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                 int *base;
 415                 size_t len = 1024;
 416                 /*
 417                  * The slub allocator uses the first word to store the free
 418                  * pointer in some configurations. Use the middle of the
 419                  * allocation to avoid running into the freelist
 420                  */
 421                 size_t offset = (len / sizeof(*base)) / 2;
 422
 423                 base = kmalloc(len, GFP_KERNEL);
 424                 pr_info("Allocated memory %p-%p\n", base, &base[offset * 2]);
 425                 kfree(base);
 426                 pr_info("Attempting bad write to freed memory at %p\n",
 427                         &base[offset]);
 428                 base[offset] = 0x0abcdef0;
 429                 break;
 430         }
 431         case CT_READ_AFTER_FREE: {
 432                 int *base, *val, saw;
 433                 size_t len = 1024;
 434                 /*
 435                  * The slub allocator uses the first word to store the free
 436                  * pointer in some configurations. Use the middle of the
 437                  * allocation to avoid running into the freelist
 438                  */
 439                 size_t offset = (len / sizeof(*base)) / 2;
 440
 441                 base = kmalloc(len, GFP_KERNEL);
 442                 if (!base)
 443                         break;
 444
 445                 val = kmalloc(len, GFP_KERNEL);
 446                 if (!val)
 447                         break;
 448
 449                 *val = 0x12345678;
 450                 base[offset] = *val;
 451                 pr_info("Value in memory before free: %x\n", base[offset]);
 452
 453                 kfree(base);
 454
 455                 pr_info("Attempting bad read from freed memory\n");
 456                 saw = base[offset];
 457                 if (saw != *val) {
 458                         /* Good! Poisoning happened, so declare a win. */
 459                         pr_info("Memory correctly poisoned, calling BUG\n");
 460                         BUG();
 461                 }
 462                 pr_info("Memory was not poisoned\n");
 463
 464                 kfree(val);
 465                 break;
 466         }
 467         case CT_SOFTLOCKUP:
 468                 preempt_disable();
 469                 for (;;)
 470                         cpu_relax();
 471                 break;
 472         case CT_HARDLOCKUP:
 473                 local_irq_disable();
 474                 for (;;)
 475                         cpu_relax();
 476                 break;
 477         case CT_SPINLOCKUP:
 478                 /* Must be called twice to trigger. */
 479                 spin_lock(&lock_me_up);
 480                 /* Let sparse know we intended to exit holding the lock. */
 481                 __release(&lock_me_up);
 482                 break;
 483         case CT_HUNG_TASK:
 484                 set_current_state(TASK_UNINTERRUPTIBLE);
 485                 schedule();
 486                 break;
 487         case CT_EXEC_DATA:
 488                 execute_location(data_area);
 489                 break;
 490         case CT_EXEC_STACK: {
 491                 u8 stack_area[EXEC_SIZE];
 492                 execute_location(stack_area);
 493                 break;
 494         }
 495         case CT_EXEC_KMALLOC: {
 496                 u32 *kmalloc_area = kmalloc(EXEC_SIZE, GFP_KERNEL);
 497                 execute_location(kmalloc_area);
 498                 kfree(kmalloc_area);
 499                 break;
 500         }
 501         case CT_EXEC_VMALLOC: {
 502                 u32 *vmalloc_area = vmalloc(EXEC_SIZE);
 503                 execute_location(vmalloc_area);
 504                 vfree(vmalloc_area);
 505                 break;
 506         }
 507         case CT_EXEC_USERSPACE: {
 508                 unsigned long user_addr;
 509
 510                 user_addr = vm_mmap(NULL, 0, PAGE_SIZE,
 511                                     PROT_READ | PROT_WRITE | PROT_EXEC,
 512                                     MAP_ANONYMOUS | MAP_PRIVATE, 0);
 513                 if (user_addr >= TASK_SIZE) {
 514                         pr_warn("Failed to allocate user memory\n");
 515                         return;
 516                 }
 517                 execute_user_location((void *)user_addr);
 518                 vm_munmap(user_addr, PAGE_SIZE);
 519                 break;
 520         }
 521         case CT_ACCESS_USERSPACE: {
 522                 unsigned long user_addr, tmp = 0;
 523                 unsigned long *ptr;
 524
 525                 user_addr = vm_mmap(NULL, 0, PAGE_SIZE,
 526                                     PROT_READ | PROT_WRITE | PROT_EXEC,
 527                                     MAP_ANONYMOUS | MAP_PRIVATE, 0);
 528                 if (user_addr >= TASK_SIZE) {
 529                         pr_warn("Failed to allocate user memory\n");
 530                         return;
 531                 }
 532
 533                 if (copy_to_user((void __user *)user_addr, &tmp, sizeof(tmp))) {
 534                         pr_warn("copy_to_user failed\n");
 535                         vm_munmap(user_addr, PAGE_SIZE);
 536                         return;
 537                 }
 538
 539                 ptr = (unsigned long *)user_addr;
 540
 541                 pr_info("attempting bad read at %p\n", ptr);
 542                 tmp = *ptr;
 543                 tmp += 0xc0dec0de;
 544
 545                 pr_info("attempting bad write at %p\n", ptr);
 546                 *ptr = tmp;
 547
 548                 vm_munmap(user_addr, PAGE_SIZE);
 549
 550                 break;
 551         }
 552         case CT_WRITE_RO: {
 553                 unsigned long *ptr;
 554
 555                 ptr = (unsigned long *)&rodata;
 556
 557                 pr_info("attempting bad write at %p\n", ptr);
 558                 *ptr ^= 0xabcd1234;
 559
 560                 break;
 561         }
 562         case CT_WRITE_KERN: {
 563                 size_t size;
 564                 unsigned char *ptr;
 565
 566                 size = (unsigned long)do_overwritten -
 567                        (unsigned long)do_nothing;
 568                 ptr = (unsigned char *)do_overwritten;
 569
 570                 pr_info("attempting bad %zu byte write at %p\n", size, ptr);
 571                 memcpy(ptr, (unsigned char *)do_nothing, size);
 572                 flush_icache_range((unsigned long)ptr,
 573                                    (unsigned long)(ptr + size));
 574
 575                 do_overwritten();
 576                 break;
 577         }
 578         case CT_NONE:
 579         default:
 580                 break;
 581         }
 582
 583 }
 584
 585 static void lkdtm_handler(void)
 586 {
 587         unsigned long flags;
 588         bool do_it = false;
 589
 590         spin_lock_irqsave(&count_lock, flags);
 591         count--;
 592         pr_info("Crash point %s of type %s hit, trigger in %d rounds\n",
 593                 cp_name_to_str(cpoint), cp_type_to_str(cptype), count);
 594
 595         if (count == 0) {
 596                 do_it = true;
 597                 count = cpoint_count;
 598         }
 599         spin_unlock_irqrestore(&count_lock, flags);
 600
 601         if (do_it)
 602                 lkdtm_do_action(cptype);
 603 }
 604
 605 static int lkdtm_register_cpoint(enum cname which)
 606 {
 607         int ret;
 608
 609         cpoint = CN_INVALID;
 610         if (lkdtm.entry != NULL)
 611                 unregister_jprobe(&lkdtm);
 612
 613         switch (which) {
 614         case CN_DIRECT:
 615                 lkdtm_do_action(cptype);
 616                 return 0;
 617         case CN_INT_HARDWARE_ENTRY:
 618                 lkdtm.kp.symbol_name = "do_IRQ";
 619                 lkdtm.entry = (kprobe_opcode_t*) jp_do_irq;
 620                 break;
 621         case CN_INT_HW_IRQ_EN:
 622                 lkdtm.kp.symbol_name = "handle_IRQ_event";
 623                 lkdtm.entry = (kprobe_opcode_t*) jp_handle_irq_event;
 624                 break;
 625         case CN_INT_TASKLET_ENTRY:
 626                 lkdtm.kp.symbol_name = "tasklet_action";
 627                 lkdtm.entry = (kprobe_opcode_t*) jp_tasklet_action;
 628                 break;
 629         case CN_FS_DEVRW:
 630                 lkdtm.kp.symbol_name = "ll_rw_block";
 631                 lkdtm.entry = (kprobe_opcode_t*) jp_ll_rw_block;
 632                 break;
 633         case CN_MEM_SWAPOUT:
 634                 lkdtm.kp.symbol_name = "shrink_inactive_list";
 635                 lkdtm.entry = (kprobe_opcode_t*) jp_shrink_inactive_list;
 636                 break;
 637         case CN_TIMERADD:
 638                 lkdtm.kp.symbol_name = "hrtimer_start";
 639                 lkdtm.entry = (kprobe_opcode_t*) jp_hrtimer_start;
 640                 break;
 641         case CN_SCSI_DISPATCH_CMD:
 642                 lkdtm.kp.symbol_name = "scsi_dispatch_cmd";
 643                 lkdtm.entry = (kprobe_opcode_t*) jp_scsi_dispatch_cmd;
 644                 break;
 645         case CN_IDE_CORE_CP:
 646 #ifdef CONFIG_IDE
 647                 lkdtm.kp.symbol_name = "generic_ide_ioctl";
 648                 lkdtm.entry = (kprobe_opcode_t*) jp_generic_ide_ioctl;
 649 #else
 650                 pr_info("Crash point not available\n");
 651                 return -EINVAL;
 652 #endif
 653                 break;
 654         default:
 655                 pr_info("Invalid Crash Point\n");
 656                 return -EINVAL;
 657         }
 658
 659         cpoint = which;
 660         if ((ret = register_jprobe(&lkdtm)) < 0) {
 661                 pr_info("Couldn't register jprobe\n");
 662                 cpoint = CN_INVALID;
 663         }
 664
 665         return ret;
 666 }
 667
 668 static ssize_t do_register_entry(enum cname which, struct file *f,
 669                 const char __user *user_buf, size_t count, loff_t *off)
 670 {
 671         char *buf;
 672         int err;
 673
 674         if (count >= PAGE_SIZE)
 675                 return -EINVAL;
 676
 677         buf = (char *)__get_free_page(GFP_KERNEL);
 678         if (!buf)
 679                 return -ENOMEM;
 680         if (copy_from_user(buf, user_buf, count)) {
 681                 free_page((unsigned long) buf);
 682                 return -EFAULT;
 683         }
 684         /* NULL-terminate and remove enter */
 685         buf[count] = '\0';
 686         strim(buf);
 687
 688         cptype = parse_cp_type(buf, count);
 689         free_page((unsigned long) buf);
 690
 691         if (cptype == CT_NONE)
 692                 return -EINVAL;
 693
 694         err = lkdtm_register_cpoint(which);
 695         if (err < 0)
 696                 return err;
 697
 698         *off += count;
 699
 700         return count;
 701 }
 702
 703 /* Generic read callback that just prints out the available crash types */
 704 static ssize_t lkdtm_debugfs_read(struct file *f, char __user *user_buf,
 705                 size_t count, loff_t *off)
 706 {
 707         char *buf;
 708         int i, n, out;
 709
 710         buf = (char *)__get_free_page(GFP_KERNEL);
 711         if (buf == NULL)
 712                 return -ENOMEM;
 713
 714         n = snprintf(buf, PAGE_SIZE, "Available crash types:\n");
 715         for (i = 0; i < ARRAY_SIZE(cp_type); i++)
 716                 n += snprintf(buf + n, PAGE_SIZE - n, "%s\n", cp_type[i]);
 717         buf[n] = '\0';
 718
 719         out = simple_read_from_buffer(user_buf, count, off,
 720                                       buf, n);
 721         free_page((unsigned long) buf);
 722
 723         return out;
 724 }
 725
 726 static int lkdtm_debugfs_open(struct inode *inode, struct file *file)
 727 {
 728         return 0;
 729 }
 730
 731
 732 static ssize_t int_hardware_entry(struct file *f, const char __user *buf,
 733                 size_t count, loff_t *off)
 734 {
 735         return do_register_entry(CN_INT_HARDWARE_ENTRY, f, buf, count, off);
 736 }
 737
 738 static ssize_t int_hw_irq_en(struct file *f, const char __user *buf,
 739                 size_t count, loff_t *off)
 740 {
 741         return do_register_entry(CN_INT_HW_IRQ_EN, f, buf, count, off);
 742 }
 743
 744 static ssize_t int_tasklet_entry(struct file *f, const char __user *buf,
 745                 size_t count, loff_t *off)
 746 {
 747         return do_register_entry(CN_INT_TASKLET_ENTRY, f, buf, count, off);
 748 }
 749
 750 static ssize_t fs_devrw_entry(struct file *f, const char __user *buf,
 751                 size_t count, loff_t *off)
 752 {
 753         return do_register_entry(CN_FS_DEVRW, f, buf, count, off);
 754 }
 755
 756 static ssize_t mem_swapout_entry(struct file *f, const char __user *buf,
 757                 size_t count, loff_t *off)
 758 {
 759         return do_register_entry(CN_MEM_SWAPOUT, f, buf, count, off);
 760 }
 761
 762 static ssize_t timeradd_entry(struct file *f, const char __user *buf,
 763                 size_t count, loff_t *off)
 764 {
 765         return do_register_entry(CN_TIMERADD, f, buf, count, off);
 766 }
 767
 768 static ssize_t scsi_dispatch_cmd_entry(struct file *f,
 769                 const char __user *buf, size_t count, loff_t *off)
 770 {
 771         return do_register_entry(CN_SCSI_DISPATCH_CMD, f, buf, count, off);
 772 }
 773
 774 static ssize_t ide_core_cp_entry(struct file *f, const char __user *buf,
 775                 size_t count, loff_t *off)
 776 {
 777         return do_register_entry(CN_IDE_CORE_CP, f, buf, count, off);
 778 }
 779
 780 /* Special entry to just crash directly. Available without KPROBEs */
 781 static ssize_t direct_entry(struct file *f, const char __user *user_buf,
 782                 size_t count, loff_t *off)
 783 {
 784         enum ctype type;
 785         char *buf;
 786
 787         if (count >= PAGE_SIZE)
 788                 return -EINVAL;
 789         if (count < 1)
 790                 return -EINVAL;
 791
 792         buf = (char *)__get_free_page(GFP_KERNEL);
 793         if (!buf)
 794                 return -ENOMEM;
 795         if (copy_from_user(buf, user_buf, count)) {
 796                 free_page((unsigned long) buf);
 797                 return -EFAULT;
 798         }
 799         /* NULL-terminate and remove enter */
 800         buf[count] = '\0';
 801         strim(buf);
 802
 803         type = parse_cp_type(buf, count);
 804         free_page((unsigned long) buf);
 805         if (type == CT_NONE)
 806                 return -EINVAL;
 807
 808         pr_info("Performing direct entry %s\n", cp_type_to_str(type));
 809         lkdtm_do_action(type);
 810         *off += count;
 811
 812         return count;
 813 }
 814
 815 struct crash_entry {
 816         const char *name;
 817         const struct file_operations fops;
 818 };
 819
 820 static const struct crash_entry crash_entries[] = {
 821         {"DIRECT", {.read = lkdtm_debugfs_read,
 822                         .llseek = generic_file_llseek,
 823                         .open = lkdtm_debugfs_open,
 824                         .write = direct_entry} },
 825         {"INT_HARDWARE_ENTRY", {.read = lkdtm_debugfs_read,
 826                         .llseek = generic_file_llseek,
 827                         .open = lkdtm_debugfs_open,
 828                         .write = int_hardware_entry} },
 829         {"INT_HW_IRQ_EN", {.read = lkdtm_debugfs_read,
 830                         .llseek = generic_file_llseek,
 831                         .open = lkdtm_debugfs_open,
 832                         .write = int_hw_irq_en} },
 833         {"INT_TASKLET_ENTRY", {.read = lkdtm_debugfs_read,
 834                         .llseek = generic_file_llseek,
 835                         .open = lkdtm_debugfs_open,
 836                         .write = int_tasklet_entry} },
 837         {"FS_DEVRW", {.read = lkdtm_debugfs_read,
 838                         .llseek = generic_file_llseek,
 839                         .open = lkdtm_debugfs_open,
 840                         .write = fs_devrw_entry} },
 841         {"MEM_SWAPOUT", {.read = lkdtm_debugfs_read,
 842                         .llseek = generic_file_llseek,
 843                         .open = lkdtm_debugfs_open,
 844                         .write = mem_swapout_entry} },
 845         {"TIMERADD", {.read = lkdtm_debugfs_read,
 846                         .llseek = generic_file_llseek,
 847                         .open = lkdtm_debugfs_open,
 848                         .write = timeradd_entry} },
 849         {"SCSI_DISPATCH_CMD", {.read = lkdtm_debugfs_read,
 850                         .llseek = generic_file_llseek,
 851                         .open = lkdtm_debugfs_open,
 852                         .write = scsi_dispatch_cmd_entry} },
 853         {"IDE_CORE_CP", {.read = lkdtm_debugfs_read,
 854                         .llseek = generic_file_llseek,
 855                         .open = lkdtm_debugfs_open,
 856                         .write = ide_core_cp_entry} },
 857 };
 858
 859 static struct dentry *lkdtm_debugfs_root;
 860
 861 static int __init lkdtm_module_init(void)
 862 {
 863         int ret = -EINVAL;
 864         int n_debugfs_entries = 1; /* Assume only the direct entry */
 865         int i;
 866
 867         /* Register debugfs interface */
 868         lkdtm_debugfs_root = debugfs_create_dir("provoke-crash", NULL);
 869         if (!lkdtm_debugfs_root) {
 870                 pr_err("creating root dir failed\n");
 871                 return -ENODEV;
 872         }
 873
 874 #ifdef CONFIG_KPROBES
 875         n_debugfs_entries = ARRAY_SIZE(crash_entries);
 876 #endif
 877
 878         for (i = 0; i < n_debugfs_entries; i++) {
 879                 const struct crash_entry *cur = &crash_entries[i];
 880                 struct dentry *de;
 881
 882                 de = debugfs_create_file(cur->name, 0644, lkdtm_debugfs_root,
 883                                 NULL, &cur->fops);
 884                 if (de == NULL) {
 885                         pr_err("could not create %s\n", cur->name);
 886                         goto out_err;
 887                 }
 888         }
 889
 890         if (lkdtm_parse_commandline() == -EINVAL) {
 891                 pr_info("Invalid command\n");
 892                 goto out_err;
 893         }
 894
 895         if (cpoint != CN_INVALID && cptype != CT_NONE) {
 896                 ret = lkdtm_register_cpoint(cpoint);
 897                 if (ret < 0) {
 898                         pr_info("Invalid crash point %d\n", cpoint);
 899                         goto out_err;
 900                 }
 901                 pr_info("Crash point %s of type %s registered\n",
 902                         cpoint_name, cpoint_type);
 903         } else {
 904                 pr_info("No crash points registered, enable through debugfs\n");
 905         }
 906
 907         return 0;
 908
 909 out_err:
 910         debugfs_remove_recursive(lkdtm_debugfs_root);
 911         return ret;
 912 }
 913
 914 static void __exit lkdtm_module_exit(void)
 915 {
 916         debugfs_remove_recursive(lkdtm_debugfs_root);
 917
 918         unregister_jprobe(&lkdtm);
 919         pr_info("Crash point unregistered\n");
 920 }
 921
 922 module_init(lkdtm_module_init);
 923 module_exit(lkdtm_module_exit);
 924
 925 MODULE_LICENSE("GPL");
 926 MODULE_DESCRIPTION("Kprobe module for testing crash dumps");