[RFC] Linux Kernel Dump Test Module

[Ankita Garg <ankita@in.ibm.com>]

Hi,

Please find below a patch for a simple module to test Linux Kernel Dump 
mechanism. This module uses jprobes to install/activate pre-defined crash
points. At different crash points, various types of crashing scenarios 
are created like a BUG(), panic(), exception, recursive loop and stack 
overflow. The user can activate a crash point with specific type by
providing parameters at the time of module insertion. Please see the file
header for usage information. The module is based on the Linux Kernel
Dump Test Tool by Fernando <http://lkdtt.sourceforge.net>.

This module could be merged with mainline. Jprobes is used here so that the 
context in which crash point is hit, could be maintained. This implements
all the crash points as done by LKDTT except the one in the middle of 
tasklet_action(). 


Please review and comment.

Thanks
Ankita


o This patch implements the Linux Kernel Dump Test Module, to test Linux 
  kernel crashdumping mechanisms. The detailed usage information is in
  drivers/misc/lkdtm.c


Signed-off-by: Ankita Garg <ankita@in.ibm.com>
--
 drivers/misc/Makefile |    1
 drivers/misc/lkdtm.c  |  334 ++++++++++++++++++++++++++++++++++++++++++++++++++ lib/Kconfig.debug     |   14 ++
 3 files changed, 349 insertions(+)

Index: linux-2.6.18-rc5/lib/Kconfig.debug
===================================================================
--- linux-2.6.18-rc5.orig/lib/Kconfig.debug	2006-09-07 10:32:15.000000000 +0530
+++ linux-2.6.18-rc5/lib/Kconfig.debug	2006-09-07 10:52:22.000000000 +0530
@@ -429,3 +429,17 @@
 	  at boot time (you probably don't).
 	  Say M if you want the RCU torture tests to build as a module.
 	  Say N if you are unsure.
+
+config LKDTM
+	tristate "Linux Kernel Dump Test Tool Module"
+	depends on KPROBES
+	default n
+	help
+	This module enables testing of the different dumping mechanisms by
+	inducing system failures at predefined crash points.
+	If you don't need it: say N
+	Choose M here to compile this code as a module. The module will be
+	called lkdtm.
+
+	Documentation on how to use the module can be found in
+	drivers/misc/lkdtm.c
Index: linux-2.6.18-rc5/drivers/misc/Makefile
===================================================================
--- linux-2.6.18-rc5.orig/drivers/misc/Makefile	2006-08-28 09:11:48.000000000 +0530
+++ linux-2.6.18-rc5/drivers/misc/Makefile	2006-09-07 10:43:41.000000000 +0530
@@ -5,3 +5,4 @@
 
 obj-$(CONFIG_IBM_ASM)	+= ibmasm/
 obj-$(CONFIG_HDPU_FEATURES)	+= hdpuftrs/
+obj-$(CONFIG_LKDTM)	+= lkdtm.o
Index: linux-2.6.18-rc5/drivers/misc/lkdtm.c
===================================================================
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ linux-2.6.18-rc5/drivers/misc/lkdtm.c	2006-09-07 10:48:52.000000000 +0530
@@ -0,0 +1,334 @@
+/*
+ * 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/module.h>
+#include<linux/kprobes.h>
+#include<linux/kallsyms.h>
+#include<linux/init.h>
+#include<linux/irq.h>
+#include<linux/ide.h>
+#include<linux/interrupt.h>
+#include<scsi/scsi_cmnd.h>
+
+#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 = INVALID;
+static char* cpoint_type = NONE;
+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, "Recurcion 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, 06444);
+MODULE_PARM_DESC(cpoint_type, "Crash Point Type, action to be taken on\
+				hitting the crash point");
+module_param(cpoint_count, int, 06444);
+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, struct pt_regs *regs)
+{
+	lkdtm_handler();
+	jprobe_return();
+	return 0;
+}
+
+irqreturn_t jp_handle_irq_event(unsigned int irq, struct pt_regs *regs,
+			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_page_list(struct list_head *page_list,
+                                        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;
+}
+
+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;
+}
+
+
+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_page_list";
+		lkdtm.entry = (kprobe_opcode_t*) jp_shrink_page_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:
+		lkdtm.kp.symbol_name = "generic_ide_ioctl";
+		lkdtm.entry = (kprobe_opcode_t*) jp_generic_ide_ioctl;
+		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");
-
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