/*
   * 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;
  
  	spin_lock_irqsave(&count_lock, flags);

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

  
  	if (count == 0) {

  		lkdtm_do_action(cptype);

  		count = cpoint_count;
  	}

  	spin_unlock_irqrestore(&count_lock, flags);

  }

  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
  ");
  		return -EINVAL;

  #endif
  		break;
  	default:

  		printk(KERN_INFO "lkdtm: Invalid Crash Point
  ");
  		return -EINVAL;

  	}

  	cpoint = which;

  	if ((ret = register_jprobe(&lkdtm)) < 0) {

  		printk(KERN_INFO "lkdtm: Couldn't register jprobe
  ");

  		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);
  
  	n = snprintf(buf, PAGE_SIZE, "Available crash types:
  ");
  	for (i = 0; i < ARRAY_SIZE(cp_type); i++)
  		n += snprintf(buf + n, PAGE_SIZE - n, "%s
  ", 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
  ",
  			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
  ");
  		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
  ",
  					cur->name);
  			goto out_err;
  		}
  	}
  
  	if (lkdtm_parse_commandline() == -EINVAL) {
  		printk(KERN_INFO "lkdtm: Invalid command
  ");
  		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
  ",
  					cpoint);
  			goto out_err;
  		}
  		printk(KERN_INFO "lkdtm: Crash point %s of type %s registered
  ",
  				cpoint_name, cpoint_type);
  	} else {
  		printk(KERN_INFO "lkdtm: No crash points registered, enable through debugfs
  ");

  	}

  	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
  ");

  }
  
  module_init(lkdtm_module_init);
  module_exit(lkdtm_module_exit);
  
  MODULE_LICENSE("GPL");