selftests: timers: Fix valid-adjtimex signed left-shift undefined behavior

The struct adjtimex freq field takes a signed value who's units are in
shifted (<<16) parts-per-million.

Unfortunately for negative adjustments, the straightforward use of:

freq = ppm << 16 trips undefined behavior warnings with clang:

valid-adjtimex.c:66:6: warning: shifting a negative signed value is undefined [-Wshift-negative-value]
-499<<16,
~~~~^
valid-adjtimex.c:67:6: warning: shifting a negative signed value is undefined [-Wshift-negative-value]
-450<<16,
~~~~^
..

Fix it by using a multiply by (1 << 16) instead of shifting negative values
in the valid-adjtimex test case. Align the values for better readability.

Reported-by: Lee Jones <joneslee@google.com>
Reported-by: Muhammad Usama Anjum <usama.anjum@collabora.com>
Signed-off-by: John Stultz <jstultz@google.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Muhammad Usama Anjum <usama.anjum@collabora.com>
Link: https://lore.kernel.org/r/20240409202222.2830476-1-jstultz@google.com
Link: https://lore.kernel.org/lkml/0c6d4f0d-2064-4444-986b-1d1ed782135f@collabora.com/

selftests: timers: valid-adjtimex: build fix for newer toolchains

Toolchains with an include file 'sys/timex.h' based on 3.18 will have a
'clock_adjtime' definition added, so it can't be static in the code:

valid-adjtimex.c:43:12: error: static declaration of ‘clock_adjtime’ follows non-static declaration

Fixes: e03a58c320e1 ("kselftests: timers: Add adjtimex SETOFFSET validity tests")
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Acked-by: John Stultz <jstultz@google.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

selftests/timers: Add missing fflush(stdout) calls

When running under a pipe, some timer tests would not report output in
real-time because stdout flushes were missing after printf()s that lacked
a newline. This adds them to restore real-time status output that humans
can enjoy.

Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

selftests: timers: drop support for !KTEST case

There is no need to keep timers tests in sync with external timers
repo. Drop support for !KTEST to support for building and running
timers tests without kselftest framework.

Reference: https://lkml.org/lkml/2017/8/10/952
Signed-off-by: Shuah Khan <shuahkh@osg.samsung.com>
Acked-by: John Stultz <john.stultz@linaro.org>

kselftests: timers: Add adjtimex SETOFFSET validity tests

Add some simple tests to check both valid and invalid
offsets when using adjtimex's ADJ_SETOFFSET method.

Signed-off-by: John Stultz <john.stultz@linaro.org>
Acked-by: Shuah Khan <shuahkh@osg.samsung.com>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Harald Hoyer <harald@redhat.com>
Cc: Kay Sievers <kay@vrfy.org>
Cc: David Herrmann <dh.herrmann@gmail.com>
Link: http://lkml.kernel.org/r/1453417415-19110-3-git-send-email-john.stultz@linaro.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

selftests/timers: Add adjtimex validation test from timetest suite

This adds a adjtimex validation test which checks the behavior
for a set of valida and invalid inputs. So far this only tests
ADJ_FREQUENCY, but hopefully will grow.

Cc: Shuah Khan <shuahkh@osg.samsung.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Richard Cochran <richardcochran@gmail.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Tested-by: Prarit Bhargava <prarit@redhat.com>
Signed-off-by: Shuah Khan <shuahkh@osg.samsung.com>