If gt_timer is enabled before cval initialization on a virtualized
setup on QEMU, cval equals (UINT64_MAX - 1). Adding an offset value
to this causes an overflow that sets timer into the past, which leads
to infinite loop, because this timer fires immediately and calls
gt_recalc_timer() once more, which in turn sets the timer into the
past again and as a result, QEMU hangs. This patch adds check for
overflowing of the nexttick variable.
Suggested-by: Volodymyr Babchuk <volodymyr_babc...@epam.com>
Co-Authored-By: Dmytro Firsov <dmytro_fir...@epam.com>
Signed-off-by: Leonid Komarianskyi <leonid_komarians...@epam.com>
---
target/arm/helper.c | 10 ++++++++++
1 file changed, 10 insertions(+)
diff --git a/target/arm/helper.c b/target/arm/helper.c
index 3b22596eab..b4aaa2965b 100644
--- a/target/arm/helper.c
+++ b/target/arm/helper.c
@@ -2665,6 +2665,16 @@ static void gt_recalc_timer(ARMCPU *cpu, int timeridx)
} else {
/* Next transition is when we hit cval */
nexttick = gt->cval + offset;
+ if (nexttick < gt->cval) {
+ /*
+ * If gt->cval value is close to UINT64_MAX then adding
+ * to it offset can lead to overflow of nexttick variable.
+ * So, this check tests that arguments sum is less than any
+ * addend, and in case it is overflowed we have to mod timer
+ * to INT64_MAX.
+ */
+ nexttick = UINT64_MAX;
+ }
}
/*
* Note that the desired next expiry time might be beyond the
--
2.25.1
