When testing send_signal and stacktrace_build_id_nmi using the riscv sbi
pmu driver without the sscofpmf extension or the riscv legacy pmu driver,
then failures as follows are encountered:
test_send_signal_common:FAIL:perf_event_open unexpected perf_event_open: actual -1 < expected 0
#272/3 send_signal/send_signal_nmi:FAIL
test_stacktrace_build_id_nmi:FAIL:perf_event_open err -1 errno 95
#304 stacktrace_build_id_nmi:FAIL
The reason is that the above pmu driver or hardware does not support
sampling events, that is, PERF_PMU_CAP_NO_INTERRUPT is set to pmu
capabilities, and then perf_event_open returns EOPNOTSUPP. Since
PERF_PMU_CAP_NO_INTERRUPT is not only set in the riscv-related pmu driver,
it is better to skip testing when this capability is set.
Signed-off-by: Pu Lehui <pulehui@huawei.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20240402073029.1299085-1-pulehui@huaweicloud.com
The send_signal tracepoint tests are non-deterministically failing in
CI. The test works as follows:
1. Two pairs of file descriptors are created using the pipe() function.
One pair is used to communicate between a parent process -> child
process, and the other for the reverse direction.
2. A child is fork()'ed. The child process registers a signal handler,
notifies its parent that the signal handler is registered, and then
and waits for its parent to have enabled a BPF program that sends a
signal.
3. The parent opens and loads a BPF skeleton with programs that send
signals to the child process. The different programs are triggered by
different perf events (either NMI or normal perf), or by regular
tracepoints. The signal is delivered to the child whenever the child
triggers the program.
4. The child's signal handler is invoked, which sets a flag saying that
the signal handler was reached. The child then signals to the parent
that it received the signal, and the test ends.
The perf testcases (send_signal_perf{_thread} and
send_signal_nmi{_thread}) work 100% of the time, but the tracepoint
testcases fail non-deterministically because the tracepoint is not
always being fired for the child.
There are two tracepoint programs registered in the test:
'tracepoint/sched/sched_switch', and
'tracepoint/syscalls/sys_enter_nanosleep'. The child never intentionally
blocks, nor sleeps, so neither tracepoint is guaranteed to be triggered.
To fix this, we can have the child trigger the nanosleep program with a
usleep().
Before this patch, the test would fail locally every 2-3 runs. Now, it
doesn't fail after more than 1000 runs.
Signed-off-by: David Vernet <void@manifault.com>
Link: https://lore.kernel.org/r/20230310061909.1420887-1-void@manifault.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
The send_signal/send_signal_tracepoint is pretty flaky, with at least
one failure in every ten runs on a few attempts I've tried it:
> test_send_signal_common:PASS:pipe_c2p 0 nsec
> test_send_signal_common:PASS:pipe_p2c 0 nsec
> test_send_signal_common:PASS:fork 0 nsec
> test_send_signal_common:PASS:skel_open_and_load 0 nsec
> test_send_signal_common:PASS:skel_attach 0 nsec
> test_send_signal_common:PASS:pipe_read 0 nsec
> test_send_signal_common:PASS:pipe_write 0 nsec
> test_send_signal_common:PASS:reading pipe 0 nsec
> test_send_signal_common:PASS:reading pipe error: size 0 0 nsec
> test_send_signal_common:FAIL:incorrect result unexpected incorrect result: actual 48 != expected 50
> test_send_signal_common:PASS:pipe_write 0 nsec
> #139/1 send_signal/send_signal_tracepoint:FAIL
The reason does not appear to be a correctness issue in the strict
sense. Rather, we merely do not receive the signal we are waiting for
within the provided timeout.
Let's bump the timeout by a factor of ten. With that change I have not
been able to reproduce the failure in 150+ iterations. I am also sneaking
in a small simplification to the test_progs test selection logic.
Signed-off-by: Daniel Müller <deso@posteo.net>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20220727182955.4044988-1-deso@posteo.net
Building selftests/bpf with latest clang compiler (clang15 built
from source), I hit the following compilation error:
/.../prog_tests/send_signal.c:43:16: error: variable 'j' set but not used [-Werror,-Wunused-but-set-variable]
volatile int j = 0;
^
1 error generated.
The problem also exists with clang13 and clang14. clang12 is okay.
In send_signal.c, we have the following code ...
volatile int j = 0;
[...]
for (int i = 0; i < 100000000 && !sigusr1_received; i++)
j /= i + 1;
... to burn CPU cycles so bpf_send_signal() helper can be tested
in NMI mode.
Slightly changing 'j /= i + 1' to 'j /= i + j + 1' or 'j++' can
fix the problem. Further investigation indicated this should be
a clang bug ([1]). The upstream fix will be proposed later. But it
is a good idea to workaround the issue to unblock people who build
kernel/selftests with clang.
[1] https://discourse.llvm.org/t/strange-clang-unused-but-set-variable-error-with-volatile-variables/60841
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20220311003721.2177170-1-yhs@fb.com
Substitute sleep with dummy CPU intensive computation.
Finish aforemention computation as soon as signal was
delivered to the test process. Make the BPF code to
only execute when PID global variable is set
Signed-off-by: Mykola Lysenko <mykolal@fb.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20220308200449.1757478-3-mykolal@fb.com
libbpf CI has reported send_signal test is flaky although
I am not able to reproduce it in my local environment.
But I am able to reproduce with on-demand libbpf CI ([1]).
Through code analysis, the following is possible reason.
The failed subtest runs bpf program in softirq environment.
Since bpf_send_signal() only sends to a fork of "test_progs"
process. If the underlying current task is
not "test_progs", bpf_send_signal() will not be triggered
and the subtest will fail.
To reduce the chances where the underlying process is not
the intended one, this patch boosted scheduling priority to
-20 (highest allowed by setpriority() call). And I did
10 runs with on-demand libbpf CI with this patch and I
didn't observe any failures.
[1] https://github.com/libbpf/libbpf/actions/workflows/ondemand.yml
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210817190923.3186725-1-yhs@fb.com
Replace CHECK in send_signal.c with ASSERT_* macros as
ASSERT_* macros are generally preferred. There is no
funcitonality change.
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210817190918.3186400-1-yhs@fb.com
Turn ony libbpf 1.0 mode. Fix all the explicit IS_ERR checks that now will be
broken because libbpf returns NULL on error (and sets errno). Fix
ASSERT_OK_PTR and ASSERT_ERR_PTR to work for both old mode and new modes and
use them throughout selftests. This is trivial to do by using
libbpf_get_error() API that all libbpf users are supposed to use, instead of
IS_ERR checks.
A bunch of checks also did explicit -1 comparison for various fd-returning
APIs. Such checks are replaced with >= 0 or < 0 cases.
There were also few misuses of bpf_object__find_map_by_name() in test_maps.
Those are fixed in this patch as well.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/bpf/20210525035935.1461796-3-andrii@kernel.org
In preparation of skipping emitting static variables in BPF skeletons, switch
all current selftests uses of static variables to pass data between BPF and
user-space to use global variables.
All non-read-only `static volatile` variables become just plain global
variables by dropping `static volatile` part.
Read-only `static volatile const` variables, though, still require `volatile`
modifier, otherwise compiler will ignore whatever values are set from
user-space.
Few static linker tests are using name-conflicting static variables to
validate that static linker still properly handles static variables and
doesn't trip up on name conflicts.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210507054119.270888-4-andrii@kernel.org
Clang compiler version: 12.0.0
The following warning appears during the selftests/bpf compilation:
prog_tests/send_signal.c:51:3: warning: ignoring return value of ‘write’,
declared with attribute warn_unused_result [-Wunused-result]
51 | write(pipe_c2p[1], buf, 1);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~
prog_tests/send_signal.c:54:3: warning: ignoring return value of ‘read’,
declared with attribute warn_unused_result [-Wunused-result]
54 | read(pipe_p2c[0], buf, 1);
| ^~~~~~~~~~~~~~~~~~~~~~~~~
......
prog_tests/stacktrace_build_id_nmi.c:13:2: warning: ignoring return value
of ‘fscanf’,declared with attribute warn_unused_result [-Wunused-resul]
13 | fscanf(f, "%llu", &sample_freq);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
test_tcpnotify_user.c:133:2: warning:ignoring return value of ‘system’,
declared with attribute warn_unused_result [-Wunused-result]
133 | system(test_script);
| ^~~~~~~~~~~~~~~~~~~
test_tcpnotify_user.c:138:2: warning:ignoring return value of ‘system’,
declared with attribute warn_unused_result [-Wunused-result]
138 | system(test_script);
| ^~~~~~~~~~~~~~~~~~~
test_tcpnotify_user.c:143:2: warning:ignoring return value of ‘system’,
declared with attribute warn_unused_result [-Wunused-result]
143 | system(test_script);
| ^~~~~~~~~~~~~~~~~~~
Add code that fix compilation warning about ignoring return value and
handles any errors; Check return value of library`s API make the code
more secure.
Signed-off-by: Jianlin Lv <Jianlin.Lv@arm.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200806104224.95306-1-Jianlin.Lv@arm.com
Alexei observed that test_progs send_signal may fail if run
with command line "./test_progs" and the tests will pass
if just run "./test_progs -n 40".
I observed similar issue with nmi subtest failure
and added a delay 100 us in Commit ab8b7f0cb3
("tools/bpf: Add self tests for bpf_send_signal_thread()")
and the problem is gone for me. But the issue still exists
in Alexei's testing environment.
The current code uses sample_freq = 50 (50 events/second), which
may not be enough. But if the sample_freq value is larger than
sysctl kernel/perf_event_max_sample_rate, the perf_event_open
syscall will fail.
This patch changed nmi perf testing to use sample_period = 1,
which means trying to sampling every event. This seems fixing
the issue.
Fixes: ab8b7f0cb3 ("tools/bpf: Add self tests for bpf_send_signal_thread()")
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200116174004.1522812-1-yhs@fb.com
The test_progs send_signal() is amended to test
bpf_send_signal_thread() as well.
$ ./test_progs -n 40
#40/1 send_signal_tracepoint:OK
#40/2 send_signal_perf:OK
#40/3 send_signal_nmi:OK
#40/4 send_signal_tracepoint_thread:OK
#40/5 send_signal_perf_thread:OK
#40/6 send_signal_nmi_thread:OK
#40 send_signal:OK
Summary: 1/6 PASSED, 0 SKIPPED, 0 FAILED
Also took this opportunity to rewrite the send_signal test
using skeleton framework and array mmap to make code
simpler and more readable.
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200115035003.602425-1-yhs@fb.com
send_signal test returns static codes from the subtests which
nobody looks at, let's rely on the CHECK macros instead.
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Export test__skip() to indicate skipped tests and use it in
test_send_signal_nmi().
Cc: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Now that test__printf is a simple wraper around printf, let's drop it
(and test__vprintf as well).
Cc: Andrii Nakryiko <andriin@fb.com>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Convert send_signal set of tests to be exposed as three sub-tests.
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This patch changes how test output is printed out. By default, if test
had no errors, the only output will be a single line with test number,
name, and verdict at the end, e.g.:
#31 xdp:OK
If test had any errors, all log output captured during test execution
will be output after test completes.
It's possible to force output of log with `-v` (`--verbose`) option, in
which case output won't be buffered and will be output immediately.
To support this, individual tests are required to use helper methods for
logging: `test__printf()` and `test__vprintf()`.
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Some setups (e.g. virtual machines) might run with hardware perf events
disabled. If this is the case, skip the test_send_signal_nmi test.
Add a separate test involving a software perf event. This allows testing
the perf event path regardless of hardware perf event support.
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
