lkdtm.c

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/*
 * 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 <[email protected]>
 *
 * 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 <[email protected]>
 *
 * 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");