/*    $NetBSD: compat_16_machdep.c,v 1.19 2026/03/28 04:32:02 thorpej Exp $   */

/*
 * Copyright (c) 1988 University of Utah.
 * Copyright (c) 1982, 1986, 1990, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * the Systems Programming Group of the University of Utah Computer
 * Science Department.
 *
 * 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.
 *
 *      from: Utah Hdr: machdep.c 1.74 92/12/20
 *      from: @(#)machdep.c     8.10 (Berkeley) 4/20/94
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: compat_16_machdep.c,v 1.19 2026/03/28 04:32:02 thorpej Exp $");

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

#define __M68K_SIGNAL_PRIVATE

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/proc.h>
#include <sys/ras.h>
#include <sys/signal.h>
#include <sys/signalvar.h>
#include <sys/ucontext.h>

#include <sys/mount.h>
#include <sys/syscallargs.h>

#ifdef COMPAT_13
#include <compat/sys/signal.h>
#include <compat/sys/signalvar.h>
#endif

#include <machine/cpu.h>
#include <machine/reg.h>
#include <machine/frame.h>

#ifdef DEBUG
extern int sigdebug;
extern int sigpid;
#define SDB_FOLLOW      0x01
#define SDB_KSTACK      0x02
#define SDB_FPSTATE     0x04
#endif

#ifdef COMPAT_16
/*
 * Send an interrupt to process.
 */
void
sendsig_sigcontext(const ksiginfo_t *ksi, const sigset_t *mask)
{
        struct lwp *l = curlwp;
        struct proc *p = l->l_proc;
        struct sigacts *ps = p->p_sigacts;
        struct frame *frame = (struct frame *)l->l_md.md_regs;
        int onstack, error;
        int sig = ksi->ksi_signo;
        u_long code = KSI_TRAPCODE(ksi);
        struct sigframe_sigcontext *fp = getframe(l, sig, &onstack), kf;
        sig_t catcher = SIGACTION(p, sig).sa_handler;
        short ft = frame->f_format;

        fp--;

#ifdef DEBUG
        if ((sigdebug & SDB_KSTACK) && p->p_pid == sigpid)
                printf("sendsig(%d): sig %d ssp %p usp %p scp %p ft %d\n",
                    p->p_pid, sig, &onstack, fp, &fp->sf_sc, ft);
#endif

        /* Build stack frame for signal trampoline. */
        switch (ps->sa_sigdesc[sig].sd_vers) {
        case __SIGTRAMP_SIGCODE_VERSION:        /* legacy on-stack sigtramp */
                kf.sf_ra = (int)p->p_sigctx.ps_sigcode;
                break;

        case __SIGTRAMP_SIGCONTEXT_VERSION:
                kf.sf_ra = (int)ps->sa_sigdesc[sig].sd_tramp;
                break;

        default:
                /* Don't know what trampoline version; kill it. */
                sigexit(l, SIGILL);
        }

        kf.sf_signum = sig;
        kf.sf_code = code;
        kf.sf_scp = &fp->sf_sc;

        /*
         * Save necessary hardware state.  Currently this includes:
         *      - general registers
         *      - original exception frame (if not a "normal" frame)
         *      - FP coprocessor state
         */
        kf.sf_state.ss_flags = SS_USERREGS;
        memcpy(kf.sf_state.ss_frame.f_regs, frame->f_regs,
            sizeof(frame->f_regs));
        if (ft >= FMT4) {
#ifdef DEBUG
                if (ft > 15 || exframesize[ft] < 0)
                        panic("sendsig: bogus frame type");
#endif
                kf.sf_state.ss_flags |= SS_RTEFRAME;
                kf.sf_state.ss_frame.f_format = frame->f_format;
                kf.sf_state.ss_frame.f_vector = frame->f_vector;
                memcpy(&kf.sf_state.ss_frame.F_u, &frame->F_u,
                    (size_t) exframesize[ft]);
                /*
                 * Leave an indicator that we need to clean up the kernel
                 * stack.  We do this by setting the "pad word" above the
                 * hardware stack frame to the amount the stack must be
                 * adjusted by.
                 *
                 * N.B. we increment rather than just set f_stackadj in
                 * case we are called from syscall when processing a
                 * sigreturn.  In that case, f_stackadj may be non-zero.
                 */
                frame->f_stackadj += exframesize[ft];
                frame->f_format = frame->f_vector = 0;
#ifdef DEBUG
                if (sigdebug & SDB_FOLLOW)
                        printf("sendsig(%d): copy out %d of frame %d\n",
                            p->p_pid, exframesize[ft], ft);
#endif
        }

        if (fputype) {
                kf.sf_state.ss_flags |= SS_FPSTATE;
                m68881_save(&kf.sf_state.ss_fpstate);
        }
#ifdef DEBUG
        if ((sigdebug & SDB_FPSTATE) && *(char *)&kf.sf_state.ss_fpstate)
                printf("sendsig(%d): copy out FP state (%x) to %p\n",
                    p->p_pid, *(u_int *)&kf.sf_state.ss_fpstate,
                    &kf.sf_state.ss_fpstate);
#endif

        /* Build the signal context to be used by sigreturn. */
        kf.sf_sc.sc_sp = frame->f_regs[SP];
        kf.sf_sc.sc_fp = frame->f_regs[A6];
        kf.sf_sc.sc_ap = (int)&fp->sf_state;
        kf.sf_sc.sc_pc = frame->f_pc;
        kf.sf_sc.sc_ps = frame->f_sr;

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

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

#ifdef COMPAT_13
        /*
         * XXX We always have to save an old style signal mask because
         * XXX we might be delivering a signal to a process which will
         * XXX escape from the signal in a non-standard way and invoke
         * XXX sigreturn() directly.
         */
        native_sigset_to_sigset13(mask, &kf.sf_sc.__sc_mask13);
#endif
        sendsig_reset(l, sig);
        mutex_exit(p->p_lock);
        error = copyout(&kf, fp, sizeof(kf));
        mutex_enter(p->p_lock);

        if (error != 0) {
#ifdef DEBUG
                if ((sigdebug & SDB_KSTACK) && p->p_pid == sigpid)
                        printf("sendsig(%d): copyout failed on sig %d\n",
                            p->p_pid, sig);
#endif
                /*
                 * Process has trashed its stack; give it an illegal
                 * instruction to halt it in its tracks.
                 */
                sigexit(l, SIGILL);
                /* NOTREACHED */
        }
#ifdef DEBUG
        if (sigdebug & SDB_FOLLOW)
                printf("sendsig(%d): sig %d scp %p fp %p sc_sp %x sc_ap %x\n",
                    p->p_pid, sig, kf.sf_scp, fp,
                    kf.sf_sc.sc_sp, kf.sf_sc.sc_ap);
#endif

        buildcontext(l, catcher, fp);

        /* Remember that we're now on the signal stack. */
        if (onstack)
                l->l_sigstk.ss_flags |= SS_ONSTACK;

#ifdef DEBUG
        if ((sigdebug & SDB_KSTACK) && p->p_pid == sigpid)
                printf("sendsig(%d): sig %d returns\n",
                    p->p_pid, sig);
#endif
}
#endif

#ifdef COMPAT_16
/*
 * 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
compat_16_sys___sigreturn14(struct lwp *l, const struct compat_16_sys___sigreturn14_args *uap, register_t *retval)
{
        /* {
                syscallarg(struct sigcontext *) sigcntxp;
        } */
        struct proc *p = l->l_proc;
        struct sigcontext *scp;
        struct frame *frame;
        struct sigcontext tsigc;
        struct sigstate tstate;
        int rf, flags, 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 = SCARG(uap, sigcntxp);
#ifdef DEBUG
        if (sigdebug & SDB_FOLLOW)
                printf("sigreturn: pid %d, scp %p\n", p->p_pid, scp);
#endif
        if ((int)scp & 1)
                return EINVAL;

        if (copyin(scp, &tsigc, sizeof(tsigc)) != 0)
                return EFAULT;
        scp = &tsigc;

        /* Make sure the user isn't pulling a fast one on us! */
        if ((scp->sc_ps & (PSL_MBZ|PSL_IPL|PSL_S)) != 0)
                return EINVAL;

        /* Restore register context. */
        frame = (struct frame *) l->l_md.md_regs;

        /*
         * Grab pointer to hardware state information.
         * If zero, the user is probably doing a longjmp.
         */
        if ((rf = scp->sc_ap) == 0)
                goto restore;

        /*
         * See if there is anything to do before we go to the
         * expense of copying in close to 1/2K of data
         */
        error = ufetch_int((void *)rf, (u_int *)&flags);
#ifdef DEBUG
        if (sigdebug & SDB_FOLLOW)
                printf("sigreturn(%d): sc_ap %x flags %x\n",
                    p->p_pid, rf, error ? -1 : flags);
#endif
        /* ufetch_int() failed (bogus sc_ap value). */
        if (error)
                return EINVAL;

        if (flags == 0 || copyin((void *)rf, &tstate, sizeof(tstate)) != 0)
                goto restore;
#ifdef DEBUG
        if ((sigdebug & SDB_KSTACK) && p->p_pid == sigpid)
                printf("sigreturn(%d): ssp %p usp %x scp %p ft %d\n",
                    p->p_pid, &flags, scp->sc_sp, SCARG(uap, sigcntxp),
                    (flags & SS_RTEFRAME) ? tstate.ss_frame.f_format : -1);
#endif
        /*
         * Restore long stack frames.  Note that we do not copy
         * back the saved SR or PC, they were picked up above from
         * the sigcontext structure.
         */
        if (flags & SS_RTEFRAME) {
                register int sz;

                /* grab frame type and validate */
                sz = tstate.ss_frame.f_format;
                if (sz > 15 || (sz = exframesize[sz]) < 0
                                || frame->f_stackadj < sz)
                        return EINVAL;
                frame->f_stackadj -= sz;
                frame->f_format = tstate.ss_frame.f_format;
                frame->f_vector = tstate.ss_frame.f_vector;
                memcpy(&frame->F_u, &tstate.ss_frame.F_u, sz);
#ifdef DEBUG
                if (sigdebug & SDB_FOLLOW)
                        printf("sigreturn(%d): copy in %d of frame type %d\n",
                            p->p_pid, sz, tstate.ss_frame.f_format);
#endif
        }

        /*
         * Restore most of the users registers except for A6 and SP
         * which will be handled below.
         */
        if (flags & SS_USERREGS)
                memcpy(frame->f_regs, tstate.ss_frame.f_regs,
                    sizeof(frame->f_regs) - (2 * NBPW));

        /*
         * Restore the original FP context
         */
        if (fputype && (flags & SS_FPSTATE))
                m68881_restore(&tstate.ss_fpstate);

 restore:
        /*
         * Restore the user supplied information.
         * This should be at the last so that the error (EINVAL)
         * is reported to the sigreturn caller, not to the
         * jump destination.
         */

        frame->f_regs[SP] = scp->sc_sp;
        frame->f_regs[A6] = scp->sc_fp;
        frame->f_pc = scp->sc_pc;
        frame->f_sr = scp->sc_ps;

        mutex_enter(p->p_lock);

        /* Restore signal stack. */
        if (scp->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, &scp->sc_mask, 0);

        mutex_exit(p->p_lock);

#ifdef DEBUG
        if ((sigdebug & SDB_FPSTATE) && *(char *)&tstate.ss_fpstate)
                printf("sigreturn(%d): copied in FP state (%x) at %p\n",
                    p->p_pid, *(u_int *)&tstate.ss_fpstate,
                    &tstate.ss_fpstate);
        if ((sigdebug & SDB_FOLLOW) ||
            ((sigdebug & SDB_KSTACK) && p->p_pid == sigpid))
                printf("sigreturn(%d): returns\n", p->p_pid);
#endif
        return EJUSTRETURN;
}
#endif