/*
 * db_sysctl.c
 *
 * Copyright (c) 2000 Whistle Communications, Inc.
 * All rights reserved.
 * 
 * Subject to the following obligations and disclaimer of warranty, use and
 * redistribution of this software, in source or object code forms, with or
 * without modifications are expressly permitted by Whistle Communications;
 * provided, however, that:
 * 1. Any and all reproductions of the source or object code must include the
 *    copyright notice above and the following disclaimer of warranties; and
 * 2. No rights are granted, in any manner or form, to use Whistle
 *    Communications, Inc. trademarks, including the mark "WHISTLE
 *    COMMUNICATIONS" on advertising, endorsements, or otherwise except as
 *    such appears in the above copyright notice or in the software.
 * 
 * THIS SOFTWARE IS BEING PROVIDED BY WHISTLE COMMUNICATIONS "AS IS", AND
 * TO THE MAXIMUM EXTENT PERMITTED BY LAW, WHISTLE COMMUNICATIONS MAKES NO
 * REPRESENTATIONS OR WARRANTIES, EXPRESS OR IMPLIED, REGARDING THIS SOFTWARE,
 * INCLUDING WITHOUT LIMITATION, ANY AND ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR NON-INFRINGEMENT.
 * WHISTLE COMMUNICATIONS DOES NOT WARRANT, GUARANTEE, OR MAKE ANY
 * REPRESENTATIONS REGARDING THE USE OF, OR THE RESULTS OF THE USE OF THIS
 * SOFTWARE IN TERMS OF ITS CORRECTNESS, ACCURACY, RELIABILITY OR OTHERWISE.
 * IN NO EVENT SHALL WHISTLE COMMUNICATIONS BE LIABLE FOR ANY DAMAGES
 * RESULTING FROM OR ARISING OUT OF ANY USE OF THIS SOFTWARE, INCLUDING
 * WITHOUT LIMITATION, ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,
 * PUNITIVE, OR CONSEQUENTIAL DAMAGES, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES, LOSS OF USE, DATA OR PROFITS, HOWEVER CAUSED AND UNDER 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 WHISTLE COMMUNICATIONS IS ADVISED OF THE POSSIBILITY
 * OF SUCH DAMAGE.
 *
 * Author: Archie Cobbs <archie@whistle.com>
 *
 * $FreeBSD: src/sys/ddb/db_sysctl.c,v 1.1.4.1 2000/08/03 00:09:27 ps Exp $
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/sysctl.h>
#include <sys/reboot.h>

#define DESCRIPTION     "Set to `ddb' or `gdb' to enter the kernel debugger"
#define READ_MODE       ""
#define MODE_DDB        "ddb"
#define MODE_GDB        "gdb"

/*
 * This sysctl forces the kernel to enter the debugger.
 */
static int
sysctl_debug_enter_debugger(SYSCTL_HANDLER_ARGS)
{
        char dmode[64];
        int error;

        strncpy(dmode, READ_MODE, sizeof(dmode) - 1);
        dmode[sizeof(dmode) - 1] = '\0';
        error = sysctl_handle_string(oidp, &dmode[0], sizeof(dmode), req);

        if (error == 0 && req->newptr != NULL) {
                if (strcmp(dmode, MODE_DDB) == 0)
                        boothowto &= ~RB_GDB;
                else if (strcmp(dmode, MODE_GDB) == 0)
                        boothowto |= RB_GDB;
                else
                        return EINVAL;
                Debugger("debug.enter_debugger");
        }
        return error;
}
SYSCTL_PROC(_debug, OID_AUTO, enter_debugger, CTLTYPE_STRING | CTLFLAG_RW,
    0, 0, sysctl_debug_enter_debugger, "A", DESCRIPTION);

/*
 * This sysctl forces a kernel panic.
 */
static int
sysctl_debug_panic(SYSCTL_HANDLER_ARGS)
{
        int err;
        int val = 0;

        err = sysctl_handle_int(oidp, &val, 0, req);
        if (val == 1)
                panic("sysctl_debug_panic");
        return err;
}
SYSCTL_PROC(_debug, OID_AUTO, panic, CTLTYPE_INT | CTLFLAG_RW, 0, 0,
            sysctl_debug_panic, "I", "Set to panic the system");

/*
 * This sysctl forces a kernel stack guard panic.  If you don't get
 * a nice clean page-fault guard panic message then the guard isn't
 * working.
 */
#pragma GCC diagnostic push
#if defined(__GNUC__) && __GNUC__ >= 12
#pragma GCC diagnostic ignored "-Winfinite-recursion"
#endif
static void
stack_guard_panic2(void)
{
        volatile char dummy[128];

        stack_guard_panic2();
        /* NOT REACHED */
        kprintf("%p", dummy);   /* dummy to force dummy[] to be allocated */
}
#pragma GCC diagnostic pop

static int
sysctl_debug_panic2(SYSCTL_HANDLER_ARGS)
{
        int err;
        int val = 0;

        err = sysctl_handle_int(oidp, &val, 0, req);
        if (val == 1)
                stack_guard_panic2();
        return err;
}
SYSCTL_PROC(_debug, OID_AUTO, panic2, CTLTYPE_INT | CTLFLAG_RW, 0, 0,
            sysctl_debug_panic2, "I", "Set to panic the system w/stack guard");