Function kdb_trap

freebsd/kern/subr_kdb.c:681–751

* Enter the debugger due to a trap. */

 * Enter the debugger due to a trap.
 */
int
kdb_trap(int type, int code, struct trapframe *tf)
{
#ifdef SMP
	cpuset_t other_cpus;
#endif
	struct kdb_dbbe *be;
	register_t intr;
	int handled;
	int did_stop_cpus;

	be = kdb_dbbe;
	if (be == NULL || be->dbbe_trap == NULL)
		return (0);

	/* We reenter the debugger through kdb_reenter(). */
	if (kdb_active)
		return (0);

	intr = intr_disable();

	if (!SCHEDULER_STOPPED()) {
#ifdef SMP
		other_cpus = all_cpus;
		CPU_ANDNOT(&other_cpus, &stopped_cpus);
		CPU_CLR(PCPU_GET(cpuid), &other_cpus);
		stop_cpus_hard(other_cpus);
#endif
		curthread->td_stopsched = 1;
		did_stop_cpus = 1;
	} else
		did_stop_cpus = 0;

	kdb_active++;

	kdb_frame = tf;

	/* Let MD code do its thing first... */
	kdb_cpu_trap(type, code);

	makectx(tf, &kdb_pcb);
	kdb_thr_select(curthread);

	cngrab();

	for (;;) {
		handled = be->dbbe_trap(type, code);
		if (be == kdb_dbbe)
			break;
		be = kdb_dbbe;
		if (be == NULL || be->dbbe_trap == NULL)
			break;
		printf("Switching to %s back-end\n", be->dbbe_name);
	}

	cnungrab();

	kdb_active--;