drivers/misc/lkdtm.c

   1 /*
   2  * Kprobe module for testing crash dumps
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation; either version 2 of the License, or
   7  * (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write to the Free Software
  16  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  17  *
  18  * Copyright (C) IBM Corporation, 2006
  19  *
  20  * Author: Ankita Garg <ankita@in.ibm.com>
  21  *
  22  * This module induces system failures at predefined crashpoints to
  23  * evaluate the reliability of crash dumps obtained using different dumping
  24  * solutions.
  25  *
  26  * It is adapted from the Linux Kernel Dump Test Tool by
  27  * Fernando Luis Vazquez Cao <http://lkdtt.sourceforge.net>
  28  *
  29  * Debugfs support added by Simon Kagstrom <simon.kagstrom@netinsight.net>
  30  *
  31  * See Documentation/fault-injection/provoke-crashes.txt for instructions
  32  */
  33 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  34
  35 #include <linux/kernel.h>
  36 #include <linux/fs.h>
  37 #include <linux/module.h>
  38 #include <linux/buffer_head.h>
  39 #include <linux/kprobes.h>
  40 #include <linux/list.h>
  41 #include <linux/init.h>
  42 #include <linux/interrupt.h>
  43 #include <linux/hrtimer.h>
  44 #include <linux/slab.h>
  45 #include <scsi/scsi_cmnd.h>
  46 #include <linux/debugfs.h>
  47 #include <linux/vmalloc.h>
  48 #include <linux/mman.h>
  49
  50 #ifdef CONFIG_IDE
  51 #include <linux/ide.h>
  52 #endif
  53
  54 /*
  55  * Make sure our attempts to over run the kernel stack doesn't trigger
  56  * a compiler warning when CONFIG_FRAME_WARN is set. Then make sure we
  57  * recurse past the end of THREAD_SIZE by default.
  58  */
  59 #if defined(CONFIG_FRAME_WARN) && (CONFIG_FRAME_WARN > 0)
  60 #define REC_STACK_SIZE (CONFIG_FRAME_WARN / 2)
  61 #else
  62 #define REC_STACK_SIZE (THREAD_SIZE / 8)
  63 #endif
  64 #define REC_NUM_DEFAULT ((THREAD_SIZE / REC_STACK_SIZE) * 2)
  65
  66 #define DEFAULT_COUNT 10
  67 #define EXEC_SIZE 64
  68
  69 enum cname {
  70         CN_INVALID,
  71         CN_INT_HARDWARE_ENTRY,
  72         CN_INT_HW_IRQ_EN,
  73         CN_INT_TASKLET_ENTRY,
  74         CN_FS_DEVRW,
  75         CN_MEM_SWAPOUT,
  76         CN_TIMERADD,
  77         CN_SCSI_DISPATCH_CMD,
  78         CN_IDE_CORE_CP,
  79         CN_DIRECT,
  80 };
  81
  82 enum ctype {
  83         CT_NONE,
  84         CT_PANIC,
  85         CT_BUG,
  86         CT_WARNING,
  87         CT_EXCEPTION,
  88         CT_LOOP,
  89         CT_OVERFLOW,
  90         CT_CORRUPT_STACK,
  91         CT_UNALIGNED_LOAD_STORE_WRITE,
  92         CT_OVERWRITE_ALLOCATION,
  93         CT_WRITE_AFTER_FREE,
  94         CT_SOFTLOCKUP,
  95         CT_HARDLOCKUP,
  96         CT_SPINLOCKUP,
  97         CT_HUNG_TASK,
  98         CT_EXEC_DATA,
  99         CT_EXEC_STACK,
 100         CT_EXEC_KMALLOC,
 101         CT_EXEC_VMALLOC,
 102         CT_EXEC_USERSPACE,
 103         CT_ACCESS_USERSPACE,
 104         CT_WRITE_RO,
 105 };
 106
 107 static char* cp_name[] = {
 108         "INT_HARDWARE_ENTRY",
 109         "INT_HW_IRQ_EN",
 110         "INT_TASKLET_ENTRY",
 111         "FS_DEVRW",
 112         "MEM_SWAPOUT",
 113         "TIMERADD",
 114         "SCSI_DISPATCH_CMD",
 115         "IDE_CORE_CP",
 116         "DIRECT",
 117 };
 118
 119 static char* cp_type[] = {
 120         "PANIC",
 121         "BUG",
 122         "WARNING",
 123         "EXCEPTION",
 124         "LOOP",
 125         "OVERFLOW",
 126         "CORRUPT_STACK",
 127         "UNALIGNED_LOAD_STORE_WRITE",
 128         "OVERWRITE_ALLOCATION",
 129         "WRITE_AFTER_FREE",
 130         "SOFTLOCKUP",
 131         "HARDLOCKUP",
 132         "SPINLOCKUP",
 133         "HUNG_TASK",
 134         "EXEC_DATA",
 135         "EXEC_STACK",
 136         "EXEC_KMALLOC",
 137         "EXEC_VMALLOC",
 138         "EXEC_USERSPACE",
 139         "ACCESS_USERSPACE",
 140         "WRITE_RO",
 141 };
 142
 143 static struct jprobe lkdtm;
 144
 145 static int lkdtm_parse_commandline(void);
 146 static void lkdtm_handler(void);
 147
 148 static char* cpoint_name;
 149 static char* cpoint_type;
 150 static int cpoint_count = DEFAULT_COUNT;
 151 static int recur_count = REC_NUM_DEFAULT;
 152
 153 static enum cname cpoint = CN_INVALID;
 154 static enum ctype cptype = CT_NONE;
 155 static int count = DEFAULT_COUNT;
 156 static DEFINE_SPINLOCK(count_lock);
 157 static DEFINE_SPINLOCK(lock_me_up);
 158
 159 static u8 data_area[EXEC_SIZE];
 160
 161 static const unsigned long rodata = 0xAA55AA55;
 162
 163 module_param(recur_count, int, 0644);
 164 MODULE_PARM_DESC(recur_count, " Recursion level for the stack overflow test");
 165 module_param(cpoint_name, charp, 0444);
 166 MODULE_PARM_DESC(cpoint_name, " Crash Point, where kernel is to be crashed");
 167 module_param(cpoint_type, charp, 0444);
 168 MODULE_PARM_DESC(cpoint_type, " Crash Point Type, action to be taken on "\
 169                                 "hitting the crash point");
 170 module_param(cpoint_count, int, 0644);
 171 MODULE_PARM_DESC(cpoint_count, " Crash Point Count, number of times the "\
 172                                 "crash point is to be hit to trigger action");
 173
 174 static unsigned int jp_do_irq(unsigned int irq)
 175 {
 176         lkdtm_handler();
 177         jprobe_return();
 178         return 0;
 179 }
 180
 181 static irqreturn_t jp_handle_irq_event(unsigned int irq,
 182                                        struct irqaction *action)
 183 {
 184         lkdtm_handler();
 185         jprobe_return();
 186         return 0;
 187 }
 188
 189 static void jp_tasklet_action(struct softirq_action *a)
 190 {
 191         lkdtm_handler();
 192         jprobe_return();
 193 }
 194
 195 static void jp_ll_rw_block(int rw, int nr, struct buffer_head *bhs[])
 196 {
 197         lkdtm_handler();
 198         jprobe_return();
 199 }
 200
 201 struct scan_control;
 202
 203 static unsigned long jp_shrink_inactive_list(unsigned long max_scan,
 204                                              struct zone *zone,
 205                                              struct scan_control *sc)
 206 {
 207         lkdtm_handler();
 208         jprobe_return();
 209         return 0;
 210 }
 211
 212 static int jp_hrtimer_start(struct hrtimer *timer, ktime_t tim,
 213                             const enum hrtimer_mode mode)
 214 {
 215         lkdtm_handler();
 216         jprobe_return();
 217         return 0;
 218 }
 219
 220 static int jp_scsi_dispatch_cmd(struct scsi_cmnd *cmd)
 221 {
 222         lkdtm_handler();
 223         jprobe_return();
 224         return 0;
 225 }
 226
 227 #ifdef CONFIG_IDE
 228 static int jp_generic_ide_ioctl(ide_drive_t *drive, struct file *file,
 229                         struct block_device *bdev, unsigned int cmd,
 230                         unsigned long arg)
 231 {
 232         lkdtm_handler();
 233         jprobe_return();
 234         return 0;
 235 }
 236 #endif
 237
 238 /* Return the crashpoint number or NONE if the name is invalid */
 239 static enum ctype parse_cp_type(const char *what, size_t count)
 240 {
 241         int i;
 242
 243         for (i = 0; i < ARRAY_SIZE(cp_type); i++) {
 244                 if (!strcmp(what, cp_type[i]))
 245                         return i + 1;
 246         }
 247
 248         return CT_NONE;
 249 }
 250
 251 static const char *cp_type_to_str(enum ctype type)
 252 {
 253         if (type == CT_NONE || type < 0 || type > ARRAY_SIZE(cp_type))
 254                 return "None";
 255
 256         return cp_type[type - 1];
 257 }
 258
 259 static const char *cp_name_to_str(enum cname name)
 260 {
 261         if (name == CN_INVALID || name < 0 || name > ARRAY_SIZE(cp_name))
 262                 return "INVALID";
 263
 264         return cp_name[name - 1];
 265 }
 266
 267
 268 static int lkdtm_parse_commandline(void)
 269 {
 270         int i;
 271         unsigned long flags;
 272
 273         if (cpoint_count < 1 || recur_count < 1)
 274                 return -EINVAL;
 275
 276         spin_lock_irqsave(&count_lock, flags);
 277         count = cpoint_count;
 278         spin_unlock_irqrestore(&count_lock, flags);
 279
 280         /* No special parameters */
 281         if (!cpoint_type && !cpoint_name)
 282                 return 0;
 283
 284         /* Neither or both of these need to be set */
 285         if (!cpoint_type || !cpoint_name)
 286                 return -EINVAL;
 287
 288         cptype = parse_cp_type(cpoint_type, strlen(cpoint_type));
 289         if (cptype == CT_NONE)
 290                 return -EINVAL;
 291
 292         for (i = 0; i < ARRAY_SIZE(cp_name); i++) {
 293                 if (!strcmp(cpoint_name, cp_name[i])) {
 294                         cpoint = i + 1;
 295                         return 0;
 296                 }
 297         }
 298
 299         /* Could not find a valid crash point */
 300         return -EINVAL;
 301 }
 302
 303 static int recursive_loop(int remaining)
 304 {
 305         char buf[REC_STACK_SIZE];
 306
 307         /* Make sure compiler does not optimize this away. */
 308         memset(buf, (remaining & 0xff) | 0x1, REC_STACK_SIZE);
 309         if (!remaining)
 310                 return 0;
 311         else
 312                 return recursive_loop(remaining - 1);
 313 }
 314
 315 static void do_nothing(void)
 316 {
 317         return;
 318 }
 319
 320 static noinline void corrupt_stack(void)
 321 {
 322         /* Use default char array length that triggers stack protection. */
 323         char data[8];
 324
 325         memset((void *)data, 0, 64);
 326 }
 327
 328 static void execute_location(void *dst)
 329 {
 330         void (*func)(void) = dst;
 331
 332         memcpy(dst, do_nothing, EXEC_SIZE);
 333         func();
 334 }
 335
 336 static void execute_user_location(void *dst)
 337 {
 338         /* Intentionally crossing kernel/user memory boundary. */
 339         void (*func)(void) = dst;
 340
 341         if (copy_to_user((void __user *)dst, do_nothing, EXEC_SIZE))
 342                 return;
 343         func();
 344 }
 345
 346 static void lkdtm_do_action(enum ctype which)
 347 {
 348         switch (which) {
 349         case CT_PANIC:
 350                 panic("dumptest");
 351                 break;
 352         case CT_BUG:
 353                 BUG();
 354                 break;
 355         case CT_WARNING:
 356                 WARN_ON(1);
 357                 break;
 358         case CT_EXCEPTION:
 359                 *((int *) 0) = 0;
 360                 break;
 361         case CT_LOOP:
 362                 for (;;)
 363                         ;
 364                 break;
 365         case CT_OVERFLOW:
 366                 (void) recursive_loop(recur_count);
 367                 break;
 368         case CT_CORRUPT_STACK:
 369                 corrupt_stack();
 370                 break;
 371         case CT_UNALIGNED_LOAD_STORE_WRITE: {
 372                 static u8 data[5] __attribute__((aligned(4))) = {1, 2,
 373                                 3, 4, 5};
 374                 u32 *p;
 375                 u32 val = 0x12345678;
 376
 377                 p = (u32 *)(data + 1);
 378                 if (*p == 0)
 379                         val = 0x87654321;
 380                 *p = val;
 381                  break;
 382         }
 383         case CT_OVERWRITE_ALLOCATION: {
 384                 size_t len = 1020;
 385                 u32 *data = kmalloc(len, GFP_KERNEL);
 386
 387                 data[1024 / sizeof(u32)] = 0x12345678;
 388                 kfree(data);
 389                 break;
 390         }
 391         case CT_WRITE_AFTER_FREE: {
 392                 size_t len = 1024;
 393                 u32 *data = kmalloc(len, GFP_KERNEL);
 394
 395                 kfree(data);
 396                 schedule();
 397                 memset(data, 0x78, len);
 398                 break;
 399         }
 400         case CT_SOFTLOCKUP:
 401                 preempt_disable();
 402                 for (;;)
 403                         cpu_relax();
 404                 break;
 405         case CT_HARDLOCKUP:
 406                 local_irq_disable();
 407                 for (;;)
 408                         cpu_relax();
 409                 break;
 410         case CT_SPINLOCKUP:
 411                 /* Must be called twice to trigger. */
 412                 spin_lock(&lock_me_up);
 413                 /* Let sparse know we intended to exit holding the lock. */
 414                 __release(&lock_me_up);
 415                 break;
 416         case CT_HUNG_TASK:
 417                 set_current_state(TASK_UNINTERRUPTIBLE);
 418                 schedule();
 419                 break;
 420         case CT_EXEC_DATA:
 421                 execute_location(data_area);
 422                 break;
 423         case CT_EXEC_STACK: {
 424                 u8 stack_area[EXEC_SIZE];
 425                 execute_location(stack_area);
 426                 break;
 427         }
 428         case CT_EXEC_KMALLOC: {
 429                 u32 *kmalloc_area = kmalloc(EXEC_SIZE, GFP_KERNEL);
 430                 execute_location(kmalloc_area);
 431                 kfree(kmalloc_area);
 432                 break;
 433         }
 434         case CT_EXEC_VMALLOC: {
 435                 u32 *vmalloc_area = vmalloc(EXEC_SIZE);
 436                 execute_location(vmalloc_area);
 437                 vfree(vmalloc_area);
 438                 break;
 439         }
 440         case CT_EXEC_USERSPACE: {
 441                 unsigned long user_addr;
 442
 443                 user_addr = vm_mmap(NULL, 0, PAGE_SIZE,
 444                                     PROT_READ | PROT_WRITE | PROT_EXEC,
 445                                     MAP_ANONYMOUS | MAP_PRIVATE, 0);
 446                 if (user_addr >= TASK_SIZE) {
 447                         pr_warn("Failed to allocate user memory\n");
 448                         return;
 449                 }
 450                 execute_user_location((void *)user_addr);
 451                 vm_munmap(user_addr, PAGE_SIZE);
 452                 break;
 453         }
 454         case CT_ACCESS_USERSPACE: {
 455                 unsigned long user_addr, tmp;
 456                 unsigned long *ptr;
 457
 458                 user_addr = vm_mmap(NULL, 0, PAGE_SIZE,
 459                                     PROT_READ | PROT_WRITE | PROT_EXEC,
 460                                     MAP_ANONYMOUS | MAP_PRIVATE, 0);
 461                 if (user_addr >= TASK_SIZE) {
 462                         pr_warn("Failed to allocate user memory\n");
 463                         return;
 464                 }
 465
 466                 ptr = (unsigned long *)user_addr;
 467                 tmp = *ptr;
 468                 tmp += 0xc0dec0de;
 469                 *ptr = tmp;
 470
 471                 vm_munmap(user_addr, PAGE_SIZE);
 472
 473                 break;
 474         }
 475         case CT_WRITE_RO: {
 476                 unsigned long *ptr;
 477
 478                 ptr = (unsigned long *)&rodata;
 479                 *ptr ^= 0xabcd1234;
 480
 481                 break;
 482         }
 483         case CT_NONE:
 484         default:
 485                 break;
 486         }
 487
 488 }
 489
 490 static void lkdtm_handler(void)
 491 {
 492         unsigned long flags;
 493         bool do_it = false;
 494
 495         spin_lock_irqsave(&count_lock, flags);
 496         count--;
 497         pr_info("Crash point %s of type %s hit, trigger in %d rounds\n",
 498                 cp_name_to_str(cpoint), cp_type_to_str(cptype), count);
 499
 500         if (count == 0) {
 501                 do_it = true;
 502                 count = cpoint_count;
 503         }
 504         spin_unlock_irqrestore(&count_lock, flags);
 505
 506         if (do_it)
 507                 lkdtm_do_action(cptype);
 508 }
 509
 510 static int lkdtm_register_cpoint(enum cname which)
 511 {
 512         int ret;
 513
 514         cpoint = CN_INVALID;
 515         if (lkdtm.entry != NULL)
 516                 unregister_jprobe(&lkdtm);
 517
 518         switch (which) {
 519         case CN_DIRECT:
 520                 lkdtm_do_action(cptype);
 521                 return 0;
 522         case CN_INT_HARDWARE_ENTRY:
 523                 lkdtm.kp.symbol_name = "do_IRQ";
 524                 lkdtm.entry = (kprobe_opcode_t*) jp_do_irq;
 525                 break;
 526         case CN_INT_HW_IRQ_EN:
 527                 lkdtm.kp.symbol_name = "handle_IRQ_event";
 528                 lkdtm.entry = (kprobe_opcode_t*) jp_handle_irq_event;
 529                 break;
 530         case CN_INT_TASKLET_ENTRY:
 531                 lkdtm.kp.symbol_name = "tasklet_action";
 532                 lkdtm.entry = (kprobe_opcode_t*) jp_tasklet_action;
 533                 break;
 534         case CN_FS_DEVRW:
 535                 lkdtm.kp.symbol_name = "ll_rw_block";
 536                 lkdtm.entry = (kprobe_opcode_t*) jp_ll_rw_block;
 537                 break;
 538         case CN_MEM_SWAPOUT:
 539                 lkdtm.kp.symbol_name = "shrink_inactive_list";
 540                 lkdtm.entry = (kprobe_opcode_t*) jp_shrink_inactive_list;
 541                 break;
 542         case CN_TIMERADD:
 543                 lkdtm.kp.symbol_name = "hrtimer_start";
 544                 lkdtm.entry = (kprobe_opcode_t*) jp_hrtimer_start;
 545                 break;
 546         case CN_SCSI_DISPATCH_CMD:
 547                 lkdtm.kp.symbol_name = "scsi_dispatch_cmd";
 548                 lkdtm.entry = (kprobe_opcode_t*) jp_scsi_dispatch_cmd;
 549                 break;
 550         case CN_IDE_CORE_CP:
 551 #ifdef CONFIG_IDE
 552                 lkdtm.kp.symbol_name = "generic_ide_ioctl";
 553                 lkdtm.entry = (kprobe_opcode_t*) jp_generic_ide_ioctl;
 554 #else
 555                 pr_info("Crash point not available\n");
 556                 return -EINVAL;
 557 #endif
 558                 break;
 559         default:
 560                 pr_info("Invalid Crash Point\n");
 561                 return -EINVAL;
 562         }
 563
 564         cpoint = which;
 565         if ((ret = register_jprobe(&lkdtm)) < 0) {
 566                 pr_info("Couldn't register jprobe\n");
 567                 cpoint = CN_INVALID;
 568         }
 569
 570         return ret;
 571 }
 572
 573 static ssize_t do_register_entry(enum cname which, struct file *f,
 574                 const char __user *user_buf, size_t count, loff_t *off)
 575 {
 576         char *buf;
 577         int err;
 578
 579         if (count >= PAGE_SIZE)
 580                 return -EINVAL;
 581
 582         buf = (char *)__get_free_page(GFP_KERNEL);
 583         if (!buf)
 584                 return -ENOMEM;
 585         if (copy_from_user(buf, user_buf, count)) {
 586                 free_page((unsigned long) buf);
 587                 return -EFAULT;
 588         }
 589         /* NULL-terminate and remove enter */
 590         buf[count] = '\0';
 591         strim(buf);
 592
 593         cptype = parse_cp_type(buf, count);
 594         free_page((unsigned long) buf);
 595
 596         if (cptype == CT_NONE)
 597                 return -EINVAL;
 598
 599         err = lkdtm_register_cpoint(which);
 600         if (err < 0)
 601                 return err;
 602
 603         *off += count;
 604
 605         return count;
 606 }
 607
 608 /* Generic read callback that just prints out the available crash types */
 609 static ssize_t lkdtm_debugfs_read(struct file *f, char __user *user_buf,
 610                 size_t count, loff_t *off)
 611 {
 612         char *buf;
 613         int i, n, out;
 614
 615         buf = (char *)__get_free_page(GFP_KERNEL);
 616         if (buf == NULL)
 617                 return -ENOMEM;
 618
 619         n = snprintf(buf, PAGE_SIZE, "Available crash types:\n");
 620         for (i = 0; i < ARRAY_SIZE(cp_type); i++)
 621                 n += snprintf(buf + n, PAGE_SIZE - n, "%s\n", cp_type[i]);
 622         buf[n] = '\0';
 623
 624         out = simple_read_from_buffer(user_buf, count, off,
 625                                       buf, n);
 626         free_page((unsigned long) buf);
 627
 628         return out;
 629 }
 630
 631 static int lkdtm_debugfs_open(struct inode *inode, struct file *file)
 632 {
 633         return 0;
 634 }
 635
 636
 637 static ssize_t int_hardware_entry(struct file *f, const char __user *buf,
 638                 size_t count, loff_t *off)
 639 {
 640         return do_register_entry(CN_INT_HARDWARE_ENTRY, f, buf, count, off);
 641 }
 642
 643 static ssize_t int_hw_irq_en(struct file *f, const char __user *buf,
 644                 size_t count, loff_t *off)
 645 {
 646         return do_register_entry(CN_INT_HW_IRQ_EN, f, buf, count, off);
 647 }
 648
 649 static ssize_t int_tasklet_entry(struct file *f, const char __user *buf,
 650                 size_t count, loff_t *off)
 651 {
 652         return do_register_entry(CN_INT_TASKLET_ENTRY, f, buf, count, off);
 653 }
 654
 655 static ssize_t fs_devrw_entry(struct file *f, const char __user *buf,
 656                 size_t count, loff_t *off)
 657 {
 658         return do_register_entry(CN_FS_DEVRW, f, buf, count, off);
 659 }
 660
 661 static ssize_t mem_swapout_entry(struct file *f, const char __user *buf,
 662                 size_t count, loff_t *off)
 663 {
 664         return do_register_entry(CN_MEM_SWAPOUT, f, buf, count, off);
 665 }
 666
 667 static ssize_t timeradd_entry(struct file *f, const char __user *buf,
 668                 size_t count, loff_t *off)
 669 {
 670         return do_register_entry(CN_TIMERADD, f, buf, count, off);
 671 }
 672
 673 static ssize_t scsi_dispatch_cmd_entry(struct file *f,
 674                 const char __user *buf, size_t count, loff_t *off)
 675 {
 676         return do_register_entry(CN_SCSI_DISPATCH_CMD, f, buf, count, off);
 677 }
 678
 679 static ssize_t ide_core_cp_entry(struct file *f, const char __user *buf,
 680                 size_t count, loff_t *off)
 681 {
 682         return do_register_entry(CN_IDE_CORE_CP, f, buf, count, off);
 683 }
 684
 685 /* Special entry to just crash directly. Available without KPROBEs */
 686 static ssize_t direct_entry(struct file *f, const char __user *user_buf,
 687                 size_t count, loff_t *off)
 688 {
 689         enum ctype type;
 690         char *buf;
 691
 692         if (count >= PAGE_SIZE)
 693                 return -EINVAL;
 694         if (count < 1)
 695                 return -EINVAL;
 696
 697         buf = (char *)__get_free_page(GFP_KERNEL);
 698         if (!buf)
 699                 return -ENOMEM;
 700         if (copy_from_user(buf, user_buf, count)) {
 701                 free_page((unsigned long) buf);
 702                 return -EFAULT;
 703         }
 704         /* NULL-terminate and remove enter */
 705         buf[count] = '\0';
 706         strim(buf);
 707
 708         type = parse_cp_type(buf, count);
 709         free_page((unsigned long) buf);
 710         if (type == CT_NONE)
 711                 return -EINVAL;
 712
 713         pr_info("Performing direct entry %s\n", cp_type_to_str(type));
 714         lkdtm_do_action(type);
 715         *off += count;
 716
 717         return count;
 718 }
 719
 720 struct crash_entry {
 721         const char *name;
 722         const struct file_operations fops;
 723 };
 724
 725 static const struct crash_entry crash_entries[] = {
 726         {"DIRECT", {.read = lkdtm_debugfs_read,
 727                         .llseek = generic_file_llseek,
 728                         .open = lkdtm_debugfs_open,
 729                         .write = direct_entry} },
 730         {"INT_HARDWARE_ENTRY", {.read = lkdtm_debugfs_read,
 731                         .llseek = generic_file_llseek,
 732                         .open = lkdtm_debugfs_open,
 733                         .write = int_hardware_entry} },
 734         {"INT_HW_IRQ_EN", {.read = lkdtm_debugfs_read,
 735                         .llseek = generic_file_llseek,
 736                         .open = lkdtm_debugfs_open,
 737                         .write = int_hw_irq_en} },
 738         {"INT_TASKLET_ENTRY", {.read = lkdtm_debugfs_read,
 739                         .llseek = generic_file_llseek,
 740                         .open = lkdtm_debugfs_open,
 741                         .write = int_tasklet_entry} },
 742         {"FS_DEVRW", {.read = lkdtm_debugfs_read,
 743                         .llseek = generic_file_llseek,
 744                         .open = lkdtm_debugfs_open,
 745                         .write = fs_devrw_entry} },
 746         {"MEM_SWAPOUT", {.read = lkdtm_debugfs_read,
 747                         .llseek = generic_file_llseek,
 748                         .open = lkdtm_debugfs_open,
 749                         .write = mem_swapout_entry} },
 750         {"TIMERADD", {.read = lkdtm_debugfs_read,
 751                         .llseek = generic_file_llseek,
 752                         .open = lkdtm_debugfs_open,
 753                         .write = timeradd_entry} },
 754         {"SCSI_DISPATCH_CMD", {.read = lkdtm_debugfs_read,
 755                         .llseek = generic_file_llseek,
 756                         .open = lkdtm_debugfs_open,
 757                         .write = scsi_dispatch_cmd_entry} },
 758         {"IDE_CORE_CP", {.read = lkdtm_debugfs_read,
 759                         .llseek = generic_file_llseek,
 760                         .open = lkdtm_debugfs_open,
 761                         .write = ide_core_cp_entry} },
 762 };
 763
 764 static struct dentry *lkdtm_debugfs_root;
 765
 766 static int __init lkdtm_module_init(void)
 767 {
 768         int ret = -EINVAL;
 769         int n_debugfs_entries = 1; /* Assume only the direct entry */
 770         int i;
 771
 772         /* Register debugfs interface */
 773         lkdtm_debugfs_root = debugfs_create_dir("provoke-crash", NULL);
 774         if (!lkdtm_debugfs_root) {
 775                 pr_err("creating root dir failed\n");
 776                 return -ENODEV;
 777         }
 778
 779 #ifdef CONFIG_KPROBES
 780         n_debugfs_entries = ARRAY_SIZE(crash_entries);
 781 #endif
 782
 783         for (i = 0; i < n_debugfs_entries; i++) {
 784                 const struct crash_entry *cur = &crash_entries[i];
 785                 struct dentry *de;
 786
 787                 de = debugfs_create_file(cur->name, 0644, lkdtm_debugfs_root,
 788                                 NULL, &cur->fops);
 789                 if (de == NULL) {
 790                         pr_err("could not create %s\n", cur->name);
 791                         goto out_err;
 792                 }
 793         }
 794
 795         if (lkdtm_parse_commandline() == -EINVAL) {
 796                 pr_info("Invalid command\n");
 797                 goto out_err;
 798         }
 799
 800         if (cpoint != CN_INVALID && cptype != CT_NONE) {
 801                 ret = lkdtm_register_cpoint(cpoint);
 802                 if (ret < 0) {
 803                         pr_info("Invalid crash point %d\n", cpoint);
 804                         goto out_err;
 805                 }
 806                 pr_info("Crash point %s of type %s registered\n",
 807                         cpoint_name, cpoint_type);
 808         } else {
 809                 pr_info("No crash points registered, enable through debugfs\n");
 810         }
 811
 812         return 0;
 813
 814 out_err:
 815         debugfs_remove_recursive(lkdtm_debugfs_root);
 816         return ret;
 817 }
 818
 819 static void __exit lkdtm_module_exit(void)
 820 {
 821         debugfs_remove_recursive(lkdtm_debugfs_root);
 822
 823         unregister_jprobe(&lkdtm);
 824         pr_info("Crash point unregistered\n");
 825 }
 826
 827 module_init(lkdtm_module_init);
 828 module_exit(lkdtm_module_exit);
 829
 830 MODULE_LICENSE("GPL");