FM / tracing

/usr/share/doc/bpfcc-tools/examples/tracing/

/usr/share/doc/bpfcc-tools/examples/tracing

Name	Size	Mode	Actions
biolatpcts.py	3312	0755	edit dl rm
biolatpcts_example.txt	650	0644	edit dl rm
bitehist.py	1397	0755	edit dl rm
bitehist_example.txt	1208	0644	edit dl rm
CMakeLists.txt	276	0644	edit dl rm
dddos.py	3818	0755	edit dl rm
dddos_example.txt	2112	0644	edit dl rm
disksnoop.py	1947	0755	edit dl rm
disksnoop_example.txt	1587	0644	edit dl rm
hello_fields.py	679	0755	edit dl rm
hello_perf_output.py	1270	0755	edit dl rm
hello_perf_output_using_ns.py	1843	0755	edit dl rm
kvm_hypercall.py	1520	0755	edit dl rm
kvm_hypercall.txt	1782	0644	edit dl rm
mallocstacks.py	1942	0755	edit dl rm
mysqld_query.py	1701	0755	edit dl rm
mysqld_query_example.txt	499	0644	edit dl rm
nflatency.py	6214	0755	edit dl rm
nodejs_http_server.py	1376	0755	edit dl rm
nodejs_http_server_example.txt	276	0644	edit dl rm
stacksnoop.py	3252	0755	edit dl rm
stacksnoop_example.txt	2871	0644	edit dl rm
stack_buildid_example.py	3106	0755	edit dl rm
strlen_count.py	1331	0755	edit dl rm
strlen_hist.py	1856	0755	edit dl rm
strlen_hist_ifunc.py	3800	0755	edit dl rm
strlen_snoop.py	1384	0755	edit dl rm
sync_timing.py	1390	0755	edit dl rm
task_switch.c	499	0644	edit dl rm
task_switch.py	486	0755	edit dl rm
tcpv4connect.py	2413	0755	edit dl rm
tcpv4connect_example.txt	1063	0644	edit dl rm
trace_fields.py	589	0755	edit dl rm
trace_perf_output.py	1600	0755	edit dl rm
undump.py	3602	0755	edit dl rm
undump_example.txt	886	0644	edit dl rm
urandomread-explicit.py	1511	0755	edit dl rm
urandomread.py	1032	0755	edit dl rm
urandomread_example.txt	675	0644	edit dl rm
vfsreadlat.c	896	0644	edit dl rm
vfsreadlat.py	1336	0755	edit dl rm
vfsreadlat_example.txt	3619	0644	edit dl rm

Edit: /usr/share/doc/bpfcc-tools/examples/tracing/strlen_count.py (1331B)

#!/usr/bin/python
#
# strlen_count  Trace strlen() and print a frequency count of strings.
#               For Linux, uses BCC, eBPF. Embedded C.
#
# Written as a basic example of BCC and uprobes.
#
# Also see strlensnoop.
#
# Copyright 2016 Netflix, Inc.
# Licensed under the Apache License, Version 2.0 (the "License")

from __future__ import print_function
from bcc import BPF
from bcc.utils import printb
from time import sleep

# load BPF program
b = BPF(text="""
#include <uapi/linux/ptrace.h>

struct key_t {
    char c[80];
};
BPF_HASH(counts, struct key_t);

int count(struct pt_regs *ctx) {
    if (!PT_REGS_PARM1(ctx))
        return 0;

struct key_t key = {};
    u64 zero = 0, *val;

bpf_probe_read_user(&key.c, sizeof(key.c), (void *)PT_REGS_PARM1(ctx));
    // could also use `counts.increment(key)`
    val = counts.lookup_or_try_init(&key, &zero);
    if (val) {
      (*val)++;
    }
    return 0;
};
""")
b.attach_uprobe(name="c", sym="strlen", fn_name="count")

# header
print("Tracing strlen()... Hit Ctrl-C to end.")

# sleep until Ctrl-C
try:
    sleep(99999999)
except KeyboardInterrupt:
    pass

# print output
print("%10s %s" % ("COUNT", "STRING"))
counts = b.get_table("counts")
for k, v in sorted(counts.items(), key=lambda counts: counts[1].value):
    printb(b"%10d \"%s\"" % (v.value, k.c))

cmd: