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123 lines
3.3 KiB
123 lines
3.3 KiB
#!/usr/bin/python |
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# |
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# stacksnoop Trace a kernel function and print all kernel stack traces. |
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# For Linux, uses BCC, eBPF, and currently x86_64 only. Inline C. |
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# |
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# USAGE: stacksnoop [-h] [-p PID] [-s] [-v] function |
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# |
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# Copyright 2016 Netflix, Inc. |
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# Licensed under the Apache License, Version 2.0 (the "License") |
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# |
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# 12-Jan-2016 Brendan Gregg Created this. |
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from __future__ import print_function |
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from bcc import BPF |
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import argparse |
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import ctypes as ct |
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import time |
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# arguments |
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examples = """examples: |
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./stacksnoop ext4_sync_fs # print kernel stack traces for ext4_sync_fs |
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./stacksnoop -s ext4_sync_fs # ... also show symbol offsets |
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./stacksnoop -v ext4_sync_fs # ... show extra columns |
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./stacksnoop -p 185 ext4_sync_fs # ... only when PID 185 is on-CPU |
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""" |
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parser = argparse.ArgumentParser( |
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description="Trace and print kernel stack traces for a kernel function", |
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formatter_class=argparse.RawDescriptionHelpFormatter, |
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epilog=examples) |
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parser.add_argument("-p", "--pid", |
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help="trace this PID only") |
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parser.add_argument("-s", "--offset", action="store_true", |
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help="show address offsets") |
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parser.add_argument("-v", "--verbose", action="store_true", |
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help="print more fields") |
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parser.add_argument("function", |
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help="kernel function name") |
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args = parser.parse_args() |
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function = args.function |
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offset = args.offset |
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verbose = args.verbose |
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debug = 0 |
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# define BPF program |
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bpf_text = """ |
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#include <uapi/linux/ptrace.h> |
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#include <linux/sched.h> |
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struct data_t { |
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u64 stack_id; |
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u32 pid; |
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char comm[TASK_COMM_LEN]; |
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}; |
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BPF_STACK_TRACE(stack_traces, 128); |
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BPF_PERF_OUTPUT(events); |
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void trace_stack(struct pt_regs *ctx) { |
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u32 pid = bpf_get_current_pid_tgid(); |
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FILTER |
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struct data_t data = {}; |
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data.stack_id = stack_traces.get_stackid(ctx, BPF_F_REUSE_STACKID), |
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data.pid = pid; |
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bpf_get_current_comm(&data.comm, sizeof(data.comm)); |
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events.perf_submit(ctx, &data, sizeof(data)); |
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} |
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""" |
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if args.pid: |
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bpf_text = bpf_text.replace('FILTER', |
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'if (pid != %s) { return; }' % args.pid) |
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else: |
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bpf_text = bpf_text.replace('FILTER', '') |
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if debug: |
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print(bpf_text) |
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# initialize BPF |
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b = BPF(text=bpf_text) |
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b.attach_kprobe(event=function, fn_name="trace_stack") |
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TASK_COMM_LEN = 16 # linux/sched.h |
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class Data(ct.Structure): |
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_fields_ = [ |
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("stack_id", ct.c_ulonglong), |
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("pid", ct.c_uint), |
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("comm", ct.c_char * TASK_COMM_LEN), |
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] |
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matched = b.num_open_kprobes() |
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if matched == 0: |
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print("Function \"%s\" not found. Exiting." % function) |
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exit() |
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stack_traces = b.get_table("stack_traces") |
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start_ts = time.time() |
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# header |
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if verbose: |
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print("%-18s %-12s %-6s %-3s %s" % |
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("TIME(s)", "COMM", "PID", "CPU", "FUNCTION")) |
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else: |
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print("%-18s %s" % ("TIME(s)", "FUNCTION")) |
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def print_event(cpu, data, size): |
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event = ct.cast(data, ct.POINTER(Data)).contents |
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ts = time.time() - start_ts |
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if verbose: |
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print("%-18.9f %-12.12s %-6d %-3d %s" % |
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(ts, event.comm.decode(), event.pid, cpu, function)) |
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else: |
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print("%-18.9f %s" % (ts, function)) |
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for addr in stack_traces.walk(event.stack_id): |
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sym = b.ksym(addr, show_offset=offset) |
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print("\t%s" % sym) |
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print() |
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b["events"].open_perf_buffer(print_event) |
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while 1: |
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b.perf_buffer_poll()
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