/*-
 * 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.
 * Copyright (c) 2013, 2021 Dmitry Chagin <dchagin@FreeBSD.org>
 *
 * 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.
 */

#define __ELF_WORD_SIZE 64

#include <sys/param.h>
#include <sys/exec.h>
#include <sys/imgact.h>
#include <sys/imgact_elf.h>
#include <sys/kernel.h>
#include <sys/ktr.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_param.h>

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

#include <x86/linux/linux_x86.h>
#include <amd64/linux/linux.h>
#include <amd64/linux/linux_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>

_Static_assert(sizeof(struct l_fpstate) ==
    sizeof(__typeof(((mcontext_t *)0)->mc_fpstate)),
    "fxsave area size incorrect");

MODULE_VERSION(linux64, 1);

#define LINUX_VDSOPAGE_SIZE     PAGE_SIZE * 2
#define LINUX_VDSOPAGE_LA48     (VM_MAXUSER_ADDRESS_LA48 - \
                                    LINUX_VDSOPAGE_SIZE)
#define LINUX_SHAREDPAGE_LA48   (LINUX_VDSOPAGE_LA48 - PAGE_SIZE)
                                /*
                                 * PAGE_SIZE - the size
                                 * of the native SHAREDPAGE
                                 */
#define LINUX_USRSTACK_LA48     LINUX_SHAREDPAGE_LA48
#define LINUX_PS_STRINGS_LA48   (LINUX_USRSTACK_LA48 - \
                                    sizeof(struct ps_strings))

static int linux_szsigcode;
static vm_object_t linux_vdso_obj;
static char *linux_vdso_mapping;
extern char _binary_linux_vdso_so_o_start;
extern char _binary_linux_vdso_so_o_end;
static vm_offset_t linux_vdso_base;

extern struct sysent linux_sysent[LINUX_SYS_MAXSYSCALL];
extern const char *linux_syscallnames[];

SET_DECLARE(linux_ioctl_handler_set, struct linux_ioctl_handler);

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     linux_set_syscall_retval(struct thread *td, int error);
static int      linux_fetch_syscall_args(struct thread *td);
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     linux_set_fork_retval(struct thread *td);
static int      linux_vsyscall(struct thread *td);

LINUX_VDSO_SYM_INTPTR(linux_rt_sigcode);
LINUX_VDSO_SYM_CHAR(linux_platform);
LINUX_VDSO_SYM_INTPTR(kern_timekeep_base);
LINUX_VDSO_SYM_INTPTR(kern_tsc_selector);
LINUX_VDSO_SYM_INTPTR(kern_cpu_selector);

/*
 * According to the Intel x86 ISA 64-bit syscall
 * saves %rip to %rcx and rflags to %r11. Registers on syscall entry:
 * %rax  system call number
 * %rcx  return address
 * %r11  saved rflags
 * %rdi  arg1
 * %rsi  arg2
 * %rdx  arg3
 * %r10  arg4
 * %r8   arg5
 * %r9   arg6
 *
 * Then FreeBSD fast_syscall() move registers:
 * %rcx -> trapframe.tf_rip
 * %r10 -> trapframe.tf_rcx
 */
static int
linux_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_rdi;
        sa->args[1] = frame->tf_rsi;
        sa->args[2] = frame->tf_rdx;
        sa->args[3] = frame->tf_rcx;
        sa->args[4] = frame->tf_r8;
        sa->args[5] = frame->tf_r9;
        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];

        /* Restore r10 earlier to avoid doing this multiply times. */
        frame->tf_r10 = frame->tf_rcx;
        /* Restore %rcx for machine context. */
        frame->tf_rcx = frame->tf_rip;

        td->td_retval[0] = 0;
        return (0);
}

static void
linux_set_syscall_retval(struct thread *td, int error)
{
        struct trapframe *frame;

        frame = td->td_frame;

        switch (error) {
        case 0:
                frame->tf_rax = td->td_retval[0];
                break;

        case ERESTART:
                /*
                 * Reconstruct pc, we know that 'syscall' is 2 bytes,
                 * lcall $X,y is 7 bytes, int 0x80 is 2 bytes.
                 * We saved this in tf_err.
                 *
                 */
                frame->tf_rip -= frame->tf_err;
                break;

        case EJUSTRETURN:
                break;

        default:
                frame->tf_rax = bsd_to_linux_errno(error);
                break;
        }

        /*
         * Differently from FreeBSD native ABI, on Linux only %rcx
         * and %r11 values are not preserved across the syscall.
         * Require full context restore to get all registers except
         * those two restored at return to usermode.
         */
        set_pcb_flags(td->td_pcb, PCB_FULL_IRET);
}

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

        frame->tf_rax = 0;
}

void
linux64_arch_copyout_auxargs(struct image_params *imgp, Elf_Auxinfo **pos)
{

        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));
}

/*
 * Reset registers to default values on exec.
 */
static void
linux_exec_setregs(struct thread *td, struct image_params *imgp,
    uintptr_t stack)
{
        struct trapframe *regs;
        struct pcb *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);

        pcb->pcb_fsbase = 0;
        pcb->pcb_gsbase = 0;
        clear_pcb_flags(pcb, PCB_32BIT | PCB_TLSBASE);
        pcb->pcb_initial_fpucw = __LINUX_NPXCW__;
        set_pcb_flags(pcb, PCB_FULL_IRET);

        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_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;

        x86_clear_dbregs(pcb);

        /*
         * 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);
}

static int
linux_fxrstor(struct thread *td, mcontext_t *mcp, struct l_sigcontext *sc)
{
        struct savefpu *fp = (struct savefpu *)&mcp->mc_fpstate[0];
        int error;

        error = copyin(PTRIN(sc->sc_fpstate), fp, sizeof(mcp->mc_fpstate));
        if (error != 0)
                return (error);
        bzero(&fp->sv_pad[0], sizeof(fp->sv_pad));
        return (set_fpcontext(td, mcp, NULL, 0));
}

static int
linux_xrstor(struct thread *td, mcontext_t *mcp, struct l_sigcontext *sc)
{
        struct savefpu *fp = (struct savefpu *)&mcp->mc_fpstate[0];
        char *xfpustate;
        struct proc *p;
        uint32_t magic2;
        int error;

        p = td->td_proc;
        mcp->mc_xfpustate_len = cpu_max_ext_state_size - sizeof(struct savefpu);

        /* Legacy region of an xsave area. */
        error = copyin(PTRIN(sc->sc_fpstate), fp, sizeof(mcp->mc_fpstate));
        if (error != 0)
                return (error);
        bzero(&fp->sv_pad[0], sizeof(fp->sv_pad));

        /* Extended region of an xsave area. */
        sc->sc_fpstate += sizeof(mcp->mc_fpstate);
        xfpustate = (char *)fpu_save_area_alloc();
        error = copyin(PTRIN(sc->sc_fpstate), xfpustate, mcp->mc_xfpustate_len);
        if (error != 0) {
                fpu_save_area_free((struct savefpu *)xfpustate);
                uprintf("pid %d (%s): linux xrstor failed\n", p->p_pid,
                    td->td_name);
                return (error);
        }

        /* Linux specific end of xsave area marker. */
        sc->sc_fpstate += mcp->mc_xfpustate_len;
        error = copyin(PTRIN(sc->sc_fpstate), &magic2, LINUX_FP_XSTATE_MAGIC2_SIZE);
        if (error != 0 || magic2 != LINUX_FP_XSTATE_MAGIC2) {
                fpu_save_area_free((struct savefpu *)xfpustate);
                uprintf("pid %d (%s): sigreturn magic2 0x%x error %d\n",
                    p->p_pid, td->td_name, magic2, error);
                return (error);
        }

        error = set_fpcontext(td, mcp, xfpustate, mcp->mc_xfpustate_len);
        fpu_save_area_free((struct savefpu *)xfpustate);
        if (error != 0) {
                uprintf("pid %d (%s): sigreturn set_fpcontext error %d\n",
                    p->p_pid, td->td_name, error);
        }
        return (error);
}

static int
linux_copyin_fpstate(struct thread *td, struct l_ucontext *uc)
{
        mcontext_t mc;

        bzero(&mc, sizeof(mc));
        mc.mc_ownedfp = _MC_FPOWNED_FPU;
        mc.mc_fpformat = _MC_FPFMT_XMM;

        if ((uc->uc_flags & LINUX_UC_FP_XSTATE) != 0)
                return (linux_xrstor(td, &mc, &uc->uc_mcontext));
        else
                return (linux_fxrstor(td, &mc, &uc->uc_mcontext));
}

/*
 * Copied from amd64/amd64/machdep.c
 */
int
linux_rt_sigreturn(struct thread *td, struct linux_rt_sigreturn_args *args)
{
        struct proc *p;
        struct l_rt_sigframe sf;
        struct l_sigcontext *context;
        struct trapframe *regs;
        unsigned long rflags;
        sigset_t bmask;
        int error;
        ksiginfo_t ksi;

        regs = td->td_frame;
        error = copyin((void *)regs->tf_rbx, &sf, sizeof(sf));
        if (error != 0)
                return (error);

        p = td->td_proc;
        context = &sf.sf_uc.uc_mcontext;
        rflags = context->sc_rflags;

        /*
         * Don't allow users to change privileged or reserved flags.
         */
        /*
         * XXX do allow users to change the privileged flag PSL_RF.
         * The cpu sets PSL_RF in tf_rflags for faults.  Debuggers
         * should sometimes set it there too.  tf_rflags is kept in
         * the signal context during signal handling and there is no
         * other place to remember it, so the PSL_RF bit may be
         * corrupted by the signal handler without us knowing.
         * Corruption of the PSL_RF bit at worst causes one more or
         * one less debugger trap, so allowing it is fairly harmless.
         */
        if (!EFL_SECURE(rflags & ~PSL_RF, regs->tf_rflags & ~PSL_RF)) {
                uprintf("pid %d comm %s linux mangled rflags %#lx\n",
                    p->p_pid, p->p_comm, 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)) {
                uprintf("pid %d comm %s linux mangled cs %#x\n",
                    p->p_pid, p->p_comm, 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(&sf.sf_uc.uc_sigmask, &bmask);
        kern_sigprocmask(td, SIG_SETMASK, &bmask, NULL, 0);

        regs->tf_rdi    = context->sc_rdi;
        regs->tf_rsi    = context->sc_rsi;
        regs->tf_rdx    = context->sc_rdx;
        regs->tf_rbp    = context->sc_rbp;
        regs->tf_rbx    = context->sc_rbx;
        regs->tf_rcx    = context->sc_rcx;
        regs->tf_rax    = context->sc_rax;
        regs->tf_rip    = context->sc_rip;
        regs->tf_rsp    = context->sc_rsp;
        regs->tf_r8     = context->sc_r8;
        regs->tf_r9     = context->sc_r9;
        regs->tf_r10    = context->sc_r10;
        regs->tf_r11    = context->sc_r11;
        regs->tf_r12    = context->sc_r12;
        regs->tf_r13    = context->sc_r13;
        regs->tf_r14    = context->sc_r14;
        regs->tf_r15    = context->sc_r15;
        regs->tf_cs     = context->sc_cs;
        regs->tf_err    = context->sc_err;
        regs->tf_rflags = rflags;

        error = linux_copyin_fpstate(td, &sf.sf_uc);
        if (error != 0) {
                uprintf("pid %d comm %s linux can't restore fpu state %d\n",
                    p->p_pid, p->p_comm, error);
                return (error);
        }

        set_pcb_flags(td->td_pcb, PCB_FULL_IRET);
        return (EJUSTRETURN);
}

static int
linux_fxsave(mcontext_t *mcp, void *ufp)
{
        struct l_fpstate *fx = (struct l_fpstate *)&mcp->mc_fpstate[0];

        bzero(&fx->reserved2[0], sizeof(fx->reserved2));
        return (copyout(fx, ufp, sizeof(*fx)));
}

static int
linux_xsave(mcontext_t *mcp, char *xfpusave, char *ufp)
{
        struct l_fpstate *fx = (struct l_fpstate *)&mcp->mc_fpstate[0];
        uint32_t magic2;
        int error;

        /* Legacy region of an xsave area. */
        fx->sw_reserved.magic1 = LINUX_FP_XSTATE_MAGIC1;
        fx->sw_reserved.xstate_size = mcp->mc_xfpustate_len + sizeof(*fx);
        fx->sw_reserved.extended_size = fx->sw_reserved.xstate_size +
            LINUX_FP_XSTATE_MAGIC2_SIZE;
        fx->sw_reserved.xfeatures = xsave_mask;

        error = copyout(fx, ufp, sizeof(*fx));
        if (error != 0)
                return (error);
        ufp += sizeof(*fx);

        /* Extended region of an xsave area. */
        error = copyout(xfpusave, ufp, mcp->mc_xfpustate_len);
        if (error != 0)
                return (error);

        /* Linux specific end of xsave area marker. */
        ufp += mcp->mc_xfpustate_len;
        magic2 = LINUX_FP_XSTATE_MAGIC2;
        return (copyout(&magic2, ufp, LINUX_FP_XSTATE_MAGIC2_SIZE));
}

static int
linux_copyout_fpstate(struct thread *td, struct l_ucontext *uc, char **sp)
{
        size_t xfpusave_len;
        char *xfpusave;
        mcontext_t mc;
        char *ufp = *sp;

        get_fpcontext(td, &mc, &xfpusave, &xfpusave_len);
        KASSERT(mc.mc_fpformat != _MC_FPFMT_NODEV, ("fpu not present"));

        /* Room for fxsave area. */
        ufp -= sizeof(struct l_fpstate);
        if (xfpusave != NULL) {
                /* Room for xsave area. */
                ufp -= (xfpusave_len + LINUX_FP_XSTATE_MAGIC2_SIZE);
                uc->uc_flags |= LINUX_UC_FP_XSTATE;
        }
        *sp = ufp = (char *)((unsigned long)ufp & ~0x3Ful);

        if (xfpusave != NULL)
                return (linux_xsave(&mc, xfpusave, ufp));
        else
                return (linux_fxsave(&mc, ufp));
}

/*
 * copied from amd64/amd64/machdep.c
 *
 * Send an interrupt to process.
 */
static void
linux_rt_sendsig(sig_t catcher, ksiginfo_t *ksi, sigset_t *mask)
{
        struct l_rt_sigframe sf, *sfp;
        struct proc *p;
        struct thread *td;
        struct sigacts *psp;
        char *sp;
        struct trapframe *regs;
        int sig, code;
        int oonstack, issiginfo;

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

        LINUX_CTR4(rt_sendsig, "%p, %d, %p, %u",
            catcher, sig, mask, code);

        bzero(&sf, sizeof(sf));
        sf.sf_uc.uc_stack.ss_sp = PTROUT(td->td_sigstk.ss_sp);
        sf.sf_uc.uc_stack.ss_size = td->td_sigstk.ss_size;
        sf.sf_uc.uc_stack.ss_flags = (td->td_pflags & TDP_ALTSTACK)
            ? ((oonstack) ? LINUX_SS_ONSTACK : 0) : LINUX_SS_DISABLE;

        /* 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;
        } else
                sp = (char *)regs->tf_rsp - 128;

        mtx_unlock(&psp->ps_mtx);
        PROC_UNLOCK(p);

        if (linux_copyout_fpstate(td, &sf.sf_uc, &sp) != 0) {
                uprintf("pid %d comm %s linux can't save fpu state, killing\n",
                    p->p_pid, p->p_comm);
                PROC_LOCK(p);
                sigexit(td, SIGILL);
        }
        sf.sf_uc.uc_mcontext.sc_fpstate = (register_t)sp;

        /* Make room, keeping the stack aligned. */
        sp -= sizeof(struct l_rt_sigframe);
        sfp = (struct l_rt_sigframe *)((unsigned long)sp & ~0xFul);

        /* Save user context. */
        bsd_to_linux_sigset(mask, &sf.sf_uc.uc_sigmask);
        sf.sf_uc.uc_mcontext.sc_mask   = sf.sf_uc.uc_sigmask;
        sf.sf_uc.uc_mcontext.sc_rdi    = regs->tf_rdi;
        sf.sf_uc.uc_mcontext.sc_rsi    = regs->tf_rsi;
        sf.sf_uc.uc_mcontext.sc_rdx    = regs->tf_rdx;
        sf.sf_uc.uc_mcontext.sc_rbp    = regs->tf_rbp;
        sf.sf_uc.uc_mcontext.sc_rbx    = regs->tf_rbx;
        sf.sf_uc.uc_mcontext.sc_rcx    = regs->tf_rcx;
        sf.sf_uc.uc_mcontext.sc_rax    = regs->tf_rax;
        sf.sf_uc.uc_mcontext.sc_rip    = regs->tf_rip;
        sf.sf_uc.uc_mcontext.sc_rsp    = regs->tf_rsp;
        sf.sf_uc.uc_mcontext.sc_r8     = regs->tf_r8;
        sf.sf_uc.uc_mcontext.sc_r9     = regs->tf_r9;
        sf.sf_uc.uc_mcontext.sc_r10    = regs->tf_r10;
        sf.sf_uc.uc_mcontext.sc_r11    = regs->tf_r11;
        sf.sf_uc.uc_mcontext.sc_r12    = regs->tf_r12;
        sf.sf_uc.uc_mcontext.sc_r13    = regs->tf_r13;
        sf.sf_uc.uc_mcontext.sc_r14    = regs->tf_r14;
        sf.sf_uc.uc_mcontext.sc_r15    = regs->tf_r15;
        sf.sf_uc.uc_mcontext.sc_cs     = regs->tf_cs;
        sf.sf_uc.uc_mcontext.sc_rflags = regs->tf_rflags;
        sf.sf_uc.uc_mcontext.sc_err    = regs->tf_err;
        sf.sf_uc.uc_mcontext.sc_trapno = bsd_to_linux_trapcode(code);
        sf.sf_uc.uc_mcontext.sc_cr2    = (register_t)ksi->ksi_addr;

        /* Translate the signal. */
        sig = bsd_to_linux_signal(sig);
        /* Fill in POSIX parts. */
        siginfo_to_lsiginfo(&ksi->ksi_info, &sf.sf_si, sig);

        /* Copy the sigframe out to the user's stack. */
        if (copyout(&sf, sfp, sizeof(*sfp)) != 0) {
                uprintf("pid %d comm %s has trashed its stack, killing\n",
                    p->p_pid, p->p_comm);
                PROC_LOCK(p);
                sigexit(td, SIGILL);
        }

        fpstate_drop(td);
        /* Build the argument list for the signal handler. */
        regs->tf_rdi = sig;                     /* arg 1 in %rdi */
        regs->tf_rax = 0;
        if (issiginfo) {
                regs->tf_rsi = (register_t)&sfp->sf_si; /* arg 2 in %rsi */
                regs->tf_rdx = (register_t)&sfp->sf_uc; /* arg 3 in %rdx */
        } else {
                regs->tf_rsi = 0;
                regs->tf_rdx = 0;
        }
        regs->tf_rcx = (register_t)catcher;
        regs->tf_rsp = (long)sfp;
        regs->tf_rip = linux_rt_sigcode;
        regs->tf_rflags &= ~(PSL_T | PSL_D);
        regs->tf_cs = _ucodesel;
        set_pcb_flags(td->td_pcb, PCB_FULL_IRET);
        PROC_LOCK(p);
        mtx_lock(&psp->ps_mtx);
}

#define LINUX_VSYSCALL_START            (-10UL << 20)
#define LINUX_VSYSCALL_SZ               1024

const unsigned long linux_vsyscall_vector[] = {
        LINUX_SYS_gettimeofday,
        LINUX_SYS_linux_time,
        LINUX_SYS_linux_getcpu,
};

static int
linux_vsyscall(struct thread *td)
{
        struct trapframe *frame;
        uint64_t retqaddr;
        int code, traced;
        int error;

        frame = td->td_frame;

        /* Check %rip for vsyscall area. */
        if (__predict_true(frame->tf_rip < LINUX_VSYSCALL_START))
                return (EINVAL);
        if ((frame->tf_rip & (LINUX_VSYSCALL_SZ - 1)) != 0)
                return (EINVAL);
        code = (frame->tf_rip - LINUX_VSYSCALL_START) / LINUX_VSYSCALL_SZ;
        if (code >= nitems(linux_vsyscall_vector))
                return (EINVAL);

        /*
         * vsyscall called as callq *(%rax), so we must
         * use return address from %rsp and also fixup %rsp.
         */
        error = copyin((void *)frame->tf_rsp, &retqaddr, sizeof(retqaddr));
        if (error)
                return (error);

        frame->tf_rip = retqaddr;
        frame->tf_rax = linux_vsyscall_vector[code];
        frame->tf_rsp += 8;

        traced = (frame->tf_flags & PSL_T);

        amd64_syscall(td, traced);

        return (0);
}

struct sysentvec elf_linux_sysvec = {
        .sv_size        = LINUX_SYS_MAXSYSCALL,
        .sv_table       = linux_sysent,
        .sv_fixup       = __elfN(freebsd_fixup),
        .sv_sendsig     = linux_rt_sendsig,
        .sv_sigcode     = &_binary_linux_vdso_so_o_start,
        .sv_szsigcode   = &linux_szsigcode,
        .sv_name        = "Linux ELF64",
        .sv_coredump    = elf64_coredump,
        .sv_elf_core_osabi = ELFOSABI_NONE,
        .sv_elf_core_abi_vendor = LINUX_ABI_VENDOR,
        .sv_elf_core_prepare_notes = linux64_prepare_notes,
        .sv_minsigstksz = LINUX_MINSIGSTKSZ,
        .sv_minuser     = VM_MIN_ADDRESS,
        .sv_maxuser     = VM_MAXUSER_ADDRESS_LA48,
        .sv_usrstack    = LINUX_USRSTACK_LA48,
        .sv_psstrings   = LINUX_PS_STRINGS_LA48,
        .sv_psstringssz = sizeof(struct ps_strings),
        .sv_stackprot   = VM_PROT_ALL,
        .sv_copyout_auxargs = __linuxN(copyout_auxargs),
        .sv_copyout_strings = __linuxN(copyout_strings),
        .sv_setregs     = linux_exec_setregs,
        .sv_fixlimit    = NULL,
        .sv_maxssiz     = NULL,
        .sv_flags       = SV_ABI_LINUX | SV_LP64 | SV_SHP | SV_SIG_DISCIGN |
            SV_SIG_WAITNDQ | SV_TIMEKEEP,
        .sv_set_syscall_retval = linux_set_syscall_retval,
        .sv_fetch_syscall_args = linux_fetch_syscall_args,
        .sv_syscallnames = linux_syscallnames,
        .sv_shared_page_base = LINUX_SHAREDPAGE_LA48,
        .sv_shared_page_len = PAGE_SIZE,
        .sv_schedtail   = linux_schedtail,
        .sv_thread_detach = linux_thread_detach,
        .sv_trap        = linux_vsyscall,
        .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 = linux_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,
            LINUX_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;
        amd64_lower_shared_page(sv);
        /* 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 x86-64 vDSO tsc_selector: %lu\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 x86-64 vDSO cpu_selector: %lu\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_linux_vdso_so_o_start;
        char *vdso_end = &_binary_linux_vdso_so_o_end;

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

        linux_vdso_base = LINUX_VDSOPAGE_LA48;
        if (hw_lower_amd64_sharedpage != 0)
                linux_vdso_base -= PAGE_SIZE;

        __elfN(linux_vdso_fixup)(vdso_start, linux_vdso_base);

        linux_vdso_obj = __elfN(linux_shared_page_init)
            (&linux_vdso_mapping, LINUX_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, LINUX_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_Ehdr *ehdr;
        const Elf_Shdr *shdr;
        Elf64_Addr *where, val;
        Elf_Size rtype, symidx;
        const Elf_Rela *rela;
        Elf_Addr addr, addend;
        int relacnt;
        int i, j;

        MPASS(offset != 0);

        relacnt = 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:
                        printf("Linux x86_64 vDSO: unexpected Rel section\n");
                        break;
                case SHT_RELA:
                        rela = (const Elf_Rela *)(mapping + shdr[i].sh_offset);
                        relacnt = shdr[i].sh_size / sizeof(*rela);
                }
        }

        for (j = 0; j < relacnt; j++, rela++) {
                where = (Elf_Addr *)(mapping + rela->r_offset);
                addend = rela->r_addend;
                rtype = ELF_R_TYPE(rela->r_info);
                symidx = ELF_R_SYM(rela->r_info);

                switch (rtype) {
                case R_X86_64_NONE:     /* none */
                        break;

                case R_X86_64_RELATIVE: /* B + A */
                        addr = (Elf_Addr)(offset + addend);
                        val = addr;
                        if (*where != val)
                                *where = val;
                        break;
                case R_X86_64_IRELATIVE:
                        printf("Linux x86_64 vDSO: unexpected ifunc relocation, "
                            "symbol index %ld\n", symidx);
                        break;
                default:
                        printf("Linux x86_64 vDSO: unexpected relocation type %ld, "
                            "symbol index %ld\n", rtype, symidx);
                }
        }
}

static const Elf_Brandnote linux64_brandnote = {
        .hdr.n_namesz   = sizeof(GNU_ABI_VENDOR),
        .hdr.n_descsz   = 16,
        .hdr.n_type     = 1,
        .vendor         = GNU_ABI_VENDOR,
        .flags          = BN_TRANSLATE_OSREL,
        .trans_osrel    = linux_trans_osrel
};

static const Elf64_Brandinfo linux_glibc2brand = {
        .brand          = ELFOSABI_LINUX,
        .machine        = EM_X86_64,
        .compat_3_brand = "Linux",
        .interp_path    = "/lib64/ld-linux-x86-64.so.2",
        .sysvec         = &elf_linux_sysvec,
        .interp_newpath = NULL,
        .brand_note     = &linux64_brandnote,
        .flags          = BI_CAN_EXEC_DYN | BI_BRAND_NOTE
};

static const Elf64_Brandinfo linux_glibc2brandshort = {
        .brand          = ELFOSABI_LINUX,
        .machine        = EM_X86_64,
        .compat_3_brand = "Linux",
        .interp_path    = "/lib64/ld-linux.so.2",
        .sysvec         = &elf_linux_sysvec,
        .interp_newpath = NULL,
        .brand_note     = &linux64_brandnote,
        .flags          = BI_CAN_EXEC_DYN | BI_BRAND_NOTE
};

static const Elf64_Brandinfo linux_muslbrand = {
        .brand          = ELFOSABI_LINUX,
        .machine        = EM_X86_64,
        .compat_3_brand = "Linux",
        .interp_path    = "/lib/ld-musl-x86_64.so.1",
        .sysvec         = &elf_linux_sysvec,
        .interp_newpath = NULL,
        .brand_note     = &linux64_brandnote,
        .flags          = BI_CAN_EXEC_DYN | BI_BRAND_NOTE |
                            LINUX_BI_FUTEX_REQUEUE
};

static const Elf64_Brandinfo *linux_brandlist[] = {
        &linux_glibc2brand,
        &linux_glibc2brandshort,
        &linux_muslbrand,
        NULL
};

static int
linux64_elf_modevent(module_t mod, int type, void *data)
{
        const Elf64_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 (elf64_insert_brand_entry(*brandinfo) < 0)
                                error = EINVAL;
                if (error == 0) {
                        SET_FOREACH(lihp, linux_ioctl_handler_set)
                                linux_ioctl_register_handler(*lihp);
                        stclohz = (stathz ? stathz : hz);
                        if (bootverbose)
                                printf("Linux x86-64 ELF exec handler installed\n");
                } else
                        printf("cannot insert Linux x86-64 ELF brand handler\n");
                break;
        case MOD_UNLOAD:
                for (brandinfo = &linux_brandlist[0]; *brandinfo != NULL;
                     ++brandinfo)
                        if (elf64_brand_inuse(*brandinfo))
                                error = EBUSY;
                if (error == 0) {
                        for (brandinfo = &linux_brandlist[0];
                             *brandinfo != NULL; ++brandinfo)
                                if (elf64_remove_brand_entry(*brandinfo) < 0)
                                        error = EINVAL;
                }
                if (error == 0) {
                        SET_FOREACH(lihp, linux_ioctl_handler_set)
                                linux_ioctl_unregister_handler(*lihp);
                        if (bootverbose)
                                printf("Linux x86_64 ELF exec handler removed\n");
                } else
                        printf("Could not deinstall Linux x86_64 ELF interpreter entry\n");
                break;
        default:
                return (EOPNOTSUPP);
        }
        return (error);
}

static moduledata_t linux64_elf_mod = {
        "linux64elf",
        linux64_elf_modevent,
        0
};

DECLARE_MODULE_TIED(linux64elf, linux64_elf_mod, SI_SUB_EXEC, SI_ORDER_ANY);
MODULE_DEPEND(linux64elf, linux_common, 1, 1, 1);
FEATURE(linux64, "Linux 64bit support");