diff mbox series

[12/19] aspeed/timer: Ensure positive muldiv delta

Message ID 20190525151241.5017-13-clg@kaod.org
State New
Headers show
Series aspeed: machine extensions and fixes | expand

Commit Message

Cédric Le Goater May 25, 2019, 3:12 p.m. UTC 
From: Christian Svensson <bluecmd@google.com>

If the host decrements the counter register that results in a negative
delta. This is then passed to muldiv64 which only handles unsigned
numbers resulting in bogus results.

This fix ensures the delta being operated on is positive.

Test case: kexec a kernel using aspeed_timer and it will freeze on the
second bootup when the kernel initializes the timer. With this patch
that no longer happens and the timer appears to run OK.

Signed-off-by: Christian Svensson <bluecmd@google.com>
Signed-off-by: Cédric Le Goater <clg@kaod.org>
---
 hw/timer/aspeed_timer.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)
diff mbox series

Patch

diff --git a/hw/timer/aspeed_timer.c b/hw/timer/aspeed_timer.c
index 9988b8fbbf17..53b70f859c86 100644
--- a/hw/timer/aspeed_timer.c
+++ b/hw/timer/aspeed_timer.c
@@ -275,7 +275,11 @@  static void aspeed_timer_set_value(AspeedTimerCtrlState *s, int timer, int reg,
             int64_t delta = (int64_t) value - (int64_t) calculate_ticks(t, now);
             uint32_t rate = calculate_rate(t);
 
-            t->start += muldiv64(delta, NANOSECONDS_PER_SECOND, rate);
+            if (delta >= 0) {
+                t->start += muldiv64(delta, NANOSECONDS_PER_SECOND, rate);
+            } else {
+                t->start -= muldiv64(-delta, NANOSECONDS_PER_SECOND, rate);
+            }
             aspeed_timer_mod(t);
         }
         break;