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Refactor bpf_perf_event_output_emitter

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Pragyansh Chaturvedi
2025-10-01 22:49:50 +05:30
parent 6ccbab402f
commit 4f33db206c
2 changed files with 49 additions and 50 deletions
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63
pythonbpf/helper/bpf_helper_handler.py
View File

@ -2,7 +2,7 @@ import ast
from llvmlite import ir from llvmlite import ir
from pythonbpf.expr_pass import eval_expr from pythonbpf.expr_pass import eval_expr
from enum import Enum from enum import Enum
from .helper_utils import HelperHandlerRegistry, get_or_create_ptr_from_arg, get_flags_val, _handle_fstring_print, _simple_string_print from .helper_utils import HelperHandlerRegistry, get_or_create_ptr_from_arg, get_flags_val, _handle_fstring_print, _simple_string_print, _get_data_ptr_and_size
class BPFHelperID(Enum): class BPFHelperID(Enum):
@ -201,50 +201,31 @@ def bpf_perf_event_output_handler(call, map_ptr, module, builder, func,
data_arg = call.args[0] data_arg = call.args[0]
ctx_ptr = func.args[0] # First argument to the function is ctx ctx_ptr = func.args[0] # First argument to the function is ctx
if isinstance(data_arg, ast.Name): data_ptr, size_val = _get_data_ptr_and_size(data_arg, local_sym_tab,
data_name = data_arg.id struct_sym_tab,
if local_sym_tab and data_name in local_sym_tab: local_var_metadata)
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 # BPF_F_CURRENT_CPU is -1 in 32 bit
flags_val = ir.Constant(ir.IntType(64), 0xFFFFFFFF) flags_val = ir.Constant(ir.IntType(64), 0xFFFFFFFF)
map_void_ptr = builder.bitcast(map_ptr, ir.PointerType()) map_void_ptr = builder.bitcast(map_ptr, ir.PointerType())
data_void_ptr = builder.bitcast(data_ptr, ir.PointerType()) data_void_ptr = builder.bitcast(data_ptr, ir.PointerType())
fn_type = ir.FunctionType( fn_type = ir.FunctionType(
ir.IntType(64), ir.IntType(64),
[ir.PointerType(ir.IntType(8)), ir.PointerType(), ir.IntType(64), [ir.PointerType(ir.IntType(8)), ir.PointerType(), ir.IntType(64),
ir.PointerType(), ir.IntType(64)], ir.PointerType(), ir.IntType(64)],
var_arg=False var_arg=False
) )
fn_ptr_type = ir.PointerType(fn_type) fn_ptr_type = ir.PointerType(fn_type)
# helper id # helper id
fn_addr = ir.Constant(ir.IntType( fn_addr = ir.Constant(ir.IntType(64),
64), BPFHelperID.BPF_PERF_EVENT_OUTPUT.value) BPFHelperID.BPF_PERF_EVENT_OUTPUT.value)
fn_ptr = builder.inttoptr(fn_addr, fn_ptr_type) fn_ptr = builder.inttoptr(fn_addr, fn_ptr_type)
result = builder.call( result = builder.call(
fn_ptr, [ctx_ptr, map_void_ptr, flags_val, data_void_ptr, size_val], tail=False) fn_ptr, [ctx_ptr, map_void_ptr, flags_val, data_void_ptr, size_val], tail=False)
return result, None return result, None
else:
raise NotImplementedError(
"Only simple object names are supported as data in perf event output.")
def handle_helper_call(call, module, builder, func, def handle_helper_call(call, module, builder, func,

36
pythonbpf/helper/helper_utils.py
View File

@ -168,7 +168,7 @@ def _process_attr_in_fval(attr_node, fmt_parts, exprs,
raise ValueError( raise ValueError(
f"Variable metadata for '{var_name}' not found in local variable metadata") f"Variable metadata for '{var_name}' not found in local variable metadata")
var_type = local_sym_tab[var_name][1] var_type = local_var_metadata[var_name]
if var_type not in struct_sym_tab: if var_type not in struct_sym_tab:
raise ValueError( raise ValueError(
f"Struct type '{var_type}' for variable '{var_name}' not found in struct symbol table") f"Struct type '{var_type}' for variable '{var_name}' not found in struct symbol table")
@ -251,12 +251,30 @@ def _prepare_expr_args(expr, func, module, builder,
return ir.Constant(ir.IntType(64), 0) return ir.Constant(ir.IntType(64), 0)
def _call_bpf_printk_helper(args, builder): def _get_data_ptr_and_size(data_arg, local_sym_tab, struct_sym_tab,
"""Call the BPF_PRINTK helper function with the provided arguments.""" local_var_metadata):
fn_type = ir.FunctionType( """Extract data pointer and size information for perf event output."""
ir.IntType(64), [ir.PointerType(), ir.IntType(32)], var_arg=True) if isinstance(data_arg, ast.Name):
fn_ptr_type = ir.PointerType(fn_type) data_name = data_arg.id
fn_addr = ir.Constant(ir.IntType(64), BPFHelperID.BPF_PRINTK.value) if local_sym_tab and data_name in local_sym_tab:
fn_ptr = builder.inttoptr(fn_addr, fn_ptr_type) data_ptr = local_sym_tab[data_name][0]
else:
raise ValueError(
f"Data variable {data_name} not found in local symbol table.")
return builder.call(fn_ptr, args, tail=True) # Check if 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)
return data_ptr, size_val
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.")
else:
raise NotImplementedError(
"Only simple object names are supported as data in perf event output.")