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Copy pathtracepoint.py
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142 lines (127 loc) · 5.43 KB
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# Copyright 2016 Sasha Goldshtein
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
import ctypes as ct
import multiprocessing
import os
import re
class Tracepoint(object):
enabled_tracepoints = []
trace_root = "/sys/kernel/debug/tracing"
event_root = os.path.join(trace_root, "events")
@classmethod
def _any_tracepoints_enabled(cls):
return len(cls.enabled_tracepoints) > 0
@classmethod
def generate_decl(cls):
if not cls._any_tracepoints_enabled():
return ""
return "\nBPF_HASH(__trace_di, u64, u64);\n"
@classmethod
def generate_entry_probe(cls):
if not cls._any_tracepoints_enabled():
return ""
return """
int __trace_entry_update(struct pt_regs *ctx)
{
u64 tid = bpf_get_current_pid_tgid();
u64 val = PT_REGS_PARM1(ctx);
__trace_di.update(&tid, &val);
return 0;
}
"""
def __init__(self, category, event, tp_id):
self.category = category
self.event = event
self.tp_id = tp_id
self._retrieve_struct_fields()
def _retrieve_struct_fields(self):
self.struct_fields = []
format_lines = Tracepoint.get_tpoint_format(self.category,
self.event)
for line in format_lines:
match = re.search(r'field:([^;]*);.*size:(\d+);', line)
if match is None:
continue
parts = match.group(1).split()
field_name = parts[-1:][0]
field_type = " ".join(parts[:-1])
field_size = int(match.group(2))
if "__data_loc" in field_type:
continue
if field_name.startswith("common_"):
continue
self.struct_fields.append((field_type, field_name))
def _generate_struct_fields(self):
text = ""
for field_type, field_name in self.struct_fields:
text += " %s %s;\n" % (field_type, field_name)
return text
def generate_struct(self):
self.struct_name = self.event + "_trace_entry"
return """
struct %s {
u64 __do_not_use__;
%s
};
""" % (self.struct_name, self._generate_struct_fields())
def _generate_struct_locals(self):
text = ""
for field_type, field_name in self.struct_fields:
if field_type == "char" and field_name.endswith(']'):
# Special case for 'char whatever[N]', should
# be assigned to a 'char *'
field_type = "char *"
field_name = re.sub(r'\[\d+\]$', '', field_name)
text += " %s %s = tp.%s;\n" % (
field_type, field_name, field_name)
return text
def generate_get_struct(self):
return """
u64 tid = bpf_get_current_pid_tgid();
u64 *di = __trace_di.lookup(&tid);
if (di == 0) { return 0; }
struct %s tp = {};
bpf_probe_read(&tp, sizeof(tp), (void *)*di);
%s
""" % (self.struct_name, self._generate_struct_locals())
@classmethod
def enable_tracepoint(cls, category, event):
tp_id = cls.get_tpoint_id(category, event)
if tp_id == -1:
raise ValueError("no such tracepoint found: %s:%s" %
(category, event))
Perf.perf_event_open(tp_id, ptype=Perf.PERF_TYPE_TRACEPOINT)
new_tp = Tracepoint(category, event, tp_id)
cls.enabled_tracepoints.append(new_tp)
return new_tp
@staticmethod
def get_tpoint_id(category, event):
evt_dir = os.path.join(Tracepoint.event_root, category, event)
try:
return int(
open(os.path.join(evt_dir, "id")).read().strip())
except:
return -1
@staticmethod
def get_tpoint_format(category, event):
evt_dir = os.path.join(Tracepoint.event_root, category, event)
try:
return open(os.path.join(evt_dir, "format")).readlines()
except:
return ""
@classmethod
def attach(cls, bpf):
if cls._any_tracepoints_enabled():
bpf.attach_kprobe(event="tracing_generic_entry_update",
fn_name="__trace_entry_update")