[PATCH 15/16] clocksource/arm_arch_timer: Add helper to disable VDSO fastpath

From: Marc Zyngier
Date: Fri Jul 21 2017 - 13:16:25 EST


As we are going to add more paths where we have to disable the
counter access in the VDSO, let's add a helper that does exactly that.

Acked-by: Mark Rutland <mark.rutland@xxxxxxx>
Signed-off-by: Marc Zyngier <marc.zyngier@xxxxxxx>
---
drivers/clocksource/arm_arch_timer.c | 28 ++++++++++++++++++----------
1 file changed, 18 insertions(+), 10 deletions(-)

diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c
index aae87c4c546e..4f4633157978 100644
--- a/drivers/clocksource/arm_arch_timer.c
+++ b/drivers/clocksource/arm_arch_timer.c
@@ -188,6 +188,22 @@ struct ate_acpi_oem_info {
u32 oem_revision;
};

+static void __maybe_unused disable_vdso(void)
+{
+ /*
+ * Don't use the vdso fastpath if errata require using the
+ * out-of-line counter accessor and/or trap its access. We may
+ * change our mind pretty late in the game (with a per-CPU
+ * erratum, for example), so change both the default value and
+ * the vdso itself.
+ */
+ if (vdso_default) {
+ pr_info("Disabling VDSO direct access\n");
+ clocksource_counter.archdata.vdso_direct = false;
+ vdso_default = false;
+ }
+}
+
#ifdef CONFIG_FSL_ERRATUM_A008585
/*
* The number of retries is an arbitrary value well beyond the highest number
@@ -457,16 +473,8 @@ void arch_timer_enable_workaround(const struct arch_timer_erratum_workaround *wa

static_branch_enable(&arch_timer_read_ool_enabled);

- /*
- * Don't use the vdso fastpath if errata require using the
- * out-of-line counter accessor. We may change our mind pretty
- * late in the game (with a per-CPU erratum, for example), so
- * change both the default value and the vdso itself.
- */
- if (wa->read_cntvct_el0) {
- clocksource_counter.archdata.vdso_direct = false;
- vdso_default = false;
- }
+ if (wa->read_cntvct_el0)
+ disable_vdso();
}

static void arch_timer_check_ool_workaround(enum arch_timer_erratum_match_type type,
--
2.11.0