From 6eb4f08293e971cb1b7b867c7fe994c244b91460 Mon Sep 17 00:00:00 2001 From: Jacob Pan Date: Thu, 25 Apr 2019 10:27:52 -0700 Subject: [PATCH] x86/apic: Unify duplicated local apic timer clockevent initialization Local APIC timer clockevent parameters can be calculated based on platform specific methods. However the code is mostly duplicated with the interrupt based calibration. The commit which increased the max_delta parameter updated only one place and made the implementations diverge. Unify it to prevent further damage. [ tglx: Rename function to lapic_init_clockevent() and adjust changelog a bit ] Fixes: 4aed89d6b515 ("x86, lapic-timer: Increase the max_delta to 31 bits") Reported-by: Daniel Drake Signed-off-by: Jacob Pan Signed-off-by: Thomas Gleixner Cc: Len Brown Link: https://lkml.kernel.org/r/1556213272-63568-1-git-send-email-jacob.jun.pan@linux.intel.com --- arch/x86/kernel/apic/apic.c | 57 ++++++++++++++++++++++++--------------------- 1 file changed, 31 insertions(+), 26 deletions(-) diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c index b7bcdd7..ab6af77 100644 --- a/arch/x86/kernel/apic/apic.c +++ b/arch/x86/kernel/apic/apic.c @@ -802,6 +802,24 @@ calibrate_by_pmtimer(long deltapm, long *delta, long *deltatsc) return 0; } +static int __init lapic_init_clockevent(void) +{ + if (!lapic_timer_frequency) + return -1; + + /* Calculate the scaled math multiplication factor */ + lapic_clockevent.mult = div_sc(lapic_timer_frequency/APIC_DIVISOR, + TICK_NSEC, lapic_clockevent.shift); + lapic_clockevent.max_delta_ns = + clockevent_delta2ns(0x7FFFFFFF, &lapic_clockevent); + lapic_clockevent.max_delta_ticks = 0x7FFFFFFF; + lapic_clockevent.min_delta_ns = + clockevent_delta2ns(0xF, &lapic_clockevent); + lapic_clockevent.min_delta_ticks = 0xF; + + return 0; +} + static int __init calibrate_APIC_clock(void) { struct clock_event_device *levt = this_cpu_ptr(&lapic_events); @@ -810,25 +828,21 @@ static int __init calibrate_APIC_clock(void) long delta, deltatsc; int pm_referenced = 0; - /** - * check if lapic timer has already been calibrated by platform - * specific routine, such as tsc calibration code. if so, we just fill + if (boot_cpu_has(X86_FEATURE_TSC_DEADLINE_TIMER)) + return 0; + + /* + * Check if lapic timer has already been calibrated by platform + * specific routine, such as tsc calibration code. If so just fill * in the clockevent structure and return. */ - - if (boot_cpu_has(X86_FEATURE_TSC_DEADLINE_TIMER)) { - return 0; - } else if (lapic_timer_frequency) { + if (!lapic_init_clockevent()) { apic_printk(APIC_VERBOSE, "lapic timer already calibrated %d\n", - lapic_timer_frequency); - lapic_clockevent.mult = div_sc(lapic_timer_frequency/APIC_DIVISOR, - TICK_NSEC, lapic_clockevent.shift); - lapic_clockevent.max_delta_ns = - clockevent_delta2ns(0x7FFFFF, &lapic_clockevent); - lapic_clockevent.max_delta_ticks = 0x7FFFFF; - lapic_clockevent.min_delta_ns = - clockevent_delta2ns(0xF, &lapic_clockevent); - lapic_clockevent.min_delta_ticks = 0xF; + lapic_timer_frequency); + /* + * Direct calibration methods must have an always running + * local APIC timer, no need for broadcast timer. + */ lapic_clockevent.features &= ~CLOCK_EVT_FEAT_DUMMY; return 0; } @@ -869,17 +883,8 @@ static int __init calibrate_APIC_clock(void) pm_referenced = !calibrate_by_pmtimer(lapic_cal_pm2 - lapic_cal_pm1, &delta, &deltatsc); - /* Calculate the scaled math multiplication factor */ - lapic_clockevent.mult = div_sc(delta, TICK_NSEC * LAPIC_CAL_LOOPS, - lapic_clockevent.shift); - lapic_clockevent.max_delta_ns = - clockevent_delta2ns(0x7FFFFFFF, &lapic_clockevent); - lapic_clockevent.max_delta_ticks = 0x7FFFFFFF; - lapic_clockevent.min_delta_ns = - clockevent_delta2ns(0xF, &lapic_clockevent); - lapic_clockevent.min_delta_ticks = 0xF; - lapic_timer_frequency = (delta * APIC_DIVISOR) / LAPIC_CAL_LOOPS; + lapic_init_clockevent(); apic_printk(APIC_VERBOSE, "..... delta %ld\n", delta); apic_printk(APIC_VERBOSE, "..... mult: %u\n", lapic_clockevent.mult); -- 2.7.4