tab, struct_sym_tab, local_var_metadata)
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else:
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raise NotImplementedError(
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f"Map method {method_name} is not implemented as a helper function.")
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else:
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raise ValueError(
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f"Map variable {map_name} not found in symbol tables.")
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elif isinstance(call.func.value, ast.Name):
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obj_name = call.func.value.id
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method_name = call.func.attr
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if map_sym_tab and obj_name in map_sym_tab:
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map_ptr = map_sym_tab[obj_name]
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if method_name in helper_func_list:
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return helper_func_list[method_name](
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call, map_ptr, module, builder, func, local_sym_tab, struct_sym_tab, local_var_metadata)
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else:
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raise NotImplementedError(
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f"Map method {method_name} is not implemented as a helper function.")
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else:
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raise ValueError(
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f"Map variable {obj_name} not found in symbol tables.")
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else:
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raise NotImplementedError(
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"Attribute not supported for map method calls.")
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