drivers/misc/lkdtm.c - third_party/linux - Git at Google

 /*
  * 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>
  *
  * Debugfs support added by Simon Kagstrom <simon.kagstrom@netinsight.net>
  *
  * See Documentation/fault-injection/provoke-crashes.txt for instructions
  */

 #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 <linux/slab.h>
 #include <scsi/scsi_cmnd.h>
 #include <linux/debugfs.h>

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

 #define DEFAULT_COUNT 10
 #define REC_NUM_DEFAULT 10

 enum cname {
 	CN_INVALID,
 	CN_INT_HARDWARE_ENTRY,
 	CN_INT_HW_IRQ_EN,
 	CN_INT_TASKLET_ENTRY,
 	CN_FS_DEVRW,
 	CN_MEM_SWAPOUT,
 	CN_TIMERADD,
 	CN_SCSI_DISPATCH_CMD,
 	CN_IDE_CORE_CP,
 	CN_DIRECT,
 };

 enum ctype {
 	CT_NONE,
 	CT_PANIC,
 	CT_BUG,
 	CT_EXCEPTION,
 	CT_LOOP,
 	CT_OVERFLOW,
 	CT_CORRUPT_STACK,
 	CT_UNALIGNED_LOAD_STORE_WRITE,
 	CT_OVERWRITE_ALLOCATION,
 	CT_WRITE_AFTER_FREE,
 	CT_SOFTLOCKUP,
 	CT_HARDLOCKUP,
 	CT_HUNG_TASK,
 };

 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",
 	"DIRECT",
 };

 static char* cp_type[] = {
 	"PANIC",
 	"BUG",
 	"EXCEPTION",
 	"LOOP",
 	"OVERFLOW",
 	"CORRUPT_STACK",
 	"UNALIGNED_LOAD_STORE_WRITE",
 	"OVERWRITE_ALLOCATION",
 	"WRITE_AFTER_FREE",
 	"SOFTLOCKUP",
 	"HARDLOCKUP",
 	"HUNG_TASK",
 };

 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 = CN_INVALID;
 static enum ctype cptype = CT_NONE;
 static int count = DEFAULT_COUNT;
 static DEFINE_SPINLOCK(count_lock);

 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, 0444);
 MODULE_PARM_DESC(cpoint_name, " Crash Point, where kernel is to be crashed");
 module_param(cpoint_type, charp, 0444);
 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");

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

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

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

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

 struct scan_control;

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

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

 static 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

 /* Return the crashpoint number or NONE if the name is invalid */
 static enum ctype parse_cp_type(const char *what, size_t count)
 {
 	int i;

 	for (i = 0; i < ARRAY_SIZE(cp_type); i++) {
 		if (!strcmp(what, cp_type[i]))
 			return i + 1;
 	}

 	return CT_NONE;
 }

 static const char *cp_type_to_str(enum ctype type)
 {
 	if (type == CT_NONE || type < 0 || type > ARRAY_SIZE(cp_type))
 		return "None";

 	return cp_type[type - 1];
 }

 static const char *cp_name_to_str(enum cname name)
 {
 	if (name == CN_INVALID || name < 0 || name > ARRAY_SIZE(cp_name))
 		return "INVALID";

 	return cp_name[name - 1];
 }


 static int lkdtm_parse_commandline(void)
 {
 	int i;
 	unsigned long flags;

 	if (cpoint_count < 1 || recur_count < 1)
 		return -EINVAL;

 	spin_lock_irqsave(&count_lock, flags);
 	count = cpoint_count;
 	spin_unlock_irqrestore(&count_lock, flags);

 	/* No special parameters */
 	if (!cpoint_type && !cpoint_name)
 		return 0;

 	/* Neither or both of these need to be set */
 	if (!cpoint_type || !cpoint_name)
 		return -EINVAL;

 	cptype = parse_cp_type(cpoint_type, strlen(cpoint_type));
 	if (cptype == CT_NONE)
 		return -EINVAL;

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

 	/* Could not find a valid crash point */
 	return -EINVAL;
 }

 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);
 }

 static void lkdtm_do_action(enum ctype which)
 {
 	switch (which) {
 	case CT_PANIC:
 		panic("dumptest");
 		break;
 	case CT_BUG:
 		BUG();
 		break;
 	case CT_EXCEPTION:
 		*((int *) 0) = 0;
 		break;
 	case CT_LOOP:
 		for (;;)
 			;
 		break;
 	case CT_OVERFLOW:
 		(void) recursive_loop(0);
 		break;
 	case CT_CORRUPT_STACK: {
 		volatile u32 data[8];
 		volatile u32 *p = data;

 		p[12] = 0x12345678;
 		break;
 	}
 	case CT_UNALIGNED_LOAD_STORE_WRITE: {
 		static u8 data[5] __attribute__((aligned(4))) = {1, 2,
 				3, 4, 5};
 		u32 *p;
 		u32 val = 0x12345678;

 		p = (u32 *)(data + 1);
 		if (*p == 0)
 			val = 0x87654321;
 		*p = val;
 		 break;
 	}
 	case CT_OVERWRITE_ALLOCATION: {
 		size_t len = 1020;
 		u32 *data = kmalloc(len, GFP_KERNEL);

 		data[1024 / sizeof(u32)] = 0x12345678;
 		kfree(data);
 		break;
 	}
 	case CT_WRITE_AFTER_FREE: {
 		size_t len = 1024;
 		u32 *data = kmalloc(len, GFP_KERNEL);

 		kfree(data);
 		schedule();
 		memset(data, 0x78, len);
 		break;
 	}
 	case CT_SOFTLOCKUP:
 		preempt_disable();
 		for (;;)
 			cpu_relax();
 		break;
 	case CT_HARDLOCKUP:
 		local_irq_disable();
 		for (;;)
 			cpu_relax();
 		break;
 	case CT_HUNG_TASK:
 		set_current_state(TASK_UNINTERRUPTIBLE);
 		schedule();
 		break;
 	case CT_NONE:
 	default:
 		break;
 	}

 }

 static void lkdtm_handler(void)
 {
 	unsigned long flags;
 	bool do_it = false;

 	spin_lock_irqsave(&count_lock, flags);
 	count--;
 	printk(KERN_INFO "lkdtm: Crash point %s of type %s hit, trigger in %d rounds\n",
 			cp_name_to_str(cpoint), cp_type_to_str(cptype), count);

 	if (count == 0) {
 		do_it = true;
 		count = cpoint_count;
 	}
 	spin_unlock_irqrestore(&count_lock, flags);

 	if (do_it)
 		lkdtm_do_action(cptype);
 }

 static int lkdtm_register_cpoint(enum cname which)
 {
 	int ret;

 	cpoint = CN_INVALID;
 	if (lkdtm.entry != NULL)
 		unregister_jprobe(&lkdtm);

 	switch (which) {
 	case CN_DIRECT:
 		lkdtm_do_action(cptype);
 		return 0;
 	case CN_INT_HARDWARE_ENTRY:
 		lkdtm.kp.symbol_name = "do_IRQ";
 		lkdtm.entry = (kprobe_opcode_t*) jp_do_irq;
 		break;
 	case CN_INT_HW_IRQ_EN:
 		lkdtm.kp.symbol_name = "handle_IRQ_event";
 		lkdtm.entry = (kprobe_opcode_t*) jp_handle_irq_event;
 		break;
 	case CN_INT_TASKLET_ENTRY:
 		lkdtm.kp.symbol_name = "tasklet_action";
 		lkdtm.entry = (kprobe_opcode_t*) jp_tasklet_action;
 		break;
 	case CN_FS_DEVRW:
 		lkdtm.kp.symbol_name = "ll_rw_block";
 		lkdtm.entry = (kprobe_opcode_t*) jp_ll_rw_block;
 		break;
 	case CN_MEM_SWAPOUT:
 		lkdtm.kp.symbol_name = "shrink_inactive_list";
 		lkdtm.entry = (kprobe_opcode_t*) jp_shrink_inactive_list;
 		break;
 	case CN_TIMERADD:
 		lkdtm.kp.symbol_name = "hrtimer_start";
 		lkdtm.entry = (kprobe_opcode_t*) jp_hrtimer_start;
 		break;
 	case CN_SCSI_DISPATCH_CMD:
 		lkdtm.kp.symbol_name = "scsi_dispatch_cmd";
 		lkdtm.entry = (kprobe_opcode_t*) jp_scsi_dispatch_cmd;
 		break;
 	case CN_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");
 		return -EINVAL;
 #endif
 		break;
 	default:
 		printk(KERN_INFO "lkdtm: Invalid Crash Point\n");
 		return -EINVAL;
 	}

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

 	return ret;
 }

 static ssize_t do_register_entry(enum cname which, struct file *f,
 		const char __user *user_buf, size_t count, loff_t *off)
 {
 	char *buf;
 	int err;

 	if (count >= PAGE_SIZE)
 		return -EINVAL;

 	buf = (char *)__get_free_page(GFP_KERNEL);
 	if (!buf)
 		return -ENOMEM;
 	if (copy_from_user(buf, user_buf, count)) {
 		free_page((unsigned long) buf);
 		return -EFAULT;
 	}
 	/* NULL-terminate and remove enter */
 	buf[count] = '\0';
 	strim(buf);

 	cptype = parse_cp_type(buf, count);
 	free_page((unsigned long) buf);

 	if (cptype == CT_NONE)
 		return -EINVAL;

 	err = lkdtm_register_cpoint(which);
 	if (err < 0)
 		return err;

 	*off += count;

 	return count;
 }

 /* Generic read callback that just prints out the available crash types */
 static ssize_t lkdtm_debugfs_read(struct file *f, char __user *user_buf,
 		size_t count, loff_t *off)
 {
 	char *buf;
 	int i, n, out;

 	buf = (char *)__get_free_page(GFP_KERNEL);
 	if (buf == NULL)
 		return -ENOMEM;

 	n = snprintf(buf, PAGE_SIZE, "Available crash types:\n");
 	for (i = 0; i < ARRAY_SIZE(cp_type); i++)
 		n += snprintf(buf + n, PAGE_SIZE - n, "%s\n", cp_type[i]);
 	buf[n] = '\0';

 	out = simple_read_from_buffer(user_buf, count, off,
 				      buf, n);
 	free_page((unsigned long) buf);

 	return out;
 }

 static int lkdtm_debugfs_open(struct inode *inode, struct file *file)
 {
 	return 0;
 }


 static ssize_t int_hardware_entry(struct file *f, const char __user *buf,
 		size_t count, loff_t *off)
 {
 	return do_register_entry(CN_INT_HARDWARE_ENTRY, f, buf, count, off);
 }

 static ssize_t int_hw_irq_en(struct file *f, const char __user *buf,
 		size_t count, loff_t *off)
 {
 	return do_register_entry(CN_INT_HW_IRQ_EN, f, buf, count, off);
 }

 static ssize_t int_tasklet_entry(struct file *f, const char __user *buf,
 		size_t count, loff_t *off)
 {
 	return do_register_entry(CN_INT_TASKLET_ENTRY, f, buf, count, off);
 }

 static ssize_t fs_devrw_entry(struct file *f, const char __user *buf,
 		size_t count, loff_t *off)
 {
 	return do_register_entry(CN_FS_DEVRW, f, buf, count, off);
 }

 static ssize_t mem_swapout_entry(struct file *f, const char __user *buf,
 		size_t count, loff_t *off)
 {
 	return do_register_entry(CN_MEM_SWAPOUT, f, buf, count, off);
 }

 static ssize_t timeradd_entry(struct file *f, const char __user *buf,
 		size_t count, loff_t *off)
 {
 	return do_register_entry(CN_TIMERADD, f, buf, count, off);
 }

 static ssize_t scsi_dispatch_cmd_entry(struct file *f,
 		const char __user *buf, size_t count, loff_t *off)
 {
 	return do_register_entry(CN_SCSI_DISPATCH_CMD, f, buf, count, off);
 }

 static ssize_t ide_core_cp_entry(struct file *f, const char __user *buf,
 		size_t count, loff_t *off)
 {
 	return do_register_entry(CN_IDE_CORE_CP, f, buf, count, off);
 }

 /* Special entry to just crash directly. Available without KPROBEs */
 static ssize_t direct_entry(struct file *f, const char __user *user_buf,
 		size_t count, loff_t *off)
 {
 	enum ctype type;
 	char *buf;

 	if (count >= PAGE_SIZE)
 		return -EINVAL;
 	if (count < 1)
 		return -EINVAL;

 	buf = (char *)__get_free_page(GFP_KERNEL);
 	if (!buf)
 		return -ENOMEM;
 	if (copy_from_user(buf, user_buf, count)) {
 		free_page((unsigned long) buf);
 		return -EFAULT;
 	}
 	/* NULL-terminate and remove enter */
 	buf[count] = '\0';
 	strim(buf);

 	type = parse_cp_type(buf, count);
 	free_page((unsigned long) buf);
 	if (type == CT_NONE)
 		return -EINVAL;

 	printk(KERN_INFO "lkdtm: Performing direct entry %s\n",
 			cp_type_to_str(type));
 	lkdtm_do_action(type);
 	*off += count;

 	return count;
 }

 struct crash_entry {
 	const char *name;
 	const struct file_operations fops;
 };

 static const struct crash_entry crash_entries[] = {
 	{"DIRECT", {.read = lkdtm_debugfs_read,
 			.llseek = generic_file_llseek,
 			.open = lkdtm_debugfs_open,
 			.write = direct_entry} },
 	{"INT_HARDWARE_ENTRY", {.read = lkdtm_debugfs_read,
 			.llseek = generic_file_llseek,
 			.open = lkdtm_debugfs_open,
 			.write = int_hardware_entry} },
 	{"INT_HW_IRQ_EN", {.read = lkdtm_debugfs_read,
 			.llseek = generic_file_llseek,
 			.open = lkdtm_debugfs_open,
 			.write = int_hw_irq_en} },
 	{"INT_TASKLET_ENTRY", {.read = lkdtm_debugfs_read,
 			.llseek = generic_file_llseek,
 			.open = lkdtm_debugfs_open,
 			.write = int_tasklet_entry} },
 	{"FS_DEVRW", {.read = lkdtm_debugfs_read,
 			.llseek = generic_file_llseek,
 			.open = lkdtm_debugfs_open,
 			.write = fs_devrw_entry} },
 	{"MEM_SWAPOUT", {.read = lkdtm_debugfs_read,
 			.llseek = generic_file_llseek,
 			.open = lkdtm_debugfs_open,
 			.write = mem_swapout_entry} },
 	{"TIMERADD", {.read = lkdtm_debugfs_read,
 			.llseek = generic_file_llseek,
 			.open = lkdtm_debugfs_open,
 			.write = timeradd_entry} },
 	{"SCSI_DISPATCH_CMD", {.read = lkdtm_debugfs_read,
 			.llseek = generic_file_llseek,
 			.open = lkdtm_debugfs_open,
 			.write = scsi_dispatch_cmd_entry} },
 	{"IDE_CORE_CP",	{.read = lkdtm_debugfs_read,
 			.llseek = generic_file_llseek,
 			.open = lkdtm_debugfs_open,
 			.write = ide_core_cp_entry} },
 };

 static struct dentry *lkdtm_debugfs_root;

 static int __init lkdtm_module_init(void)
 {
 	int ret = -EINVAL;
 	int n_debugfs_entries = 1; /* Assume only the direct entry */
 	int i;

 	/* Register debugfs interface */
 	lkdtm_debugfs_root = debugfs_create_dir("provoke-crash", NULL);
 	if (!lkdtm_debugfs_root) {
 		printk(KERN_ERR "lkdtm: creating root dir failed\n");
 		return -ENODEV;
 	}

 #ifdef CONFIG_KPROBES
 	n_debugfs_entries = ARRAY_SIZE(crash_entries);
 #endif

 	for (i = 0; i < n_debugfs_entries; i++) {
 		const struct crash_entry *cur = &crash_entries[i];
 		struct dentry *de;

 		de = debugfs_create_file(cur->name, 0644, lkdtm_debugfs_root,
 				NULL, &cur->fops);
 		if (de == NULL) {
 			printk(KERN_ERR "lkdtm: could not create %s\n",
 					cur->name);
 			goto out_err;
 		}
 	}

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

 	if (cpoint != CN_INVALID && cptype != CT_NONE) {
 		ret = lkdtm_register_cpoint(cpoint);
 		if (ret < 0) {
 			printk(KERN_INFO "lkdtm: Invalid crash point %d\n",
 					cpoint);
 			goto out_err;
 		}
 		printk(KERN_INFO "lkdtm: Crash point %s of type %s registered\n",
 				cpoint_name, cpoint_type);
 	} else {
 		printk(KERN_INFO "lkdtm: No crash points registered, enable through debugfs\n");
 	}

 	return 0;

 out_err:
 	debugfs_remove_recursive(lkdtm_debugfs_root);
 	return ret;
 }

 static void __exit lkdtm_module_exit(void)
 {
 	debugfs_remove_recursive(lkdtm_debugfs_root);

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

 module_init(lkdtm_module_init);
 module_exit(lkdtm_module_exit);

 MODULE_LICENSE("GPL");
	/*
	* 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>
	*
	* Debugfs support added by Simon Kagstrom <simon.kagstrom@netinsight.net>
	*
	* See Documentation/fault-injection/provoke-crashes.txt for instructions
	*/

	#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 <linux/slab.h>
	#include <scsi/scsi_cmnd.h>
	#include <linux/debugfs.h>

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

	#define DEFAULT_COUNT 10
	#define REC_NUM_DEFAULT 10

	enum cname {
	CN_INVALID,
	CN_INT_HARDWARE_ENTRY,
	CN_INT_HW_IRQ_EN,
	CN_INT_TASKLET_ENTRY,
	CN_FS_DEVRW,
	CN_MEM_SWAPOUT,
	CN_TIMERADD,
	CN_SCSI_DISPATCH_CMD,
	CN_IDE_CORE_CP,
	CN_DIRECT,
	};

	enum ctype {
	CT_NONE,
	CT_PANIC,
	CT_BUG,
	CT_EXCEPTION,
	CT_LOOP,
	CT_OVERFLOW,
	CT_CORRUPT_STACK,
	CT_UNALIGNED_LOAD_STORE_WRITE,
	CT_OVERWRITE_ALLOCATION,
	CT_WRITE_AFTER_FREE,
	CT_SOFTLOCKUP,
	CT_HARDLOCKUP,
	CT_HUNG_TASK,
	};

	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",
	"DIRECT",
	};

	static char* cp_type[] = {
	"PANIC",
	"BUG",
	"EXCEPTION",
	"LOOP",
	"OVERFLOW",
	"CORRUPT_STACK",
	"UNALIGNED_LOAD_STORE_WRITE",
	"OVERWRITE_ALLOCATION",
	"WRITE_AFTER_FREE",
	"SOFTLOCKUP",
	"HARDLOCKUP",
	"HUNG_TASK",
	};

	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 = CN_INVALID;
	static enum ctype cptype = CT_NONE;
	static int count = DEFAULT_COUNT;
	static DEFINE_SPINLOCK(count_lock);

	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, 0444);
	MODULE_PARM_DESC(cpoint_name, " Crash Point, where kernel is to be crashed");
	module_param(cpoint_type, charp, 0444);
	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");

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

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

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

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

	struct scan_control;

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

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

	static 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

	/* Return the crashpoint number or NONE if the name is invalid */
	static enum ctype parse_cp_type(const char *what, size_t count)
	{
	int i;

	for (i = 0; i < ARRAY_SIZE(cp_type); i++) {
	if (!strcmp(what, cp_type[i]))
	return i + 1;
	}

	return CT_NONE;
	}

	static const char *cp_type_to_str(enum ctype type)
	{
	if (type == CT_NONE \|\| type < 0 \|\| type > ARRAY_SIZE(cp_type))
	return "None";

	return cp_type[type - 1];
	}

	static const char *cp_name_to_str(enum cname name)
	{
	if (name == CN_INVALID \|\| name < 0 \|\| name > ARRAY_SIZE(cp_name))
	return "INVALID";

	return cp_name[name - 1];
	}


	static int lkdtm_parse_commandline(void)
	{
	int i;
	unsigned long flags;

	if (cpoint_count < 1 \|\| recur_count < 1)
	return -EINVAL;

	spin_lock_irqsave(&count_lock, flags);
	count = cpoint_count;
	spin_unlock_irqrestore(&count_lock, flags);

	/* No special parameters */
	if (!cpoint_type && !cpoint_name)
	return 0;

	/* Neither or both of these need to be set */
	if (!cpoint_type \|\| !cpoint_name)
	return -EINVAL;

	cptype = parse_cp_type(cpoint_type, strlen(cpoint_type));
	if (cptype == CT_NONE)
	return -EINVAL;

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

	/* Could not find a valid crash point */
	return -EINVAL;
	}

	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);
	}

	static void lkdtm_do_action(enum ctype which)
	{
	switch (which) {
	case CT_PANIC:
	panic("dumptest");
	break;
	case CT_BUG:
	BUG();
	break;
	case CT_EXCEPTION:
	((int ) 0) = 0;
	break;
	case CT_LOOP:
	for (;;)
	;
	break;
	case CT_OVERFLOW:
	(void) recursive_loop(0);
	break;
	case CT_CORRUPT_STACK: {
	volatile u32 data[8];
	volatile u32 *p = data;

	p[12] = 0x12345678;
	break;
	}
	case CT_UNALIGNED_LOAD_STORE_WRITE: {
	static u8 data[5] __attribute__((aligned(4))) = {1, 2,
	3, 4, 5};
	u32 *p;
	u32 val = 0x12345678;

	p = (u32 *)(data + 1);
	if (*p == 0)
	val = 0x87654321;
	*p = val;
	break;
	}
	case CT_OVERWRITE_ALLOCATION: {
	size_t len = 1020;
	u32 *data = kmalloc(len, GFP_KERNEL);

	data[1024 / sizeof(u32)] = 0x12345678;
	kfree(data);
	break;
	}
	case CT_WRITE_AFTER_FREE: {
	size_t len = 1024;
	u32 *data = kmalloc(len, GFP_KERNEL);

	kfree(data);
	schedule();
	memset(data, 0x78, len);
	break;
	}
	case CT_SOFTLOCKUP:
	preempt_disable();
	for (;;)
	cpu_relax();
	break;
	case CT_HARDLOCKUP:
	local_irq_disable();
	for (;;)
	cpu_relax();
	break;
	case CT_HUNG_TASK:
	set_current_state(TASK_UNINTERRUPTIBLE);
	schedule();
	break;
	case CT_NONE:
	default:
	break;
	}

	}

	static void lkdtm_handler(void)
	{
	unsigned long flags;
	bool do_it = false;

	spin_lock_irqsave(&count_lock, flags);
	count--;
	printk(KERN_INFO "lkdtm: Crash point %s of type %s hit, trigger in %d rounds\n",
	cp_name_to_str(cpoint), cp_type_to_str(cptype), count);

	if (count == 0) {
	do_it = true;
	count = cpoint_count;
	}
	spin_unlock_irqrestore(&count_lock, flags);

	if (do_it)
	lkdtm_do_action(cptype);
	}

	static int lkdtm_register_cpoint(enum cname which)
	{
	int ret;

	cpoint = CN_INVALID;
	if (lkdtm.entry != NULL)
	unregister_jprobe(&lkdtm);

	switch (which) {
	case CN_DIRECT:
	lkdtm_do_action(cptype);
	return 0;
	case CN_INT_HARDWARE_ENTRY:
	lkdtm.kp.symbol_name = "do_IRQ";
	lkdtm.entry = (kprobe_opcode_t*) jp_do_irq;
	break;
	case CN_INT_HW_IRQ_EN:
	lkdtm.kp.symbol_name = "handle_IRQ_event";
	lkdtm.entry = (kprobe_opcode_t*) jp_handle_irq_event;
	break;
	case CN_INT_TASKLET_ENTRY:
	lkdtm.kp.symbol_name = "tasklet_action";
	lkdtm.entry = (kprobe_opcode_t*) jp_tasklet_action;
	break;
	case CN_FS_DEVRW:
	lkdtm.kp.symbol_name = "ll_rw_block";
	lkdtm.entry = (kprobe_opcode_t*) jp_ll_rw_block;
	break;
	case CN_MEM_SWAPOUT:
	lkdtm.kp.symbol_name = "shrink_inactive_list";
	lkdtm.entry = (kprobe_opcode_t*) jp_shrink_inactive_list;
	break;
	case CN_TIMERADD:
	lkdtm.kp.symbol_name = "hrtimer_start";
	lkdtm.entry = (kprobe_opcode_t*) jp_hrtimer_start;
	break;
	case CN_SCSI_DISPATCH_CMD:
	lkdtm.kp.symbol_name = "scsi_dispatch_cmd";
	lkdtm.entry = (kprobe_opcode_t*) jp_scsi_dispatch_cmd;
	break;
	case CN_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");
	return -EINVAL;
	#endif
	break;
	default:
	printk(KERN_INFO "lkdtm: Invalid Crash Point\n");
	return -EINVAL;
	}

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

	return ret;
	}

	static ssize_t do_register_entry(enum cname which, struct file *f,
	const char __user user_buf, size_t count, loff_t off)
	{
	char *buf;
	int err;

	if (count >= PAGE_SIZE)
	return -EINVAL;

	buf = (char *)__get_free_page(GFP_KERNEL);
	if (!buf)
	return -ENOMEM;
	if (copy_from_user(buf, user_buf, count)) {
	free_page((unsigned long) buf);
	return -EFAULT;
	}
	/* NULL-terminate and remove enter */
	buf[count] = '\0';
	strim(buf);

	cptype = parse_cp_type(buf, count);
	free_page((unsigned long) buf);

	if (cptype == CT_NONE)
	return -EINVAL;

	err = lkdtm_register_cpoint(which);
	if (err < 0)
	return err;

	*off += count;

	return count;
	}

	/* Generic read callback that just prints out the available crash types */
	static ssize_t lkdtm_debugfs_read(struct file f, char __user user_buf,
	size_t count, loff_t *off)
	{
	char *buf;
	int i, n, out;

	buf = (char *)__get_free_page(GFP_KERNEL);
	if (buf == NULL)
	return -ENOMEM;

	n = snprintf(buf, PAGE_SIZE, "Available crash types:\n");
	for (i = 0; i < ARRAY_SIZE(cp_type); i++)
	n += snprintf(buf + n, PAGE_SIZE - n, "%s\n", cp_type[i]);
	buf[n] = '\0';

	out = simple_read_from_buffer(user_buf, count, off,
	buf, n);
	free_page((unsigned long) buf);

	return out;
	}

	static int lkdtm_debugfs_open(struct inode inode, struct file file)
	{
	return 0;
	}


	static ssize_t int_hardware_entry(struct file f, const char __user buf,
	size_t count, loff_t *off)
	{
	return do_register_entry(CN_INT_HARDWARE_ENTRY, f, buf, count, off);
	}

	static ssize_t int_hw_irq_en(struct file f, const char __user buf,
	size_t count, loff_t *off)
	{
	return do_register_entry(CN_INT_HW_IRQ_EN, f, buf, count, off);
	}

	static ssize_t int_tasklet_entry(struct file f, const char __user buf,
	size_t count, loff_t *off)
	{
	return do_register_entry(CN_INT_TASKLET_ENTRY, f, buf, count, off);
	}

	static ssize_t fs_devrw_entry(struct file f, const char __user buf,
	size_t count, loff_t *off)
	{
	return do_register_entry(CN_FS_DEVRW, f, buf, count, off);
	}

	static ssize_t mem_swapout_entry(struct file f, const char __user buf,
	size_t count, loff_t *off)
	{
	return do_register_entry(CN_MEM_SWAPOUT, f, buf, count, off);
	}

	static ssize_t timeradd_entry(struct file f, const char __user buf,
	size_t count, loff_t *off)
	{
	return do_register_entry(CN_TIMERADD, f, buf, count, off);
	}

	static ssize_t scsi_dispatch_cmd_entry(struct file *f,
	const char __user buf, size_t count, loff_t off)
	{
	return do_register_entry(CN_SCSI_DISPATCH_CMD, f, buf, count, off);
	}

	static ssize_t ide_core_cp_entry(struct file f, const char __user buf,
	size_t count, loff_t *off)
	{
	return do_register_entry(CN_IDE_CORE_CP, f, buf, count, off);
	}

	/* Special entry to just crash directly. Available without KPROBEs */
	static ssize_t direct_entry(struct file f, const char __user user_buf,
	size_t count, loff_t *off)
	{
	enum ctype type;
	char *buf;

	if (count >= PAGE_SIZE)
	return -EINVAL;
	if (count < 1)
	return -EINVAL;

	buf = (char *)__get_free_page(GFP_KERNEL);
	if (!buf)
	return -ENOMEM;
	if (copy_from_user(buf, user_buf, count)) {
	free_page((unsigned long) buf);
	return -EFAULT;
	}
	/* NULL-terminate and remove enter */
	buf[count] = '\0';
	strim(buf);

	type = parse_cp_type(buf, count);
	free_page((unsigned long) buf);
	if (type == CT_NONE)
	return -EINVAL;

	printk(KERN_INFO "lkdtm: Performing direct entry %s\n",
	cp_type_to_str(type));
	lkdtm_do_action(type);
	*off += count;

	return count;
	}

	struct crash_entry {
	const char *name;
	const struct file_operations fops;
	};

	static const struct crash_entry crash_entries[] = {
	{"DIRECT", {.read = lkdtm_debugfs_read,
	.llseek = generic_file_llseek,
	.open = lkdtm_debugfs_open,
	.write = direct_entry} },
	{"INT_HARDWARE_ENTRY", {.read = lkdtm_debugfs_read,
	.llseek = generic_file_llseek,
	.open = lkdtm_debugfs_open,
	.write = int_hardware_entry} },
	{"INT_HW_IRQ_EN", {.read = lkdtm_debugfs_read,
	.llseek = generic_file_llseek,
	.open = lkdtm_debugfs_open,
	.write = int_hw_irq_en} },
	{"INT_TASKLET_ENTRY", {.read = lkdtm_debugfs_read,
	.llseek = generic_file_llseek,
	.open = lkdtm_debugfs_open,
	.write = int_tasklet_entry} },
	{"FS_DEVRW", {.read = lkdtm_debugfs_read,
	.llseek = generic_file_llseek,
	.open = lkdtm_debugfs_open,
	.write = fs_devrw_entry} },
	{"MEM_SWAPOUT", {.read = lkdtm_debugfs_read,
	.llseek = generic_file_llseek,
	.open = lkdtm_debugfs_open,
	.write = mem_swapout_entry} },
	{"TIMERADD", {.read = lkdtm_debugfs_read,
	.llseek = generic_file_llseek,
	.open = lkdtm_debugfs_open,
	.write = timeradd_entry} },
	{"SCSI_DISPATCH_CMD", {.read = lkdtm_debugfs_read,
	.llseek = generic_file_llseek,
	.open = lkdtm_debugfs_open,
	.write = scsi_dispatch_cmd_entry} },
	{"IDE_CORE_CP", {.read = lkdtm_debugfs_read,
	.llseek = generic_file_llseek,
	.open = lkdtm_debugfs_open,
	.write = ide_core_cp_entry} },
	};

	static struct dentry *lkdtm_debugfs_root;

	static int __init lkdtm_module_init(void)
	{
	int ret = -EINVAL;
	int n_debugfs_entries = 1; /* Assume only the direct entry */
	int i;

	/* Register debugfs interface */
	lkdtm_debugfs_root = debugfs_create_dir("provoke-crash", NULL);
	if (!lkdtm_debugfs_root) {
	printk(KERN_ERR "lkdtm: creating root dir failed\n");
	return -ENODEV;
	}

	#ifdef CONFIG_KPROBES
	n_debugfs_entries = ARRAY_SIZE(crash_entries);
	#endif

	for (i = 0; i < n_debugfs_entries; i++) {
	const struct crash_entry *cur = &crash_entries[i];
	struct dentry *de;

	de = debugfs_create_file(cur->name, 0644, lkdtm_debugfs_root,
	NULL, &cur->fops);
	if (de == NULL) {
	printk(KERN_ERR "lkdtm: could not create %s\n",
	cur->name);
	goto out_err;
	}
	}

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

	if (cpoint != CN_INVALID && cptype != CT_NONE) {
	ret = lkdtm_register_cpoint(cpoint);
	if (ret < 0) {
	printk(KERN_INFO "lkdtm: Invalid crash point %d\n",
	cpoint);
	goto out_err;
	}
	printk(KERN_INFO "lkdtm: Crash point %s of type %s registered\n",
	cpoint_name, cpoint_type);
	} else {
	printk(KERN_INFO "lkdtm: No crash points registered, enable through debugfs\n");
	}

	return 0;

	out_err:
	debugfs_remove_recursive(lkdtm_debugfs_root);
	return ret;
	}

	static void __exit lkdtm_module_exit(void)
	{
	debugfs_remove_recursive(lkdtm_debugfs_root);

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

	module_init(lkdtm_module_init);
	module_exit(lkdtm_module_exit);

	MODULE_LICENSE("GPL");