5sec.c (1998B)
1// SPDX-License-Identifier: GPL-2.0 2/* 3 Description: 4 5 . Disable strace like syscall tracing (--no-syscalls), or try tracing 6 just some (-e *sleep). 7 8 . Attach a filter function to a kernel function, returning when it should 9 be considered, i.e. appear on the output. 10 11 . Run it system wide, so that any sleep of >= 5 seconds and < than 6 12 seconds gets caught. 13 14 . Ask for callgraphs using DWARF info, so that userspace can be unwound 15 16 . While this is running, run something like "sleep 5s". 17 18 . If we decide to add tv_nsec as well, then it becomes: 19 20 int probe(hrtimer_nanosleep, rqtp->tv_sec rqtp->tv_nsec)(void *ctx, int err, long sec, long nsec) 21 22 I.e. add where it comes from (rqtp->tv_nsec) and where it will be 23 accessible in the function body (nsec) 24 25 # perf trace --no-syscalls -e tools/perf/examples/bpf/5sec.c/call-graph=dwarf/ 26 0.000 perf_bpf_probe:func:(ffffffff9811b5f0) tv_sec=5 27 hrtimer_nanosleep ([kernel.kallsyms]) 28 __x64_sys_nanosleep ([kernel.kallsyms]) 29 do_syscall_64 ([kernel.kallsyms]) 30 entry_SYSCALL_64 ([kernel.kallsyms]) 31 __GI___nanosleep (/usr/lib64/libc-2.26.so) 32 rpl_nanosleep (/usr/bin/sleep) 33 xnanosleep (/usr/bin/sleep) 34 main (/usr/bin/sleep) 35 __libc_start_main (/usr/lib64/libc-2.26.so) 36 _start (/usr/bin/sleep) 37 ^C# 38 39 Copyright (C) 2018 Red Hat, Inc., Arnaldo Carvalho de Melo <acme@redhat.com> 40*/ 41 42#include <bpf.h> 43 44#define NSEC_PER_SEC 1000000000L 45 46int probe(hrtimer_nanosleep, rqtp)(void *ctx, int err, long long sec) 47{ 48 return sec / NSEC_PER_SEC == 5ULL; 49} 50 51license(GPL);