From 0d651e4e65e96989f72236bf83bd4c6e55eb6ce4 Mon Sep 17 00:00:00 2001 From: Mark Rutland Date: Wed, 30 Jan 2013 17:51:26 +0000 Subject: clocksource: arch_timer: use virtual counters Switching between reading the virtual or physical counters is problematic, as some core code wants a view of time before we're fully set up. Using a function pointer and switching the source after the first read can make time appear to go backwards, and having a check in the read function is an unfortunate block on what we want to be a fast path. Instead, this patch makes us always use the virtual counters. If we're a guest, or don't have hyp mode, we'll use the virtual timers, and as such don't care about CNTVOFF as long as it doesn't change in such a way as to make time appear to travel backwards. As the guest will use the virtual timers, a (potential) KVM host must use the physical timers (which can wake up the host even if they fire while a guest is executing), and hence a host must have CNTVOFF set to zero so as to have a consistent view of time between the physical timers and virtual counters. Signed-off-by: Mark Rutland Acked-by: Catalin Marinas Acked-by: Marc Zyngier Acked-by: Santosh Shilimkar Cc: Rob Herring --- drivers/clocksource/arm_arch_timer.c | 23 +++++------------------ 1 file changed, 5 insertions(+), 18 deletions(-) (limited to 'drivers/clocksource/arm_arch_timer.c') diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c index a2b254189782..053d846ab5b1 100644 --- a/drivers/clocksource/arm_arch_timer.c +++ b/drivers/clocksource/arm_arch_timer.c @@ -186,27 +186,19 @@ u32 arch_timer_get_rate(void) return arch_timer_rate; } -/* - * Some external users of arch_timer_read_counter (e.g. sched_clock) may try to - * call it before it has been initialised. Rather than incur a performance - * penalty checking for initialisation, provide a default implementation that - * won't lead to time appearing to jump backwards. - */ -static u64 arch_timer_read_zero(void) +u64 arch_timer_read_counter(void) { - return 0; + return arch_counter_get_cntvct(); } -u64 (*arch_timer_read_counter)(void) = arch_timer_read_zero; - static cycle_t arch_counter_read(struct clocksource *cs) { - return arch_timer_read_counter(); + return arch_counter_get_cntvct(); } static cycle_t arch_counter_read_cc(const struct cyclecounter *cc) { - return arch_timer_read_counter(); + return arch_counter_get_cntvct(); } static struct clocksource clocksource_counter = { @@ -287,7 +279,7 @@ static int __init arch_timer_register(void) cyclecounter.mult = clocksource_counter.mult; cyclecounter.shift = clocksource_counter.shift; timecounter_init(&timecounter, &cyclecounter, - arch_counter_get_cntpct()); + arch_counter_get_cntvct()); if (arch_timer_use_virtual) { ppi = arch_timer_ppi[VIRT_PPI]; @@ -376,11 +368,6 @@ static void __init arch_timer_init(struct device_node *np) } } - if (arch_timer_use_virtual) - arch_timer_read_counter = arch_counter_get_cntvct; - else - arch_timer_read_counter = arch_counter_get_cntpct; - arch_timer_register(); arch_timer_arch_init(); } -- cgit v1.2.3 From 8c37bb3ac95b8ff953bd3c8bc8dd0a393d5ae989 Mon Sep 17 00:00:00 2001 From: Paul Gortmaker Date: Wed, 19 Jun 2013 11:32:08 -0400 Subject: clocksource+irqchip: delete __cpuinit usage from all related files The __cpuinit type of throwaway sections might have made sense some time ago when RAM was more constrained, but now the savings do not offset the cost and complications. For example, the fix in commit 5e427ec2d0 ("x86: Fix bit corruption at CPU resume time") is a good example of the nasty type of bugs that can be created with improper use of the various __init prefixes. After a discussion on LKML[1] it was decided that cpuinit should go the way of devinit and be phased out. Once all the users are gone, we can then finally remove the macros themselves from linux/init.h. This removes all the drivers/clocksource and drivers/irqchip uses of the __cpuinit macros from all C files. [1] https://lkml.org/lkml/2013/5/20/589 Cc: John Stultz Cc: Thomas Gleixner Acked-by: Thomas Gleixner Signed-off-by: Paul Gortmaker --- drivers/clocksource/arm_arch_timer.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) (limited to 'drivers/clocksource/arm_arch_timer.c') diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c index 053d846ab5b1..ffadd836e0b5 100644 --- a/drivers/clocksource/arm_arch_timer.c +++ b/drivers/clocksource/arm_arch_timer.c @@ -123,7 +123,7 @@ static int arch_timer_set_next_event_phys(unsigned long evt, return 0; } -static int __cpuinit arch_timer_setup(struct clock_event_device *clk) +static int arch_timer_setup(struct clock_event_device *clk) { clk->features = CLOCK_EVT_FEAT_ONESHOT | CLOCK_EVT_FEAT_C3STOP; clk->name = "arch_sys_timer"; @@ -221,7 +221,7 @@ struct timecounter *arch_timer_get_timecounter(void) return &timecounter; } -static void __cpuinit arch_timer_stop(struct clock_event_device *clk) +static void arch_timer_stop(struct clock_event_device *clk) { pr_debug("arch_timer_teardown disable IRQ%d cpu #%d\n", clk->irq, smp_processor_id()); @@ -237,7 +237,7 @@ static void __cpuinit arch_timer_stop(struct clock_event_device *clk) clk->set_mode(CLOCK_EVT_MODE_UNUSED, clk); } -static int __cpuinit arch_timer_cpu_notify(struct notifier_block *self, +static int arch_timer_cpu_notify(struct notifier_block *self, unsigned long action, void *hcpu) { /* @@ -256,7 +256,7 @@ static int __cpuinit arch_timer_cpu_notify(struct notifier_block *self, return NOTIFY_OK; } -static struct notifier_block arch_timer_cpu_nb __cpuinitdata = { +static struct notifier_block arch_timer_cpu_nb = { .notifier_call = arch_timer_cpu_notify, }; -- cgit v1.2.3