On Mon, Jul 06, 2020 at 05:38:00PM +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 express exactly that.

Cc: stable@vger.kernel.org Signed-off-by: Marc Zyngier maz@kernel.org

Acked-by: Mark Rutland mark.rutland@arm.com

Mark.

---

arch/arm64/include/asm/arch_timer.h | 1 + drivers/clocksource/arm_arch_timer.c | 3 +++ 2 files changed, 4 insertions(+)

diff --git a/arch/arm64/include/asm/arch_timer.h b/arch/arm64/include/asm/arch_timer.h index 7ae54d7d333a..9f0ec21d6327 100644 --- 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 ecf7b7db2d05..a8e4fb429f52 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 if (wa->disable_compat_vdso && vdso_default != VDSO_CLOCKMODE_NONE) {

• vdso_default = VDSO_CLOCKMODE_ARCHTIMER_NOCOMPAT;
  

• clocksource_counter.vdso_clock_mode = vdso_default;
  

  }

} -- 2.27.0