• Thomas Gleixner's avatar
    clocksource: Move cycle_last validation to core code · 09ec5442
    Thomas Gleixner authored
    The only user of the cycle_last validation is the x86 TSC. In order to
    provide NMI safe accessor functions for clock monotonic and
    monotonic_raw we need to do that in the core.
    
    We can't do the TSC specific
    
        if (now < cycle_last)
           	    now = cycle_last;
    
    for the other wrapping around clocksources, but TSC has
    CLOCKSOURCE_MASK(64) which actually does not mask out anything so if
    now is less than cycle_last the subtraction will give a negative
    result. So we can check for that in clocksource_delta() and return 0
    for that case.
    
    Implement and enable it for x86
    Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
    Signed-off-by: default avatarJohn Stultz <john.stultz@linaro.org>
    09ec5442
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