time: Avoid potential shift overflow with large shift values
Andreas Schwab noticed that the 1 << tk->shift could overflow if the
shift value was greater than 30, since 1 would be a 32bit long on
32bit architectures. This issue was introduced by 1e75fa8be
(time:
Condense timekeeper.xtime into xtime_sec)
Use 1ULL instead to ensure we don't overflow on the shift.
Reported-by: Andreas Schwab <schwab@linux-m68k.org>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Ingo Molnar <mingo@kernel.org>
Link: http://lkml.kernel.org/r/1345595449-34965-4-git-send-email-john.stultz@linaro.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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@ -1184,9 +1184,9 @@ static void update_wall_time(void)
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* the vsyscall implementations are converted to use xtime_nsec
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* the vsyscall implementations are converted to use xtime_nsec
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* (shifted nanoseconds), this can be killed.
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* (shifted nanoseconds), this can be killed.
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*/
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*/
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remainder = tk->xtime_nsec & ((1 << tk->shift) - 1);
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remainder = tk->xtime_nsec & ((1ULL << tk->shift) - 1);
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tk->xtime_nsec -= remainder;
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tk->xtime_nsec -= remainder;
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tk->xtime_nsec += 1 << tk->shift;
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tk->xtime_nsec += 1ULL << tk->shift;
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tk->ntp_error += remainder << tk->ntp_error_shift;
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tk->ntp_error += remainder << tk->ntp_error_shift;
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/*
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/*
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