You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
128 lines
3.8 KiB
128 lines
3.8 KiB
#!/usr/bin/env python
|
|
#
|
|
# stacksnoop Trace a kernel function and print all kernel stack traces.
|
|
# For Linux, uses BCC, eBPF, and currently x86_64 only. Inline C.
|
|
#
|
|
# USAGE: stacksnoop [-h] [-p PID] [-s] [-v] function
|
|
#
|
|
# The current implementation uses an unrolled loop for x86_64, and was written
|
|
# as a proof of concept. This implementation should be replaced in the future
|
|
# with an appropriate bpf_ call, when available.
|
|
#
|
|
# The stack depth is limited to 10 (+1 for the current instruction pointer).
|
|
# This could be tunable in a future version.
|
|
#
|
|
# Copyright 2016 Netflix, Inc.
|
|
# Licensed under the Apache License, Version 2.0 (the "License")
|
|
#
|
|
# 12-Jan-2016 Brendan Gregg Created this.
|
|
|
|
from __future__ import print_function
|
|
from bcc import BPF
|
|
import argparse
|
|
|
|
# arguments
|
|
examples = """examples:
|
|
./stacksnoop ext4_sync_fs # print kernel stack traces for ext4_sync_fs
|
|
./stacksnoop -s ext4_sync_fs # ... also show symbol offsets
|
|
./stacksnoop -v ext4_sync_fs # ... show extra columns
|
|
./stacksnoop -p 185 ext4_sync_fs # ... only when PID 185 is on-CPU
|
|
"""
|
|
parser = argparse.ArgumentParser(
|
|
description="Trace and print kernel stack traces for a kernel function",
|
|
formatter_class=argparse.RawDescriptionHelpFormatter,
|
|
epilog=examples)
|
|
parser.add_argument("-p", "--pid",
|
|
help="trace this PID only")
|
|
parser.add_argument("-s", "--offset", action="store_true",
|
|
help="show address offsets")
|
|
parser.add_argument("-v", "--verbose", action="store_true",
|
|
help="print more fields")
|
|
parser.add_argument("function",
|
|
help="kernel function name")
|
|
args = parser.parse_args()
|
|
function = args.function
|
|
offset = args.offset
|
|
verbose = args.verbose
|
|
debug = 0
|
|
|
|
# define BPF program
|
|
bpf_text = """
|
|
#include <uapi/linux/ptrace.h>
|
|
|
|
static int print_frame(u64 *bp, int *depth) {
|
|
if (*bp) {
|
|
// The following stack walker is x86_64 specific
|
|
u64 ret = 0;
|
|
if (bpf_probe_read(&ret, sizeof(ret), (void *)(*bp+8)))
|
|
return 0;
|
|
if (ret < __START_KERNEL_map)
|
|
return 0;
|
|
bpf_trace_printk("r%d: %llx\\n", *depth, ret);
|
|
if (bpf_probe_read(bp, sizeof(*bp), (void *)*bp))
|
|
return 0;
|
|
*depth += 1;
|
|
return 1;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
void trace_stack(struct pt_regs *ctx) {
|
|
FILTER
|
|
u64 bp = 0;
|
|
int depth = 0;
|
|
|
|
bpf_trace_printk("\\n");
|
|
if (ctx->ip)
|
|
bpf_trace_printk("ip: %llx\\n", ctx->ip);
|
|
bp = ctx->bp;
|
|
|
|
// unrolled loop, 10 frames deep:
|
|
if (!print_frame(&bp, &depth)) return;
|
|
if (!print_frame(&bp, &depth)) return;
|
|
if (!print_frame(&bp, &depth)) return;
|
|
if (!print_frame(&bp, &depth)) return;
|
|
if (!print_frame(&bp, &depth)) return;
|
|
if (!print_frame(&bp, &depth)) return;
|
|
if (!print_frame(&bp, &depth)) return;
|
|
if (!print_frame(&bp, &depth)) return;
|
|
if (!print_frame(&bp, &depth)) return;
|
|
if (!print_frame(&bp, &depth)) return;
|
|
};
|
|
"""
|
|
if args.pid:
|
|
bpf_text = bpf_text.replace('FILTER',
|
|
('u32 pid; pid = bpf_get_current_pid_tgid(); ' +
|
|
'if (pid != %s) { return; }') % (args.pid))
|
|
else:
|
|
bpf_text = bpf_text.replace('FILTER', '')
|
|
if debug:
|
|
print(bpf_text)
|
|
|
|
# initialize BPF
|
|
b = BPF(text=bpf_text)
|
|
b.attach_kprobe(event=function, fn_name="trace_stack")
|
|
matched = b.num_open_kprobes()
|
|
if matched == 0:
|
|
print("Function \"%s\" not found. Exiting." % function)
|
|
exit()
|
|
|
|
# header
|
|
if verbose:
|
|
print("%-18s %-12s %-6s %-3s %s" % ("TIME(s)", "COMM", "PID", "CPU",
|
|
"STACK"))
|
|
else:
|
|
print("%-18s %s" % ("TIME(s)", "STACK"))
|
|
|
|
# format output
|
|
while 1:
|
|
(task, pid, cpu, flags, ts, msg) = b.trace_fields()
|
|
if msg != "":
|
|
(reg, addr) = msg.split(" ")
|
|
ip = b.ksym(int(addr, 16), show_offset=offset)
|
|
msg = msg + " " + ip
|
|
if verbose:
|
|
print("%-18.9f %-12.12s %-6d %-3d %s" % (ts, task, pid, cpu, msg))
|
|
else:
|
|
print("%-18.9f %s" % (ts, msg))
|