/*      $NetBSD: netbsd32_machdep_16.c,v 1.8 2023/12/20 06:36:01 thorpej Exp $  */

/*
 * Copyright (c) 2001 Wasabi Systems, Inc.
 * All rights reserved.
 *
 * Written by Frank van der Linden for Wasabi Systems, Inc.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed for the NetBSD Project by
 *      Wasabi Systems, Inc.
 * 4. The name of Wasabi Systems, Inc. may not be used to endorse
 *    or promote products derived from this software without specific prior
 *    written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY WASABI SYSTEMS, INC. ``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 WASABI SYSTEMS, INC
 * 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.
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: netbsd32_machdep_16.c,v 1.8 2023/12/20 06:36:01 thorpej Exp $");

#ifdef _KERNEL_OPT
#include "opt_compat_netbsd.h"
#include "opt_execfmt.h"
#endif

#include <sys/param.h>
#include <sys/exec.h>
#include <sys/exec_aout.h>
#include <sys/kmem.h>
#include <sys/proc.h>
#include <sys/signalvar.h>
#include <sys/systm.h>
#include <sys/core.h>
#include <sys/mount.h>
#include <sys/buf.h>
#include <sys/vnode.h>
#include <sys/ras.h>
#include <sys/ptrace.h>
#include <sys/kauth.h>
#include <sys/module_hook.h>

#include <x86/fpu.h>
#include <x86/dbregs.h>
#include <machine/frame.h>
#include <machine/reg.h>
#include <machine/vmparam.h>
#include <machine/netbsd32_machdep.h>
#include <machine/sysarch.h>
#include <machine/userret.h>

#include <compat/netbsd32/netbsd32.h>
#include <compat/netbsd32/netbsd32_exec.h>
#include <compat/netbsd32/netbsd32_syscallargs.h>

#include <compat/sys/signal.h>
#include <compat/sys/signalvar.h>

void netbsd32_buildcontext(struct lwp *, struct trapframe *, void *,
    sig_t, int);

int check_sigcontext32(struct lwp *, const struct netbsd32_sigcontext *);

static void
netbsd32_sendsig_sigcontext(const ksiginfo_t *ksi, const sigset_t *mask)
{
        struct lwp *l = curlwp;
        struct proc *p = l->l_proc;
        struct trapframe *tf;
        int sig = ksi->ksi_signo;
        sig_t catcher = SIGACTION(p, sig).sa_handler;
        struct netbsd32_sigframe_sigcontext *fp, frame;
        int onstack, error;
        struct sigacts *ps = p->p_sigacts;

        tf = l->l_md.md_regs;

        /* Do we need to jump onto the signal stack? */
        onstack =
            (l->l_sigstk.ss_flags & (SS_DISABLE | SS_ONSTACK)) == 0 &&
            (SIGACTION(p, sig).sa_flags & SA_ONSTACK) != 0;

        /* Allocate space for the signal handler context. */
        if (onstack)
                fp = (struct netbsd32_sigframe_sigcontext *)
                    ((char *)l->l_sigstk.ss_sp + l->l_sigstk.ss_size);
        else
                fp = (struct netbsd32_sigframe_sigcontext *)tf->tf_rsp;
        fp--;

        memset(&frame, 0, sizeof(frame));

        /* Build stack frame for signal trampoline. */
        switch (ps->sa_sigdesc[sig].sd_vers) {
        case __SIGTRAMP_SIGCODE_VERSION:
                frame.sf_ra = (uint32_t)(u_long)p->p_sigctx.ps_sigcode;
                break;
        case __SIGTRAMP_SIGCONTEXT_VERSION:
                frame.sf_ra = (uint32_t)(u_long)ps->sa_sigdesc[sig].sd_tramp;
                break;
        default:
                /* Don't know what trampoline version; kill it. */
                sigexit(l, SIGILL);
        }
        frame.sf_signum = sig;
        frame.sf_code = ksi->ksi_trap;
        frame.sf_scp = (uint32_t)(u_long)&fp->sf_sc;

        frame.sf_sc.sc_ds = tf->tf_ds & 0xFFFF;
        frame.sf_sc.sc_es = tf->tf_es & 0xFFFF;
        frame.sf_sc.sc_fs = tf->tf_fs & 0xFFFF;
        frame.sf_sc.sc_gs = tf->tf_gs & 0xFFFF;

        frame.sf_sc.sc_eflags = tf->tf_rflags;
        frame.sf_sc.sc_edi = tf->tf_rdi;
        frame.sf_sc.sc_esi = tf->tf_rsi;
        frame.sf_sc.sc_ebp = tf->tf_rbp;
        frame.sf_sc.sc_ebx = tf->tf_rbx;
        frame.sf_sc.sc_edx = tf->tf_rdx;
        frame.sf_sc.sc_ecx = tf->tf_rcx;
        frame.sf_sc.sc_eax = tf->tf_rax;
        frame.sf_sc.sc_eip = tf->tf_rip;
        frame.sf_sc.sc_cs = tf->tf_cs & 0xFFFF;
        frame.sf_sc.sc_esp = tf->tf_rsp;
        frame.sf_sc.sc_ss = tf->tf_ss & 0xFFFF;
        frame.sf_sc.sc_trapno = tf->tf_trapno;
        frame.sf_sc.sc_err = tf->tf_err;

        /* Save signal stack. */
        frame.sf_sc.sc_onstack = l->l_sigstk.ss_flags & SS_ONSTACK;

        /* Save signal mask. */
        frame.sf_sc.sc_mask = *mask;

        sendsig_reset(l, sig);

        mutex_exit(p->p_lock);
        error = copyout(&frame, fp, sizeof(frame));
        mutex_enter(p->p_lock);

        if (error != 0) {
                /*
                 * Process has trashed its stack; give it an illegal
                 * instruction to halt it in its tracks.
                 */
                sigexit(l, SIGILL);
                /* NOTREACHED */
        }

        netbsd32_buildcontext(l, tf, fp, catcher, onstack);
}

int
compat_16_netbsd32___sigreturn14(struct lwp *l,
    const struct compat_16_netbsd32___sigreturn14_args *uap,
    register_t *retval)
{
        /* {
                syscallarg(netbsd32_sigcontextp_t) sigcntxp;
        } */
        struct netbsd32_sigcontext *scp, context;
        struct proc *p = l->l_proc;
        struct trapframe *tf;
        int error;

        /*
         * The trampoline code hands us the context.
         * It is unsafe to keep track of it ourselves, in the event that a
         * program jumps out of a signal handler.
         */
        scp = NETBSD32PTR64(SCARG(uap, sigcntxp));
        if (copyin(scp, &context, sizeof(*scp)) != 0)
                return (EFAULT);

        /*
         * Check for security violations.
         */
        error = check_sigcontext32(l, &context);
        if (error != 0)
                return error;

        /* Restore register context. */
        tf = l->l_md.md_regs;
        tf->tf_ds = context.sc_ds & 0xFFFF;
        tf->tf_es = context.sc_es & 0xFFFF;
        cpu_fsgs_reload(l, context.sc_fs, context.sc_gs);
        tf->tf_rflags = context.sc_eflags;
        tf->tf_rdi = context.sc_edi;
        tf->tf_rsi = context.sc_esi;
        tf->tf_rbp = context.sc_ebp;
        tf->tf_rbx = context.sc_ebx;
        tf->tf_rdx = context.sc_edx;
        tf->tf_rcx = context.sc_ecx;
        tf->tf_rax = context.sc_eax;

        tf->tf_rip = context.sc_eip;
        tf->tf_cs = context.sc_cs & 0xFFFF;
        tf->tf_rsp = context.sc_esp;
        tf->tf_ss = context.sc_ss & 0xFFFF;

        mutex_enter(p->p_lock);
        /* Restore signal stack. */
        if (context.sc_onstack & SS_ONSTACK)
                l->l_sigstk.ss_flags |= SS_ONSTACK;
        else
                l->l_sigstk.ss_flags &= ~SS_ONSTACK;
        /* Restore signal mask. */
        (void) sigprocmask1(l, SIG_SETMASK, &context.sc_mask, 0);
        mutex_exit(p->p_lock);

        return (EJUSTRETURN);
}

void
netbsd32_machdep_md_16_init(void)
{

        MODULE_HOOK_SET(netbsd32_sendsig_sigcontext_16_hook,
            netbsd32_sendsig_sigcontext);
}

void
netbsd32_machdep_md_16_fini(void)
{

        MODULE_HOOK_UNSET(netbsd32_sendsig_sigcontext_16_hook);
}