aboutsummaryrefslogtreecommitdiff
diff options
context:
space:
mode:
authorAlex Bennée <alex.bennee@linaro.org>2017-04-05 12:32:37 +0100
committerAlex Bennée <alex.bennee@linaro.org>2017-04-10 10:23:38 +0100
commit512d3c807177b5cfff6b5a4925d71ae1b5521093 (patch)
treee28725655ab542d8a7e0c5eab665c009a0ea6727
parente4cd96571f00e290e93dcc65a6d2b616b159dea6 (diff)
cpus: introduce cpu_update_icount helper
By holding off updates to timer_state.qemu_icount we can run into trouble when the non-vCPU thread needs to know the time. This helper ensures we atomically update timers_state.qemu_icount based on what has been currently executed. Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
-rw-r--r--cpus.c23
-rw-r--r--include/qemu/timer.h1
2 files changed, 22 insertions, 2 deletions
diff --git a/cpus.c b/cpus.c
index 0ecb0b87f0..a5125d7167 100644
--- a/cpus.c
+++ b/cpus.c
@@ -232,12 +232,31 @@ static int64_t cpu_get_icount_executed(CPUState *cpu)
return cpu->icount_budget - (cpu->icount_decr.u16.low + cpu->icount_extra);
}
+/*
+ * Update the global shared timer_state.qemu_icount to take into
+ * account executed instructions. This is done by the TCG vCPU
+ * thread so the main-loop can see time has moved forward.
+ */
+void cpu_update_icount(CPUState *cpu)
+{
+ int64_t executed = cpu_get_icount_executed(cpu);
+ cpu->icount_budget -= executed;
+
+#ifdef CONFIG_ATOMIC64
+ atomic_set__nocheck(&timers_state.qemu_icount,
+ atomic_read__nocheck(&timers_state.qemu_icount) +
+ executed);
+#else /* FIXME: we need 64bit atomics to do this safely */
+ timers_state.qemu_icount += executed;
+#endif
+}
+
int64_t cpu_get_icount_raw(void)
{
int64_t icount;
CPUState *cpu = current_cpu;
- icount = timers_state.qemu_icount;
+ icount = atomic_read(&timers_state.qemu_icount);
if (cpu && cpu->running) {
if (!cpu->can_do_io) {
fprintf(stderr, "Bad icount read\n");
@@ -1220,7 +1239,7 @@ static void process_icount_data(CPUState *cpu)
{
if (use_icount) {
/* Account for executed instructions */
- timers_state.qemu_icount += cpu_get_icount_executed(cpu);
+ cpu_update_icount(cpu);
/* Reset the counters */
cpu->icount_decr.u16.low = 0;
diff --git a/include/qemu/timer.h b/include/qemu/timer.h
index e1742f2f3d..8a1eb74839 100644
--- a/include/qemu/timer.h
+++ b/include/qemu/timer.h
@@ -869,6 +869,7 @@ int64_t cpu_get_icount_raw(void);
int64_t cpu_get_icount(void);
int64_t cpu_get_clock(void);
int64_t cpu_icount_to_ns(int64_t icount);
+void cpu_update_icount(CPUState *cpu);
/*******************************************/
/* host CPU ticks (if available) */