From 055762479be1575377ecf2d8fceb9d8df2703d0f Mon Sep 17 00:00:00 2001 From: Christian Svensson Date: Mon, 1 Jul 2019 17:26:17 +0100 Subject: [PATCH] aspeed/timer: Ensure positive muldiv delta MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 Signed-off-by: Cédric Le Goater Reviewed-by: Joel Stanley Reviewed-by: Andrew Jeffery Message-id: 20190618165311.27066-12-clg@kaod.org Signed-off-by: Peter Maydell --- 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 745eb8608b..29cc5e8070 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;