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Allow access from struct fields

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This commit is contained in:
Pragyansh Chaturvedi
2025-09-26 23:01:14 +05:30
parent 8c2196c05c
commit de5cc438ab
4 changed files with 65 additions and 9 deletions
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6
examples/execve5.py
View File

@ -26,10 +26,10 @@ def hello(ctx: c_void_p) -> c_int32:
ts = ktime()
process_id = pid()
strobj = "hellohellohello"
dataobj.pid = process_id
dataobj.ts = ts
dataobj.pid = pid()
dataobj.ts = ktime()
# dataobj.comm = strobj
print(f"clone called at {ts} by pid {process_id}, comm {strobj}")
print(f"clone called at {dataobj.ts} by pid {dataobj.pid}, comm {strobj}")
events.output(dataobj)
return c_int32(0)

46
pythonbpf/bpf_helper_handler.py
View File

@ -3,7 +3,7 @@ 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, local_var_metadata=None):
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.
"""
@ -63,7 +63,7 @@ def bpf_map_lookup_elem_emitter(call, map_ptr, module, builder, func, local_sym_
return result, ir.PointerType()
def bpf_printk_emitter(call, map_ptr, module, builder, func, local_sym_tab=None, local_var_metadata=None):
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
@ -101,10 +101,42 @@ def bpf_printk_emitter(call, map_ptr, module, builder, func, local_sym_tab=None,
else:
raise NotImplementedError(
"Only integer and pointer types are supported in formatted values.")
print("Formatted value variable:", var_ptr, var_type)
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_index = struct_info["fields"][field_name]
field_type = struct_info["field_types"][field_index]
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.")
@ -136,8 +168,9 @@ def bpf_printk_emitter(call, map_ptr, module, builder, func, local_sym_tab=None,
"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)
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))
@ -339,7 +372,7 @@ def bpf_map_delete_elem_emitter(call, map_ptr, module, builder, func, local_sym_
return result, None
def bpf_get_current_pid_tgid_emitter(call, map_ptr, module, builder, func, local_sym_tab=None, local_var_metadata=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.
"""
@ -420,11 +453,12 @@ helper_func_list = {
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)
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.")

21
pythonbpf/expr_pass.py
View File

@ -4,6 +4,7 @@ from llvmlite import ir
def eval_expr(func, module, builder, expr, local_sym_tab, map_sym_tab, structs_sym_tab=None, local_var_metadata=None):
print(f"Evaluating expression: {ast.dump(expr)}")
print(local_var_metadata)
if isinstance(expr, ast.Name):
if expr.id in local_sym_tab:
var = local_sym_tab[expr.id][0]
@ -66,6 +67,25 @@ def eval_expr(func, module, builder, expr, local_sym_tab, map_sym_tab, structs_s
if method_name in helper_func_list:
return handle_helper_call(
expr, module, builder, func, local_sym_tab, map_sym_tab, structs_sym_tab, local_var_metadata)
elif isinstance(expr, ast.Attribute):
if isinstance(expr.value, ast.Name):
var_name = expr.value.id
attr_name = expr.attr
if var_name in local_sym_tab:
var_ptr, var_type = local_sym_tab[var_name]
print(f"Loading attribute "
f"{attr_name} from variable {var_name}")
print(f"Variable type: {var_type}, Variable ptr: {var_ptr}")
print(local_var_metadata)
if local_var_metadata and var_name in local_var_metadata:
metadata = structs_sym_tab[local_var_metadata[var_name]]
if attr_name in metadata["fields"]:
field_idx = metadata["fields"][attr_name]
gep = builder.gep(var_ptr, [ir.Constant(ir.IntType(32), 0),
ir.Constant(ir.IntType(32), field_idx)])
val = builder.load(gep)
field_type = metadata["field_types"][field_idx]
return val, field_type
print("Unsupported expression evaluation")
return None
@ -73,6 +93,7 @@ def eval_expr(func, module, builder, expr, local_sym_tab, map_sym_tab, structs_s
def handle_expr(func, module, builder, expr, local_sym_tab, map_sym_tab, structs_sym_tab, local_var_metadata):
"""Handle expression statements in the function body."""
print(f"Handling expression: {ast.dump(expr)}")
print(local_var_metadata)
call = expr.value
if isinstance(call, ast.Call):
eval_expr(func, module, builder, call, local_sym_tab,

1
pythonbpf/functions_pass.py
View File

@ -282,6 +282,7 @@ def handle_if(func, module, builder, stmt, map_sym_tab, local_sym_tab, structs_s
def process_stmt(func, module, builder, stmt, local_sym_tab, map_sym_tab, structs_sym_tab, did_return, ret_type=ir.IntType(64)):
print(f"Processing statement: {ast.dump(stmt)}")
if isinstance(stmt, ast.Expr):
print(local_var_metadata)
handle_expr(func, module, builder, stmt, local_sym_tab,
map_sym_tab, structs_sym_tab, local_var_metadata)
elif isinstance(stmt, ast.Assign):