/*      $NetBSD: sig_machdep.c,v 1.26 2025/04/25 00:26:59 riastradh Exp $       */

/*-
 * Copyright (c) 2003 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Christos Zoulas.
 *
 * 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>                  /* RCS ID & Copyright macro defns */

__KERNEL_RCSID(0, "$NetBSD: sig_machdep.c,v 1.26 2025/04/25 00:26:59 riastradh Exp $");

#include "opt_cputype.h"

#include <sys/param.h>
#include <sys/cpu.h>
#include <sys/kernel.h>
#include <sys/proc.h>
#include <sys/signal.h>
#include <sys/signalvar.h>
#include <sys/mount.h>
#include <sys/syscallargs.h>

#include <mips/frame.h>
#include <mips/regnum.h>
#include <mips/locore.h>

void *
getframe(struct lwp *l, int sig, int *onstack, size_t size, size_t align)
{
        struct proc * const p = l->l_proc;
        struct trapframe * const tf = l->l_md.md_utf;
        uintptr_t sp;

        KASSERT((align & (align - 1)) == 0);

        /* 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;
        if (*onstack)
                sp = (uintptr_t)l->l_sigstk.ss_sp + l->l_sigstk.ss_size;
        else
                sp = (uintptr_t)tf->tf_regs[_R_SP];
        sp -= size;
#ifndef __mips_o32
        if (p->p_md.md_abi == _MIPS_BSD_API_O32)
                sp &= ~(STACK_ALIGNBYTES_O32 | (align - 1));
        else
#endif
                sp &= ~(STACK_ALIGNBYTES | (align - 1));
        return (void *)sp;
}

struct sigframe_siginfo {
        siginfo_t sf_si;
        ucontext_t sf_uc;
};

/*
 * Send a signal to process.
 */
void
sendsig_siginfo(const ksiginfo_t *ksi, const sigset_t *mask)
{
        struct lwp * const l = curlwp;
        struct proc * const p = l->l_proc;
        struct sigacts * const sa = p->p_sigacts;
        struct trapframe * const tf = l->l_md.md_utf;
        int onstack, error;
        const int signo = ksi->ksi_signo;
        struct sigframe_siginfo *sf = getframe(l, signo, &onstack,
            sizeof(*sf), _Alignof(*sf));
        struct sigframe_siginfo ksf;
        const sig_t catcher = SIGACTION(p, signo).sa_handler;

        memset(&ksf, 0, sizeof(ksf));
        ksf.sf_si._info = ksi->ksi_info;
        ksf.sf_uc.uc_flags = _UC_SIGMASK
            | (l->l_sigstk.ss_flags & SS_ONSTACK ? _UC_SETSTACK : _UC_CLRSTACK);
        ksf.sf_uc.uc_sigmask = *mask;
        ksf.sf_uc.uc_link = l->l_ctxlink;
        sendsig_reset(l, signo);

        mutex_exit(p->p_lock);
        cpu_getmcontext(l, &ksf.sf_uc.uc_mcontext, &ksf.sf_uc.uc_flags);
        error = copyout(&ksf, sf, sizeof(ksf));
        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 */
        }

        /*
         * Set up the registers to directly invoke the signal
         * handler.  The return address will be set up to point
         * to the signal trampoline to bounce us back.
         */
        tf->tf_regs[_R_A0] = signo;
        tf->tf_regs[_R_A1] = (intptr_t)&sf->sf_si;
        tf->tf_regs[_R_A2] = (intptr_t)&sf->sf_uc;

        tf->tf_regs[_R_PC] = (intptr_t)catcher;
        tf->tf_regs[_R_T9] = (intptr_t)catcher;
        tf->tf_regs[_R_SP] = (intptr_t)sf;
        tf->tf_regs[_R_RA] = (intptr_t)sa->sa_sigdesc[signo].sd_tramp;

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