syscalls: fchdir, setitimer, getitimer

kernel-src/sys/itimer.c

@@ -0,0 +1,88 @@
+#include <kernel/itimer.h>
+#include <logging.h>
+
+static void itimer_dpc(context_t *context, dpcarg_t arg) {
+	itimer_t *itimer = arg;
+	spinlock_acquire(&itimer->lock);
+	if (itimer->paused)
+		goto leave;
+	
+	itimer->remainingus = itimer->repeatus ? itimer->repeatus : 0;
+	itimer->paused = itimer->repeatus == 0;
+	itimer->fn(context, itimer->arg);
+	if (itimer->repeatus) {
+		timer_insert(_cpu()->timer, &itimer->entry, itimer_dpc, itimer, itimer->remainingus, false);
+	}
+
+	leave:
+	spinlock_release(&itimer->lock);
+}
+
+void itimer_init(itimer_t *itimer, dpcfn_t fn, dpcarg_t arg) {
+	memset(itimer, 0, sizeof(itimer_t));
+	itimer->fn = fn;
+	itimer->arg = arg;
+	itimer->paused = true;
+	SPINLOCK_INIT(itimer->lock);
+}
+
+void itimer_pause(itimer_t *itimer, uintmax_t *remainingus, uintmax_t *repeatus) {
+	bool intstatus = interrupt_set(false);
+	spinlock_acquire(&itimer->lock);
+
+	while (itimer->cpu && itimer->cpu != _cpu()) {
+		// schedule on the itimer cpu
+		sched_targetcpu(itimer->cpu);
+		spinlock_release(&itimer->lock);
+		sched_yield();
+		sched_targetcpu(NULL);
+		spinlock_acquire(&itimer->lock);
+	}
+
+	if (itimer->paused)
+		goto cleanup;
+
+	itimer->cpu = NULL;
+	itimer->remainingus = timer_remove(_cpu()->timer, &itimer->entry);
+	if (itimer->remainingus == 0) {
+		// while we were running in the cpu, the timer fired.
+		// the dpc won't be handled because the timer entry
+		// has already been removed from the queue.
+		// this will be handled as a ''timer was one microsecond away from firing''
+		// situation as its the cleanest way of doing this.
+		itimer->remainingus = 1;
+	}
+	itimer->paused = true;
+	cleanup:
+
+	spinlock_release(&itimer->lock);
+	interrupt_set(intstatus);
+	if (remainingus)
+		*remainingus = itimer->remainingus;
+	if (repeatus)
+		*repeatus = itimer->repeatus;
+}
+
+void itimer_set(itimer_t *itimer, uintmax_t timerus, uintmax_t repeatus) {
+	bool intstatus = interrupt_set(false);
+	spinlock_acquire(&itimer->lock);
+
+	itimer->remainingus = timerus;
+	itimer->repeatus = repeatus;
+
+	spinlock_release(&itimer->lock);
+	interrupt_set(intstatus);
+}
+
+void itimer_resume(itimer_t *itimer) {
+	bool intstatus = interrupt_set(false);
+	spinlock_acquire(&itimer->lock);
+
+	__assert(itimer->paused && itimer->remainingus);
+	itimer->cpu = _cpu();
+	itimer->paused = false;
+	timer_insert(_cpu()->timer, &itimer->entry, itimer_dpc, itimer, itimer->remainingus, false);
+
+	spinlock_release(&itimer->lock);
+	interrupt_set(intstatus);
+}