xref: /freebsd-12.1/sys/i386/i386/machdep.c (revision c5ae6cf2)

/*-
 * SPDX-License-Identifier: BSD-4-Clause
 *
 * Copyright (c) 2018 The FreeBSD Foundation
 * Copyright (c) 1992 Terrence R. Lambert.
 * Copyright (c) 1982, 1987, 1990 The Regents of the University of California.
 * All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * William Jolitz.
 *
 * Portions of this software were developed by A. Joseph Koshy under
 * sponsorship from the FreeBSD Foundation and Google, Inc.
 *
 * 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.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 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: @(#)machdep.c	7.4 (Berkeley) 6/3/91
 */

#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");

#include "opt_apic.h"
#include "opt_atpic.h"
#include "opt_cpu.h"
#include "opt_ddb.h"
#include "opt_inet.h"
#include "opt_isa.h"
#include "opt_kstack_pages.h"
#include "opt_maxmem.h"
#include "opt_mp_watchdog.h"
#include "opt_perfmon.h"
#include "opt_platform.h"

#include <sys/param.h>
#include <sys/proc.h>
#include <sys/systm.h>
#include <sys/bio.h>
#include <sys/buf.h>
#include <sys/bus.h>
#include <sys/callout.h>
#include <sys/cons.h>
#include <sys/cpu.h>
#include <sys/eventhandler.h>
#include <sys/exec.h>
#include <sys/imgact.h>
#include <sys/kdb.h>
#include <sys/kernel.h>
#include <sys/ktr.h>
#include <sys/linker.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/memrange.h>
#include <sys/msgbuf.h>
#include <sys/mutex.h>
#include <sys/pcpu.h>
#include <sys/ptrace.h>
#include <sys/reboot.h>
#include <sys/rwlock.h>
#include <sys/sched.h>
#include <sys/signalvar.h>
#include <sys/smp.h>
#include <sys/syscallsubr.h>
#include <sys/sysctl.h>
#include <sys/sysent.h>
#include <sys/sysproto.h>
#include <sys/ucontext.h>
#include <sys/vmmeter.h>

#include <vm/vm.h>
#include <vm/vm_extern.h>
#include <vm/vm_kern.h>
#include <vm/vm_page.h>
#include <vm/vm_map.h>
#include <vm/vm_object.h>
#include <vm/vm_pager.h>
#include <vm/vm_param.h>
#include <vm/vm_phys.h>

#ifdef DDB
#ifndef KDB
#error KDB must be enabled in order for DDB to work!
#endif
#include <ddb/ddb.h>
#include <ddb/db_sym.h>
#endif

#include <isa/rtc.h>

#include <net/netisr.h>

#include <machine/bootinfo.h>
#include <machine/clock.h>
#include <machine/cpu.h>
#include <machine/cputypes.h>
#include <machine/intr_machdep.h>
#include <x86/mca.h>
#include <machine/md_var.h>
#include <machine/metadata.h>
#include <machine/mp_watchdog.h>
#include <machine/pc/bios.h>
#include <machine/pcb.h>
#include <machine/pcb_ext.h>
#include <machine/proc.h>
#include <machine/reg.h>
#include <machine/sigframe.h>
#include <machine/specialreg.h>
#include <machine/sysarch.h>
#include <machine/trap.h>
#include <x86/ucode.h>
#include <machine/vm86.h>
#include <x86/init.h>
#ifdef PERFMON
#include <machine/perfmon.h>
#endif
#ifdef SMP
#include <machine/smp.h>
#endif
#ifdef FDT
#include <x86/fdt.h>
#endif

#ifdef DEV_APIC
#include <x86/apicvar.h>
#endif

#ifdef DEV_ISA
#include <x86/isa/icu.h>
#endif

/* Sanity check for __curthread() */
CTASSERT(offsetof(struct pcpu, pc_curthread) == 0);

register_t init386(int first);
void dblfault_handler(void);
void identify_cpu(void);

static void cpu_startup(void *);
static void fpstate_drop(struct thread *td);
static void get_fpcontext(struct thread *td, mcontext_t *mcp,
    char *xfpusave, size_t xfpusave_len);
static int  set_fpcontext(struct thread *td, mcontext_t *mcp,
    char *xfpustate, size_t xfpustate_len);
SYSINIT(cpu, SI_SUB_CPU, SI_ORDER_FIRST, cpu_startup, NULL);

/* Intel ICH registers */
#define ICH_PMBASE	0x400
#define ICH_SMI_EN	ICH_PMBASE + 0x30

int	_udatasel, _ucodesel;
u_int	basemem;

int cold = 1;

#ifdef COMPAT_43
static void osendsig(sig_t catcher, ksiginfo_t *, sigset_t *mask);
#endif
#ifdef COMPAT_FREEBSD4
static void freebsd4_sendsig(sig_t catcher, ksiginfo_t *, sigset_t *mask);
#endif

long Maxmem = 0;
long realmem = 0;

#ifdef PAE
FEATURE(pae, "Physical Address Extensions");
#endif

/*
 * The number of PHYSMAP entries must be one less than the number of
 * PHYSSEG entries because the PHYSMAP entry that spans the largest
 * physical address that is accessible by ISA DMA is split into two
 * PHYSSEG entries.
 */
#define	PHYSMAP_SIZE	(2 * (VM_PHYSSEG_MAX - 1))

vm_paddr_t phys_avail[PHYSMAP_SIZE + 2];
vm_paddr_t dump_avail[PHYSMAP_SIZE + 2];

/* must be 2 less so 0 0 can signal end of chunks */
#define	PHYS_AVAIL_ARRAY_END (nitems(phys_avail) - 2)
#define	DUMP_AVAIL_ARRAY_END (nitems(dump_avail) - 2)

struct kva_md_info kmi;

static struct trapframe proc0_tf;
struct pcpu __pcpu[MAXCPU];

struct mtx icu_lock;

struct mem_range_softc mem_range_softc;

extern char start_exceptions[], end_exceptions[];

extern struct sysentvec elf32_freebsd_sysvec;

/* Default init_ops implementation. */
struct init_ops init_ops = {
	.early_clock_source_init =	i8254_init,
	.early_delay =			i8254_delay,
#ifdef DEV_APIC
	.msi_init =			msi_init,
#endif
};

static void
cpu_startup(dummy)
	void *dummy;
{
	uintmax_t memsize;
	char *sysenv;

	/*
	 * On MacBooks, we need to disallow the legacy USB circuit to
	 * generate an SMI# because this can cause several problems,
	 * namely: incorrect CPU frequency detection and failure to
	 * start the APs.
	 * We do this by disabling a bit in the SMI_EN (SMI Control and
	 * Enable register) of the Intel ICH LPC Interface Bridge.
	 */
	sysenv = kern_getenv("smbios.system.product");
	if (sysenv != NULL) {
		if (strncmp(sysenv, "MacBook1,1", 10) == 0 ||
		    strncmp(sysenv, "MacBook3,1", 10) == 0 ||
		    strncmp(sysenv, "MacBook4,1", 10) == 0 ||
		    strncmp(sysenv, "MacBookPro1,1", 13) == 0 ||
		    strncmp(sysenv, "MacBookPro1,2", 13) == 0 ||
		    strncmp(sysenv, "MacBookPro3,1", 13) == 0 ||
		    strncmp(sysenv, "MacBookPro4,1", 13) == 0 ||
		    strncmp(sysenv, "Macmini1,1", 10) == 0) {
			if (bootverbose)
				printf("Disabling LEGACY_USB_EN bit on "
				    "Intel ICH.\n");
			outl(ICH_SMI_EN, inl(ICH_SMI_EN) & ~0x8);
		}
		freeenv(sysenv);
	}

	/*
	 * Good {morning,afternoon,evening,night}.
	 */
	startrtclock();
	printcpuinfo();
	panicifcpuunsupported();
#ifdef PERFMON
	perfmon_init();
#endif

	/*
	 * Display physical memory if SMBIOS reports reasonable amount.
	 */
	memsize = 0;
	sysenv = kern_getenv("smbios.memory.enabled");
	if (sysenv != NULL) {
		memsize = (uintmax_t)strtoul(sysenv, (char **)NULL, 10) << 10;
		freeenv(sysenv);
	}
	if (memsize < ptoa((uintmax_t)vm_free_count()))
		memsize = ptoa((uintmax_t)Maxmem);
	printf("real memory  = %ju (%ju MB)\n", memsize, memsize >> 20);
	realmem = atop(memsize);

	/*
	 * Display any holes after the first chunk of extended memory.
	 */
	if (bootverbose) {
		int indx;

		printf("Physical memory chunk(s):\n");
		for (indx = 0; phys_avail[indx + 1] != 0; indx += 2) {
			vm_paddr_t size;

			size = phys_avail[indx + 1] - phys_avail[indx];
			printf(
			    "0x%016jx - 0x%016jx, %ju bytes (%ju pages)\n",
			    (uintmax_t)phys_avail[indx],
			    (uintmax_t)phys_avail[indx + 1] - 1,
			    (uintmax_t)size, (uintmax_t)size / PAGE_SIZE);
		}
	}

	vm_ksubmap_init(&kmi);

	printf("avail memory = %ju (%ju MB)\n",
	    ptoa((uintmax_t)vm_free_count()),
	    ptoa((uintmax_t)vm_free_count()) / 1048576);

	/*
	 * Set up buffers, so they can be used to read disk labels.
	 */
	bufinit();
	vm_pager_bufferinit();
	cpu_setregs();
}

/*
 * Send an interrupt to process.
 *
 * Stack is set up to allow sigcode stored
 * at top to call routine, followed by call
 * to sigreturn routine below.  After sigreturn
 * resets the signal mask, the stack, and the
 * frame pointer, it returns to the user
 * specified pc, psl.
 */
#ifdef COMPAT_43
static void
osendsig(sig_t catcher, ksiginfo_t *ksi, sigset_t *mask)
{
	struct osigframe sf, *fp;
	struct proc *p;
	struct thread *td;
	struct sigacts *psp;
	struct trapframe *regs;
	int sig;
	int oonstack;

	td = curthread;
	p = td->td_proc;
	PROC_LOCK_ASSERT(p, MA_OWNED);
	sig = ksi->ksi_signo;
	psp = p->p_sigacts;
	mtx_assert(&psp->ps_mtx, MA_OWNED);
	regs = td->td_frame;
	oonstack = sigonstack(regs->tf_esp);

	/* Allocate space for the signal handler context. */
	if ((td->td_pflags & TDP_ALTSTACK) && !oonstack &&
	    SIGISMEMBER(psp->ps_sigonstack, sig)) {
		fp = (struct osigframe *)((uintptr_t)td->td_sigstk.ss_sp +
		    td->td_sigstk.ss_size - sizeof(struct osigframe));
#if defined(COMPAT_43)
		td->td_sigstk.ss_flags |= SS_ONSTACK;
#endif
	} else
		fp = (struct osigframe *)regs->tf_esp - 1;

	/* Build the argument list for the signal handler. */
	sf.sf_signum = sig;
	sf.sf_scp = (register_t)&fp->sf_siginfo.si_sc;
	bzero(&sf.sf_siginfo, sizeof(sf.sf_siginfo));
	if (SIGISMEMBER(psp->ps_siginfo, sig)) {
		/* Signal handler installed with SA_SIGINFO. */
		sf.sf_arg2 = (register_t)&fp->sf_siginfo;
		sf.sf_siginfo.si_signo = sig;
		sf.sf_siginfo.si_code = ksi->ksi_code;
		sf.sf_ahu.sf_action = (__osiginfohandler_t *)catcher;
		sf.sf_addr = 0;
	} else {
		/* Old FreeBSD-style arguments. */
		sf.sf_arg2 = ksi->ksi_code;
		sf.sf_addr = (register_t)ksi->ksi_addr;
		sf.sf_ahu.sf_handler = catcher;
	}
	mtx_unlock(&psp->ps_mtx);
	PROC_UNLOCK(p);

	/* Save most if not all of trap frame. */
	sf.sf_siginfo.si_sc.sc_eax = regs->tf_eax;
	sf.sf_siginfo.si_sc.sc_ebx = regs->tf_ebx;
	sf.sf_siginfo.si_sc.sc_ecx = regs->tf_ecx;
	sf.sf_siginfo.si_sc.sc_edx = regs->tf_edx;
	sf.sf_siginfo.si_sc.sc_esi = regs->tf_esi;
	sf.sf_siginfo.si_sc.sc_edi = regs->tf_edi;
	sf.sf_siginfo.si_sc.sc_cs = regs->tf_cs;
	sf.sf_siginfo.si_sc.sc_ds = regs->tf_ds;
	sf.sf_siginfo.si_sc.sc_ss = regs->tf_ss;
	sf.sf_siginfo.si_sc.sc_es = regs->tf_es;
	sf.sf_siginfo.si_sc.sc_fs = regs->tf_fs;
	sf.sf_siginfo.si_sc.sc_gs = rgs();
	sf.sf_siginfo.si_sc.sc_isp = regs->tf_isp;

	/* Build the signal context to be used by osigreturn(). */
	sf.sf_siginfo.si_sc.sc_onstack = (oonstack) ? 1 : 0;
	SIG2OSIG(*mask, sf.sf_siginfo.si_sc.sc_mask);
	sf.sf_siginfo.si_sc.sc_sp = regs->tf_esp;
	sf.sf_siginfo.si_sc.sc_fp = regs->tf_ebp;
	sf.sf_siginfo.si_sc.sc_pc = regs->tf_eip;
	sf.sf_siginfo.si_sc.sc_ps = regs->tf_eflags;
	sf.sf_siginfo.si_sc.sc_trapno = regs->tf_trapno;
	sf.sf_siginfo.si_sc.sc_err = regs->tf_err;

	/*
	 * If we're a vm86 process, we want to save the segment registers.
	 * We also change eflags to be our emulated eflags, not the actual
	 * eflags.
	 */
	if (regs->tf_eflags & PSL_VM) {
		/* XXX confusing names: `tf' isn't a trapframe; `regs' is. */
		struct trapframe_vm86 *tf = (struct trapframe_vm86 *)regs;
		struct vm86_kernel *vm86 = &td->td_pcb->pcb_ext->ext_vm86;

		sf.sf_siginfo.si_sc.sc_gs = tf->tf_vm86_gs;
		sf.sf_siginfo.si_sc.sc_fs = tf->tf_vm86_fs;
		sf.sf_siginfo.si_sc.sc_es = tf->tf_vm86_es;
		sf.sf_siginfo.si_sc.sc_ds = tf->tf_vm86_ds;

		if (vm86->vm86_has_vme == 0)
			sf.sf_siginfo.si_sc.sc_ps =
			    (tf->tf_eflags & ~(PSL_VIF | PSL_VIP)) |
			    (vm86->vm86_eflags & (PSL_VIF | PSL_VIP));

		/* See sendsig() for comments. */
		tf->tf_eflags &= ~(PSL_VM | PSL_NT | PSL_VIF | PSL_VIP);
	}

	/*
	 * Copy the sigframe out to the user's stack.
	 */
	if (copyout(&sf, fp, sizeof(*fp)) != 0) {
		PROC_LOCK(p);
		sigexit(td, SIGILL);
	}

	regs->tf_esp = (int)fp;
	if (p->p_sysent->sv_sigcode_base != 0) {
		regs->tf_eip = p->p_sysent->sv_sigcode_base + szsigcode -
		    szosigcode;
	} else {
		/* a.out sysentvec does not use shared page */
		regs->tf_eip = p->p_sysent->sv_psstrings - szosigcode;
	}
	regs->tf_eflags &= ~(PSL_T | PSL_D);
	regs->tf_cs = _ucodesel;
	regs->tf_ds = _udatasel;
	regs->tf_es = _udatasel;
	regs->tf_fs = _udatasel;
	load_gs(_udatasel);
	regs->tf_ss = _udatasel;
	PROC_LOCK(p);
	mtx_lock(&psp->ps_mtx);
}
#endif /* COMPAT_43 */

#ifdef COMPAT_FREEBSD4
static void
freebsd4_sendsig(sig_t catcher, ksiginfo_t *ksi, sigset_t *mask)
{
	struct sigframe4 sf, *sfp;
	struct proc *p;
	struct thread *td;
	struct sigacts *psp;
	struct trapframe *regs;
	int sig;
	int oonstack;

	td = curthread;
	p = td->td_proc;
	PROC_LOCK_ASSERT(p, MA_OWNED);
	sig = ksi->ksi_signo;
	psp = p->p_sigacts;
	mtx_assert(&psp->ps_mtx, MA_OWNED);
	regs = td->td_frame;
	oonstack = sigonstack(regs->tf_esp);

	/* Save user context. */
	bzero(&sf, sizeof(sf));
	sf.sf_uc.uc_sigmask = *mask;
	sf.sf_uc.uc_stack = td->td_sigstk;
	sf.sf_uc.uc_stack.ss_flags = (td->td_pflags & TDP_ALTSTACK)
	    ? ((oonstack) ? SS_ONSTACK : 0) : SS_DISABLE;
	sf.sf_uc.uc_mcontext.mc_onstack = (oonstack) ? 1 : 0;
	sf.sf_uc.uc_mcontext.mc_gs = rgs();
	bcopy(regs, &sf.sf_uc.uc_mcontext.mc_fs, sizeof(*regs));
	bzero(sf.sf_uc.uc_mcontext.mc_fpregs,
	    sizeof(sf.sf_uc.uc_mcontext.mc_fpregs));
	bzero(sf.sf_uc.uc_mcontext.__spare__,
	    sizeof(sf.sf_uc.uc_mcontext.__spare__));
	bzero(sf.sf_uc.__spare__, sizeof(sf.sf_uc.__spare__));

	/* Allocate space for the signal handler context. */
	if ((td->td_pflags & TDP_ALTSTACK) != 0 && !oonstack &&
	    SIGISMEMBER(psp->ps_sigonstack, sig)) {
		sfp = (struct sigframe4 *)((uintptr_t)td->td_sigstk.ss_sp +
		    td->td_sigstk.ss_size - sizeof(struct sigframe4));
#if defined(COMPAT_43)
		td->td_sigstk.ss_flags |= SS_ONSTACK;
#endif
	} else
		sfp = (struct sigframe4 *)regs->tf_esp - 1;

	/* Build the argument list for the signal handler. */
	sf.sf_signum = sig;
	sf.sf_ucontext = (register_t)&sfp->sf_uc;
	bzero(&sf.sf_si, sizeof(sf.sf_si));
	if (SIGISMEMBER(psp->ps_siginfo, sig)) {
		/* Signal handler installed with SA_SIGINFO. */
		sf.sf_siginfo = (register_t)&sfp->sf_si;
		sf.sf_ahu.sf_action = (__siginfohandler_t *)catcher;

		/* Fill in POSIX parts */
		sf.sf_si.si_signo = sig;
		sf.sf_si.si_code = ksi->ksi_code;
		sf.sf_si.si_addr = ksi->ksi_addr;
	} else {
		/* Old FreeBSD-style arguments. */
		sf.sf_siginfo = ksi->ksi_code;
		sf.sf_addr = (register_t)ksi->ksi_addr;
		sf.sf_ahu.sf_handler = catcher;
	}
	mtx_unlock(&psp->ps_mtx);
	PROC_UNLOCK(p);

	/*
	 * If we're a vm86 process, we want to save the segment registers.
	 * We also change eflags to be our emulated eflags, not the actual
	 * eflags.
	 */
	if (regs->tf_eflags & PSL_VM) {
		struct trapframe_vm86 *tf = (struct trapframe_vm86 *)regs;
		struct vm86_kernel *vm86 = &td->td_pcb->pcb_ext->ext_vm86;

		sf.sf_uc.uc_mcontext.mc_gs = tf->tf_vm86_gs;
		sf.sf_uc.uc_mcontext.mc_fs = tf->tf_vm86_fs;
		sf.sf_uc.uc_mcontext.mc_es = tf->tf_vm86_es;
		sf.sf_uc.uc_mcontext.mc_ds = tf->tf_vm86_ds;

		if (vm86->vm86_has_vme == 0)
			sf.sf_uc.uc_mcontext.mc_eflags =
			    (tf->tf_eflags & ~(PSL_VIF | PSL_VIP)) |
			    (vm86->vm86_eflags & (PSL_VIF | PSL_VIP));

		/*
		 * Clear PSL_NT to inhibit T_TSSFLT faults on return from
		 * syscalls made by the signal handler.  This just avoids
		 * wasting time for our lazy fixup of such faults.  PSL_NT
		 * does nothing in vm86 mode, but vm86 programs can set it
		 * almost legitimately in probes for old cpu types.
		 */
		tf->tf_eflags &= ~(PSL_VM | PSL_NT | PSL_VIF | PSL_VIP);
	}

	/*
	 * Copy the sigframe out to the user's stack.
	 */
	if (copyout(&sf, sfp, sizeof(*sfp)) != 0) {
		PROC_LOCK(p);
		sigexit(td, SIGILL);
	}

	regs->tf_esp = (int)sfp;
	regs->tf_eip = p->p_sysent->sv_sigcode_base + szsigcode -
	    szfreebsd4_sigcode;
	regs->tf_eflags &= ~(PSL_T | PSL_D);
	regs->tf_cs = _ucodesel;
	regs->tf_ds = _udatasel;
	regs->tf_es = _udatasel;
	regs->tf_fs = _udatasel;
	regs->tf_ss = _udatasel;
	PROC_LOCK(p);
	mtx_lock(&psp->ps_mtx);
}
#endif	/* COMPAT_FREEBSD4 */

void
sendsig(sig_t catcher, ksiginfo_t *ksi, sigset_t *mask)
{
	struct sigframe sf, *sfp;
	struct proc *p;
	struct thread *td;
	struct sigacts *psp;
	char *sp;
	struct trapframe *regs;
	struct segment_descriptor *sdp;
	char *xfpusave;
	size_t xfpusave_len;
	int sig;
	int oonstack;

	td = curthread;
	p = td->td_proc;
	PROC_LOCK_ASSERT(p, MA_OWNED);
	sig = ksi->ksi_signo;
	psp = p->p_sigacts;
	mtx_assert(&psp->ps_mtx, MA_OWNED);
#ifdef COMPAT_FREEBSD4
	if (SIGISMEMBER(psp->ps_freebsd4, sig)) {
		freebsd4_sendsig(catcher, ksi, mask);
		return;
	}
#endif
#ifdef COMPAT_43
	if (SIGISMEMBER(psp->ps_osigset, sig)) {
		osendsig(catcher, ksi, mask);
		return;
	}
#endif
	regs = td->td_frame;
	oonstack = sigonstack(regs->tf_esp);

	if (cpu_max_ext_state_size > sizeof(union savefpu) && use_xsave) {
		xfpusave_len = cpu_max_ext_state_size - sizeof(union savefpu);
		xfpusave = __builtin_alloca(xfpusave_len);
	} else {
		xfpusave_len = 0;
		xfpusave = NULL;
	}

	/* Save user context. */
	bzero(&sf, sizeof(sf));
	sf.sf_uc.uc_sigmask = *mask;
	sf.sf_uc.uc_stack = td->td_sigstk;
	sf.sf_uc.uc_stack.ss_flags = (td->td_pflags & TDP_ALTSTACK)
	    ? ((oonstack) ? SS_ONSTACK : 0) : SS_DISABLE;
	sf.sf_uc.uc_mcontext.mc_onstack = (oonstack) ? 1 : 0;
	sf.sf_uc.uc_mcontext.mc_gs = rgs();
	bcopy(regs, &sf.sf_uc.uc_mcontext.mc_fs, sizeof(*regs));
	sf.sf_uc.uc_mcontext.mc_len = sizeof(sf.sf_uc.uc_mcontext); /* magic */
	get_fpcontext(td, &sf.sf_uc.uc_mcontext, xfpusave, xfpusave_len);
	fpstate_drop(td);
	/*
	 * Unconditionally fill the fsbase and gsbase into the mcontext.
	 */
	sdp = &td->td_pcb->pcb_fsd;
	sf.sf_uc.uc_mcontext.mc_fsbase = sdp->sd_hibase << 24 |
	    sdp->sd_lobase;
	sdp = &td->td_pcb->pcb_gsd;
	sf.sf_uc.uc_mcontext.mc_gsbase = sdp->sd_hibase << 24 |
	    sdp->sd_lobase;
	bzero(sf.sf_uc.uc_mcontext.mc_spare2,
	    sizeof(sf.sf_uc.uc_mcontext.mc_spare2));
	bzero(sf.sf_uc.__spare__, sizeof(sf.sf_uc.__spare__));

	/* Allocate space for the signal handler context. */
	if ((td->td_pflags & TDP_ALTSTACK) != 0 && !oonstack &&
	    SIGISMEMBER(psp->ps_sigonstack, sig)) {
		sp = (char *)td->td_sigstk.ss_sp + td->td_sigstk.ss_size;
#if defined(COMPAT_43)
		td->td_sigstk.ss_flags |= SS_ONSTACK;
#endif
	} else
		sp = (char *)regs->tf_esp - 128;
	if (xfpusave != NULL) {
		sp -= xfpusave_len;
		sp = (char *)((unsigned int)sp & ~0x3F);
		sf.sf_uc.uc_mcontext.mc_xfpustate = (register_t)sp;
	}
	sp -= sizeof(struct sigframe);

	/* Align to 16 bytes. */
	sfp = (struct sigframe *)((unsigned int)sp & ~0xF);

	/* Build the argument list for the signal handler. */
	sf.sf_signum = sig;
	sf.sf_ucontext = (register_t)&sfp->sf_uc;
	bzero(&sf.sf_si, sizeof(sf.sf_si));
	if (SIGISMEMBER(psp->ps_siginfo, sig)) {
		/* Signal handler installed with SA_SIGINFO. */
		sf.sf_siginfo = (register_t)&sfp->sf_si;
		sf.sf_ahu.sf_action = (__siginfohandler_t *)catcher;

		/* Fill in POSIX parts */
		sf.sf_si = ksi->ksi_info;
		sf.sf_si.si_signo = sig; /* maybe a translated signal */
	} else {
		/* Old FreeBSD-style arguments. */
		sf.sf_siginfo = ksi->ksi_code;
		sf.sf_addr = (register_t)ksi->ksi_addr;
		sf.sf_ahu.sf_handler = catcher;
	}
	mtx_unlock(&psp->ps_mtx);
	PROC_UNLOCK(p);

	/*
	 * If we're a vm86 process, we want to save the segment registers.
	 * We also change eflags to be our emulated eflags, not the actual
	 * eflags.
	 */
	if (regs->tf_eflags & PSL_VM) {
		struct trapframe_vm86 *tf = (struct trapframe_vm86 *)regs;
		struct vm86_kernel *vm86 = &td->td_pcb->pcb_ext->ext_vm86;

		sf.sf_uc.uc_mcontext.mc_gs = tf->tf_vm86_gs;
		sf.sf_uc.uc_mcontext.mc_fs = tf->tf_vm86_fs;
		sf.sf_uc.uc_mcontext.mc_es = tf->tf_vm86_es;
		sf.sf_uc.uc_mcontext.mc_ds = tf->tf_vm86_ds;

		if (vm86->vm86_has_vme == 0)
			sf.sf_uc.uc_mcontext.mc_eflags =
			    (tf->tf_eflags & ~(PSL_VIF | PSL_VIP)) |
			    (vm86->vm86_eflags & (PSL_VIF | PSL_VIP));

		/*
		 * Clear PSL_NT to inhibit T_TSSFLT faults on return from
		 * syscalls made by the signal handler.  This just avoids
		 * wasting time for our lazy fixup of such faults.  PSL_NT
		 * does nothing in vm86 mode, but vm86 programs can set it
		 * almost legitimately in probes for old cpu types.
		 */
		tf->tf_eflags &= ~(PSL_VM | PSL_NT | PSL_VIF | PSL_VIP);
	}

	/*
	 * Copy the sigframe out to the user's stack.
	 */
	if (copyout(&sf, sfp, sizeof(*sfp)) != 0 ||
	    (xfpusave != NULL && copyout(xfpusave,
	    (void *)sf.sf_uc.uc_mcontext.mc_xfpustate, xfpusave_len)
	    != 0)) {
		PROC_LOCK(p);
		sigexit(td, SIGILL);
	}

	regs->tf_esp = (int)sfp;
	regs->tf_eip = p->p_sysent->sv_sigcode_base;
	if (regs->tf_eip == 0)
		regs->tf_eip = p->p_sysent->sv_psstrings - szsigcode;
	regs->tf_eflags &= ~(PSL_T | PSL_D);
	regs->tf_cs = _ucodesel;
	regs->tf_ds = _udatasel;
	regs->tf_es = _udatasel;
	regs->tf_fs = _udatasel;
	regs->tf_ss = _udatasel;
	PROC_LOCK(p);
	mtx_lock(&psp->ps_mtx);
}

/*
 * System call to cleanup state after a signal
 * has been taken.  Reset signal mask and
 * stack state from context left by sendsig (above).
 * Return to previous pc and psl as specified by
 * context left by sendsig. Check carefully to
 * make sure that the user has not modified the
 * state to gain improper privileges.
 *
 * MPSAFE
 */
#ifdef COMPAT_43
int
osigreturn(td, uap)
	struct thread *td;
	struct osigreturn_args /* {
		struct osigcontext *sigcntxp;
	} */ *uap;
{
	struct osigcontext sc;
	struct trapframe *regs;
	struct osigcontext *scp;
	int eflags, error;
	ksiginfo_t ksi;

	regs = td->td_frame;
	error = copyin(uap->sigcntxp, &sc, sizeof(sc));
	if (error != 0)
		return (error);
	scp = &sc;
	eflags = scp->sc_ps;
	if (eflags & PSL_VM) {
		struct trapframe_vm86 *tf = (struct trapframe_vm86 *)regs;
		struct vm86_kernel *vm86;

		/*
		 * if pcb_ext == 0 or vm86_inited == 0, the user hasn't
		 * set up the vm86 area, and we can't enter vm86 mode.
		 */
		if (td->td_pcb->pcb_ext == 0)
			return (EINVAL);
		vm86 = &td->td_pcb->pcb_ext->ext_vm86;
		if (vm86->vm86_inited == 0)
			return (EINVAL);

		/* Go back to user mode if both flags are set. */
		if ((eflags & PSL_VIP) && (eflags & PSL_VIF)) {
			ksiginfo_init_trap(&ksi);
			ksi.ksi_signo = SIGBUS;
			ksi.ksi_code = BUS_OBJERR;
			ksi.ksi_addr = (void *)regs->tf_eip;
			trapsignal(td, &ksi);
		}

		if (vm86->vm86_has_vme) {
			eflags = (tf->tf_eflags & ~VME_USERCHANGE) |
			    (eflags & VME_USERCHANGE) | PSL_VM;
		} else {
			vm86->vm86_eflags = eflags;	/* save VIF, VIP */
			eflags = (tf->tf_eflags & ~VM_USERCHANGE) |
			    (eflags & VM_USERCHANGE) | PSL_VM;
		}
		tf->tf_vm86_ds = scp->sc_ds;
		tf->tf_vm86_es = scp->sc_es;
		tf->tf_vm86_fs = scp->sc_fs;
		tf->tf_vm86_gs = scp->sc_gs;
		tf->tf_ds = _udatasel;
		tf->tf_es = _udatasel;
		tf->tf_fs = _udatasel;
	} else {
		/*
		 * Don't allow users to change privileged or reserved flags.
		 */
		if (!EFL_SECURE(eflags, regs->tf_eflags)) {
	    		return (EINVAL);
		}

		/*
		 * Don't allow users to load a valid privileged %cs.  Let the
		 * hardware check for invalid selectors, excess privilege in
		 * other selectors, invalid %eip's and invalid %esp's.
		 */
		if (!CS_SECURE(scp->sc_cs)) {
			ksiginfo_init_trap(&ksi);
			ksi.ksi_signo = SIGBUS;
			ksi.ksi_code = BUS_OBJERR;
			ksi.ksi_trapno = T_PROTFLT;
			ksi.ksi_addr = (void *)regs->tf_eip;
			trapsignal(td, &ksi);
			return (EINVAL);
		}
		regs->tf_ds = scp->sc_ds;
		regs->tf_es = scp->sc_es;
		regs->tf_fs = scp->sc_fs;
	}

	/* Restore remaining registers. */
	regs->tf_eax = scp->sc_eax;
	regs->tf_ebx = scp->sc_ebx;
	regs->tf_ecx = scp->sc_ecx;
	regs->tf_edx = scp->sc_edx;
	regs->tf_esi = scp->sc_esi;
	regs->tf_edi = scp->sc_edi;
	regs->tf_cs = scp->sc_cs;
	regs->tf_ss = scp->sc_ss;
	regs->tf_isp = scp->sc_isp;
	regs->tf_ebp = scp->sc_fp;
	regs->tf_esp = scp->sc_sp;
	regs->tf_eip = scp->sc_pc;
	regs->tf_eflags = eflags;

#if defined(COMPAT_43)
	if (scp->sc_onstack & 1)
		td->td_sigstk.ss_flags |= SS_ONSTACK;
	else
		td->td_sigstk.ss_flags &= ~SS_ONSTACK;
#endif
	kern_sigprocmask(td, SIG_SETMASK, (sigset_t *)&scp->sc_mask, NULL,
	    SIGPROCMASK_OLD);
	return (EJUSTRETURN);
}
#endif /* COMPAT_43 */

#ifdef COMPAT_FREEBSD4
/*
 * MPSAFE
 */
int
freebsd4_sigreturn(td, uap)
	struct thread *td;
	struct freebsd4_sigreturn_args /* {
		const ucontext4 *sigcntxp;
	} */ *uap;
{
	struct ucontext4 uc;
	struct trapframe *regs;
	struct ucontext4 *ucp;
	int cs, eflags, error;
	ksiginfo_t ksi;

	error = copyin(uap->sigcntxp, &uc, sizeof(uc));
	if (error != 0)
		return (error);
	ucp = &uc;
	regs = td->td_frame;
	eflags = ucp->uc_mcontext.mc_eflags;
	if (eflags & PSL_VM) {
		struct trapframe_vm86 *tf = (struct trapframe_vm86 *)regs;
		struct vm86_kernel *vm86;

		/*
		 * if pcb_ext == 0 or vm86_inited == 0, the user hasn't
		 * set up the vm86 area, and we can't enter vm86 mode.
		 */
		if (td->td_pcb->pcb_ext == 0)
			return (EINVAL);
		vm86 = &td->td_pcb->pcb_ext->ext_vm86;
		if (vm86->vm86_inited == 0)
			return (EINVAL);

		/* Go back to user mode if both flags are set. */
		if ((eflags & PSL_VIP) && (eflags & PSL_VIF)) {
			ksiginfo_init_trap(&ksi);
			ksi.ksi_signo = SIGBUS;
			ksi.ksi_code = BUS_OBJERR;
			ksi.ksi_addr = (void *)regs->tf_eip;
			trapsignal(td, &ksi);
		}
		if (vm86->vm86_has_vme) {
			eflags = (tf->tf_eflags & ~VME_USERCHANGE) |
			    (eflags & VME_USERCHANGE) | PSL_VM;
		} else {
			vm86->vm86_eflags = eflags;	/* save VIF, VIP */
			eflags = (tf->tf_eflags & ~VM_USERCHANGE) |
			    (eflags & VM_USERCHANGE) | PSL_VM;
		}
		bcopy(&ucp->uc_mcontext.mc_fs, tf, sizeof(struct trapframe));
		tf->tf_eflags = eflags;
		tf->tf_vm86_ds = tf->tf_ds;
		tf->tf_vm86_es = tf->tf_es;
		tf->tf_vm86_fs = tf->tf_fs;
		tf->tf_vm86_gs = ucp->uc_mcontext.mc_gs;
		tf->tf_ds = _udatasel;
		tf->tf_es = _udatasel;
		tf->tf_fs = _udatasel;
	} else {
		/*
		 * Don't allow users to change privileged or reserved flags.
		 */
		if (!EFL_SECURE(eflags, regs->tf_eflags)) {
			uprintf("pid %d (%s): freebsd4_sigreturn eflags = 0x%x\n",
			    td->td_proc->p_pid, td->td_name, eflags);
	    		return (EINVAL);
		}

		/*
		 * Don't allow users to load a valid privileged %cs.  Let the
		 * hardware check for invalid selectors, excess privilege in
		 * other selectors, invalid %eip's and invalid %esp's.
		 */
		cs = ucp->uc_mcontext.mc_cs;
		if (!CS_SECURE(cs)) {
			uprintf("pid %d (%s): freebsd4_sigreturn cs = 0x%x\n",
			    td->td_proc->p_pid, td->td_name, cs);
			ksiginfo_init_trap(&ksi);
			ksi.ksi_signo = SIGBUS;
			ksi.ksi_code = BUS_OBJERR;
			ksi.ksi_trapno = T_PROTFLT;
			ksi.ksi_addr = (void *)regs->tf_eip;
			trapsignal(td, &ksi);
			return (EINVAL);
		}

		bcopy(&ucp->uc_mcontext.mc_fs, regs, sizeof(*regs));
	}

#if defined(COMPAT_43)
	if (ucp->uc_mcontext.mc_onstack & 1)
		td->td_sigstk.ss_flags |= SS_ONSTACK;
	else
		td->td_sigstk.ss_flags &= ~SS_ONSTACK;
#endif
	kern_sigprocmask(td, SIG_SETMASK, &ucp->uc_sigmask, NULL, 0);
	return (EJUSTRETURN);
}
#endif	/* COMPAT_FREEBSD4 */

/*
 * MPSAFE
 */
int
sys_sigreturn(td, uap)
	struct thread *td;
	struct sigreturn_args /* {
		const struct __ucontext *sigcntxp;
	} */ *uap;
{
	ucontext_t uc;
	struct proc *p;
	struct trapframe *regs;
	ucontext_t *ucp;
	char *xfpustate;
	size_t xfpustate_len;
	int cs, eflags, error, ret;
	ksiginfo_t ksi;

	p = td->td_proc;

	error = copyin(uap->sigcntxp, &uc, sizeof(uc));
	if (error != 0)
		return (error);
	ucp = &uc;
	if ((ucp->uc_mcontext.mc_flags & ~_MC_FLAG_MASK) != 0) {
		uprintf("pid %d (%s): sigreturn mc_flags %x\n", p->p_pid,
		    td->td_name, ucp->uc_mcontext.mc_flags);
		return (EINVAL);
	}
	regs = td->td_frame;
	eflags = ucp->uc_mcontext.mc_eflags;
	if (eflags & PSL_VM) {
		struct trapframe_vm86 *tf = (struct trapframe_vm86 *)regs;
		struct vm86_kernel *vm86;

		/*
		 * if pcb_ext == 0 or vm86_inited == 0, the user hasn't
		 * set up the vm86 area, and we can't enter vm86 mode.
		 */
		if (td->td_pcb->pcb_ext == 0)
			return (EINVAL);
		vm86 = &td->td_pcb->pcb_ext->ext_vm86;
		if (vm86->vm86_inited == 0)
			return (EINVAL);

		/* Go back to user mode if both flags are set. */
		if ((eflags & PSL_VIP) && (eflags & PSL_VIF)) {
			ksiginfo_init_trap(&ksi);
			ksi.ksi_signo = SIGBUS;
			ksi.ksi_code = BUS_OBJERR;
			ksi.ksi_addr = (void *)regs->tf_eip;
			trapsignal(td, &ksi);
		}

		if (vm86->vm86_has_vme) {
			eflags = (tf->tf_eflags & ~VME_USERCHANGE) |
			    (eflags & VME_USERCHANGE) | PSL_VM;
		} else {
			vm86->vm86_eflags = eflags;	/* save VIF, VIP */
			eflags = (tf->tf_eflags & ~VM_USERCHANGE) |
			    (eflags & VM_USERCHANGE) | PSL_VM;
		}
		bcopy(&ucp->uc_mcontext.mc_fs, tf, sizeof(struct trapframe));
		tf->tf_eflags = eflags;
		tf->tf_vm86_ds = tf->tf_ds;
		tf->tf_vm86_es = tf->tf_es;
		tf->tf_vm86_fs = tf->tf_fs;
		tf->tf_vm86_gs = ucp->uc_mcontext.mc_gs;
		tf->tf_ds = _udatasel;
		tf->tf_es = _udatasel;
		tf->tf_fs = _udatasel;
	} else {
		/*
		 * Don't allow users to change privileged or reserved flags.
		 */
		if (!EFL_SECURE(eflags, regs->tf_eflags)) {
			uprintf("pid %d (%s): sigreturn eflags = 0x%x\n",
			    td->td_proc->p_pid, td->td_name, eflags);
	    		return (EINVAL);
		}

		/*
		 * Don't allow users to load a valid privileged %cs.  Let the
		 * hardware check for invalid selectors, excess privilege in
		 * other selectors, invalid %eip's and invalid %esp's.
		 */
		cs = ucp->uc_mcontext.mc_cs;
		if (!CS_SECURE(cs)) {
			uprintf("pid %d (%s): sigreturn cs = 0x%x\n",
			    td->td_proc->p_pid, td->td_name, cs);
			ksiginfo_init_trap(&ksi);
			ksi.ksi_signo = SIGBUS;
			ksi.ksi_code = BUS_OBJERR;
			ksi.ksi_trapno = T_PROTFLT;
			ksi.ksi_addr = (void *)regs->tf_eip;
			trapsignal(td, &ksi);
			return (EINVAL);
		}

		if ((uc.uc_mcontext.mc_flags & _MC_HASFPXSTATE) != 0) {
			xfpustate_len = uc.uc_mcontext.mc_xfpustate_len;
			if (xfpustate_len > cpu_max_ext_state_size -
			    sizeof(union savefpu)) {
				uprintf(
			    "pid %d (%s): sigreturn xfpusave_len = 0x%zx\n",
				    p->p_pid, td->td_name, xfpustate_len);
				return (EINVAL);
			}
			xfpustate = __builtin_alloca(xfpustate_len);
			error = copyin((const void *)uc.uc_mcontext.mc_xfpustate,
			    xfpustate, xfpustate_len);
			if (error != 0) {
				uprintf(
	"pid %d (%s): sigreturn copying xfpustate failed\n",
				    p->p_pid, td->td_name);
				return (error);
			}
		} else {
			xfpustate = NULL;
			xfpustate_len = 0;
		}
		ret = set_fpcontext(td, &ucp->uc_mcontext, xfpustate,
		    xfpustate_len);
		if (ret != 0)
			return (ret);
		bcopy(&ucp->uc_mcontext.mc_fs, regs, sizeof(*regs));
	}

#if defined(COMPAT_43)
	if (ucp->uc_mcontext.mc_onstack & 1)
		td->td_sigstk.ss_flags |= SS_ONSTACK;
	else
		td->td_sigstk.ss_flags &= ~SS_ONSTACK;
#endif

	kern_sigprocmask(td, SIG_SETMASK, &ucp->uc_sigmask, NULL, 0);
	return (EJUSTRETURN);
}

#ifdef COMPAT_43
static void
setup_priv_lcall_gate(struct proc *p)
{
	struct i386_ldt_args uap;
	union descriptor desc;
	u_int lcall_addr;

	bzero(&uap, sizeof(uap));
	uap.start = 0;
	uap.num = 1;
	lcall_addr = p->p_sysent->sv_psstrings - sz_lcall_tramp;
	bzero(&desc, sizeof(desc));
	desc.sd.sd_type = SDT_MEMERA;
	desc.sd.sd_dpl = SEL_UPL;
	desc.sd.sd_p = 1;
	desc.sd.sd_def32 = 1;
	desc.sd.sd_gran = 1;
	desc.sd.sd_lolimit = 0xffff;
	desc.sd.sd_hilimit = 0xf;
	desc.sd.sd_lobase = lcall_addr;
	desc.sd.sd_hibase = lcall_addr >> 24;
	i386_set_ldt(curthread, &uap, &desc);
}
#endif

/*
 * Reset registers to default values on exec.
 */
void
exec_setregs(struct thread *td, struct image_params *imgp, u_long stack)
{
	struct trapframe *regs;
	struct pcb *pcb;
	register_t saved_eflags;

	regs = td->td_frame;
	pcb = td->td_pcb;

	/* Reset pc->pcb_gs and %gs before possibly invalidating it. */
	pcb->pcb_gs = _udatasel;
	load_gs(_udatasel);

	mtx_lock_spin(&dt_lock);
	if (td->td_proc->p_md.md_ldt != NULL)
		user_ldt_free(td);
	else
		mtx_unlock_spin(&dt_lock);

#ifdef COMPAT_43
	if (td->td_proc->p_sysent->sv_psstrings !=
	    elf32_freebsd_sysvec.sv_psstrings)
		setup_priv_lcall_gate(td->td_proc);
#endif

	/*
	 * Reset the fs and gs bases.  The values from the old address
	 * space do not make sense for the new program.  In particular,
	 * gsbase might be the TLS base for the old program but the new
	 * program has no TLS now.
	 */
	set_fsbase(td, 0);
	set_gsbase(td, 0);

	/* Make sure edx is 0x0 on entry. Linux binaries depend on it. */
	saved_eflags = regs->tf_eflags & PSL_T;
	bzero((char *)regs, sizeof(struct trapframe));
	regs->tf_eip = imgp->entry_addr;
	regs->tf_esp = stack;
	regs->tf_eflags = PSL_USER | saved_eflags;
	regs->tf_ss = _udatasel;
	regs->tf_ds = _udatasel;
	regs->tf_es = _udatasel;
	regs->tf_fs = _udatasel;
	regs->tf_cs = _ucodesel;

	/* PS_STRINGS value for BSD/OS binaries.  It is 0 for non-BSD/OS. */
	regs->tf_ebx = imgp->ps_strings;

        /*
         * Reset the hardware debug registers if they were in use.
         * They won't have any meaning for the newly exec'd process.
         */
        if (pcb->pcb_flags & PCB_DBREGS) {
                pcb->pcb_dr0 = 0;
                pcb->pcb_dr1 = 0;
                pcb->pcb_dr2 = 0;
                pcb->pcb_dr3 = 0;
                pcb->pcb_dr6 = 0;
                pcb->pcb_dr7 = 0;
                if (pcb == curpcb) {
		        /*
			 * Clear the debug registers on the running
			 * CPU, otherwise they will end up affecting
			 * the next process we switch to.
			 */
		        reset_dbregs();
                }
		pcb->pcb_flags &= ~PCB_DBREGS;
        }

	pcb->pcb_initial_npxcw = __INITIAL_NPXCW__;

	/*
	 * Drop the FP state if we hold it, so that the process gets a
	 * clean FP state if it uses the FPU again.
	 */
	fpstate_drop(td);
}

void
cpu_setregs(void)
{
	unsigned int cr0;

	cr0 = rcr0();

	/*
	 * CR0_MP, CR0_NE and CR0_TS are set for NPX (FPU) support:
	 *
	 * Prepare to trap all ESC (i.e., NPX) instructions and all WAIT
	 * instructions.  We must set the CR0_MP bit and use the CR0_TS
	 * bit to control the trap, because setting the CR0_EM bit does
	 * not cause WAIT instructions to trap.  It's important to trap
	 * WAIT instructions - otherwise the "wait" variants of no-wait
	 * control instructions would degenerate to the "no-wait" variants
	 * after FP context switches but work correctly otherwise.  It's
	 * particularly important to trap WAITs when there is no NPX -
	 * otherwise the "wait" variants would always degenerate.
	 *
	 * Try setting CR0_NE to get correct error reporting on 486DX's.
	 * Setting it should fail or do nothing on lesser processors.
	 */
	cr0 |= CR0_MP | CR0_NE | CR0_TS | CR0_WP | CR0_AM;
	load_cr0(cr0);
	load_gs(_udatasel);
}

u_long bootdev;		/* not a struct cdev *- encoding is different */
SYSCTL_ULONG(_machdep, OID_AUTO, guessed_bootdev,
	CTLFLAG_RD, &bootdev, 0, "Maybe the Boot device (not in struct cdev *format)");

static char bootmethod[16] = "BIOS";
SYSCTL_STRING(_machdep, OID_AUTO, bootmethod, CTLFLAG_RD, bootmethod, 0,
    "System firmware boot method");

/*
 * Initialize 386 and configure to run kernel
 */

/*
 * Initialize segments & interrupt table
 */

int _default_ldt;

struct mtx dt_lock;			/* lock for GDT and LDT */

union descriptor gdt0[NGDT];	/* initial global descriptor table */
union descriptor *gdt = gdt0;	/* global descriptor table */

union descriptor *ldt;		/* local descriptor table */

static struct gate_descriptor idt0[NIDT];
struct gate_descriptor *idt = &idt0[0];	/* interrupt descriptor table */

static struct i386tss *dblfault_tss;
static char *dblfault_stack;

static struct i386tss common_tss0;

vm_offset_t proc0kstack;

/*
 * software prototypes -- in more palatable form.
 *
 * GCODE_SEL through GUDATA_SEL must be in this order for syscall/sysret
 * GUFS_SEL and GUGS_SEL must be in this order (swtch.s knows it)
 */
struct soft_segment_descriptor gdt_segs[] = {
/* GNULL_SEL	0 Null Descriptor */
{	.ssd_base = 0x0,
	.ssd_limit = 0x0,
	.ssd_type = 0,
	.ssd_dpl = SEL_KPL,
	.ssd_p = 0,
	.ssd_xx = 0, .ssd_xx1 = 0,
	.ssd_def32 = 0,
	.ssd_gran = 0		},
/* GPRIV_SEL	1 SMP Per-Processor Private Data Descriptor */
{	.ssd_base = 0x0,
	.ssd_limit = 0xfffff,
	.ssd_type = SDT_MEMRWA,
	.ssd_dpl = SEL_KPL,
	.ssd_p = 1,
	.ssd_xx = 0, .ssd_xx1 = 0,
	.ssd_def32 = 1,
	.ssd_gran = 1		},
/* GUFS_SEL	2 %fs Descriptor for user */
{	.ssd_base = 0x0,
	.ssd_limit = 0xfffff,
	.ssd_type = SDT_MEMRWA,
	.ssd_dpl = SEL_UPL,
	.ssd_p = 1,
	.ssd_xx = 0, .ssd_xx1 = 0,
	.ssd_def32 = 1,
	.ssd_gran = 1		},
/* GUGS_SEL	3 %gs Descriptor for user */
{	.ssd_base = 0x0,
	.ssd_limit = 0xfffff,
	.ssd_type = SDT_MEMRWA,
	.ssd_dpl = SEL_UPL,
	.ssd_p = 1,
	.ssd_xx = 0, .ssd_xx1 = 0,
	.ssd_def32 = 1,
	.ssd_gran = 1		},
/* GCODE_SEL	4 Code Descriptor for kernel */
{	.ssd_base = 0x0,
	.ssd_limit = 0xfffff,
	.ssd_type = SDT_MEMERA,
	.ssd_dpl = SEL_KPL,
	.ssd_p = 1,
	.ssd_xx = 0, .ssd_xx1 = 0,
	.ssd_def32 = 1,
	.ssd_gran = 1		},
/* GDATA_SEL	5 Data Descriptor for kernel */
{	.ssd_base = 0x0,
	.ssd_limit = 0xfffff,
	.ssd_type = SDT_MEMRWA,
	.ssd_dpl = SEL_KPL,
	.ssd_p = 1,
	.ssd_xx = 0, .ssd_xx1 = 0,
	.ssd_def32 = 1,
	.ssd_gran = 1		},
/* GUCODE_SEL	6 Code Descriptor for user */
{	.ssd_base = 0x0,
	.ssd_limit = 0xfffff,
	.ssd_type = SDT_MEMERA,
	.ssd_dpl = SEL_UPL,
	.ssd_p = 1,
	.ssd_xx = 0, .ssd_xx1 = 0,
	.ssd_def32 = 1,
	.ssd_gran = 1		},
/* GUDATA_SEL	7 Data Descriptor for user */
{	.ssd_base = 0x0,
	.ssd_limit = 0xfffff,
	.ssd_type = SDT_MEMRWA,
	.ssd_dpl = SEL_UPL,
	.ssd_p = 1,
	.ssd_xx = 0, .ssd_xx1 = 0,
	.ssd_def32 = 1,
	.ssd_gran = 1		},
/* GBIOSLOWMEM_SEL 8 BIOS access to realmode segment 0x40, must be #8 in GDT */
{	.ssd_base = 0x400,
	.ssd_limit = 0xfffff,
	.ssd_type = SDT_MEMRWA,
	.ssd_dpl = SEL_KPL,
	.ssd_p = 1,
	.ssd_xx = 0, .ssd_xx1 = 0,
	.ssd_def32 = 1,
	.ssd_gran = 1		},
/* GPROC0_SEL	9 Proc 0 Tss Descriptor */
{
	.ssd_base = 0x0,
	.ssd_limit = sizeof(struct i386tss)-1,
	.ssd_type = SDT_SYS386TSS,
	.ssd_dpl = 0,
	.ssd_p = 1,
	.ssd_xx = 0, .ssd_xx1 = 0,
	.ssd_def32 = 0,
	.ssd_gran = 0		},
/* GLDT_SEL	10 LDT Descriptor */
{	.ssd_base = 0,
	.ssd_limit = sizeof(union descriptor) * NLDT - 1,
	.ssd_type = SDT_SYSLDT,
	.ssd_dpl = SEL_UPL,
	.ssd_p = 1,
	.ssd_xx = 0, .ssd_xx1 = 0,
	.ssd_def32 = 0,
	.ssd_gran = 0		},
/* GUSERLDT_SEL	11 User LDT Descriptor per process */
{	.ssd_base = 0,
	.ssd_limit = (512 * sizeof(union descriptor)-1),
	.ssd_type = SDT_SYSLDT,
	.ssd_dpl = 0,
	.ssd_p = 1,
	.ssd_xx = 0, .ssd_xx1 = 0,
	.ssd_def32 = 0,
	.ssd_gran = 0		},
/* GPANIC_SEL	12 Panic Tss Descriptor */
{	.ssd_base = 0,
	.ssd_limit = sizeof(struct i386tss)-1,
	.ssd_type = SDT_SYS386TSS,
	.ssd_dpl = 0,
	.ssd_p = 1,
	.ssd_xx = 0, .ssd_xx1 = 0,
	.ssd_def32 = 0,
	.ssd_gran = 0		},
/* GBIOSCODE32_SEL 13 BIOS 32-bit interface (32bit Code) */
{	.ssd_base = 0,
	.ssd_limit = 0xfffff,
	.ssd_type = SDT_MEMERA,
	.ssd_dpl = 0,
	.ssd_p = 1,
	.ssd_xx = 0, .ssd_xx1 = 0,
	.ssd_def32 = 0,
	.ssd_gran = 1		},
/* GBIOSCODE16_SEL 14 BIOS 32-bit interface (16bit Code) */
{	.ssd_base = 0,
	.ssd_limit = 0xfffff,
	.ssd_type = SDT_MEMERA,
	.ssd_dpl = 0,
	.ssd_p = 1,
	.ssd_xx = 0, .ssd_xx1 = 0,
	.ssd_def32 = 0,
	.ssd_gran = 1		},
/* GBIOSDATA_SEL 15 BIOS 32-bit interface (Data) */
{	.ssd_base = 0,
	.ssd_limit = 0xfffff,
	.ssd_type = SDT_MEMRWA,
	.ssd_dpl = 0,
	.ssd_p = 1,
	.ssd_xx = 0, .ssd_xx1 = 0,
	.ssd_def32 = 1,
	.ssd_gran = 1		},
/* GBIOSUTIL_SEL 16 BIOS 16-bit interface (Utility) */
{	.ssd_base = 0,
	.ssd_limit = 0xfffff,
	.ssd_type = SDT_MEMRWA,
	.ssd_dpl = 0,
	.ssd_p = 1,
	.ssd_xx = 0, .ssd_xx1 = 0,
	.ssd_def32 = 0,
	.ssd_gran = 1		},
/* GBIOSARGS_SEL 17 BIOS 16-bit interface (Arguments) */
{	.ssd_base = 0,
	.ssd_limit = 0xfffff,
	.ssd_type = SDT_MEMRWA,
	.ssd_dpl = 0,
	.ssd_p = 1,
	.ssd_xx = 0, .ssd_xx1 = 0,
	.ssd_def32 = 0,
	.ssd_gran = 1		},
/* GNDIS_SEL	18 NDIS Descriptor */
{	.ssd_base = 0x0,
	.ssd_limit = 0x0,
	.ssd_type = 0,
	.ssd_dpl = 0,
	.ssd_p = 0,
	.ssd_xx = 0, .ssd_xx1 = 0,
	.ssd_def32 = 0,
	.ssd_gran = 0		},
};

static struct soft_segment_descriptor ldt_segs[] = {
	/* Null Descriptor - overwritten by call gate */
{	.ssd_base = 0x0,
	.ssd_limit = 0x0,
	.ssd_type = 0,
	.ssd_dpl = 0,
	.ssd_p = 0,
	.ssd_xx = 0, .ssd_xx1 = 0,
	.ssd_def32 = 0,
	.ssd_gran = 0		},
	/* Null Descriptor - overwritten by call gate */
{	.ssd_base = 0x0,
	.ssd_limit = 0x0,
	.ssd_type = 0,
	.ssd_dpl = 0,
	.ssd_p = 0,
	.ssd_xx = 0, .ssd_xx1 = 0,
	.ssd_def32 = 0,
	.ssd_gran = 0		},
	/* Null Descriptor - overwritten by call gate */
{	.ssd_base = 0x0,
	.ssd_limit = 0x0,
	.ssd_type = 0,
	.ssd_dpl = 0,
	.ssd_p = 0,
	.ssd_xx = 0, .ssd_xx1 = 0,
	.ssd_def32 = 0,
	.ssd_gran = 0		},
	/* Code Descriptor for user */
{	.ssd_base = 0x0,
	.ssd_limit = 0xfffff,
	.ssd_type = SDT_MEMERA,
	.ssd_dpl = SEL_UPL,
	.ssd_p = 1,
	.ssd_xx = 0, .ssd_xx1 = 0,
	.ssd_def32 = 1,
	.ssd_gran = 1		},
	/* Null Descriptor - overwritten by call gate */
{	.ssd_base = 0x0,
	.ssd_limit = 0x0,
	.ssd_type = 0,
	.ssd_dpl = 0,
	.ssd_p = 0,
	.ssd_xx = 0, .ssd_xx1 = 0,
	.ssd_def32 = 0,
	.ssd_gran = 0		},
	/* Data Descriptor for user */
{	.ssd_base = 0x0,
	.ssd_limit = 0xfffff,
	.ssd_type = SDT_MEMRWA,
	.ssd_dpl = SEL_UPL,
	.ssd_p = 1,
	.ssd_xx = 0, .ssd_xx1 = 0,
	.ssd_def32 = 1,
	.ssd_gran = 1		},
};

uintptr_t setidt_disp;

void
setidt(int idx, inthand_t *func, int typ, int dpl, int selec)
{
	uintptr_t off;

	off = func != NULL ? (uintptr_t)func + setidt_disp : 0;
	setidt_nodisp(idx, off, typ, dpl, selec);
}

void
setidt_nodisp(int idx, uintptr_t off, int typ, int dpl, int selec)
{
	struct gate_descriptor *ip;

	ip = idt + idx;
	ip->gd_looffset = off;
	ip->gd_selector = selec;
	ip->gd_stkcpy = 0;
	ip->gd_xx = 0;
	ip->gd_type = typ;
	ip->gd_dpl = dpl;
	ip->gd_p = 1;
	ip->gd_hioffset = ((u_int)off) >> 16 ;
}

extern inthand_t
	IDTVEC(div), IDTVEC(dbg), IDTVEC(nmi), IDTVEC(bpt), IDTVEC(ofl),
	IDTVEC(bnd), IDTVEC(ill), IDTVEC(dna), IDTVEC(fpusegm),
	IDTVEC(tss), IDTVEC(missing), IDTVEC(stk), IDTVEC(prot),
	IDTVEC(page), IDTVEC(mchk), IDTVEC(rsvd), IDTVEC(fpu), IDTVEC(align),
	IDTVEC(xmm),
#ifdef KDTRACE_HOOKS
	IDTVEC(dtrace_ret),
#endif
#ifdef XENHVM
	IDTVEC(xen_intr_upcall),
#endif
	IDTVEC(int0x80_syscall);

#ifdef DDB
/*
 * Display the index and function name of any IDT entries that don't use
 * the default 'rsvd' entry point.
 */
DB_SHOW_COMMAND(idt, db_show_idt)
{
	struct gate_descriptor *ip;
	int idx;
	uintptr_t func, func_trm;
	bool trm;

	ip = idt;
	for (idx = 0; idx < NIDT && !db_pager_quit; idx++) {
		if (ip->gd_type == SDT_SYSTASKGT) {
			db_printf("%3d\t<TASK>\n", idx);
		} else {
			func = (ip->gd_hioffset << 16 | ip->gd_looffset);
			if (func >= PMAP_TRM_MIN_ADDRESS) {
				func_trm = func;
				func -= setidt_disp;
				trm = true;
			} else
				trm = false;
			if (func != (uintptr_t)&IDTVEC(rsvd)) {
				db_printf("%3d\t", idx);
				db_printsym(func, DB_STGY_PROC);
				if (trm)
					db_printf(" (trampoline %#x)",
					    func_trm);
				db_printf("\n");
			}
		}
		ip++;
	}
}

/* Show privileged registers. */
DB_SHOW_COMMAND(sysregs, db_show_sysregs)
{
	uint64_t idtr, gdtr;

	idtr = ridt();
	db_printf("idtr\t0x%08x/%04x\n",
	    (u_int)(idtr >> 16), (u_int)idtr & 0xffff);
	gdtr = rgdt();
	db_printf("gdtr\t0x%08x/%04x\n",
	    (u_int)(gdtr >> 16), (u_int)gdtr & 0xffff);
	db_printf("ldtr\t0x%04x\n", rldt());
	db_printf("tr\t0x%04x\n", rtr());
	db_printf("cr0\t0x%08x\n", rcr0());
	db_printf("cr2\t0x%08x\n", rcr2());
	db_printf("cr3\t0x%08x\n", rcr3());
	db_printf("cr4\t0x%08x\n", rcr4());
	if (rcr4() & CR4_XSAVE)
		db_printf("xcr0\t0x%016llx\n", rxcr(0));
	if (amd_feature & (AMDID_NX | AMDID_LM))
		db_printf("EFER\t0x%016llx\n", rdmsr(MSR_EFER));
	if (cpu_feature2 & (CPUID2_VMX | CPUID2_SMX))
		db_printf("FEATURES_CTL\t0x%016llx\n",
		    rdmsr(MSR_IA32_FEATURE_CONTROL));
	if ((cpu_vendor_id == CPU_VENDOR_INTEL ||
	    cpu_vendor_id == CPU_VENDOR_AMD) && CPUID_TO_FAMILY(cpu_id) >= 6)
		db_printf("DEBUG_CTL\t0x%016llx\n", rdmsr(MSR_DEBUGCTLMSR));
	if (cpu_feature & CPUID_PAT)
		db_printf("PAT\t0x%016llx\n", rdmsr(MSR_PAT));
}

DB_SHOW_COMMAND(dbregs, db_show_dbregs)
{

	db_printf("dr0\t0x%08x\n", rdr0());
	db_printf("dr1\t0x%08x\n", rdr1());
	db_printf("dr2\t0x%08x\n", rdr2());
	db_printf("dr3\t0x%08x\n", rdr3());
	db_printf("dr6\t0x%08x\n", rdr6());
	db_printf("dr7\t0x%08x\n", rdr7());
}

DB_SHOW_COMMAND(frame, db_show_frame)
{
	struct trapframe *frame;

	frame = have_addr ? (struct trapframe *)addr : curthread->td_frame;
	printf("ss %#x esp %#x efl %#x cs %#x eip %#x\n",
	    frame->tf_ss, frame->tf_esp, frame->tf_eflags, frame->tf_cs,
	    frame->tf_eip);
	printf("err %#x trapno %d\n", frame->tf_err, frame->tf_trapno);
	printf("ds %#x es %#x fs %#x\n",
	    frame->tf_ds, frame->tf_es, frame->tf_fs);
	printf("eax %#x ecx %#x edx %#x ebx %#x\n",
	    frame->tf_eax, frame->tf_ecx, frame->tf_edx, frame->tf_ebx);
	printf("ebp %#x esi %#x edi %#x\n",
	    frame->tf_ebp, frame->tf_esi, frame->tf_edi);

}
#endif

void
sdtossd(sd, ssd)
	struct segment_descriptor *sd;
	struct soft_segment_descriptor *ssd;
{
	ssd->ssd_base  = (sd->sd_hibase << 24) | sd->sd_lobase;
	ssd->ssd_limit = (sd->sd_hilimit << 16) | sd->sd_lolimit;
	ssd->ssd_type  = sd->sd_type;
	ssd->ssd_dpl   = sd->sd_dpl;
	ssd->ssd_p     = sd->sd_p;
	ssd->ssd_def32 = sd->sd_def32;
	ssd->ssd_gran  = sd->sd_gran;
}

static int
add_physmap_entry(uint64_t base, uint64_t length, vm_paddr_t *physmap,
    int *physmap_idxp)
{
	int i, insert_idx, physmap_idx;

	physmap_idx = *physmap_idxp;

	if (length == 0)
		return (1);

#ifndef PAE
	if (base > 0xffffffff) {
		printf("%uK of memory above 4GB ignored\n",
		    (u_int)(length / 1024));
		return (1);
	}
#endif

	/*
	 * Find insertion point while checking for overlap.  Start off by
	 * assuming the new entry will be added to the end.
	 */
	insert_idx = physmap_idx + 2;
	for (i = 0; i <= physmap_idx; i += 2) {
		if (base < physmap[i + 1]) {
			if (base + length <= physmap[i]) {
				insert_idx = i;
				break;
			}
			if (boothowto & RB_VERBOSE)
				printf(
		    "Overlapping memory regions, ignoring second region\n");
			return (1);
		}
	}

	/* See if we can prepend to the next entry. */
	if (insert_idx <= physmap_idx && base + length == physmap[insert_idx]) {
		physmap[insert_idx] = base;
		return (1);
	}

	/* See if we can append to the previous entry. */
	if (insert_idx > 0 && base == physmap[insert_idx - 1]) {
		physmap[insert_idx - 1] += length;
		return (1);
	}

	physmap_idx += 2;
	*physmap_idxp = physmap_idx;
	if (physmap_idx == PHYSMAP_SIZE) {
		printf(
		"Too many segments in the physical address map, giving up\n");
		return (0);
	}

	/*
	 * Move the last 'N' entries down to make room for the new
	 * entry if needed.
	 */
	for (i = physmap_idx; i > insert_idx; i -= 2) {
		physmap[i] = physmap[i - 2];
		physmap[i + 1] = physmap[i - 1];
	}

	/* Insert the new entry. */
	physmap[insert_idx] = base;
	physmap[insert_idx + 1] = base + length;
	return (1);
}

static int
add_smap_entry(struct bios_smap *smap, vm_paddr_t *physmap, int *physmap_idxp)
{
	if (boothowto & RB_VERBOSE)
		printf("SMAP type=%02x base=%016llx len=%016llx\n",
		    smap->type, smap->base, smap->length);

	if (smap->type != SMAP_TYPE_MEMORY)
		return (1);

	return (add_physmap_entry(smap->base, smap->length, physmap,
	    physmap_idxp));
}

static void
add_smap_entries(struct bios_smap *smapbase, vm_paddr_t *physmap,
    int *physmap_idxp)
{
	struct bios_smap *smap, *smapend;
	u_int32_t smapsize;
	/*
	 * Memory map from INT 15:E820.
	 *
	 * subr_module.c says:
	 * "Consumer may safely assume that size value precedes data."
	 * ie: an int32_t immediately precedes SMAP.
	 */
	smapsize = *((u_int32_t *)smapbase - 1);
	smapend = (struct bios_smap *)((uintptr_t)smapbase + smapsize);

	for (smap = smapbase; smap < smapend; smap++)
		if (!add_smap_entry(smap, physmap, physmap_idxp))
			break;
}

static void
basemem_setup(void)
{
	pt_entry_t *pte;
	int i;

	if (basemem > 640) {
		printf("Preposterous BIOS basemem of %uK, truncating to 640K\n",
			basemem);
		basemem = 640;
	}

	/*
	 * Map pages between basemem and ISA_HOLE_START, if any, r/w into
	 * the vm86 page table so that vm86 can scribble on them using
	 * the vm86 map too.  XXX: why 2 ways for this and only 1 way for
	 * page 0, at least as initialized here?
	 */
	pte = (pt_entry_t *)vm86paddr;
	for (i = basemem / 4; i < 160; i++)
		pte[i] = (i << PAGE_SHIFT) | PG_V | PG_RW | PG_U;
}

/*
 * Populate the (physmap) array with base/bound pairs describing the
 * available physical memory in the system, then test this memory and
 * build the phys_avail array describing the actually-available memory.
 *
 * If we cannot accurately determine the physical memory map, then use
 * value from the 0xE801 call, and failing that, the RTC.
 *
 * Total memory size may be set by the kernel environment variable
 * hw.physmem or the compile-time define MAXMEM.
 *
 * XXX first should be vm_paddr_t.
 */
static void
getmemsize(int first)
{
	int has_smap, off, physmap_idx, pa_indx, da_indx;
	u_long memtest;
	vm_paddr_t physmap[PHYSMAP_SIZE];
	pt_entry_t *pte;
	quad_t dcons_addr, dcons_size, physmem_tunable;
	int hasbrokenint12, i, res;
	u_int extmem;
	struct vm86frame vmf;
	struct vm86context vmc;
	vm_paddr_t pa;
	struct bios_smap *smap, *smapbase;
	caddr_t kmdp;

	has_smap = 0;
	bzero(&vmf, sizeof(vmf));
	bzero(physmap, sizeof(physmap));
	basemem = 0;

	/*
	 * Tell the physical memory allocator about pages used to store
	 * the kernel and preloaded data.  See kmem_bootstrap_free().
	 */
	vm_phys_add_seg((vm_paddr_t)KERNLOAD, trunc_page(first));

	/*
	 * Check if the loader supplied an SMAP memory map.  If so,
	 * use that and do not make any VM86 calls.
	 */
	physmap_idx = 0;
	kmdp = preload_search_by_type("elf kernel");
	if (kmdp == NULL)
		kmdp = preload_search_by_type("elf32 kernel");
	smapbase = (struct bios_smap *)preload_search_info(kmdp,
	    MODINFO_METADATA | MODINFOMD_SMAP);
	if (smapbase != NULL) {
		add_smap_entries(smapbase, physmap, &physmap_idx);
		has_smap = 1;
		goto have_smap;
	}

	/*
	 * Some newer BIOSes have a broken INT 12H implementation
	 * which causes a kernel panic immediately.  In this case, we
	 * need use the SMAP to determine the base memory size.
	 */
	hasbrokenint12 = 0;
	TUNABLE_INT_FETCH("hw.hasbrokenint12", &hasbrokenint12);
	if (hasbrokenint12 == 0) {
		/* Use INT12 to determine base memory size. */
		vm86_intcall(0x12, &vmf);
		basemem = vmf.vmf_ax;
		basemem_setup();
	}

	/*
	 * Fetch the memory map with INT 15:E820.  Map page 1 R/W into
	 * the kernel page table so we can use it as a buffer.  The
	 * kernel will unmap this page later.
	 */
	vmc.npages = 0;
	smap = (void *)vm86_addpage(&vmc, 1, PMAP_MAP_LOW + ptoa(1));
	res = vm86_getptr(&vmc, (vm_offset_t)smap, &vmf.vmf_es, &vmf.vmf_di);
	KASSERT(res != 0, ("vm86_getptr() failed: address not found"));

	vmf.vmf_ebx = 0;
	do {
		vmf.vmf_eax = 0xE820;
		vmf.vmf_edx = SMAP_SIG;
		vmf.vmf_ecx = sizeof(struct bios_smap);
		i = vm86_datacall(0x15, &vmf, &vmc);
		if (i || vmf.vmf_eax != SMAP_SIG)
			break;
		has_smap = 1;
		if (!add_smap_entry(smap, physmap, &physmap_idx))
			break;
	} while (vmf.vmf_ebx != 0);

have_smap:
	/*
	 * If we didn't fetch the "base memory" size from INT12,
	 * figure it out from the SMAP (or just guess).
	 */
	if (basemem == 0) {
		for (i = 0; i <= physmap_idx; i += 2) {
			if (physmap[i] == 0x00000000) {
				basemem = physmap[i + 1] / 1024;
				break;
			}
		}

		/* XXX: If we couldn't find basemem from SMAP, just guess. */
		if (basemem == 0)
			basemem = 640;
		basemem_setup();
	}

	if (physmap[1] != 0)
		goto physmap_done;

	/*
	 * If we failed to find an SMAP, figure out the extended
	 * memory size.  We will then build a simple memory map with
	 * two segments, one for "base memory" and the second for
	 * "extended memory".  Note that "extended memory" starts at a
	 * physical address of 1MB and that both basemem and extmem
	 * are in units of 1KB.
	 *
	 * First, try to fetch the extended memory size via INT 15:E801.
	 */
	vmf.vmf_ax = 0xE801;
	if (vm86_intcall(0x15, &vmf) == 0) {
		extmem = vmf.vmf_cx + vmf.vmf_dx * 64;
	} else {
		/*
		 * If INT15:E801 fails, this is our last ditch effort
		 * to determine the extended memory size.  Currently
		 * we prefer the RTC value over INT15:88.
		 */
#if 0
		vmf.vmf_ah = 0x88;
		vm86_intcall(0x15, &vmf);
		extmem = vmf.vmf_ax;
#else
		extmem = rtcin(RTC_EXTLO) + (rtcin(RTC_EXTHI) << 8);
#endif
	}

	/*
	 * Special hack for chipsets that still remap the 384k hole when
	 * there's 16MB of memory - this really confuses people that
	 * are trying to use bus mastering ISA controllers with the
	 * "16MB limit"; they only have 16MB, but the remapping puts
	 * them beyond the limit.
	 *
	 * If extended memory is between 15-16MB (16-17MB phys address range),
	 *	chop it to 15MB.
	 */
	if ((extmem > 15 * 1024) && (extmem < 16 * 1024))
		extmem = 15 * 1024;

	physmap[0] = 0;
	physmap[1] = basemem * 1024;
	physmap_idx = 2;
	physmap[physmap_idx] = 0x100000;
	physmap[physmap_idx + 1] = physmap[physmap_idx] + extmem * 1024;

physmap_done:
	/*
	 * Now, physmap contains a map of physical memory.
	 */

#ifdef SMP
	/* make hole for AP bootstrap code */
	alloc_ap_trampoline(physmap, &physmap_idx);
#endif

	/*
	 * Maxmem isn't the "maximum memory", it's one larger than the
	 * highest page of the physical address space.  It should be
	 * called something like "Maxphyspage".  We may adjust this
	 * based on ``hw.physmem'' and the results of the memory test.
	 *
	 * This is especially confusing when it is much larger than the
	 * memory size and is displayed as "realmem".
	 */
	Maxmem = atop(physmap[physmap_idx + 1]);

#ifdef MAXMEM
	Maxmem = MAXMEM / 4;
#endif

	if (TUNABLE_QUAD_FETCH("hw.physmem", &physmem_tunable))
		Maxmem = atop(physmem_tunable);

	/*
	 * If we have an SMAP, don't allow MAXMEM or hw.physmem to extend
	 * the amount of memory in the system.
	 */
	if (has_smap && Maxmem > atop(physmap[physmap_idx + 1]))
		Maxmem = atop(physmap[physmap_idx + 1]);

	/*
	 * By default enable the memory test on real hardware, and disable
	 * it if we appear to be running in a VM.  This avoids touching all
	 * pages unnecessarily, which doesn't matter on real hardware but is
	 * bad for shared VM hosts.  Use a general name so that
	 * one could eventually do more with the code than just disable it.
	 */
	memtest = (vm_guest > VM_GUEST_NO) ? 0 : 1;
	TUNABLE_ULONG_FETCH("hw.memtest.tests", &memtest);

	if (atop(physmap[physmap_idx + 1]) != Maxmem &&
	    (boothowto & RB_VERBOSE))
		printf("Physical memory use set to %ldK\n", Maxmem * 4);

	/*
	 * If Maxmem has been increased beyond what the system has detected,
	 * extend the last memory segment to the new limit.
	 */
	if (atop(physmap[physmap_idx + 1]) < Maxmem)
		physmap[physmap_idx + 1] = ptoa((vm_paddr_t)Maxmem);

	/* call pmap initialization to make new kernel address space */
	pmap_bootstrap(first);

	/*
	 * Size up each available chunk of physical memory.
	 */
	physmap[0] = PAGE_SIZE;		/* mask off page 0 */
	pa_indx = 0;
	da_indx = 1;
	phys_avail[pa_indx++] = physmap[0];
	phys_avail[pa_indx] = physmap[0];
	dump_avail[da_indx] = physmap[0];
	pte = CMAP3;

	/*
	 * Get dcons buffer address
	 */
	if (getenv_quad("dcons.addr", &dcons_addr) == 0 ||
	    getenv_quad("dcons.size", &dcons_size) == 0)
		dcons_addr = 0;

	/*
	 * physmap is in bytes, so when converting to page boundaries,
	 * round up the start address and round down the end address.
	 */
	for (i = 0; i <= physmap_idx; i += 2) {
		vm_paddr_t end;

		end = ptoa((vm_paddr_t)Maxmem);
		if (physmap[i + 1] < end)
			end = trunc_page(physmap[i + 1]);
		for (pa = round_page(physmap[i]); pa < end; pa += PAGE_SIZE) {
			int tmp, page_bad, full;
			int *ptr = (int *)CADDR3;

			full = FALSE;
			/*
			 * block out kernel memory as not available.
			 */
			if (pa >= KERNLOAD && pa < first)
				goto do_dump_avail;

			/*
			 * block out dcons buffer
			 */
			if (dcons_addr > 0
			    && pa >= trunc_page(dcons_addr)
			    && pa < dcons_addr + dcons_size)
				goto do_dump_avail;

			page_bad = FALSE;
			if (memtest == 0)
				goto skip_memtest;

			/*
			 * map page into kernel: valid, read/write,non-cacheable
			 */
			*pte = pa | PG_V | PG_RW | PG_N;
			invltlb();

			tmp = *(int *)ptr;
			/*
			 * Test for alternating 1's and 0's
			 */
			*(volatile int *)ptr = 0xaaaaaaaa;
			if (*(volatile int *)ptr != 0xaaaaaaaa)
				page_bad = TRUE;
			/*
			 * Test for alternating 0's and 1's
			 */
			*(volatile int *)ptr = 0x55555555;
			if (*(volatile int *)ptr != 0x55555555)
				page_bad = TRUE;
			/*
			 * Test for all 1's
			 */
			*(volatile int *)ptr = 0xffffffff;
			if (*(volatile int *)ptr != 0xffffffff)
				page_bad = TRUE;
			/*
			 * Test for all 0's
			 */
			*(volatile int *)ptr = 0x0;
			if (*(volatile int *)ptr != 0x0)
				page_bad = TRUE;
			/*
			 * Restore original value.
			 */
			*(int *)ptr = tmp;

skip_memtest:
			/*
			 * Adjust array of valid/good pages.
			 */
			if (page_bad == TRUE)
				continue;
			/*
			 * If this good page is a continuation of the
			 * previous set of good pages, then just increase
			 * the end pointer. Otherwise start a new chunk.
			 * Note that "end" points one higher than end,
			 * making the range >= start and < end.
			 * If we're also doing a speculative memory
			 * test and we at or past the end, bump up Maxmem
			 * so that we keep going. The first bad page
			 * will terminate the loop.
			 */
			if (phys_avail[pa_indx] == pa) {
				phys_avail[pa_indx] += PAGE_SIZE;
			} else {
				pa_indx++;
				if (pa_indx == PHYS_AVAIL_ARRAY_END) {
					printf(
		"Too many holes in the physical address space, giving up\n");
					pa_indx--;
					full = TRUE;
					goto do_dump_avail;
				}
				phys_avail[pa_indx++] = pa;	/* start */
				phys_avail[pa_indx] = pa + PAGE_SIZE; /* end */
			}
			physmem++;
do_dump_avail:
			if (dump_avail[da_indx] == pa) {
				dump_avail[da_indx] += PAGE_SIZE;
			} else {
				da_indx++;
				if (da_indx == DUMP_AVAIL_ARRAY_END) {
					da_indx--;
					goto do_next;
				}
				dump_avail[da_indx++] = pa;	/* start */
				dump_avail[da_indx] = pa + PAGE_SIZE; /* end */
			}
do_next:
			if (full)
				break;
		}
	}
	*pte = 0;
	invltlb();

	/*
	 * XXX
	 * The last chunk must contain at least one page plus the message
	 * buffer to avoid complicating other code (message buffer address
	 * calculation, etc.).
	 */
	while (phys_avail[pa_indx - 1] + PAGE_SIZE +
	    round_page(msgbufsize) >= phys_avail[pa_indx]) {
		physmem -= atop(phys_avail[pa_indx] - phys_avail[pa_indx - 1]);
		phys_avail[pa_indx--] = 0;
		phys_avail[pa_indx--] = 0;
	}

	Maxmem = atop(phys_avail[pa_indx]);

	/* Trim off space for the message buffer. */
	phys_avail[pa_indx] -= round_page(msgbufsize);

	/* Map the message buffer. */
	for (off = 0; off < round_page(msgbufsize); off += PAGE_SIZE)
		pmap_kenter((vm_offset_t)msgbufp + off, phys_avail[pa_indx] +
		    off);
}

static void
i386_kdb_init(void)
{
#ifdef DDB
	db_fetch_ksymtab(bootinfo.bi_symtab, bootinfo.bi_esymtab);
#endif
	kdb_init();
#ifdef KDB
	if (boothowto & RB_KDB)
		kdb_enter(KDB_WHY_BOOTFLAGS, "Boot flags requested debugger");
#endif
}

static void
fixup_idt(void)
{
	struct gate_descriptor *ip;
	uintptr_t off;
	int x;

	for (x = 0; x < NIDT; x++) {
		ip = &idt[x];
		if (ip->gd_type != SDT_SYS386IGT &&
		    ip->gd_type != SDT_SYS386TGT)
			continue;
		off = ip->gd_looffset + (((u_int)ip->gd_hioffset) << 16);
		KASSERT(off >= (uintptr_t)start_exceptions &&
		    off < (uintptr_t)end_exceptions,
		    ("IDT[%d] type %d off %#x", x, ip->gd_type, off));
		off += setidt_disp;
		MPASS(off >= PMAP_TRM_MIN_ADDRESS &&
		    off < PMAP_TRM_MAX_ADDRESS);
		ip->gd_looffset = off;
		ip->gd_hioffset = off >> 16;
	}
}

static void
i386_setidt1(void)
{
	int x;

	/* exceptions */
	for (x = 0; x < NIDT; x++)
		setidt(x, &IDTVEC(rsvd), SDT_SYS386IGT, SEL_KPL,
		    GSEL(GCODE_SEL, SEL_KPL));
	setidt(IDT_DE, &IDTVEC(div), SDT_SYS386IGT, SEL_KPL,
	    GSEL(GCODE_SEL, SEL_KPL));
	setidt(IDT_DB, &IDTVEC(dbg), SDT_SYS386IGT, SEL_KPL,
	    GSEL(GCODE_SEL, SEL_KPL));
	setidt(IDT_NMI, &IDTVEC(nmi), SDT_SYS386IGT, SEL_KPL,
	    GSEL(GCODE_SEL, SEL_KPL));
	setidt(IDT_BP, &IDTVEC(bpt), SDT_SYS386IGT, SEL_UPL,
	    GSEL(GCODE_SEL, SEL_KPL));
	setidt(IDT_OF, &IDTVEC(ofl), SDT_SYS386IGT, SEL_UPL,
	    GSEL(GCODE_SEL, SEL_KPL));
	setidt(IDT_BR, &IDTVEC(bnd), SDT_SYS386IGT, SEL_KPL,
	    GSEL(GCODE_SEL, SEL_KPL));
	setidt(IDT_UD, &IDTVEC(ill), SDT_SYS386IGT, SEL_KPL,
	    GSEL(GCODE_SEL, SEL_KPL));
	setidt(IDT_NM, &IDTVEC(dna), SDT_SYS386IGT, SEL_KPL,
	    GSEL(GCODE_SEL, SEL_KPL));
	setidt(IDT_DF, 0, SDT_SYSTASKGT, SEL_KPL, GSEL(GPANIC_SEL,
	    SEL_KPL));
	setidt(IDT_FPUGP, &IDTVEC(fpusegm), SDT_SYS386IGT,
	    SEL_KPL, GSEL(GCODE_SEL, SEL_KPL));
	setidt(IDT_TS, &IDTVEC(tss), SDT_SYS386IGT, SEL_KPL,
	    GSEL(GCODE_SEL, SEL_KPL));
	setidt(IDT_NP, &IDTVEC(missing), SDT_SYS386IGT, SEL_KPL,
	    GSEL(GCODE_SEL, SEL_KPL));
	setidt(IDT_SS, &IDTVEC(stk), SDT_SYS386IGT, SEL_KPL,
	    GSEL(GCODE_SEL, SEL_KPL));
	setidt(IDT_GP, &IDTVEC(prot), SDT_SYS386IGT, SEL_KPL,
	    GSEL(GCODE_SEL, SEL_KPL));
	setidt(IDT_PF, &IDTVEC(page), SDT_SYS386IGT, SEL_KPL,
	    GSEL(GCODE_SEL, SEL_KPL));
	setidt(IDT_MF, &IDTVEC(fpu), SDT_SYS386IGT, SEL_KPL,
	    GSEL(GCODE_SEL, SEL_KPL));
	setidt(IDT_AC, &IDTVEC(align), SDT_SYS386IGT, SEL_KPL,
	    GSEL(GCODE_SEL, SEL_KPL));
	setidt(IDT_MC, &IDTVEC(mchk), SDT_SYS386IGT, SEL_KPL,
	    GSEL(GCODE_SEL, SEL_KPL));
	setidt(IDT_XF, &IDTVEC(xmm), SDT_SYS386IGT, SEL_KPL,
	    GSEL(GCODE_SEL, SEL_KPL));
	setidt(IDT_SYSCALL, &IDTVEC(int0x80_syscall),
	    SDT_SYS386IGT, SEL_UPL, GSEL(GCODE_SEL, SEL_KPL));
#ifdef KDTRACE_HOOKS
	setidt(IDT_DTRACE_RET, &IDTVEC(dtrace_ret),
	    SDT_SYS386IGT, SEL_UPL, GSEL(GCODE_SEL, SEL_KPL));
#endif
#ifdef XENHVM
	setidt(IDT_EVTCHN, &IDTVEC(xen_intr_upcall),
	    SDT_SYS386IGT, SEL_KPL, GSEL(GCODE_SEL, SEL_KPL));
#endif
}

static void
i386_setidt2(void)
{

	setidt(IDT_UD, &IDTVEC(ill), SDT_SYS386IGT, SEL_KPL,
	    GSEL(GCODE_SEL, SEL_KPL));
	setidt(IDT_GP, &IDTVEC(prot), SDT_SYS386IGT, SEL_KPL,
	    GSEL(GCODE_SEL, SEL_KPL));
}

#if defined(DEV_ISA) && !defined(DEV_ATPIC)
static void
i386_setidt3(void)
{

	setidt(IDT_IO_INTS + 7, IDTVEC(spuriousint),
	    SDT_SYS386IGT, SEL_KPL, GSEL(GCODE_SEL, SEL_KPL));
	setidt(IDT_IO_INTS + 15, IDTVEC(spuriousint),
	    SDT_SYS386IGT, SEL_KPL, GSEL(GCODE_SEL, SEL_KPL));
}
#endif

register_t
init386(int first)
{
	struct region_descriptor r_gdt, r_idt;	/* table descriptors */
	int gsel_tss, metadata_missing, x, pa;
	struct pcpu *pc;
	struct xstate_hdr *xhdr;
	caddr_t kmdp;
	vm_offset_t addend;
	size_t ucode_len;
	int late_console;

	thread0.td_kstack = proc0kstack;
	thread0.td_kstack_pages = TD0_KSTACK_PAGES;

	/*
 	 * This may be done better later if it gets more high level
 	 * components in it. If so just link td->td_proc here.
	 */
	proc_linkup0(&proc0, &thread0);

	if (bootinfo.bi_modulep) {
		metadata_missing = 0;
		addend = (vm_paddr_t)bootinfo.bi_modulep < KERNBASE ?
		    PMAP_MAP_LOW : 0;
		preload_metadata = (caddr_t)bootinfo.bi_modulep + addend;
		preload_bootstrap_relocate(addend);
	} else {
		metadata_missing = 1;
	}

	if (bootinfo.bi_envp != 0) {
		addend = (vm_paddr_t)bootinfo.bi_envp < KERNBASE ?
		    PMAP_MAP_LOW : 0;
		init_static_kenv((char *)bootinfo.bi_envp + addend, 0);
	} else {
		init_static_kenv(NULL, 0);
	}

	/*
	 * Re-evaluate CPU features if we loaded a microcode update.
	 */
	ucode_len = ucode_load_bsp(first);
	if (ucode_len != 0) {
		identify_cpu();
		first = roundup2(first + ucode_len, PAGE_SIZE);
	}

	identify_hypervisor();

	/* Init basic tunables, hz etc */
	init_param1();

	/*
	 * Make gdt memory segments.  All segments cover the full 4GB
	 * of address space and permissions are enforced at page level.
	 */
	gdt_segs[GCODE_SEL].ssd_limit = atop(0 - 1);
	gdt_segs[GDATA_SEL].ssd_limit = atop(0 - 1);
	gdt_segs[GUCODE_SEL].ssd_limit = atop(0 - 1);
	gdt_segs[GUDATA_SEL].ssd_limit = atop(0 - 1);
	gdt_segs[GUFS_SEL].ssd_limit = atop(0 - 1);
	gdt_segs[GUGS_SEL].ssd_limit = atop(0 - 1);

	pc = &__pcpu[0];
	gdt_segs[GPRIV_SEL].ssd_limit = atop(0 - 1);
	gdt_segs[GPRIV_SEL].ssd_base = (int)pc;
	gdt_segs[GPROC0_SEL].ssd_base = (int)&common_tss0;

	for (x = 0; x < NGDT; x++)
		ssdtosd(&gdt_segs[x], &gdt0[x].sd);

	r_gdt.rd_limit = NGDT * sizeof(gdt0[0]) - 1;
	r_gdt.rd_base =  (int)gdt0;
	mtx_init(&dt_lock, "descriptor tables", NULL, MTX_SPIN);
	lgdt(&r_gdt);

	pcpu_init(pc, 0, sizeof(struct pcpu));
	for (pa = first; pa < first + DPCPU_SIZE; pa += PAGE_SIZE)
		pmap_kenter(pa, pa);
	dpcpu_init((void *)first, 0);
	first += DPCPU_SIZE;
	PCPU_SET(prvspace, pc);
	PCPU_SET(curthread, &thread0);
	/* Non-late cninit() and printf() can be moved up to here. */

	/*
	 * Initialize mutexes.
	 *
	 * icu_lock: in order to allow an interrupt to occur in a critical
	 * 	     section, to set pcpu->ipending (etc...) properly, we
	 *	     must be able to get the icu lock, so it can't be
	 *	     under witness.
	 */
	mutex_init();
	mtx_init(&icu_lock, "icu", NULL, MTX_SPIN | MTX_NOWITNESS | MTX_NOPROFILE);

	i386_setidt1();

	r_idt.rd_limit = sizeof(idt0) - 1;
	r_idt.rd_base = (int) idt;
	lidt(&r_idt);

	/*
	 * Initialize the clock before the console so that console
	 * initialization can use DELAY().
	 */
	clock_init();

	finishidentcpu();	/* Final stage of CPU initialization */
	i386_setidt2();
	initializecpu();	/* Initialize CPU registers */
	initializecpucache();

	/* pointer to selector slot for %fs/%gs */
	PCPU_SET(fsgs_gdt, &gdt[GUFS_SEL].sd);

	/* Initialize the tss (except for the final esp0) early for vm86. */
	common_tss0.tss_esp0 = thread0.td_kstack + thread0.td_kstack_pages *
	    PAGE_SIZE - VM86_STACK_SPACE;
	common_tss0.tss_ss0 = GSEL(GDATA_SEL, SEL_KPL);
	common_tss0.tss_ioopt = sizeof(struct i386tss) << 16;
	gsel_tss = GSEL(GPROC0_SEL, SEL_KPL);
	PCPU_SET(tss_gdt, &gdt[GPROC0_SEL].sd);
	PCPU_SET(common_tssd, *PCPU_GET(tss_gdt));
	ltr(gsel_tss);

	/* Initialize the PIC early for vm86 calls. */
#ifdef DEV_ISA
#ifdef DEV_ATPIC
	elcr_probe();
	atpic_startup();
#else
	/* Reset and mask the atpics and leave them shut down. */
	atpic_reset();

	/*
	 * Point the ICU spurious interrupt vectors at the APIC spurious
	 * interrupt handler.
	 */
	i386_setidt3();
#endif
#endif

	/*
	 * The console and kdb should be initialized even earlier than here,
	 * but some console drivers don't work until after getmemsize().
	 * Default to late console initialization to support these drivers.
	 * This loses mainly printf()s in getmemsize() and early debugging.
	 */
	late_console = 1;
	TUNABLE_INT_FETCH("debug.late_console", &late_console);
	if (!late_console) {
		cninit();
		i386_kdb_init();
	}

	kmdp = preload_search_by_type("elf kernel");
	link_elf_ireloc(kmdp);

	vm86_initialize();
	getmemsize(first);
	init_param2(physmem);

	/* now running on new page tables, configured,and u/iom is accessible */

	if (late_console)
		cninit();

	if (metadata_missing)
		printf("WARNING: loader(8) metadata is missing!\n");

	if (late_console)
		i386_kdb_init();

	msgbufinit(msgbufp, msgbufsize);
	npxinit(true);
	/*
	 * Set up thread0 pcb after npxinit calculated pcb + fpu save
	 * area size.  Zero out the extended state header in fpu save
	 * area.
	 */
	thread0.td_pcb = get_pcb_td(&thread0);
	thread0.td_pcb->pcb_save = get_pcb_user_save_td(&thread0);
	bzero(get_pcb_user_save_td(&thread0), cpu_max_ext_state_size);
	if (use_xsave) {
		xhdr = (struct xstate_hdr *)(get_pcb_user_save_td(&thread0) +
		    1);
		xhdr->xstate_bv = xsave_mask;
	}
	PCPU_SET(curpcb, thread0.td_pcb);
	/* Move esp0 in the tss to its final place. */
	/* Note: -16 is so we can grow the trapframe if we came from vm86 */
	common_tss0.tss_esp0 = (vm_offset_t)thread0.td_pcb - VM86_STACK_SPACE;
	PCPU_SET(kesp0, common_tss0.tss_esp0);
	gdt[GPROC0_SEL].sd.sd_type = SDT_SYS386TSS;	/* clear busy bit */
	ltr(gsel_tss);

	/* transfer to user mode */

	_ucodesel = GSEL(GUCODE_SEL, SEL_UPL);
	_udatasel = GSEL(GUDATA_SEL, SEL_UPL);

	/* setup proc 0's pcb */
	thread0.td_pcb->pcb_flags = 0;
#if defined(PAE) || defined(PAE_TABLES)
	thread0.td_pcb->pcb_cr3 = (int)IdlePDPT;
#else
	thread0.td_pcb->pcb_cr3 = (int)IdlePTD;
#endif
	thread0.td_pcb->pcb_ext = 0;
	thread0.td_frame = &proc0_tf;

	cpu_probe_amdc1e();

#ifdef FDT
	x86_init_fdt();
#endif

	/* Location of kernel stack for locore */
	return ((register_t)thread0.td_pcb);
}

static void
machdep_init_trampoline(void)
{
	struct region_descriptor r_gdt, r_idt;
	struct i386tss *tss;
	char *copyout_buf, *trampoline, *tramp_stack_base;
	int x;

	gdt = pmap_trm_alloc(sizeof(union descriptor) * NGDT * mp_ncpus,
	    M_NOWAIT | M_ZERO);
	bcopy(gdt0, gdt, sizeof(union descriptor) * NGDT);
	r_gdt.rd_limit = NGDT * sizeof(gdt[0]) - 1;
	r_gdt.rd_base = (int)gdt;
	lgdt(&r_gdt);

	tss = pmap_trm_alloc(sizeof(struct i386tss) * mp_ncpus,
	    M_NOWAIT | M_ZERO);
	bcopy(&common_tss0, tss, sizeof(struct i386tss));
	gdt[GPROC0_SEL].sd.sd_lobase = (int)tss;
	gdt[GPROC0_SEL].sd.sd_hibase = (u_int)tss >> 24;
	gdt[GPROC0_SEL].sd.sd_type = SDT_SYS386TSS;

	PCPU_SET(fsgs_gdt, &gdt[GUFS_SEL].sd);
	PCPU_SET(tss_gdt, &gdt[GPROC0_SEL].sd);
	PCPU_SET(common_tssd, *PCPU_GET(tss_gdt));
	PCPU_SET(common_tssp, tss);
	ltr(GSEL(GPROC0_SEL, SEL_KPL));

	trampoline = pmap_trm_alloc(end_exceptions - start_exceptions,
	    M_NOWAIT);
	bcopy(start_exceptions, trampoline, end_exceptions - start_exceptions);
	tramp_stack_base = pmap_trm_alloc(TRAMP_STACK_SZ, M_NOWAIT);
	PCPU_SET(trampstk, (uintptr_t)tramp_stack_base + TRAMP_STACK_SZ -
	    VM86_STACK_SPACE);
	tss[0].tss_esp0 = PCPU_GET(trampstk);

	idt = pmap_trm_alloc(sizeof(idt0), M_NOWAIT | M_ZERO);
	bcopy(idt0, idt, sizeof(idt0));

	/* Re-initialize new IDT since the handlers were relocated */
	setidt_disp = trampoline - start_exceptions;
	fixup_idt();

	r_idt.rd_limit = sizeof(struct gate_descriptor) * NIDT - 1;
	r_idt.rd_base = (int)idt;
	lidt(&r_idt);

	/* dblfault TSS */
	dblfault_tss = pmap_trm_alloc(sizeof(struct i386tss), M_NOWAIT | M_ZERO);
	dblfault_stack = pmap_trm_alloc(PAGE_SIZE, M_NOWAIT);
	dblfault_tss->tss_esp = dblfault_tss->tss_esp0 =
	    dblfault_tss->tss_esp1 = dblfault_tss->tss_esp2 =
	    (int)dblfault_stack + PAGE_SIZE;
	dblfault_tss->tss_ss = dblfault_tss->tss_ss0 = dblfault_tss->tss_ss1 =
	    dblfault_tss->tss_ss2 = GSEL(GDATA_SEL, SEL_KPL);
#if defined(PAE) || defined(PAE_TABLES)
	dblfault_tss->tss_cr3 = (int)IdlePDPT;
#else
	dblfault_tss->tss_cr3 = (int)IdlePTD;
#endif
	dblfault_tss->tss_eip = (int)dblfault_handler;
	dblfault_tss->tss_eflags = PSL_KERNEL;
	dblfault_tss->tss_ds = dblfault_tss->tss_es =
	    dblfault_tss->tss_gs = GSEL(GDATA_SEL, SEL_KPL);
	dblfault_tss->tss_fs = GSEL(GPRIV_SEL, SEL_KPL);
	dblfault_tss->tss_cs = GSEL(GCODE_SEL, SEL_KPL);
	dblfault_tss->tss_ldt = GSEL(GLDT_SEL, SEL_KPL);
	gdt[GPANIC_SEL].sd.sd_lobase = (int)dblfault_tss;
	gdt[GPANIC_SEL].sd.sd_hibase = (u_int)dblfault_tss >> 24;

	/* make ldt memory segments */
	ldt = pmap_trm_alloc(sizeof(union descriptor) * NLDT,
	    M_NOWAIT | M_ZERO);
	gdt[GLDT_SEL].sd.sd_lobase = (int)ldt;
	gdt[GLDT_SEL].sd.sd_hibase = (u_int)ldt >> 24;
	ldt_segs[LUCODE_SEL].ssd_limit = atop(0 - 1);
	ldt_segs[LUDATA_SEL].ssd_limit = atop(0 - 1);
	for (x = 0; x < nitems(ldt_segs); x++)
		ssdtosd(&ldt_segs[x], &ldt[x].sd);

	_default_ldt = GSEL(GLDT_SEL, SEL_KPL);
	lldt(_default_ldt);
	PCPU_SET(currentldt, _default_ldt);

	copyout_buf = pmap_trm_alloc(TRAMP_COPYOUT_SZ, M_NOWAIT);
	PCPU_SET(copyout_buf, copyout_buf);
	copyout_init_tramp();
}
SYSINIT(vm_mem, SI_SUB_VM, SI_ORDER_SECOND, machdep_init_trampoline, NULL);

#ifdef COMPAT_43
static void
i386_setup_lcall_gate(void)
{
	struct sysentvec *sv;
	struct user_segment_descriptor desc;
	u_int lcall_addr;

	sv = &elf32_freebsd_sysvec;
	lcall_addr = (uintptr_t)sv->sv_psstrings - sz_lcall_tramp;

	bzero(&desc, sizeof(desc));
	desc.sd_type = SDT_MEMERA;
	desc.sd_dpl = SEL_UPL;
	desc.sd_p = 1;
	desc.sd_def32 = 1;
	desc.sd_gran = 1;
	desc.sd_lolimit = 0xffff;
	desc.sd_hilimit = 0xf;
	desc.sd_lobase = lcall_addr;
	desc.sd_hibase = lcall_addr >> 24;
	bcopy(&desc, &ldt[LSYS5CALLS_SEL], sizeof(desc));
}
SYSINIT(elf32, SI_SUB_EXEC, SI_ORDER_ANY, i386_setup_lcall_gate, NULL);
#endif

void
cpu_pcpu_init(struct pcpu *pcpu, int cpuid, size_t size)
{

	pcpu->pc_acpi_id = 0xffffffff;
}

static int
smap_sysctl_handler(SYSCTL_HANDLER_ARGS)
{
	struct bios_smap *smapbase;
	struct bios_smap_xattr smap;
	caddr_t kmdp;
	uint32_t *smapattr;
	int count, error, i;

	/* Retrieve the system memory map from the loader. */
	kmdp = preload_search_by_type("elf kernel");
	if (kmdp == NULL)
		kmdp = preload_search_by_type("elf32 kernel");
	smapbase = (struct bios_smap *)preload_search_info(kmdp,
	    MODINFO_METADATA | MODINFOMD_SMAP);
	if (smapbase == NULL)
		return (0);
	smapattr = (uint32_t *)preload_search_info(kmdp,
	    MODINFO_METADATA | MODINFOMD_SMAP_XATTR);
	count = *((u_int32_t *)smapbase - 1) / sizeof(*smapbase);
	error = 0;
	for (i = 0; i < count; i++) {
		smap.base = smapbase[i].base;
		smap.length = smapbase[i].length;
		smap.type = smapbase[i].type;
		if (smapattr != NULL)
			smap.xattr = smapattr[i];
		else
			smap.xattr = 0;
		error = SYSCTL_OUT(req, &smap, sizeof(smap));
	}
	return (error);
}
SYSCTL_PROC(_machdep, OID_AUTO, smap, CTLTYPE_OPAQUE|CTLFLAG_RD, NULL, 0,
    smap_sysctl_handler, "S,bios_smap_xattr", "Raw BIOS SMAP data");

void
spinlock_enter(void)
{
	struct thread *td;
	register_t flags;

	td = curthread;
	if (td->td_md.md_spinlock_count == 0) {
		flags = intr_disable();
		td->td_md.md_spinlock_count = 1;
		td->td_md.md_saved_flags = flags;
	} else
		td->td_md.md_spinlock_count++;
	critical_enter();
}

void
spinlock_exit(void)
{
	struct thread *td;
	register_t flags;

	td = curthread;
	critical_exit();
	flags = td->td_md.md_saved_flags;
	td->td_md.md_spinlock_count--;
	if (td->td_md.md_spinlock_count == 0)
		intr_restore(flags);
}

#if defined(I586_CPU) && !defined(NO_F00F_HACK)
static void f00f_hack(void *unused);
SYSINIT(f00f_hack, SI_SUB_INTRINSIC, SI_ORDER_FIRST, f00f_hack, NULL);

static void
f00f_hack(void *unused)
{
	struct region_descriptor r_idt;
	struct gate_descriptor *new_idt;
	vm_offset_t tmp;

	if (!has_f00f_bug)
		return;

	GIANT_REQUIRED;

	printf("Intel Pentium detected, installing workaround for F00F bug\n");

	tmp = (vm_offset_t)pmap_trm_alloc(PAGE_SIZE * 3, M_NOWAIT | M_ZERO);
	if (tmp == 0)
		panic("kmem_malloc returned 0");
	tmp = round_page(tmp);

	/* Put the problematic entry (#6) at the end of the lower page. */
	new_idt = (struct gate_descriptor *)
	    (tmp + PAGE_SIZE - 7 * sizeof(struct gate_descriptor));
	bcopy(idt, new_idt, sizeof(idt0));
	r_idt.rd_base = (u_int)new_idt;
	r_idt.rd_limit = sizeof(idt0) - 1;
	lidt(&r_idt);
	/* SMP machines do not need the F00F hack. */
	idt = new_idt;
	pmap_protect(kernel_pmap, tmp, tmp + PAGE_SIZE, VM_PROT_READ);
}
#endif /* defined(I586_CPU) && !NO_F00F_HACK */

/*
 * Construct a PCB from a trapframe. This is called from kdb_trap() where
 * we want to start a backtrace from the function that caused us to enter
 * the debugger. We have the context in the trapframe, but base the trace
 * on the PCB. The PCB doesn't have to be perfect, as long as it contains
 * enough for a backtrace.
 */
void
makectx(struct trapframe *tf, struct pcb *pcb)
{

	pcb->pcb_edi = tf->tf_edi;
	pcb->pcb_esi = tf->tf_esi;
	pcb->pcb_ebp = tf->tf_ebp;
	pcb->pcb_ebx = tf->tf_ebx;
	pcb->pcb_eip = tf->tf_eip;
	pcb->pcb_esp = (ISPL(tf->tf_cs)) ? tf->tf_esp : (int)(tf + 1) - 8;
	pcb->pcb_gs = rgs();
}

int
ptrace_set_pc(struct thread *td, u_long addr)
{

	td->td_frame->tf_eip = addr;
	return (0);
}

int
ptrace_single_step(struct thread *td)
{

	PROC_LOCK_ASSERT(td->td_proc, MA_OWNED);
	if ((td->td_frame->tf_eflags & PSL_T) == 0) {
		td->td_frame->tf_eflags |= PSL_T;
		td->td_dbgflags |= TDB_STEP;
	}
	return (0);
}

int
ptrace_clear_single_step(struct thread *td)
{

	PROC_LOCK_ASSERT(td->td_proc, MA_OWNED);
	td->td_frame->tf_eflags &= ~PSL_T;
	td->td_dbgflags &= ~TDB_STEP;
	return (0);
}

int
fill_regs(struct thread *td, struct reg *regs)
{
	struct pcb *pcb;
	struct trapframe *tp;

	tp = td->td_frame;
	pcb = td->td_pcb;
	regs->r_gs = pcb->pcb_gs;
	return (fill_frame_regs(tp, regs));
}

int
fill_frame_regs(struct trapframe *tp, struct reg *regs)
{

	regs->r_fs = tp->tf_fs;
	regs->r_es = tp->tf_es;
	regs->r_ds = tp->tf_ds;
	regs->r_edi = tp->tf_edi;
	regs->r_esi = tp->tf_esi;
	regs->r_ebp = tp->tf_ebp;
	regs->r_ebx = tp->tf_ebx;
	regs->r_edx = tp->tf_edx;
	regs->r_ecx = tp->tf_ecx;
	regs->r_eax = tp->tf_eax;
	regs->r_eip = tp->tf_eip;
	regs->r_cs = tp->tf_cs;
	regs->r_eflags = tp->tf_eflags;
	regs->r_esp = tp->tf_esp;
	regs->r_ss = tp->tf_ss;
	regs->r_err = 0;
	regs->r_trapno = 0;
	return (0);
}

int
set_regs(struct thread *td, struct reg *regs)
{
	struct pcb *pcb;
	struct trapframe *tp;

	tp = td->td_frame;
	if (!EFL_SECURE(regs->r_eflags, tp->tf_eflags) ||
	    !CS_SECURE(regs->r_cs))
		return (EINVAL);
	pcb = td->td_pcb;
	tp->tf_fs = regs->r_fs;
	tp->tf_es = regs->r_es;
	tp->tf_ds = regs->r_ds;
	tp->tf_edi = regs->r_edi;
	tp->tf_esi = regs->r_esi;
	tp->tf_ebp = regs->r_ebp;
	tp->tf_ebx = regs->r_ebx;
	tp->tf_edx = regs->r_edx;
	tp->tf_ecx = regs->r_ecx;
	tp->tf_eax = regs->r_eax;
	tp->tf_eip = regs->r_eip;
	tp->tf_cs = regs->r_cs;
	tp->tf_eflags = regs->r_eflags;
	tp->tf_esp = regs->r_esp;
	tp->tf_ss = regs->r_ss;
	pcb->pcb_gs = regs->r_gs;
	return (0);
}

int
fill_fpregs(struct thread *td, struct fpreg *fpregs)
{

	KASSERT(td == curthread || TD_IS_SUSPENDED(td) ||
	    P_SHOULDSTOP(td->td_proc),
	    ("not suspended thread %p", td));
	npxgetregs(td);
	if (cpu_fxsr)
		npx_fill_fpregs_xmm(&get_pcb_user_save_td(td)->sv_xmm,
		    (struct save87 *)fpregs);
	else
		bcopy(&get_pcb_user_save_td(td)->sv_87, fpregs,
		    sizeof(*fpregs));
	return (0);
}

int
set_fpregs(struct thread *td, struct fpreg *fpregs)
{

	critical_enter();
	if (cpu_fxsr)
		npx_set_fpregs_xmm((struct save87 *)fpregs,
		    &get_pcb_user_save_td(td)->sv_xmm);
	else
		bcopy(fpregs, &get_pcb_user_save_td(td)->sv_87,
		    sizeof(*fpregs));
	npxuserinited(td);
	critical_exit();
	return (0);
}

/*
 * Get machine context.
 */
int
get_mcontext(struct thread *td, mcontext_t *mcp, int flags)
{
	struct trapframe *tp;
	struct segment_descriptor *sdp;

	tp = td->td_frame;

	PROC_LOCK(curthread->td_proc);
	mcp->mc_onstack = sigonstack(tp->tf_esp);
	PROC_UNLOCK(curthread->td_proc);
	mcp->mc_gs = td->td_pcb->pcb_gs;
	mcp->mc_fs = tp->tf_fs;
	mcp->mc_es = tp->tf_es;
	mcp->mc_ds = tp->tf_ds;
	mcp->mc_edi = tp->tf_edi;
	mcp->mc_esi = tp->tf_esi;
	mcp->mc_ebp = tp->tf_ebp;
	mcp->mc_isp = tp->tf_isp;
	mcp->mc_eflags = tp->tf_eflags;
	if (flags & GET_MC_CLEAR_RET) {
		mcp->mc_eax = 0;
		mcp->mc_edx = 0;
		mcp->mc_eflags &= ~PSL_C;
	} else {
		mcp->mc_eax = tp->tf_eax;
		mcp->mc_edx = tp->tf_edx;
	}
	mcp->mc_ebx = tp->tf_ebx;
	mcp->mc_ecx = tp->tf_ecx;
	mcp->mc_eip = tp->tf_eip;
	mcp->mc_cs = tp->tf_cs;
	mcp->mc_esp = tp->tf_esp;
	mcp->mc_ss = tp->tf_ss;
	mcp->mc_len = sizeof(*mcp);
	get_fpcontext(td, mcp, NULL, 0);
	sdp = &td->td_pcb->pcb_fsd;
	mcp->mc_fsbase = sdp->sd_hibase << 24 | sdp->sd_lobase;
	sdp = &td->td_pcb->pcb_gsd;
	mcp->mc_gsbase = sdp->sd_hibase << 24 | sdp->sd_lobase;
	mcp->mc_flags = 0;
	mcp->mc_xfpustate = 0;
	mcp->mc_xfpustate_len = 0;
	bzero(mcp->mc_spare2, sizeof(mcp->mc_spare2));
	return (0);
}

/*
 * Set machine context.
 *
 * However, we don't set any but the user modifiable flags, and we won't
 * touch the cs selector.
 */
int
set_mcontext(struct thread *td, mcontext_t *mcp)
{
	struct trapframe *tp;
	char *xfpustate;
	int eflags, ret;

	tp = td->td_frame;
	if (mcp->mc_len != sizeof(*mcp) ||
	    (mcp->mc_flags & ~_MC_FLAG_MASK) != 0)
		return (EINVAL);
	eflags = (mcp->mc_eflags & PSL_USERCHANGE) |
	    (tp->tf_eflags & ~PSL_USERCHANGE);
	if (mcp->mc_flags & _MC_HASFPXSTATE) {
		if (mcp->mc_xfpustate_len > cpu_max_ext_state_size -
		    sizeof(union savefpu))
			return (EINVAL);
		xfpustate = __builtin_alloca(mcp->mc_xfpustate_len);
		ret = copyin((void *)mcp->mc_xfpustate, xfpustate,
		    mcp->mc_xfpustate_len);
		if (ret != 0)
			return (ret);
	} else
		xfpustate = NULL;
	ret = set_fpcontext(td, mcp, xfpustate, mcp->mc_xfpustate_len);
	if (ret != 0)
		return (ret);
	tp->tf_fs = mcp->mc_fs;
	tp->tf_es = mcp->mc_es;
	tp->tf_ds = mcp->mc_ds;
	tp->tf_edi = mcp->mc_edi;
	tp->tf_esi = mcp->mc_esi;
	tp->tf_ebp = mcp->mc_ebp;
	tp->tf_ebx = mcp->mc_ebx;
	tp->tf_edx = mcp->mc_edx;
	tp->tf_ecx = mcp->mc_ecx;
	tp->tf_eax = mcp->mc_eax;
	tp->tf_eip = mcp->mc_eip;
	tp->tf_eflags = eflags;
	tp->tf_esp = mcp->mc_esp;
	tp->tf_ss = mcp->mc_ss;
	td->td_pcb->pcb_gs = mcp->mc_gs;
	return (0);
}

static void
get_fpcontext(struct thread *td, mcontext_t *mcp, char *xfpusave,
    size_t xfpusave_len)
{
	size_t max_len, len;

	mcp->mc_ownedfp = npxgetregs(td);
	bcopy(get_pcb_user_save_td(td), &mcp->mc_fpstate[0],
	    sizeof(mcp->mc_fpstate));
	mcp->mc_fpformat = npxformat();
	if (!use_xsave || xfpusave_len == 0)
		return;
	max_len = cpu_max_ext_state_size - sizeof(union savefpu);
	len = xfpusave_len;
	if (len > max_len) {
		len = max_len;
		bzero(xfpusave + max_len, len - max_len);
	}
	mcp->mc_flags |= _MC_HASFPXSTATE;
	mcp->mc_xfpustate_len = len;
	bcopy(get_pcb_user_save_td(td) + 1, xfpusave, len);
}

static int
set_fpcontext(struct thread *td, mcontext_t *mcp, char *xfpustate,
    size_t xfpustate_len)
{
	int error;

	if (mcp->mc_fpformat == _MC_FPFMT_NODEV)
		return (0);
	else if (mcp->mc_fpformat != _MC_FPFMT_387 &&
	    mcp->mc_fpformat != _MC_FPFMT_XMM)
		return (EINVAL);
	else if (mcp->mc_ownedfp == _MC_FPOWNED_NONE) {
		/* We don't care what state is left in the FPU or PCB. */
		fpstate_drop(td);
		error = 0;
	} else if (mcp->mc_ownedfp == _MC_FPOWNED_FPU ||
	    mcp->mc_ownedfp == _MC_FPOWNED_PCB) {
		error = npxsetregs(td, (union savefpu *)&mcp->mc_fpstate,
		    xfpustate, xfpustate_len);
	} else
		return (EINVAL);
	return (error);
}

static void
fpstate_drop(struct thread *td)
{

	KASSERT(PCB_USER_FPU(td->td_pcb), ("fpstate_drop: kernel-owned fpu"));
	critical_enter();
	if (PCPU_GET(fpcurthread) == td)
		npxdrop();
	/*
	 * XXX force a full drop of the npx.  The above only drops it if we
	 * owned it.  npxgetregs() has the same bug in the !cpu_fxsr case.
	 *
	 * XXX I don't much like npxgetregs()'s semantics of doing a full
	 * drop.  Dropping only to the pcb matches fnsave's behaviour.
	 * We only need to drop to !PCB_INITDONE in sendsig().  But
	 * sendsig() is the only caller of npxgetregs()... perhaps we just
	 * have too many layers.
	 */
	curthread->td_pcb->pcb_flags &= ~(PCB_NPXINITDONE |
	    PCB_NPXUSERINITDONE);
	critical_exit();
}

int
fill_dbregs(struct thread *td, struct dbreg *dbregs)
{
	struct pcb *pcb;

	if (td == NULL) {
		dbregs->dr[0] = rdr0();
		dbregs->dr[1] = rdr1();
		dbregs->dr[2] = rdr2();
		dbregs->dr[3] = rdr3();
		dbregs->dr[6] = rdr6();
		dbregs->dr[7] = rdr7();
	} else {
		pcb = td->td_pcb;
		dbregs->dr[0] = pcb->pcb_dr0;
		dbregs->dr[1] = pcb->pcb_dr1;
		dbregs->dr[2] = pcb->pcb_dr2;
		dbregs->dr[3] = pcb->pcb_dr3;
		dbregs->dr[6] = pcb->pcb_dr6;
		dbregs->dr[7] = pcb->pcb_dr7;
	}
	dbregs->dr[4] = 0;
	dbregs->dr[5] = 0;
	return (0);
}

int
set_dbregs(struct thread *td, struct dbreg *dbregs)
{
	struct pcb *pcb;
	int i;

	if (td == NULL) {
		load_dr0(dbregs->dr[0]);
		load_dr1(dbregs->dr[1]);
		load_dr2(dbregs->dr[2]);
		load_dr3(dbregs->dr[3]);
		load_dr6(dbregs->dr[6]);
		load_dr7(dbregs->dr[7]);
	} else {
		/*
		 * Don't let an illegal value for dr7 get set.	Specifically,
		 * check for undefined settings.  Setting these bit patterns
		 * result in undefined behaviour and can lead to an unexpected
		 * TRCTRAP.
		 */
		for (i = 0; i < 4; i++) {
			if (DBREG_DR7_ACCESS(dbregs->dr[7], i) == 0x02)
				return (EINVAL);
			if (DBREG_DR7_LEN(dbregs->dr[7], i) == 0x02)
				return (EINVAL);
		}

		pcb = td->td_pcb;

		/*
		 * Don't let a process set a breakpoint that is not within the
		 * process's address space.  If a process could do this, it
		 * could halt the system by setting a breakpoint in the kernel
		 * (if ddb was enabled).  Thus, we need to check to make sure
		 * that no breakpoints are being enabled for addresses outside
		 * process's address space.
		 *
		 * XXX - what about when the watched area of the user's
		 * address space is written into from within the kernel
		 * ... wouldn't that still cause a breakpoint to be generated
		 * from within kernel mode?
		 */

		if (DBREG_DR7_ENABLED(dbregs->dr[7], 0)) {
			/* dr0 is enabled */
			if (dbregs->dr[0] >= VM_MAXUSER_ADDRESS)
				return (EINVAL);
		}

		if (DBREG_DR7_ENABLED(dbregs->dr[7], 1)) {
			/* dr1 is enabled */
			if (dbregs->dr[1] >= VM_MAXUSER_ADDRESS)
				return (EINVAL);
		}

		if (DBREG_DR7_ENABLED(dbregs->dr[7], 2)) {
			/* dr2 is enabled */
			if (dbregs->dr[2] >= VM_MAXUSER_ADDRESS)
				return (EINVAL);
		}

		if (DBREG_DR7_ENABLED(dbregs->dr[7], 3)) {
			/* dr3 is enabled */
			if (dbregs->dr[3] >= VM_MAXUSER_ADDRESS)
				return (EINVAL);
		}

		pcb->pcb_dr0 = dbregs->dr[0];
		pcb->pcb_dr1 = dbregs->dr[1];
		pcb->pcb_dr2 = dbregs->dr[2];
		pcb->pcb_dr3 = dbregs->dr[3];
		pcb->pcb_dr6 = dbregs->dr[6];
		pcb->pcb_dr7 = dbregs->dr[7];

		pcb->pcb_flags |= PCB_DBREGS;
	}

	return (0);
}

/*
 * Return > 0 if a hardware breakpoint has been hit, and the
 * breakpoint was in user space.  Return 0, otherwise.
 */
int
user_dbreg_trap(register_t dr6)
{
        u_int32_t dr7;
        u_int32_t bp;       /* breakpoint bits extracted from dr6 */
        int nbp;            /* number of breakpoints that triggered */
        caddr_t addr[4];    /* breakpoint addresses */
        int i;

        bp = dr6 & DBREG_DR6_BMASK;
        if (bp == 0) {
                /*
                 * None of the breakpoint bits are set meaning this
                 * trap was not caused by any of the debug registers
                 */
                return 0;
        }

        dr7 = rdr7();
        if ((dr7 & 0x000000ff) == 0) {
                /*
                 * all GE and LE bits in the dr7 register are zero,
                 * thus the trap couldn't have been caused by the
                 * hardware debug registers
                 */
                return 0;
        }

        nbp = 0;

        /*
         * at least one of the breakpoints were hit, check to see
         * which ones and if any of them are user space addresses
         */

        if (bp & 0x01) {
                addr[nbp++] = (caddr_t)rdr0();
        }
        if (bp & 0x02) {
                addr[nbp++] = (caddr_t)rdr1();
        }
        if (bp & 0x04) {
                addr[nbp++] = (caddr_t)rdr2();
        }
        if (bp & 0x08) {
                addr[nbp++] = (caddr_t)rdr3();
        }

        for (i = 0; i < nbp; i++) {
                if (addr[i] < (caddr_t)VM_MAXUSER_ADDRESS) {
                        /*
                         * addr[i] is in user space
                         */
                        return nbp;
                }
        }

        /*
         * None of the breakpoints are in user space.
         */
        return 0;
}

#ifdef KDB

/*
 * Provide inb() and outb() as functions.  They are normally only available as
 * inline functions, thus cannot be called from the debugger.
 */

/* silence compiler warnings */
u_char inb_(u_short);
void outb_(u_short, u_char);

u_char
inb_(u_short port)
{
	return inb(port);
}

void
outb_(u_short port, u_char data)
{
	outb(port, data);
}

#endif /* KDB */