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[PATCH v1 2/2] target/arm: only set the nexttick timer if !ISTATUS
From: |
Alex Bennée |
Subject: |
[PATCH v1 2/2] target/arm: only set the nexttick timer if !ISTATUS |
Date: |
Tue, 28 Jul 2020 15:10:05 +0100 |
Otherwise we have an unfortunate interaction with -count sleep=off
which means we fast forward time when we don't need to. The easiest
way to trigger it was to attach to the gdbstub and place a break point
at the timers IRQ routine. Once the timer fired setting the next event
at INT_MAX then qemu_start_warp_timer would skip to the end.
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
---
target/arm/helper.c | 35 ++++++++++++++++++++++-------------
1 file changed, 22 insertions(+), 13 deletions(-)
diff --git a/target/arm/helper.c b/target/arm/helper.c
index c69a2baf1d3..ec1b84cf0fd 100644
--- a/target/arm/helper.c
+++ b/target/arm/helper.c
@@ -2683,7 +2683,7 @@ static void gt_recalc_timer(ARMCPU *cpu, int timeridx)
uint64_t count = gt_get_countervalue(&cpu->env);
/* Note that this must be unsigned 64 bit arithmetic: */
int istatus = count - offset >= gt->cval;
- uint64_t nexttick;
+ uint64_t nexttick = 0;
int irqstate;
gt->ctl = deposit32(gt->ctl, 2, 1, istatus);
@@ -2692,21 +2692,30 @@ static void gt_recalc_timer(ARMCPU *cpu, int timeridx)
qemu_set_irq(cpu->gt_timer_outputs[timeridx], irqstate);
if (istatus) {
- /* Next transition is when count rolls back over to zero */
- nexttick = UINT64_MAX;
+ /*
+ * The IRQ status of the timer will persist until:
+ * - CVAL is changed or
+ * - ENABLE is changed
+ *
+ * There is no point re-arming the timer for some far
+ * flung future - currently it just is.
+ */
+ timer_del(cpu->gt_timer[timeridx]);
} else {
/* Next transition is when we hit cval */
nexttick = gt->cval + offset;
- }
- /* Note that the desired next expiry time might be beyond the
- * signed-64-bit range of a QEMUTimer -- in this case we just
- * set the timer for as far in the future as possible. When the
- * timer expires we will reset the timer for any remaining period.
- */
- if (nexttick > INT64_MAX / gt_cntfrq_period_ns(cpu)) {
- timer_mod_ns(cpu->gt_timer[timeridx], INT64_MAX);
- } else {
- timer_mod(cpu->gt_timer[timeridx], nexttick);
+
+ /*
+ * It is possible the next tick is beyond the
+ * signed-64-bit range of a QEMUTimer but currently the
+ * timer system doesn't support a run time of more the 292
+ * odd years so we set it to INT_MAX in this case.
+ */
+ if (nexttick > INT64_MAX / gt_cntfrq_period_ns(cpu)) {
+ timer_mod_ns(cpu->gt_timer[timeridx], INT64_MAX);
+ } else {
+ timer_mod(cpu->gt_timer[timeridx], nexttick);
+ }
}
trace_arm_gt_recalc(timeridx, irqstate, nexttick);
} else {
--
2.20.1