Messages in this thread | | | Date | Thu, 02 Jul 2020 14:52:25 +0100 | From | Marc Zyngier <> | Subject | Re: [PATCH 2/3] arm64: arch_timer: Allow an workaround descriptor to provide vdso_clock_mode |
| |
On 2020-07-02 11:28, Mark Rutland wrote: > On Wed, Jul 01, 2020 at 05:18:23PM +0100, Marc Zyngier wrote: >> As we are about to disable the vdso for compat tasks in some >> circumstances, >> let's allow a workaround descriptor to provide the vdso_clock_mode >> that >> matches the platform. >> >> Signed-off-by: Marc Zyngier <maz@kernel.org> >> --- >> arch/arm64/include/asm/arch_timer.h | 3 +++ >> drivers/clocksource/arm_arch_timer.c | 3 +++ >> 2 files changed, 6 insertions(+) >> >> diff --git a/arch/arm64/include/asm/arch_timer.h >> b/arch/arm64/include/asm/arch_timer.h >> index 7ae54d7d333a..fb8dfcbf9c01 100644 >> --- a/arch/arm64/include/asm/arch_timer.h >> +++ b/arch/arm64/include/asm/arch_timer.h >> @@ -18,6 +18,8 @@ >> #include <linux/smp.h> >> #include <linux/types.h> >> >> +#include <vdso/clocksource.h> >> + >> #include <clocksource/arm_arch_timer.h> >> >> #if IS_ENABLED(CONFIG_ARM_ARCH_TIMER_OOL_WORKAROUND) >> @@ -58,6 +60,7 @@ struct arch_timer_erratum_workaround { >> u64 (*read_cntvct_el0)(void); >> int (*set_next_event_phys)(unsigned long, struct clock_event_device >> *); >> int (*set_next_event_virt)(unsigned long, struct clock_event_device >> *); >> + enum vdso_clock_mode vdso_clock_mode; >> }; >> >> DECLARE_PER_CPU(const struct arch_timer_erratum_workaround *, >> diff --git a/drivers/clocksource/arm_arch_timer.c >> b/drivers/clocksource/arm_arch_timer.c >> index ecf7b7db2d05..f828835c568f 100644 >> --- a/drivers/clocksource/arm_arch_timer.c >> +++ b/drivers/clocksource/arm_arch_timer.c >> @@ -566,6 +566,9 @@ void arch_timer_enable_workaround(const struct >> arch_timer_erratum_workaround *wa >> if (wa->read_cntvct_el0) { >> clocksource_counter.vdso_clock_mode = VDSO_CLOCKMODE_NONE; >> vdso_default = VDSO_CLOCKMODE_NONE; >> + } else { >> + clocksource_counter.vdso_clock_mode = wa->vdso_clock_mode; >> + vdso_default = wa->vdso_clock_mode; >> } > > I fear that we're liable to forget to set vdso_clock_mode on new errata > that don't need a read_cntvct_el0 hook, and if so we'll happen to set > these to 0 (i.e. VDSO_CLOCKMODE_NONE). > > For now could we instead have a boolan disable_compat_vdso, with this > being: > > | if (wa->read_cntvct_el0) { > | clocksource_counter.vdso_clock_mode = VDSO_CLOCKMODE_NONE; > | vdso_default = VDSO_CLOCKMODE_NONE; > | } else if (wa->disable_compat_vdso) { > | clocksource_counter.vdso_clock_mode = > VDSO_CLOCKMODE_ARCHTIMER_NOCOMPAT; > | vdso_default = wa->vdso_clock_mode = > VDSO_CLOCKMODE_ARCHTIMER_NOCOMPAT; > | }
Sure, that'd work too.
> Do we need to handle the comination of a workaround seeting NONE and > one > setting ARCHTIMER_NOCOMPAT?
Not yet. Probably coming any time now. Which is why we may need to look into per-CPU vdso data pages (Broonie has a series that could be of some use, apparently).
Thanks,
M. -- Jazz is not dead. It just smells funny...
| |