/*      $NetBSD: freebsd_machdep.c,v 1.5 2021/09/07 11:43:03 riastradh Exp $    */

/*-
* Copyright (c) 1998, 2000 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Charles M. Hannum.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
*    notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
*    notice, this list of conditions and the following disclaimer in the
*    documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: freebsd_machdep.c,v 1.5 2021/09/07 11:43:03 riastradh Exp $");

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/signalvar.h>
#include <sys/proc.h>
#include <sys/exec.h>
#include <sys/mount.h>

#include <compat/sys/signal.h>

#include <machine/cpufunc.h>
#include <x86/fpu.h>
#include <machine/reg.h>
#include <machine/vmparam.h>
#include <compat/freebsd/freebsd_machdep.h>


#include <compat/freebsd/freebsd_syscallargs.h>
#include <compat/freebsd/freebsd_exec.h>
#include <compat/freebsd/freebsd_signal.h>

void
freebsd_setregs(struct lwp *l, struct exec_package *epp, vaddr_t stack)
{

       setregs(l, epp, stack);
       fpu_set_default_cw(l, __FreeBSD_NPXCW__);
}

/*
* signal support
*/

/*
* 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.
*/
void
freebsd_sendsig(const ksiginfo_t *ksi, const sigset_t *mask)
{
       int sig = ksi->ksi_signo;
       u_long code = KSI_TRAPCODE(ksi);
       struct lwp *l = curlwp;
       struct proc *p = l->l_proc;
       int onstack, error;
       struct freebsd_sigframe *fp = getframe(l, sig, &onstack), frame;
       sig_t catcher = SIGACTION(p, sig).sa_handler;
       struct trapframe *tf = l->l_md.md_regs;

       fp--;

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

       /* Build stack frame for signal trampoline. */
       frame.sf_signum = sig;
       frame.sf_code = code;
       frame.sf_scp = &fp->sf_sc;
       frame.sf_addr = (char *)rcr2();
       frame.sf_handler = catcher;

       /* Save context. */
       frame.sf_sc.sc_gs = tf->tf_gs;
       frame.sf_sc.sc_fs = tf->tf_fs;
       frame.sf_sc.sc_es = tf->tf_es;
       frame.sf_sc.sc_ds = tf->tf_ds;
       frame.sf_sc.sc_efl = tf->tf_eflags;

       frame.sf_sc.sc_edi = tf->tf_edi;
       frame.sf_sc.sc_esi = tf->tf_esi;
       frame.sf_sc.sc_ebp = tf->tf_ebp;
       frame.sf_sc.sc_isp = 0; /* don't have to pass kernel sp to user. */
       frame.sf_sc.sc_ebx = tf->tf_ebx;
       frame.sf_sc.sc_edx = tf->tf_edx;
       frame.sf_sc.sc_ecx = tf->tf_ecx;
       frame.sf_sc.sc_eax = tf->tf_eax;
       frame.sf_sc.sc_eip = tf->tf_eip;
       frame.sf_sc.sc_cs = tf->tf_cs;
       frame.sf_sc.sc_esp = tf->tf_esp;
       frame.sf_sc.sc_ss = tf->tf_ss;

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

       /* Save signal mask. */
       /* XXX freebsd_osigcontext compat? */
       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 */
       }

       buildcontext(l, GUCODEBIG_SEL, p->p_sigctx.ps_sigcode, fp);

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

/*
* 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
freebsd_sys_sigreturn(struct lwp *l, const struct freebsd_sys_sigreturn_args *uap, register_t *retval)
{
       /* {
               syscallarg(struct freebsd_sigcontext *) scp;
       } */
       struct proc *p = l->l_proc;
       struct freebsd_sigcontext *scp, context;
       struct trapframe *tf;
       sigset_t mask;

       /*
        * 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, scp);
       if (copyin((void *)scp, &context, sizeof(*scp)) != 0)
               return (EFAULT);

       /* Restore register context. */
       tf = l->l_md.md_regs;

       /*
        * Check for security violations.  If we're returning to
        * protected mode, the CPU will validate the segment registers
        * automatically and generate a trap on violations.  We handle
        * the trap, rather than doing all of the checking here.
        */
       if (((context.sc_efl ^ tf->tf_eflags) & PSL_USERSTATIC) != 0 ||
           !USERMODE(context.sc_cs))
               return (EINVAL);

       tf->tf_gs = context.sc_gs;
       tf->tf_fs = context.sc_fs;
       tf->tf_es = context.sc_es;
       tf->tf_ds = context.sc_ds;
       tf->tf_eflags &= ~PSL_USER;
       tf->tf_eflags |= context.sc_efl & PSL_USER;

       tf->tf_edi = context.sc_edi;
       tf->tf_esi = context.sc_esi;
       tf->tf_ebp = context.sc_ebp;
       /* FreeBSD's context.sc_isp is useless. (`popal' ignores it.) */
       tf->tf_ebx = context.sc_ebx;
       tf->tf_edx = context.sc_edx;
       tf->tf_ecx = context.sc_ecx;
       tf->tf_eax = context.sc_eax;
       tf->tf_eip = context.sc_eip;
       tf->tf_cs = context.sc_cs;
       tf->tf_esp = context.sc_esp;
       tf->tf_ss = context.sc_ss;

       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. */
       /* XXX freebsd_osigcontext compat? */
       mask = context.sc_mask;
       (void) sigprocmask1(l, SIG_SETMASK, &mask, 0);
       mutex_exit(p->p_lock);

       return (EJUSTRETURN);
}

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