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Date: Tue, 9 Apr 2024 13:22:12 -0700
From: John Stultz <jstultz@...gle.com>
To: LKML <linux-kernel@...r.kernel.org>
Cc: John Stultz <jstultz@...gle.com>, Thomas Gleixner <tglx@...utronix.de>,
Stephen Boyd <sboyd@...nel.org>, Anna-Maria Behnsen <anna-maria@...utronix.de>,
Frederic Weisbecker <frederic@...nel.org>, Shuah Khan <shuah@...nel.org>,
Nathan Chancellor <nathan@...nel.org>, Nick Desaulniers <ndesaulniers@...gle.com>,
Lee Jones <joneslee@...gle.com>, Muhammad Usama Anjum <usama.anjum@...labora.com>,
linux-kselftest@...r.kernel.org
Subject: [PATCH] selftests: timers: Fix valid-adjtimex signed left-shift
undefined behavior
So, 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
will trip 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,
~~~~^
..
So fix our use of shifting negative values in the valid-adjtimex
test case to use multiply by (1<<16) to avoid this.
The patch also aligns the values a bit to make it look nicer.
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Stephen Boyd <sboyd@...nel.org>
Cc: Anna-Maria Behnsen <anna-maria@...utronix.de>
Cc: Frederic Weisbecker <frederic@...nel.org>
Cc: Shuah Khan <shuah@...nel.org>
Cc: Nathan Chancellor <nathan@...nel.org>
Cc: Nick Desaulniers <ndesaulniers@...gle.com>
Cc: Lee Jones <joneslee@...gle.com>
Cc: Muhammad Usama Anjum <usama.anjum@...labora.com>
Cc: linux-kselftest@...r.kernel.org
Reported-by: Lee Jones <joneslee@...gle.com>
Reported-by: Muhammad Usama Anjum <usama.anjum@...labora.com>
Link: https://lore.kernel.org/lkml/0c6d4f0d-2064-4444-986b-1d1ed782135f@collabora.com/
Signed-off-by: John Stultz <jstultz@...gle.com>
---
.../testing/selftests/timers/valid-adjtimex.c | 69 ++++++++++---------
1 file changed, 35 insertions(+), 34 deletions(-)
diff --git a/tools/testing/selftests/timers/valid-adjtimex.c b/tools/testing/selftests/timers/valid-adjtimex.c
index 48b9a803235a..9606d45767e7 100644
--- a/tools/testing/selftests/timers/valid-adjtimex.c
+++ b/tools/testing/selftests/timers/valid-adjtimex.c
@@ -62,45 +62,46 @@ int clear_time_state(void)
#define NUM_FREQ_OUTOFRANGE 4
#define NUM_FREQ_INVALID 2
+#define SHIFTED_PPM (1 << 16)
long valid_freq[NUM_FREQ_VALID] = {
- -499<<16,
- -450<<16,
- -400<<16,
- -350<<16,
- -300<<16,
- -250<<16,
- -200<<16,
- -150<<16,
- -100<<16,
- -75<<16,
- -50<<16,
- -25<<16,
- -10<<16,
- -5<<16,
- -1<<16,
+ -499 * SHIFTED_PPM,
+ -450 * SHIFTED_PPM,
+ -400 * SHIFTED_PPM,
+ -350 * SHIFTED_PPM,
+ -300 * SHIFTED_PPM,
+ -250 * SHIFTED_PPM,
+ -200 * SHIFTED_PPM,
+ -150 * SHIFTED_PPM,
+ -100 * SHIFTED_PPM,
+ -75 * SHIFTED_PPM,
+ -50 * SHIFTED_PPM,
+ -25 * SHIFTED_PPM,
+ -10 * SHIFTED_PPM,
+ -5 * SHIFTED_PPM,
+ -1 * SHIFTED_PPM,
-1000,
- 1<<16,
- 5<<16,
- 10<<16,
- 25<<16,
- 50<<16,
- 75<<16,
- 100<<16,
- 150<<16,
- 200<<16,
- 250<<16,
- 300<<16,
- 350<<16,
- 400<<16,
- 450<<16,
- 499<<16,
+ 1 * SHIFTED_PPM,
+ 5 * SHIFTED_PPM,
+ 10 * SHIFTED_PPM,
+ 25 * SHIFTED_PPM,
+ 50 * SHIFTED_PPM,
+ 75 * SHIFTED_PPM,
+ 100 * SHIFTED_PPM,
+ 150 * SHIFTED_PPM,
+ 200 * SHIFTED_PPM,
+ 250 * SHIFTED_PPM,
+ 300 * SHIFTED_PPM,
+ 350 * SHIFTED_PPM,
+ 400 * SHIFTED_PPM,
+ 450 * SHIFTED_PPM,
+ 499 * SHIFTED_PPM,
};
long outofrange_freq[NUM_FREQ_OUTOFRANGE] = {
- -1000<<16,
- -550<<16,
- 550<<16,
- 1000<<16,
+ -1000 * SHIFTED_PPM,
+ -550 * SHIFTED_PPM,
+ 550 * SHIFTED_PPM,
+ 1000 * SHIFTED_PPM,
};
#define LONG_MAX (~0UL>>1)
--
2.44.0.478.gd926399ef9-goog
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