[ Upstream commit 8b7770b877d187bfdae1eaf587bd2b792479a31c ]
ARM virtual counter supports event stream, it can only trigger an event
when the trigger bit (the value of CNTKCTL_EL1.EVNTI) of CNTVCT_EL0 changes,
so the actual period of event stream is 2^(cntkctl_evnti + 1). For example,
when the trigger bit is 0, then virtual counter trigger an event for every
two cycles.
While we're at it, rework the way we compute the trigger bit position
by making it more obvious that when bits [n:n-1] are both set (with n
being the most significant bit), we pick bit (n + 1).
Fixes: 037f637767a8 ("drivers: clocksource: add support for ARM architected timer event stream")
Suggested-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Keqian Zhu <zhukeqian1@huawei.com>
Acked-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/20201204073126.6920-3-zhukeqian1@huawei.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit d8cc3905b8073c7cfbff94af889fa8dc71f21dd5 ]
In commit 0ea415390cd3 ("clocksource/arm_arch_timer: Use arch_timer_read_counter
to access stable counters"), we separate stable and normal count reader to omit
unnecessary overhead on systems that have no timer erratum.
However, in erratum_set_next_event_tval_generic(), count reader becomes normal
reader. This converts it to stable reader.
Fixes: 0ea415390cd3 ("clocksource/arm_arch_timer: Use arch_timer_read_counter to access stable counters")
Acked-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Keqian Zhu <zhukeqian1@huawei.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/20201204073126.6920-2-zhukeqian1@huawei.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
commit 4b661d6133c5d3a7c9aca0b4ee5a78c7766eff3f upstream.
ARM64_WORKAROUND_1418040 requires that AArch32 EL0 accesses to
the virtual counter register are trapped and emulated by the kernel.
This makes the vdso pretty pointless, and in some cases livelock
prone.
Provide a workaround entry that limits the vdso to 64bit tasks.
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/20200706163802.1836732-4-maz@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit c1fbec4ac0d701f350a581941d35643d5a9cd184 upstream.
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>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 97884ca8c2925d14c32188e865069f21378b4b4f upstream.
[this is a redesign rather than a backport]
We have a class of errata (grouped under the ARM64_WORKAROUND_1418040
banner) that force the trapping of counter access from 32bit EL0.
We would normally disable the whole vdso for such defect, except that
it would disable it for 64bit userspace as well, which is a shame.
Instead, add a new vdso_clock_mode, which signals that the vdso
isn't usable for compat tasks. This gets checked in the new
vdso_clocksource_ok() helper, now provided for the 32bit vdso.
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/20200706163802.1836732-2-maz@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Keqian Zhu