/* $NetBSD: syscallemu_arm.c,v 1.1 2013/11/10 19:58:38 jmcneill Exp $ */

/*-
 * Copyright (c) 2011 Reinoud Zandijk <reinoud@NetBSD.org>
 * Copyright (c) 2012-2013 Jared D. McNeill <jmcneill@invisible.ca>
 * All rights reserved.
 *
 * 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: syscallemu_arm.c,v 1.1 2013/11/10 19:58:38 jmcneill Exp $");

#include <sys/param.h>
#include <sys/proc.h>
#include <sys/systm.h>

#include <arch/arm/include/locore.h>

#include "syscallemu.h"

#define ARM_TF_PC(frame)        ((frame)->tf_pc)

/*
 * If syscallemu specific data is present for the process, verify that the
 * caller is allowed to execute system calls. If not, deliver a SIGILL to
 * the process. When syscallemu specific data is not present, simply defer
 * to the original syscall handler.
 */
static void
arm_syscall_emu(struct trapframe *frame, struct lwp *l, uint32_t insn)
{
        void (*md_syscall)(struct trapframe *, struct lwp *, uint32_t) = NULL;
        struct syscallemu_data *sce;
        register_t pc_call;
        struct proc *p;
        ksiginfo_t ksi;

        p = l->l_proc;

        pc_call = ARM_TF_PC(frame) - INSN_SIZE;

        /* Determine if we need to emulate the system call */
        sce = syscallemu_getsce(p);
        if (sce) {
                if ((pc_call >= sce->sce_user_start &&
                     pc_call < sce->sce_user_end) ||
                    (pc_call + INSN_SIZE >= sce->sce_user_start &&
                     pc_call + INSN_SIZE < sce->sce_user_end)) {
                        md_syscall = NULL;
                } else {
                        md_syscall = sce->sce_md_syscall;
                }
        } else {
                md_syscall = p->p_md.md_syscall;
        }

        if (md_syscall == NULL) {
                /* If emulating, deliver SIGILL to process */
                ARM_TF_PC(frame) = pc_call;
                KSI_INIT_TRAP(&ksi);
                ksi.ksi_signo = SIGILL;
                ksi.ksi_code = ILL_ILLTRP;
                ksi.ksi_addr = (void *)ARM_TF_PC(frame);
                ksi.ksi_trap = 0;
                trapsignal(l, &ksi);
                userret(l);
        } else {
                /* Not emulating, so treat as a normal syscall */
                KASSERT(md_syscall != NULL);
                md_syscall(frame, l, insn);
        }
}

/*
 * Set p_md.md_syscall to our syscall filter, and return a pointer to the
 * original syscall handler.
 */
void *
md_syscallemu(struct proc *p)
{
        void *osyscall;

        osyscall = p->p_md.md_syscall;
        p->p_md.md_syscall = arm_syscall_emu;

        return osyscall;
}