xref: /freebsd-10.0-release/sys/mips/mips/vm_machdep.c

/*-
 * Copyright (c) 1982, 1986 The Regents of the University of California.
 * Copyright (c) 1989, 1990 William Jolitz
 * Copyright (c) 1994 John Dyson
 * All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * the Systems Programming Group of the University of Utah Computer
 * Science Department, and William Jolitz.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *	from: @(#)vm_machdep.c	7.3 (Berkeley) 5/13/91
 *	Utah $Hdr: vm_machdep.c 1.16.1.1 89/06/23$
 *	from: src/sys/i386/i386/vm_machdep.c,v 1.132.2.2 2000/08/26 04:19:26 yokota
 *	JNPR: vm_machdep.c,v 1.8.2.2 2007/08/16 15:59:17 girish
 */

#include <sys/cdefs.h>
__FBSDID("$FreeBSD: head/sys/mips/mips/vm_machdep.c 210644 2010-07-30 12:45:00Z jchandra $");

#include "opt_cputype.h"
#include "opt_ddb.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/malloc.h>
#include <sys/proc.h>
#include <sys/syscall.h>
#include <sys/buf.h>
#include <sys/vnode.h>
#include <sys/vmmeter.h>
#include <sys/kernel.h>
#include <sys/sysctl.h>
#include <sys/unistd.h>

#include <machine/asm.h>
#include <machine/cache.h>
#include <machine/clock.h>
#include <machine/cpu.h>
#include <machine/md_var.h>
#include <machine/pcb.h>

#include <vm/vm.h>
#include <vm/vm_extern.h>
#include <vm/pmap.h>
#include <vm/vm_kern.h>
#include <vm/vm_map.h>
#include <vm/vm_page.h>
#include <vm/vm_pageout.h>
#include <vm/vm_param.h>
#include <vm/uma.h>
#include <vm/uma_int.h>

#include <sys/user.h>
#include <sys/mbuf.h>
#include <sys/sf_buf.h>

#ifndef NSFBUFS
#define	NSFBUFS		(512 + maxusers * 16)
#endif

static void	sf_buf_init(void *arg);
SYSINIT(sock_sf, SI_SUB_MBUF, SI_ORDER_ANY, sf_buf_init, NULL);

/*
 * Expanded sf_freelist head.  Really an SLIST_HEAD() in disguise, with the
 * sf_freelist head with the sf_lock mutex.
 */
static struct {
	SLIST_HEAD(, sf_buf) sf_head;
	struct mtx sf_lock;
} sf_freelist;

static u_int	sf_buf_alloc_want;

/*
 * Finish a fork operation, with process p2 nearly set up.
 * Copy and update the pcb, set up the stack so that the child
 * ready to run and return to user mode.
 */
void
cpu_fork(register struct thread *td1,register struct proc *p2,
    struct thread *td2,int flags)
{
	register struct proc *p1;
	struct pcb *pcb2;

	p1 = td1->td_proc;
	if ((flags & RFPROC) == 0)
		return;
	/* It is assumed that the vm_thread_alloc called
	 * cpu_thread_alloc() before cpu_fork is called.
	 */

	/* Point the pcb to the top of the stack */
	pcb2 = td2->td_pcb;

	/* Copy p1's pcb, note that in this case
	 * our pcb also includes the td_frame being copied
	 * too. The older mips2 code did an additional copy
	 * of the td_frame, for us thats not needed any
	 * longer (this copy does them both
	 */
	bcopy(td1->td_pcb, pcb2, sizeof(*pcb2));

	/* Point mdproc and then copy over td1's contents
	 * md_proc is empty for MIPS
	 */
	td2->td_md.md_flags = td1->td_md.md_flags & MDTD_FPUSED;

	/*
	 * Set up return-value registers as fork() libc stub expects.
	 */
	td2->td_frame->v0 = 0;
	td2->td_frame->v1 = 1;
	td2->td_frame->a3 = 0;

	if (td1 == PCPU_GET(fpcurthread))
		MipsSaveCurFPState(td1);

	pcb2->pcb_context[PCB_REG_RA] = (register_t)(intptr_t)fork_trampoline;
	/* Make sp 64-bit aligned */
	pcb2->pcb_context[PCB_REG_SP] = (register_t)(((vm_offset_t)td2->td_pcb &
	    ~(sizeof(__int64_t) - 1)) - CALLFRAME_SIZ);
	pcb2->pcb_context[PCB_REG_S0] = (register_t)(intptr_t)fork_return;
	pcb2->pcb_context[PCB_REG_S1] = (register_t)(intptr_t)td2;
	pcb2->pcb_context[PCB_REG_S2] = (register_t)(intptr_t)td2->td_frame;
	pcb2->pcb_context[PCB_REG_SR] = mips_rd_status() &
	    (MIPS_SR_KX | MIPS_SR_UX | MIPS_SR_INT_MASK);
	/*
	 * FREEBSD_DEVELOPERS_FIXME:
	 * Setup any other CPU-Specific registers (Not MIPS Standard)
	 * and/or bits in other standard MIPS registers (if CPU-Specific)
	 *  that are needed.
	 */

	td2->td_md.md_tls = td1->td_md.md_tls;
	td2->td_md.md_saved_intr = MIPS_SR_INT_IE;
	td2->td_md.md_spinlock_count = 1;
#ifdef CPU_CNMIPS
	pcb2->pcb_context[PCB_REG_SR] |= MIPS_SR_COP_2_BIT | MIPS_SR_PX | MIPS_SR_UX | MIPS_SR_KX | MIPS_SR_SX;
#endif
}

/*
 * Intercept the return address from a freshly forked process that has NOT
 * been scheduled yet.
 *
 * This is needed to make kernel threads stay in kernel mode.
 */
void
cpu_set_fork_handler(struct thread *td, void (*func) __P((void *)), void *arg)
{
	/*
	 * Note that the trap frame follows the args, so the function
	 * is really called like this:	func(arg, frame);
	 */
	td->td_pcb->pcb_context[PCB_REG_S0] = (register_t)(intptr_t)func;
	td->td_pcb->pcb_context[PCB_REG_S1] = (register_t)(intptr_t)arg;
}

void
cpu_exit(struct thread *td)
{
}

void
cpu_thread_exit(struct thread *td)
{

	if (PCPU_GET(fpcurthread) == td)
		PCPU_GET(fpcurthread) = (struct thread *)0;
}

void
cpu_thread_free(struct thread *td)
{
}

void
cpu_thread_clean(struct thread *td)
{
}

void
cpu_thread_swapin(struct thread *td)
{
	pt_entry_t *pte;
	int i;

	/*
	 * The kstack may be at a different physical address now.
	 * Cache the PTEs for the Kernel stack in the machine dependent
	 * part of the thread struct so cpu_switch() can quickly map in
	 * the pcb struct and kernel stack.
	 */
	for (i = 0; i < KSTACK_PAGES; i++) {
		pte = pmap_pte(kernel_pmap, td->td_kstack + i * PAGE_SIZE);
		td->td_md.md_upte[i] = *pte & ~TLBLO_SWBITS_MASK;
	}
}

void
cpu_thread_swapout(struct thread *td)
{
}

void
cpu_thread_alloc(struct thread *td)
{
	pt_entry_t *pte;
	int i;

	KASSERT((td->td_kstack & (1 << PAGE_SHIFT)) == 0, ("kernel stack must be aligned."));
	td->td_pcb = (struct pcb *)(td->td_kstack +
	    td->td_kstack_pages * PAGE_SIZE) - 1;
	td->td_frame = &td->td_pcb->pcb_regs;

	for (i = 0; i < KSTACK_PAGES; i++) {
		pte = pmap_pte(kernel_pmap, td->td_kstack + i * PAGE_SIZE);
		td->td_md.md_upte[i] = *pte & ~TLBLO_SWBITS_MASK;
	}
}

void
cpu_set_syscall_retval(struct thread *td, int error)
{
	struct trapframe *locr0 = td->td_frame;
	unsigned int code;
	int quad_syscall;

	code = locr0->v0;
	quad_syscall = 0;
#if defined(__mips_o32)
	if (code == SYS___syscall)
		quad_syscall = 1;
#endif

	if (code == SYS_syscall)
		code = locr0->a0;
	else if (code == SYS___syscall) {
		if (quad_syscall)
			code = _QUAD_LOWWORD ? locr0->a1 : locr0->a0;
		else
			code = locr0->a0;
	}

	switch (error) {
	case 0:
		if (quad_syscall && code != SYS_lseek) {
			/*
			 * System call invoked through the
			 * SYS___syscall interface but the
			 * return value is really just 32
			 * bits.
			 */
			locr0->v0 = td->td_retval[0];
			if (_QUAD_LOWWORD)
				locr0->v1 = td->td_retval[0];
			locr0->a3 = 0;
		} else {
			locr0->v0 = td->td_retval[0];
			locr0->v1 = td->td_retval[1];
			locr0->a3 = 0;
		}
		break;

	case ERESTART:
		locr0->pc = td->td_pcb->pcb_tpc;
		break;

	case EJUSTRETURN:
		break;	/* nothing to do */

	default:
		if (quad_syscall && code != SYS_lseek) {
			locr0->v0 = error;
			if (_QUAD_LOWWORD)
				locr0->v1 = error;
			locr0->a3 = 1;
		} else {
			locr0->v0 = error;
			locr0->a3 = 1;
		}
	}
}

/*
 * Initialize machine state (pcb and trap frame) for a new thread about to
 * upcall. Put enough state in the new thread's PCB to get it to go back
 * userret(), where we can intercept it again to set the return (upcall)
 * Address and stack, along with those from upcals that are from other sources
 * such as those generated in thread_userret() itself.
 */
void
cpu_set_upcall(struct thread *td, struct thread *td0)
{
	struct pcb *pcb2;

	/* Point the pcb to the top of the stack. */
	pcb2 = td->td_pcb;

	/*
	 * Copy the upcall pcb.  This loads kernel regs.
	 * Those not loaded individually below get their default
	 * values here.
	 *
	 * XXXKSE It might be a good idea to simply skip this as
	 * the values of the other registers may be unimportant.
	 * This would remove any requirement for knowing the KSE
	 * at this time (see the matching comment below for
	 * more analysis) (need a good safe default).
	 * In MIPS, the trapframe is the first element of the PCB
	 * and gets copied when we copy the PCB. No seperate copy
	 * is needed.
	 */
	bcopy(td0->td_pcb, pcb2, sizeof(*pcb2));

	/*
	 * Set registers for trampoline to user mode.
	 */

	pcb2->pcb_context[PCB_REG_RA] = (register_t)(intptr_t)fork_trampoline;
	/* Make sp 64-bit aligned */
	pcb2->pcb_context[PCB_REG_SP] = (register_t)(((vm_offset_t)td->td_pcb &
	    ~(sizeof(__int64_t) - 1)) - CALLFRAME_SIZ);
	pcb2->pcb_context[PCB_REG_S0] = (register_t)(intptr_t)fork_return;
	pcb2->pcb_context[PCB_REG_S1] = (register_t)(intptr_t)td;
	pcb2->pcb_context[PCB_REG_S2] = (register_t)(intptr_t)td->td_frame;
	/* Dont set IE bit in SR. sched lock release will take care of it */
	pcb2->pcb_context[PCB_REG_SR] = mips_rd_status() &
	    (MIPS_SR_KX | MIPS_SR_UX | MIPS_SR_INT_MASK);

#ifdef CPU_CNMIPS
	pcb2->pcb_context[PCB_REG_SR] |= MIPS_SR_COP_2_BIT | MIPS_SR_COP_0_BIT |
	  MIPS_SR_PX | MIPS_SR_UX | MIPS_SR_KX | MIPS_SR_SX;
#endif

	/*
	 * FREEBSD_DEVELOPERS_FIXME:
	 * Setup any other CPU-Specific registers (Not MIPS Standard)
	 * that are needed.
	 */

	/* SMP Setup to release sched_lock in fork_exit(). */
	td->td_md.md_spinlock_count = 1;
	td->td_md.md_saved_intr = MIPS_SR_INT_IE;
#if 0
	    /* Maybe we need to fix this? */
	td->td_md.md_saved_sr = ( (MIPS_SR_COP_2_BIT | MIPS_SR_COP_0_BIT) |
	                          (MIPS_SR_PX | MIPS_SR_UX | MIPS_SR_KX | MIPS_SR_SX) |
	                          (MIPS_SR_INT_IE | MIPS_HARD_INT_MASK));
#endif
}

/*
 * Set that machine state for performing an upcall that has to
 * be done in thread_userret() so that those upcalls generated
 * in thread_userret() itself can be done as well.
 */
void
cpu_set_upcall_kse(struct thread *td, void (*entry)(void *), void *arg,
    stack_t *stack)
{
	struct trapframe *tf;
	register_t sp;

	/*
	* At the point where a function is called, sp must be 8
	* byte aligned[for compatibility with 64-bit CPUs]
	* in ``See MIPS Run'' by D. Sweetman, p. 269
	* align stack */
	sp = ((register_t)(intptr_t)(stack->ss_sp + stack->ss_size) & ~0x7) -
	    CALLFRAME_SIZ;

	/*
	 * Set the trap frame to point at the beginning of the uts
	 * function.
	 */
	tf = td->td_frame;
	bzero(tf, sizeof(struct trapframe));
	tf->sp = sp;
	tf->pc = (register_t)(intptr_t)entry;
	/*
	 * MIPS ABI requires T9 to be the same as PC
	 * in subroutine entry point
	 */
	tf->t9 = (register_t)(intptr_t)entry;
	tf->a0 = (register_t)(intptr_t)arg;

	/*
	 * Keep interrupt mask
	 */
	td->td_frame->sr = MIPS_SR_KSU_USER | MIPS_SR_EXL | MIPS_SR_INT_IE |
	    (mips_rd_status() & MIPS_SR_INT_MASK);
#if defined(__mips_n32)
	td->td_frame->sr |= MIPS_SR_PX;
#elif  defined(__mips_n64)
	td->td_frame->sr |= MIPS_SR_PX | MIPS_SR_UX;
#endif
#ifdef CPU_CNMIPS
	tf->sr |=  MIPS_SR_INT_IE | MIPS_SR_COP_0_BIT | MIPS_SR_PX | MIPS_SR_UX |
	  MIPS_SR_KX;
#endif
/*	tf->sr |= (ALL_INT_MASK & idle_mask) | SR_INT_ENAB; */
	/**XXX the above may now be wrong -- mips2 implements this as panic */
	/*
	 * FREEBSD_DEVELOPERS_FIXME:
	 * Setup any other CPU-Specific registers (Not MIPS Standard)
	 * that are needed.
	 */
}
/*
 * Convert kernel VA to physical address
 */
u_long
kvtop(void *addr)
{
	vm_offset_t va;

	va = pmap_kextract((vm_offset_t)addr);
	if (va == 0)
		panic("kvtop: zero page frame");
	return((intptr_t)va);
}

/*
 * Implement the pre-zeroed page mechanism.
 * This routine is called from the idle loop.
 */

#define	ZIDLE_LO(v)	((v) * 2 / 3)
#define	ZIDLE_HI(v)	((v) * 4 / 5)

/*
 * Allocate a pool of sf_bufs (sendfile(2) or "super-fast" if you prefer. :-))
 */
static void
sf_buf_init(void *arg)
{
	struct sf_buf *sf_bufs;
	vm_offset_t sf_base;
	int i;

	nsfbufs = NSFBUFS;
	TUNABLE_INT_FETCH("kern.ipc.nsfbufs", &nsfbufs);

	mtx_init(&sf_freelist.sf_lock, "sf_bufs list lock", NULL, MTX_DEF);
	SLIST_INIT(&sf_freelist.sf_head);
	sf_base = kmem_alloc_nofault(kernel_map, nsfbufs * PAGE_SIZE);
	sf_bufs = malloc(nsfbufs * sizeof(struct sf_buf), M_TEMP,
	    M_NOWAIT | M_ZERO);
	for (i = 0; i < nsfbufs; i++) {
		sf_bufs[i].kva = sf_base + i * PAGE_SIZE;
		SLIST_INSERT_HEAD(&sf_freelist.sf_head, &sf_bufs[i], free_list);
	}
	sf_buf_alloc_want = 0;
}

/*
 * Get an sf_buf from the freelist.  Will block if none are available.
 */
struct sf_buf *
sf_buf_alloc(struct vm_page *m, int flags)
{
	struct sf_buf *sf;
	int error;

	mtx_lock(&sf_freelist.sf_lock);
	while ((sf = SLIST_FIRST(&sf_freelist.sf_head)) == NULL) {
		if (flags & SFB_NOWAIT)
			break;
		sf_buf_alloc_want++;
		mbstat.sf_allocwait++;
		error = msleep(&sf_freelist, &sf_freelist.sf_lock,
		    (flags & SFB_CATCH) ? PCATCH | PVM : PVM, "sfbufa", 0);
		sf_buf_alloc_want--;

		/*
		 * If we got a signal, don't risk going back to sleep.
		 */
		if (error)
			break;
	}
	if (sf != NULL) {
		SLIST_REMOVE_HEAD(&sf_freelist.sf_head, free_list);
		sf->m = m;
		nsfbufsused++;
		nsfbufspeak = imax(nsfbufspeak, nsfbufsused);
		pmap_qenter(sf->kva, &sf->m, 1);
	}
	mtx_unlock(&sf_freelist.sf_lock);
	return (sf);
}

/*
 * Release resources back to the system.
 */
void
sf_buf_free(struct sf_buf *sf)
{

	pmap_qremove(sf->kva, 1);
	mtx_lock(&sf_freelist.sf_lock);
	SLIST_INSERT_HEAD(&sf_freelist.sf_head, sf, free_list);
	nsfbufsused--;
	if (sf_buf_alloc_want > 0)
		wakeup_one(&sf_freelist);
	mtx_unlock(&sf_freelist.sf_lock);
}

/*
 * Software interrupt handler for queued VM system processing.
 */
void
swi_vm(void *dummy)
{
}

int
cpu_set_user_tls(struct thread *td, void *tls_base)
{

	td->td_md.md_tls = tls_base;
	return (0);
}

#ifdef DDB
#include <ddb/ddb.h>

#define DB_PRINT_REG(ptr, regname)			\
	db_printf("  %-12s %p\n", #regname, (void *)(intptr_t)((ptr)->regname))

#define DB_PRINT_REG_ARRAY(ptr, arrname, regname)	\
	db_printf("  %-12s %p\n", #regname, (void *)(intptr_t)((ptr)->arrname[regname]))

static void
dump_trapframe(struct trapframe *trapframe)
{

	db_printf("Trapframe at %p\n", trapframe);

	DB_PRINT_REG(trapframe, zero);
	DB_PRINT_REG(trapframe, ast);
	DB_PRINT_REG(trapframe, v0);
	DB_PRINT_REG(trapframe, v1);
	DB_PRINT_REG(trapframe, a0);
	DB_PRINT_REG(trapframe, a1);
	DB_PRINT_REG(trapframe, a2);
	DB_PRINT_REG(trapframe, a3);
	DB_PRINT_REG(trapframe, t0);
	DB_PRINT_REG(trapframe, t1);
	DB_PRINT_REG(trapframe, t2);
	DB_PRINT_REG(trapframe, t3);
	DB_PRINT_REG(trapframe, t4);
	DB_PRINT_REG(trapframe, t5);
	DB_PRINT_REG(trapframe, t6);
	DB_PRINT_REG(trapframe, t7);
	DB_PRINT_REG(trapframe, s0);
	DB_PRINT_REG(trapframe, s1);
	DB_PRINT_REG(trapframe, s2);
	DB_PRINT_REG(trapframe, s3);
	DB_PRINT_REG(trapframe, s4);
	DB_PRINT_REG(trapframe, s5);
	DB_PRINT_REG(trapframe, s6);
	DB_PRINT_REG(trapframe, s7);
	DB_PRINT_REG(trapframe, t8);
	DB_PRINT_REG(trapframe, t9);
	DB_PRINT_REG(trapframe, k0);
	DB_PRINT_REG(trapframe, k1);
	DB_PRINT_REG(trapframe, gp);
	DB_PRINT_REG(trapframe, sp);
	DB_PRINT_REG(trapframe, s8);
	DB_PRINT_REG(trapframe, ra);
	DB_PRINT_REG(trapframe, sr);
	DB_PRINT_REG(trapframe, mullo);
	DB_PRINT_REG(trapframe, mulhi);
	DB_PRINT_REG(trapframe, badvaddr);
	DB_PRINT_REG(trapframe, cause);
	DB_PRINT_REG(trapframe, pc);
}

DB_SHOW_COMMAND(pcb, ddb_dump_pcb)
{
	struct thread *td;
	struct pcb *pcb;
	struct trapframe *trapframe;

	/* Determine which thread to examine. */
	if (have_addr)
		td = db_lookup_thread(addr, TRUE);
	else
		td = curthread;

	pcb = td->td_pcb;

	db_printf("Thread %d at %p\n", td->td_tid, td);

	db_printf("PCB at %p\n", pcb);

	trapframe = &pcb->pcb_regs;
	dump_trapframe(trapframe);

	db_printf("PCB Context:\n");
	DB_PRINT_REG_ARRAY(pcb, pcb_context, PCB_REG_S0);
	DB_PRINT_REG_ARRAY(pcb, pcb_context, PCB_REG_S1);
	DB_PRINT_REG_ARRAY(pcb, pcb_context, PCB_REG_S2);
	DB_PRINT_REG_ARRAY(pcb, pcb_context, PCB_REG_S3);
	DB_PRINT_REG_ARRAY(pcb, pcb_context, PCB_REG_S4);
	DB_PRINT_REG_ARRAY(pcb, pcb_context, PCB_REG_S5);
	DB_PRINT_REG_ARRAY(pcb, pcb_context, PCB_REG_S6);
	DB_PRINT_REG_ARRAY(pcb, pcb_context, PCB_REG_S7);
	DB_PRINT_REG_ARRAY(pcb, pcb_context, PCB_REG_SP);
	DB_PRINT_REG_ARRAY(pcb, pcb_context, PCB_REG_S8);
	DB_PRINT_REG_ARRAY(pcb, pcb_context, PCB_REG_RA);
	DB_PRINT_REG_ARRAY(pcb, pcb_context, PCB_REG_SR);
	DB_PRINT_REG_ARRAY(pcb, pcb_context, PCB_REG_GP);
	DB_PRINT_REG_ARRAY(pcb, pcb_context, PCB_REG_PC);

	db_printf("PCB onfault = %p\n", pcb->pcb_onfault);
	db_printf("md_saved_intr = 0x%0lx\n", (long)td->td_md.md_saved_intr);
	db_printf("md_spinlock_count = %d\n", td->td_md.md_spinlock_count);

	if (td->td_frame != trapframe) {
		db_printf("td->td_frame %p is not the same as pcb_regs %p\n",
			  td->td_frame, trapframe);
	}
}

/*
 * Dump the trapframe beginning at address specified by first argument.
 */
DB_SHOW_COMMAND(trapframe, ddb_dump_trapframe)
{

	if (!have_addr)
		return;

	dump_trapframe((struct trapframe *)addr);
}

#endif	/* DDB */