3.16.7-ckt4 -stable review patch.  If anyone has any objections, please let me 
know.

------------------

From: Nathan Lynch <[email protected]>

commit 423bd69e69f565167ba14e2fe61df76c3c4a0d26 upstream.

The arm and arm64 VDSOs need CP15 access to the architected counter.
If this is unavailable (which is allowed by ARM v7), indicate this by
changing the clocksource name to "arch_mem_counter" before registering
the clocksource.

Suggested by Stephen Boyd.

Signed-off-by: Nathan Lynch <[email protected]>
Reviewed-by: Stephen Boyd <[email protected]>
Signed-off-by: Daniel Lezcano <[email protected]>
Acked-by: Will Deacon <[email protected]>
Signed-off-by: Luis Henriques <[email protected]>
---
 drivers/clocksource/arm_arch_timer.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/drivers/clocksource/arm_arch_timer.c 
b/drivers/clocksource/arm_arch_timer.c
index 5163ec13429d..c99afdf12e98 100644
--- a/drivers/clocksource/arm_arch_timer.c
+++ b/drivers/clocksource/arm_arch_timer.c
@@ -429,11 +429,19 @@ static void __init arch_counter_register(unsigned type)
        u64 start_count;
 
        /* Register the CP15 based counter if we have one */
-       if (type & ARCH_CP15_TIMER)
+       if (type & ARCH_CP15_TIMER) {
                arch_timer_read_counter = arch_counter_get_cntvct;
-       else
+       } else {
                arch_timer_read_counter = arch_counter_get_cntvct_mem;
 
+               /* If the clocksource name is "arch_sys_counter" the
+                * VDSO will attempt to read the CP15-based counter.
+                * Ensure this does not happen when CP15-based
+                * counter is not available.
+                */
+               clocksource_counter.name = "arch_mem_counter";
+       }
+
        start_count = arch_timer_read_counter();
        clocksource_register_hz(&clocksource_counter, arch_timer_rate);
        cyclecounter.mult = clocksource_counter.mult;
-- 
2.1.4

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

Reply via email to