| Message ID | 20200701161824.1346732-3-maz@kernel.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | arm64: Allow the compat vdso to be disabled at runtime | expand |
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; | } Do we need to handle the comination of a workaround seeting NONE and one setting ARCHTIMER_NOCOMPAT? Mark.
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.
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; } }
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(+)