From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:51542) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bpAz9-0002lQ-Gt for qemu-devel@nongnu.org; Wed, 28 Sep 2016 05:17:04 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bpAz8-0004mu-5s for qemu-devel@nongnu.org; Wed, 28 Sep 2016 05:17:03 -0400 From: P J P Date: Wed, 28 Sep 2016 14:46:48 +0530 Message-Id: <1475054208-20288-1-git-send-email-ppandit@redhat.com> Subject: [Qemu-devel] [PATCH v2] timer: a9gtimer: check auto-increment register value List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Qemu Developers Cc: Peter Maydell , Li Qiang , qemu-arm , Prasad J Pandit From: Prasad J Pandit ARM A9MP processor has a peripheral timer with an auto-increment register, which holds an increment step value. A user could set this value to zero, when auto-increment control bit is enabled. This leads to an infinite loop in 'a9_gtimer_update' while updating comparator value. Remove the loop incrementing the comparator value; Add check to avoid value zero. Reported-by: Li Qiang Signed-off-by: Prasad J Pandit --- hw/timer/a9gtimer.c | 22 ++++++++++------------ 1 file changed, 10 insertions(+), 12 deletions(-) Update per -> https://lists.gnu.org/archive/html/qemu-devel/2016-09/msg05682.html diff --git a/hw/timer/a9gtimer.c b/hw/timer/a9gtimer.c index 772f85f..021ae59 100644 --- a/hw/timer/a9gtimer.c +++ b/hw/timer/a9gtimer.c @@ -72,7 +72,7 @@ static void a9_gtimer_update(A9GTimerState *s, bool sync) { A9GTimerUpdate update = a9_gtimer_get_update(s); - int i; + uint32_t i, inc; int64_t next_cdiff = 0; for (i = 0; i < s->num_cpu; ++i) { @@ -82,16 +82,14 @@ static void a9_gtimer_update(A9GTimerState *s, bool sync) if ((s->control & R_CONTROL_TIMER_ENABLE) && (gtb->control & R_CONTROL_COMP_ENABLE)) { /* R2p0+, where the compare function is >= */ - while (gtb->compare < update.new) { - DB_PRINT("Compare event happened for CPU %d\n", i); - gtb->status = 1; - if (gtb->control & R_CONTROL_AUTO_INCREMENT) { - DB_PRINT("Auto incrementing timer compare by %" PRId32 "\n", - gtb->inc); - gtb->compare += gtb->inc; - } else { - break; - } + DB_PRINT("Compare event happened for CPU %d\n", i); + gtb->status = 1; + if (gtb->control & R_CONTROL_AUTO_INCREMENT + && gtb->compare < update.new) { + inc = ((update.new - gtb->compare - 1) / gtb->inc) * gtb->inc; + DB_PRINT("Auto incrementing timer compare by %" + PRId32 "\n", inc); + gtb->compare += inc; } cdiff = (int64_t)gtb->compare - (int64_t)update.new + 1; if (cdiff > 0 && (cdiff < next_cdiff || !next_cdiff)) { @@ -210,7 +208,7 @@ static void a9_gtimer_write(void *opaque, hwaddr addr, uint64_t value, gtb->compare = deposit64(gtb->compare, shift, 32, value); break; case R_AUTO_INCREMENT: - gtb->inc = value; + gtb->inc = value ? value : 1; return; default: return; -- 2.5.5