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 #include <asm/cacheflush.h>
  50
  51 #ifdef CONFIG_IDE
  52 #include <linux/ide.h>
  53 #endif
  54
  55 /*
  56  * Make sure our attempts to over run the kernel stack doesn't trigger
  57  * a compiler warning when CONFIG_FRAME_WARN is set. Then make sure we
  58  * recurse past the end of THREAD_SIZE by default.
  59  */
  60 #if defined(CONFIG_FRAME_WARN) && (CONFIG_FRAME_WARN > 0)
  61 #define REC_STACK_SIZE (CONFIG_FRAME_WARN / 2)
  62 #else
  63 #define REC_STACK_SIZE (THREAD_SIZE / 8)
  64 #endif
  65 #define REC_NUM_DEFAULT ((THREAD_SIZE / REC_STACK_SIZE) * 2)
  66
  67 #define DEFAULT_COUNT 10
  68 #define EXEC_SIZE 64
  69
  70 enum cname {
  71         CN_INVALID,
  72         CN_INT_HARDWARE_ENTRY,
  73         CN_INT_HW_IRQ_EN,
  74         CN_INT_TASKLET_ENTRY,
  75         CN_FS_DEVRW,
  76         CN_MEM_SWAPOUT,
  77         CN_TIMERADD,
  78         CN_SCSI_DISPATCH_CMD,
  79         CN_IDE_CORE_CP,
  80         CN_DIRECT,
  81 };
  82
  83 enum ctype {
  84         CT_NONE,
  85         CT_PANIC,
  86         CT_BUG,
  87         CT_WARNING,
  88         CT_EXCEPTION,
  89         CT_LOOP,
  90         CT_OVERFLOW,
  91         CT_CORRUPT_STACK,
  92         CT_UNALIGNED_LOAD_STORE_WRITE,
  93         CT_OVERWRITE_ALLOCATION,
  94         CT_WRITE_AFTER_FREE,
  95         CT_READ_AFTER_FREE,
  96         CT_SOFTLOCKUP,
  97         CT_HARDLOCKUP,
  98         CT_SPINLOCKUP,
  99         CT_HUNG_TASK,
 100         CT_EXEC_DATA,
 101         CT_EXEC_STACK,
 102         CT_EXEC_KMALLOC,
 103         CT_EXEC_VMALLOC,
 104         CT_EXEC_USERSPACE,
 105         CT_ACCESS_USERSPACE,
 106         CT_WRITE_RO,
 107         CT_WRITE_KERN,
 108 };
 109
 110 static char* cp_name[] = {
 111         "INT_HARDWARE_ENTRY",
 112         "INT_HW_IRQ_EN",
 113         "INT_TASKLET_ENTRY",
 114         "FS_DEVRW",
 115         "MEM_SWAPOUT",
 116         "TIMERADD",
 117         "SCSI_DISPATCH_CMD",
 118         "IDE_CORE_CP",
 119         "DIRECT",
 120 };
 121
 122 static char* cp_type[] = {
 123         "PANIC",
 124         "BUG",
 125         "WARNING",
 126         "EXCEPTION",
 127         "LOOP",
 128         "OVERFLOW",
 129         "CORRUPT_STACK",
 130         "UNALIGNED_LOAD_STORE_WRITE",
 131         "OVERWRITE_ALLOCATION",
 132         "WRITE_AFTER_FREE",
 133         "READ_AFTER_FREE",
 134         "SOFTLOCKUP",
 135         "HARDLOCKUP",
 136         "SPINLOCKUP",
 137         "HUNG_TASK",
 138         "EXEC_DATA",
 139         "EXEC_STACK",
 140         "EXEC_KMALLOC",
 141         "EXEC_VMALLOC",
 142         "EXEC_USERSPACE",
 143         "ACCESS_USERSPACE",
 144         "WRITE_RO",
 145         "WRITE_KERN",
 146 };
 147
 148 static struct jprobe lkdtm;
 149
 150 static int lkdtm_parse_commandline(void);
 151 static void lkdtm_handler(void);
 152
 153 static char* cpoint_name;
 154 static char* cpoint_type;
 155 static int cpoint_count = DEFAULT_COUNT;
 156 static int recur_count = REC_NUM_DEFAULT;
 157
 158 static enum cname cpoint = CN_INVALID;
 159 static enum ctype cptype = CT_NONE;
 160 static int count = DEFAULT_COUNT;
 161 static DEFINE_SPINLOCK(count_lock);
 162 static DEFINE_SPINLOCK(lock_me_up);
 163
 164 static u8 data_area[EXEC_SIZE];
 165
 166 static const unsigned long rodata = 0xAA55AA55;
 167
 168 module_param(recur_count, int, 0644);
 169 MODULE_PARM_DESC(recur_count, " Recursion level for the stack overflow test");
 170 module_param(cpoint_name, charp, 0444);
 171 MODULE_PARM_DESC(cpoint_name, " Crash Point, where kernel is to be crashed");
 172 module_param(cpoint_type, charp, 0444);
 173 MODULE_PARM_DESC(cpoint_type, " Crash Point Type, action to be taken on "\
 174                                 "hitting the crash point");
 175 module_param(cpoint_count, int, 0644);
 176 MODULE_PARM_DESC(cpoint_count, " Crash Point Count, number of times the "\
 177                                 "crash point is to be hit to trigger action");
 178
 179 static unsigned int jp_do_irq(unsigned int irq)
 180 {
 181         lkdtm_handler();
 182         jprobe_return();
 183         return 0;
 184 }
 185
 186 static irqreturn_t jp_handle_irq_event(unsigned int irq,
 187                                        struct irqaction *action)
 188 {
 189         lkdtm_handler();
 190         jprobe_return();
 191         return 0;
 192 }
 193
 194 static void jp_tasklet_action(struct softirq_action *a)
 195 {
 196         lkdtm_handler();
 197         jprobe_return();
 198 }
 199
 200 static void jp_ll_rw_block(int rw, int nr, struct buffer_head *bhs[])
 201 {
 202         lkdtm_handler();
 203         jprobe_return();
 204 }
 205
 206 struct scan_control;
 207
 208 static unsigned long jp_shrink_inactive_list(unsigned long max_scan,
 209                                              struct zone *zone,
 210                                              struct scan_control *sc)
 211 {
 212         lkdtm_handler();
 213         jprobe_return();
 214         return 0;
 215 }
 216
 217 static int jp_hrtimer_start(struct hrtimer *timer, ktime_t tim,
 218                             const enum hrtimer_mode mode)
 219 {
 220         lkdtm_handler();
 221         jprobe_return();
 222         return 0;
 223 }
 224
 225 static int jp_scsi_dispatch_cmd(struct scsi_cmnd *cmd)
 226 {
 227         lkdtm_handler();
 228         jprobe_return();
 229         return 0;
 230 }
 231
 232 #ifdef CONFIG_IDE
 233 static int jp_generic_ide_ioctl(ide_drive_t *drive, struct file *file,
 234                         struct block_device *bdev, unsigned int cmd,
 235                         unsigned long arg)
 236 {
 237         lkdtm_handler();
 238         jprobe_return();
 239         return 0;
 240 }
 241 #endif
 242
 243 /* Return the crashpoint number or NONE if the name is invalid */
 244 static enum ctype parse_cp_type(const char *what, size_t count)
 245 {
 246         int i;
 247
 248         for (i = 0; i < ARRAY_SIZE(cp_type); i++) {
 249                 if (!strcmp(what, cp_type[i]))
 250                         return i + 1;
 251         }
 252
 253         return CT_NONE;
 254 }
 255
 256 static const char *cp_type_to_str(enum ctype type)
 257 {
 258         if (type == CT_NONE || type < 0 || type > ARRAY_SIZE(cp_type))
 259                 return "None";
 260
 261         return cp_type[type - 1];
 262 }
 263
 264 static const char *cp_name_to_str(enum cname name)
 265 {
 266         if (name == CN_INVALID || name < 0 || name > ARRAY_SIZE(cp_name))
 267                 return "INVALID";
 268
 269         return cp_name[name - 1];
 270 }
 271
 272
 273 static int lkdtm_parse_commandline(void)
 274 {
 275         int i;
 276         unsigned long flags;
 277
 278         if (cpoint_count < 1 || recur_count < 1)
 279                 return -EINVAL;
 280
 281         spin_lock_irqsave(&count_lock, flags);
 282         count = cpoint_count;
 283         spin_unlock_irqrestore(&count_lock, flags);
 284
 285         /* No special parameters */
 286         if (!cpoint_type && !cpoint_name)
 287                 return 0;
 288
 289         /* Neither or both of these need to be set */
 290         if (!cpoint_type || !cpoint_name)
 291                 return -EINVAL;
 292
 293         cptype = parse_cp_type(cpoint_type, strlen(cpoint_type));
 294         if (cptype == CT_NONE)
 295                 return -EINVAL;
 296
 297         for (i = 0; i < ARRAY_SIZE(cp_name); i++) {
 298                 if (!strcmp(cpoint_name, cp_name[i])) {
 299                         cpoint = i + 1;
 300                         return 0;
 301                 }
 302         }
 303
 304         /* Could not find a valid crash point */
 305         return -EINVAL;
 306 }
 307
 308 static int recursive_loop(int remaining)
 309 {
 310         char buf[REC_STACK_SIZE];
 311
 312         /* Make sure compiler does not optimize this away. */
 313         memset(buf, (remaining & 0xff) | 0x1, REC_STACK_SIZE);
 314         if (!remaining)
 315                 return 0;
 316         else
 317                 return recursive_loop(remaining - 1);
 318 }
 319
 320 static void do_nothing(void)
 321 {
 322         return;
 323 }
 324
 325 /* Must immediately follow do_nothing for size calculuations to work out. */
 326 static void do_overwritten(void)
 327 {
 328         pr_info("do_overwritten wasn't overwritten!\n");
 329         return;
 330 }
 331
 332 static noinline void corrupt_stack(void)
 333 {
 334         /* Use default char array length that triggers stack protection. */
 335         char data[8];
 336
 337         memset((void *)data, 0, 64);
 338 }
 339
 340 static void execute_location(void *dst)
 341 {
 342         void (*func)(void) = dst;
 343
 344         pr_info("attempting ok execution at %p\n", do_nothing);
 345         do_nothing();
 346
 347         memcpy(dst, do_nothing, EXEC_SIZE);
 348         flush_icache_range((unsigned long)dst, (unsigned long)dst + EXEC_SIZE);
 349         pr_info("attempting bad execution at %p\n", func);
 350         func();
 351 }
 352
 353 static void execute_user_location(void *dst)
 354 {
 355         /* Intentionally crossing kernel/user memory boundary. */
 356         void (*func)(void) = dst;
 357
 358         pr_info("attempting ok execution at %p\n", do_nothing);
 359         do_nothing();
 360
 361         if (copy_to_user((void __user *)dst, do_nothing, EXEC_SIZE))
 362                 return;
 363         flush_icache_range((unsigned long)dst, (unsigned long)dst + EXEC_SIZE);
 364         pr_info("attempting bad execution at %p\n", func);
 365         func();
 366 }
 367
 368 static void lkdtm_do_action(enum ctype which)
 369 {
 370         switch (which) {
 371         case CT_PANIC:
 372                 panic("dumptest");
 373                 break;
 374         case CT_BUG:
 375                 BUG();
 376                 break;
 377         case CT_WARNING:
 378                 WARN_ON(1);
 379                 break;
 380         case CT_EXCEPTION:
 381                 *((int *) 0) = 0;
 382                 break;
 383         case CT_LOOP:
 384                 for (;;)
 385                         ;
 386                 break;
 387         case CT_OVERFLOW:
 388                 (void) recursive_loop(recur_count);
 389                 break;
 390         case CT_CORRUPT_STACK:
 391                 corrupt_stack();
 392                 break;
 393         case CT_UNALIGNED_LOAD_STORE_WRITE: {
 394                 static u8 data[5] __attribute__((aligned(4))) = {1, 2,
 395                                 3, 4, 5};
 396                 u32 *p;
 397                 u32 val = 0x12345678;
 398
 399                 p = (u32 *)(data + 1);
 400                 if (*p == 0)
 401                         val = 0x87654321;
 402                 *p = val;
 403                  break;
 404         }
 405         case CT_OVERWRITE_ALLOCATION: {
 406                 size_t len = 1020;
 407                 u32 *data = kmalloc(len, GFP_KERNEL);
 408
 409                 data[1024 / sizeof(u32)] = 0x12345678;
 410                 kfree(data);
 411                 break;
 412         }
 413         case CT_WRITE_AFTER_FREE: {
 414                 size_t len = 1024;
 415                 u32 *data = kmalloc(len, GFP_KERNEL);
 416
 417                 kfree(data);
 418                 schedule();
 419                 memset(data, 0x78, len);
 420                 break;
 421         }
 422         case CT_READ_AFTER_FREE: {
 423                 int *base, *val, saw;
 424                 size_t len = 1024;
 425                 /*
 426                  * The slub allocator uses the first word to store the free
 427                  * pointer in some configurations. Use the middle of the
 428                  * allocation to avoid running into the freelist
 429                  */
 430                 size_t offset = (len / sizeof(*base)) / 2;
 431
 432                 base = kmalloc(len, GFP_KERNEL);
 433                 if (!base)
 434                         break;
 435
 436                 val = kmalloc(len, GFP_KERNEL);
 437                 if (!val)
 438                         break;
 439
 440                 *val = 0x12345678;
 441                 base[offset] = *val;
 442                 pr_info("Value in memory before free: %x\n", base[offset]);
 443
 444                 kfree(base);
 445
 446                 pr_info("Attempting bad read from freed memory\n");
 447                 saw = base[offset];
 448                 if (saw != *val) {
 449                         /* Good! Poisoning happened, so declare a win. */
 450                         pr_info("Memory correctly poisoned, calling BUG\n");
 451                         BUG();
 452                 }
 453                 pr_info("Memory was not poisoned\n");
 454
 455                 kfree(val);
 456                 break;
 457         }
 458         case CT_SOFTLOCKUP:
 459                 preempt_disable();
 460                 for (;;)
 461                         cpu_relax();
 462                 break;
 463         case CT_HARDLOCKUP:
 464                 local_irq_disable();
 465                 for (;;)
 466                         cpu_relax();
 467                 break;
 468         case CT_SPINLOCKUP:
 469                 /* Must be called twice to trigger. */
 470                 spin_lock(&lock_me_up);
 471                 /* Let sparse know we intended to exit holding the lock. */
 472                 __release(&lock_me_up);
 473                 break;
 474         case CT_HUNG_TASK:
 475                 set_current_state(TASK_UNINTERRUPTIBLE);
 476                 schedule();
 477                 break;
 478         case CT_EXEC_DATA:
 479                 execute_location(data_area);
 480                 break;
 481         case CT_EXEC_STACK: {
 482                 u8 stack_area[EXEC_SIZE];
 483                 execute_location(stack_area);
 484                 break;
 485         }
 486         case CT_EXEC_KMALLOC: {
 487                 u32 *kmalloc_area = kmalloc(EXEC_SIZE, GFP_KERNEL);
 488                 execute_location(kmalloc_area);
 489                 kfree(kmalloc_area);
 490                 break;
 491         }
 492         case CT_EXEC_VMALLOC: {
 493                 u32 *vmalloc_area = vmalloc(EXEC_SIZE);
 494                 execute_location(vmalloc_area);
 495                 vfree(vmalloc_area);
 496                 break;
 497         }
 498         case CT_EXEC_USERSPACE: {
 499                 unsigned long user_addr;
 500
 501                 user_addr = vm_mmap(NULL, 0, PAGE_SIZE,
 502                                     PROT_READ | PROT_WRITE | PROT_EXEC,
 503                                     MAP_ANONYMOUS | MAP_PRIVATE, 0);
 504                 if (user_addr >= TASK_SIZE) {
 505                         pr_warn("Failed to allocate user memory\n");
 506                         return;
 507                 }
 508                 execute_user_location((void *)user_addr);
 509                 vm_munmap(user_addr, PAGE_SIZE);
 510                 break;
 511         }
 512         case CT_ACCESS_USERSPACE: {
 513                 unsigned long user_addr, tmp = 0;
 514                 unsigned long *ptr;
 515
 516                 user_addr = vm_mmap(NULL, 0, PAGE_SIZE,
 517                                     PROT_READ | PROT_WRITE | PROT_EXEC,
 518                                     MAP_ANONYMOUS | MAP_PRIVATE, 0);
 519                 if (user_addr >= TASK_SIZE) {
 520                         pr_warn("Failed to allocate user memory\n");
 521                         return;
 522                 }
 523
 524                 if (copy_to_user((void __user *)user_addr, &tmp, sizeof(tmp))) {
 525                         pr_warn("copy_to_user failed\n");
 526                         vm_munmap(user_addr, PAGE_SIZE);
 527                         return;
 528                 }
 529
 530                 ptr = (unsigned long *)user_addr;
 531
 532                 pr_info("attempting bad read at %p\n", ptr);
 533                 tmp = *ptr;
 534                 tmp += 0xc0dec0de;
 535
 536                 pr_info("attempting bad write at %p\n", ptr);
 537                 *ptr = tmp;
 538
 539                 vm_munmap(user_addr, PAGE_SIZE);
 540
 541                 break;
 542         }
 543         case CT_WRITE_RO: {
 544                 unsigned long *ptr;
 545
 546                 ptr = (unsigned long *)&rodata;
 547
 548                 pr_info("attempting bad write at %p\n", ptr);
 549                 *ptr ^= 0xabcd1234;
 550
 551                 break;
 552         }
 553         case CT_WRITE_KERN: {
 554                 size_t size;
 555                 unsigned char *ptr;
 556
 557                 size = (unsigned long)do_overwritten -
 558                        (unsigned long)do_nothing;
 559                 ptr = (unsigned char *)do_overwritten;
 560
 561                 pr_info("attempting bad %zu byte write at %p\n", size, ptr);
 562                 memcpy(ptr, (unsigned char *)do_nothing, size);
 563                 flush_icache_range((unsigned long)ptr,
 564                                    (unsigned long)(ptr + size));
 565
 566                 do_overwritten();
 567                 break;
 568         }
 569         case CT_NONE:
 570         default:
 571                 break;
 572         }
 573
 574 }
 575
 576 static void lkdtm_handler(void)
 577 {
 578         unsigned long flags;
 579         bool do_it = false;
 580
 581         spin_lock_irqsave(&count_lock, flags);
 582         count--;
 583         pr_info("Crash point %s of type %s hit, trigger in %d rounds\n",
 584                 cp_name_to_str(cpoint), cp_type_to_str(cptype), count);
 585
 586         if (count == 0) {
 587                 do_it = true;
 588                 count = cpoint_count;
 589         }
 590         spin_unlock_irqrestore(&count_lock, flags);
 591
 592         if (do_it)
 593                 lkdtm_do_action(cptype);
 594 }
 595
 596 static int lkdtm_register_cpoint(enum cname which)
 597 {
 598         int ret;
 599
 600         cpoint = CN_INVALID;
 601         if (lkdtm.entry != NULL)
 602                 unregister_jprobe(&lkdtm);
 603
 604         switch (which) {
 605         case CN_DIRECT:
 606                 lkdtm_do_action(cptype);
 607                 return 0;
 608         case CN_INT_HARDWARE_ENTRY:
 609                 lkdtm.kp.symbol_name = "do_IRQ";
 610                 lkdtm.entry = (kprobe_opcode_t*) jp_do_irq;
 611                 break;
 612         case CN_INT_HW_IRQ_EN:
 613                 lkdtm.kp.symbol_name = "handle_IRQ_event";
 614                 lkdtm.entry = (kprobe_opcode_t*) jp_handle_irq_event;
 615                 break;
 616         case CN_INT_TASKLET_ENTRY:
 617                 lkdtm.kp.symbol_name = "tasklet_action";
 618                 lkdtm.entry = (kprobe_opcode_t*) jp_tasklet_action;
 619                 break;
 620         case CN_FS_DEVRW:
 621                 lkdtm.kp.symbol_name = "ll_rw_block";
 622                 lkdtm.entry = (kprobe_opcode_t*) jp_ll_rw_block;
 623                 break;
 624         case CN_MEM_SWAPOUT:
 625                 lkdtm.kp.symbol_name = "shrink_inactive_list";
 626                 lkdtm.entry = (kprobe_opcode_t*) jp_shrink_inactive_list;
 627                 break;
 628         case CN_TIMERADD:
 629                 lkdtm.kp.symbol_name = "hrtimer_start";
 630                 lkdtm.entry = (kprobe_opcode_t*) jp_hrtimer_start;
 631                 break;
 632         case CN_SCSI_DISPATCH_CMD:
 633                 lkdtm.kp.symbol_name = "scsi_dispatch_cmd";
 634                 lkdtm.entry = (kprobe_opcode_t*) jp_scsi_dispatch_cmd;
 635                 break;
 636         case CN_IDE_CORE_CP:
 637 #ifdef CONFIG_IDE
 638                 lkdtm.kp.symbol_name = "generic_ide_ioctl";
 639                 lkdtm.entry = (kprobe_opcode_t*) jp_generic_ide_ioctl;
 640 #else
 641                 pr_info("Crash point not available\n");
 642                 return -EINVAL;
 643 #endif
 644                 break;
 645         default:
 646                 pr_info("Invalid Crash Point\n");
 647                 return -EINVAL;
 648         }
 649
 650         cpoint = which;
 651         if ((ret = register_jprobe(&lkdtm)) < 0) {
 652                 pr_info("Couldn't register jprobe\n");
 653                 cpoint = CN_INVALID;
 654         }
 655
 656         return ret;
 657 }
 658
 659 static ssize_t do_register_entry(enum cname which, struct file *f,
 660                 const char __user *user_buf, size_t count, loff_t *off)
 661 {
 662         char *buf;
 663         int err;
 664
 665         if (count >= PAGE_SIZE)
 666                 return -EINVAL;
 667
 668         buf = (char *)__get_free_page(GFP_KERNEL);
 669         if (!buf)
 670                 return -ENOMEM;
 671         if (copy_from_user(buf, user_buf, count)) {
 672                 free_page((unsigned long) buf);
 673                 return -EFAULT;
 674         }
 675         /* NULL-terminate and remove enter */
 676         buf[count] = '\0';
 677         strim(buf);
 678
 679         cptype = parse_cp_type(buf, count);
 680         free_page((unsigned long) buf);
 681
 682         if (cptype == CT_NONE)
 683                 return -EINVAL;
 684
 685         err = lkdtm_register_cpoint(which);
 686         if (err < 0)
 687                 return err;
 688
 689         *off += count;
 690
 691         return count;
 692 }
 693
 694 /* Generic read callback that just prints out the available crash types */
 695 static ssize_t lkdtm_debugfs_read(struct file *f, char __user *user_buf,
 696                 size_t count, loff_t *off)
 697 {
 698         char *buf;
 699         int i, n, out;
 700
 701         buf = (char *)__get_free_page(GFP_KERNEL);
 702         if (buf == NULL)
 703                 return -ENOMEM;
 704
 705         n = snprintf(buf, PAGE_SIZE, "Available crash types:\n");
 706         for (i = 0; i < ARRAY_SIZE(cp_type); i++)
 707                 n += snprintf(buf + n, PAGE_SIZE - n, "%s\n", cp_type[i]);
 708         buf[n] = '\0';
 709
 710         out = simple_read_from_buffer(user_buf, count, off,
 711                                       buf, n);
 712         free_page((unsigned long) buf);
 713
 714         return out;
 715 }
 716
 717 static int lkdtm_debugfs_open(struct inode *inode, struct file *file)
 718 {
 719         return 0;
 720 }
 721
 722
 723 static ssize_t int_hardware_entry(struct file *f, const char __user *buf,
 724                 size_t count, loff_t *off)
 725 {
 726         return do_register_entry(CN_INT_HARDWARE_ENTRY, f, buf, count, off);
 727 }
 728
 729 static ssize_t int_hw_irq_en(struct file *f, const char __user *buf,
 730                 size_t count, loff_t *off)
 731 {
 732         return do_register_entry(CN_INT_HW_IRQ_EN, f, buf, count, off);
 733 }
 734
 735 static ssize_t int_tasklet_entry(struct file *f, const char __user *buf,
 736                 size_t count, loff_t *off)
 737 {
 738         return do_register_entry(CN_INT_TASKLET_ENTRY, f, buf, count, off);
 739 }
 740
 741 static ssize_t fs_devrw_entry(struct file *f, const char __user *buf,
 742                 size_t count, loff_t *off)
 743 {
 744         return do_register_entry(CN_FS_DEVRW, f, buf, count, off);
 745 }
 746
 747 static ssize_t mem_swapout_entry(struct file *f, const char __user *buf,
 748                 size_t count, loff_t *off)
 749 {
 750         return do_register_entry(CN_MEM_SWAPOUT, f, buf, count, off);
 751 }
 752
 753 static ssize_t timeradd_entry(struct file *f, const char __user *buf,
 754                 size_t count, loff_t *off)
 755 {
 756         return do_register_entry(CN_TIMERADD, f, buf, count, off);
 757 }
 758
 759 static ssize_t scsi_dispatch_cmd_entry(struct file *f,
 760                 const char __user *buf, size_t count, loff_t *off)
 761 {
 762         return do_register_entry(CN_SCSI_DISPATCH_CMD, f, buf, count, off);
 763 }
 764
 765 static ssize_t ide_core_cp_entry(struct file *f, const char __user *buf,
 766                 size_t count, loff_t *off)
 767 {
 768         return do_register_entry(CN_IDE_CORE_CP, f, buf, count, off);
 769 }
 770
 771 /* Special entry to just crash directly. Available without KPROBEs */
 772 static ssize_t direct_entry(struct file *f, const char __user *user_buf,
 773                 size_t count, loff_t *off)
 774 {
 775         enum ctype type;
 776         char *buf;
 777
 778         if (count >= PAGE_SIZE)
 779                 return -EINVAL;
 780         if (count < 1)
 781                 return -EINVAL;
 782
 783         buf = (char *)__get_free_page(GFP_KERNEL);
 784         if (!buf)
 785                 return -ENOMEM;
 786         if (copy_from_user(buf, user_buf, count)) {
 787                 free_page((unsigned long) buf);
 788                 return -EFAULT;
 789         }
 790         /* NULL-terminate and remove enter */
 791         buf[count] = '\0';
 792         strim(buf);
 793
 794         type = parse_cp_type(buf, count);
 795         free_page((unsigned long) buf);
 796         if (type == CT_NONE)
 797                 return -EINVAL;
 798
 799         pr_info("Performing direct entry %s\n", cp_type_to_str(type));
 800         lkdtm_do_action(type);
 801         *off += count;
 802
 803         return count;
 804 }
 805
 806 struct crash_entry {
 807         const char *name;
 808         const struct file_operations fops;
 809 };
 810
 811 static const struct crash_entry crash_entries[] = {
 812         {"DIRECT", {.read = lkdtm_debugfs_read,
 813                         .llseek = generic_file_llseek,
 814                         .open = lkdtm_debugfs_open,
 815                         .write = direct_entry} },
 816         {"INT_HARDWARE_ENTRY", {.read = lkdtm_debugfs_read,
 817                         .llseek = generic_file_llseek,
 818                         .open = lkdtm_debugfs_open,
 819                         .write = int_hardware_entry} },
 820         {"INT_HW_IRQ_EN", {.read = lkdtm_debugfs_read,
 821                         .llseek = generic_file_llseek,
 822                         .open = lkdtm_debugfs_open,
 823                         .write = int_hw_irq_en} },
 824         {"INT_TASKLET_ENTRY", {.read = lkdtm_debugfs_read,
 825                         .llseek = generic_file_llseek,
 826                         .open = lkdtm_debugfs_open,
 827                         .write = int_tasklet_entry} },
 828         {"FS_DEVRW", {.read = lkdtm_debugfs_read,
 829                         .llseek = generic_file_llseek,
 830                         .open = lkdtm_debugfs_open,
 831                         .write = fs_devrw_entry} },
 832         {"MEM_SWAPOUT", {.read = lkdtm_debugfs_read,
 833                         .llseek = generic_file_llseek,
 834                         .open = lkdtm_debugfs_open,
 835                         .write = mem_swapout_entry} },
 836         {"TIMERADD", {.read = lkdtm_debugfs_read,
 837                         .llseek = generic_file_llseek,
 838                         .open = lkdtm_debugfs_open,
 839                         .write = timeradd_entry} },
 840         {"SCSI_DISPATCH_CMD", {.read = lkdtm_debugfs_read,
 841                         .llseek = generic_file_llseek,
 842                         .open = lkdtm_debugfs_open,
 843                         .write = scsi_dispatch_cmd_entry} },
 844         {"IDE_CORE_CP", {.read = lkdtm_debugfs_read,
 845                         .llseek = generic_file_llseek,
 846                         .open = lkdtm_debugfs_open,
 847                         .write = ide_core_cp_entry} },
 848 };
 849
 850 static struct dentry *lkdtm_debugfs_root;
 851
 852 static int __init lkdtm_module_init(void)
 853 {
 854         int ret = -EINVAL;
 855         int n_debugfs_entries = 1; /* Assume only the direct entry */
 856         int i;
 857
 858         /* Register debugfs interface */
 859         lkdtm_debugfs_root = debugfs_create_dir("provoke-crash", NULL);
 860         if (!lkdtm_debugfs_root) {
 861                 pr_err("creating root dir failed\n");
 862                 return -ENODEV;
 863         }
 864
 865 #ifdef CONFIG_KPROBES
 866         n_debugfs_entries = ARRAY_SIZE(crash_entries);
 867 #endif
 868
 869         for (i = 0; i < n_debugfs_entries; i++) {
 870                 const struct crash_entry *cur = &crash_entries[i];
 871                 struct dentry *de;
 872
 873                 de = debugfs_create_file(cur->name, 0644, lkdtm_debugfs_root,
 874                                 NULL, &cur->fops);
 875                 if (de == NULL) {
 876                         pr_err("could not create %s\n", cur->name);
 877                         goto out_err;
 878                 }
 879         }
 880
 881         if (lkdtm_parse_commandline() == -EINVAL) {
 882                 pr_info("Invalid command\n");
 883                 goto out_err;
 884         }
 885
 886         if (cpoint != CN_INVALID && cptype != CT_NONE) {
 887                 ret = lkdtm_register_cpoint(cpoint);
 888                 if (ret < 0) {
 889                         pr_info("Invalid crash point %d\n", cpoint);
 890                         goto out_err;
 891                 }
 892                 pr_info("Crash point %s of type %s registered\n",
 893                         cpoint_name, cpoint_type);
 894         } else {
 895                 pr_info("No crash points registered, enable through debugfs\n");
 896         }
 897
 898         return 0;
 899
 900 out_err:
 901         debugfs_remove_recursive(lkdtm_debugfs_root);
 902         return ret;
 903 }
 904
 905 static void __exit lkdtm_module_exit(void)
 906 {
 907         debugfs_remove_recursive(lkdtm_debugfs_root);
 908
 909         unregister_jprobe(&lkdtm);
 910         pr_info("Crash point unregistered\n");
 911 }
 912
 913 module_init(lkdtm_module_init);
 914 module_exit(lkdtm_module_exit);
 915
 916 MODULE_LICENSE("GPL");
 917 MODULE_DESCRIPTION("Kprobe module for testing crash dumps");