lkdtm: split build into multiple source files

Kbuild lacks a way to do in-place objcopy or other modifications of
built targets, so in order to move functions into non-text sections
without renaming the kernel module, the build of lkdtm must be split
into separate source files. This renames lkdtm.c to lkdtm_core.c in
preparation for adding the source file for the .rodata section.

Signed-off-by: Kees Cook <keescook@chromium.org>

1 files changed, 1023 insertions, 0 deletions

diff --git a/drivers/misc/lkdtm_core.c b/drivers/misc/lkdtm_core.c
new file mode 100644
index 000000000000..0a5cbbe12452
--- /dev/null
+++ b/drivers/misc/lkdtm_core.c
@@ -0,0 +1,1023 @@
+/*
+ * 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
+ */
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#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>
+#include <linux/vmalloc.h>
+#include <linux/mman.h>
+#include <asm/cacheflush.h>
+
+#ifdef CONFIG_IDE
+#include <linux/ide.h>
+#endif
+
+/*
+ * Make sure our attempts to over run the kernel stack doesn't trigger
+ * a compiler warning when CONFIG_FRAME_WARN is set. Then make sure we
+ * recurse past the end of THREAD_SIZE by default.
+ */
+#if defined(CONFIG_FRAME_WARN) && (CONFIG_FRAME_WARN > 0)
+#define REC_STACK_SIZE (CONFIG_FRAME_WARN / 2)
+#else
+#define REC_STACK_SIZE (THREAD_SIZE / 8)
+#endif
+#define REC_NUM_DEFAULT ((THREAD_SIZE / REC_STACK_SIZE) * 2)
+
+#define DEFAULT_COUNT 10
+#define EXEC_SIZE 64
+
+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_WARNING,
+	CT_EXCEPTION,
+	CT_LOOP,
+	CT_OVERFLOW,
+	CT_CORRUPT_STACK,
+	CT_UNALIGNED_LOAD_STORE_WRITE,
+	CT_OVERWRITE_ALLOCATION,
+	CT_WRITE_AFTER_FREE,
+	CT_READ_AFTER_FREE,
+	CT_WRITE_BUDDY_AFTER_FREE,
+	CT_READ_BUDDY_AFTER_FREE,
+	CT_SOFTLOCKUP,
+	CT_HARDLOCKUP,
+	CT_SPINLOCKUP,
+	CT_HUNG_TASK,
+	CT_EXEC_DATA,
+	CT_EXEC_STACK,
+	CT_EXEC_KMALLOC,
+	CT_EXEC_VMALLOC,
+	CT_EXEC_USERSPACE,
+	CT_ACCESS_USERSPACE,
+	CT_WRITE_RO,
+	CT_WRITE_RO_AFTER_INIT,
+	CT_WRITE_KERN,
+	CT_WRAP_ATOMIC
+};
+
+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",
+	"WARNING",
+	"EXCEPTION",
+	"LOOP",
+	"OVERFLOW",
+	"CORRUPT_STACK",
+	"UNALIGNED_LOAD_STORE_WRITE",
+	"OVERWRITE_ALLOCATION",
+	"WRITE_AFTER_FREE",
+	"READ_AFTER_FREE",
+	"WRITE_BUDDY_AFTER_FREE",
+	"READ_BUDDY_AFTER_FREE",
+	"SOFTLOCKUP",
+	"HARDLOCKUP",
+	"SPINLOCKUP",
+	"HUNG_TASK",
+	"EXEC_DATA",
+	"EXEC_STACK",
+	"EXEC_KMALLOC",
+	"EXEC_VMALLOC",
+	"EXEC_USERSPACE",
+	"ACCESS_USERSPACE",
+	"WRITE_RO",
+	"WRITE_RO_AFTER_INIT",
+	"WRITE_KERN",
+	"WRAP_ATOMIC"
+};
+
+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);
+static DEFINE_SPINLOCK(lock_me_up);
+
+static u8 data_area[EXEC_SIZE];
+
+static const unsigned long rodata = 0xAA55AA55;
+static unsigned long ro_after_init __ro_after_init = 0x55AA5500;
+
+module_param(recur_count, int, 0644);
+MODULE_PARM_DESC(recur_count, " Recursion level for the stack overflow test");
+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
+static 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 remaining)
+{
+	char buf[REC_STACK_SIZE];
+
+	/* Make sure compiler does not optimize this away. */
+	memset(buf, (remaining & 0xff) | 0x1, REC_STACK_SIZE);
+	if (!remaining)
+		return 0;
+	else
+		return recursive_loop(remaining - 1);
+}
+
+static void do_nothing(void)
+{
+	return;
+}
+
+/* Must immediately follow do_nothing for size calculuations to work out. */
+static void do_overwritten(void)
+{
+	pr_info("do_overwritten wasn't overwritten!\n");
+	return;
+}
+
+static noinline void corrupt_stack(void)
+{
+	/* Use default char array length that triggers stack protection. */
+	char data[8];
+
+	memset((void *)data, 0, 64);
+}
+
+static void noinline execute_location(void *dst)
+{
+	void (*func)(void) = dst;
+
+	pr_info("attempting ok execution at %p\n", do_nothing);
+	do_nothing();
+
+	memcpy(dst, do_nothing, EXEC_SIZE);
+	flush_icache_range((unsigned long)dst, (unsigned long)dst + EXEC_SIZE);
+	pr_info("attempting bad execution at %p\n", func);
+	func();
+}
+
+static void execute_user_location(void *dst)
+{
+	/* Intentionally crossing kernel/user memory boundary. */
+	void (*func)(void) = dst;
+
+	pr_info("attempting ok execution at %p\n", do_nothing);
+	do_nothing();
+
+	if (copy_to_user((void __user *)dst, do_nothing, EXEC_SIZE))
+		return;
+	flush_icache_range((unsigned long)dst, (unsigned long)dst + EXEC_SIZE);
+	pr_info("attempting bad execution at %p\n", func);
+	func();
+}
+
+static void lkdtm_do_action(enum ctype which)
+{
+	switch (which) {
+	case CT_PANIC:
+		panic("dumptest");
+		break;
+	case CT_BUG:
+		BUG();
+		break;
+	case CT_WARNING:
+		WARN_ON(1);
+		break;
+	case CT_EXCEPTION:
+		*((int *) 0) = 0;
+		break;
+	case CT_LOOP:
+		for (;;)
+			;
+		break;
+	case CT_OVERFLOW:
+		(void) recursive_loop(recur_count);
+		break;
+	case CT_CORRUPT_STACK:
+		corrupt_stack();
+		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: {
+		int *base, *again;
+		size_t len = 1024;
+		/*
+		 * The slub allocator uses the first word to store the free
+		 * pointer in some configurations. Use the middle of the
+		 * allocation to avoid running into the freelist
+		 */
+		size_t offset = (len / sizeof(*base)) / 2;
+
+		base = kmalloc(len, GFP_KERNEL);
+		pr_info("Allocated memory %p-%p\n", base, &base[offset * 2]);
+		pr_info("Attempting bad write to freed memory at %p\n",
+			&base[offset]);
+		kfree(base);
+		base[offset] = 0x0abcdef0;
+		/* Attempt to notice the overwrite. */
+		again = kmalloc(len, GFP_KERNEL);
+		kfree(again);
+		if (again != base)
+			pr_info("Hmm, didn't get the same memory range.\n");
+
+		break;
+	}
+	case CT_READ_AFTER_FREE: {
+		int *base, *val, saw;
+		size_t len = 1024;
+		/*
+		 * The slub allocator uses the first word to store the free
+		 * pointer in some configurations. Use the middle of the
+		 * allocation to avoid running into the freelist
+		 */
+		size_t offset = (len / sizeof(*base)) / 2;
+
+		base = kmalloc(len, GFP_KERNEL);
+		if (!base)
+			break;
+
+		val = kmalloc(len, GFP_KERNEL);
+		if (!val) {
+			kfree(base);
+			break;
+		}
+
+		*val = 0x12345678;
+		base[offset] = *val;
+		pr_info("Value in memory before free: %x\n", base[offset]);
+
+		kfree(base);
+
+		pr_info("Attempting bad read from freed memory\n");
+		saw = base[offset];
+		if (saw != *val) {
+			/* Good! Poisoning happened, so declare a win. */
+			pr_info("Memory correctly poisoned (%x)\n", saw);
+			BUG();
+		}
+		pr_info("Memory was not poisoned\n");
+
+		kfree(val);
+		break;
+	}
+	case CT_WRITE_BUDDY_AFTER_FREE: {
+		unsigned long p = __get_free_page(GFP_KERNEL);
+		if (!p)
+			break;
+		pr_info("Writing to the buddy page before free\n");
+		memset((void *)p, 0x3, PAGE_SIZE);
+		free_page(p);
+		schedule();
+		pr_info("Attempting bad write to the buddy page after free\n");
+		memset((void *)p, 0x78, PAGE_SIZE);
+		/* Attempt to notice the overwrite. */
+		p = __get_free_page(GFP_KERNEL);
+		free_page(p);
+		schedule();
+
+		break;
+	}
+	case CT_READ_BUDDY_AFTER_FREE: {
+		unsigned long p = __get_free_page(GFP_KERNEL);
+		int saw, *val;
+		int *base;
+
+		if (!p)
+			break;
+
+		val = kmalloc(1024, GFP_KERNEL);
+		if (!val) {
+			free_page(p);
+			break;
+		}
+
+		base = (int *)p;
+
+		*val = 0x12345678;
+		base[0] = *val;
+		pr_info("Value in memory before free: %x\n", base[0]);
+		free_page(p);
+		pr_info("Attempting to read from freed memory\n");
+		saw = base[0];
+		if (saw != *val) {
+			/* Good! Poisoning happened, so declare a win. */
+			pr_info("Memory correctly poisoned (%x)\n", saw);
+			BUG();
+		}
+		pr_info("Buddy page was not poisoned\n");
+
+		kfree(val);
+		break;
+	}
+	case CT_SOFTLOCKUP:
+		preempt_disable();
+		for (;;)
+			cpu_relax();
+		break;
+	case CT_HARDLOCKUP:
+		local_irq_disable();
+		for (;;)
+			cpu_relax();
+		break;
+	case CT_SPINLOCKUP:
+		/* Must be called twice to trigger. */
+		spin_lock(&lock_me_up);
+		/* Let sparse know we intended to exit holding the lock. */
+		__release(&lock_me_up);
+		break;
+	case CT_HUNG_TASK:
+		set_current_state(TASK_UNINTERRUPTIBLE);
+		schedule();
+		break;
+	case CT_EXEC_DATA:
+		execute_location(data_area);
+		break;
+	case CT_EXEC_STACK: {
+		u8 stack_area[EXEC_SIZE];
+		execute_location(stack_area);
+		break;
+	}
+	case CT_EXEC_KMALLOC: {
+		u32 *kmalloc_area = kmalloc(EXEC_SIZE, GFP_KERNEL);
+		execute_location(kmalloc_area);
+		kfree(kmalloc_area);
+		break;
+	}
+	case CT_EXEC_VMALLOC: {
+		u32 *vmalloc_area = vmalloc(EXEC_SIZE);
+		execute_location(vmalloc_area);
+		vfree(vmalloc_area);
+		break;
+	}
+	case CT_EXEC_USERSPACE: {
+		unsigned long user_addr;
+
+		user_addr = vm_mmap(NULL, 0, PAGE_SIZE,
+				    PROT_READ | PROT_WRITE | PROT_EXEC,
+				    MAP_ANONYMOUS | MAP_PRIVATE, 0);
+		if (user_addr >= TASK_SIZE) {
+			pr_warn("Failed to allocate user memory\n");
+			return;
+		}
+		execute_user_location((void *)user_addr);
+		vm_munmap(user_addr, PAGE_SIZE);
+		break;
+	}
+	case CT_ACCESS_USERSPACE: {
+		unsigned long user_addr, tmp = 0;
+		unsigned long *ptr;
+
+		user_addr = vm_mmap(NULL, 0, PAGE_SIZE,
+				    PROT_READ | PROT_WRITE | PROT_EXEC,
+				    MAP_ANONYMOUS | MAP_PRIVATE, 0);
+		if (user_addr >= TASK_SIZE) {
+			pr_warn("Failed to allocate user memory\n");
+			return;
+		}
+
+		if (copy_to_user((void __user *)user_addr, &tmp, sizeof(tmp))) {
+			pr_warn("copy_to_user failed\n");
+			vm_munmap(user_addr, PAGE_SIZE);
+			return;
+		}
+
+		ptr = (unsigned long *)user_addr;
+
+		pr_info("attempting bad read at %p\n", ptr);
+		tmp = *ptr;
+		tmp += 0xc0dec0de;
+
+		pr_info("attempting bad write at %p\n", ptr);
+		*ptr = tmp;
+
+		vm_munmap(user_addr, PAGE_SIZE);
+
+		break;
+	}
+	case CT_WRITE_RO: {
+		/* Explicitly cast away "const" for the test. */
+		unsigned long *ptr = (unsigned long *)&rodata;
+
+		pr_info("attempting bad rodata write at %p\n", ptr);
+		*ptr ^= 0xabcd1234;
+
+		break;
+	}
+	case CT_WRITE_RO_AFTER_INIT: {
+		unsigned long *ptr = &ro_after_init;
+
+		/*
+		 * Verify we were written to during init. Since an Oops
+		 * is considered a "success", a failure is to just skip the
+		 * real test.
+		 */
+		if ((*ptr & 0xAA) != 0xAA) {
+			pr_info("%p was NOT written during init!?\n", ptr);
+			break;
+		}
+
+		pr_info("attempting bad ro_after_init write at %p\n", ptr);
+		*ptr ^= 0xabcd1234;
+
+		break;
+	}
+	case CT_WRITE_KERN: {
+		size_t size;
+		unsigned char *ptr;
+
+		size = (unsigned long)do_overwritten -
+		       (unsigned long)do_nothing;
+		ptr = (unsigned char *)do_overwritten;
+
+		pr_info("attempting bad %zu byte write at %p\n", size, ptr);
+		memcpy(ptr, (unsigned char *)do_nothing, size);
+		flush_icache_range((unsigned long)ptr,
+				   (unsigned long)(ptr + size));
+
+		do_overwritten();
+		break;
+	}
+	case CT_WRAP_ATOMIC: {
+		atomic_t under = ATOMIC_INIT(INT_MIN);
+		atomic_t over = ATOMIC_INIT(INT_MAX);
+
+		pr_info("attempting atomic underflow\n");
+		atomic_dec(&under);
+		pr_info("attempting atomic overflow\n");
+		atomic_inc(&over);
+
+		return;
+	}
+	case CT_NONE:
+	default:
+		break;
+	}
+
+}
+
+static void lkdtm_handler(void)
+{
+	unsigned long flags;
+	bool do_it = false;
+
+	spin_lock_irqsave(&count_lock, flags);
+	count--;
+	pr_info("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
+		pr_info("Crash point not available\n");
+		return -EINVAL;
+#endif
+		break;
+	default:
+		pr_info("Invalid Crash Point\n");
+		return -EINVAL;
+	}
+
+	cpoint = which;
+	if ((ret = register_jprobe(&lkdtm)) < 0) {
+		pr_info("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;
+
+	pr_info("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;
+
+	/* Make sure we can write to __ro_after_init values during __init */
+	ro_after_init |= 0xAA;
+
+	/* Register debugfs interface */
+	lkdtm_debugfs_root = debugfs_create_dir("provoke-crash", NULL);
+	if (!lkdtm_debugfs_root) {
+		pr_err("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) {
+			pr_err("could not create %s\n", cur->name);
+			goto out_err;
+		}
+	}
+
+	if (lkdtm_parse_commandline() == -EINVAL) {
+		pr_info("Invalid command\n");
+		goto out_err;
+	}
+
+	if (cpoint != CN_INVALID && cptype != CT_NONE) {
+		ret = lkdtm_register_cpoint(cpoint);
+		if (ret < 0) {
+			pr_info("Invalid crash point %d\n", cpoint);
+			goto out_err;
+		}
+		pr_info("Crash point %s of type %s registered\n",
+			cpoint_name, cpoint_type);
+	} else {
+		pr_info("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);
+	pr_info("Crash point unregistered\n");
+}
+
+module_init(lkdtm_module_init);
+module_exit(lkdtm_module_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Kprobe module for testing crash dumps");