arm64: arch_timer: Allow an workaround descriptor to disable compat vdso

As we are about to disable the vdso for compat tasks in some circumstances,
let's allow a workaround descriptor to express exactly that.

Signed-off-by: Marc Zyngier <maz@kernel.org>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20200706163802.1836732-3-maz@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>

diff --git a/arch/arm64/include/asm/arch_timer.h b/arch/arm64/include/asm/arch_timer.h
index 7ae54d7..9f0ec21 100644 (file)
--- a/arch/arm64/include/asm/arch_timer.h
+++ b/arch/arm64/include/asm/arch_timer.h
@@ -58,6 +58,7 @@ 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 *);
+       bool disable_compat_vdso;
 };
 
 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 ecf7b7d..a8e4fb4 100644 (file)
--- 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 if (wa->disable_compat_vdso && vdso_default != VDSO_CLOCKMODE_NONE) {
+               vdso_default = VDSO_CLOCKMODE_ARCHTIMER_NOCOMPAT;
+               clocksource_counter.vdso_clock_mode = vdso_default;
        }
 }