Open
Description
Crash report
I've been using eBPF with the static markers in Python 3.10 and wanted to try out 3.11 now that it is released.
But it seems that the function__entry and line markers are broken in 3.11.
The function__entry probe simply does not fire into the eBPF program.
The line probe crashes the interpreter.
I'm using BCC to load the eBPF program like this:
#!/usr/bin/python3
import argparse
from bcc import BPF, USDT
parser = argparse.ArgumentParser()
parser.add_argument("pid", type=int)
args = parser.parse_args()
program = """
int trace_entry(struct pt_regs *ctx) {
bpf_trace_printk("Entry:");
return 0;
}
int trace_return(struct pt_regs *ctx) {
bpf_trace_printk("Return:");
return 0;
}
int trace_line(struct pt_regs *ctx) {
bpf_trace_printk("Line:");
return 0;
}
"""
usdt = USDT(pid=args.pid)
usdt.enable_probe_or_bail("python:function__entry", 'trace_entry')
usdt.enable_probe_or_bail("python:function__return", 'trace_return')
usdt.enable_probe_or_bail("python:line", 'trace_line')
bpf = BPF(text=program, usdt_contexts=[usdt] if usdt else [], debug=0)
try:
bpf.trace_print()
except KeyboardInterrupt:
exit()
If I don't enable the line probe this is the output:
❯ sudo ./ebpf-test.py 80715
b' python-80715 [001] d...1 6539.145626: bpf_trace_printk: Return:'
The entry message is never printed.
Error messages
With the line probe enabled, this is the crash error:
❯ ./python
Python 3.11.0+ (heads/3.11:57dd11038f, Oct 31 2022, 10:30:28) [GCC 11.3.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> print("Hello world!")
python: Python/ceval.c:5620: _PyEval_EvalFrameDefault: Assertion `cframe.use_tracing' failed.
[1] 80398 IOT instruction (core dumped) ./python
Expected result
Running the same test in 3.10.6 I get this result, as expected:
❯ python3
Python 3.10.6 (main, Aug 10 2022, 11:40:04) [GCC 11.3.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> print("Hello world!")
Hello world!
❯ sudo ./ebpf-test.py 81962
b' python3-81962 [003] d...1 6907.857690: bpf_trace_printk: Entry:'
b' python3-81962 [003] d...1 6907.857710: bpf_trace_printk: Line:'
b' python3-81962 [003] d...1 6907.857765: bpf_trace_printk: Return:'
Your environment
I used the head of the 3.11 branch with ./configure --with-dtrace --with-pydebug
On Ubuntu 22.04.