FreeBSD/Linux Kernel Cross Reference
sys/amd64/amd64/machdep.c

     /*-
      * Copyright (c) 2003 Peter Wemm.
      * 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
     */
    
    #include <sys/cdefs.h>
    __FBSDID("$FreeBSD$");
    
    #include "opt_atpic.h"
    #include "opt_compat.h"
    #include "opt_cpu.h"
    #include "opt_ddb.h"
    #include "opt_inet.h"
    #include "opt_isa.h"
    #include "opt_kstack_pages.h"
    #include "opt_maxmem.h"
    #include "opt_mp_watchdog.h"
    #include "opt_perfmon.h"
    #include "opt_platform.h"
    #include "opt_sched.h"
    
    #include <sys/param.h>
    #include <sys/proc.h>
    #include <sys/systm.h>
    #include <sys/bio.h>
    #include <sys/buf.h>
    #include <sys/bus.h>
    #include <sys/callout.h>
    #include <sys/cons.h>
    #include <sys/cpu.h>
    #include <sys/efi.h>
    #include <sys/eventhandler.h>
    #include <sys/exec.h>
    #include <sys/imgact.h>
    #include <sys/kdb.h>
    #include <sys/kernel.h>
    #include <sys/ktr.h>
    #include <sys/linker.h>
    #include <sys/lock.h>
    #include <sys/malloc.h>
    #include <sys/memrange.h>
    #include <sys/msgbuf.h>
    #include <sys/mutex.h>
    #include <sys/pcpu.h>
    #include <sys/ptrace.h>
    #include <sys/reboot.h>
    #include <sys/rwlock.h>
    #include <sys/sched.h>
    #include <sys/signalvar.h>
    #ifdef SMP
    #include <sys/smp.h>
    #endif
    #include <sys/syscallsubr.h>
    #include <sys/sysctl.h>
    #include <sys/sysent.h>
    #include <sys/sysproto.h>
    #include <sys/ucontext.h>
    #include <sys/vmmeter.h>
    
    #include <vm/vm.h>
    #include <vm/vm_extern.h>
    #include <vm/vm_kern.h>
    #include <vm/vm_page.h>
    #include <vm/vm_map.h>
   #include <vm/vm_object.h>
   #include <vm/vm_pager.h>
   #include <vm/vm_param.h>
   #include <vm/vm_phys.h>
   
   #ifdef DDB
   #ifndef KDB
   #error KDB must be enabled in order for DDB to work!
   #endif
   #include <ddb/ddb.h>
   #include <ddb/db_sym.h>
   #endif
   
   #include <net/netisr.h>
   
   #include <machine/clock.h>
   #include <machine/cpu.h>
   #include <machine/cputypes.h>
   #include <machine/frame.h>
   #include <machine/intr_machdep.h>
   #include <x86/mca.h>
   #include <machine/md_var.h>
   #include <machine/metadata.h>
   #include <machine/mp_watchdog.h>
   #include <machine/pc/bios.h>
   #include <machine/pcb.h>
   #include <machine/proc.h>
   #include <machine/reg.h>
   #include <machine/sigframe.h>
   #include <machine/specialreg.h>
   #ifdef PERFMON
   #include <machine/perfmon.h>
   #endif
   #include <machine/tss.h>
   #include <x86/ucode.h>
   #ifdef SMP
   #include <machine/smp.h>
   #endif
   #ifdef FDT
   #include <x86/fdt.h>
   #endif
   
   #ifdef DEV_ATPIC
   #include <x86/isa/icu.h>
   #else
   #include <x86/apicvar.h>
   #endif
   
   #include <isa/isareg.h>
   #include <isa/rtc.h>
   #include <x86/init.h>
   
   /* Sanity check for __curthread() */
   CTASSERT(offsetof(struct pcpu, pc_curthread) == 0);
   
   /*
    * The PTI trampoline stack needs enough space for a hardware trapframe and a
    * couple of scratch registers, as well as the trapframe left behind after an
    * iret fault.
    */
   CTASSERT(PC_PTI_STACK_SZ * sizeof(register_t) >= 2 * sizeof(struct pti_frame) -
       offsetof(struct pti_frame, pti_rip));
   
   extern u_int64_t hammer_time(u_int64_t, u_int64_t);
   
   #define CS_SECURE(cs)           (ISPL(cs) == SEL_UPL)
   #define EFL_SECURE(ef, oef)     ((((ef) ^ (oef)) & ~PSL_USERCHANGE) == 0)
   
   static void cpu_startup(void *);
   static void get_fpcontext(struct thread *td, mcontext_t *mcp,
       char *xfpusave, size_t xfpusave_len);
   static int  set_fpcontext(struct thread *td, mcontext_t *mcp,
       char *xfpustate, size_t xfpustate_len);
   SYSINIT(cpu, SI_SUB_CPU, SI_ORDER_FIRST, cpu_startup, NULL);
   
   /* Preload data parse function */
   static caddr_t native_parse_preload_data(u_int64_t);
   
   /* Native function to fetch and parse the e820 map */
   static void native_parse_memmap(caddr_t, vm_paddr_t *, int *);
   
   /* Default init_ops implementation. */
   struct init_ops init_ops = {
           .parse_preload_data =   native_parse_preload_data,
           .early_clock_source_init =      i8254_init,
           .early_delay =                  i8254_delay,
           .parse_memmap =                 native_parse_memmap,
   #ifdef SMP
           .mp_bootaddress =               mp_bootaddress,
           .start_all_aps =                native_start_all_aps,
   #endif
           .msi_init =                     msi_init,
   };
   
   struct msgbuf *msgbufp;
   
   /*
    * Physical address of the EFI System Table. Stashed from the metadata hints
    * passed into the kernel and used by the EFI code to call runtime services.
    */
   vm_paddr_t efi_systbl_phys;
   
   /* Intel ICH registers */
   #define ICH_PMBASE      0x400
   #define ICH_SMI_EN      ICH_PMBASE + 0x30
   
   int     _udatasel, _ucodesel, _ucode32sel, _ufssel, _ugssel;
   
   int cold = 1;
   
   long Maxmem = 0;
   long realmem = 0;
   
   /*
    * The number of PHYSMAP entries must be one less than the number of
    * PHYSSEG entries because the PHYSMAP entry that spans the largest
    * physical address that is accessible by ISA DMA is split into two
    * PHYSSEG entries.
    */
   #define PHYSMAP_SIZE    (2 * (VM_PHYSSEG_MAX - 1))
   
   vm_paddr_t phys_avail[PHYSMAP_SIZE + 2];
   vm_paddr_t dump_avail[PHYSMAP_SIZE + 2];
   
   /* must be 2 less so 0 0 can signal end of chunks */
   #define PHYS_AVAIL_ARRAY_END (nitems(phys_avail) - 2)
   #define DUMP_AVAIL_ARRAY_END (nitems(dump_avail) - 2)
   
   struct kva_md_info kmi;
   
   static struct trapframe proc0_tf;
   struct region_descriptor r_gdt, r_idt;
   
   struct pcpu __pcpu[MAXCPU];
   
   struct mtx icu_lock;
   
   struct mem_range_softc mem_range_softc;
   
   struct mtx dt_lock;     /* lock for GDT and LDT */
   
   void (*vmm_resume_p)(void);
   
   static void
   cpu_startup(dummy)
           void *dummy;
   {
           uintmax_t memsize;
           char *sysenv;
   
           /*
            * On MacBooks, we need to disallow the legacy USB circuit to
            * generate an SMI# because this can cause several problems,
            * namely: incorrect CPU frequency detection and failure to
            * start the APs.
            * We do this by disabling a bit in the SMI_EN (SMI Control and
            * Enable register) of the Intel ICH LPC Interface Bridge. 
            */
           sysenv = kern_getenv("smbios.system.product");
           if (sysenv != NULL) {
                   if (strncmp(sysenv, "MacBook1,1", 10) == 0 ||
                       strncmp(sysenv, "MacBook3,1", 10) == 0 ||
                       strncmp(sysenv, "MacBook4,1", 10) == 0 ||
                       strncmp(sysenv, "MacBookPro1,1", 13) == 0 ||
                       strncmp(sysenv, "MacBookPro1,2", 13) == 0 ||
                       strncmp(sysenv, "MacBookPro3,1", 13) == 0 ||
                       strncmp(sysenv, "MacBookPro4,1", 13) == 0 ||
                       strncmp(sysenv, "Macmini1,1", 10) == 0) {
                           if (bootverbose)
                                   printf("Disabling LEGACY_USB_EN bit on "
                                       "Intel ICH.\n");
                           outl(ICH_SMI_EN, inl(ICH_SMI_EN) & ~0x8);
                   }
                   freeenv(sysenv);
           }
   
           /*
            * Good {morning,afternoon,evening,night}.
            */
           startrtclock();
           printcpuinfo();
   #ifdef PERFMON
           perfmon_init();
   #endif
   
           /*
            * Display physical memory if SMBIOS reports reasonable amount.
            */
           memsize = 0;
           sysenv = kern_getenv("smbios.memory.enabled");
           if (sysenv != NULL) {
                   memsize = (uintmax_t)strtoul(sysenv, (char **)NULL, 10) << 10;
                   freeenv(sysenv);
           }
           if (memsize < ptoa((uintmax_t)vm_cnt.v_free_count))
                   memsize = ptoa((uintmax_t)Maxmem);
           printf("real memory  = %ju (%ju MB)\n", memsize, memsize >> 20);
           realmem = atop(memsize);
   
           /*
            * Display any holes after the first chunk of extended memory.
            */
           if (bootverbose) {
                   int indx;
   
                   printf("Physical memory chunk(s):\n");
                   for (indx = 0; phys_avail[indx + 1] != 0; indx += 2) {
                           vm_paddr_t size;
   
                           size = phys_avail[indx + 1] - phys_avail[indx];
                           printf(
                               "0x%016jx - 0x%016jx, %ju bytes (%ju pages)\n",
                               (uintmax_t)phys_avail[indx],
                               (uintmax_t)phys_avail[indx + 1] - 1,
                               (uintmax_t)size, (uintmax_t)size / PAGE_SIZE);
                   }
           }
   
           vm_ksubmap_init(&kmi);
   
           printf("avail memory = %ju (%ju MB)\n",
               ptoa((uintmax_t)vm_cnt.v_free_count),
               ptoa((uintmax_t)vm_cnt.v_free_count) / 1048576);
   
           /*
            * Set up buffers, so they can be used to read disk labels.
            */
           bufinit();
           vm_pager_bufferinit();
   
           cpu_setregs();
   }
   
   /*
    * Send an interrupt to process.
    *
    * Stack is set up to allow sigcode stored
    * at top to call routine, followed by call
    * to sigreturn routine below.  After sigreturn
    * resets the signal mask, the stack, and the
    * frame pointer, it returns to the user
    * specified pc, psl.
    */
   void
   sendsig(sig_t catcher, ksiginfo_t *ksi, sigset_t *mask)
   {
           struct sigframe sf, *sfp;
           struct pcb *pcb;
           struct proc *p;
           struct thread *td;
           struct sigacts *psp;
           char *sp;
           struct trapframe *regs;
           char *xfpusave;
           size_t xfpusave_len;
           int sig;
           int oonstack;
   
           td = curthread;
           pcb = td->td_pcb;
           p = td->td_proc;
           PROC_LOCK_ASSERT(p, MA_OWNED);
           sig = ksi->ksi_signo;
           psp = p->p_sigacts;
           mtx_assert(&psp->ps_mtx, MA_OWNED);
           regs = td->td_frame;
           oonstack = sigonstack(regs->tf_rsp);
   
           if (cpu_max_ext_state_size > sizeof(struct savefpu) && use_xsave) {
                   xfpusave_len = cpu_max_ext_state_size - sizeof(struct savefpu);
                   xfpusave = __builtin_alloca(xfpusave_len);
           } else {
                   xfpusave_len = 0;
                   xfpusave = NULL;
           }
   
           /* Save user context. */
           bzero(&sf, sizeof(sf));
           sf.sf_uc.uc_sigmask = *mask;
           sf.sf_uc.uc_stack = td->td_sigstk;
           sf.sf_uc.uc_stack.ss_flags = (td->td_pflags & TDP_ALTSTACK)
               ? ((oonstack) ? SS_ONSTACK : 0) : SS_DISABLE;
           sf.sf_uc.uc_mcontext.mc_onstack = (oonstack) ? 1 : 0;
           bcopy(regs, &sf.sf_uc.uc_mcontext.mc_rdi, sizeof(*regs));
           sf.sf_uc.uc_mcontext.mc_len = sizeof(sf.sf_uc.uc_mcontext); /* magic */
           get_fpcontext(td, &sf.sf_uc.uc_mcontext, xfpusave, xfpusave_len);
           fpstate_drop(td);
           update_pcb_bases(pcb);
           sf.sf_uc.uc_mcontext.mc_fsbase = pcb->pcb_fsbase;
           sf.sf_uc.uc_mcontext.mc_gsbase = pcb->pcb_gsbase;
           bzero(sf.sf_uc.uc_mcontext.mc_spare,
               sizeof(sf.sf_uc.uc_mcontext.mc_spare));
           bzero(sf.sf_uc.__spare__, sizeof(sf.sf_uc.__spare__));
   
           /* Allocate space for the signal handler context. */
           if ((td->td_pflags & TDP_ALTSTACK) != 0 && !oonstack &&
               SIGISMEMBER(psp->ps_sigonstack, sig)) {
                   sp = (char *)td->td_sigstk.ss_sp + td->td_sigstk.ss_size;
   #if defined(COMPAT_43)
                   td->td_sigstk.ss_flags |= SS_ONSTACK;
   #endif
           } else
                   sp = (char *)regs->tf_rsp - 128;
           if (xfpusave != NULL) {
                   sp -= xfpusave_len;
                   sp = (char *)((unsigned long)sp & ~0x3Ful);
                   sf.sf_uc.uc_mcontext.mc_xfpustate = (register_t)sp;
           }
           sp -= sizeof(struct sigframe);
           /* Align to 16 bytes. */
           sfp = (struct sigframe *)((unsigned long)sp & ~0xFul);
   
           /* Build the argument list for the signal handler. */
           regs->tf_rdi = sig;                     /* arg 1 in %rdi */
           regs->tf_rdx = (register_t)&sfp->sf_uc; /* arg 3 in %rdx */
           bzero(&sf.sf_si, sizeof(sf.sf_si));
           if (SIGISMEMBER(psp->ps_siginfo, sig)) {
                   /* Signal handler installed with SA_SIGINFO. */
                   regs->tf_rsi = (register_t)&sfp->sf_si; /* arg 2 in %rsi */
                   sf.sf_ahu.sf_action = (__siginfohandler_t *)catcher;
   
                   /* Fill in POSIX parts */
                   sf.sf_si = ksi->ksi_info;
                   sf.sf_si.si_signo = sig; /* maybe a translated signal */
                   regs->tf_rcx = (register_t)ksi->ksi_addr; /* arg 4 in %rcx */
           } else {
                   /* Old FreeBSD-style arguments. */
                   regs->tf_rsi = ksi->ksi_code;   /* arg 2 in %rsi */
                   regs->tf_rcx = (register_t)ksi->ksi_addr; /* arg 4 in %rcx */
                   sf.sf_ahu.sf_handler = catcher;
           }
           mtx_unlock(&psp->ps_mtx);
           PROC_UNLOCK(p);
   
           /*
            * Copy the sigframe out to the user's stack.
            */
           if (copyout(&sf, sfp, sizeof(*sfp)) != 0 ||
               (xfpusave != NULL && copyout(xfpusave,
               (void *)sf.sf_uc.uc_mcontext.mc_xfpustate, xfpusave_len)
               != 0)) {
   #ifdef DEBUG
                   printf("process %ld has trashed its stack\n", (long)p->p_pid);
   #endif
                   PROC_LOCK(p);
                   sigexit(td, SIGILL);
           }
   
           regs->tf_rsp = (long)sfp;
           regs->tf_rip = p->p_sysent->sv_sigcode_base;
           regs->tf_rflags &= ~(PSL_T | PSL_D);
           regs->tf_cs = _ucodesel;
           regs->tf_ds = _udatasel;
           regs->tf_ss = _udatasel;
           regs->tf_es = _udatasel;
           regs->tf_fs = _ufssel;
           regs->tf_gs = _ugssel;
           regs->tf_flags = TF_HASSEGS;
           PROC_LOCK(p);
           mtx_lock(&psp->ps_mtx);
   }
   
   /*
    * System call to cleanup state after a signal
    * has been taken.  Reset signal mask and
    * stack state from context left by sendsig (above).
    * Return to previous pc and psl as specified by
    * context left by sendsig. Check carefully to
    * make sure that the user has not modified the
    * state to gain improper privileges.
    *
    * MPSAFE
    */
   int
   sys_sigreturn(td, uap)
           struct thread *td;
           struct sigreturn_args /* {
                   const struct __ucontext *sigcntxp;
           } */ *uap;
   {
           ucontext_t uc;
           struct pcb *pcb;
           struct proc *p;
           struct trapframe *regs;
           ucontext_t *ucp;
           char *xfpustate;
           size_t xfpustate_len;
           long rflags;
           int cs, error, ret;
           ksiginfo_t ksi;
   
           pcb = td->td_pcb;
           p = td->td_proc;
   
           error = copyin(uap->sigcntxp, &uc, sizeof(uc));
           if (error != 0) {
                   uprintf("pid %d (%s): sigreturn copyin failed\n",
                       p->p_pid, td->td_name);
                   return (error);
           }
           ucp = &uc;
           if ((ucp->uc_mcontext.mc_flags & ~_MC_FLAG_MASK) != 0) {
                   uprintf("pid %d (%s): sigreturn mc_flags %x\n", p->p_pid,
                       td->td_name, ucp->uc_mcontext.mc_flags);
                   return (EINVAL);
           }
           regs = td->td_frame;
           rflags = ucp->uc_mcontext.mc_rflags;
           /*
            * Don't allow users to change privileged or reserved flags.
            */
           if (!EFL_SECURE(rflags, regs->tf_rflags)) {
                   uprintf("pid %d (%s): sigreturn rflags = 0x%lx\n", p->p_pid,
                       td->td_name, rflags);
                   return (EINVAL);
           }
   
           /*
            * Don't allow users to load a valid privileged %cs.  Let the
            * hardware check for invalid selectors, excess privilege in
            * other selectors, invalid %eip's and invalid %esp's.
            */
           cs = ucp->uc_mcontext.mc_cs;
           if (!CS_SECURE(cs)) {
                   uprintf("pid %d (%s): sigreturn cs = 0x%x\n", p->p_pid,
                       td->td_name, cs);
                   ksiginfo_init_trap(&ksi);
                   ksi.ksi_signo = SIGBUS;
                   ksi.ksi_code = BUS_OBJERR;
                   ksi.ksi_trapno = T_PROTFLT;
                   ksi.ksi_addr = (void *)regs->tf_rip;
                   trapsignal(td, &ksi);
                   return (EINVAL);
           }
   
           if ((uc.uc_mcontext.mc_flags & _MC_HASFPXSTATE) != 0) {
                   xfpustate_len = uc.uc_mcontext.mc_xfpustate_len;
                   if (xfpustate_len > cpu_max_ext_state_size -
                       sizeof(struct savefpu)) {
                           uprintf("pid %d (%s): sigreturn xfpusave_len = 0x%zx\n",
                               p->p_pid, td->td_name, xfpustate_len);
                           return (EINVAL);
                   }
                   xfpustate = __builtin_alloca(xfpustate_len);
                   error = copyin((const void *)uc.uc_mcontext.mc_xfpustate,
                       xfpustate, xfpustate_len);
                   if (error != 0) {
                           uprintf(
           "pid %d (%s): sigreturn copying xfpustate failed\n",
                               p->p_pid, td->td_name);
                           return (error);
                   }
           } else {
                   xfpustate = NULL;
                   xfpustate_len = 0;
           }
           ret = set_fpcontext(td, &ucp->uc_mcontext, xfpustate, xfpustate_len);
           if (ret != 0) {
                   uprintf("pid %d (%s): sigreturn set_fpcontext err %d\n",
                       p->p_pid, td->td_name, ret);
                   return (ret);
           }
           bcopy(&ucp->uc_mcontext.mc_rdi, regs, sizeof(*regs));
           update_pcb_bases(pcb);
           pcb->pcb_fsbase = ucp->uc_mcontext.mc_fsbase;
           pcb->pcb_gsbase = ucp->uc_mcontext.mc_gsbase;
   
   #if defined(COMPAT_43)
           if (ucp->uc_mcontext.mc_onstack & 1)
                   td->td_sigstk.ss_flags |= SS_ONSTACK;
           else
                   td->td_sigstk.ss_flags &= ~SS_ONSTACK;
   #endif
   
           kern_sigprocmask(td, SIG_SETMASK, &ucp->uc_sigmask, NULL, 0);
           return (EJUSTRETURN);
   }
   
   #ifdef COMPAT_FREEBSD4
   int
   freebsd4_sigreturn(struct thread *td, struct freebsd4_sigreturn_args *uap)
   {
    
           return sys_sigreturn(td, (struct sigreturn_args *)uap);
   }
   #endif
   
   /*
    * Reset registers to default values on exec.
    */
   void
   exec_setregs(struct thread *td, struct image_params *imgp, u_long stack)
   {
           struct trapframe *regs;
           struct pcb *pcb;
           register_t saved_rflags;
   
           regs = td->td_frame;
           pcb = td->td_pcb;
   
           mtx_lock(&dt_lock);
           if (td->td_proc->p_md.md_ldt != NULL)
                   user_ldt_free(td);
           else
                   mtx_unlock(&dt_lock);
           
           update_pcb_bases(pcb);
           pcb->pcb_fsbase = 0;
           pcb->pcb_gsbase = 0;
           clear_pcb_flags(pcb, PCB_32BIT);
           pcb->pcb_initial_fpucw = __INITIAL_FPUCW__;
   
           saved_rflags = regs->tf_rflags & PSL_T;
           bzero((char *)regs, sizeof(struct trapframe));
           regs->tf_rip = imgp->entry_addr;
           regs->tf_rsp = ((stack - 8) & ~0xFul) + 8;
           regs->tf_rdi = stack;           /* argv */
           regs->tf_rflags = PSL_USER | saved_rflags;
           regs->tf_ss = _udatasel;
           regs->tf_cs = _ucodesel;
           regs->tf_ds = _udatasel;
           regs->tf_es = _udatasel;
           regs->tf_fs = _ufssel;
           regs->tf_gs = _ugssel;
           regs->tf_flags = TF_HASSEGS;
           td->td_retval[1] = 0;
   
           /*
            * Reset the hardware debug registers if they were in use.
            * They won't have any meaning for the newly exec'd process.
            */
           if (pcb->pcb_flags & PCB_DBREGS) {
                   pcb->pcb_dr0 = 0;
                   pcb->pcb_dr1 = 0;
                   pcb->pcb_dr2 = 0;
                   pcb->pcb_dr3 = 0;
                   pcb->pcb_dr6 = 0;
                   pcb->pcb_dr7 = 0;
                   if (pcb == curpcb) {
                           /*
                            * Clear the debug registers on the running
                            * CPU, otherwise they will end up affecting
                            * the next process we switch to.
                            */
                           reset_dbregs();
                   }
                   clear_pcb_flags(pcb, PCB_DBREGS);
           }
   
           /*
            * Drop the FP state if we hold it, so that the process gets a
            * clean FP state if it uses the FPU again.
            */
           fpstate_drop(td);
   }
   
   void
   cpu_setregs(void)
   {
           register_t cr0;
   
           cr0 = rcr0();
           /*
            * CR0_MP, CR0_NE and CR0_TS are also set by npx_probe() for the
            * BSP.  See the comments there about why we set them.
            */
           cr0 |= CR0_MP | CR0_NE | CR0_TS | CR0_WP | CR0_AM;
           load_cr0(cr0);
   }
   
   /*
    * Initialize amd64 and configure to run kernel
    */
   
   /*
    * Initialize segments & interrupt table
    */
   
   struct user_segment_descriptor gdt[NGDT * MAXCPU];/* global descriptor tables */
   static struct gate_descriptor idt0[NIDT];
   struct gate_descriptor *idt = &idt0[0]; /* interrupt descriptor table */
   
   static char dblfault_stack[PAGE_SIZE] __aligned(16);
   static char mce0_stack[PAGE_SIZE] __aligned(16);
   static char nmi0_stack[PAGE_SIZE] __aligned(16);
   static char dbg0_stack[PAGE_SIZE] __aligned(16);
   CTASSERT(sizeof(struct nmi_pcpu) == 16);
   
   struct amd64tss common_tss[MAXCPU];
   
   /*
    * Software prototypes -- in more palatable form.
    *
    * Keep GUFS32, GUGS32, GUCODE32 and GUDATA at the same
    * slots as corresponding segments for i386 kernel.
    */
   struct soft_segment_descriptor gdt_segs[] = {
   /* GNULL_SEL    0 Null Descriptor */
   {       .ssd_base = 0x0,
           .ssd_limit = 0x0,
           .ssd_type = 0,
           .ssd_dpl = 0,
           .ssd_p = 0,
           .ssd_long = 0,
           .ssd_def32 = 0,
           .ssd_gran = 0           },
   /* GNULL2_SEL   1 Null Descriptor */
   {       .ssd_base = 0x0,
           .ssd_limit = 0x0,
           .ssd_type = 0,
           .ssd_dpl = 0,
           .ssd_p = 0,
           .ssd_long = 0,
           .ssd_def32 = 0,
           .ssd_gran = 0           },
   /* GUFS32_SEL   2 32 bit %gs Descriptor for user */
   {       .ssd_base = 0x0,
           .ssd_limit = 0xfffff,
           .ssd_type = SDT_MEMRWA,
           .ssd_dpl = SEL_UPL,
           .ssd_p = 1,
           .ssd_long = 0,
           .ssd_def32 = 1,
           .ssd_gran = 1           },
   /* GUGS32_SEL   3 32 bit %fs Descriptor for user */
   {       .ssd_base = 0x0,
           .ssd_limit = 0xfffff,
           .ssd_type = SDT_MEMRWA,
           .ssd_dpl = SEL_UPL,
           .ssd_p = 1,
           .ssd_long = 0,
           .ssd_def32 = 1,
           .ssd_gran = 1           },
   /* GCODE_SEL    4 Code Descriptor for kernel */
   {       .ssd_base = 0x0,
           .ssd_limit = 0xfffff,
           .ssd_type = SDT_MEMERA,
           .ssd_dpl = SEL_KPL,
           .ssd_p = 1,
           .ssd_long = 1,
           .ssd_def32 = 0,
           .ssd_gran = 1           },
   /* GDATA_SEL    5 Data Descriptor for kernel */
   {       .ssd_base = 0x0,
           .ssd_limit = 0xfffff,
           .ssd_type = SDT_MEMRWA,
           .ssd_dpl = SEL_KPL,
           .ssd_p = 1,
           .ssd_long = 1,
           .ssd_def32 = 0,
           .ssd_gran = 1           },
   /* GUCODE32_SEL 6 32 bit Code Descriptor for user */
   {       .ssd_base = 0x0,
           .ssd_limit = 0xfffff,
           .ssd_type = SDT_MEMERA,
           .ssd_dpl = SEL_UPL,
           .ssd_p = 1,
           .ssd_long = 0,
           .ssd_def32 = 1,
           .ssd_gran = 1           },
   /* GUDATA_SEL   7 32/64 bit Data Descriptor for user */
   {       .ssd_base = 0x0,
           .ssd_limit = 0xfffff,
           .ssd_type = SDT_MEMRWA,
           .ssd_dpl = SEL_UPL,
           .ssd_p = 1,
           .ssd_long = 0,
           .ssd_def32 = 1,
           .ssd_gran = 1           },
   /* GUCODE_SEL   8 64 bit Code Descriptor for user */
   {       .ssd_base = 0x0,
           .ssd_limit = 0xfffff,
           .ssd_type = SDT_MEMERA,
           .ssd_dpl = SEL_UPL,
           .ssd_p = 1,
           .ssd_long = 1,
           .ssd_def32 = 0,
           .ssd_gran = 1           },
   /* GPROC0_SEL   9 Proc 0 Tss Descriptor */
   {       .ssd_base = 0x0,
           .ssd_limit = sizeof(struct amd64tss) + IOPERM_BITMAP_SIZE - 1,
           .ssd_type = SDT_SYSTSS,
           .ssd_dpl = SEL_KPL,
           .ssd_p = 1,
           .ssd_long = 0,
           .ssd_def32 = 0,
           .ssd_gran = 0           },
   /* Actually, the TSS is a system descriptor which is double size */
   {       .ssd_base = 0x0,
           .ssd_limit = 0x0,
           .ssd_type = 0,
           .ssd_dpl = 0,
           .ssd_p = 0,
           .ssd_long = 0,
           .ssd_def32 = 0,
           .ssd_gran = 0           },
   /* GUSERLDT_SEL 11 LDT Descriptor */
   {       .ssd_base = 0x0,
           .ssd_limit = 0x0,
           .ssd_type = 0,
           .ssd_dpl = 0,
           .ssd_p = 0,
           .ssd_long = 0,
           .ssd_def32 = 0,
           .ssd_gran = 0           },
   /* GUSERLDT_SEL 12 LDT Descriptor, double size */
   {       .ssd_base = 0x0,
           .ssd_limit = 0x0,
           .ssd_type = 0,
           .ssd_dpl = 0,
           .ssd_p = 0,
           .ssd_long = 0,
           .ssd_def32 = 0,
           .ssd_gran = 0           },
   };
   
   void
   setidt(int idx, inthand_t *func, int typ, int dpl, int ist)
   {
           struct gate_descriptor *ip;
   
           ip = idt + idx;
           ip->gd_looffset = (uintptr_t)func;
           ip->gd_selector = GSEL(GCODE_SEL, SEL_KPL);
           ip->gd_ist = ist;
           ip->gd_xx = 0;
           ip->gd_type = typ;
           ip->gd_dpl = dpl;
           ip->gd_p = 1;
           ip->gd_hioffset = ((uintptr_t)func)>>16 ;
   }
   
   extern inthand_t
           IDTVEC(div), IDTVEC(dbg), IDTVEC(nmi), IDTVEC(bpt), IDTVEC(ofl),
           IDTVEC(bnd), IDTVEC(ill), IDTVEC(dna), IDTVEC(fpusegm),
           IDTVEC(tss), IDTVEC(missing), IDTVEC(stk), IDTVEC(prot),
           IDTVEC(page), IDTVEC(mchk), IDTVEC(rsvd), IDTVEC(fpu), IDTVEC(align),
           IDTVEC(xmm), IDTVEC(dblfault),
           IDTVEC(div_pti), IDTVEC(bpt_pti),
           IDTVEC(ofl_pti), IDTVEC(bnd_pti), IDTVEC(ill_pti), IDTVEC(dna_pti),
           IDTVEC(fpusegm_pti), IDTVEC(tss_pti), IDTVEC(missing_pti),
           IDTVEC(stk_pti), IDTVEC(prot_pti), IDTVEC(page_pti),
           IDTVEC(rsvd_pti), IDTVEC(fpu_pti), IDTVEC(align_pti),
           IDTVEC(xmm_pti),
   #ifdef KDTRACE_HOOKS
           IDTVEC(dtrace_ret), IDTVEC(dtrace_ret_pti),
   #endif
   #ifdef XENHVM
           IDTVEC(xen_intr_upcall), IDTVEC(xen_intr_upcall_pti),
   #endif
           IDTVEC(fast_syscall), IDTVEC(fast_syscall32),
           IDTVEC(fast_syscall_pti);
   
   #ifdef DDB
   /*
    * Display the index and function name of any IDT entries that don't use
    * the default 'rsvd' entry point.
    */
   DB_SHOW_COMMAND(idt, db_show_idt)
   {
           struct gate_descriptor *ip;
           int idx;
           uintptr_t func;
   
           ip = idt;
           for (idx = 0; idx < NIDT && !db_pager_quit; idx++) {
                   func = ((long)ip->gd_hioffset << 16 | ip->gd_looffset);
                   if (func != (uintptr_t)&IDTVEC(rsvd)) {
                           db_printf("%3d\t", idx);
                           db_printsym(func, DB_STGY_PROC);
                           db_printf("\n");
                   }
                   ip++;
           }
   }
   
   /* Show privileged registers. */
   DB_SHOW_COMMAND(sysregs, db_show_sysregs)
   {
           struct {
                   uint16_t limit;
                   uint64_t base;
           } __packed idtr, gdtr;
           uint16_t ldt, tr;
   
           __asm __volatile("sidt %0" : "=m" (idtr));
           db_printf("idtr\t0x%016lx/%04x\n",
               (u_long)idtr.base, (u_int)idtr.limit);
           __asm __volatile("sgdt %0" : "=m" (gdtr));
           db_printf("gdtr\t0x%016lx/%04x\n",
               (u_long)gdtr.base, (u_int)gdtr.limit);
           __asm __volatile("sldt %0" : "=r" (ldt));
           db_printf("ldtr\t0x%04x\n", ldt);
           __asm __volatile("str %0" : "=r" (tr));
           db_printf("tr\t0x%04x\n", tr);
           db_printf("cr0\t0x%016lx\n", rcr0());
           db_printf("cr2\t0x%016lx\n", rcr2());
           db_printf("cr3\t0x%016lx\n", rcr3());
           db_printf("cr4\t0x%016lx\n", rcr4());
           if (rcr4() & CR4_XSAVE)
                   db_printf("xcr0\t0x%016lx\n", rxcr(0));
           db_printf("EFER\t0x%016lx\n", rdmsr(MSR_EFER));
           if (cpu_feature2 & (CPUID2_VMX | CPUID2_SMX))
                   db_printf("FEATURES_CTL\t%016lx\n",
                       rdmsr(MSR_IA32_FEATURE_CONTROL));
           db_printf("DEBUG_CTL\t0x%016lx\n", rdmsr(MSR_DEBUGCTLMSR));
           db_printf("PAT\t0x%016lx\n", rdmsr(MSR_PAT));
           db_printf("GSBASE\t0x%016lx\n", rdmsr(MSR_GSBASE));
   }
   
   DB_SHOW_COMMAND(dbregs, db_show_dbregs)
   {
   
           db_printf("dr0\t0x%016lx\n", rdr0());
           db_printf("dr1\t0x%016lx\n", rdr1());
           db_printf("dr2\t0x%016lx\n", rdr2());
           db_printf("dr3\t0x%016lx\n", rdr3());
           db_printf("dr6\t0x%016lx\n", rdr6());
           db_printf("dr7\t0x%016lx\n", rdr7());   
   }
   #endif
   
   void
   sdtossd(sd, ssd)
           struct user_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_long  = sd->sd_long;
           ssd->ssd_def32 = sd->sd_def32;
           ssd->ssd_gran  = sd->sd_gran;
   }
   
   void
   ssdtosd(ssd, sd)
           struct soft_segment_descriptor *ssd;
           struct user_segment_descriptor *sd;
   {
   
           sd->sd_lobase = (ssd->ssd_base) & 0xffffff;
           sd->sd_hibase = (ssd->ssd_base >> 24) & 0xff;
           sd->sd_lolimit = (ssd->ssd_limit) & 0xffff;
           sd->sd_hilimit = (ssd->ssd_limit >> 16) & 0xf;
           sd->sd_type  = ssd->ssd_type;
           sd->sd_dpl   = ssd->ssd_dpl;
           sd->sd_p     = ssd->ssd_p;
           sd->sd_long  = ssd->ssd_long;
           sd->sd_def32 = ssd->ssd_def32;
           sd->sd_gran  = ssd->ssd_gran;
   }
   
   void
   ssdtosyssd(ssd, sd)
           struct soft_segment_descriptor *ssd;
           struct system_segment_descriptor *sd;
   {
   
           sd->sd_lobase = (ssd->ssd_base) & 0xffffff;
           sd->sd_hibase = (ssd->ssd_base >> 24) & 0xfffffffffful;
           sd->sd_lolimit = (ssd->ssd_limit) & 0xffff;
           sd->sd_hilimit = (ssd->ssd_limit >> 16) & 0xf;
           sd->sd_type  = ssd->ssd_type;
           sd->sd_dpl   = ssd->ssd_dpl;
           sd->sd_p     = ssd->ssd_p;
           sd->sd_gran  = ssd->ssd_gran;
   }
   
   #if !defined(DEV_ATPIC) && defined(DEV_ISA)
   #include <isa/isavar.h>
   #include <isa/isareg.h>
   /*
    * Return a bitmap of the current interrupt requests.  This is 8259-specific
    * and is only suitable for use at probe time.
    * This is only here to pacify sio.  It is NOT FATAL if this doesn't work.
    * It shouldn't be here.  There should probably be an APIC centric
    * implementation in the apic driver code, if at all.
    */
   intrmask_t
   isa_irq_pending(void)
   {
           u_char irr1;
           u_char irr2;
   
           irr1 = inb(IO_ICU1);
           irr2 = inb(IO_ICU2);
           return ((irr2 << 8) | irr1);
   }
   #endif
   
   u_int basemem;
   
   static int
   add_physmap_entry(uint64_t base, uint64_t length, vm_paddr_t *physmap,
       int *physmap_idxp)
   {
          int i, insert_idx, physmap_idx;
  
          physmap_idx = *physmap_idxp;
  
          if (length == 0)
                  return (1);
  
          /*
           * Find insertion point while checking for overlap.  Start off by
           * assuming the new entry will be added to the end.
           *
           * NB: physmap_idx points to the next free slot.
           */
          insert_idx = physmap_idx;
          for (i = 0; i <= physmap_idx; i += 2) {
                  if (base < physmap[i + 1]) {
                          if (base + length <= physmap[i]) {
                                  insert_idx = i;
                                  break;
                          }
                          if (boothowto & RB_VERBOSE)
                                  printf(
                      "Overlapping memory regions, ignoring second region\n");
                          return (1);
                  }
          }
  
          /* See if we can prepend to the next entry. */
          if (insert_idx <= physmap_idx && base + length == physmap[insert_idx]) {
                  physmap[insert_idx] = base;
                  return (1);
          }
  
          /* See if we can append to the previous entry. */
          if (insert_idx > 0 && base == physmap[insert_idx - 1]) {
                  physmap[insert_idx - 1] += length;
                  return (1);
          }
  
          physmap_idx += 2;
          *physmap_idxp = physmap_idx;
          if (physmap_idx == PHYSMAP_SIZE) {
                  printf(
                  "Too many segments in the physical address map, giving up\n");
                  return (0);
          }
  
          /*
           * Move the last 'N' entries down to make room for the new
           * entry if needed.
           */
          for (i = (physmap_idx - 2); i > insert_idx; i -= 2) {
                  physmap[i] = physmap[i - 2];
                  physmap[i + 1] = physmap[i - 1];
          }
  
          /* Insert the new entry. */
          physmap[insert_idx] = base;
          physmap[insert_idx + 1] = base + length;
          return (1);
  }
  
  void
  bios_add_smap_entries(struct bios_smap *smapbase, u_int32_t smapsize,
                        vm_paddr_t *physmap, int *physmap_idx)
  {
          struct bios_smap *smap, *smapend;
  
          smapend = (struct bios_smap *)((uintptr_t)smapbase + smapsize);
  
          for (smap = smapbase; smap < smapend; smap++) {
                  if (boothowto & RB_VERBOSE)
                          printf("SMAP type=%02x base=%016lx len=%016lx\n",
                              smap->type, smap->base, smap->length);
  
                  if (smap->type != SMAP_TYPE_MEMORY)
                          continue;
  
                  if (!add_physmap_entry(smap->base, smap->length, physmap,
                      physmap_idx))
                          break;
          }
  }
  
  static void
  add_efi_map_entries(struct efi_map_header *efihdr, vm_paddr_t *physmap,
      int *physmap_idx)
  {
          struct efi_md *map, *p;
          const char *type;
          size_t efisz;
          int ndesc, i;
  
          static const char *types[] = {
                  "Reserved",
                  "LoaderCode",
                  "LoaderData",
                  "BootServicesCode",
                  "BootServicesData",
                  "RuntimeServicesCode",
                  "RuntimeServicesData",
                  "ConventionalMemory",
                  "UnusableMemory",
                  "ACPIReclaimMemory",
                  "ACPIMemoryNVS",
                  "MemoryMappedIO",
                  "MemoryMappedIOPortSpace",
                  "PalCode",
                  "PersistentMemory"
          };
  
          /*
           * Memory map data provided by UEFI via the GetMemoryMap
           * Boot Services API.
           */
          efisz = (sizeof(struct efi_map_header) + 0xf) & ~0xf;
          map = (struct efi_md *)((uint8_t *)efihdr + efisz);
  
          if (efihdr->descriptor_size == 0)
                  return;
          ndesc = efihdr->memory_size / efihdr->descriptor_size;
  
          if (boothowto & RB_VERBOSE)
                  printf("%23s %12s %12s %8s %4s\n",
                      "Type", "Physical", "Virtual", "#Pages", "Attr");
  
          for (i = 0, p = map; i < ndesc; i++,
              p = efi_next_descriptor(p, efihdr->descriptor_size)) {
                  if (boothowto & RB_VERBOSE) {
                          if (p->md_type < nitems(types))
                                  type = types[p->md_type];
                          else
                                  type = "<INVALID>";
                          printf("%23s %012lx %12p %08lx ", type, p->md_phys,
                              p->md_virt, p->md_pages);
                          if (p->md_attr & EFI_MD_ATTR_UC)
                                  printf("UC ");
                          if (p->md_attr & EFI_MD_ATTR_WC)
                                  printf("WC ");
                          if (p->md_attr & EFI_MD_ATTR_WT)
                                  printf("WT ");
                          if (p->md_attr & EFI_MD_ATTR_WB)
                                  printf("WB ");
                          if (p->md_attr & EFI_MD_ATTR_UCE)
                                  printf("UCE ");
                          if (p->md_attr & EFI_MD_ATTR_WP)
                                  printf("WP ");
                          if (p->md_attr & EFI_MD_ATTR_RP)
                                  printf("RP ");
                          if (p->md_attr & EFI_MD_ATTR_XP)
                                  printf("XP ");
                          if (p->md_attr & EFI_MD_ATTR_NV)
                                  printf("NV ");
                          if (p->md_attr & EFI_MD_ATTR_MORE_RELIABLE)
                                  printf("MORE_RELIABLE ");
                          if (p->md_attr & EFI_MD_ATTR_RO)
                                  printf("RO ");
                          if (p->md_attr & EFI_MD_ATTR_RT)
                                  printf("RUNTIME");
                          printf("\n");
                  }
  
                  switch (p->md_type) {
                  case EFI_MD_TYPE_CODE:
                  case EFI_MD_TYPE_DATA:
                  case EFI_MD_TYPE_BS_CODE:
                  case EFI_MD_TYPE_BS_DATA:
                  case EFI_MD_TYPE_FREE:
                          /*
                           * We're allowed to use any entry with these types.
                           */
                          break;
                  default:
                          continue;
                  }
  
                  if (!add_physmap_entry(p->md_phys, (p->md_pages * PAGE_SIZE),
                      physmap, physmap_idx))
                          break;
          }
  }
  
  static char bootmethod[16] = "";
  SYSCTL_STRING(_machdep, OID_AUTO, bootmethod, CTLFLAG_RD, bootmethod, 0,
      "System firmware boot method");
  
  static void
  native_parse_memmap(caddr_t kmdp, vm_paddr_t *physmap, int *physmap_idx)
  {
          struct bios_smap *smap;
          struct efi_map_header *efihdr;
          u_int32_t size;
  
          /*
           * Memory map from INT 15:E820.
           *
           * subr_module.c says:
           * "Consumer may safely assume that size value precedes data."
           * ie: an int32_t immediately precedes smap.
           */
  
          efihdr = (struct efi_map_header *)preload_search_info(kmdp,
              MODINFO_METADATA | MODINFOMD_EFI_MAP);
          smap = (struct bios_smap *)preload_search_info(kmdp,
              MODINFO_METADATA | MODINFOMD_SMAP);
          if (efihdr == NULL && smap == NULL)
                  panic("No BIOS smap or EFI map info from loader!");
  
          if (efihdr != NULL) {
                  add_efi_map_entries(efihdr, physmap, physmap_idx);
                  strlcpy(bootmethod, "UEFI", sizeof(bootmethod));
          } else {
                  size = *((u_int32_t *)smap - 1);
                  bios_add_smap_entries(smap, size, physmap, physmap_idx);
                  strlcpy(bootmethod, "BIOS", sizeof(bootmethod));
          }
  }
  
  #define PAGES_PER_GB    (1024 * 1024 * 1024 / PAGE_SIZE)
  
  /*
   * 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.
   *
   * Total memory size may be set by the kernel environment variable
   * hw.physmem or the compile-time define MAXMEM.
   *
   * XXX first should be vm_paddr_t.
   */
  static void
  getmemsize(caddr_t kmdp, u_int64_t first)
  {
          int i, physmap_idx, pa_indx, da_indx;
          vm_paddr_t pa, physmap[PHYSMAP_SIZE];
          u_long physmem_start, physmem_tunable, memtest;
          pt_entry_t *pte;
          quad_t dcons_addr, dcons_size;
          int page_counter;
  
          /*
           * Tell the physical memory allocator about pages used to store
           * the kernel and preloaded data.  See kmem_bootstrap_free().
           */
          vm_phys_add_seg((vm_paddr_t)kernphys, trunc_page(first));
  
          bzero(physmap, sizeof(physmap));
          physmap_idx = 0;
  
          init_ops.parse_memmap(kmdp, physmap, &physmap_idx);
          physmap_idx -= 2;
  
          /*
           * Find the 'base memory' segment for SMP
           */
          basemem = 0;
          for (i = 0; i <= physmap_idx; i += 2) {
                  if (physmap[i] <= 0xA0000) {
                          basemem = physmap[i + 1] / 1024;
                          break;
                  }
          }
          if (basemem == 0 || basemem > 640) {
                  if (bootverbose)
                          printf(
                  "Memory map doesn't contain a basemem segment, faking it");
                  basemem = 640;
          }
  
          /*
           * Make hole for "AP -> long mode" bootstrap code.  The
           * mp_bootaddress vector is only available when the kernel
           * is configured to support APs and APs for the system start
           * in 32bit mode (e.g. SMP bare metal).
           */
          if (init_ops.mp_bootaddress) {
                  if (physmap[1] >= 0x100000000)
                          panic(
          "Basemem segment is not suitable for AP bootstrap code!");
                  physmap[1] = init_ops.mp_bootaddress(physmap[1] / 1024);
          }
  
          /*
           * 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
  
          if (TUNABLE_ULONG_FETCH("hw.physmem", &physmem_tunable))
                  Maxmem = atop(physmem_tunable);
  
          /*
           * The boot memory test is disabled by default, as it takes a
           * significant amount of time on large-memory systems, and is
           * unfriendly to virtual machines as it unnecessarily touches all
           * pages.
           *
           * A general name is used as the code may be extended to support
           * additional tests beyond the current "page present" test.
           */
          memtest = 0;
          TUNABLE_ULONG_FETCH("hw.memtest.tests", &memtest);
  
          /*
           * Don't allow MAXMEM or hw.physmem to extend the amount of memory
           * in the system.
           */
          if (Maxmem > atop(physmap[physmap_idx + 1]))
                  Maxmem = atop(physmap[physmap_idx + 1]);
  
          if (atop(physmap[physmap_idx + 1]) != Maxmem &&
              (boothowto & RB_VERBOSE))
                  printf("Physical memory use set to %ldK\n", Maxmem * 4);
  
          /* call pmap initialization to make new kernel address space */
          pmap_bootstrap(&first);
  
          /*
           * Size up each available chunk of physical memory.
           *
           * XXX Some BIOSes corrupt low 64KB between suspend and resume.
           * By default, mask off the first 16 pages unless we appear to be
           * running in a VM.
           */
          physmem_start = (vm_guest > VM_GUEST_NO ? 1 : 16) << PAGE_SHIFT;
          TUNABLE_ULONG_FETCH("hw.physmem.start", &physmem_start);
          if (physmap[0] < physmem_start) {
                  if (physmem_start < PAGE_SIZE)
                          physmap[0] = PAGE_SIZE;
                  else if (physmem_start >= physmap[1])
                          physmap[0] = round_page(physmap[1] - PAGE_SIZE);
                  else
                          physmap[0] = round_page(physmem_start);
          }
          pa_indx = 0;
          da_indx = 1;
          phys_avail[pa_indx++] = physmap[0];
          phys_avail[pa_indx] = physmap[0];
          dump_avail[da_indx] = physmap[0];
          pte = CMAP1;
  
          /*
           * Get dcons buffer address
           */
          if (getenv_quad("dcons.addr", &dcons_addr) == 0 ||
              getenv_quad("dcons.size", &dcons_size) == 0)
                  dcons_addr = 0;
  
          /*
           * physmap is in bytes, so when converting to page boundaries,
           * round up the start address and round down the end address.
           */
          page_counter = 0;
          if (memtest != 0)
                  printf("Testing system memory");
          for (i = 0; i <= physmap_idx; i += 2) {
                  vm_paddr_t end;
  
                  end = ptoa((vm_paddr_t)Maxmem);
                  if (physmap[i + 1] < end)
                          end = trunc_page(physmap[i + 1]);
                  for (pa = round_page(physmap[i]); pa < end; pa += PAGE_SIZE) {
                          int tmp, page_bad, full;
                          int *ptr = (int *)CADDR1;
  
                          full = FALSE;
                          /*
                           * block out kernel memory as not available.
                           */
                          if (pa >= (vm_paddr_t)kernphys && pa < first)
                                  goto do_dump_avail;
  
                          /*
                           * block out dcons buffer
                           */
                          if (dcons_addr > 0
                              && pa >= trunc_page(dcons_addr)
                              && pa < dcons_addr + dcons_size)
                                  goto do_dump_avail;
  
                          page_bad = FALSE;
                          if (memtest == 0)
                                  goto skip_memtest;
  
                          /*
                           * Print a "." every GB to show we're making
                           * progress.
                           */
                          page_counter++;
                          if ((page_counter % PAGES_PER_GB) == 0)
                                  printf(".");
  
                          /*
                           * map page into kernel: valid, read/write,non-cacheable
                           */
                          *pte = pa | PG_V | PG_RW | PG_NC_PWT | PG_NC_PCD;
                          invltlb();
  
                          tmp = *(int *)ptr;
                          /*
                           * Test for alternating 1's and 0's
                           */
                          *(volatile int *)ptr = 0xaaaaaaaa;
                          if (*(volatile int *)ptr != 0xaaaaaaaa)
                                  page_bad = TRUE;
                          /*
                           * Test for alternating 0's and 1's
                           */
                          *(volatile int *)ptr = 0x55555555;
                          if (*(volatile int *)ptr != 0x55555555)
                                  page_bad = TRUE;
                          /*
                           * Test for all 1's
                           */
                          *(volatile int *)ptr = 0xffffffff;
                          if (*(volatile int *)ptr != 0xffffffff)
                                  page_bad = TRUE;
                          /*
                           * Test for all 0's
                           */
                          *(volatile int *)ptr = 0x0;
                          if (*(volatile int *)ptr != 0x0)
                                  page_bad = TRUE;
                          /*
                           * Restore original value.
                           */
                          *(int *)ptr = tmp;
  
  skip_memtest:
                          /*
                           * Adjust array of valid/good pages.
                           */
                          if (page_bad == TRUE)
                                  continue;
                          /*
                           * If this good page is a continuation of the
                           * previous set of good pages, then just increase
                           * the end pointer. Otherwise start a new chunk.
                           * Note that "end" points one higher than end,
                           * making the range >= start and < end.
                           * If we're also doing a speculative memory
                           * test and we at or past the end, bump up Maxmem
                           * so that we keep going. The first bad page
                           * will terminate the loop.
                           */
                          if (phys_avail[pa_indx] == pa) {
                                  phys_avail[pa_indx] += PAGE_SIZE;
                          } else {
                                  pa_indx++;
                                  if (pa_indx == PHYS_AVAIL_ARRAY_END) {
                                          printf(
                  "Too many holes in the physical address space, giving up\n");
                                          pa_indx--;
                                          full = TRUE;
                                          goto do_dump_avail;
                                  }
                                  phys_avail[pa_indx++] = pa;     /* start */
                                  phys_avail[pa_indx] = pa + PAGE_SIZE; /* end */
                          }
                          physmem++;
  do_dump_avail:
                          if (dump_avail[da_indx] == pa) {
                                  dump_avail[da_indx] += PAGE_SIZE;
                          } else {
                                  da_indx++;
                                  if (da_indx == DUMP_AVAIL_ARRAY_END) {
                                          da_indx--;
                                          goto do_next;
                                  }
                                  dump_avail[da_indx++] = pa; /* start */
                                  dump_avail[da_indx] = pa + PAGE_SIZE; /* end */
                          }
  do_next:
                          if (full)
                                  break;
                  }
          }
          *pte = 0;
          invltlb();
          if (memtest != 0)
                  printf("\n");
  
          /*
           * XXX
           * The last chunk must contain at least one page plus the message
           * buffer to avoid complicating other code (message buffer address
           * calculation, etc.).
           */
          while (phys_avail[pa_indx - 1] + PAGE_SIZE +
              round_page(msgbufsize) >= phys_avail[pa_indx]) {
                  physmem -= atop(phys_avail[pa_indx] - phys_avail[pa_indx - 1]);
                  phys_avail[pa_indx--] = 0;
                  phys_avail[pa_indx--] = 0;
          }
  
          Maxmem = atop(phys_avail[pa_indx]);
  
          /* Trim off space for the message buffer. */
          phys_avail[pa_indx] -= round_page(msgbufsize);
  
          /* Map the message buffer. */
          msgbufp = (struct msgbuf *)PHYS_TO_DMAP(phys_avail[pa_indx]);
  }
  
  static caddr_t
  native_parse_preload_data(u_int64_t modulep)
  {
          caddr_t kmdp;
          char *envp;
  #ifdef DDB
          vm_offset_t ksym_start;
          vm_offset_t ksym_end;
  #endif
  
          preload_metadata = (caddr_t)(uintptr_t)(modulep + KERNBASE);
          preload_bootstrap_relocate(KERNBASE);
          kmdp = preload_search_by_type("elf kernel");
          if (kmdp == NULL)
                  kmdp = preload_search_by_type("elf64 kernel");
          boothowto = MD_FETCH(kmdp, MODINFOMD_HOWTO, int);
          envp = MD_FETCH(kmdp, MODINFOMD_ENVP, char *);
          if (envp != NULL)
                  envp += KERNBASE;
          init_static_kenv(envp, 0);
  #ifdef DDB
          ksym_start = MD_FETCH(kmdp, MODINFOMD_SSYM, uintptr_t);
          ksym_end = MD_FETCH(kmdp, MODINFOMD_ESYM, uintptr_t);
          db_fetch_ksymtab(ksym_start, ksym_end);
  #endif
          efi_systbl_phys = MD_FETCH(kmdp, MODINFOMD_FW_HANDLE, vm_paddr_t);
  
          return (kmdp);
  }
  
  static void
  amd64_kdb_init(void)
  {
          kdb_init();
  #ifdef KDB
          if (boothowto & RB_KDB)
                  kdb_enter(KDB_WHY_BOOTFLAGS, "Boot flags requested debugger");
  #endif
  }
  
  /* Set up the fast syscall stuff */
  void
  amd64_conf_fast_syscall(void)
  {
          uint64_t msr;
  
          msr = rdmsr(MSR_EFER) | EFER_SCE;
          wrmsr(MSR_EFER, msr);
          wrmsr(MSR_LSTAR, pti ? (u_int64_t)IDTVEC(fast_syscall_pti) :
              (u_int64_t)IDTVEC(fast_syscall));
          wrmsr(MSR_CSTAR, (u_int64_t)IDTVEC(fast_syscall32));
          msr = ((u_int64_t)GSEL(GCODE_SEL, SEL_KPL) << 32) |
              ((u_int64_t)GSEL(GUCODE32_SEL, SEL_UPL) << 48);
          wrmsr(MSR_STAR, msr);
          wrmsr(MSR_SF_MASK, PSL_NT | PSL_T | PSL_I | PSL_C | PSL_D);
  }
  
  u_int64_t
  hammer_time(u_int64_t modulep, u_int64_t physfree)
  {
          caddr_t kmdp;
          int gsel_tss, x;
          struct pcpu *pc;
          struct nmi_pcpu *np;
          struct xstate_hdr *xhdr;
          u_int64_t rsp0;
          char *env;
          size_t kstack0_sz;
          int late_console;
  
          kmdp = init_ops.parse_preload_data(modulep);
  
          physfree += ucode_load_bsp(physfree + KERNBASE);
          physfree = roundup2(physfree, PAGE_SIZE);
  
          identify_cpu1();
          identify_hypervisor();
          /*
           * hw.cpu_stdext_disable is ignored by the call, it will be
           * re-evaluted by the below call to finishidentcpu().
           */
          identify_cpu2();
  
          link_elf_ireloc(kmdp);
  
          /*
           * This may be done better later if it gets more high level
           * components in it. If so just link td->td_proc here.
           */
          proc_linkup0(&proc0, &thread0);
  
          /* Init basic tunables, hz etc */
          init_param1();
  
          thread0.td_kstack = physfree + KERNBASE;
          thread0.td_kstack_pages = kstack_pages;
          kstack0_sz = thread0.td_kstack_pages * PAGE_SIZE;
          bzero((void *)thread0.td_kstack, kstack0_sz);
          physfree += kstack0_sz;
  
          /*
           * make gdt memory segments
           */
          for (x = 0; x < NGDT; x++) {
                  if (x != GPROC0_SEL && x != (GPROC0_SEL + 1) &&
                      x != GUSERLDT_SEL && x != (GUSERLDT_SEL) + 1)
                          ssdtosd(&gdt_segs[x], &gdt[x]);
          }
          gdt_segs[GPROC0_SEL].ssd_base = (uintptr_t)&common_tss[0];
          ssdtosyssd(&gdt_segs[GPROC0_SEL],
              (struct system_segment_descriptor *)&gdt[GPROC0_SEL]);
  
          r_gdt.rd_limit = NGDT * sizeof(gdt[0]) - 1;
          r_gdt.rd_base =  (long) gdt;
          lgdt(&r_gdt);
          pc = &__pcpu[0];
  
          wrmsr(MSR_FSBASE, 0);           /* User value */
          wrmsr(MSR_GSBASE, (u_int64_t)pc);
          wrmsr(MSR_KGSBASE, 0);          /* User value while in the kernel */
  
          pcpu_init(pc, 0, sizeof(struct pcpu));
          dpcpu_init((void *)(physfree + KERNBASE), 0);
          physfree += DPCPU_SIZE;
          PCPU_SET(prvspace, pc);
          PCPU_SET(curthread, &thread0);
          /* Non-late cninit() and printf() can be moved up to here. */
          PCPU_SET(tssp, &common_tss[0]);
          PCPU_SET(commontssp, &common_tss[0]);
          PCPU_SET(tss, (struct system_segment_descriptor *)&gdt[GPROC0_SEL]);
          PCPU_SET(ldt, (struct system_segment_descriptor *)&gdt[GUSERLDT_SEL]);
          PCPU_SET(fs32p, &gdt[GUFS32_SEL]);
          PCPU_SET(gs32p, &gdt[GUGS32_SEL]);
  
          /*
           * Initialize mutexes.
           *
           * icu_lock: in order to allow an interrupt to occur in a critical
           *           section, to set pcpu->ipending (etc...) properly, we
           *           must be able to get the icu lock, so it can't be
           *           under witness.
           */
          mutex_init();
          mtx_init(&icu_lock, "icu", NULL, MTX_SPIN | MTX_NOWITNESS);
          mtx_init(&dt_lock, "descriptor tables", NULL, MTX_DEF);
  
          /* exceptions */
          pti = pti_get_default();
          TUNABLE_INT_FETCH("vm.pmap.pti", &pti);
  
          for (x = 0; x < NIDT; x++)
                  setidt(x, pti ? &IDTVEC(rsvd_pti) : &IDTVEC(rsvd), SDT_SYSIGT,
                      SEL_KPL, 0);
          setidt(IDT_DE, pti ? &IDTVEC(div_pti) : &IDTVEC(div), SDT_SYSIGT,
              SEL_KPL, 0);
          setidt(IDT_DB, &IDTVEC(dbg), SDT_SYSIGT, SEL_KPL, 4);
          setidt(IDT_NMI, &IDTVEC(nmi),  SDT_SYSIGT, SEL_KPL, 2);
          setidt(IDT_BP, pti ? &IDTVEC(bpt_pti) : &IDTVEC(bpt), SDT_SYSIGT,
              SEL_UPL, 0);
          setidt(IDT_OF, pti ? &IDTVEC(ofl_pti) : &IDTVEC(ofl), SDT_SYSIGT,
              SEL_UPL, 0);
          setidt(IDT_BR, pti ? &IDTVEC(bnd_pti) : &IDTVEC(bnd), SDT_SYSIGT,
              SEL_KPL, 0);
          setidt(IDT_UD, pti ? &IDTVEC(ill_pti) : &IDTVEC(ill), SDT_SYSIGT,
              SEL_KPL, 0);
          setidt(IDT_NM, pti ? &IDTVEC(dna_pti) : &IDTVEC(dna), SDT_SYSIGT,
              SEL_KPL, 0);
          setidt(IDT_DF, &IDTVEC(dblfault), SDT_SYSIGT, SEL_KPL, 1);
          setidt(IDT_FPUGP, pti ? &IDTVEC(fpusegm_pti) : &IDTVEC(fpusegm),
              SDT_SYSIGT, SEL_KPL, 0);
          setidt(IDT_TS, pti ? &IDTVEC(tss_pti) : &IDTVEC(tss), SDT_SYSIGT,
              SEL_KPL, 0);
          setidt(IDT_NP, pti ? &IDTVEC(missing_pti) : &IDTVEC(missing),
              SDT_SYSIGT, SEL_KPL, 0);
          setidt(IDT_SS, pti ? &IDTVEC(stk_pti) : &IDTVEC(stk), SDT_SYSIGT,
              SEL_KPL, 0);
          setidt(IDT_GP, pti ? &IDTVEC(prot_pti) : &IDTVEC(prot), SDT_SYSIGT,
              SEL_KPL, 0);
          setidt(IDT_PF, pti ? &IDTVEC(page_pti) : &IDTVEC(page), SDT_SYSIGT,
              SEL_KPL, 0);
          setidt(IDT_MF, pti ? &IDTVEC(fpu_pti) : &IDTVEC(fpu), SDT_SYSIGT,
              SEL_KPL, 0);
          setidt(IDT_AC, pti ? &IDTVEC(align_pti) : &IDTVEC(align), SDT_SYSIGT,
              SEL_KPL, 0);
          setidt(IDT_MC, &IDTVEC(mchk), SDT_SYSIGT, SEL_KPL, 3);
          setidt(IDT_XF, pti ? &IDTVEC(xmm_pti) : &IDTVEC(xmm), SDT_SYSIGT,
              SEL_KPL, 0);
  #ifdef KDTRACE_HOOKS
          setidt(IDT_DTRACE_RET, pti ? &IDTVEC(dtrace_ret_pti) :
              &IDTVEC(dtrace_ret), SDT_SYSIGT, SEL_UPL, 0);
  #endif
  #ifdef XENHVM
          setidt(IDT_EVTCHN, pti ? &IDTVEC(xen_intr_upcall_pti) :
              &IDTVEC(xen_intr_upcall), SDT_SYSIGT, SEL_KPL, 0);
  #endif
          r_idt.rd_limit = sizeof(idt0) - 1;
          r_idt.rd_base = (long) idt;
          lidt(&r_idt);
  
          /*
           * Initialize the clock before the console so that console
           * initialization can use DELAY().
           */
          clock_init();
  
          /*
           * Use vt(4) by default for UEFI boot (during the sc(4)/vt(4)
           * transition).
           * Once bootblocks have updated, we can test directly for
           * efi_systbl != NULL here...
           */
          if (preload_search_info(kmdp, MODINFO_METADATA | MODINFOMD_EFI_MAP)
              != NULL)
                  vty_set_preferred(VTY_VT);
  
          TUNABLE_INT_FETCH("hw.ibrs_disable", &hw_ibrs_disable);
          TUNABLE_INT_FETCH("hw.spec_store_bypass_disable", &hw_ssb_disable);
          TUNABLE_INT_FETCH("hw.mds_disable", &hw_mds_disable);
          TUNABLE_INT_FETCH("machdep.mitigations.taa.enable", &x86_taa_enable);
  
          TUNABLE_INT_FETCH("machdep.mitigations.rndgs.enable",
              &x86_rngds_mitg_enable);
  
          finishidentcpu();       /* Final stage of CPU initialization */
          initializecpu();        /* Initialize CPU registers */
          initializecpucache();
  
          /* doublefault stack space, runs on ist1 */
          common_tss[0].tss_ist1 = (long)&dblfault_stack[sizeof(dblfault_stack)];
  
          /*
           * NMI stack, runs on ist2.  The pcpu pointer is stored just
           * above the start of the ist2 stack.
           */
          np = ((struct nmi_pcpu *) &nmi0_stack[sizeof(nmi0_stack)]) - 1;
          np->np_pcpu = (register_t) pc;
          common_tss[0].tss_ist2 = (long) np;
  
          /*
           * MC# stack, runs on ist3.  The pcpu pointer is stored just
           * above the start of the ist3 stack.
           */
          np = ((struct nmi_pcpu *) &mce0_stack[sizeof(mce0_stack)]) - 1;
          np->np_pcpu = (register_t) pc;
          common_tss[0].tss_ist3 = (long) np;
  
          /*
           * DB# stack, runs on ist4.
           */
          np = ((struct nmi_pcpu *) &dbg0_stack[sizeof(dbg0_stack)]) - 1;
          np->np_pcpu = (register_t) pc;
          common_tss[0].tss_ist4 = (long) np;
          
          /* Set the IO permission bitmap (empty due to tss seg limit) */
          common_tss[0].tss_iobase = sizeof(struct amd64tss) + IOPERM_BITMAP_SIZE;
  
          gsel_tss = GSEL(GPROC0_SEL, SEL_KPL);
          ltr(gsel_tss);
  
          amd64_conf_fast_syscall();
  
          /*
           * Temporary forge some valid pointer to PCB, for exception
           * handlers.  It is reinitialized properly below after FPU is
           * set up.  Also set up td_critnest to short-cut the page
           * fault handler.
           */
          cpu_max_ext_state_size = sizeof(struct savefpu);
          thread0.td_pcb = get_pcb_td(&thread0);
          thread0.td_critnest = 1;
  
          /*
           * The console and kdb should be initialized even earlier than here,
           * but some console drivers don't work until after getmemsize().
           * Default to late console initialization to support these drivers.
           * This loses mainly printf()s in getmemsize() and early debugging.
           */
          late_console = 1;
          TUNABLE_INT_FETCH("debug.late_console", &late_console);
          if (!late_console) {
                  cninit();
                  amd64_kdb_init();
          }
  
          getmemsize(kmdp, physfree);
          init_param2(physmem);
  
          /* now running on new page tables, configured,and u/iom is accessible */
  
          if (late_console)
                  cninit();
  
  #ifdef DEV_ISA
  #ifdef DEV_ATPIC
          elcr_probe();
          atpic_startup();
  #else
          /* Reset and mask the atpics and leave them shut down. */
          atpic_reset();
  
          /*
           * Point the ICU spurious interrupt vectors at the APIC spurious
           * interrupt handler.
           */
          setidt(IDT_IO_INTS + 7, IDTVEC(spuriousint), SDT_SYSIGT, SEL_KPL, 0);
          setidt(IDT_IO_INTS + 15, IDTVEC(spuriousint), SDT_SYSIGT, SEL_KPL, 0);
  #endif
  #else
  #error "have you forgotten the isa device?";
  #endif
  
          if (late_console)
                  amd64_kdb_init();
  
          msgbufinit(msgbufp, msgbufsize);
          fpuinit();
  
          /*
           * Set up thread0 pcb after fpuinit calculated pcb + fpu save
           * area size.  Zero out the extended state header in fpu save
           * area.
           */
          thread0.td_pcb = get_pcb_td(&thread0);
          thread0.td_pcb->pcb_save = get_pcb_user_save_td(&thread0);
          bzero(get_pcb_user_save_td(&thread0), cpu_max_ext_state_size);
          if (use_xsave) {
                  xhdr = (struct xstate_hdr *)(get_pcb_user_save_td(&thread0) +
                      1);
                  xhdr->xstate_bv = xsave_mask;
          }
          /* make an initial tss so cpu can get interrupt stack on syscall! */
          rsp0 = (vm_offset_t)thread0.td_pcb;
          /* Ensure the stack is aligned to 16 bytes */
          rsp0 &= ~0xFul;
          common_tss[0].tss_rsp0 = rsp0;
          PCPU_SET(rsp0, rsp0);
          PCPU_SET(pti_rsp0, ((vm_offset_t)PCPU_PTR(pti_stack) +
              PC_PTI_STACK_SZ * sizeof(uint64_t)) & ~0xful);
          PCPU_SET(curpcb, thread0.td_pcb);
  
          /* transfer to user mode */
  
          _ucodesel = GSEL(GUCODE_SEL, SEL_UPL);
          _udatasel = GSEL(GUDATA_SEL, SEL_UPL);
          _ucode32sel = GSEL(GUCODE32_SEL, SEL_UPL);
          _ufssel = GSEL(GUFS32_SEL, SEL_UPL);
          _ugssel = GSEL(GUGS32_SEL, SEL_UPL);
  
          load_ds(_udatasel);
          load_es(_udatasel);
          load_fs(_ufssel);
  
          /* setup proc 0's pcb */
          thread0.td_pcb->pcb_flags = 0;
          thread0.td_frame = &proc0_tf;
  
          env = kern_getenv("kernelname");
          if (env != NULL)
                  strlcpy(kernelname, env, sizeof(kernelname));
  
          cpu_probe_amdc1e();
  
  #ifdef FDT
          x86_init_fdt();
  #endif
          thread0.td_critnest = 0;
  
          TUNABLE_INT_FETCH("hw.ibrs_disable", &hw_ibrs_disable);
          TUNABLE_INT_FETCH("hw.spec_store_bypass_disable", &hw_ssb_disable);
          TUNABLE_INT_FETCH("hw.mds_disable", &hw_mds_disable);
  
          /* Location of kernel stack for locore */
          return ((u_int64_t)thread0.td_pcb);
  }
  
  void
  cpu_pcpu_init(struct pcpu *pcpu, int cpuid, size_t size)
  {
  
          pcpu->pc_acpi_id = 0xffffffff;
  }
  
  static int
  smap_sysctl_handler(SYSCTL_HANDLER_ARGS)
  {
          struct bios_smap *smapbase;
          struct bios_smap_xattr smap;
          caddr_t kmdp;
          uint32_t *smapattr;
          int count, error, i;
  
          /* Retrieve the system memory map from the loader. */
          kmdp = preload_search_by_type("elf kernel");
          if (kmdp == NULL)
                  kmdp = preload_search_by_type("elf64 kernel");
          smapbase = (struct bios_smap *)preload_search_info(kmdp,
              MODINFO_METADATA | MODINFOMD_SMAP);
          if (smapbase == NULL)
                  return (0);
          smapattr = (uint32_t *)preload_search_info(kmdp,
              MODINFO_METADATA | MODINFOMD_SMAP_XATTR);
          count = *((uint32_t *)smapbase - 1) / sizeof(*smapbase);
          error = 0;
          for (i = 0; i < count; i++) {
                  smap.base = smapbase[i].base;
                  smap.length = smapbase[i].length;
                  smap.type = smapbase[i].type;
                  if (smapattr != NULL)
                          smap.xattr = smapattr[i];
                  else
                          smap.xattr = 0;
                  error = SYSCTL_OUT(req, &smap, sizeof(smap));
          }
          return (error);
  }
  SYSCTL_PROC(_machdep, OID_AUTO, smap, CTLTYPE_OPAQUE|CTLFLAG_RD, NULL, 0,
      smap_sysctl_handler, "S,bios_smap_xattr", "Raw BIOS SMAP data");
  
  static int
  efi_map_sysctl_handler(SYSCTL_HANDLER_ARGS)
  {
          struct efi_map_header *efihdr;
          caddr_t kmdp;
          uint32_t efisize;
  
          kmdp = preload_search_by_type("elf kernel");
          if (kmdp == NULL)
                  kmdp = preload_search_by_type("elf64 kernel");
          efihdr = (struct efi_map_header *)preload_search_info(kmdp,
              MODINFO_METADATA | MODINFOMD_EFI_MAP);
          if (efihdr == NULL)
                  return (0);
          efisize = *((uint32_t *)efihdr - 1);
          return (SYSCTL_OUT(req, efihdr, efisize));
  }
  SYSCTL_PROC(_machdep, OID_AUTO, efi_map, CTLTYPE_OPAQUE|CTLFLAG_RD, NULL, 0,
      efi_map_sysctl_handler, "S,efi_map_header", "Raw EFI Memory Map");
  
  void
  spinlock_enter(void)
  {
          struct thread *td;
          register_t flags;
  
          td = curthread;
          if (td->td_md.md_spinlock_count == 0) {
                  flags = intr_disable();
                  td->td_md.md_spinlock_count = 1;
                  td->td_md.md_saved_flags = flags;
          } else
                  td->td_md.md_spinlock_count++;
          critical_enter();
  }
  
  void
  spinlock_exit(void)
  {
          struct thread *td;
          register_t flags;
  
          td = curthread;
          critical_exit();
          flags = td->td_md.md_saved_flags;
          td->td_md.md_spinlock_count--;
          if (td->td_md.md_spinlock_count == 0)
                  intr_restore(flags);
  }
  
  /*
   * Construct a PCB from a trapframe. This is called from kdb_trap() where
   * we want to start a backtrace from the function that caused us to enter
   * the debugger. We have the context in the trapframe, but base the trace
   * on the PCB. The PCB doesn't have to be perfect, as long as it contains
   * enough for a backtrace.
   */
  void
  makectx(struct trapframe *tf, struct pcb *pcb)
  {
  
          pcb->pcb_r12 = tf->tf_r12;
          pcb->pcb_r13 = tf->tf_r13;
          pcb->pcb_r14 = tf->tf_r14;
          pcb->pcb_r15 = tf->tf_r15;
          pcb->pcb_rbp = tf->tf_rbp;
          pcb->pcb_rbx = tf->tf_rbx;
          pcb->pcb_rip = tf->tf_rip;
          pcb->pcb_rsp = tf->tf_rsp;
  }
  
  int
  ptrace_set_pc(struct thread *td, unsigned long addr)
  {
  
          td->td_frame->tf_rip = addr;
          set_pcb_flags(td->td_pcb, PCB_FULL_IRET);
          return (0);
  }
  
  int
  ptrace_single_step(struct thread *td)
  {
  
          PROC_LOCK_ASSERT(td->td_proc, MA_OWNED);
          if ((td->td_frame->tf_rflags & PSL_T) == 0) {
                  td->td_frame->tf_rflags |= PSL_T;
                  td->td_dbgflags |= TDB_STEP;
          }
          return (0);
  }
  
  int
  ptrace_clear_single_step(struct thread *td)
  {
          PROC_LOCK_ASSERT(td->td_proc, MA_OWNED);
          td->td_frame->tf_rflags &= ~PSL_T;
          td->td_dbgflags &= ~TDB_STEP;
          return (0);
  }
  
  int
  fill_regs(struct thread *td, struct reg *regs)
  {
          struct trapframe *tp;
  
          tp = td->td_frame;
          return (fill_frame_regs(tp, regs));
  }
  
  int
  fill_frame_regs(struct trapframe *tp, struct reg *regs)
  {
  
          regs->r_r15 = tp->tf_r15;
          regs->r_r14 = tp->tf_r14;
          regs->r_r13 = tp->tf_r13;
          regs->r_r12 = tp->tf_r12;
          regs->r_r11 = tp->tf_r11;
          regs->r_r10 = tp->tf_r10;
          regs->r_r9  = tp->tf_r9;
          regs->r_r8  = tp->tf_r8;
          regs->r_rdi = tp->tf_rdi;
          regs->r_rsi = tp->tf_rsi;
          regs->r_rbp = tp->tf_rbp;
          regs->r_rbx = tp->tf_rbx;
          regs->r_rdx = tp->tf_rdx;
          regs->r_rcx = tp->tf_rcx;
          regs->r_rax = tp->tf_rax;
          regs->r_rip = tp->tf_rip;
          regs->r_cs = tp->tf_cs;
          regs->r_rflags = tp->tf_rflags;
          regs->r_rsp = tp->tf_rsp;
          regs->r_ss = tp->tf_ss;
          if (tp->tf_flags & TF_HASSEGS) {
                  regs->r_ds = tp->tf_ds;
                  regs->r_es = tp->tf_es;
                  regs->r_fs = tp->tf_fs;
                  regs->r_gs = tp->tf_gs;
          } else {
                  regs->r_ds = 0;
                  regs->r_es = 0;
                  regs->r_fs = 0;
                  regs->r_gs = 0;
          }
          regs->r_err = 0;
          regs->r_trapno = 0;
          return (0);
  }
  
  int
  set_regs(struct thread *td, struct reg *regs)
  {
          struct trapframe *tp;
          register_t rflags;
  
          tp = td->td_frame;
          rflags = regs->r_rflags & 0xffffffff;
          if (!EFL_SECURE(rflags, tp->tf_rflags) || !CS_SECURE(regs->r_cs))
                  return (EINVAL);
          tp->tf_r15 = regs->r_r15;
          tp->tf_r14 = regs->r_r14;
          tp->tf_r13 = regs->r_r13;
          tp->tf_r12 = regs->r_r12;
          tp->tf_r11 = regs->r_r11;
          tp->tf_r10 = regs->r_r10;
          tp->tf_r9  = regs->r_r9;
          tp->tf_r8  = regs->r_r8;
          tp->tf_rdi = regs->r_rdi;
          tp->tf_rsi = regs->r_rsi;
          tp->tf_rbp = regs->r_rbp;
          tp->tf_rbx = regs->r_rbx;
          tp->tf_rdx = regs->r_rdx;
          tp->tf_rcx = regs->r_rcx;
          tp->tf_rax = regs->r_rax;
          tp->tf_rip = regs->r_rip;
          tp->tf_cs = regs->r_cs;
          tp->tf_rflags = rflags;
          tp->tf_rsp = regs->r_rsp;
          tp->tf_ss = regs->r_ss;
          if (0) {        /* XXXKIB */
                  tp->tf_ds = regs->r_ds;
                  tp->tf_es = regs->r_es;
                  tp->tf_fs = regs->r_fs;
                  tp->tf_gs = regs->r_gs;
                  tp->tf_flags = TF_HASSEGS;
          }
          set_pcb_flags(td->td_pcb, PCB_FULL_IRET);
          return (0);
  }
  
  /* XXX check all this stuff! */
  /* externalize from sv_xmm */
  static void
  fill_fpregs_xmm(struct savefpu *sv_xmm, struct fpreg *fpregs)
  {
          struct envxmm *penv_fpreg = (struct envxmm *)&fpregs->fpr_env;
          struct envxmm *penv_xmm = &sv_xmm->sv_env;
          int i;
  
          /* pcb -> fpregs */
          bzero(fpregs, sizeof(*fpregs));
  
          /* FPU control/status */
          penv_fpreg->en_cw = penv_xmm->en_cw;
          penv_fpreg->en_sw = penv_xmm->en_sw;
          penv_fpreg->en_tw = penv_xmm->en_tw;
          penv_fpreg->en_opcode = penv_xmm->en_opcode;
          penv_fpreg->en_rip = penv_xmm->en_rip;
          penv_fpreg->en_rdp = penv_xmm->en_rdp;
          penv_fpreg->en_mxcsr = penv_xmm->en_mxcsr;
          penv_fpreg->en_mxcsr_mask = penv_xmm->en_mxcsr_mask;
  
          /* FPU registers */
          for (i = 0; i < 8; ++i)
                  bcopy(sv_xmm->sv_fp[i].fp_acc.fp_bytes, fpregs->fpr_acc[i], 10);
  
          /* SSE registers */
          for (i = 0; i < 16; ++i)
                  bcopy(sv_xmm->sv_xmm[i].xmm_bytes, fpregs->fpr_xacc[i], 16);
  }
  
  /* internalize from fpregs into sv_xmm */
  static void
  set_fpregs_xmm(struct fpreg *fpregs, struct savefpu *sv_xmm)
  {
          struct envxmm *penv_xmm = &sv_xmm->sv_env;
          struct envxmm *penv_fpreg = (struct envxmm *)&fpregs->fpr_env;
          int i;
  
          /* fpregs -> pcb */
          /* FPU control/status */
          penv_xmm->en_cw = penv_fpreg->en_cw;
          penv_xmm->en_sw = penv_fpreg->en_sw;
          penv_xmm->en_tw = penv_fpreg->en_tw;
          penv_xmm->en_opcode = penv_fpreg->en_opcode;
          penv_xmm->en_rip = penv_fpreg->en_rip;
          penv_xmm->en_rdp = penv_fpreg->en_rdp;
          penv_xmm->en_mxcsr = penv_fpreg->en_mxcsr;
          penv_xmm->en_mxcsr_mask = penv_fpreg->en_mxcsr_mask & cpu_mxcsr_mask;
  
          /* FPU registers */
          for (i = 0; i < 8; ++i)
                  bcopy(fpregs->fpr_acc[i], sv_xmm->sv_fp[i].fp_acc.fp_bytes, 10);
  
          /* SSE registers */
          for (i = 0; i < 16; ++i)
                  bcopy(fpregs->fpr_xacc[i], sv_xmm->sv_xmm[i].xmm_bytes, 16);
  }
  
  /* externalize from td->pcb */
  int
  fill_fpregs(struct thread *td, struct fpreg *fpregs)
  {
  
          KASSERT(td == curthread || TD_IS_SUSPENDED(td) ||
              P_SHOULDSTOP(td->td_proc),
              ("not suspended thread %p", td));
          fpugetregs(td);
          fill_fpregs_xmm(get_pcb_user_save_td(td), fpregs);
          return (0);
  }
  
  /* internalize to td->pcb */
  int
  set_fpregs(struct thread *td, struct fpreg *fpregs)
  {
  
          critical_enter();
          set_fpregs_xmm(fpregs, get_pcb_user_save_td(td));
          fpuuserinited(td);
          critical_exit();
          return (0);
  }
  
  /*
   * Get machine context.
   */
  int
  get_mcontext(struct thread *td, mcontext_t *mcp, int flags)
  {
          struct pcb *pcb;
          struct trapframe *tp;
  
          pcb = td->td_pcb;
          tp = td->td_frame;
          PROC_LOCK(curthread->td_proc);
          mcp->mc_onstack = sigonstack(tp->tf_rsp);
          PROC_UNLOCK(curthread->td_proc);
          mcp->mc_r15 = tp->tf_r15;
          mcp->mc_r14 = tp->tf_r14;
          mcp->mc_r13 = tp->tf_r13;
          mcp->mc_r12 = tp->tf_r12;
          mcp->mc_r11 = tp->tf_r11;
          mcp->mc_r10 = tp->tf_r10;
          mcp->mc_r9  = tp->tf_r9;
          mcp->mc_r8  = tp->tf_r8;
          mcp->mc_rdi = tp->tf_rdi;
          mcp->mc_rsi = tp->tf_rsi;
          mcp->mc_rbp = tp->tf_rbp;
          mcp->mc_rbx = tp->tf_rbx;
          mcp->mc_rcx = tp->tf_rcx;
          mcp->mc_rflags = tp->tf_rflags;
          if (flags & GET_MC_CLEAR_RET) {
                  mcp->mc_rax = 0;
                  mcp->mc_rdx = 0;
                  mcp->mc_rflags &= ~PSL_C;
          } else {
                  mcp->mc_rax = tp->tf_rax;
                  mcp->mc_rdx = tp->tf_rdx;
          }
          mcp->mc_rip = tp->tf_rip;
          mcp->mc_cs = tp->tf_cs;
          mcp->mc_rsp = tp->tf_rsp;
          mcp->mc_ss = tp->tf_ss;
          mcp->mc_ds = tp->tf_ds;
          mcp->mc_es = tp->tf_es;
          mcp->mc_fs = tp->tf_fs;
          mcp->mc_gs = tp->tf_gs;
          mcp->mc_flags = tp->tf_flags;
          mcp->mc_len = sizeof(*mcp);
          get_fpcontext(td, mcp, NULL, 0);
          update_pcb_bases(pcb);
          mcp->mc_fsbase = pcb->pcb_fsbase;
          mcp->mc_gsbase = pcb->pcb_gsbase;
          mcp->mc_xfpustate = 0;
          mcp->mc_xfpustate_len = 0;
          bzero(mcp->mc_spare, sizeof(mcp->mc_spare));
          return (0);
  }
  
  /*
   * Set machine context.
   *
   * However, we don't set any but the user modifiable flags, and we won't
   * touch the cs selector.
   */
  int
  set_mcontext(struct thread *td, mcontext_t *mcp)
  {
          struct pcb *pcb;
          struct trapframe *tp;
          char *xfpustate;
          long rflags;
          int ret;
  
          pcb = td->td_pcb;
          tp = td->td_frame;
          if (mcp->mc_len != sizeof(*mcp) ||
              (mcp->mc_flags & ~_MC_FLAG_MASK) != 0)
                  return (EINVAL);
          rflags = (mcp->mc_rflags & PSL_USERCHANGE) |
              (tp->tf_rflags & ~PSL_USERCHANGE);
          if (mcp->mc_flags & _MC_HASFPXSTATE) {
                  if (mcp->mc_xfpustate_len > cpu_max_ext_state_size -
                      sizeof(struct savefpu))
                          return (EINVAL);
                  xfpustate = __builtin_alloca(mcp->mc_xfpustate_len);
                  ret = copyin((void *)mcp->mc_xfpustate, xfpustate,
                      mcp->mc_xfpustate_len);
                  if (ret != 0)
                          return (ret);
          } else
                  xfpustate = NULL;
          ret = set_fpcontext(td, mcp, xfpustate, mcp->mc_xfpustate_len);
          if (ret != 0)
                  return (ret);
          tp->tf_r15 = mcp->mc_r15;
          tp->tf_r14 = mcp->mc_r14;
          tp->tf_r13 = mcp->mc_r13;
          tp->tf_r12 = mcp->mc_r12;
          tp->tf_r11 = mcp->mc_r11;
          tp->tf_r10 = mcp->mc_r10;
          tp->tf_r9  = mcp->mc_r9;
          tp->tf_r8  = mcp->mc_r8;
          tp->tf_rdi = mcp->mc_rdi;
          tp->tf_rsi = mcp->mc_rsi;
          tp->tf_rbp = mcp->mc_rbp;
          tp->tf_rbx = mcp->mc_rbx;
          tp->tf_rdx = mcp->mc_rdx;
          tp->tf_rcx = mcp->mc_rcx;
          tp->tf_rax = mcp->mc_rax;
          tp->tf_rip = mcp->mc_rip;
          tp->tf_rflags = rflags;
          tp->tf_rsp = mcp->mc_rsp;
          tp->tf_ss = mcp->mc_ss;
          tp->tf_flags = mcp->mc_flags;
          if (tp->tf_flags & TF_HASSEGS) {
                  tp->tf_ds = mcp->mc_ds;
                  tp->tf_es = mcp->mc_es;
                  tp->tf_fs = mcp->mc_fs;
                  tp->tf_gs = mcp->mc_gs;
          }
          set_pcb_flags(pcb, PCB_FULL_IRET);
          if (mcp->mc_flags & _MC_HASBASES) {
                  pcb->pcb_fsbase = mcp->mc_fsbase;
                  pcb->pcb_gsbase = mcp->mc_gsbase;
          }
          return (0);
  }
  
  static void
  get_fpcontext(struct thread *td, mcontext_t *mcp, char *xfpusave,
      size_t xfpusave_len)
  {
          size_t max_len, len;
  
          mcp->mc_ownedfp = fpugetregs(td);
          bcopy(get_pcb_user_save_td(td), &mcp->mc_fpstate[0],
              sizeof(mcp->mc_fpstate));
          mcp->mc_fpformat = fpuformat();
          if (!use_xsave || xfpusave_len == 0)
                  return;
          max_len = cpu_max_ext_state_size - sizeof(struct savefpu);
          len = xfpusave_len;
          if (len > max_len) {
                  len = max_len;
                  bzero(xfpusave + max_len, len - max_len);
          }
          mcp->mc_flags |= _MC_HASFPXSTATE;
          mcp->mc_xfpustate_len = len;
          bcopy(get_pcb_user_save_td(td) + 1, xfpusave, len);
  }
  
  static int
  set_fpcontext(struct thread *td, mcontext_t *mcp, char *xfpustate,
      size_t xfpustate_len)
  {
          int error;
  
          if (mcp->mc_fpformat == _MC_FPFMT_NODEV)
                  return (0);
          else if (mcp->mc_fpformat != _MC_FPFMT_XMM)
                  return (EINVAL);
          else if (mcp->mc_ownedfp == _MC_FPOWNED_NONE) {
                  /* We don't care what state is left in the FPU or PCB. */
                  fpstate_drop(td);
                  error = 0;
          } else if (mcp->mc_ownedfp == _MC_FPOWNED_FPU ||
              mcp->mc_ownedfp == _MC_FPOWNED_PCB) {
                  error = fpusetregs(td, (struct savefpu *)&mcp->mc_fpstate,
                      xfpustate, xfpustate_len);
          } else
                  return (EINVAL);
          return (error);
  }
  
  void
  fpstate_drop(struct thread *td)
  {
  
          KASSERT(PCB_USER_FPU(td->td_pcb), ("fpstate_drop: kernel-owned fpu"));
          critical_enter();
          if (PCPU_GET(fpcurthread) == td)
                  fpudrop();
          /*
           * XXX force a full drop of the fpu.  The above only drops it if we
           * owned it.
           *
           * XXX I don't much like fpugetuserregs()'s semantics of doing a full
           * drop.  Dropping only to the pcb matches fnsave's behaviour.
           * We only need to drop to !PCB_INITDONE in sendsig().  But
           * sendsig() is the only caller of fpugetuserregs()... perhaps we just
           * have too many layers.
           */
          clear_pcb_flags(curthread->td_pcb,
              PCB_FPUINITDONE | PCB_USERFPUINITDONE);
          critical_exit();
  }
  
  int
  fill_dbregs(struct thread *td, struct dbreg *dbregs)
  {
          struct pcb *pcb;
  
          if (td == NULL) {
                  dbregs->dr[0] = rdr0();
                  dbregs->dr[1] = rdr1();
                  dbregs->dr[2] = rdr2();
                  dbregs->dr[3] = rdr3();
                  dbregs->dr[6] = rdr6();
                  dbregs->dr[7] = rdr7();
          } else {
                  pcb = td->td_pcb;
                  dbregs->dr[0] = pcb->pcb_dr0;
                  dbregs->dr[1] = pcb->pcb_dr1;
                  dbregs->dr[2] = pcb->pcb_dr2;
                  dbregs->dr[3] = pcb->pcb_dr3;
                  dbregs->dr[6] = pcb->pcb_dr6;
                  dbregs->dr[7] = pcb->pcb_dr7;
          }
          dbregs->dr[4] = 0;
          dbregs->dr[5] = 0;
          dbregs->dr[8] = 0;
          dbregs->dr[9] = 0;
          dbregs->dr[10] = 0;
          dbregs->dr[11] = 0;
          dbregs->dr[12] = 0;
          dbregs->dr[13] = 0;
          dbregs->dr[14] = 0;
          dbregs->dr[15] = 0;
          return (0);
  }
  
  int
  set_dbregs(struct thread *td, struct dbreg *dbregs)
  {
          struct pcb *pcb;
          int i;
  
          if (td == NULL) {
                  load_dr0(dbregs->dr[0]);
                  load_dr1(dbregs->dr[1]);
                  load_dr2(dbregs->dr[2]);
                  load_dr3(dbregs->dr[3]);
                  load_dr6(dbregs->dr[6]);
                  load_dr7(dbregs->dr[7]);
          } else {
                  /*
                   * Don't let an illegal value for dr7 get set.  Specifically,
                   * check for undefined settings.  Setting these bit patterns
                   * result in undefined behaviour and can lead to an unexpected
                   * TRCTRAP or a general protection fault right here.
                   * Upper bits of dr6 and dr7 must not be set
                   */
                  for (i = 0; i < 4; i++) {
                          if (DBREG_DR7_ACCESS(dbregs->dr[7], i) == 0x02)
                                  return (EINVAL);
                          if (td->td_frame->tf_cs == _ucode32sel &&
                              DBREG_DR7_LEN(dbregs->dr[7], i) == DBREG_DR7_LEN_8)
                                  return (EINVAL);
                  }
                  if ((dbregs->dr[6] & 0xffffffff00000000ul) != 0 ||
                      (dbregs->dr[7] & 0xffffffff00000000ul) != 0)
                          return (EINVAL);
  
                  pcb = td->td_pcb;
  
                  /*
                   * Don't let a process set a breakpoint that is not within the
                   * process's address space.  If a process could do this, it
                   * could halt the system by setting a breakpoint in the kernel
                   * (if ddb was enabled).  Thus, we need to check to make sure
                   * that no breakpoints are being enabled for addresses outside
                   * process's address space.
                   *
                   * XXX - what about when the watched area of the user's
                   * address space is written into from within the kernel
                   * ... wouldn't that still cause a breakpoint to be generated
                   * from within kernel mode?
                   */
  
                  if (DBREG_DR7_ENABLED(dbregs->dr[7], 0)) {
                          /* dr0 is enabled */
                          if (dbregs->dr[0] >= VM_MAXUSER_ADDRESS)
                                  return (EINVAL);
                  }
                  if (DBREG_DR7_ENABLED(dbregs->dr[7], 1)) {
                          /* dr1 is enabled */
                          if (dbregs->dr[1] >= VM_MAXUSER_ADDRESS)
                                  return (EINVAL);
                  }
                  if (DBREG_DR7_ENABLED(dbregs->dr[7], 2)) {
                          /* dr2 is enabled */
                          if (dbregs->dr[2] >= VM_MAXUSER_ADDRESS)
                                  return (EINVAL);
                  }
                  if (DBREG_DR7_ENABLED(dbregs->dr[7], 3)) {
                          /* dr3 is enabled */
                          if (dbregs->dr[3] >= VM_MAXUSER_ADDRESS)
                                  return (EINVAL);
                  }
  
                  pcb->pcb_dr0 = dbregs->dr[0];
                  pcb->pcb_dr1 = dbregs->dr[1];
                  pcb->pcb_dr2 = dbregs->dr[2];
                  pcb->pcb_dr3 = dbregs->dr[3];
                  pcb->pcb_dr6 = dbregs->dr[6];
                  pcb->pcb_dr7 = dbregs->dr[7];
  
                  set_pcb_flags(pcb, PCB_DBREGS);
          }
  
          return (0);
  }
  
  void
  reset_dbregs(void)
  {
  
          load_dr7(0);    /* Turn off the control bits first */
          load_dr0(0);
          load_dr1(0);
          load_dr2(0);
          load_dr3(0);
          load_dr6(0);
  }
  
  /*
   * Return > 0 if a hardware breakpoint has been hit, and the
   * breakpoint was in user space.  Return 0, otherwise.
   */
  int
  user_dbreg_trap(register_t dr6)
  {
          u_int64_t dr7;
          u_int64_t bp;       /* breakpoint bits extracted from dr6 */
          int nbp;            /* number of breakpoints that triggered */
          caddr_t addr[4];    /* breakpoint addresses */
          int i;
  
          bp = dr6 & DBREG_DR6_BMASK;
          if (bp == 0) {
                  /*
                   * None of the breakpoint bits are set meaning this
                   * trap was not caused by any of the debug registers
                   */
                  return 0;
          }
  
          dr7 = rdr7();
          if ((dr7 & 0x000000ff) == 0) {
                  /*
                   * all GE and LE bits in the dr7 register are zero,
                   * thus the trap couldn't have been caused by the
                   * hardware debug registers
                   */
                  return 0;
          }
  
          nbp = 0;
  
          /*
           * at least one of the breakpoints were hit, check to see
           * which ones and if any of them are user space addresses
           */
  
          if (bp & 0x01) {
                  addr[nbp++] = (caddr_t)rdr0();
          }
          if (bp & 0x02) {
                  addr[nbp++] = (caddr_t)rdr1();
          }
          if (bp & 0x04) {
                  addr[nbp++] = (caddr_t)rdr2();
          }
          if (bp & 0x08) {
                  addr[nbp++] = (caddr_t)rdr3();
          }
  
          for (i = 0; i < nbp; i++) {
                  if (addr[i] < (caddr_t)VM_MAXUSER_ADDRESS) {
                          /*
                           * addr[i] is in user space
                           */
                          return nbp;
                  }
          }
  
          /*
           * None of the breakpoints are in user space.
           */
          return 0;
  }
  
  /*
   * The pcb_flags is only modified by current thread, or by other threads
   * when current thread is stopped.  However, current thread may change it
   * from the interrupt context in cpu_switch(), or in the trap handler.
   * When we read-modify-write pcb_flags from C sources, compiler may generate
   * code that is not atomic regarding the interrupt handler.  If a trap or
   * interrupt happens and any flag is modified from the handler, it can be
   * clobbered with the cached value later.  Therefore, we implement setting
   * and clearing flags with single-instruction functions, which do not race
   * with possible modification of the flags from the trap or interrupt context,
   * because traps and interrupts are executed only on instruction boundary.
   */
  void
  set_pcb_flags_raw(struct pcb *pcb, const u_int flags)
  {
  
          __asm __volatile("orl %1,%0"
              : "=m" (pcb->pcb_flags) : "ir" (flags), "m" (pcb->pcb_flags)
              : "cc", "memory");
  
  }
  
  /*
   * The support for RDFSBASE, WRFSBASE and similar instructions for %gs
   * base requires that kernel saves MSR_FSBASE and MSR_{K,}GSBASE into
   * pcb if user space modified the bases.  We must save on the context
   * switch or if the return to usermode happens through the doreti.
   *
   * Tracking of both events is performed by the pcb flag PCB_FULL_IRET,
   * which have a consequence that the base MSRs must be saved each time
   * the PCB_FULL_IRET flag is set.  We disable interrupts to sync with
   * context switches.
   */
  void
  set_pcb_flags(struct pcb *pcb, const u_int flags)
  {
          register_t r;
  
          if (curpcb == pcb &&
              (flags & PCB_FULL_IRET) != 0 &&
              (pcb->pcb_flags & PCB_FULL_IRET) == 0 &&
              (cpu_stdext_feature & CPUID_STDEXT_FSGSBASE) != 0) {
                  r = intr_disable();
                  if ((pcb->pcb_flags & PCB_FULL_IRET) == 0) {
                          if (rfs() == _ufssel)
                                  pcb->pcb_fsbase = rdfsbase();
                          if (rgs() == _ugssel)
                                  pcb->pcb_gsbase = rdmsr(MSR_KGSBASE);
                  }
                  set_pcb_flags_raw(pcb, flags);
                  intr_restore(r);
          } else {
                  set_pcb_flags_raw(pcb, flags);
          }
  }
  
  void
  clear_pcb_flags(struct pcb *pcb, const u_int flags)
  {
  
          __asm __volatile("andl %1,%0"
              : "=m" (pcb->pcb_flags) : "ir" (~flags), "m" (pcb->pcb_flags)
              : "cc", "memory");
  }
  
  #ifdef KDB
  
  /*
   * Provide inb() and outb() as functions.  They are normally only available as
   * inline functions, thus cannot be called from the debugger.
   */
  
  /* silence compiler warnings */
  u_char inb_(u_short);
  void outb_(u_short, u_char);
  
  u_char
  inb_(u_short port)
  {
          return inb(port);
  }
  
  void
  outb_(u_short port, u_char data)
  {
          outb(port, data);
  }
  
  #endif /* KDB */

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