Function trap

freebsd/mips/mips/trap.c:510–1121

* Handle an exception. * Called from MipsKernGenException() or MipsUserGenException() * when a processor trap occurs. * In the case of a kernel trap, we return the pc where to resume if * p->p_addr->u_pcb.pcb_onfault is set, otherwise, return old pc. */

 * p->p_addr->u_pcb.pcb_onfault is set, otherwise, return old pc.
 */
register_t
trap(struct trapframe *trapframe)
{
	int type, usermode;
	int i = 0;
	unsigned ucode = 0;
	struct thread *td = curthread;
	struct proc *p = curproc;
	vm_prot_t ftype;
	pmap_t pmap;
	int access_type;
	ksiginfo_t ksi;
	char *msg = NULL;
	intptr_t addr = 0;
	register_t pc;
	int cop, error;
	register_t *frame_regs;
#ifdef KDB
	bool handled;
#endif

	trapdebug_enter(trapframe, 0);
#ifdef KDB
	if (kdb_active) {
		kdb_reenter();
		return (0);
	}
#endif
	type = (trapframe->cause & MIPS_CR_EXC_CODE) >> MIPS_CR_EXC_CODE_SHIFT;
	if (TRAPF_USERMODE(trapframe)) {
		type |= T_USER;
		usermode = 1;
	} else {
		usermode = 0;
	}

	/*
	 * Enable hardware interrupts if they were on before the trap. If it
	 * was off disable all so we don't accidently enable it when doing a
	 * return to userland.
	 */
	if (trapframe->sr & MIPS_SR_INT_IE) {
		set_intr_mask(trapframe->sr & MIPS_SR_INT_MASK);
		intr_enable();
	} else {
		intr_disable();
	}

#ifdef TRAP_DEBUG
	if (trap_debug) {
		static vm_offset_t last_badvaddr = 0;
		static vm_offset_t this_badvaddr = 0;
		static int count = 0;
		u_int32_t pid;

		printf("trap type %x (%s - ", type,
		    trap_type[type & (~T_USER)]);