/*
 * Kprobe module for testing crash dumps
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 *
 * Copyright (C) IBM Corporation, 2006
 *
 * Author: Ankita Garg <ankita@in.ibm.com>
 *
 * This module induces system failures at predefined crashpoints to
 * evaluate the reliability of crash dumps obtained using different dumping
 * solutions.
 *
 * It is adapted from the Linux Kernel Dump Test Tool by
 * Fernando Luis Vazquez Cao <http://lkdtt.sourceforge.net>
 *
 * Usage :  insmod lkdtm.ko [recur_count={>0}] cpoint_name=<> cpoint_type=<>
 *                                                      [cpoint_count={>0}]
 *
 * recur_count : Recursion level for the stack overflow test. Default is 10.
 *
 * cpoint_name : Crash point where the kernel is to be crashed. It can be
 *               one of INT_HARDWARE_ENTRY, INT_HW_IRQ_EN, INT_TASKLET_ENTRY,
 *               FS_DEVRW, MEM_SWAPOUT, TIMERADD, SCSI_DISPATCH_CMD,
 *               IDE_CORE_CP
 *
 * cpoint_type : Indicates the action to be taken on hitting the crash point.
 *               It can be one of PANIC, BUG, EXCEPTION, LOOP, OVERFLOW
 *
 * cpoint_count : Indicates the number of times the crash point is to be hit
 *                to trigger an action. The default is 10.
 */

#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/module.h>
#include <linux/buffer_head.h>
#include <linux/kprobes.h>
#include <linux/list.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/hrtimer.h>
#include <scsi/scsi_cmnd.h>

#ifdef CONFIG_IDE
#include <linux/ide.h>
#endif

#define NUM_CPOINTS 8
#define NUM_CPOINT_TYPES 5
#define DEFAULT_COUNT 10
#define REC_NUM_DEFAULT 10

enum cname {
        INVALID,
        INT_HARDWARE_ENTRY,
        INT_HW_IRQ_EN,
        INT_TASKLET_ENTRY,
        FS_DEVRW,
        MEM_SWAPOUT,
        TIMERADD,
        SCSI_DISPATCH_CMD,
        IDE_CORE_CP
};

enum ctype {
        NONE,
        PANIC,
        BUG,
        EXCEPTION,
        LOOP,
        OVERFLOW
};

static char* cp_name[] = {
        "INT_HARDWARE_ENTRY",
        "INT_HW_IRQ_EN",
        "INT_TASKLET_ENTRY",
        "FS_DEVRW",
        "MEM_SWAPOUT",
        "TIMERADD",
        "SCSI_DISPATCH_CMD",
        "IDE_CORE_CP"
};

static char* cp_type[] = {
        "PANIC",
        "BUG",
        "EXCEPTION",
        "LOOP",
        "OVERFLOW"
};

static struct jprobe lkdtm;

static int lkdtm_parse_commandline(void);
static void lkdtm_handler(void);

static char* cpoint_name;
static char* cpoint_type;
static int cpoint_count = DEFAULT_COUNT;
static int recur_count = REC_NUM_DEFAULT;

static enum cname cpoint = INVALID;
static enum ctype cptype = NONE;
static int count = DEFAULT_COUNT;

module_param(recur_count, int, 0644);
MODULE_PARM_DESC(recur_count, " Recursion level for the stack overflow test, "\
                                 "default is 10");
module_param(cpoint_name, charp, 0644);
MODULE_PARM_DESC(cpoint_name, " Crash Point, where kernel is to be crashed");
module_param(cpoint_type, charp, 0644);
MODULE_PARM_DESC(cpoint_type, " Crash Point Type, action to be taken on "\
                                "hitting the crash point");
module_param(cpoint_count, int, 0644);
MODULE_PARM_DESC(cpoint_count, " Crash Point Count, number of times the "\
                                "crash point is to be hit to trigger action");

unsigned int jp_do_irq(unsigned int irq)
{
        lkdtm_handler();
        jprobe_return();
        return 0;
}

irqreturn_t jp_handle_irq_event(unsigned int irq, struct irqaction *action)
{
        lkdtm_handler();
        jprobe_return();
        return 0;
}

void jp_tasklet_action(struct softirq_action *a)
{
        lkdtm_handler();
        jprobe_return();
}

void jp_ll_rw_block(int rw, int nr, struct buffer_head *bhs[])
{
        lkdtm_handler();
        jprobe_return();
}

struct scan_control;

unsigned long jp_shrink_inactive_list(unsigned long max_scan,
                                struct zone *zone, struct scan_control *sc)
{
        lkdtm_handler();
        jprobe_return();
        return 0;
}

int jp_hrtimer_start(struct hrtimer *timer, ktime_t tim,
                                const enum hrtimer_mode mode)
{
        lkdtm_handler();
        jprobe_return();
        return 0;
}

int jp_scsi_dispatch_cmd(struct scsi_cmnd *cmd)
{
        lkdtm_handler();
        jprobe_return();
        return 0;
}

#ifdef CONFIG_IDE
int jp_generic_ide_ioctl(ide_drive_t *drive, struct file *file,
                        struct block_device *bdev, unsigned int cmd,
                        unsigned long arg)
{
        lkdtm_handler();
        jprobe_return();
        return 0;
}
#endif

static int lkdtm_parse_commandline(void)
{
        int i;

        if (cpoint_name == INVALID || cpoint_type == NONE ||
                                        cpoint_count < 1 || recur_count < 1)
                return -EINVAL;

        for (i = 0; i < NUM_CPOINTS; ++i) {
                if (!strcmp(cpoint_name, cp_name[i])) {
                        cpoint = i + 1;
                        break;
                }
        }

        for (i = 0; i < NUM_CPOINT_TYPES; ++i) {
                if (!strcmp(cpoint_type, cp_type[i])) {
                        cptype = i + 1;
                        break;
                }
        }

        if (cpoint == INVALID || cptype == NONE)
                return -EINVAL;

        count = cpoint_count;

        return 0;
}

static int recursive_loop(int a)
{
        char buf[1024];

        memset(buf,0xFF,1024);
        recur_count--;
        if (!recur_count)
                return 0;
        else
                return recursive_loop(a);
}

void lkdtm_handler(void)
{
        printk(KERN_INFO "lkdtm : Crash point %s of type %s hit\n",
                                         cpoint_name, cpoint_type);
        --count;

        if (count == 0) {
                switch (cptype) {
                case NONE:
                        break;
                case PANIC:
                        printk(KERN_INFO "lkdtm : PANIC\n");
                        panic("dumptest");
                        break;
                case BUG:
                        printk(KERN_INFO "lkdtm : BUG\n");
                        BUG();
                        break;
                case EXCEPTION:
                        printk(KERN_INFO "lkdtm : EXCEPTION\n");
                        *((int *) 0) = 0;
                        break;
                case LOOP:
                        printk(KERN_INFO "lkdtm : LOOP\n");
                        for (;;);
                        break;
                case OVERFLOW:
                        printk(KERN_INFO "lkdtm : OVERFLOW\n");
                        (void) recursive_loop(0);
                        break;
                default:
                        break;
                }
                count = cpoint_count;
        }
}

int lkdtm_module_init(void)
{
        int ret;

        if (lkdtm_parse_commandline() == -EINVAL) {
                printk(KERN_INFO "lkdtm : Invalid command\n");
                return -EINVAL;
        }

        switch (cpoint) {
        case INT_HARDWARE_ENTRY:
                lkdtm.kp.symbol_name = "__do_IRQ";
                lkdtm.entry = (kprobe_opcode_t*) jp_do_irq;
                break;
        case INT_HW_IRQ_EN:
                lkdtm.kp.symbol_name = "handle_IRQ_event";
                lkdtm.entry = (kprobe_opcode_t*) jp_handle_irq_event;
                break;
        case INT_TASKLET_ENTRY:
                lkdtm.kp.symbol_name = "tasklet_action";
                lkdtm.entry = (kprobe_opcode_t*) jp_tasklet_action;
                break;
        case FS_DEVRW:
                lkdtm.kp.symbol_name = "ll_rw_block";
                lkdtm.entry = (kprobe_opcode_t*) jp_ll_rw_block;
                break;
        case MEM_SWAPOUT:
                lkdtm.kp.symbol_name = "shrink_inactive_list";
                lkdtm.entry = (kprobe_opcode_t*) jp_shrink_inactive_list;
                break;
        case TIMERADD:
                lkdtm.kp.symbol_name = "hrtimer_start";
                lkdtm.entry = (kprobe_opcode_t*) jp_hrtimer_start;
                break;
        case SCSI_DISPATCH_CMD:
                lkdtm.kp.symbol_name = "scsi_dispatch_cmd";
                lkdtm.entry = (kprobe_opcode_t*) jp_scsi_dispatch_cmd;
                break;
        case IDE_CORE_CP:
#ifdef CONFIG_IDE
                lkdtm.kp.symbol_name = "generic_ide_ioctl";
                lkdtm.entry = (kprobe_opcode_t*) jp_generic_ide_ioctl;
#else
                printk(KERN_INFO "lkdtm : Crash point not available\n");
#endif
                break;
        default:
                printk(KERN_INFO "lkdtm : Invalid Crash Point\n");
                break;
        }

        if ((ret = register_jprobe(&lkdtm)) < 0) {
                printk(KERN_INFO "lkdtm : Couldn't register jprobe\n");
                return ret;
        }

        printk(KERN_INFO "lkdtm : Crash point %s of type %s registered\n",
                                                cpoint_name, cpoint_type);
        return 0;
}

void lkdtm_module_exit(void)
{
        unregister_jprobe(&lkdtm);
        printk(KERN_INFO "lkdtm : Crash point unregistered\n");
}

module_init(lkdtm_module_init);
module_exit(lkdtm_module_exit);

MODULE_LICENSE("GPL");