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aspeed/timer: Ensure positive muldiv delta

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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>
Reviewed-by: Joel Stanley <joel@jms.id.au>
Reviewed-by: Andrew Jeffery <andrew@aj.id.au>
Message-id: 20190618165311.27066-12-clg@kaod.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
This commit is contained in:
Christian Svensson 2019-07-01 17:26:17 +01:00 committed by Peter Maydell
parent 696942b8bc
commit 055762479b
1 changed files with 5 additions and 1 deletions
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6
hw/timer/aspeed_timer.c
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@ -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;