/*      $NetBSD: trap.c,v 1.310 2025/06/20 17:02:18 bouyer Exp $        */

/*-
 * Copyright (c) 1998, 2000, 2005, 2006, 2007, 2008 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Charles M. Hannum.
 *
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. 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 FOUNDATION 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.
 */

/*-
 * Copyright (c) 1990 The Regents of the University of California.
 * All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * the University of Utah, and William Jolitz.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. 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.
 *
 *      @(#)trap.c      7.4 (Berkeley) 5/13/91
 */

/*
 * 386 Trap and System call handling
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: trap.c,v 1.310 2025/06/20 17:02:18 bouyer Exp $");

#include "opt_ddb.h"
#include "opt_kgdb.h"
#include "opt_lockdebug.h"
#include "opt_multiprocessor.h"
#include "opt_xen.h"
#include "opt_dtrace.h"
#include "opt_compat_netbsd.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/proc.h>
#include <sys/acct.h>
#include <sys/kauth.h>
#include <sys/kernel.h>
#include <sys/kmem.h>
#include <sys/ras.h>
#include <sys/signal.h>
#include <sys/syscall.h>
#include <sys/cpu.h>
#include <sys/ucontext.h>

#include <uvm/uvm_extern.h>

#include <machine/cpufunc.h>
#include <machine/psl.h>
#include <machine/reg.h>
#include <machine/trap.h>
#include <machine/userret.h>
#include <machine/db_machdep.h>
#include <machine/pmap_private.h>

#include "mca.h"
#if NMCA > 0
#include <machine/mca_machdep.h>
#endif

#include <x86/dbregs.h>
#include <x86/nmi.h>

#include "isa.h"

#include <sys/kgdb.h>

#ifdef KDTRACE_HOOKS
#include <sys/dtrace_bsd.h>

/*
 * This is a hook which is initialized by the dtrace module
 * to handle traps which might occur during DTrace probe
 * execution.
 */
dtrace_trap_func_t      dtrace_trap_func = NULL;

dtrace_doubletrap_func_t        dtrace_doubletrap_func = NULL;
#endif

void trap(struct trapframe *);
void trap_tss(struct i386tss *, int, int);
void trap_return_fault_return(struct trapframe *) __dead;
#ifndef XENPV
int ss_shadow(struct trapframe *tf);
#endif

const char * const trap_type[] = {
        "privileged instruction fault",         /*  0 T_PRIVINFLT */
        "breakpoint trap",                      /*  1 T_BPTFLT */
        "arithmetic trap",                      /*  2 T_ARITHTRAP */
        "asynchronous system trap",             /*  3 T_ASTFLT */
        "protection fault",                     /*  4 T_PROTFLT */
        "trace trap",                           /*  5 T_TRCTRAP */
        "page fault",                           /*  6 T_PAGEFLT */
        "alignment fault",                      /*  7 T_ALIGNFLT */
        "integer divide fault",                 /*  8 T_DIVIDE */
        "non-maskable interrupt",               /*  9 T_NMI */
        "overflow trap",                        /* 10 T_OFLOW */
        "bounds check fault",                   /* 11 T_BOUND */
        "FPU not available fault",              /* 12 T_DNA */
        "double fault",                         /* 13 T_DOUBLEFLT */
        "FPU operand fetch fault",              /* 14 T_FPOPFLT */
        "invalid TSS fault",                    /* 15 T_TSSFLT */
        "segment not present fault",            /* 16 T_SEGNPFLT */
        "stack fault",                          /* 17 T_STKFLT */
        "machine check fault",                  /* 18 T_MCA */
        "SSE FP exception",                     /* 19 T_XMM */
        "reserved trap",                        /* 20 T_RESERVED */
};
int     trap_types = __arraycount(trap_type);

#ifdef DEBUG
int     trapdebug = 0;
#endif

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

#ifdef TRAP_SIGDEBUG
static void sigdebug(const struct trapframe *, const ksiginfo_t *, int);
#define SIGDEBUG(a, b, c) sigdebug(a, b, c)
#else
#define SIGDEBUG(a, b, c)
#endif

void
trap_tss(struct i386tss *tss, int trapno, int code)
{
        struct trapframe tf;

        tf.tf_gs = tss->tss_gs;
        tf.tf_fs = tss->tss_fs;
        tf.tf_es = tss->__tss_es;
        tf.tf_ds = tss->__tss_ds;
        tf.tf_edi = tss->__tss_edi;
        tf.tf_esi = tss->__tss_esi;
        tf.tf_ebp = tss->tss_ebp;
        tf.tf_ebx = tss->__tss_ebx;
        tf.tf_edx = tss->__tss_edx;
        tf.tf_ecx = tss->__tss_ecx;
        tf.tf_eax = tss->__tss_eax;
        tf.tf_trapno = trapno;
        tf.tf_err = code | TC_TSS;
        tf.tf_eip = tss->__tss_eip;
        tf.tf_cs = tss->__tss_cs;
        tf.tf_eflags = tss->__tss_eflags;
        tf.tf_esp = tss->tss_esp;
        tf.tf_ss = tss->__tss_ss;
        trap(&tf);
}

static void *
onfault_handler(const struct pcb *pcb, const struct trapframe *tf)
{
        struct onfault_table {
                uintptr_t start;
                uintptr_t end;
                void *handler;
        };
        extern const struct onfault_table onfault_table[];
        const struct onfault_table *p;
        uintptr_t pc;

        if (pcb->pcb_onfault != NULL) {
                return pcb->pcb_onfault;
        }

        pc = tf->tf_eip;
        for (p = onfault_table; p->start; p++) {
                if (p->start <= pc && pc < p->end) {
                        return p->handler;
                }
        }
        return NULL;
}

static void
trap_print(const struct trapframe *frame, const lwp_t *l)
{
        const int type = frame->tf_trapno;

        if (frame->tf_trapno < trap_types) {
                printf("fatal %s", trap_type[type]);
        } else {
                printf("unknown trap %d", type);
        }
        printf(" in %s mode\n", (type & T_USER) ? "user" : "supervisor");

        printf("trap type %d code %#x eip %#x cs %#x eflags %#x cr2 %#lx "
            "ilevel %#x esp %#x\n",
            type, frame->tf_err, frame->tf_eip, frame->tf_cs, frame->tf_eflags,
            (long)rcr2(), curcpu()->ci_ilevel, frame->tf_esp);

        printf("curlwp %p pid %d lid %d lowest kstack %p\n",
            l, l->l_proc->p_pid, l->l_lid, KSTACK_LOWEST_ADDR(l));
}

#ifndef XENPV
int
ss_shadow(struct trapframe *tf)
{
        struct gate_descriptor *gd;
        struct cpu_info *ci;
        struct idt_vec *iv;
        idt_descriptor_t *idt;
        uintptr_t eip, func;
        size_t i;

        eip = tf->tf_eip;
        ci = curcpu();
        iv = idt_vec_ref(&ci->ci_idtvec);
        idt = iv->iv_idt;

        for (i = 0; i < 256; i++) {
                gd = &idt[i];
                func = (gd->gd_hioffset << 16) | gd->gd_looffset;
                if (eip == func)
                        return 1;
        }

        return 0;
}
#endif

/*
 * trap(frame): exception, fault, and trap interface to BSD kernel.
 *
 * This common code is called from assembly language IDT gate entry routines
 * that prepare a suitable stack frame, and restore this frame after the
 * exception has been processed. Note that the effect is as if the arguments
 * were passed call by reference.
 */
void
trap(struct trapframe *frame)
{
        struct lwp *l = curlwp;
        struct proc *p;
        struct pcb *pcb;
        extern char kcopy_fault[], return_address_fault[];
        struct trapframe *vframe;
        ksiginfo_t ksi;
        void *onfault;
        int type, error = 0;
        uint32_t cr2;
        bool pfail;

        if (__predict_true(l != NULL)) {
                pcb = lwp_getpcb(l);
                p = l->l_proc;
        } else {
                /*
                 * this can happen eg. on break points in early on boot.
                 */
                pcb = NULL;
                p = NULL;
        }
        type = frame->tf_trapno;

#ifdef DEBUG
        if (trapdebug) {
                trap_print(frame, l);
        }
#endif
        if (type != T_NMI && !KERNELMODE(frame->tf_cs)) {
                type |= T_USER;
                l->l_md.md_regs = frame;
                pcb->pcb_cr2 = 0;
        }

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

        switch (type) {

        default:
        we_re_toast:
                trap_print(frame, l);

                if (kdb_trap(type, 0, frame))
                        return;
                if (kgdb_trap(type, frame))
                        return;
                /*
                 * If this is a breakpoint, don't panic if we're not connected.
                 */
                if (type == T_BPTFLT && kgdb_disconnected()) {
                        printf("kgdb: ignored %s\n", trap_type[type]);
                        return;
                }
                panic("trap");
                /*NOTREACHED*/

        case T_PROTFLT:
        case T_SEGNPFLT:
        case T_ALIGNFLT:
        case T_STKFLT:
        case T_TSSFLT:
                if (p == NULL)
                        goto we_re_toast;
                /* Check for copyin/copyout fault. */
                onfault = onfault_handler(pcb, frame);
                if (onfault != NULL) {
copyefault:
                        error = EFAULT;
copyfault:
                        frame->tf_eip = (uintptr_t)onfault;
                        frame->tf_eax = error;
                        return;
                }

                /*
                 * Check for failure during return to user mode.
                 * This can happen loading invalid values into the segment
                 * registers, or during the 'iret' itself.
                 *
                 * We do this by looking at the instruction we faulted on.
                 * The specific instructions we recognize only happen when
                 * returning from a trap, syscall, or interrupt.
                 */

kernelfault:
                KSI_INIT_TRAP(&ksi);
                ksi.ksi_signo = SIGSEGV;
                ksi.ksi_code = SEGV_ACCERR;
                ksi.ksi_trap = type;

                switch (*(u_char *)frame->tf_eip) {
                case 0xcf:      /* iret */
                        /*
                         * The 'iret' instruction faulted, so we have the
                         * 'user' registers saved after the kernel %eip:%cs:%fl
                         * of the 'iret' and below that the user %eip:%cs:%fl
                         * the 'iret' was processing.
                         * We must delete the 3 words of kernel return address
                         * from the stack to generate a normal stack frame
                         * (eg for sending a SIGSEGV).
                         */
                        vframe = (void *)((int *)frame + 3);
                        if (KERNELMODE(vframe->tf_cs))
                                goto we_re_toast;
                        memmove(vframe, frame,
                            offsetof(struct trapframe, tf_eip));
                        /* Set the faulting address to the user %eip */
                        ksi.ksi_addr = (void *)vframe->tf_eip;
                        break;
                case 0x8e:
                        switch (*(uint32_t *)frame->tf_eip) {
                        case 0x8e242c8e:        /* mov (%esp,%gs), then */
                        case 0x0424648e:        /* mov 0x4(%esp),%fs */
                        case 0x0824448e:        /* mov 0x8(%esp),%es */
                        case 0x0c245c8e:        /* mov 0xc(%esp),%ds */
                                break;
                        default:
                                goto we_re_toast;
                        }
                        /*
                         * We faulted loading one of the user segment registers.
                         * The stack frame containing the user registers is
                         * still valid and is just below the %eip:%cs:%fl of
                         * the kernel fault frame.
                         */
                        vframe = (void *)(&frame->tf_eflags + 1);
                        if (KERNELMODE(vframe->tf_cs))
                                goto we_re_toast;
                        /* There is no valid address for the fault */
                        break;
                default:
                        goto we_re_toast;
                }
                /*
                 * We might have faulted trying to execute the
                 * trampoline for a local (nested) signal handler.
                 * Only generate SIGSEGV if the user %cs isn't changed.
                 * (This is only strictly necessary in the 'iret' case.)
                 */
                if (!pmap_exec_fixup(&p->p_vmspace->vm_map, vframe, pcb)) {
                        /* Save outer frame for any signal return */
                        l->l_md.md_regs = vframe;
                        SIGDEBUG(vframe, &ksi, error);
                        (*p->p_emul->e_trapsignal)(l, &ksi);
                }
                /* Return to user by reloading the user frame */
                trap_return_fault_return(vframe);
                /* NOTREACHED */

        case T_PROTFLT|T_USER:          /* protection fault */
#if defined(COMPAT_10) || defined(COMPAT_NOMID)
        {
#define LCALLSZ 7
                /* Check for the osyscall lcall instruction. */
                if (frame->tf_eip < VM_MAXUSER_ADDRESS - LCALLSZ &&
                    x86_cpu_is_lcall((const void *)frame->tf_eip) == 0) {

                        /* Advance past the lcall. */
                        frame->tf_eip += LCALLSZ;

                        /* Do the syscall. */
                        p->p_md.md_syscall(frame);
                        goto out;
                }
        }
#endif
                /* FALLTHROUGH */
        case T_TSSFLT|T_USER:
        case T_SEGNPFLT|T_USER:
        case T_STKFLT|T_USER:
        case T_ALIGNFLT|T_USER:
                KSI_INIT_TRAP(&ksi);

                ksi.ksi_addr = (void *)rcr2();
                switch (type) {
                case T_SEGNPFLT|T_USER:
                case T_STKFLT|T_USER:
                        ksi.ksi_signo = SIGBUS;
                        ksi.ksi_code = BUS_ADRERR;
                        break;
                case T_TSSFLT|T_USER:
                        ksi.ksi_signo = SIGBUS;
                        ksi.ksi_code = BUS_OBJERR;
                        break;
                case T_ALIGNFLT|T_USER:
                        ksi.ksi_signo = SIGBUS;
                        ksi.ksi_code = BUS_ADRALN;
                        break;
                case T_PROTFLT|T_USER:
                        /*
                         * If pmap_exec_fixup does something,
                         * let's retry the trap.
                         */
                        if (pmap_exec_fixup(&p->p_vmspace->vm_map, frame, pcb)){
                                goto out;
                        }
                        ksi.ksi_signo = SIGSEGV;
                        ksi.ksi_code = SEGV_ACCERR;
                        break;
                default:
                        KASSERT(0);
                        break;
                }
                goto trapsignal;

        case T_PRIVINFLT|T_USER:        /* privileged instruction fault */
        case T_FPOPFLT|T_USER:          /* coprocessor operand fault */
                KSI_INIT_TRAP(&ksi);
                ksi.ksi_signo = SIGILL;
                ksi.ksi_addr = (void *) frame->tf_eip;
                switch (type) {
                case T_PRIVINFLT|T_USER:
                        ksi.ksi_code = ILL_PRVOPC;
                        break;
                case T_FPOPFLT|T_USER:
                        ksi.ksi_code = ILL_COPROC;
                        break;
                default:
                        ksi.ksi_code = 0;
                        break;
                }
                goto trapsignal;

        case T_ASTFLT|T_USER:
                /* Allow process switch. */
                //curcpu()->ci_data.cpu_nast++;
                if (l->l_pflag & LP_OWEUPC) {
                        l->l_pflag &= ~LP_OWEUPC;
                        ADDUPROF(l);
                }
                goto out;

        case T_BOUND|T_USER:
        case T_OFLOW|T_USER:
        case T_DIVIDE|T_USER:
                KSI_INIT_TRAP(&ksi);
                ksi.ksi_signo = SIGFPE;
                ksi.ksi_addr = (void *)frame->tf_eip;
                switch (type) {
                case T_BOUND|T_USER:
                        ksi.ksi_code = FPE_FLTSUB;
                        break;
                case T_OFLOW|T_USER:
                        ksi.ksi_code = FPE_INTOVF;
                        break;
                case T_DIVIDE|T_USER:
                        ksi.ksi_code = FPE_INTDIV;
                        break;
                default:
                        ksi.ksi_code = 0;
                        break;
                }
                goto trapsignal;

        case T_PAGEFLT:
                /* Allow page faults in kernel mode. */
                if (__predict_false(l == NULL))
                        goto we_re_toast;

                onfault = pcb->pcb_onfault;
                if (onfault == return_address_fault) {
                        goto copyefault;
                }
                if (cpu_intr_p() || (l->l_pflag & LP_INTR) != 0) {
                        goto we_re_toast;
                }

                cr2 = rcr2();

                if (frame->tf_err & PGEX_I) {
                        /* SMEP might have brought us here */
                        if (cr2 > VM_MIN_ADDRESS && cr2 <= VM_MAXUSER_ADDRESS) {
                                printf("prevented execution of %p (SMEP)\n",
                                    (void *)cr2);
                                goto we_re_toast;
                        }
                }

                if ((frame->tf_err & PGEX_P) &&
                    cr2 < VM_MAXUSER_ADDRESS) {
                        /* SMAP might have brought us here */
                        if (onfault_handler(pcb, frame) == NULL) {
                                printf("prevented access to %p (SMAP)\n",
                                    (void *)cr2);
                                goto we_re_toast;
                        }
                }

                goto faultcommon;

        case T_PAGEFLT|T_USER: {        /* page fault */
                register vaddr_t va;
                register struct vmspace *vm;
                register struct vm_map *map;
                vm_prot_t ftype;
                extern struct vm_map *kernel_map;

                cr2 = rcr2();
faultcommon:
                vm = p->p_vmspace;
                if (__predict_false(vm == NULL)) {
                        goto we_re_toast;
                }
                pcb->pcb_cr2 = cr2;
                va = trunc_page((vaddr_t)cr2);
                /*
                 * It is only a kernel address space fault iff:
                 *      1. (type & T_USER) == 0  and
                 *      2. pcb_onfault not set or
                 *      3. pcb_onfault set but supervisor space fault
                 * The last can occur during an exec() copyin where the
                 * argument space is lazy-allocated.
                 */
                if (type == T_PAGEFLT && va >= VM_MIN_KERNEL_ADDRESS)
                        map = kernel_map;
                else
                        map = &vm->vm_map;
                if (frame->tf_err & PGEX_W)
                        ftype = VM_PROT_WRITE;
                else if (frame->tf_err & PGEX_I)
                        ftype = VM_PROT_EXECUTE;
                else
                        ftype = VM_PROT_READ;

#ifdef DIAGNOSTIC
                if (map == kernel_map && va == 0) {
                        printf("trap: bad kernel access at %lx\n", va);
                        goto we_re_toast;
                }
#endif
#ifdef XENPV
                /* Check to see if interrupts are enabled (ie; no events are masked) */
                KASSERT(x86_read_psl() == 0);
#endif
                /* Fault the original page in. */
                onfault = pcb->pcb_onfault;
                pcb->pcb_onfault = NULL;
                error = uvm_fault(map, va, ftype);
                pcb->pcb_onfault = onfault;
                if (error == 0) {
                        if (map != kernel_map && (void *)va >= vm->vm_maxsaddr)
                                uvm_grow(p, va);

                        pfail = false;
                        while (type == T_PAGEFLT) {
                                /*
                                 * we need to switch pmap now if we're in
                                 * the middle of copyin/out.
                                 *
                                 * but we don't need to do so for kcopy as
                                 * it never touch userspace.
                                 */
                                kpreempt_disable();
                                if (curcpu()->ci_want_pmapload) {
                                        onfault = onfault_handler(pcb, frame);
                                        if (onfault != kcopy_fault) {
                                                pmap_load();
                                        }
                                }
                                /*
                                 * We need to keep the pmap loaded and
                                 * so avoid being preempted until back
                                 * into the copy functions.  Disable
                                 * interrupts at the hardware level before
                                 * re-enabling preemption.  Interrupts
                                 * will be re-enabled by 'iret' when
                                 * returning back out of the trap stub.
                                 * They'll only be re-enabled when the
                                 * program counter is once again in
                                 * the copy functions, and so visible
                                 * to cpu_kpreempt_exit().
                                 */
                                x86_disable_intr();
                                l->l_nopreempt--;
                                if (l->l_nopreempt > 0 || !l->l_dopreempt ||
                                    pfail) {
                                        return;
                                }
                                x86_enable_intr();
                                /*
                                 * If preemption fails for some reason,
                                 * don't retry it.  The conditions won't
                                 * change under our nose.
                                 */
                                pfail = kpreempt(0);
                        }
                        goto out;
                }

                if (type == T_PAGEFLT) {
                        onfault = onfault_handler(pcb, frame);
                        if (onfault != NULL)
                                goto copyfault;
                        printf("uvm_fault(%p, %#lx, %d) -> %#x\n",
                            map, va, ftype, error);
                        goto kernelfault;
                }

                KSI_INIT_TRAP(&ksi);
                ksi.ksi_trap = type & ~T_USER;
                ksi.ksi_addr = (void *)cr2;
                switch (error) {
                case EINVAL:
                        ksi.ksi_signo = SIGBUS;
                        ksi.ksi_code = BUS_ADRERR;
                        break;
                case EACCES:
                        ksi.ksi_signo = SIGSEGV;
                        ksi.ksi_code = SEGV_ACCERR;
                        error = EFAULT;
                        break;
                case ENOMEM:
                        ksi.ksi_signo = SIGKILL;
                        printf("UVM: pid %d.%d (%s), uid %d killed: "
                            "out of swap\n", p->p_pid, l->l_lid, p->p_comm,
                            l->l_cred ?  kauth_cred_geteuid(l->l_cred) : -1);
                        break;
                default:
                        ksi.ksi_signo = SIGSEGV;
                        ksi.ksi_code = SEGV_MAPERR;
                        break;
                }

                SIGDEBUG(frame, &ksi, error);
                (*p->p_emul->e_trapsignal)(l, &ksi);
                break;
        }

        case T_TRCTRAP:
                /*
                 * Ignore debug register trace traps due to
                 * accesses in the user's address space, which
                 * can happen under several conditions such as
                 * if a user sets a watchpoint on a buffer and
                 * then passes that buffer to a system call.
                 * We still want to get TRCTRAPS for addresses
                 * in kernel space because that is useful when
                 * debugging the kernel.
                 */
                if (x86_dbregs_user_trap())
                        break;

                goto we_re_toast;

        case T_BPTFLT|T_USER:           /* bpt instruction fault */
        case T_TRCTRAP|T_USER:          /* trace trap */
                /*
                 * Don't go single-stepping into a RAS.
                 */
                if (p->p_raslist == NULL ||
                    (ras_lookup(p, (void *)frame->tf_eip) == (void *)-1)) {
                        KSI_INIT_TRAP(&ksi);
                        ksi.ksi_signo = SIGTRAP;
                        ksi.ksi_trap = type & ~T_USER;
                        if (x86_dbregs_user_trap()) {
                                x86_dbregs_store_dr6(l);
                                ksi.ksi_code = TRAP_DBREG;
                        } else if (type == (T_BPTFLT|T_USER))
                                ksi.ksi_code = TRAP_BRKPT;
                        else
                                ksi.ksi_code = TRAP_TRACE;
                        ksi.ksi_addr = (void *)frame->tf_eip;
                        SIGDEBUG(frame, &ksi, error);
                        (*p->p_emul->e_trapsignal)(l, &ksi);
                }
                break;

        case T_NMI:
                if (nmi_dispatch(frame))
                        return;
                /* NMI can be hooked up to a pushbutton for debugging */
                if (kgdb_trap(type, frame))
                        return;
                if (kdb_trap(type, 0, frame))
                        return;
                /* machine/parity/power fail/"kitchen sink" faults */
#if NMCA > 0
                mca_nmi();
#endif
                x86_nmi();
        }

        if ((type & T_USER) == 0)
                return;
out:
        userret(l);
        return;
trapsignal:
        ksi.ksi_trap = type & ~T_USER;
        SIGDEBUG(frame, &ksi, error);
        (*p->p_emul->e_trapsignal)(l, &ksi);
        userret(l);
}

/* 
 * startlwp: start of a new LWP.
 */
void
startlwp(void *arg)
{
        ucontext_t *uc = arg;
        lwp_t *l = curlwp;
        int error __diagused;

        error = cpu_setmcontext(l, &uc->uc_mcontext, uc->uc_flags);
        KASSERT(error == 0);

        kmem_free(uc, sizeof(ucontext_t));
        userret(l);
}

#ifdef TRAP_SIGDEBUG
static void
frame_dump(const struct trapframe *tf, const struct pcb *pcb)
{
        uint64_t fsd, gsd;

        printf("trapframe %p\n", tf);
        printf("eip 0x%08x  esp 0x%08x  efl 0x%08x\n",
            tf->tf_eip, tf->tf_esp, tf->tf_eflags);
        printf("edi 0x%08x  esi 0x%08x  edx 0x%08x\n",
            tf->tf_edi, tf->tf_esi, tf->tf_edx);
        printf("ecx 0x%08x\n",
            tf->tf_ecx);
        printf("ebp 0x%08x  ebx 0x%08x  eax 0x%08x\n",
            tf->tf_ebp, tf->tf_ebx, tf->tf_eax);
        printf("cs 0x%04x  ds 0x%04x  es 0x%04x  "
               "fs 0x%04x  gs 0x%04x  ss 0x%04x\n",
                tf->tf_cs & 0xffff, tf->tf_ds & 0xffff, tf->tf_es & 0xffff,
                tf->tf_fs & 0xffff, tf->tf_gs & 0xffff, tf->tf_ss & 0xffff);
        memcpy(&fsd, &pcb->pcb_fsd, sizeof(fsd));
        memcpy(&gsd, &pcb->pcb_gsd, sizeof(gsd));
        printf("fsbase 0x%016llx gsbase 0x%016llx\n", fsd, gsd);
        printf("\n");
        hexdump(printf, "Stack dump", tf, 256);
}

static void
sigdebug(const struct trapframe *tf, const ksiginfo_t *ksi, int e)
{
        struct lwp *l = curlwp;
        struct proc *p = l->l_proc;

        printf("pid %d.%d (%s): signal %d code=%d (trap %x) "
            "@eip %#x addr %#x error=%d\n",
            p->p_pid, l->l_lid, p->p_comm, ksi->ksi_signo, ksi->ksi_code,
            tf->tf_trapno, tf->tf_eip, rcr2(), e);
        frame_dump(tf, lwp_getpcb(l));
}
#endif