diff options
| author | Mark Rutland <mark.rutland@arm.com> | 2013-01-30 17:51:26 +0000 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2014-01-09 12:24:26 -0800 |
| commit | 714c21cb90951905b269870087a99c37f3a7af0c (patch) | |
| tree | 8f8ed0735431802c266bcfefabcb97477924f6a1 /arch | |
| parent | ae5092fadd50cfd0d29e762771d30cbf7f2c2fec (diff) | |
clocksource: arch_timer: use virtual counters
commit 0d651e4e65e96989f72236bf83bd4c6e55eb6ce4 upstream.
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 <mark.rutland@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Acked-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Cc: Rob Herring <rob.herring@calxeda.com>
Cc: Mark Brown <broonie@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/arm/include/asm/arch_timer.h | 9 | ||||
| -rw-r--r-- | arch/arm64/include/asm/arch_timer.h | 10 |
2 files changed, 0 insertions, 19 deletions
diff --git a/arch/arm/include/asm/arch_timer.h b/arch/arm/include/asm/arch_timer.h index 7c1bfc0aea0..accefe09918 100644 --- a/arch/arm/include/asm/arch_timer.h +++ b/arch/arm/include/asm/arch_timer.h @@ -80,15 +80,6 @@ static inline u32 arch_timer_get_cntfrq(void) return val; } -static inline u64 arch_counter_get_cntpct(void) -{ - u64 cval; - - isb(); - asm volatile("mrrc p15, 0, %Q0, %R0, c14" : "=r" (cval)); - return cval; -} - static inline u64 arch_counter_get_cntvct(void) { u64 cval; diff --git a/arch/arm64/include/asm/arch_timer.h b/arch/arm64/include/asm/arch_timer.h index bf6ab242f04..d56ed11ba9a 100644 --- a/arch/arm64/include/asm/arch_timer.h +++ b/arch/arm64/include/asm/arch_timer.h @@ -110,16 +110,6 @@ static inline void __cpuinit arch_counter_set_user_access(void) asm volatile("msr cntkctl_el1, %0" : : "r" (cntkctl)); } -static inline u64 arch_counter_get_cntpct(void) -{ - u64 cval; - - isb(); - asm volatile("mrs %0, cntpct_el0" : "=r" (cval)); - - return cval; -} - static inline u64 arch_counter_get_cntvct(void) { u64 cval; |