ea2d1f7fce
clock_nanosleep() accepts absolute values of expiration time when TIMER_ABSTIME flag is set. This absolute value is inside the task's time namespace, and has to be converted to the host's time. There is timens_ktime_to_host() helper for converting time, but it accepts ktime argument. As a preparation, make hrtimer_nanosleep() accept a clock value in ktime instead of timespec64. Co-developed-by: Dmitry Safonov <dima@arista.com> Signed-off-by: Andrei Vagin <avagin@openvz.org> Signed-off-by: Dmitry Safonov <dima@arista.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lore.kernel.org/r/20191112012724.250792-17-dima@arista.com
52 lines
2.0 KiB
C
52 lines
2.0 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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Description:
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. Disable strace like syscall tracing (--no-syscalls), or try tracing
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just some (-e *sleep).
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. Attach a filter function to a kernel function, returning when it should
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be considered, i.e. appear on the output.
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. Run it system wide, so that any sleep of >= 5 seconds and < than 6
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seconds gets caught.
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. Ask for callgraphs using DWARF info, so that userspace can be unwound
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. While this is running, run something like "sleep 5s".
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. If we decide to add tv_nsec as well, then it becomes:
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int probe(hrtimer_nanosleep, rqtp->tv_sec rqtp->tv_nsec)(void *ctx, int err, long sec, long nsec)
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I.e. add where it comes from (rqtp->tv_nsec) and where it will be
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accessible in the function body (nsec)
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# perf trace --no-syscalls -e tools/perf/examples/bpf/5sec.c/call-graph=dwarf/
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0.000 perf_bpf_probe:func:(ffffffff9811b5f0) tv_sec=5
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hrtimer_nanosleep ([kernel.kallsyms])
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__x64_sys_nanosleep ([kernel.kallsyms])
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do_syscall_64 ([kernel.kallsyms])
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entry_SYSCALL_64 ([kernel.kallsyms])
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__GI___nanosleep (/usr/lib64/libc-2.26.so)
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rpl_nanosleep (/usr/bin/sleep)
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xnanosleep (/usr/bin/sleep)
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main (/usr/bin/sleep)
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__libc_start_main (/usr/lib64/libc-2.26.so)
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_start (/usr/bin/sleep)
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^C#
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Copyright (C) 2018 Red Hat, Inc., Arnaldo Carvalho de Melo <acme@redhat.com>
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*/
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#include <bpf.h>
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#define NSEC_PER_SEC 1000000000L
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int probe(hrtimer_nanosleep, rqtp)(void *ctx, int err, long long sec)
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{
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return sec / NSEC_PER_SEC == 5ULL;
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}
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license(GPL);
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