On Wed, 19 Jun 2019, at 02:24, Cédric Le Goater wrote:
> From: Christian Svensson <[email protected]>
>
> 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 <[email protected]>
> Signed-off-by: Cédric Le Goater <[email protected]>
Reviewed-by: Andrew Jeffery <[email protected]>
> ---
> hw/timer/aspeed_timer.c | 6 +++++-
> 1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/hw/timer/aspeed_timer.c b/hw/timer/aspeed_timer.c
> index 6501fa0768e7..1f0f1886fb2a 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;
> --
> 2.21.0
>
>
