/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (c) 2004 Tim J. Robbins
 * Copyright (c) 2003 Peter Wemm
 * Copyright (c) 2002 Doug Rabson
 * Copyright (c) 1998-1999 Andrew Gallatin
 * Copyright (c) 1994-1996 Søren Schmidt
 * All rights reserved.
 *
 * 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
 *    in this position and unchanged.
 * 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. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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.
 */

#ifndef COMPAT_FREEBSD32
#error "Unable to compile Linux-emulator due to missing COMPAT_FREEBSD32 option!"
#endif

#define __ELF_WORD_SIZE 32

#include <sys/param.h>
#include <sys/exec.h>
#include <sys/imgact.h>
#include <sys/imgact_elf.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/module.h>
#include <sys/mutex.h>
#include <sys/proc.h>
#include <sys/stddef.h>
#include <sys/syscallsubr.h>
#include <sys/sysctl.h>
#include <sys/sysent.h>

#include <vm/pmap.h>
#include <vm/vm.h>
#include <vm/vm_map.h>
#include <vm/vm_param.h>

#include <machine/md_var.h>
#include <machine/trap.h>

#include <x86/linux/linux_x86.h>
#include <amd64/linux32/linux.h>
#include <amd64/linux32/linux32_proto.h>
#include <compat/linux/linux_elf.h>
#include <compat/linux/linux_emul.h>
#include <compat/linux/linux_fork.h>
#include <compat/linux/linux_ioctl.h>
#include <compat/linux/linux_mib.h>
#include <compat/linux/linux_misc.h>
#include <compat/linux/linux_signal.h>
#include <compat/linux/linux_util.h>
#include <compat/linux/linux_vdso.h>

#include <x86/linux/linux_x86_sigframe.h>

MODULE_VERSION(linux, 1);

#define LINUX32_MAXUSER         ((1ul << 32) - PAGE_SIZE)
#define LINUX32_VDSOPAGE_SIZE   PAGE_SIZE * 2
#define LINUX32_VDSOPAGE        (LINUX32_MAXUSER - LINUX32_VDSOPAGE_SIZE)
#define LINUX32_SHAREDPAGE      (LINUX32_VDSOPAGE - PAGE_SIZE)
                                /*
                                 * PAGE_SIZE - the size
                                 * of the native SHAREDPAGE
                                 */
#define LINUX32_USRSTACK        LINUX32_SHAREDPAGE

static int linux_szsigcode;
static vm_object_t linux_vdso_obj;
static char *linux_vdso_mapping;
extern char _binary_linux32_vdso_so_o_start;
extern char _binary_linux32_vdso_so_o_end;
static vm_offset_t linux_vdso_base;

extern struct sysent linux32_sysent[LINUX32_SYS_MAXSYSCALL];
extern const char *linux32_syscallnames[];

SET_DECLARE(linux_ioctl_handler_set, struct linux_ioctl_handler);

static int      linux_copyout_strings(struct image_params *imgp,
                    uintptr_t *stack_base);
static void     linux_sendsig(sig_t catcher, ksiginfo_t *ksi, sigset_t *mask);
static void     linux_exec_setregs(struct thread *td,
                                   struct image_params *imgp, uintptr_t stack);
static void     linux_exec_sysvec_init(void *param);
static int      linux_on_exec_vmspace(struct proc *p,
                    struct image_params *imgp);
static void     linux32_fixlimit(struct rlimit *rl, int which);
static void     linux_vdso_install(const void *param);
static void     linux_vdso_deinstall(const void *param);
static void     linux_vdso_reloc(char *mapping, Elf_Addr offset);
static void     linux32_set_fork_retval(struct thread *td);
static void     linux32_set_syscall_retval(struct thread *td, int error);

struct linux32_ps_strings {
        u_int32_t ps_argvstr;   /* first of 0 or more argument strings */
        u_int ps_nargvstr;      /* the number of argument strings */
        u_int32_t ps_envstr;    /* first of 0 or more environment strings */
        u_int ps_nenvstr;       /* the number of environment strings */
};
#define LINUX32_PS_STRINGS      (LINUX32_USRSTACK - \
                                    sizeof(struct linux32_ps_strings))

LINUX_VDSO_SYM_INTPTR(__kernel_vsyscall);
LINUX_VDSO_SYM_INTPTR(linux32_vdso_sigcode);
LINUX_VDSO_SYM_INTPTR(linux32_vdso_rt_sigcode);
LINUX_VDSO_SYM_INTPTR(kern_timekeep_base);
LINUX_VDSO_SYM_INTPTR(kern_tsc_selector);
LINUX_VDSO_SYM_INTPTR(kern_cpu_selector);
LINUX_VDSO_SYM_CHAR(linux_platform);

void
linux32_arch_copyout_auxargs(struct image_params *imgp, Elf_Auxinfo **pos)
{

        AUXARGS_ENTRY((*pos), LINUX_AT_SYSINFO, __kernel_vsyscall);
        AUXARGS_ENTRY((*pos), LINUX_AT_SYSINFO_EHDR, linux_vdso_base);
        AUXARGS_ENTRY((*pos), LINUX_AT_HWCAP, cpu_feature);
        AUXARGS_ENTRY((*pos), LINUX_AT_HWCAP2, linux_x86_elf_hwcap2());
        AUXARGS_ENTRY((*pos), LINUX_AT_PLATFORM, PTROUT(linux_platform));
}

static void
linux_rt_sendsig(sig_t catcher, ksiginfo_t *ksi, sigset_t *mask)
{
        struct thread *td = curthread;
        struct proc *p = td->td_proc;
        struct sigacts *psp;
        struct trapframe *regs;
        struct l_rt_sigframe *fp, frame;
        int oonstack;
        int sig;
        int code;

        sig = linux_translate_traps(ksi->ksi_signo, ksi->ksi_trapno);
        code = ksi->ksi_code;
        PROC_LOCK_ASSERT(p, MA_OWNED);
        psp = p->p_sigacts;
        mtx_assert(&psp->ps_mtx, MA_OWNED);
        regs = td->td_frame;
        oonstack = sigonstack(regs->tf_rsp);

        /* Allocate space for the signal handler context. */
        if ((td->td_pflags & TDP_ALTSTACK) && !oonstack &&
            SIGISMEMBER(psp->ps_sigonstack, sig)) {
                fp = (struct l_rt_sigframe *)((uintptr_t)td->td_sigstk.ss_sp +
                    td->td_sigstk.ss_size - sizeof(struct l_rt_sigframe));
        } else
                fp = (struct l_rt_sigframe *)regs->tf_rsp - 1;
        mtx_unlock(&psp->ps_mtx);

        /* Build the argument list for the signal handler. */
        sig = bsd_to_linux_signal(sig);

        bzero(&frame, sizeof(frame));

        frame.sf_sig = sig;
        frame.sf_siginfo = PTROUT(&fp->sf_si);
        frame.sf_ucontext = PTROUT(&fp->sf_uc);

        /* Fill in POSIX parts. */
        siginfo_to_lsiginfo(&ksi->ksi_info, &frame.sf_si, sig);

        /*
         * Build the signal context to be used by sigreturn and libgcc unwind.
         */
        frame.sf_uc.uc_stack.ss_sp = PTROUT(td->td_sigstk.ss_sp);
        frame.sf_uc.uc_stack.ss_size = td->td_sigstk.ss_size;
        frame.sf_uc.uc_stack.ss_flags = (td->td_pflags & TDP_ALTSTACK)
            ? ((oonstack) ? LINUX_SS_ONSTACK : 0) : LINUX_SS_DISABLE;
        PROC_UNLOCK(p);

        bsd_to_linux_sigset(mask, &frame.sf_uc.uc_sigmask);

        frame.sf_uc.uc_mcontext.sc_mask   = frame.sf_uc.uc_sigmask.__mask;
        frame.sf_uc.uc_mcontext.sc_edi    = regs->tf_rdi;
        frame.sf_uc.uc_mcontext.sc_esi    = regs->tf_rsi;
        frame.sf_uc.uc_mcontext.sc_ebp    = regs->tf_rbp;
        frame.sf_uc.uc_mcontext.sc_ebx    = regs->tf_rbx;
        frame.sf_uc.uc_mcontext.sc_esp    = regs->tf_rsp;
        frame.sf_uc.uc_mcontext.sc_edx    = regs->tf_rdx;
        frame.sf_uc.uc_mcontext.sc_ecx    = regs->tf_rcx;
        frame.sf_uc.uc_mcontext.sc_eax    = regs->tf_rax;
        frame.sf_uc.uc_mcontext.sc_eip    = regs->tf_rip;
        frame.sf_uc.uc_mcontext.sc_cs     = regs->tf_cs;
        frame.sf_uc.uc_mcontext.sc_gs     = regs->tf_gs;
        frame.sf_uc.uc_mcontext.sc_fs     = regs->tf_fs;
        frame.sf_uc.uc_mcontext.sc_es     = regs->tf_es;
        frame.sf_uc.uc_mcontext.sc_ds     = regs->tf_ds;
        frame.sf_uc.uc_mcontext.sc_eflags = regs->tf_rflags;
        frame.sf_uc.uc_mcontext.sc_esp_at_signal = regs->tf_rsp;
        frame.sf_uc.uc_mcontext.sc_ss     = regs->tf_ss;
        frame.sf_uc.uc_mcontext.sc_err    = regs->tf_err;
        frame.sf_uc.uc_mcontext.sc_cr2    = (u_int32_t)(uintptr_t)ksi->ksi_addr;
        frame.sf_uc.uc_mcontext.sc_trapno = bsd_to_linux_trapcode(code);

        if (copyout(&frame, fp, sizeof(frame)) != 0) {
                /*
                 * Process has trashed its stack; give it an illegal
                 * instruction to halt it in its tracks.
                 */
                PROC_LOCK(p);
                sigexit(td, SIGILL);
        }

        /* Build context to run handler in. */
        regs->tf_rsp = PTROUT(fp);
        regs->tf_rip = linux32_vdso_rt_sigcode;
        regs->tf_rdi = PTROUT(catcher);
        regs->tf_rflags &= ~(PSL_T | PSL_D);
        regs->tf_cs = _ucode32sel;
        regs->tf_ss = _udatasel;
        regs->tf_ds = _udatasel;
        regs->tf_es = _udatasel;
        regs->tf_fs = _ufssel;
        regs->tf_gs = _ugssel;
        regs->tf_flags = TF_HASSEGS;
        set_pcb_flags(td->td_pcb, PCB_FULL_IRET);
        PROC_LOCK(p);
        mtx_lock(&psp->ps_mtx);
}

/*
 * Send an interrupt to process.
 *
 * Stack is set up to allow sigcode stored
 * in u. to call routine, followed by kcall
 * to sigreturn routine below.  After sigreturn
 * resets the signal mask, the stack, and the
 * frame pointer, it returns to the user
 * specified pc, psl.
 */
static void
linux_sendsig(sig_t catcher, ksiginfo_t *ksi, sigset_t *mask)
{
        struct thread *td = curthread;
        struct proc *p = td->td_proc;
        struct sigacts *psp;
        struct trapframe *regs;
        struct l_sigframe *fp, frame;
        l_sigset_t lmask;
        int oonstack;
        int sig, code;

        sig = linux_translate_traps(ksi->ksi_signo, ksi->ksi_trapno);
        code = ksi->ksi_code;
        PROC_LOCK_ASSERT(p, MA_OWNED);
        psp = p->p_sigacts;
        mtx_assert(&psp->ps_mtx, MA_OWNED);
        if (SIGISMEMBER(psp->ps_siginfo, sig)) {
                /* Signal handler installed with SA_SIGINFO. */
                linux_rt_sendsig(catcher, ksi, mask);
                return;
        }

        regs = td->td_frame;
        oonstack = sigonstack(regs->tf_rsp);

        /* Allocate space for the signal handler context. */
        if ((td->td_pflags & TDP_ALTSTACK) && !oonstack &&
            SIGISMEMBER(psp->ps_sigonstack, sig)) {
                fp = (struct l_sigframe *)((uintptr_t)td->td_sigstk.ss_sp +
                    td->td_sigstk.ss_size - sizeof(struct l_sigframe));
        } else
                fp = (struct l_sigframe *)regs->tf_rsp - 1;
        mtx_unlock(&psp->ps_mtx);
        PROC_UNLOCK(p);

        /* Build the argument list for the signal handler. */
        sig = bsd_to_linux_signal(sig);

        bzero(&frame, sizeof(frame));

        frame.sf_sig = sig;
        frame.sf_sigmask = *mask;
        bsd_to_linux_sigset(mask, &lmask);

        /* Build the signal context to be used by sigreturn. */
        frame.sf_sc.sc_mask   = lmask.__mask;
        frame.sf_sc.sc_gs     = regs->tf_gs;
        frame.sf_sc.sc_fs     = regs->tf_fs;
        frame.sf_sc.sc_es     = regs->tf_es;
        frame.sf_sc.sc_ds     = regs->tf_ds;
        frame.sf_sc.sc_edi    = regs->tf_rdi;
        frame.sf_sc.sc_esi    = regs->tf_rsi;
        frame.sf_sc.sc_ebp    = regs->tf_rbp;
        frame.sf_sc.sc_ebx    = regs->tf_rbx;
        frame.sf_sc.sc_esp    = regs->tf_rsp;
        frame.sf_sc.sc_edx    = regs->tf_rdx;
        frame.sf_sc.sc_ecx    = regs->tf_rcx;
        frame.sf_sc.sc_eax    = regs->tf_rax;
        frame.sf_sc.sc_eip    = regs->tf_rip;
        frame.sf_sc.sc_cs     = regs->tf_cs;
        frame.sf_sc.sc_eflags = regs->tf_rflags;
        frame.sf_sc.sc_esp_at_signal = regs->tf_rsp;
        frame.sf_sc.sc_ss     = regs->tf_ss;
        frame.sf_sc.sc_err    = regs->tf_err;
        frame.sf_sc.sc_cr2    = (u_int32_t)(uintptr_t)ksi->ksi_addr;
        frame.sf_sc.sc_trapno = bsd_to_linux_trapcode(code);

        if (copyout(&frame, fp, sizeof(frame)) != 0) {
                /*
                 * Process has trashed its stack; give it an illegal
                 * instruction to halt it in its tracks.
                 */
                PROC_LOCK(p);
                sigexit(td, SIGILL);
        }

        /* Build context to run handler in. */
        regs->tf_rsp = PTROUT(fp);
        regs->tf_rip = linux32_vdso_sigcode;
        regs->tf_rdi = PTROUT(catcher);
        regs->tf_rflags &= ~(PSL_T | PSL_D);
        regs->tf_cs = _ucode32sel;
        regs->tf_ss = _udatasel;
        regs->tf_ds = _udatasel;
        regs->tf_es = _udatasel;
        regs->tf_fs = _ufssel;
        regs->tf_gs = _ugssel;
        regs->tf_flags = TF_HASSEGS;
        set_pcb_flags(td->td_pcb, PCB_FULL_IRET);
        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
 * psl to gain improper privileges or to cause
 * a machine fault.
 */
int
linux_sigreturn(struct thread *td, struct linux_sigreturn_args *args)
{
        struct l_sigframe frame;
        struct trapframe *regs;
        int eflags;
        ksiginfo_t ksi;

        regs = td->td_frame;

        /*
         * The trampoline code hands us the sigframe.
         * It is unsafe to keep track of it ourselves, in the event that a
         * program jumps out of a signal handler.
         */
        if (copyin(args->sfp, &frame, sizeof(frame)) != 0)
                return (EFAULT);

        /* Check for security violations. */
        eflags = frame.sf_sc.sc_eflags;
        if (!EFL_SECURE(eflags, regs->tf_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.
         */
        if (!CS_SECURE(frame.sf_sc.sc_cs)) {
                ksiginfo_init_trap(&ksi);
                ksi.ksi_signo = SIGBUS;
                ksi.ksi_code = BUS_OBJERR;
                ksi.ksi_trapno = T_PROTFLT;
                ksi.ksi_addr = (void *)regs->tf_rip;
                trapsignal(td, &ksi);
                return(EINVAL);
        }

        kern_sigprocmask(td, SIG_SETMASK, &frame.sf_sigmask, NULL, 0);

        /* Restore signal context. */
        regs->tf_rdi    = frame.sf_sc.sc_edi;
        regs->tf_rsi    = frame.sf_sc.sc_esi;
        regs->tf_rbp    = frame.sf_sc.sc_ebp;
        regs->tf_rbx    = frame.sf_sc.sc_ebx;
        regs->tf_rdx    = frame.sf_sc.sc_edx;
        regs->tf_rcx    = frame.sf_sc.sc_ecx;
        regs->tf_rax    = frame.sf_sc.sc_eax;
        regs->tf_rip    = frame.sf_sc.sc_eip;
        regs->tf_cs     = frame.sf_sc.sc_cs;
        regs->tf_ds     = frame.sf_sc.sc_ds;
        regs->tf_es     = frame.sf_sc.sc_es;
        regs->tf_fs     = frame.sf_sc.sc_fs;
        regs->tf_gs     = frame.sf_sc.sc_gs;
        regs->tf_rflags = eflags;
        regs->tf_rsp    = frame.sf_sc.sc_esp_at_signal;
        regs->tf_ss     = frame.sf_sc.sc_ss;
        set_pcb_flags(td->td_pcb, PCB_FULL_IRET);

        return (EJUSTRETURN);
}

/*
 * System call to cleanup state after a signal
 * has been taken.  Reset signal mask and
 * stack state from context left by rt_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
 * psl to gain improper privileges or to cause
 * a machine fault.
 */
int
linux_rt_sigreturn(struct thread *td, struct linux_rt_sigreturn_args *args)
{
        struct l_ucontext uc;
        struct l_sigcontext *context;
        sigset_t bmask;
        l_stack_t *lss;
        stack_t ss;
        struct trapframe *regs;
        int eflags;
        ksiginfo_t ksi;

        regs = td->td_frame;

        /*
         * The trampoline code hands us the ucontext.
         * It is unsafe to keep track of it ourselves, in the event that a
         * program jumps out of a signal handler.
         */
        if (copyin(args->ucp, &uc, sizeof(uc)) != 0)
                return (EFAULT);

        context = &uc.uc_mcontext;

        /* Check for security violations. */
        eflags = context->sc_eflags;
        if (!EFL_SECURE(eflags, regs->tf_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.
         */
        if (!CS_SECURE(context->sc_cs)) {
                ksiginfo_init_trap(&ksi);
                ksi.ksi_signo = SIGBUS;
                ksi.ksi_code = BUS_OBJERR;
                ksi.ksi_trapno = T_PROTFLT;
                ksi.ksi_addr = (void *)regs->tf_rip;
                trapsignal(td, &ksi);
                return(EINVAL);
        }

        linux_to_bsd_sigset(&uc.uc_sigmask, &bmask);
        kern_sigprocmask(td, SIG_SETMASK, &bmask, NULL, 0);

        /*
         * Restore signal context
         */
        regs->tf_gs     = context->sc_gs;
        regs->tf_fs     = context->sc_fs;
        regs->tf_es     = context->sc_es;
        regs->tf_ds     = context->sc_ds;
        regs->tf_rdi    = context->sc_edi;
        regs->tf_rsi    = context->sc_esi;
        regs->tf_rbp    = context->sc_ebp;
        regs->tf_rbx    = context->sc_ebx;
        regs->tf_rdx    = context->sc_edx;
        regs->tf_rcx    = context->sc_ecx;
        regs->tf_rax    = context->sc_eax;
        regs->tf_rip    = context->sc_eip;
        regs->tf_cs     = context->sc_cs;
        regs->tf_rflags = eflags;
        regs->tf_rsp    = context->sc_esp_at_signal;
        regs->tf_ss     = context->sc_ss;
        set_pcb_flags(td->td_pcb, PCB_FULL_IRET);

        /*
         * call sigaltstack & ignore results..
         */
        lss = &uc.uc_stack;
        ss.ss_sp = PTRIN(lss->ss_sp);
        ss.ss_size = lss->ss_size;
        ss.ss_flags = linux_to_bsd_sigaltstack(lss->ss_flags);

        (void)kern_sigaltstack(td, &ss, NULL);

        return (EJUSTRETURN);
}

static int
linux32_fetch_syscall_args(struct thread *td)
{
        struct proc *p;
        struct trapframe *frame;
        struct syscall_args *sa;

        p = td->td_proc;
        frame = td->td_frame;
        sa = &td->td_sa;

        sa->args[0] = frame->tf_rbx;
        sa->args[1] = frame->tf_rcx;
        sa->args[2] = frame->tf_rdx;
        sa->args[3] = frame->tf_rsi;
        sa->args[4] = frame->tf_rdi;
        sa->args[5] = frame->tf_rbp;
        sa->code = frame->tf_rax;
        sa->original_code = sa->code;

        if (sa->code >= p->p_sysent->sv_size)
                /* nosys */
                sa->callp = &nosys_sysent;
        else
                sa->callp = &p->p_sysent->sv_table[sa->code];

        td->td_retval[0] = 0;
        td->td_retval[1] = frame->tf_rdx;

        return (0);
}

static void
linux32_set_syscall_retval(struct thread *td, int error)
{
        struct trapframe *frame = td->td_frame;

        cpu_set_syscall_retval(td, error);

        if (__predict_false(error != 0)) {
                if (error != ERESTART && error != EJUSTRETURN)
                        frame->tf_rax = bsd_to_linux_errno(error);
        }
}

static void
linux32_set_fork_retval(struct thread *td)
{
        struct trapframe *frame = td->td_frame;

        frame->tf_rax = 0;
}

/*
 * Clear registers on exec
 * XXX copied from ia32_signal.c.
 */
static void
linux_exec_setregs(struct thread *td, struct image_params *imgp,
    uintptr_t stack)
{
        struct trapframe *regs = td->td_frame;
        struct pcb *pcb = td->td_pcb;
        register_t saved_rflags;

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

        if (td->td_proc->p_md.md_ldt != NULL)
                user_ldt_free(td);

        /* Do full restore on return so that we can change to a different %cs */
        set_pcb_flags(pcb, PCB_32BIT | PCB_FULL_IRET);
        clear_pcb_flags(pcb, PCB_TLSBASE);

        critical_enter();
        wrmsr(MSR_FSBASE, 0);
        wrmsr(MSR_KGSBASE, 0);  /* User value while we're in the kernel */
        pcb->pcb_fsbase = 0;
        pcb->pcb_gsbase = 0;
        critical_exit();
        pcb->pcb_initial_fpucw = __LINUX_NPXCW__;

        saved_rflags = regs->tf_rflags & PSL_T;
        bzero((char *)regs, sizeof(struct trapframe));
        regs->tf_rip = imgp->entry_addr;
        regs->tf_rsp = stack;
        regs->tf_rflags = PSL_USER | saved_rflags;
        regs->tf_gs = _ugssel;
        regs->tf_fs = _ufssel;
        regs->tf_es = _udatasel;
        regs->tf_ds = _udatasel;
        regs->tf_ss = _udatasel;
        regs->tf_flags = TF_HASSEGS;
        regs->tf_cs = _ucode32sel;
        regs->tf_rbx = (register_t)imgp->ps_strings;

        x86_clear_dbregs(pcb);

        fpstate_drop(td);
}

/*
 * XXX copied from ia32_sysvec.c.
 */
static int
linux_copyout_strings(struct image_params *imgp, uintptr_t *stack_base)
{
        int argc, envc, error;
        u_int32_t *vectp;
        char *stringp;
        uintptr_t destp, ustringp;
        struct linux32_ps_strings *arginfo;
        char canary[LINUX_AT_RANDOM_LEN];
        size_t execpath_len;

        arginfo = (struct linux32_ps_strings *)PROC_PS_STRINGS(imgp->proc);
        destp = (uintptr_t)arginfo;

        if (imgp->execpath != NULL && imgp->auxargs != NULL) {
                execpath_len = strlen(imgp->execpath) + 1;
                destp -= execpath_len;
                destp = rounddown2(destp, sizeof(uint32_t));
                imgp->execpathp = (void *)destp;
                error = copyout(imgp->execpath, imgp->execpathp, execpath_len);
                if (error != 0)
                        return (error);
        }

        /* Prepare the canary for SSP. */
        arc4rand(canary, sizeof(canary), 0);
        destp -= roundup(sizeof(canary), sizeof(uint32_t));
        imgp->canary = (void *)destp;
        error = copyout(canary, imgp->canary, sizeof(canary));
        if (error != 0)
                return (error);

        /* Allocate room for the argument and environment strings. */
        destp -= ARG_MAX - imgp->args->stringspace;
        destp = rounddown2(destp, sizeof(uint32_t));
        ustringp = destp;

        if (imgp->auxargs) {
                /*
                 * Allocate room on the stack for the ELF auxargs
                 * array.  It has LINUX_AT_COUNT entries.
                 */
                destp -= LINUX_AT_COUNT * sizeof(Elf32_Auxinfo);
                destp = rounddown2(destp, sizeof(uint32_t));
        }

        vectp = (uint32_t *)destp;

        /*
         * Allocate room for the argv[] and env vectors including the
         * terminating NULL pointers.
         */
        vectp -= imgp->args->argc + 1 + imgp->args->envc + 1;

        /* vectp also becomes our initial stack base. */
        *stack_base = (uintptr_t)vectp;

        stringp = imgp->args->begin_argv;
        argc = imgp->args->argc;
        envc = imgp->args->envc;

        /* Copy out strings - arguments and environment. */
        error = copyout(stringp, (void *)ustringp,
            ARG_MAX - imgp->args->stringspace);
        if (error != 0)
                return (error);

        /* Fill in "ps_strings" struct for ps, w, etc. */
        if (suword32(&arginfo->ps_argvstr, (uint32_t)(intptr_t)vectp) != 0 ||
            suword32(&arginfo->ps_nargvstr, argc) != 0)
                return (EFAULT);

        /* Fill in argument portion of vector table. */
        for (; argc > 0; --argc) {
                if (suword32(vectp++, ustringp) != 0)
                        return (EFAULT);
                while (*stringp++ != 0)
                        ustringp++;
                ustringp++;
        }

        /* A null vector table pointer separates the argp's from the envp's. */
        if (suword32(vectp++, 0) != 0)
                return (EFAULT);

        if (suword32(&arginfo->ps_envstr, (uint32_t)(intptr_t)vectp) != 0 ||
            suword32(&arginfo->ps_nenvstr, envc) != 0)
                return (EFAULT);

        /* Fill in environment portion of vector table. */
        for (; envc > 0; --envc) {
                if (suword32(vectp++, ustringp) != 0)
                        return (EFAULT);
                while (*stringp++ != 0)
                        ustringp++;
                ustringp++;
        }

        /* The end of the vector table is a null pointer. */
        if (suword32(vectp, 0) != 0)
                return (EFAULT);

        if (imgp->auxargs) {
                vectp++;
                error = imgp->sysent->sv_copyout_auxargs(imgp,
                    (uintptr_t)vectp);
                if (error != 0)
                        return (error);
        }

        return (0);
}

static SYSCTL_NODE(_compat, OID_AUTO, linux32, CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
    "32-bit Linux emulation");

static u_long   linux32_maxdsiz = LINUX32_MAXDSIZ;
SYSCTL_ULONG(_compat_linux32, OID_AUTO, maxdsiz, CTLFLAG_RW,
    &linux32_maxdsiz, 0, "");
static u_long   linux32_maxssiz = LINUX32_MAXSSIZ;
SYSCTL_ULONG(_compat_linux32, OID_AUTO, maxssiz, CTLFLAG_RW,
    &linux32_maxssiz, 0, "");
static u_long   linux32_maxvmem = LINUX32_MAXVMEM;
SYSCTL_ULONG(_compat_linux32, OID_AUTO, maxvmem, CTLFLAG_RW,
    &linux32_maxvmem, 0, "");
bool linux32_emulate_i386 = false;
SYSCTL_BOOL(_compat_linux32, OID_AUTO, emulate_i386, CTLFLAG_RWTUN,
    &linux32_emulate_i386, 0, "Emulate the real i386");

static void
linux32_fixlimit(struct rlimit *rl, int which)
{

        switch (which) {
        case RLIMIT_DATA:
                if (linux32_maxdsiz != 0) {
                        if (rl->rlim_cur > linux32_maxdsiz)
                                rl->rlim_cur = linux32_maxdsiz;
                        if (rl->rlim_max > linux32_maxdsiz)
                                rl->rlim_max = linux32_maxdsiz;
                }
                break;
        case RLIMIT_STACK:
                if (linux32_maxssiz != 0) {
                        if (rl->rlim_cur > linux32_maxssiz)
                                rl->rlim_cur = linux32_maxssiz;
                        if (rl->rlim_max > linux32_maxssiz)
                                rl->rlim_max = linux32_maxssiz;
                }
                break;
        case RLIMIT_VMEM:
                if (linux32_maxvmem != 0) {
                        if (rl->rlim_cur > linux32_maxvmem)
                                rl->rlim_cur = linux32_maxvmem;
                        if (rl->rlim_max > linux32_maxvmem)
                                rl->rlim_max = linux32_maxvmem;
                }
                break;
        }
}

struct sysentvec elf_linux_sysvec = {
        .sv_size        = LINUX32_SYS_MAXSYSCALL,
        .sv_table       = linux32_sysent,
        .sv_fixup       = elf32_freebsd_fixup,
        .sv_sendsig     = linux_sendsig,
        .sv_sigcode     = &_binary_linux32_vdso_so_o_start,
        .sv_szsigcode   = &linux_szsigcode,
        .sv_name        = "Linux ELF32",
        .sv_coredump    = elf32_coredump,
        .sv_elf_core_osabi = ELFOSABI_NONE,
        .sv_elf_core_abi_vendor = LINUX_ABI_VENDOR,
        .sv_elf_core_prepare_notes = linux32_prepare_notes,
        .sv_minsigstksz = LINUX_MINSIGSTKSZ,
        .sv_minuser     = VM_MIN_ADDRESS,
        .sv_maxuser     = LINUX32_MAXUSER,
        .sv_usrstack    = LINUX32_USRSTACK,
        .sv_psstrings   = LINUX32_PS_STRINGS,
        .sv_psstringssz = sizeof(struct linux32_ps_strings),
        .sv_stackprot   = VM_PROT_ALL,
        .sv_copyout_auxargs = __linuxN(copyout_auxargs),
        .sv_copyout_strings = linux_copyout_strings,
        .sv_setregs     = linux_exec_setregs,
        .sv_fixlimit    = linux32_fixlimit,
        .sv_maxssiz     = &linux32_maxssiz,
        .sv_flags       = SV_ABI_LINUX | SV_ILP32 | SV_SHP |
            SV_SIG_DISCIGN | SV_SIG_WAITNDQ | SV_TIMEKEEP,
        .sv_set_syscall_retval = linux32_set_syscall_retval,
        .sv_fetch_syscall_args = linux32_fetch_syscall_args,
        .sv_syscallnames = linux32_syscallnames,
        .sv_shared_page_base = LINUX32_SHAREDPAGE,
        .sv_shared_page_len = PAGE_SIZE,
        .sv_schedtail   = linux_schedtail,
        .sv_thread_detach = linux_thread_detach,
        .sv_trap        = NULL,
        .sv_hwcap       = NULL,
        .sv_hwcap2      = NULL,
        .sv_hwcap3      = NULL,
        .sv_hwcap4      = NULL,
        .sv_onexec      = linux_on_exec_vmspace,
        .sv_onexit      = linux_on_exit,
        .sv_ontdexit    = linux_thread_dtor,
        .sv_setid_allowed = &linux_setid_allowed_query,
        .sv_set_fork_retval = linux32_set_fork_retval,
};

static int
linux_on_exec_vmspace(struct proc *p, struct image_params *imgp)
{
        int error;

        error = linux_map_vdso(p, linux_vdso_obj, linux_vdso_base,
            LINUX32_VDSOPAGE_SIZE, imgp);
        if (error == 0)
                error = linux_on_exec(p, imgp);
        return (error);
}

/*
 * linux_vdso_install() and linux_exec_sysvec_init() must be called
 * after exec_sysvec_init() which is SI_SUB_EXEC (SI_ORDER_ANY).
 */
static void
linux_exec_sysvec_init(void *param)
{
        l_uintptr_t *ktimekeep_base, *ktsc_selector;
        struct sysentvec *sv;
        ptrdiff_t tkoff;

        sv = param;
        /* Fill timekeep_base */
        exec_sysvec_init(sv);

        tkoff = kern_timekeep_base - linux_vdso_base;
        ktimekeep_base = (l_uintptr_t *)(linux_vdso_mapping + tkoff);
        *ktimekeep_base = sv->sv_shared_page_base + sv->sv_timekeep_offset;

        tkoff = kern_tsc_selector - linux_vdso_base;
        ktsc_selector = (l_uintptr_t *)(linux_vdso_mapping + tkoff);
        *ktsc_selector = linux_vdso_tsc_selector_idx();
        if (bootverbose)
                printf("Linux i386 vDSO tsc_selector: %u\n", *ktsc_selector);

        tkoff = kern_cpu_selector - linux_vdso_base;
        ktsc_selector = (l_uintptr_t *)(linux_vdso_mapping + tkoff);
        *ktsc_selector = linux_vdso_cpu_selector_idx();
        if (bootverbose)
                printf("Linux i386 vDSO cpu_selector: %u\n", *ktsc_selector);
}
SYSINIT(elf_linux_exec_sysvec_init, SI_SUB_EXEC + 1, SI_ORDER_ANY,
    linux_exec_sysvec_init, &elf_linux_sysvec);

static void
linux_vdso_install(const void *param)
{
        char *vdso_start = &_binary_linux32_vdso_so_o_start;
        char *vdso_end = &_binary_linux32_vdso_so_o_end;

        linux_szsigcode = vdso_end - vdso_start;
        MPASS(linux_szsigcode <= LINUX32_VDSOPAGE_SIZE);

        linux_vdso_base = LINUX32_VDSOPAGE;

        __elfN(linux_vdso_fixup)(vdso_start, linux_vdso_base);

        linux_vdso_obj = __elfN(linux_shared_page_init)
            (&linux_vdso_mapping, LINUX32_VDSOPAGE_SIZE);
        bcopy(vdso_start, linux_vdso_mapping, linux_szsigcode);

        linux_vdso_reloc(linux_vdso_mapping, linux_vdso_base);
}
SYSINIT(elf_linux_vdso_init, SI_SUB_EXEC + 1, SI_ORDER_FIRST,
    linux_vdso_install, NULL);

static void
linux_vdso_deinstall(const void *param)
{

        __elfN(linux_shared_page_fini)(linux_vdso_obj,
            linux_vdso_mapping, LINUX32_VDSOPAGE_SIZE);
}
SYSUNINIT(elf_linux_vdso_uninit, SI_SUB_EXEC, SI_ORDER_FIRST,
    linux_vdso_deinstall, NULL);

static void
linux_vdso_reloc(char *mapping, Elf_Addr offset)
{
        const Elf_Shdr *shdr;
        const Elf_Rel *rel;
        const Elf_Ehdr *ehdr;
        Elf32_Addr *where;
        Elf_Size rtype, symidx;
        Elf32_Addr addr, addend;
        int i, relcnt;

        MPASS(offset != 0);

        relcnt = 0;
        ehdr = (const Elf_Ehdr *)mapping;
        shdr = (const Elf_Shdr *)(mapping + ehdr->e_shoff);
        for (i = 0; i < ehdr->e_shnum; i++)
        {
                switch (shdr[i].sh_type) {
                case SHT_REL:
                        rel = (const Elf_Rel *)(mapping + shdr[i].sh_offset);
                        relcnt = shdr[i].sh_size / sizeof(*rel);
                        break;
                case SHT_RELA:
                        printf("Linux i386 vDSO: unexpected Rela section\n");
                        break;
                }
        }

        for (i = 0; i < relcnt; i++, rel++) {
                where = (Elf32_Addr *)(mapping + rel->r_offset);
                addend = *where;
                rtype = ELF_R_TYPE(rel->r_info);
                symidx = ELF_R_SYM(rel->r_info);

                switch (rtype) {
                case R_386_NONE:        /* none */
                        break;

                case R_386_RELATIVE:    /* B + A */
                        addr = (Elf32_Addr)PTROUT(offset + addend);
                        if (*where != addr)
                                *where = addr;
                        break;

                case R_386_IRELATIVE:
                        printf("Linux i386 vDSO: unexpected ifunc relocation, "
                            "symbol index %ld\n", (intmax_t)symidx);
                        break;
                default:
                        printf("Linux i386 vDSO: unexpected relocation type %ld, "
                            "symbol index %ld\n", (intmax_t)rtype, (intmax_t)symidx);
                }
        }
}

static const Elf_Brandnote linux32_brandnote = {
        .hdr.n_namesz   = sizeof(GNU_ABI_VENDOR),
        .hdr.n_descsz   = 16,   /* XXX at least 16 */
        .hdr.n_type     = 1,
        .vendor         = GNU_ABI_VENDOR,
        .flags          = BN_TRANSLATE_OSREL,
        .trans_osrel    = linux_trans_osrel
};

static const Elf32_Brandinfo linux_brand = {
        .brand          = ELFOSABI_LINUX,
        .machine        = EM_386,
        .compat_3_brand = "Linux",
        .interp_path    = "/lib/ld-linux.so.1",
        .sysvec         = &elf_linux_sysvec,
        .interp_newpath = NULL,
        .brand_note     = &linux32_brandnote,
        .flags          = BI_CAN_EXEC_DYN | BI_BRAND_NOTE
};

static const Elf32_Brandinfo linux_glibc2brand = {
        .brand          = ELFOSABI_LINUX,
        .machine        = EM_386,
        .compat_3_brand = "Linux",
        .interp_path    = "/lib/ld-linux.so.2",
        .sysvec         = &elf_linux_sysvec,
        .interp_newpath = NULL,
        .brand_note     = &linux32_brandnote,
        .flags          = BI_CAN_EXEC_DYN | BI_BRAND_NOTE
};

static const Elf32_Brandinfo linux_muslbrand = {
        .brand          = ELFOSABI_LINUX,
        .machine        = EM_386,
        .compat_3_brand = "Linux",
        .interp_path    = "/lib/ld-musl-i386.so.1",
        .sysvec         = &elf_linux_sysvec,
        .interp_newpath = NULL,
        .brand_note     = &linux32_brandnote,
        .flags          = BI_CAN_EXEC_DYN | BI_BRAND_NOTE |
                            LINUX_BI_FUTEX_REQUEUE
};

static const Elf32_Brandinfo *linux_brandlist[] = {
        &linux_brand,
        &linux_glibc2brand,
        &linux_muslbrand,
        NULL
};

static int
linux_elf_modevent(module_t mod, int type, void *data)
{
        const Elf32_Brandinfo **brandinfo;
        int error;
        struct linux_ioctl_handler **lihp;

        error = 0;

        switch(type) {
        case MOD_LOAD:
                for (brandinfo = &linux_brandlist[0]; *brandinfo != NULL;
                     ++brandinfo)
                        if (elf32_insert_brand_entry(*brandinfo) < 0)
                                error = EINVAL;
                if (error == 0) {
                        SET_FOREACH(lihp, linux_ioctl_handler_set)
                                linux32_ioctl_register_handler(*lihp);
                        stclohz = (stathz ? stathz : hz);
                        if (bootverbose)
                                printf("Linux i386 ELF exec handler installed\n");
                } else
                        printf("cannot insert Linux i386 ELF brand handler\n");
                break;
        case MOD_UNLOAD:
                for (brandinfo = &linux_brandlist[0]; *brandinfo != NULL;
                     ++brandinfo)
                        if (elf32_brand_inuse(*brandinfo))
                                error = EBUSY;
                if (error == 0) {
                        for (brandinfo = &linux_brandlist[0];
                             *brandinfo != NULL; ++brandinfo)
                                if (elf32_remove_brand_entry(*brandinfo) < 0)
                                        error = EINVAL;
                }
                if (error == 0) {
                        SET_FOREACH(lihp, linux_ioctl_handler_set)
                                linux32_ioctl_unregister_handler(*lihp);
                        if (bootverbose)
                                printf("Linux i386 ELF exec handler removed\n");
                } else
                        printf("Could not deinstall Linux i386 ELF interpreter entry\n");
                break;
        default:
                return (EOPNOTSUPP);
        }
        return (error);
}

static moduledata_t linux_elf_mod = {
        "linuxelf",
        linux_elf_modevent,
        0
};

DECLARE_MODULE_TIED(linuxelf, linux_elf_mod, SI_SUB_EXEC, SI_ORDER_ANY);
MODULE_DEPEND(linuxelf, linux_common, 1, 1, 1);
FEATURE(linux, "Linux 32bit support");