Exemplo n.º 1
0
void
trap(struct trapframe *frame)
{
	struct thread *td = curthread;
	struct proc *p = td->td_proc;
	int i = 0, ucode = 0, code;
	u_int type;
	register_t addr = 0;
	vm_offset_t eva;
	ksiginfo_t ksi;
#ifdef POWERFAIL_NMI
	static int lastalert = 0;
#endif

	PCPU_INC(cnt.v_trap);
	type = frame->tf_trapno;

#ifdef SMP
	/* Handler for NMI IPIs used for stopping CPUs. */
	if (type == T_NMI) {
	         if (ipi_nmi_handler() == 0)
	                   goto out;
	}
#endif /* SMP */

#ifdef KDB
	if (kdb_active) {
		kdb_reenter();
		goto out;
	}
#endif

	if (type == T_RESERVED) {
		trap_fatal(frame, 0);
		goto out;
	}

#ifdef	HWPMC_HOOKS
	/*
	 * CPU PMCs interrupt using an NMI so we check for that first.
	 * If the HWPMC module is active, 'pmc_hook' will point to
	 * the function to be called.  A return value of '1' from the
	 * hook means that the NMI was handled by it and that we can
	 * return immediately.
	 */
	if (type == T_NMI && pmc_intr &&
	    (*pmc_intr)(PCPU_GET(cpuid), frame))
	    goto out;
#endif

	if (type == T_MCHK) {
		mca_intr();
		goto out;
	}

#ifdef KDTRACE_HOOKS
	/*
	 * A trap can occur while DTrace executes a probe. Before
	 * executing the probe, DTrace blocks re-scheduling and sets
	 * a flag in it's per-cpu flags to indicate that it doesn't
	 * want to fault. On returning from the probe, the no-fault
	 * flag is cleared and finally re-scheduling is enabled.
	 *
	 * If the DTrace kernel module has registered a trap handler,
	 * call it and if it returns non-zero, assume that it has
	 * handled the trap and modified the trap frame so that this
	 * function can return normally.
	 */
	if (type == T_DTRACE_PROBE || type == T_DTRACE_RET ||
	    type == T_BPTFLT) {
		struct reg regs;

		fill_frame_regs(frame, &regs);
		if (type == T_DTRACE_PROBE &&
		    dtrace_fasttrap_probe_ptr != NULL &&
		    dtrace_fasttrap_probe_ptr(&regs) == 0)
			goto out;
		if (type == T_BPTFLT &&
		    dtrace_pid_probe_ptr != NULL &&
		    dtrace_pid_probe_ptr(&regs) == 0)
			goto out;
		if (type == T_DTRACE_RET &&
		    dtrace_return_probe_ptr != NULL &&
		    dtrace_return_probe_ptr(&regs) == 0)
			goto out;
	}
	if ((type == T_PROTFLT || type == T_PAGEFLT) &&
	    dtrace_trap_func != NULL && (*dtrace_trap_func)(frame, type))
		goto out;
#endif

	if ((frame->tf_eflags & PSL_I) == 0) {
		/*
		 * Buggy application or kernel code has disabled
		 * interrupts and then trapped.  Enabling interrupts
		 * now is wrong, but it is better than running with
		 * interrupts disabled until they are accidentally
		 * enabled later.
		 */
		if (ISPL(frame->tf_cs) == SEL_UPL || (frame->tf_eflags & PSL_VM))
			uprintf(
			    "pid %ld (%s): trap %d with interrupts disabled\n",
			    (long)curproc->p_pid, curthread->td_name, type);
		else if (type != T_NMI && type != T_BPTFLT &&
		    type != T_TRCTRAP &&
		    frame->tf_eip != (int)cpu_switch_load_gs) {
			/*
			 * XXX not quite right, since this may be for a
			 * multiple fault in user mode.
			 */
			printf("kernel trap %d with interrupts disabled\n",
			    type);
			/*
			 * Page faults need interrupts disabled until later,
			 * and we shouldn't enable interrupts while holding
			 * a spin lock.
			 */
			if (type != T_PAGEFLT &&
			    td->td_md.md_spinlock_count == 0)
				enable_intr();
		}
	}
	eva = 0;
	code = frame->tf_err;
	if (type == T_PAGEFLT) {
		/*
		 * For some Cyrix CPUs, %cr2 is clobbered by
		 * interrupts.  This problem is worked around by using
		 * an interrupt gate for the pagefault handler.  We
		 * are finally ready to read %cr2 and conditionally
		 * reenable interrupts.  If we hold a spin lock, then
		 * we must not reenable interrupts.  This might be a
		 * spurious page fault.
		 */
		eva = rcr2();
		if (td->td_md.md_spinlock_count == 0)
			enable_intr();
	}

        if ((ISPL(frame->tf_cs) == SEL_UPL) ||
	    ((frame->tf_eflags & PSL_VM) && 
		!(curpcb->pcb_flags & PCB_VM86CALL))) {
		/* user trap */

		td->td_pticks = 0;
		td->td_frame = frame;
		addr = frame->tf_eip;
		if (td->td_ucred != p->p_ucred) 
			cred_update_thread(td);

		switch (type) {
		case T_PRIVINFLT:	/* privileged instruction fault */
			i = SIGILL;
			ucode = ILL_PRVOPC;
			break;

		case T_BPTFLT:		/* bpt instruction fault */
		case T_TRCTRAP:		/* trace trap */
			enable_intr();
			frame->tf_eflags &= ~PSL_T;
			i = SIGTRAP;
			ucode = (type == T_TRCTRAP ? TRAP_TRACE : TRAP_BRKPT);
			break;

		case T_ARITHTRAP:	/* arithmetic trap */
#ifdef DEV_NPX
			ucode = npxtrap_x87();
			if (ucode == -1)
				goto userout;
#else
			ucode = 0;
#endif
			i = SIGFPE;
			break;

			/*
			 * The following two traps can happen in
			 * vm86 mode, and, if so, we want to handle
			 * them specially.
			 */
		case T_PROTFLT:		/* general protection fault */
		case T_STKFLT:		/* stack fault */
			if (frame->tf_eflags & PSL_VM) {
				i = vm86_emulate((struct vm86frame *)frame);
				if (i == 0)
					goto user;
				break;
			}
			i = SIGBUS;
			ucode = (type == T_PROTFLT) ? BUS_OBJERR : BUS_ADRERR;
			break;
		case T_SEGNPFLT:	/* segment not present fault */
			i = SIGBUS;
			ucode = BUS_ADRERR;
			break;
		case T_TSSFLT:		/* invalid TSS fault */
			i = SIGBUS;
			ucode = BUS_OBJERR;
			break;
		case T_DOUBLEFLT:	/* double fault */
		default:
			i = SIGBUS;
			ucode = BUS_OBJERR;
			break;

		case T_PAGEFLT:		/* page fault */

			i = trap_pfault(frame, TRUE, eva);
#if defined(I586_CPU) && !defined(NO_F00F_HACK)
			if (i == -2) {
				/*
				 * The f00f hack workaround has triggered, so
				 * treat the fault as an illegal instruction 
				 * (T_PRIVINFLT) instead of a page fault.
				 */
				type = frame->tf_trapno = T_PRIVINFLT;

				/* Proceed as in that case. */
				ucode = ILL_PRVOPC;
				i = SIGILL;
				break;
			}
#endif
			if (i == -1)
				goto userout;
			if (i == 0)
				goto user;

			if (i == SIGSEGV)
				ucode = SEGV_MAPERR;
			else {
				if (prot_fault_translation == 0) {
					/*
					 * Autodetect.
					 * This check also covers the images
					 * without the ABI-tag ELF note.
					 */
					if (SV_CURPROC_ABI() == SV_ABI_FREEBSD
					    && p->p_osrel >= P_OSREL_SIGSEGV) {
						i = SIGSEGV;
						ucode = SEGV_ACCERR;
					} else {
						i = SIGBUS;
						ucode = BUS_PAGE_FAULT;
					}
				} else if (prot_fault_translation == 1) {
					/*
					 * Always compat mode.
					 */
					i = SIGBUS;
					ucode = BUS_PAGE_FAULT;
				} else {
					/*
					 * Always SIGSEGV mode.
					 */
					i = SIGSEGV;
					ucode = SEGV_ACCERR;
				}
			}
			addr = eva;
			break;

		case T_DIVIDE:		/* integer divide fault */
			ucode = FPE_INTDIV;
			i = SIGFPE;
			break;

#ifdef DEV_ISA
		case T_NMI:
#ifdef POWERFAIL_NMI
#ifndef TIMER_FREQ
#  define TIMER_FREQ 1193182
#endif
			if (time_second - lastalert > 10) {
				log(LOG_WARNING, "NMI: power fail\n");
				sysbeep(880, hz);
				lastalert = time_second;
			}
			goto userout;
#else /* !POWERFAIL_NMI */
			/* machine/parity/power fail/"kitchen sink" faults */
			if (isa_nmi(code) == 0) {
#ifdef KDB
				/*
				 * NMI can be hooked up to a pushbutton
				 * for debugging.
				 */
				if (kdb_on_nmi) {
					printf ("NMI ... going to debugger\n");
					kdb_trap(type, 0, frame);
				}
#endif /* KDB */
				goto userout;
			} else if (panic_on_nmi)
				panic("NMI indicates hardware failure");
			break;
#endif /* POWERFAIL_NMI */
#endif /* DEV_ISA */

		case T_OFLOW:		/* integer overflow fault */
			ucode = FPE_INTOVF;
			i = SIGFPE;
			break;

		case T_BOUND:		/* bounds check fault */
			ucode = FPE_FLTSUB;
			i = SIGFPE;
			break;

		case T_DNA:
#ifdef DEV_NPX
			KASSERT(PCB_USER_FPU(td->td_pcb),
			    ("kernel FPU ctx has leaked"));
			/* transparent fault (due to context switch "late") */
			if (npxdna())
				goto userout;
#endif
			uprintf("pid %d killed due to lack of floating point\n",
				p->p_pid);
			i = SIGKILL;
			ucode = 0;
			break;

		case T_FPOPFLT:		/* FPU operand fetch fault */
			ucode = ILL_COPROC;
			i = SIGILL;
			break;

		case T_XMMFLT:		/* SIMD floating-point exception */
#if defined(DEV_NPX) && !defined(CPU_DISABLE_SSE) && defined(I686_CPU)
			ucode = npxtrap_sse();
			if (ucode == -1)
				goto userout;
#else
			ucode = 0;
#endif
			i = SIGFPE;
			break;
		}
	} else {
		/* kernel trap */

		KASSERT(cold || td->td_ucred != NULL,
		    ("kernel trap doesn't have ucred"));
		switch (type) {
		case T_PAGEFLT:			/* page fault */
			(void) trap_pfault(frame, FALSE, eva);
			goto out;

		case T_DNA:
#ifdef DEV_NPX
			KASSERT(!PCB_USER_FPU(td->td_pcb),
			    ("Unregistered use of FPU in kernel"));
			if (npxdna())
				goto out;
#endif
			break;

		case T_ARITHTRAP:	/* arithmetic trap */
		case T_XMMFLT:		/* SIMD floating-point exception */
		case T_FPOPFLT:		/* FPU operand fetch fault */
			/*
			 * XXXKIB for now disable any FPU traps in kernel
			 * handler registration seems to be overkill
			 */
			trap_fatal(frame, 0);
			goto out;

			/*
			 * The following two traps can happen in
			 * vm86 mode, and, if so, we want to handle
			 * them specially.
			 */
		case T_PROTFLT:		/* general protection fault */
		case T_STKFLT:		/* stack fault */
			if (frame->tf_eflags & PSL_VM) {
				i = vm86_emulate((struct vm86frame *)frame);
				if (i != 0)
					/*
					 * returns to original process
					 */
					vm86_trap((struct vm86frame *)frame);
				goto out;
			}
			if (type == T_STKFLT)
				break;

			/* FALL THROUGH */

		case T_SEGNPFLT:	/* segment not present fault */
			if (curpcb->pcb_flags & PCB_VM86CALL)
				break;

			/*
			 * Invalid %fs's and %gs's can be created using
			 * procfs or PT_SETREGS or by invalidating the
			 * underlying LDT entry.  This causes a fault
			 * in kernel mode when the kernel attempts to
			 * switch contexts.  Lose the bad context
			 * (XXX) so that we can continue, and generate
			 * a signal.
			 */
			if (frame->tf_eip == (int)cpu_switch_load_gs) {
				curpcb->pcb_gs = 0;
#if 0				
				PROC_LOCK(p);
				kern_psignal(p, SIGBUS);
				PROC_UNLOCK(p);
#endif				
				goto out;
			}

			if (td->td_intr_nesting_level != 0)
				break;

			/*
			 * Invalid segment selectors and out of bounds
			 * %eip's and %esp's can be set up in user mode.
			 * This causes a fault in kernel mode when the
			 * kernel tries to return to user mode.  We want
			 * to get this fault so that we can fix the
			 * problem here and not have to check all the
			 * selectors and pointers when the user changes
			 * them.
			 */
			if (frame->tf_eip == (int)doreti_iret) {
				frame->tf_eip = (int)doreti_iret_fault;
				goto out;
			}
			if (frame->tf_eip == (int)doreti_popl_ds) {
				frame->tf_eip = (int)doreti_popl_ds_fault;
				goto out;
			}
			if (frame->tf_eip == (int)doreti_popl_es) {
				frame->tf_eip = (int)doreti_popl_es_fault;
				goto out;
			}
			if (frame->tf_eip == (int)doreti_popl_fs) {
				frame->tf_eip = (int)doreti_popl_fs_fault;
				goto out;
			}
			if (curpcb->pcb_onfault != NULL) {
				frame->tf_eip =
				    (int)curpcb->pcb_onfault;
				goto out;
			}
			break;

		case T_TSSFLT:
			/*
			 * PSL_NT can be set in user mode and isn't cleared
			 * automatically when the kernel is entered.  This
			 * causes a TSS fault when the kernel attempts to
			 * `iret' because the TSS link is uninitialized.  We
			 * want to get this fault so that we can fix the
			 * problem here and not every time the kernel is
			 * entered.
			 */
			if (frame->tf_eflags & PSL_NT) {
				frame->tf_eflags &= ~PSL_NT;
				goto out;
			}
			break;

		case T_TRCTRAP:	 /* trace trap */
			if (frame->tf_eip == (int)IDTVEC(lcall_syscall)) {
				/*
				 * We've just entered system mode via the
				 * syscall lcall.  Continue single stepping
				 * silently until the syscall handler has
				 * saved the flags.
				 */
				goto out;
			}
			if (frame->tf_eip == (int)IDTVEC(lcall_syscall) + 1) {
				/*
				 * The syscall handler has now saved the
				 * flags.  Stop single stepping it.
				 */
				frame->tf_eflags &= ~PSL_T;
				goto out;
			}
			/*
			 * Ignore debug register trace traps due to
			 * accesses in the user's address space, which
			 * can happen under several conditions such as
			 * if a user sets a watchpoint on a buffer and
			 * then passes that buffer to a system call.
			 * We still want to get TRCTRAPS for addresses
			 * in kernel space because that is useful when
			 * debugging the kernel.
			 */
			if (user_dbreg_trap() && 
			   !(curpcb->pcb_flags & PCB_VM86CALL)) {
				/*
				 * Reset breakpoint bits because the
				 * processor doesn't
				 */
				load_dr6(rdr6() & 0xfffffff0);
				goto out;
			}
			/*
			 * FALLTHROUGH (TRCTRAP kernel mode, kernel address)
			 */
		case T_BPTFLT:
			/*
			 * If KDB is enabled, let it handle the debugger trap.
			 * Otherwise, debugger traps "can't happen".
			 */
#ifdef KDB
			if (kdb_trap(type, 0, frame))
				goto out;
#endif
			break;

#ifdef DEV_ISA
		case T_NMI:
#ifdef POWERFAIL_NMI
			if (time_second - lastalert > 10) {
				log(LOG_WARNING, "NMI: power fail\n");
				sysbeep(880, hz);
				lastalert = time_second;
			}
			goto out;
#else /* !POWERFAIL_NMI */
			/* machine/parity/power fail/"kitchen sink" faults */
			if (isa_nmi(code) == 0) {
#ifdef KDB
				/*
				 * NMI can be hooked up to a pushbutton
				 * for debugging.
				 */
				if (kdb_on_nmi) {
					printf ("NMI ... going to debugger\n");
					kdb_trap(type, 0, frame);
				}
#endif /* KDB */
				goto out;
			} else if (panic_on_nmi == 0)
				goto out;
			/* FALLTHROUGH */
#endif /* POWERFAIL_NMI */
#endif /* DEV_ISA */
		}

		trap_fatal(frame, eva);
		goto out;
	}

	/* Translate fault for emulators (e.g. Linux) */
	if (*p->p_sysent->sv_transtrap)
		i = (*p->p_sysent->sv_transtrap)(i, type);

	ksiginfo_init_trap(&ksi);
	ksi.ksi_signo = i;
	ksi.ksi_code = ucode;
	ksi.ksi_addr = (void *)addr;
	ksi.ksi_trapno = type;
	if (uprintf_signal) {
		uprintf("pid %d comm %s: signal %d err %x code %d type %d "
		    "addr 0x%x esp 0x%08x eip 0x%08x "
		    "<%02x %02x %02x %02x %02x %02x %02x %02x>\n",
		    p->p_pid, p->p_comm, i, frame->tf_err, ucode, type, addr,
		    frame->tf_esp, frame->tf_eip,
		    fubyte((void *)(frame->tf_eip + 0)),
		    fubyte((void *)(frame->tf_eip + 1)),
		    fubyte((void *)(frame->tf_eip + 2)),
		    fubyte((void *)(frame->tf_eip + 3)),
		    fubyte((void *)(frame->tf_eip + 4)),
		    fubyte((void *)(frame->tf_eip + 5)),
		    fubyte((void *)(frame->tf_eip + 6)),
		    fubyte((void *)(frame->tf_eip + 7)));
	}
	KASSERT((read_eflags() & PSL_I) != 0, ("interrupts disabled"));
	trapsignal(td, &ksi);

#ifdef DEBUG
	if (type <= MAX_TRAP_MSG) {
		uprintf("fatal process exception: %s",
			trap_msg[type]);
		if ((type == T_PAGEFLT) || (type == T_PROTFLT))
			uprintf(", fault VA = 0x%lx", (u_long)eva);
		uprintf("\n");
	}
#endif

user:
	userret(td, frame);
	KASSERT(PCB_USER_FPU(td->td_pcb),
	    ("Return from trap with kernel FPU ctx leaked"));
userout:
out:
	return;
}
Exemplo n.º 2
0
void
trap(struct trapframe *frame)
{
#ifdef KDTRACE_HOOKS
	struct reg regs;
#endif
	struct thread *td = curthread;
	struct proc *p = td->td_proc;
	int i = 0, ucode = 0, code;
	u_int type;
	register_t addr = 0;
	ksiginfo_t ksi;

	PCPU_INC(cnt.v_trap);
	type = frame->tf_trapno;

#ifdef SMP
	/* Handler for NMI IPIs used for stopping CPUs. */
	if (type == T_NMI) {
	         if (ipi_nmi_handler() == 0)
	                   goto out;
	}
#endif /* SMP */

#ifdef KDB
	if (kdb_active) {
		kdb_reenter();
		goto out;
	}
#endif

	if (type == T_RESERVED) {
		trap_fatal(frame, 0);
		goto out;
	}

#ifdef	HWPMC_HOOKS
	/*
	 * CPU PMCs interrupt using an NMI.  If the PMC module is
	 * active, pass the 'rip' value to the PMC module's interrupt
	 * handler.  A return value of '1' from the handler means that
	 * the NMI was handled by it and we can return immediately.
	 */
	if (type == T_NMI && pmc_intr &&
	    (*pmc_intr)(PCPU_GET(cpuid), frame))
		goto out;
#endif

	if (type == T_MCHK) {
		mca_intr();
		goto out;
	}

#ifdef KDTRACE_HOOKS
	/*
	 * A trap can occur while DTrace executes a probe. Before
	 * executing the probe, DTrace blocks re-scheduling and sets
	 * a flag in its per-cpu flags to indicate that it doesn't
	 * want to fault. On returning from the probe, the no-fault
	 * flag is cleared and finally re-scheduling is enabled.
	 */
	if (dtrace_trap_func != NULL && (*dtrace_trap_func)(frame, type))
		goto out;
#endif

	if ((frame->tf_rflags & PSL_I) == 0) {
		/*
		 * Buggy application or kernel code has disabled
		 * interrupts and then trapped.  Enabling interrupts
		 * now is wrong, but it is better than running with
		 * interrupts disabled until they are accidentally
		 * enabled later.
		 */
		if (ISPL(frame->tf_cs) == SEL_UPL)
			uprintf(
			    "pid %ld (%s): trap %d with interrupts disabled\n",
			    (long)curproc->p_pid, curthread->td_name, type);
		else if (type != T_NMI && type != T_BPTFLT &&
		    type != T_TRCTRAP) {
			/*
			 * XXX not quite right, since this may be for a
			 * multiple fault in user mode.
			 */
			printf("kernel trap %d with interrupts disabled\n",
			    type);

			/*
			 * We shouldn't enable interrupts while holding a
			 * spin lock.
			 */
			if (td->td_md.md_spinlock_count == 0)
				enable_intr();
		}
	}

	code = frame->tf_err;

        if (ISPL(frame->tf_cs) == SEL_UPL) {
		/* user trap */

		td->td_pticks = 0;
		td->td_frame = frame;
		addr = frame->tf_rip;
		if (td->td_ucred != p->p_ucred) 
			cred_update_thread(td);

		switch (type) {
		case T_PRIVINFLT:	/* privileged instruction fault */
			i = SIGILL;
			ucode = ILL_PRVOPC;
			break;

		case T_BPTFLT:		/* bpt instruction fault */
		case T_TRCTRAP:		/* trace trap */
			enable_intr();
#ifdef KDTRACE_HOOKS
			if (type == T_BPTFLT) {
				fill_frame_regs(frame, &regs);
				if (dtrace_pid_probe_ptr != NULL &&
				    dtrace_pid_probe_ptr(&regs) == 0)
					goto out;
			}
#endif
			frame->tf_rflags &= ~PSL_T;
			i = SIGTRAP;
			ucode = (type == T_TRCTRAP ? TRAP_TRACE : TRAP_BRKPT);
			break;

		case T_ARITHTRAP:	/* arithmetic trap */
			ucode = fputrap_x87();
			if (ucode == -1)
				goto userout;
			i = SIGFPE;
			break;

		case T_PROTFLT:		/* general protection fault */
			i = SIGBUS;
			ucode = BUS_OBJERR;
			break;
		case T_STKFLT:		/* stack fault */
		case T_SEGNPFLT:	/* segment not present fault */
			i = SIGBUS;
			ucode = BUS_ADRERR;
			break;
		case T_TSSFLT:		/* invalid TSS fault */
			i = SIGBUS;
			ucode = BUS_OBJERR;
			break;
		case T_ALIGNFLT:
			i = SIGBUS;
			ucode = BUS_ADRALN;
			break;
		case T_DOUBLEFLT:	/* double fault */
		default:
			i = SIGBUS;
			ucode = BUS_OBJERR;
			break;

		case T_PAGEFLT:		/* page fault */
			addr = frame->tf_addr;
			i = trap_pfault(frame, TRUE);
			if (i == -1)
				goto userout;
			if (i == 0)
				goto user;

			if (i == SIGSEGV)
				ucode = SEGV_MAPERR;
			else {
				if (prot_fault_translation == 0) {
					/*
					 * Autodetect.
					 * This check also covers the images
					 * without the ABI-tag ELF note.
					 */
					if (SV_CURPROC_ABI() == SV_ABI_FREEBSD
					    && p->p_osrel >= P_OSREL_SIGSEGV) {
						i = SIGSEGV;
						ucode = SEGV_ACCERR;
					} else {
						i = SIGBUS;
						ucode = BUS_PAGE_FAULT;
					}
				} else if (prot_fault_translation == 1) {
					/*
					 * Always compat mode.
					 */
					i = SIGBUS;
					ucode = BUS_PAGE_FAULT;
				} else {
					/*
					 * Always SIGSEGV mode.
					 */
					i = SIGSEGV;
					ucode = SEGV_ACCERR;
				}
			}
			break;

		case T_DIVIDE:		/* integer divide fault */
			ucode = FPE_INTDIV;
			i = SIGFPE;
			break;

#ifdef DEV_ISA
		case T_NMI:
			/* machine/parity/power fail/"kitchen sink" faults */
			if (isa_nmi(code) == 0) {
#ifdef KDB
				/*
				 * NMI can be hooked up to a pushbutton
				 * for debugging.
				 */
				if (kdb_on_nmi) {
					printf ("NMI ... going to debugger\n");
					kdb_trap(type, 0, frame);
				}
#endif /* KDB */
				goto userout;
			} else if (panic_on_nmi)
				panic("NMI indicates hardware failure");
			break;
#endif /* DEV_ISA */

		case T_OFLOW:		/* integer overflow fault */
			ucode = FPE_INTOVF;
			i = SIGFPE;
			break;

		case T_BOUND:		/* bounds check fault */
			ucode = FPE_FLTSUB;
			i = SIGFPE;
			break;

		case T_DNA:
			/* transparent fault (due to context switch "late") */
			KASSERT(PCB_USER_FPU(td->td_pcb),
			    ("kernel FPU ctx has leaked"));
			fpudna();
			goto userout;

		case T_FPOPFLT:		/* FPU operand fetch fault */
			ucode = ILL_COPROC;
			i = SIGILL;
			break;

		case T_XMMFLT:		/* SIMD floating-point exception */
			ucode = fputrap_sse();
			if (ucode == -1)
				goto userout;
			i = SIGFPE;
			break;
#ifdef KDTRACE_HOOKS
		case T_DTRACE_RET:
			enable_intr();
			fill_frame_regs(frame, &regs);
			if (dtrace_return_probe_ptr != NULL &&
			    dtrace_return_probe_ptr(&regs) == 0)
				goto out;
			break;
#endif
		}
	} else {
		/* kernel trap */

		KASSERT(cold || td->td_ucred != NULL,
		    ("kernel trap doesn't have ucred"));
		switch (type) {
		case T_PAGEFLT:			/* page fault */
			(void) trap_pfault(frame, FALSE);
			goto out;

		case T_DNA:
			KASSERT(!PCB_USER_FPU(td->td_pcb),
			    ("Unregistered use of FPU in kernel"));
			fpudna();
			goto out;

		case T_ARITHTRAP:	/* arithmetic trap */
		case T_XMMFLT:		/* SIMD floating-point exception */
		case T_FPOPFLT:		/* FPU operand fetch fault */
			/*
			 * For now, supporting kernel handler
			 * registration for FPU traps is overkill.
			 */
			trap_fatal(frame, 0);
			goto out;

		case T_STKFLT:		/* stack fault */
		case T_PROTFLT:		/* general protection fault */
		case T_SEGNPFLT:	/* segment not present fault */
			if (td->td_intr_nesting_level != 0)
				break;

			/*
			 * Invalid segment selectors and out of bounds
			 * %rip's and %rsp's can be set up in user mode.
			 * This causes a fault in kernel mode when the
			 * kernel tries to return to user mode.  We want
			 * to get this fault so that we can fix the
			 * problem here and not have to check all the
			 * selectors and pointers when the user changes
			 * them.
			 */
			if (frame->tf_rip == (long)doreti_iret) {
				frame->tf_rip = (long)doreti_iret_fault;
				goto out;
			}
			if (frame->tf_rip == (long)ld_ds) {
				frame->tf_rip = (long)ds_load_fault;
				goto out;
			}
			if (frame->tf_rip == (long)ld_es) {
				frame->tf_rip = (long)es_load_fault;
				goto out;
			}
			if (frame->tf_rip == (long)ld_fs) {
				frame->tf_rip = (long)fs_load_fault;
				goto out;
			}
			if (frame->tf_rip == (long)ld_gs) {
				frame->tf_rip = (long)gs_load_fault;
				goto out;
			}
			if (frame->tf_rip == (long)ld_gsbase) {
				frame->tf_rip = (long)gsbase_load_fault;
				goto out;
			}
			if (frame->tf_rip == (long)ld_fsbase) {
				frame->tf_rip = (long)fsbase_load_fault;
				goto out;
			}
			if (curpcb->pcb_onfault != NULL) {
				frame->tf_rip = (long)curpcb->pcb_onfault;
				goto out;
			}
			break;

		case T_TSSFLT:
			/*
			 * PSL_NT can be set in user mode and isn't cleared
			 * automatically when the kernel is entered.  This
			 * causes a TSS fault when the kernel attempts to
			 * `iret' because the TSS link is uninitialized.  We
			 * want to get this fault so that we can fix the
			 * problem here and not every time the kernel is
			 * entered.
			 */
			if (frame->tf_rflags & PSL_NT) {
				frame->tf_rflags &= ~PSL_NT;
				goto out;
			}
			break;

		case T_TRCTRAP:	 /* trace trap */
			/*
			 * Ignore debug register trace traps due to
			 * accesses in the user's address space, which
			 * can happen under several conditions such as
			 * if a user sets a watchpoint on a buffer and
			 * then passes that buffer to a system call.
			 * We still want to get TRCTRAPS for addresses
			 * in kernel space because that is useful when
			 * debugging the kernel.
			 */
			if (user_dbreg_trap()) {
				/*
				 * Reset breakpoint bits because the
				 * processor doesn't
				 */
				/* XXX check upper bits here */
				load_dr6(rdr6() & 0xfffffff0);
				goto out;
			}
			/*
			 * FALLTHROUGH (TRCTRAP kernel mode, kernel address)
			 */
		case T_BPTFLT:
			/*
			 * If KDB is enabled, let it handle the debugger trap.
			 * Otherwise, debugger traps "can't happen".
			 */
#ifdef KDB
			if (kdb_trap(type, 0, frame))
				goto out;
#endif
			break;

#ifdef DEV_ISA
		case T_NMI:
			/* machine/parity/power fail/"kitchen sink" faults */
			if (isa_nmi(code) == 0) {
#ifdef KDB
				/*
				 * NMI can be hooked up to a pushbutton
				 * for debugging.
				 */
				if (kdb_on_nmi) {
					printf ("NMI ... going to debugger\n");
					kdb_trap(type, 0, frame);
				}
#endif /* KDB */
				goto out;
			} else if (panic_on_nmi == 0)
				goto out;
			/* FALLTHROUGH */
#endif /* DEV_ISA */
		}

		trap_fatal(frame, 0);
		goto out;
	}

	/* Translate fault for emulators (e.g. Linux) */
	if (*p->p_sysent->sv_transtrap)
		i = (*p->p_sysent->sv_transtrap)(i, type);

	ksiginfo_init_trap(&ksi);
	ksi.ksi_signo = i;
	ksi.ksi_code = ucode;
	ksi.ksi_trapno = type;
	ksi.ksi_addr = (void *)addr;
	if (uprintf_signal) {
		uprintf("pid %d comm %s: signal %d err %lx code %d type %d "
		    "addr 0x%lx rsp 0x%lx rip 0x%lx "
		    "<%02x %02x %02x %02x %02x %02x %02x %02x>\n",
		    p->p_pid, p->p_comm, i, frame->tf_err, ucode, type, addr,
		    frame->tf_rsp, frame->tf_rip,
		    fubyte((void *)(frame->tf_rip + 0)),
		    fubyte((void *)(frame->tf_rip + 1)),
		    fubyte((void *)(frame->tf_rip + 2)),
		    fubyte((void *)(frame->tf_rip + 3)),
		    fubyte((void *)(frame->tf_rip + 4)),
		    fubyte((void *)(frame->tf_rip + 5)),
		    fubyte((void *)(frame->tf_rip + 6)),
		    fubyte((void *)(frame->tf_rip + 7)));
	}
	KASSERT((read_rflags() & PSL_I) != 0, ("interrupts disabled"));
	trapsignal(td, &ksi);

user:
	userret(td, frame);
	KASSERT(PCB_USER_FPU(td->td_pcb),
	    ("Return from trap with kernel FPU ctx leaked"));
userout:
out:
	return;
}