More multi-threaded support for virtualization. Move the save context

[dragonfly.git] / sys / platform / pc32 / i386 / machdep.c

/*-
 * 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.
 *
 * 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
 * $FreeBSD: src/sys/i386/i386/machdep.c,v 1.385.2.30 2003/05/31 08:48:05 alc Exp $
 * $DragonFly: src/sys/platform/pc32/i386/machdep.c,v 1.125 2007/07/01 01:11:38 dillon Exp $
 */

#include "use_apm.h"
#include "use_ether.h"
#include "use_npx.h"
#include "use_isa.h"
#include "opt_atalk.h"
#include "opt_compat.h"
#include "opt_cpu.h"
#include "opt_ddb.h"
#include "opt_directio.h"
#include "opt_inet.h"
#include "opt_ipx.h"
#include "opt_maxmem.h"
#include "opt_msgbuf.h"
#include "opt_perfmon.h"
#include "opt_swap.h"
#include "opt_userconfig.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/sysproto.h>
#include <sys/signalvar.h>
#include <sys/kernel.h>
#include <sys/linker.h>
#include <sys/malloc.h>
#include <sys/proc.h>
#include <sys/buf.h>
#include <sys/reboot.h>
#include <sys/mbuf.h>
#include <sys/msgbuf.h>
#include <sys/sysent.h>
#include <sys/sysctl.h>
#include <sys/vmmeter.h>
#include <sys/bus.h>
#include <sys/upcall.h>
#include <sys/usched.h>
#include <sys/reg.h>

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

#include <sys/thread2.h>

#include <sys/user.h>
#include <sys/exec.h>
#include <sys/cons.h>

#include <ddb/ddb.h>

#include <machine/cpu.h>
#include <machine/clock.h>
#include <machine/specialreg.h>
#include <machine/bootinfo.h>
#include <machine/md_var.h>
#include <machine/pcb_ext.h>            /* pcb.h included via sys/user.h */
#include <machine/globaldata.h>         /* CPU_prvspace */
#include <machine/smp.h>
#ifdef PERFMON
#include <machine/perfmon.h>
#endif
#include <machine/cputypes.h>

#ifdef OLD_BUS_ARCH
#include <bus/isa/i386/isa_device.h>
#endif
#include <machine_base/isa/intr_machdep.h>
#include <bus/isa/rtc.h>
#include <machine/vm86.h>
#include <sys/random.h>
#include <sys/ptrace.h>
#include <machine/sigframe.h>

#define PHYSMAP_ENTRIES         10

extern void init386 (int first);
extern void dblfault_handler (void);

extern void printcpuinfo(void); /* XXX header file */
extern void finishidentcpu(void);
extern void panicifcpuunsupported(void);
extern void initializecpu(void);

static void cpu_startup (void *);
#ifndef CPU_DISABLE_SSE
static void set_fpregs_xmm (struct save87 *, struct savexmm *);
static void fill_fpregs_xmm (struct savexmm *, struct save87 *);
#endif /* CPU_DISABLE_SSE */
#ifdef DIRECTIO
extern void ffs_rawread_setup(void);
#endif /* DIRECTIO */
static void init_locks(void);

SYSINIT(cpu, SI_BOOT2_SMP, SI_ORDER_FIRST, cpu_startup, NULL)

int     _udatasel, _ucodesel;
u_int   atdevbase;
#ifdef SMP
int64_t tsc_offsets[MAXCPU];
#else
int64_t tsc_offsets[1];
#endif

#if defined(SWTCH_OPTIM_STATS)
extern int swtch_optim_stats;
SYSCTL_INT(_debug, OID_AUTO, swtch_optim_stats,
        CTLFLAG_RD, &swtch_optim_stats, 0, "");
SYSCTL_INT(_debug, OID_AUTO, tlb_flush_count,
        CTLFLAG_RD, &tlb_flush_count, 0, "");
#endif

int physmem = 0;

static int
sysctl_hw_physmem(SYSCTL_HANDLER_ARGS)
{
        int error = sysctl_handle_int(oidp, 0, ctob(physmem), req);
        return (error);
}

SYSCTL_PROC(_hw, HW_PHYSMEM, physmem, CTLTYPE_INT|CTLFLAG_RD,
        0, 0, sysctl_hw_physmem, "IU", "");

static int
sysctl_hw_usermem(SYSCTL_HANDLER_ARGS)
{
        int error = sysctl_handle_int(oidp, 0,
                ctob(physmem - vmstats.v_wire_count), req);
        return (error);
}

SYSCTL_PROC(_hw, HW_USERMEM, usermem, CTLTYPE_INT|CTLFLAG_RD,
        0, 0, sysctl_hw_usermem, "IU", "");

static int
sysctl_hw_availpages(SYSCTL_HANDLER_ARGS)
{
        int error = sysctl_handle_int(oidp, 0,
                i386_btop(avail_end - avail_start), req);
        return (error);
}

SYSCTL_PROC(_hw, OID_AUTO, availpages, CTLTYPE_INT|CTLFLAG_RD,
        0, 0, sysctl_hw_availpages, "I", "");

static int
sysctl_machdep_msgbuf(SYSCTL_HANDLER_ARGS)
{
        int error;

        /* Unwind the buffer, so that it's linear (possibly starting with
         * some initial nulls).
         */
        error=sysctl_handle_opaque(oidp,msgbufp->msg_ptr+msgbufp->msg_bufr,
                msgbufp->msg_size-msgbufp->msg_bufr,req);
        if(error) return(error);
        if(msgbufp->msg_bufr>0) {
                error=sysctl_handle_opaque(oidp,msgbufp->msg_ptr,
                        msgbufp->msg_bufr,req);
        }
        return(error);
}

SYSCTL_PROC(_machdep, OID_AUTO, msgbuf, CTLTYPE_STRING|CTLFLAG_RD,
        0, 0, sysctl_machdep_msgbuf, "A","Contents of kernel message buffer");

static int msgbuf_clear;

static int
sysctl_machdep_msgbuf_clear(SYSCTL_HANDLER_ARGS)
{
        int error;
        error = sysctl_handle_int(oidp, oidp->oid_arg1, oidp->oid_arg2,
                req);
        if (!error && req->newptr) {
                /* Clear the buffer and reset write pointer */
                bzero(msgbufp->msg_ptr,msgbufp->msg_size);
                msgbufp->msg_bufr=msgbufp->msg_bufx=0;
                msgbuf_clear=0;
        }
        return (error);
}

SYSCTL_PROC(_machdep, OID_AUTO, msgbuf_clear, CTLTYPE_INT|CTLFLAG_RW,
        &msgbuf_clear, 0, sysctl_machdep_msgbuf_clear, "I",
        "Clear kernel message buffer");

vm_paddr_t Maxmem = 0;

vm_paddr_t phys_avail[PHYSMAP_ENTRIES*2+2];

static vm_offset_t buffer_sva, buffer_eva;
vm_offset_t clean_sva, clean_eva;
static vm_offset_t pager_sva, pager_eva;
static struct trapframe proc0_tf;

static void
cpu_startup(void *dummy)
{
        caddr_t v;
        vm_size_t size = 0;
        vm_offset_t firstaddr;

        if (boothowto & RB_VERBOSE)
                bootverbose++;

        /*
         * Good {morning,afternoon,evening,night}.
         */
        kprintf("%s", version);
        startrtclock();
        printcpuinfo();
        panicifcpuunsupported();
#ifdef PERFMON
        perfmon_init();
#endif
        kprintf("real memory  = %llu (%lluK bytes)\n", ptoa(Maxmem), ptoa(Maxmem) / 1024);
        /*
         * Display any holes after the first chunk of extended memory.
         */
        if (bootverbose) {
                int indx;

                kprintf("Physical memory chunk(s):\n");
                for (indx = 0; phys_avail[indx + 1] != 0; indx += 2) {
                        vm_paddr_t size1 = phys_avail[indx + 1] - phys_avail[indx];

                        kprintf("0x%08llx - 0x%08llx, %llu bytes (%llu pages)\n",
                            phys_avail[indx], phys_avail[indx + 1] - 1, size1,
                            size1 / PAGE_SIZE);
                }
        }

        /*
         * Allocate space for system data structures.
         * The first available kernel virtual address is in "v".
         * As pages of kernel virtual memory are allocated, "v" is incremented.
         * As pages of memory are allocated and cleared,
         * "firstaddr" is incremented.
         * An index into the kernel page table corresponding to the
         * virtual memory address maintained in "v" is kept in "mapaddr".
         */

        /*
         * Make two passes.  The first pass calculates how much memory is
         * needed and allocates it.  The second pass assigns virtual
         * addresses to the various data structures.
         */
        firstaddr = 0;
again:
        v = (caddr_t)firstaddr;

#define valloc(name, type, num) \
            (name) = (type *)v; v = (caddr_t)((name)+(num))
#define valloclim(name, type, num, lim) \
            (name) = (type *)v; v = (caddr_t)((lim) = ((name)+(num)))

        /*
         * The nominal buffer size (and minimum KVA allocation) is BKVASIZE.
         * For the first 64MB of ram nominally allocate sufficient buffers to
         * cover 1/4 of our ram.  Beyond the first 64MB allocate additional
         * buffers to cover 1/20 of our ram over 64MB.  When auto-sizing
         * the buffer cache we limit the eventual kva reservation to
         * maxbcache bytes.
         *
         * factor represents the 1/4 x ram conversion.
         */
        if (nbuf == 0) {
                int factor = 4 * BKVASIZE / 1024;
                int kbytes = physmem * (PAGE_SIZE / 1024);

                nbuf = 50;
                if (kbytes > 4096)
                        nbuf += min((kbytes - 4096) / factor, 65536 / factor);
                if (kbytes > 65536)
                        nbuf += (kbytes - 65536) * 2 / (factor * 5);
                if (maxbcache && nbuf > maxbcache / BKVASIZE)
                        nbuf = maxbcache / BKVASIZE;
        }

        /*
         * Do not allow the buffer_map to be more then 1/2 the size of the
         * kernel_map.
         */
        if (nbuf > (virtual_end - virtual_start) / (BKVASIZE * 2)) {
                nbuf = (virtual_end - virtual_start) / (BKVASIZE * 2);
                kprintf("Warning: nbufs capped at %d\n", nbuf);
        }

        nswbuf = max(min(nbuf/4, 256), 16);
#ifdef NSWBUF_MIN
        if (nswbuf < NSWBUF_MIN)
                nswbuf = NSWBUF_MIN;
#endif
#ifdef DIRECTIO
        ffs_rawread_setup();
#endif

        valloc(swbuf, struct buf, nswbuf);
        valloc(buf, struct buf, nbuf);

        /*
         * End of first pass, size has been calculated so allocate memory
         */
        if (firstaddr == 0) {
                size = (vm_size_t)(v - firstaddr);
                firstaddr = kmem_alloc(&kernel_map, round_page(size));
                if (firstaddr == 0)
                        panic("startup: no room for tables");
                goto again;
        }

        /*
         * End of second pass, addresses have been assigned
         */
        if ((vm_size_t)(v - firstaddr) != size)
                panic("startup: table size inconsistency");

        kmem_suballoc(&kernel_map, &clean_map, &clean_sva, &clean_eva,
                      (nbuf*BKVASIZE) + (nswbuf*MAXPHYS) + pager_map_size);
        kmem_suballoc(&clean_map, &buffer_map, &buffer_sva, &buffer_eva,
                      (nbuf*BKVASIZE));
        buffer_map.system_map = 1;
        kmem_suballoc(&clean_map, &pager_map, &pager_sva, &pager_eva,
                      (nswbuf*MAXPHYS) + pager_map_size);
        pager_map.system_map = 1;

#if defined(USERCONFIG)
        userconfig();
        cninit();               /* the preferred console may have changed */
#endif

        kprintf("avail memory = %u (%uK bytes)\n", ptoa(vmstats.v_free_count),
            ptoa(vmstats.v_free_count) / 1024);

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

#ifdef SMP
        /*
         * OK, enough kmem_alloc/malloc state should be up, lets get on with it!
         */
        mp_start();                     /* fire up the APs and APICs */
        mp_announce();
#endif  /* SMP */
        cpu_setregs();
}

/*
 * Send an interrupt to process.
 *
 * Stack is set up to allow sigcode stored
 * at top to call routine, followed by kcall
 * to sigreturn routine below.  After sigreturn
 * resets the signal mask, the stack, and the
 * frame pointer, it returns to the user
 * specified pc, psl.
 */
void
sendsig(sig_t catcher, int sig, sigset_t *mask, u_long code)
{
        struct lwp *lp = curthread->td_lwp;
        struct proc *p = lp->lwp_proc;
        struct trapframe *regs;
        struct sigacts *psp = p->p_sigacts;
        struct sigframe sf, *sfp;
        int oonstack;

        regs = lp->lwp_md.md_regs;
        oonstack = (lp->lwp_sigstk.ss_flags & SS_ONSTACK) ? 1 : 0;

        /* save user context */
        bzero(&sf, sizeof(struct sigframe));
        sf.sf_uc.uc_sigmask = *mask;
        sf.sf_uc.uc_stack = lp->lwp_sigstk;
        sf.sf_uc.uc_mcontext.mc_onstack = oonstack;
        bcopy(regs, &sf.sf_uc.uc_mcontext.mc_gs, sizeof(struct trapframe));

        /* make the size of the saved context visible to userland */
        sf.sf_uc.uc_mcontext.mc_len = sizeof(sf.sf_uc.uc_mcontext);

        /* save mailbox pending state for syscall interlock semantics */
        if (p->p_flag & P_MAILBOX)
                sf.sf_uc.uc_mcontext.mc_xflags |= PGEX_MAILBOX;

        /* Allocate and validate space for the signal handler context. */
        if ((lp->lwp_flag & LWP_ALTSTACK) != 0 && !oonstack &&
            SIGISMEMBER(psp->ps_sigonstack, sig)) {
                sfp = (struct sigframe *)(lp->lwp_sigstk.ss_sp +
                    lp->lwp_sigstk.ss_size - sizeof(struct sigframe));
                lp->lwp_sigstk.ss_flags |= SS_ONSTACK;
        } else {
                sfp = (struct sigframe *)regs->tf_esp - 1;
        }

        /* Translate the signal is appropriate */
        if (p->p_sysent->sv_sigtbl) {
                if (sig <= p->p_sysent->sv_sigsize)
                        sig = p->p_sysent->sv_sigtbl[_SIG_IDX(sig)];
        }

        /* Build the argument list for the signal handler. */
        sf.sf_signum = sig;
        sf.sf_ucontext = (register_t)&sfp->sf_uc;
        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 siginfo structure */
                sf.sf_si.si_signo = sig;
                sf.sf_si.si_code = code;
                sf.sf_si.si_addr = (void*)regs->tf_err;
        }
        else {
                /* Old FreeBSD-style arguments. */
                sf.sf_siginfo = code;
                sf.sf_addr = regs->tf_err;
                sf.sf_ahu.sf_handler = catcher;
        }

        /*
         * 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 = &lp->lwp_thread->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(struct sigframe)) != 0) {
                /*
                 * Something is wrong with the stack pointer.
                 * ...Kill the process.
                 */
                sigexit(p, SIGILL);
        }

        regs->tf_esp = (int)sfp;
        regs->tf_eip = PS_STRINGS - *(p->p_sysent->sv_szsigcode);
        regs->tf_eflags &= ~PSL_T;
        regs->tf_cs = _ucodesel;
        regs->tf_ds = _udatasel;
        regs->tf_es = _udatasel;

        /*
         * Allow the signal handler to inherit %fs in addition to %gs as
         * the userland program might be using both.
         *
         * However, if a T_PROTFLT occured the segment registers could be
         * totally broken.  They must be reset in order to be able to
         * return to userland.
         */
        if (regs->tf_trapno == T_PROTFLT) {
                regs->tf_fs = _udatasel;
                regs->tf_gs = _udatasel;
        }
        regs->tf_ss = _udatasel;
}

/*
 * Sanitize the trapframe for a virtual kernel passing control to a custom
 * VM context.  Remove any items that would otherwise create a privilage
 * issue.
 *
 * XXX at the moment we allow userland to set the resume flag.  Is this a
 * bad idea?
 */
int
cpu_sanitize_frame(struct trapframe *frame)
{
        frame->tf_cs = _ucodesel;
        frame->tf_ds = _udatasel;
        frame->tf_es = _udatasel;       /* XXX allow userland this one too? */
#if 0
        frame->tf_fs = _udatasel;
        frame->tf_gs = _udatasel;
#endif
        frame->tf_ss = _udatasel;
        frame->tf_eflags &= (PSL_RF | PSL_USERCHANGE);
        frame->tf_eflags |= PSL_RESERVED_DEFAULT | PSL_I;
        return(0);
}

int
cpu_sanitize_tls(struct savetls *tls)
{
         struct segment_descriptor *desc;
         int i;

         for (i = 0; i < NGTLS; ++i) {
                desc = &tls->tls[i];
                if (desc->sd_dpl == 0 && desc->sd_type == 0)
                        continue;
                if (desc->sd_def32 == 0)
                        return(ENXIO);
                if (desc->sd_type != SDT_MEMRWA)
                        return(ENXIO);
                if (desc->sd_dpl != SEL_UPL)
                        return(ENXIO);
                if (desc->sd_xx != 0 || desc->sd_p != 1)
                        return(ENXIO);
         }
         return(0);
}

/*
 * sigreturn(ucontext_t *sigcntxp)
 *
 * 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.
 */
#define EFL_SECURE(ef, oef)     ((((ef) ^ (oef)) & ~PSL_USERCHANGE) == 0)
#define CS_SECURE(cs)           (ISPL(cs) == SEL_UPL)

int
sys_sigreturn(struct sigreturn_args *uap)
{
        struct lwp *lp = curthread->td_lwp;
        struct proc *p = lp->lwp_proc;
        struct trapframe *regs;
        ucontext_t *ucp;
        int cs, eflags;

        ucp = uap->sigcntxp;

        if (!useracc((caddr_t)ucp, sizeof(ucontext_t), VM_PROT_READ))
                return (EFAULT);

        regs = lp->lwp_md.md_regs;
        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 (lp->lwp_thread->td_pcb->pcb_ext == 0)
                        return (EINVAL);
                vm86 = &lp->lwp_thread->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))
                        trapsignal(lp, SIGBUS, 0);

                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_gs, 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 = tf->tf_gs;
                tf->tf_ds = _udatasel;
                tf->tf_es = _udatasel;
#if 0
                tf->tf_fs = _udatasel;
                tf->tf_gs = _udatasel;
#endif
        } else {
                /*
                 * Don't allow users to change privileged or reserved flags.
                 */
                /*
                 * XXX do allow users to change the privileged flag PSL_RF.
                 * The cpu sets PSL_RF in tf_eflags for faults.  Debuggers
                 * should sometimes set it there too.  tf_eflags is kept in
                 * the signal context during signal handling and there is no
                 * other place to remember it, so the PSL_RF bit may be
                 * corrupted by the signal handler without us knowing.
                 * Corruption of the PSL_RF bit at worst causes one more or
                 * one less debugger trap, so allowing it is fairly harmless.
                 */
                if (!EFL_SECURE(eflags & ~PSL_RF, regs->tf_eflags & ~PSL_RF)) {
                        kprintf("sigreturn: eflags = 0x%x\n", 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)) {
                        kprintf("sigreturn: cs = 0x%x\n", cs);
                        trapsignal(lp, SIGBUS, T_PROTFLT);
                        return(EINVAL);
                }
                bcopy(&ucp->uc_mcontext.mc_gs, regs, sizeof(struct trapframe));
        }

        /*
         * Merge saved signal mailbox pending flag to maintain interlock
         * semantics against system calls.
         */
        if (ucp->uc_mcontext.mc_xflags & PGEX_MAILBOX)
                p->p_flag |= P_MAILBOX;

        if (ucp->uc_mcontext.mc_onstack & 1)
                lp->lwp_sigstk.ss_flags |= SS_ONSTACK;
        else
                lp->lwp_sigstk.ss_flags &= ~SS_ONSTACK;

        lp->lwp_sigmask = ucp->uc_sigmask;
        SIG_CANTMASK(lp->lwp_sigmask);
        return(EJUSTRETURN);
}

/*
 * Stack frame on entry to function.  %eax will contain the function vector,
 * %ecx will contain the function data.  flags, ecx, and eax will have 
 * already been pushed on the stack.
 */
struct upc_frame {
        register_t      eax;
        register_t      ecx;
        register_t      edx;
        register_t      flags;
        register_t      oldip;
};

void
sendupcall(struct vmupcall *vu, int morepending)
{
        struct lwp *lp = curthread->td_lwp;
        struct trapframe *regs;
        struct upcall upcall;
        struct upc_frame upc_frame;
        int     crit_count = 0;

        /*
         * If we are a virtual kernel running an emulated user process
         * context, switch back to the virtual kernel context before
         * trying to post the signal.
         */
        if (lp->lwp_vkernel && lp->lwp_vkernel->ve) {
                lp->lwp_md.md_regs->tf_trapno = 0;
                vkernel_trap(lp, lp->lwp_md.md_regs);
        }

        /*
         * Get the upcall data structure
         */
        if (copyin(lp->lwp_upcall, &upcall, sizeof(upcall)) ||
            copyin((char *)upcall.upc_uthread + upcall.upc_critoff, &crit_count, sizeof(int))
        ) {
                vu->vu_pending = 0;
                kprintf("bad upcall address\n");
                return;
        }

        /*
         * If the data structure is already marked pending or has a critical
         * section count, mark the data structure as pending and return 
         * without doing an upcall.  vu_pending is left set.
         */
        if (upcall.upc_pending || crit_count >= vu->vu_pending) {
                if (upcall.upc_pending < vu->vu_pending) {
                        upcall.upc_pending = vu->vu_pending;
                        copyout(&upcall.upc_pending, &lp->lwp_upcall->upc_pending,
                                sizeof(upcall.upc_pending));
                }
                return;
        }

        /*
         * We can run this upcall now, clear vu_pending.
         *
         * Bump our critical section count and set or clear the
         * user pending flag depending on whether more upcalls are
         * pending.  The user will be responsible for calling 
         * upc_dispatch(-1) to process remaining upcalls.
         */
        vu->vu_pending = 0;
        upcall.upc_pending = morepending;
        crit_count += TDPRI_CRIT;
        copyout(&upcall.upc_pending, &lp->lwp_upcall->upc_pending, 
                sizeof(upcall.upc_pending));
        copyout(&crit_count, (char *)upcall.upc_uthread + upcall.upc_critoff,
                sizeof(int));

        /*
         * Construct a stack frame and issue the upcall
         */
        regs = lp->lwp_md.md_regs;
        upc_frame.eax = regs->tf_eax;
        upc_frame.ecx = regs->tf_ecx;
        upc_frame.edx = regs->tf_edx;
        upc_frame.flags = regs->tf_eflags;
        upc_frame.oldip = regs->tf_eip;
        if (copyout(&upc_frame, (void *)(regs->tf_esp - sizeof(upc_frame)),
            sizeof(upc_frame)) != 0) {
                kprintf("bad stack on upcall\n");
        } else {
                regs->tf_eax = (register_t)vu->vu_func;
                regs->tf_ecx = (register_t)vu->vu_data;
                regs->tf_edx = (register_t)lp->lwp_upcall;
                regs->tf_eip = (register_t)vu->vu_ctx;
                regs->tf_esp -= sizeof(upc_frame);
        }
}

/*
 * fetchupcall occurs in the context of a system call, which means that
 * we have to return EJUSTRETURN in order to prevent eax and edx from
 * being overwritten by the syscall return value.
 *
 * if vu is not NULL we return the new context in %edx, the new data in %ecx,
 * and the function pointer in %eax.  
 */
int
fetchupcall (struct vmupcall *vu, int morepending, void *rsp)
{
        struct upc_frame upc_frame;
        struct lwp *lp = curthread->td_lwp;
        struct trapframe *regs;
        int error;
        struct upcall upcall;
        int crit_count;

        regs = lp->lwp_md.md_regs;

        error = copyout(&morepending, &lp->lwp_upcall->upc_pending, sizeof(int));
        if (error == 0) {
            if (vu) {
                /*
                 * This jumps us to the next ready context.
                 */
                vu->vu_pending = 0;
                error = copyin(lp->lwp_upcall, &upcall, sizeof(upcall));
                crit_count = 0;
                if (error == 0)
                        error = copyin((char *)upcall.upc_uthread + upcall.upc_critoff, &crit_count, sizeof(int));
                crit_count += TDPRI_CRIT;
                if (error == 0)
                        error = copyout(&crit_count, (char *)upcall.upc_uthread + upcall.upc_critoff, sizeof(int));
                regs->tf_eax = (register_t)vu->vu_func;
                regs->tf_ecx = (register_t)vu->vu_data;
                regs->tf_edx = (register_t)lp->lwp_upcall;
                regs->tf_eip = (register_t)vu->vu_ctx;
                regs->tf_esp = (register_t)rsp;
            } else {
                /*
                 * This returns us to the originally interrupted code.
                 */
                error = copyin(rsp, &upc_frame, sizeof(upc_frame));
                regs->tf_eax = upc_frame.eax;
                regs->tf_ecx = upc_frame.ecx;
                regs->tf_edx = upc_frame.edx;
                regs->tf_eflags = (regs->tf_eflags & ~PSL_USERCHANGE) |
                                (upc_frame.flags & PSL_USERCHANGE);
                regs->tf_eip = upc_frame.oldip;
                regs->tf_esp = (register_t)((char *)rsp + sizeof(upc_frame));
            }
        }
        if (error == 0)
                error = EJUSTRETURN;
        return(error);
}

/*
 * Machine dependent boot() routine
 *
 * I haven't seen anything to put here yet
 * Possibly some stuff might be grafted back here from boot()
 */
void
cpu_boot(int howto)
{
}

/*
 * Shutdown the CPU as much as possible
 */
void
cpu_halt(void)
{
        for (;;)
                __asm__ __volatile("hlt");
}

/*
 * cpu_idle() represents the idle LWKT.  You cannot return from this function
 * (unless you want to blow things up!).  Instead we look for runnable threads
 * and loop or halt as appropriate.  Giant is not held on entry to the thread.
 *
 * The main loop is entered with a critical section held, we must release
 * the critical section before doing anything else.  lwkt_switch() will
 * check for pending interrupts due to entering and exiting its own 
 * critical section.
 *
 * Note on cpu_idle_hlt:  On an SMP system we rely on a scheduler IPI
 * to wake a HLTed cpu up.  However, there are cases where the idlethread
 * will be entered with the possibility that no IPI will occur and in such
 * cases lwkt_switch() sets TDF_IDLE_NOHLT.
 */
static int      cpu_idle_hlt = 1;
static int      cpu_idle_hltcnt;
static int      cpu_idle_spincnt;
SYSCTL_INT(_machdep, OID_AUTO, cpu_idle_hlt, CTLFLAG_RW,
    &cpu_idle_hlt, 0, "Idle loop HLT enable");
SYSCTL_INT(_machdep, OID_AUTO, cpu_idle_hltcnt, CTLFLAG_RW,
    &cpu_idle_hltcnt, 0, "Idle loop entry halts");
SYSCTL_INT(_machdep, OID_AUTO, cpu_idle_spincnt, CTLFLAG_RW,
    &cpu_idle_spincnt, 0, "Idle loop entry spins");

static void
cpu_idle_default_hook(void)
{
        /*
         * We must guarentee that hlt is exactly the instruction
         * following the sti.
         */
        __asm __volatile("sti; hlt");
}

/* Other subsystems (e.g., ACPI) can hook this later. */
void (*cpu_idle_hook)(void) = cpu_idle_default_hook;

void
cpu_idle(void)
{
        struct thread *td = curthread;

        crit_exit();
        KKASSERT(td->td_pri < TDPRI_CRIT);
        for (;;) {
                /*
                 * See if there are any LWKTs ready to go.
                 */
                lwkt_switch();

                /*
                 * If we are going to halt call splz unconditionally after
                 * CLIing to catch any interrupt races.  Note that we are
                 * at SPL0 and interrupts are enabled.
                 */
                if (cpu_idle_hlt && !lwkt_runnable() &&
                    (td->td_flags & TDF_IDLE_NOHLT) == 0) {
                        __asm __volatile("cli");
                        splz();
                        if (!lwkt_runnable())
                            cpu_idle_hook();
#ifdef SMP
                        else
                            __asm __volatile("pause");
#endif
                        ++cpu_idle_hltcnt;
                } else {
                        td->td_flags &= ~TDF_IDLE_NOHLT;
                        splz();
#ifdef SMP
                        __asm __volatile("sti; pause");
#else
                        __asm __volatile("sti");
#endif
                        ++cpu_idle_spincnt;
                }
        }
}

/*
 * Clear registers on exec
 */
void
exec_setregs(u_long entry, u_long stack, u_long ps_strings)
{
        struct thread *td = curthread;
        struct lwp *lp = td->td_lwp;
        struct pcb *pcb = td->td_pcb;
        struct trapframe *regs = lp->lwp_md.md_regs;

        /* was i386_user_cleanup() in NetBSD */
        user_ldt_free(pcb);
  
        bzero((char *)regs, sizeof(struct trapframe));
        regs->tf_eip = entry;
        regs->tf_esp = stack;
        regs->tf_eflags = PSL_USER | (regs->tf_eflags & PSL_T);
        regs->tf_ss = _udatasel;
        regs->tf_ds = _udatasel;
        regs->tf_es = _udatasel;
        regs->tf_fs = _udatasel;
        regs->tf_gs = _udatasel;
        regs->tf_cs = _ucodesel;

        /* PS_STRINGS value for BSD/OS binaries.  It is 0 for non-BSD/OS. */
        regs->tf_ebx = 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 == td->td_pcb) {
                        /*
                         * 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;
        }

        /*
         * Initialize the math emulator (if any) for the current process.
         * Actually, just clear the bit that says that the emulator has
         * been initialized.  Initialization is delayed until the process
         * traps to the emulator (if it is done at all) mainly because
         * emulators don't provide an entry point for initialization.
         */
        pcb->pcb_flags &= ~FP_SOFTFP;

        /*
         * note: do not set CR0_TS here.  npxinit() must do it after clearing
         * gd_npxthread.  Otherwise a preemptive interrupt thread may panic
         * in npxdna().
         */
        crit_enter();
        load_cr0(rcr0() | CR0_MP);

#if NNPX > 0
        /* Initialize the npx (if any) for the current process. */
        npxinit(__INITIAL_NPXCW__);
#endif
        crit_exit();

        /*
         * note: linux emulator needs edx to be 0x0 on entry, which is
         * handled in execve simply by setting the 64 bit syscall
         * return value to 0.
         */
}

void
cpu_setregs(void)
{
        unsigned int cr0;

        cr0 = rcr0();
        cr0 |= CR0_NE;                  /* Done by npxinit() */
        cr0 |= CR0_MP | CR0_TS;         /* Done at every execve() too. */
#ifdef I386_CPU
        if (cpu_class != CPUCLASS_386)
#endif
                cr0 |= CR0_WP | CR0_AM;
        load_cr0(cr0);
        load_gs(_udatasel);
}

static int
sysctl_machdep_adjkerntz(SYSCTL_HANDLER_ARGS)
{
        int error;
        error = sysctl_handle_int(oidp, oidp->oid_arg1, oidp->oid_arg2,
                req);
        if (!error && req->newptr)
                resettodr();
        return (error);
}

SYSCTL_PROC(_machdep, CPU_ADJKERNTZ, adjkerntz, CTLTYPE_INT|CTLFLAG_RW,
        &adjkerntz, 0, sysctl_machdep_adjkerntz, "I", "");

SYSCTL_INT(_machdep, CPU_DISRTCSET, disable_rtc_set,
        CTLFLAG_RW, &disable_rtc_set, 0, "");

SYSCTL_STRUCT(_machdep, CPU_BOOTINFO, bootinfo, 
        CTLFLAG_RD, &bootinfo, bootinfo, "");

SYSCTL_INT(_machdep, CPU_WALLCLOCK, wall_cmos_clock,
        CTLFLAG_RW, &wall_cmos_clock, 0, "");

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

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

/*
 * Initialize segments & interrupt table
 */

int _default_ldt;
union descriptor gdt[NGDT * MAXCPU];    /* global descriptor table */
static struct gate_descriptor idt0[NIDT];
struct gate_descriptor *idt = &idt0[0]; /* interrupt descriptor table */
union descriptor ldt[NLDT];             /* local descriptor table */

/* table descriptors - used to load tables by cpu */
struct region_descriptor r_gdt, r_idt;

#if defined(I586_CPU) && !defined(NO_F00F_HACK)
extern int has_f00f_bug;
#endif

static struct i386tss dblfault_tss;
static char dblfault_stack[PAGE_SIZE];

extern  struct user *proc0paddr;


/* software prototypes -- in more palatable form */
struct soft_segment_descriptor gdt_segs[] = {
/* GNULL_SEL    0 Null Descriptor */
{       0x0,                    /* segment base address  */
        0x0,                    /* length */
        0,                      /* segment type */
        0,                      /* segment descriptor priority level */
        0,                      /* segment descriptor present */
        0, 0,
        0,                      /* default 32 vs 16 bit size */
        0                       /* limit granularity (byte/page units)*/ },
/* GCODE_SEL    1 Code Descriptor for kernel */
{       0x0,                    /* segment base address  */
        0xfffff,                /* length - all address space */
        SDT_MEMERA,             /* segment type */
        0,                      /* segment descriptor priority level */
        1,                      /* segment descriptor present */
        0, 0,
        1,                      /* default 32 vs 16 bit size */
        1                       /* limit granularity (byte/page units)*/ },
/* GDATA_SEL    2 Data Descriptor for kernel */
{       0x0,                    /* segment base address  */
        0xfffff,                /* length - all address space */
        SDT_MEMRWA,             /* segment type */
        0,                      /* segment descriptor priority level */
        1,                      /* segment descriptor present */
        0, 0,
        1,                      /* default 32 vs 16 bit size */
        1                       /* limit granularity (byte/page units)*/ },
/* GPRIV_SEL    3 SMP Per-Processor Private Data Descriptor */
{       0x0,                    /* segment base address  */
        0xfffff,                /* length - all address space */
        SDT_MEMRWA,             /* segment type */
        0,                      /* segment descriptor priority level */
        1,                      /* segment descriptor present */
        0, 0,
        1,                      /* default 32 vs 16 bit size */
        1                       /* limit granularity (byte/page units)*/ },
/* GPROC0_SEL   4 Proc 0 Tss Descriptor */
{
        0x0,                    /* segment base address */
        sizeof(struct i386tss)-1,/* length - all address space */
        SDT_SYS386TSS,          /* segment type */
        0,                      /* segment descriptor priority level */
        1,                      /* segment descriptor present */
        0, 0,
        0,                      /* unused - default 32 vs 16 bit size */
        0                       /* limit granularity (byte/page units)*/ },
/* GLDT_SEL     5 LDT Descriptor */
{       (int) ldt,              /* segment base address  */
        sizeof(ldt)-1,          /* length - all address space */
        SDT_SYSLDT,             /* segment type */
        SEL_UPL,                /* segment descriptor priority level */
        1,                      /* segment descriptor present */
        0, 0,
        0,                      /* unused - default 32 vs 16 bit size */
        0                       /* limit granularity (byte/page units)*/ },
/* GUSERLDT_SEL 6 User LDT Descriptor per process */
{       (int) ldt,              /* segment base address  */
        (512 * sizeof(union descriptor)-1),             /* length */
        SDT_SYSLDT,             /* segment type */
        0,                      /* segment descriptor priority level */
        1,                      /* segment descriptor present */
        0, 0,
        0,                      /* unused - default 32 vs 16 bit size */
        0                       /* limit granularity (byte/page units)*/ },
/* GTGATE_SEL   7 Null Descriptor - Placeholder */
{       0x0,                    /* segment base address  */
        0x0,                    /* length - all address space */
        0,                      /* segment type */
        0,                      /* segment descriptor priority level */
        0,                      /* segment descriptor present */
        0, 0,
        0,                      /* default 32 vs 16 bit size */
        0                       /* limit granularity (byte/page units)*/ },
/* GBIOSLOWMEM_SEL 8 BIOS access to realmode segment 0x40, must be #8 in GDT */
{       0x400,                  /* segment base address */
        0xfffff,                /* length */
        SDT_MEMRWA,             /* segment type */
        0,                      /* segment descriptor priority level */
        1,                      /* segment descriptor present */
        0, 0,
        1,                      /* default 32 vs 16 bit size */
        1                       /* limit granularity (byte/page units)*/ },
/* GPANIC_SEL   9 Panic Tss Descriptor */
{       (int) &dblfault_tss,    /* segment base address  */
        sizeof(struct i386tss)-1,/* length - all address space */
        SDT_SYS386TSS,          /* segment type */
        0,                      /* segment descriptor priority level */
        1,                      /* segment descriptor present */
        0, 0,
        0,                      /* unused - default 32 vs 16 bit size */
        0                       /* limit granularity (byte/page units)*/ },
/* GBIOSCODE32_SEL 10 BIOS 32-bit interface (32bit Code) */
{       0,                      /* segment base address (overwritten)  */
        0xfffff,                /* length */
        SDT_MEMERA,             /* segment type */
        0,                      /* segment descriptor priority level */
        1,                      /* segment descriptor present */
        0, 0,
        0,                      /* default 32 vs 16 bit size */
        1                       /* limit granularity (byte/page units)*/ },
/* GBIOSCODE16_SEL 11 BIOS 32-bit interface (16bit Code) */
{       0,                      /* segment base address (overwritten)  */
        0xfffff,                /* length */
        SDT_MEMERA,             /* segment type */
        0,                      /* segment descriptor priority level */
        1,                      /* segment descriptor present */
        0, 0,
        0,                      /* default 32 vs 16 bit size */
        1                       /* limit granularity (byte/page units)*/ },
/* GBIOSDATA_SEL 12 BIOS 32-bit interface (Data) */
{       0,                      /* segment base address (overwritten) */
        0xfffff,                /* length */
        SDT_MEMRWA,             /* segment type */
        0,                      /* segment descriptor priority level */
        1,                      /* segment descriptor present */
        0, 0,
        1,                      /* default 32 vs 16 bit size */
        1                       /* limit granularity (byte/page units)*/ },
/* GBIOSUTIL_SEL 13 BIOS 16-bit interface (Utility) */
{       0,                      /* segment base address (overwritten) */
        0xfffff,                /* length */
        SDT_MEMRWA,             /* segment type */
        0,                      /* segment descriptor priority level */
        1,                      /* segment descriptor present */
        0, 0,
        0,                      /* default 32 vs 16 bit size */
        1                       /* limit granularity (byte/page units)*/ },
/* GBIOSARGS_SEL 14 BIOS 16-bit interface (Arguments) */
{       0,                      /* segment base address (overwritten) */
        0xfffff,                /* length */
        SDT_MEMRWA,             /* segment type */
        0,                      /* segment descriptor priority level */
        1,                      /* segment descriptor present */
        0, 0,
        0,                      /* default 32 vs 16 bit size */
        1                       /* limit granularity (byte/page units)*/ },
/* GTLS_START 15 TLS */
{       0x0,                    /* segment base address  */
        0x0,                    /* length */
        0,                      /* segment type */
        0,                      /* segment descriptor priority level */
        0,                      /* segment descriptor present */
        0, 0,
        0,                      /* default 32 vs 16 bit size */
        0                       /* limit granularity (byte/page units)*/ },
/* GTLS_START+1 16 TLS */
{       0x0,                    /* segment base address  */
        0x0,                    /* length */
        0,                      /* segment type */
        0,                      /* segment descriptor priority level */
        0,                      /* segment descriptor present */
        0, 0,
        0,                      /* default 32 vs 16 bit size */
        0                       /* limit granularity (byte/page units)*/ },
/* GTLS_END 17 TLS */
{       0x0,                    /* segment base address  */
        0x0,                    /* length */
        0,                      /* segment type */
        0,                      /* segment descriptor priority level */
        0,                      /* segment descriptor present */
        0, 0,
        0,                      /* default 32 vs 16 bit size */
        0                       /* limit granularity (byte/page units)*/ },
};

static struct soft_segment_descriptor ldt_segs[] = {
        /* Null Descriptor - overwritten by call gate */
{       0x0,                    /* segment base address  */
        0x0,                    /* length - all address space */
        0,                      /* segment type */
        0,                      /* segment descriptor priority level */
        0,                      /* segment descriptor present */
        0, 0,
        0,                      /* default 32 vs 16 bit size */
        0                       /* limit granularity (byte/page units)*/ },
        /* Null Descriptor - overwritten by call gate */
{       0x0,                    /* segment base address  */
        0x0,                    /* length - all address space */
        0,                      /* segment type */
        0,                      /* segment descriptor priority level */
        0,                      /* segment descriptor present */
        0, 0,
        0,                      /* default 32 vs 16 bit size */
        0                       /* limit granularity (byte/page units)*/ },
        /* Null Descriptor - overwritten by call gate */
{       0x0,                    /* segment base address  */
        0x0,                    /* length - all address space */
        0,                      /* segment type */
        0,                      /* segment descriptor priority level */
        0,                      /* segment descriptor present */
        0, 0,
        0,                      /* default 32 vs 16 bit size */
        0                       /* limit granularity (byte/page units)*/ },
        /* Code Descriptor for user */
{       0x0,                    /* segment base address  */
        0xfffff,                /* length - all address space */
        SDT_MEMERA,             /* segment type */
        SEL_UPL,                /* segment descriptor priority level */
        1,                      /* segment descriptor present */
        0, 0,
        1,                      /* default 32 vs 16 bit size */
        1                       /* limit granularity (byte/page units)*/ },
        /* Null Descriptor - overwritten by call gate */
{       0x0,                    /* segment base address  */
        0x0,                    /* length - all address space */
        0,                      /* segment type */
        0,                      /* segment descriptor priority level */
        0,                      /* segment descriptor present */
        0, 0,
        0,                      /* default 32 vs 16 bit size */
        0                       /* limit granularity (byte/page units)*/ },
        /* Data Descriptor for user */
{       0x0,                    /* segment base address  */
        0xfffff,                /* length - all address space */
        SDT_MEMRWA,             /* segment type */
        SEL_UPL,                /* segment descriptor priority level */
        1,                      /* segment descriptor present */
        0, 0,
        1,                      /* default 32 vs 16 bit size */
        1                       /* limit granularity (byte/page units)*/ },
};

void
setidt(int idx, inthand_t *func, int typ, int dpl, int selec)
{
        struct gate_descriptor *ip;

        ip = idt + idx;
        ip->gd_looffset = (int)func;
        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 = ((int)func)>>16 ;
}

#define IDTVEC(name)    __CONCAT(X,name)

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(fpu), IDTVEC(align),
        IDTVEC(xmm), IDTVEC(syscall),
        IDTVEC(rsvd0);
extern inthand_t
        IDTVEC(int0x80_syscall);

#ifdef DEBUG_INTERRUPTS
extern inthand_t *Xrsvdary[256];
#endif

void
sdtossd(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;
}

/*
 * 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.
 */
static void
getmemsize(int first)
{
        int i, physmap_idx, pa_indx;
        int hasbrokenint12;
        u_int basemem, extmem;
        struct vm86frame vmf;
        struct vm86context vmc;
        vm_offset_t pa;
        vm_offset_t physmap[PHYSMAP_ENTRIES*2];
        pt_entry_t *pte;
        const char *cp;
        struct {
                u_int64_t base;
                u_int64_t length;
                u_int32_t type;
        } *smap;
        quad_t dcons_addr, dcons_size;

        hasbrokenint12 = 0;
        TUNABLE_INT_FETCH("hw.hasbrokenint12", &hasbrokenint12);
        bzero(&vmf, sizeof(struct vm86frame));
        bzero(physmap, sizeof(physmap));
        basemem = 0;

        /*
         * Some newer BIOSes has broken INT 12H implementation which cause
         * kernel panic immediately. In this case, we need to scan SMAP
         * with INT 15:E820 first, then determine base memory size.
         */
        if (hasbrokenint12) {
                goto int15e820;
        }

        /*
         * Perform "base memory" related probes & setup.  If we get a crazy
         * value give the bios some scribble space just in case.
         */
        vm86_intcall(0x12, &vmf);
        basemem = vmf.vmf_ax;
        if (basemem > 640) {
                kprintf("Preposterous BIOS basemem of %uK, "
                        "truncating to < 640K\n", basemem);
                basemem = 636;
        }

        /*
         * XXX if biosbasemem is now < 640, there is a `hole'
         * between the end of base memory and the start of
         * ISA memory.  The hole may be empty or it may
         * contain BIOS code or data.  Map it read/write so
         * that the BIOS can write to it.  (Memory from 0 to
         * the physical end of the kernel is mapped read-only
         * to begin with and then parts of it are remapped.
         * The parts that aren't remapped form holes that
         * remain read-only and are unused by the kernel.
         * The base memory area is below the physical end of
         * the kernel and right now forms a read-only hole.
         * The part of it from PAGE_SIZE to
         * (trunc_page(biosbasemem * 1024) - 1) will be
         * remapped and used by the kernel later.)
         *
         * This code is similar to the code used in
         * pmap_mapdev, but since no memory needs to be
         * allocated we simply change the mapping.
         */
        for (pa = trunc_page(basemem * 1024);
             pa < ISA_HOLE_START; pa += PAGE_SIZE) {
                pte = vtopte(pa + KERNBASE);
                *pte = pa | PG_RW | PG_V;
        }

        /*
         * if basemem != 640, map pages r/w into vm86 page table so 
         * that the bios can scribble on it.
         */
        pte = vm86paddr;
        for (i = basemem / 4; i < 160; i++)
                pte[i] = (i << PAGE_SHIFT) | PG_V | PG_RW | PG_U;

int15e820:
        /*
         * 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.
         */
        pte = vtopte(KERNBASE + (1 << PAGE_SHIFT));
        *pte = (1 << PAGE_SHIFT) | PG_RW | PG_V;

        /*
         * get memory map with INT 15:E820
         */
#define SMAPSIZ         sizeof(*smap)
#define SMAP_SIG        0x534D4150                      /* 'SMAP' */

        vmc.npages = 0;
        smap = (void *)vm86_addpage(&vmc, 1, KERNBASE + (1 << PAGE_SHIFT));
        vm86_getptr(&vmc, (vm_offset_t)smap, &vmf.vmf_es, &vmf.vmf_di);

        physmap_idx = 0;
        vmf.vmf_ebx = 0;
        do {
                vmf.vmf_eax = 0xE820;
                vmf.vmf_edx = SMAP_SIG;
                vmf.vmf_ecx = SMAPSIZ;
                i = vm86_datacall(0x15, &vmf, &vmc);
                if (i || vmf.vmf_eax != SMAP_SIG)
                        break;
                if (boothowto & RB_VERBOSE)
                        kprintf("SMAP type=%02x base=%08x %08x len=%08x %08x\n",
                                smap->type,
                                *(u_int32_t *)((char *)&smap->base + 4),
                                (u_int32_t)smap->base,
                                *(u_int32_t *)((char *)&smap->length + 4),
                                (u_int32_t)smap->length);

                if (smap->type != 0x01)
                        goto next_run;

                if (smap->length == 0)
                        goto next_run;

                if (smap->base >= 0xffffffff) {
                        kprintf("%uK of memory above 4GB ignored\n",
                            (u_int)(smap->length / 1024));
                        goto next_run;
                }

                for (i = 0; i <= physmap_idx; i += 2) {
                        if (smap->base < physmap[i + 1]) {
                                if (boothowto & RB_VERBOSE)
                                        kprintf(
        "Overlapping or non-montonic memory region, ignoring second region\n");
                                goto next_run;
                        }
                }

                if (smap->base == physmap[physmap_idx + 1]) {
                        physmap[physmap_idx + 1] += smap->length;
                        goto next_run;
                }

                physmap_idx += 2;
                if (physmap_idx == PHYSMAP_ENTRIES*2) {
                        kprintf(
                "Too many segments in the physical address map, giving up\n");
                        break;
                }
                physmap[physmap_idx] = smap->base;
                physmap[physmap_idx + 1] = smap->base + smap->length;
next_run:
                ; /* fix GCC3.x warning */
        } while (vmf.vmf_ebx != 0);

        /*
         * Perform "base memory" related probes & setup based on SMAP
         */
        if (basemem == 0) {
                for (i = 0; i <= physmap_idx; i += 2) {
                        if (physmap[i] == 0x00000000) {
                                basemem = physmap[i + 1] / 1024;
                                break;
                        }
                }

                if (basemem == 0) {
                        basemem = 640;
                }

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

                for (pa = trunc_page(basemem * 1024);
                     pa < ISA_HOLE_START; pa += PAGE_SIZE) {
                        pte = vtopte(pa + KERNBASE);
                        *pte = pa | PG_RW | PG_V;
                }

                pte = vm86paddr;
                for (i = basemem / 4; i < 160; i++)
                        pte[i] = (i << PAGE_SHIFT) | PG_V | PG_RW | PG_U;
        }

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

        /*
         * If we failed above, try memory map with INT 15:E801
         */
        vmf.vmf_ax = 0xE801;
        if (vm86_intcall(0x15, &vmf) == 0) {
                extmem = vmf.vmf_cx + vmf.vmf_dx * 64;
        } else {
#if 0
                vmf.vmf_ah = 0x88;
                vm86_intcall(0x15, &vmf);
                extmem = vmf.vmf_ax;
#else
                /*
                 * Prefer the RTC value for extended memory.
                 */
                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 YYY */
        physmap[1] = mp_bootaddress(physmap[1] / 1024);

        /* look for the MP hardware - needed for apic addresses */
        mp_probe();
#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.
         */
        Maxmem = atop(physmap[physmap_idx + 1]);

#ifdef MAXMEM
        Maxmem = MAXMEM / 4;
#endif

        /*
         * hw.physmem is a size in bytes; we also allow k, m, and g suffixes
         * for the appropriate modifiers.  This overrides MAXMEM.
         */
        if ((cp = kgetenv("hw.physmem")) != NULL) {
                u_int64_t AllowMem, sanity;
                char *ep;

                sanity = AllowMem = strtouq(cp, &ep, 0);
                if ((ep != cp) && (*ep != 0)) {
                        switch(*ep) {
                        case 'g':
                        case 'G':
                                AllowMem <<= 10;
                        case 'm':
                        case 'M':
                                AllowMem <<= 10;
                        case 'k':
                        case 'K':
                                AllowMem <<= 10;
                                break;
                        default:
                                AllowMem = sanity = 0;
                        }
                        if (AllowMem < sanity)
                                AllowMem = 0;
                }
                if (AllowMem == 0)
                        kprintf("Ignoring invalid memory size of '%s'\n", cp);
                else
                        Maxmem = atop(AllowMem);
        }

        if (atop(physmap[physmap_idx + 1]) != Maxmem &&
            (boothowto & RB_VERBOSE))
                kprintf("Physical memory use set to %lluK\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(Maxmem);

        /* call pmap initialization to make new kernel address space */
        pmap_bootstrap(first, 0);

        /*
         * Size up each available chunk of physical memory.
         */
        physmap[0] = PAGE_SIZE;         /* mask off page 0 */
        pa_indx = 0;
        phys_avail[pa_indx++] = physmap[0];
        phys_avail[pa_indx] = physmap[0];
        pte = CMAP1;

        /*
         * Get dcons buffer address
         */
        if (kgetenv_quad("dcons.addr", &dcons_addr) == 0 ||
            kgetenv_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_offset_t end;

                end = ptoa(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;
#if 0
                        int *ptr = 0;
#else
                        int *ptr = (int *)CADDR1;
#endif

                        /*
                         * block out kernel memory as not available.
                         */
                        if (pa >= 0x100000 && pa < first)
                                continue;
        
                        /*
                         * block out dcons buffer
                         */
                        if (dcons_addr > 0
                            && pa >= trunc_page(dcons_addr)
                            && pa < dcons_addr + dcons_size)
                                continue;

                        page_bad = FALSE;

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

                        /*
                         * 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 >= PHYSMAP_ENTRIES*2) {
                                        kprintf("Too many holes in the physical address space, giving up\n");
                                        pa_indx--;
                                        break;
                                }
                                phys_avail[pa_indx++] = pa;     /* start */
                                phys_avail[pa_indx] = pa + PAGE_SIZE;   /* end */
                        }
                        physmem++;
                }
        }
        *pte = 0;
        cpu_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(MSGBUF_SIZE) >= 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(MSGBUF_SIZE);

        avail_end = phys_avail[pa_indx];
}

/*
 * IDT VECTORS:
 *      0       Divide by zero
 *      1       Debug
 *      2       NMI
 *      3       BreakPoint
 *      4       OverFlow
 *      5       Bound-Range
 *      6       Invalid OpCode
 *      7       Device Not Available (x87)
 *      8       Double-Fault
 *      9       Coprocessor Segment overrun (unsupported, reserved)
 *      10      Invalid-TSS
 *      11      Segment not present
 *      12      Stack
 *      13      General Protection
 *      14      Page Fault
 *      15      Reserved
 *      16      x87 FP Exception pending
 *      17      Alignment Check
 *      18      Machine Check
 *      19      SIMD floating point
 *      20-31   reserved
 *      32-255  INTn/external sources
 */
void
init386(int first)
{
        struct gate_descriptor *gdp;
        int gsel_tss, metadata_missing, off, x;
        struct mdglobaldata *gd;

        /*
         * Prevent lowering of the ipl if we call tsleep() early.
         */
        gd = &CPU_prvspace[0].mdglobaldata;
        bzero(gd, sizeof(*gd));

        gd->mi.gd_curthread = &thread0;
        thread0.td_gd = &gd->mi;

        atdevbase = ISA_HOLE_START + KERNBASE;

        metadata_missing = 0;
        if (bootinfo.bi_modulep) {
                preload_metadata = (caddr_t)bootinfo.bi_modulep + KERNBASE;
                preload_bootstrap_relocate(KERNBASE);
        } else {
                metadata_missing = 1;
        }
        if (bootinfo.bi_envp)
                kern_envp = (caddr_t)bootinfo.bi_envp + KERNBASE;

        /*
         * start with one cpu.  Note: with one cpu, ncpus2_shift, ncpus2_mask,
         * and ncpus_fit_mask remain 0.
         */
        ncpus = 1;
        ncpus2 = 1;
        ncpus_fit = 1;
        /* Init basic tunables, hz etc */
        init_param1();

        /*
         * make gdt memory segments, the code segment goes up to end of the
         * page with etext in it, the data segment goes to the end of
         * the address space
         */
        /*
         * XXX text protection is temporarily (?) disabled.  The limit was
         * i386_btop(round_page(etext)) - 1.
         */
        gdt_segs[GCODE_SEL].ssd_limit = atop(0 - 1);
        gdt_segs[GDATA_SEL].ssd_limit = atop(0 - 1);

        gdt_segs[GPRIV_SEL].ssd_limit =
                atop(sizeof(struct privatespace) - 1);
        gdt_segs[GPRIV_SEL].ssd_base = (int) &CPU_prvspace[0];
        gdt_segs[GPROC0_SEL].ssd_base =
                (int) &CPU_prvspace[0].mdglobaldata.gd_common_tss;

        gd->mi.gd_prvspace = &CPU_prvspace[0];

        /*
         * Note: on both UP and SMP curthread must be set non-NULL
         * early in the boot sequence because the system assumes
         * that 'curthread' is never NULL.
         */

        for (x = 0; x < NGDT; x++) {
#ifdef BDE_DEBUGGER
                /* avoid overwriting db entries with APM ones */
                if (x >= GAPMCODE32_SEL && x <= GAPMDATA_SEL)
                        continue;
#endif
                ssdtosd(&gdt_segs[x], &gdt[x].sd);
        }

        r_gdt.rd_limit = NGDT * sizeof(gdt[0]) - 1;
        r_gdt.rd_base =  (int) gdt;
        lgdt(&r_gdt);

        mi_gdinit(&gd->mi, 0);
        cpu_gdinit(gd, 0);
        mi_proc0init(&gd->mi, proc0paddr);
        safepri = TDPRI_MAX;

        /* make ldt memory segments */
        /*
         * XXX - VM_MAX_USER_ADDRESS is an end address, not a max.  And it
         * should be spelled ...MAX_USER...
         */
        ldt_segs[LUCODE_SEL].ssd_limit = atop(VM_MAX_USER_ADDRESS - 1);
        ldt_segs[LUDATA_SEL].ssd_limit = atop(VM_MAX_USER_ADDRESS - 1);
        for (x = 0; x < sizeof ldt_segs / sizeof ldt_segs[0]; x++)
                ssdtosd(&ldt_segs[x], &ldt[x].sd);

        _default_ldt = GSEL(GLDT_SEL, SEL_KPL);
        lldt(_default_ldt);
        gd->gd_currentldt = _default_ldt;
        /* spinlocks and the BGL */
        init_locks();

        /*
         * Setup the hardware exception table.  Most exceptions use
         * SDT_SYS386TGT, known as a 'trap gate'.  Trap gates leave
         * interrupts enabled.  VM page faults use SDT_SYS386IGT, known as
         * an 'interrupt trap gate', which disables interrupts on entry,
         * in order to be able to poll the appropriate CRn register to
         * determine the fault address.
         */
        for (x = 0; x < NIDT; x++) {
#ifdef DEBUG_INTERRUPTS
                setidt(x, Xrsvdary[x], SDT_SYS386TGT, SEL_KPL, GSEL(GCODE_SEL, SEL_KPL));
#else
                setidt(x, &IDTVEC(rsvd0), SDT_SYS386TGT, SEL_KPL, GSEL(GCODE_SEL, SEL_KPL));
#endif
        }
        setidt(0, &IDTVEC(div),  SDT_SYS386TGT, SEL_KPL, GSEL(GCODE_SEL, SEL_KPL));
        setidt(1, &IDTVEC(dbg),  SDT_SYS386TGT, SEL_KPL, GSEL(GCODE_SEL, SEL_KPL));
        setidt(2, &IDTVEC(nmi),  SDT_SYS386TGT, SEL_KPL, GSEL(GCODE_SEL, SEL_KPL));
        setidt(3, &IDTVEC(bpt),  SDT_SYS386TGT, SEL_UPL, GSEL(GCODE_SEL, SEL_KPL));
        setidt(4, &IDTVEC(ofl),  SDT_SYS386TGT, SEL_UPL, GSEL(GCODE_SEL, SEL_KPL));
        setidt(5, &IDTVEC(bnd),  SDT_SYS386TGT, SEL_KPL, GSEL(GCODE_SEL, SEL_KPL));
        setidt(6, &IDTVEC(ill),  SDT_SYS386TGT, SEL_KPL, GSEL(GCODE_SEL, SEL_KPL));
        setidt(7, &IDTVEC(dna),  SDT_SYS386TGT, SEL_KPL, GSEL(GCODE_SEL, SEL_KPL));
        setidt(8, 0,  SDT_SYSTASKGT, SEL_KPL, GSEL(GPANIC_SEL, SEL_KPL));
        setidt(9, &IDTVEC(fpusegm),  SDT_SYS386TGT, SEL_KPL, GSEL(GCODE_SEL, SEL_KPL));
        setidt(10, &IDTVEC(tss),  SDT_SYS386TGT, SEL_KPL, GSEL(GCODE_SEL, SEL_KPL));
        setidt(11, &IDTVEC(missing),  SDT_SYS386TGT, SEL_KPL, GSEL(GCODE_SEL, SEL_KPL));
        setidt(12, &IDTVEC(stk),  SDT_SYS386TGT, SEL_KPL, GSEL(GCODE_SEL, SEL_KPL));
        setidt(13, &IDTVEC(prot),  SDT_SYS386TGT, SEL_KPL, GSEL(GCODE_SEL, SEL_KPL));
        setidt(14, &IDTVEC(page),  SDT_SYS386IGT, SEL_KPL, GSEL(GCODE_SEL, SEL_KPL));
        setidt(15, &IDTVEC(rsvd0),  SDT_SYS386TGT, SEL_KPL, GSEL(GCODE_SEL, SEL_KPL));
        setidt(16, &IDTVEC(fpu),  SDT_SYS386TGT, SEL_KPL, GSEL(GCODE_SEL, SEL_KPL));
        setidt(17, &IDTVEC(align), SDT_SYS386TGT, SEL_KPL, GSEL(GCODE_SEL, SEL_KPL));
        setidt(18, &IDTVEC(mchk),  SDT_SYS386TGT, SEL_KPL, GSEL(GCODE_SEL, SEL_KPL));
        setidt(19, &IDTVEC(xmm), SDT_SYS386TGT, SEL_KPL, GSEL(GCODE_SEL, SEL_KPL));
        setidt(0x80, &IDTVEC(int0x80_syscall),
                        SDT_SYS386TGT, SEL_UPL, GSEL(GCODE_SEL, SEL_KPL));

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

        /*
         * Initialize the console before we print anything out.
         */
        cninit();

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

#if     NISA >0
        isa_defaultirq();
#endif
        rand_initialize();

#ifdef DDB
        kdb_init();
        if (boothowto & RB_KDB)
                Debugger("Boot flags requested debugger");
#endif

        finishidentcpu();       /* Final stage of CPU initialization */
        setidt(6, &IDTVEC(ill),  SDT_SYS386TGT, SEL_KPL, GSEL(GCODE_SEL, SEL_KPL));
        setidt(13, &IDTVEC(prot),  SDT_SYS386TGT, SEL_KPL, GSEL(GCODE_SEL, SEL_KPL));
        initializecpu();        /* Initialize CPU registers */

        /*
         * make an initial tss so cpu can get interrupt stack on syscall!
         * The 16 bytes is to save room for a VM86 context.
         */
        gd->gd_common_tss.tss_esp0 = (int) thread0.td_pcb - 16;
        gd->gd_common_tss.tss_ss0 = GSEL(GDATA_SEL, SEL_KPL) ;
        gsel_tss = GSEL(GPROC0_SEL, SEL_KPL);
        gd->gd_tss_gdt = &gdt[GPROC0_SEL].sd;
        gd->gd_common_tssd = *gd->gd_tss_gdt;
        gd->gd_common_tss.tss_ioopt = (sizeof gd->gd_common_tss) << 16;
        ltr(gsel_tss);

        dblfault_tss.tss_esp = dblfault_tss.tss_esp0 = dblfault_tss.tss_esp1 =
            dblfault_tss.tss_esp2 = (int) &dblfault_stack[sizeof(dblfault_stack)];
        dblfault_tss.tss_ss = dblfault_tss.tss_ss0 = dblfault_tss.tss_ss1 =
            dblfault_tss.tss_ss2 = GSEL(GDATA_SEL, SEL_KPL);
        dblfault_tss.tss_cr3 = (int)IdlePTD;
        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);

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

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

        /* Map the message buffer. */
        for (off = 0; off < round_page(MSGBUF_SIZE); off += PAGE_SIZE)
                pmap_kenter((vm_offset_t)msgbufp + off, avail_end + off);

        msgbufinit(msgbufp, MSGBUF_SIZE);

        /* make a call gate to reenter kernel with */
        gdp = &ldt[LSYS5CALLS_SEL].gd;

        x = (int) &IDTVEC(syscall);
        gdp->gd_looffset = x++;
        gdp->gd_selector = GSEL(GCODE_SEL,SEL_KPL);
        gdp->gd_stkcpy = 1;
        gdp->gd_type = SDT_SYS386CGT;
        gdp->gd_dpl = SEL_UPL;
        gdp->gd_p = 1;
        gdp->gd_hioffset = ((int) &IDTVEC(syscall)) >>16;

        /* XXX does this work? */
        ldt[LBSDICALLS_SEL] = ldt[LSYS5CALLS_SEL];
        ldt[LSOL26CALLS_SEL] = ldt[LSYS5CALLS_SEL];

        /* transfer to user mode */

        _ucodesel = LSEL(LUCODE_SEL, SEL_UPL);
        _udatasel = LSEL(LUDATA_SEL, SEL_UPL);

        /* setup proc 0's pcb */
        thread0.td_pcb->pcb_flags = 0;
        thread0.td_pcb->pcb_cr3 = (int)IdlePTD; /* should already be setup */
        thread0.td_pcb->pcb_ext = 0;
        lwp0.lwp_md.md_regs = &proc0_tf;
}

/*
 * Initialize machine-dependant portions of the global data structure.
 * Note that the global data area and cpu0's idlestack in the private
 * data space were allocated in locore.
 *
 * Note: the idlethread's cpl is 0
 *
 * WARNING!  Called from early boot, 'mycpu' may not work yet.
 */
void
cpu_gdinit(struct mdglobaldata *gd, int cpu)
{
        if (cpu)
                gd->mi.gd_curthread = &gd->mi.gd_idlethread;

        lwkt_init_thread(&gd->mi.gd_idlethread, 
                        gd->mi.gd_prvspace->idlestack, 
                        sizeof(gd->mi.gd_prvspace->idlestack), 
                        TDF_MPSAFE, &gd->mi);
        lwkt_set_comm(&gd->mi.gd_idlethread, "idle_%d", cpu);
        gd->mi.gd_idlethread.td_switch = cpu_lwkt_switch;
        gd->mi.gd_idlethread.td_sp -= sizeof(void *);
        *(void **)gd->mi.gd_idlethread.td_sp = cpu_idle_restore;
}

int
is_globaldata_space(vm_offset_t saddr, vm_offset_t eaddr)
{
        if (saddr >= (vm_offset_t)&CPU_prvspace[0] &&
            eaddr <= (vm_offset_t)&CPU_prvspace[MAXCPU]) {
                return (TRUE);
        }
        return (FALSE);
}

struct globaldata *
globaldata_find(int cpu)
{
        KKASSERT(cpu >= 0 && cpu < ncpus);
        return(&CPU_prvspace[cpu].mdglobaldata.mi);
}

#if defined(I586_CPU) && !defined(NO_F00F_HACK)
static void f00f_hack(void *unused);
SYSINIT(f00f_hack, SI_BOOT2_BIOS, SI_ORDER_ANY, f00f_hack, NULL);

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

        if (!has_f00f_bug)
                return;

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

        r_idt.rd_limit = sizeof(idt0) - 1;

        tmp = kmem_alloc(&kernel_map, PAGE_SIZE * 2);
        if (tmp == 0)
                panic("kmem_alloc returned 0");
        if (((unsigned int)tmp & (PAGE_SIZE-1)) != 0)
                panic("kmem_alloc returned non-page-aligned memory");
        /* Put the first seven entries in the lower page */
        new_idt = (struct gate_descriptor*)(tmp + PAGE_SIZE - (7*8));
        bcopy(idt, new_idt, sizeof(idt0));
        r_idt.rd_base = (int)new_idt;
        lidt(&r_idt);
        idt = new_idt;
        if (vm_map_protect(&kernel_map, tmp, tmp + PAGE_SIZE,
                           VM_PROT_READ, FALSE) != KERN_SUCCESS)
                panic("vm_map_protect failed");
        return;
}
#endif /* defined(I586_CPU) && !NO_F00F_HACK */

int
ptrace_set_pc(struct lwp *lp, unsigned long addr)
{
        lp->lwp_md.md_regs->tf_eip = addr;
        return (0);
}

int
ptrace_single_step(struct lwp *lp)
{
        lp->lwp_md.md_regs->tf_eflags |= PSL_T;
        return (0);
}

int
fill_regs(struct lwp *lp, struct reg *regs)
{
        struct pcb *pcb;
        struct trapframe *tp;

        tp = lp->lwp_md.md_regs;
        regs->r_gs = tp->tf_gs;
        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;
        pcb = lp->lwp_thread->td_pcb;
        return (0);
}

int
set_regs(struct lwp *lp, struct reg *regs)
{
        struct pcb *pcb;
        struct trapframe *tp;

        tp = lp->lwp_md.md_regs;
        if (!EFL_SECURE(regs->r_eflags, tp->tf_eflags) ||
            !CS_SECURE(regs->r_cs))
                return (EINVAL);
        tp->tf_gs = regs->r_gs;
        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 = lp->lwp_thread->td_pcb;
        return (0);
}

#ifndef CPU_DISABLE_SSE
static void
fill_fpregs_xmm(struct savexmm *sv_xmm, struct save87 *sv_87)
{
        struct env87 *penv_87 = &sv_87->sv_env;
        struct envxmm *penv_xmm = &sv_xmm->sv_env;
        int i;

        /* FPU control/status */
        penv_87->en_cw = penv_xmm->en_cw;
        penv_87->en_sw = penv_xmm->en_sw;
        penv_87->en_tw = penv_xmm->en_tw;
        penv_87->en_fip = penv_xmm->en_fip;
        penv_87->en_fcs = penv_xmm->en_fcs;
        penv_87->en_opcode = penv_xmm->en_opcode;
        penv_87->en_foo = penv_xmm->en_foo;
        penv_87->en_fos = penv_xmm->en_fos;

        /* FPU registers */
        for (i = 0; i < 8; ++i)
                sv_87->sv_ac[i] = sv_xmm->sv_fp[i].fp_acc;

        sv_87->sv_ex_sw = sv_xmm->sv_ex_sw;
}

static void
set_fpregs_xmm(struct save87 *sv_87, struct savexmm *sv_xmm)
{
        struct env87 *penv_87 = &sv_87->sv_env;
        struct envxmm *penv_xmm = &sv_xmm->sv_env;
        int i;

        /* FPU control/status */
        penv_xmm->en_cw = penv_87->en_cw;
        penv_xmm->en_sw = penv_87->en_sw;
        penv_xmm->en_tw = penv_87->en_tw;
        penv_xmm->en_fip = penv_87->en_fip;
        penv_xmm->en_fcs = penv_87->en_fcs;
        penv_xmm->en_opcode = penv_87->en_opcode;
        penv_xmm->en_foo = penv_87->en_foo;
        penv_xmm->en_fos = penv_87->en_fos;

        /* FPU registers */
        for (i = 0; i < 8; ++i)
                sv_xmm->sv_fp[i].fp_acc = sv_87->sv_ac[i];

        sv_xmm->sv_ex_sw = sv_87->sv_ex_sw;
}
#endif /* CPU_DISABLE_SSE */

int
fill_fpregs(struct lwp *lp, struct fpreg *fpregs)
{
#ifndef CPU_DISABLE_SSE
        if (cpu_fxsr) {
                fill_fpregs_xmm(&lp->lwp_thread->td_pcb->pcb_save.sv_xmm,
                                (struct save87 *)fpregs);
                return (0);
        }
#endif /* CPU_DISABLE_SSE */
        bcopy(&lp->lwp_thread->td_pcb->pcb_save.sv_87, fpregs, sizeof *fpregs);
        return (0);
}

int
set_fpregs(struct lwp *lp, struct fpreg *fpregs)
{
#ifndef CPU_DISABLE_SSE
        if (cpu_fxsr) {
                set_fpregs_xmm((struct save87 *)fpregs,
                               &lp->lwp_thread->td_pcb->pcb_save.sv_xmm);
                return (0);
        }
#endif /* CPU_DISABLE_SSE */
        bcopy(fpregs, &lp->lwp_thread->td_pcb->pcb_save.sv_87, sizeof *fpregs);
        return (0);
}

int
fill_dbregs(struct lwp *lp, struct dbreg *dbregs)
{
        if (lp == NULL) {
                dbregs->dr0 = rdr0();
                dbregs->dr1 = rdr1();
                dbregs->dr2 = rdr2();
                dbregs->dr3 = rdr3();
                dbregs->dr4 = rdr4();
                dbregs->dr5 = rdr5();
                dbregs->dr6 = rdr6();
                dbregs->dr7 = rdr7();
        } else {
                struct pcb *pcb;

                pcb = lp->lwp_thread->td_pcb;
                dbregs->dr0 = pcb->pcb_dr0;
                dbregs->dr1 = pcb->pcb_dr1;
                dbregs->dr2 = pcb->pcb_dr2;
                dbregs->dr3 = pcb->pcb_dr3;
                dbregs->dr4 = 0;
                dbregs->dr5 = 0;
                dbregs->dr6 = pcb->pcb_dr6;
                dbregs->dr7 = pcb->pcb_dr7;
        }
        return (0);
}

int
set_dbregs(struct lwp *lp, struct dbreg *dbregs)
{
        if (lp == NULL) {
                load_dr0(dbregs->dr0);
                load_dr1(dbregs->dr1);
                load_dr2(dbregs->dr2);
                load_dr3(dbregs->dr3);
                load_dr4(dbregs->dr4);
                load_dr5(dbregs->dr5);
                load_dr6(dbregs->dr6);
                load_dr7(dbregs->dr7);
        } else {
                struct pcb *pcb;
                struct ucred *ucred;
                int i;
                uint32_t mask1, mask2;

                /*
                 * 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, mask1 = 0x3<<16, mask2 = 0x2<<16; i < 8; 
                     i++, mask1 <<= 2, mask2 <<= 2)
                        if ((dbregs->dr7 & mask1) == mask2)
                                return (EINVAL);
                
                pcb = lp->lwp_thread->td_pcb;
                ucred = lp->lwp_proc->p_ucred;

                /*
                 * 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, unless, perhaps, we were called by
                 * uid 0.
                 *
                 * 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 (suser_cred(ucred, 0) != 0) {
                        if (dbregs->dr7 & 0x3) {
                                /* dr0 is enabled */
                                if (dbregs->dr0 >= VM_MAX_USER_ADDRESS)
                                        return (EINVAL);
                        }

                        if (dbregs->dr7 & (0x3<<2)) {
                                /* dr1 is enabled */
                                if (dbregs->dr1 >= VM_MAX_USER_ADDRESS)
                                        return (EINVAL);
                        }

                        if (dbregs->dr7 & (0x3<<4)) {
                                /* dr2 is enabled */
                                if (dbregs->dr2 >= VM_MAX_USER_ADDRESS)
                                        return (EINVAL);
                        }

                        if (dbregs->dr7 & (0x3<<6)) {
                                /* dr3 is enabled */
                                if (dbregs->dr3 >= VM_MAX_USER_ADDRESS)
                                        return (EINVAL);
                        }
                }

                pcb->pcb_dr0 = dbregs->dr0;
                pcb->pcb_dr1 = dbregs->dr1;
                pcb->pcb_dr2 = dbregs->dr2;
                pcb->pcb_dr3 = dbregs->dr3;
                pcb->pcb_dr6 = dbregs->dr6;
                pcb->pcb_dr7 = dbregs->dr7;

                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(void)
{
        u_int32_t dr7, dr6; /* debug registers dr6 and 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;
        
        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;
        dr6 = rdr6();
        bp = dr6 & 0x0000000f;

        if (!bp) {
                /*
                 * None of the breakpoint bits are set meaning this
                 * trap was not caused by any of the debug registers
                 */
                return 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_MAX_USER_ADDRESS) {
                        /*
                         * addr[i] is in user space
                         */
                        return nbp;
                }
        }

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


#ifndef DDB
void
Debugger(const char *msg)
{
        kprintf("Debugger(\"%s\") called.\n", msg);
}
#endif /* no DDB */

#ifdef DDB

/*
 * Provide inb() and outb() as functions.  They are normally only
 * available as macros calling inlined functions, thus cannot be
 * called inside DDB.
 *
 * The actual code is stolen from <machine/cpufunc.h>, and de-inlined.
 */

#undef inb
#undef outb

/* silence compiler warnings */
u_char inb(u_int);
void outb(u_int, u_char);

u_char
inb(u_int port)
{
        u_char  data;
        /*
         * We use %%dx and not %1 here because i/o is done at %dx and not at
         * %edx, while gcc generates inferior code (movw instead of movl)
         * if we tell it to load (u_short) port.
         */
        __asm __volatile("inb %%dx,%0" : "=a" (data) : "d" (port));
        return (data);
}

void
outb(u_int port, u_char data)
{
        u_char  al;
        /*
         * Use an unnecessary assignment to help gcc's register allocator.
         * This make a large difference for gcc-1.40 and a tiny difference
         * for gcc-2.6.0.  For gcc-1.40, al had to be ``asm("ax")'' for
         * best results.  gcc-2.6.0 can't handle this.
         */
        al = data;
        __asm __volatile("outb %0,%%dx" : : "a" (al), "d" (port));
}

#endif /* DDB */



#include "opt_cpu.h"


/*
 * initialize all the SMP locks
 */

/* critical region when masking or unmasking interupts */
struct spinlock_deprecated imen_spinlock;

/* Make FAST_INTR() routines sequential */
struct spinlock_deprecated fast_intr_spinlock;

/* critical region for old style disable_intr/enable_intr */
struct spinlock_deprecated mpintr_spinlock;

/* critical region around INTR() routines */
struct spinlock_deprecated intr_spinlock;

/* lock region used by kernel profiling */
struct spinlock_deprecated mcount_spinlock;

/* locks com (tty) data/hardware accesses: a FASTINTR() */
struct spinlock_deprecated com_spinlock;

/* locks kernel kprintfs */
struct spinlock_deprecated cons_spinlock;

/* lock regions around the clock hardware */
struct spinlock_deprecated clock_spinlock;

/* lock around the MP rendezvous */
struct spinlock_deprecated smp_rv_spinlock;

static void
init_locks(void)
{
        /*
         * mp_lock = 0; BSP already owns the MP lock 
         */
        /*
         * Get the initial mp_lock with a count of 1 for the BSP.
         * This uses a LOGICAL cpu ID, ie BSP == 0.
         */
#ifdef SMP
        cpu_get_initial_mplock();
#endif
        /* DEPRECATED */
        spin_lock_init(&mcount_spinlock);
        spin_lock_init(&fast_intr_spinlock);
        spin_lock_init(&intr_spinlock);
        spin_lock_init(&mpintr_spinlock);
        spin_lock_init(&imen_spinlock);
        spin_lock_init(&smp_rv_spinlock);
        spin_lock_init(&com_spinlock);
        spin_lock_init(&clock_spinlock);
        spin_lock_init(&cons_spinlock);

        /* our token pool needs to work early */
        lwkt_token_pool_init();
}