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// SPDX-License-Identifier: GPL-2.0
/*
Description:
. Disable strace like syscall tracing (--no-syscalls), or try tracing
just some (-e *sleep).
. Attach a filter function to a kernel function, returning when it should
be considered, i.e. appear on the output.
. Run it system wide, so that any sleep of >= 5 seconds and < than 6
seconds gets caught.
. Ask for callgraphs using DWARF info, so that userspace can be unwound
. While this is running, run something like "sleep 5s".
. If we decide to add tv_nsec as well, then it becomes:
int probe(hrtimer_nanosleep, rqtp->tv_sec rqtp->tv_nsec)(void *ctx, int err, long sec, long nsec)
I.e. add where it comes from (rqtp->tv_nsec) and where it will be
accessible in the function body (nsec)
# perf trace --no-syscalls -e tools/perf/examples/bpf/5sec.c/call-graph=dwarf/
0.000 perf_bpf_probe:func:(ffffffff9811b5f0) tv_sec=5
hrtimer_nanosleep ([kernel.kallsyms])
__x64_sys_nanosleep ([kernel.kallsyms])
do_syscall_64 ([kernel.kallsyms])
entry_SYSCALL_64 ([kernel.kallsyms])
__GI___nanosleep (/usr/lib64/libc-2.26.so)
rpl_nanosleep (/usr/bin/sleep)
xnanosleep (/usr/bin/sleep)
main (/usr/bin/sleep)
__libc_start_main (/usr/lib64/libc-2.26.so)
_start (/usr/bin/sleep)
^C#
Copyright (C) 2018 Red Hat, Inc., Arnaldo Carvalho de Melo <acme@redhat.com>
*/
#include <bpf/bpf.h>
#define NSEC_PER_SEC 1000000000L
int probe(hrtimer_nanosleep, rqtp)(void *ctx, int err, long long sec)
{
return sec / NSEC_PER_SEC == 5ULL;
}
license(GPL);
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