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_SOFTLOCKUP,
  96         CT_HARDLOCKUP,
  97         CT_SPINLOCKUP,
  98         CT_HUNG_TASK,
  99         CT_EXEC_DATA,
 100         CT_EXEC_STACK,
 101         CT_EXEC_KMALLOC,
 102         CT_EXEC_VMALLOC,
 103         CT_EXEC_USERSPACE,
 104         CT_ACCESS_USERSPACE,
 105         CT_WRITE_RO,
 106         CT_WRITE_RO_AFTER_INIT,
 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         "SOFTLOCKUP",
 134         "HARDLOCKUP",
 135         "SPINLOCKUP",
 136         "HUNG_TASK",
 137         "EXEC_DATA",
 138         "EXEC_STACK",
 139         "EXEC_KMALLOC",
 140         "EXEC_VMALLOC",
 141         "EXEC_USERSPACE",
 142         "ACCESS_USERSPACE",
 143         "WRITE_RO",
 144         "WRITE_RO_AFTER_INIT",
 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 static unsigned long ro_after_init __ro_after_init = 0x55AA5500;
 168
 169 module_param(recur_count, int, 0644);
 170 MODULE_PARM_DESC(recur_count, " Recursion level for the stack overflow test");
 171 module_param(cpoint_name, charp, 0444);
 172 MODULE_PARM_DESC(cpoint_name, " Crash Point, where kernel is to be crashed");
 173 module_param(cpoint_type, charp, 0444);
 174 MODULE_PARM_DESC(cpoint_type, " Crash Point Type, action to be taken on "\
 175                                 "hitting the crash point");
 176 module_param(cpoint_count, int, 0644);
 177 MODULE_PARM_DESC(cpoint_count, " Crash Point Count, number of times the "\
 178                                 "crash point is to be hit to trigger action");
 179
 180 static unsigned int jp_do_irq(unsigned int irq)
 181 {
 182         lkdtm_handler();
 183         jprobe_return();
 184         return 0;
 185 }
 186
 187 static irqreturn_t jp_handle_irq_event(unsigned int irq,
 188                                        struct irqaction *action)
 189 {
 190         lkdtm_handler();
 191         jprobe_return();
 192         return 0;
 193 }
 194
 195 static void jp_tasklet_action(struct softirq_action *a)
 196 {
 197         lkdtm_handler();
 198         jprobe_return();
 199 }
 200
 201 static void jp_ll_rw_block(int rw, int nr, struct buffer_head *bhs[])
 202 {
 203         lkdtm_handler();
 204         jprobe_return();
 205 }
 206
 207 struct scan_control;
 208
 209 static unsigned long jp_shrink_inactive_list(unsigned long max_scan,
 210                                              struct zone *zone,
 211                                              struct scan_control *sc)
 212 {
 213         lkdtm_handler();
 214         jprobe_return();
 215         return 0;
 216 }
 217
 218 static int jp_hrtimer_start(struct hrtimer *timer, ktime_t tim,
 219                             const enum hrtimer_mode mode)
 220 {
 221         lkdtm_handler();
 222         jprobe_return();
 223         return 0;
 224 }
 225
 226 static int jp_scsi_dispatch_cmd(struct scsi_cmnd *cmd)
 227 {
 228         lkdtm_handler();
 229         jprobe_return();
 230         return 0;
 231 }
 232
 233 #ifdef CONFIG_IDE
 234 static int jp_generic_ide_ioctl(ide_drive_t *drive, struct file *file,
 235                         struct block_device *bdev, unsigned int cmd,
 236                         unsigned long arg)
 237 {
 238         lkdtm_handler();
 239         jprobe_return();
 240         return 0;
 241 }
 242 #endif
 243
 244 /* Return the crashpoint number or NONE if the name is invalid */
 245 static enum ctype parse_cp_type(const char *what, size_t count)
 246 {
 247         int i;
 248
 249         for (i = 0; i < ARRAY_SIZE(cp_type); i++) {
 250                 if (!strcmp(what, cp_type[i]))
 251                         return i + 1;
 252         }
 253
 254         return CT_NONE;
 255 }
 256
 257 static const char *cp_type_to_str(enum ctype type)
 258 {
 259         if (type == CT_NONE || type < 0 || type > ARRAY_SIZE(cp_type))
 260                 return "None";
 261
 262         return cp_type[type - 1];
 263 }
 264
 265 static const char *cp_name_to_str(enum cname name)
 266 {
 267         if (name == CN_INVALID || name < 0 || name > ARRAY_SIZE(cp_name))
 268                 return "INVALID";
 269
 270         return cp_name[name - 1];
 271 }
 272
 273
 274 static int lkdtm_parse_commandline(void)
 275 {
 276         int i;
 277         unsigned long flags;
 278
 279         if (cpoint_count < 1 || recur_count < 1)
 280                 return -EINVAL;
 281
 282         spin_lock_irqsave(&count_lock, flags);
 283         count = cpoint_count;
 284         spin_unlock_irqrestore(&count_lock, flags);
 285
 286         /* No special parameters */
 287         if (!cpoint_type && !cpoint_name)
 288                 return 0;
 289
 290         /* Neither or both of these need to be set */
 291         if (!cpoint_type || !cpoint_name)
 292                 return -EINVAL;
 293
 294         cptype = parse_cp_type(cpoint_type, strlen(cpoint_type));
 295         if (cptype == CT_NONE)
 296                 return -EINVAL;
 297
 298         for (i = 0; i < ARRAY_SIZE(cp_name); i++) {
 299                 if (!strcmp(cpoint_name, cp_name[i])) {
 300                         cpoint = i + 1;
 301                         return 0;
 302                 }
 303         }
 304
 305         /* Could not find a valid crash point */
 306         return -EINVAL;
 307 }
 308
 309 static int recursive_loop(int remaining)
 310 {
 311         char buf[REC_STACK_SIZE];
 312
 313         /* Make sure compiler does not optimize this away. */
 314         memset(buf, (remaining & 0xff) | 0x1, REC_STACK_SIZE);
 315         if (!remaining)
 316                 return 0;
 317         else
 318                 return recursive_loop(remaining - 1);
 319 }
 320
 321 static void do_nothing(void)
 322 {
 323         return;
 324 }
 325
 326 /* Must immediately follow do_nothing for size calculuations to work out. */
 327 static void do_overwritten(void)
 328 {
 329         pr_info("do_overwritten wasn't overwritten!\n");
 330         return;
 331 }
 332
 333 static noinline void corrupt_stack(void)
 334 {
 335         /* Use default char array length that triggers stack protection. */
 336         char data[8];
 337
 338         memset((void *)data, 0, 64);
 339 }
 340
 341 static void execute_location(void *dst)
 342 {
 343         void (*func)(void) = dst;
 344
 345         pr_info("attempting ok execution at %p\n", do_nothing);
 346         do_nothing();
 347
 348         memcpy(dst, do_nothing, EXEC_SIZE);
 349         flush_icache_range((unsigned long)dst, (unsigned long)dst + EXEC_SIZE);
 350         pr_info("attempting bad execution at %p\n", func);
 351         func();
 352 }
 353
 354 static void execute_user_location(void *dst)
 355 {
 356         /* Intentionally crossing kernel/user memory boundary. */
 357         void (*func)(void) = dst;
 358
 359         pr_info("attempting ok execution at %p\n", do_nothing);
 360         do_nothing();
 361
 362         if (copy_to_user((void __user *)dst, do_nothing, EXEC_SIZE))
 363                 return;
 364         flush_icache_range((unsigned long)dst, (unsigned long)dst + EXEC_SIZE);
 365         pr_info("attempting bad execution at %p\n", func);
 366         func();
 367 }
 368
 369 static void lkdtm_do_action(enum ctype which)
 370 {
 371         switch (which) {
 372         case CT_PANIC:
 373                 panic("dumptest");
 374                 break;
 375         case CT_BUG:
 376                 BUG();
 377                 break;
 378         case CT_WARNING:
 379                 WARN_ON(1);
 380                 break;
 381         case CT_EXCEPTION:
 382                 *((int *) 0) = 0;
 383                 break;
 384         case CT_LOOP:
 385                 for (;;)
 386                         ;
 387                 break;
 388         case CT_OVERFLOW:
 389                 (void) recursive_loop(recur_count);
 390                 break;
 391         case CT_CORRUPT_STACK:
 392                 corrupt_stack();
 393                 break;
 394         case CT_UNALIGNED_LOAD_STORE_WRITE: {
 395                 static u8 data[5] __attribute__((aligned(4))) = {1, 2,
 396                                 3, 4, 5};
 397                 u32 *p;
 398                 u32 val = 0x12345678;
 399
 400                 p = (u32 *)(data + 1);
 401                 if (*p == 0)
 402                         val = 0x87654321;
 403                 *p = val;
 404                  break;
 405         }
 406         case CT_OVERWRITE_ALLOCATION: {
 407                 size_t len = 1020;
 408                 u32 *data = kmalloc(len, GFP_KERNEL);
 409
 410                 data[1024 / sizeof(u32)] = 0x12345678;
 411                 kfree(data);
 412                 break;
 413         }
 414         case CT_WRITE_AFTER_FREE: {
 415                 size_t len = 1024;
 416                 u32 *data = kmalloc(len, GFP_KERNEL);
 417
 418                 kfree(data);
 419                 schedule();
 420                 memset(data, 0x78, len);
 421                 break;
 422         }
 423         case CT_SOFTLOCKUP:
 424                 preempt_disable();
 425                 for (;;)
 426                         cpu_relax();
 427                 break;
 428         case CT_HARDLOCKUP:
 429                 local_irq_disable();
 430                 for (;;)
 431                         cpu_relax();
 432                 break;
 433         case CT_SPINLOCKUP:
 434                 /* Must be called twice to trigger. */
 435                 spin_lock(&lock_me_up);
 436                 /* Let sparse know we intended to exit holding the lock. */
 437                 __release(&lock_me_up);
 438                 break;
 439         case CT_HUNG_TASK:
 440                 set_current_state(TASK_UNINTERRUPTIBLE);
 441                 schedule();
 442                 break;
 443         case CT_EXEC_DATA:
 444                 execute_location(data_area);
 445                 break;
 446         case CT_EXEC_STACK: {
 447                 u8 stack_area[EXEC_SIZE];
 448                 execute_location(stack_area);
 449                 break;
 450         }
 451         case CT_EXEC_KMALLOC: {
 452                 u32 *kmalloc_area = kmalloc(EXEC_SIZE, GFP_KERNEL);
 453                 execute_location(kmalloc_area);
 454                 kfree(kmalloc_area);
 455                 break;
 456         }
 457         case CT_EXEC_VMALLOC: {
 458                 u32 *vmalloc_area = vmalloc(EXEC_SIZE);
 459                 execute_location(vmalloc_area);
 460                 vfree(vmalloc_area);
 461                 break;
 462         }
 463         case CT_EXEC_USERSPACE: {
 464                 unsigned long user_addr;
 465
 466                 user_addr = vm_mmap(NULL, 0, PAGE_SIZE,
 467                                     PROT_READ | PROT_WRITE | PROT_EXEC,
 468                                     MAP_ANONYMOUS | MAP_PRIVATE, 0);
 469                 if (user_addr >= TASK_SIZE) {
 470                         pr_warn("Failed to allocate user memory\n");
 471                         return;
 472                 }
 473                 execute_user_location((void *)user_addr);
 474                 vm_munmap(user_addr, PAGE_SIZE);
 475                 break;
 476         }
 477         case CT_ACCESS_USERSPACE: {
 478                 unsigned long user_addr, tmp = 0;
 479                 unsigned long *ptr;
 480
 481                 user_addr = vm_mmap(NULL, 0, PAGE_SIZE,
 482                                     PROT_READ | PROT_WRITE | PROT_EXEC,
 483                                     MAP_ANONYMOUS | MAP_PRIVATE, 0);
 484                 if (user_addr >= TASK_SIZE) {
 485                         pr_warn("Failed to allocate user memory\n");
 486                         return;
 487                 }
 488
 489                 if (copy_to_user((void __user *)user_addr, &tmp, sizeof(tmp))) {
 490                         pr_warn("copy_to_user failed\n");
 491                         vm_munmap(user_addr, PAGE_SIZE);
 492                         return;
 493                 }
 494
 495                 ptr = (unsigned long *)user_addr;
 496
 497                 pr_info("attempting bad read at %p\n", ptr);
 498                 tmp = *ptr;
 499                 tmp += 0xc0dec0de;
 500
 501                 pr_info("attempting bad write at %p\n", ptr);
 502                 *ptr = tmp;
 503
 504                 vm_munmap(user_addr, PAGE_SIZE);
 505
 506                 break;
 507         }
 508         case CT_WRITE_RO: {
 509                 /* Explicitly cast away "const" for the test. */
 510                 unsigned long *ptr = (unsigned long *)&rodata;
 511
 512                 pr_info("attempting bad rodata write at %p\n", ptr);
 513                 *ptr ^= 0xabcd1234;
 514
 515                 break;
 516         }
 517         case CT_WRITE_RO_AFTER_INIT: {
 518                 unsigned long *ptr = &ro_after_init;
 519
 520                 /*
 521                  * Verify we were written to during init. Since an Oops
 522                  * is considered a "success", a failure is to just skip the
 523                  * real test.
 524                  */
 525                 if ((*ptr & 0xAA) != 0xAA) {
 526                         pr_info("%p was NOT written during init!?\n", ptr);
 527                         break;
 528                 }
 529
 530                 pr_info("attempting bad ro_after_init write at %p\n", ptr);
 531                 *ptr ^= 0xabcd1234;
 532
 533                 break;
 534         }
 535         case CT_WRITE_KERN: {
 536                 size_t size;
 537                 unsigned char *ptr;
 538
 539                 size = (unsigned long)do_overwritten -
 540                        (unsigned long)do_nothing;
 541                 ptr = (unsigned char *)do_overwritten;
 542
 543                 pr_info("attempting bad %zu byte write at %p\n", size, ptr);
 544                 memcpy(ptr, (unsigned char *)do_nothing, size);
 545                 flush_icache_range((unsigned long)ptr,
 546                                    (unsigned long)(ptr + size));
 547
 548                 do_overwritten();
 549                 break;
 550         }
 551         case CT_NONE:
 552         default:
 553                 break;
 554         }
 555
 556 }
 557
 558 static void lkdtm_handler(void)
 559 {
 560         unsigned long flags;
 561         bool do_it = false;
 562
 563         spin_lock_irqsave(&count_lock, flags);
 564         count--;
 565         pr_info("Crash point %s of type %s hit, trigger in %d rounds\n",
 566                 cp_name_to_str(cpoint), cp_type_to_str(cptype), count);
 567
 568         if (count == 0) {
 569                 do_it = true;
 570                 count = cpoint_count;
 571         }
 572         spin_unlock_irqrestore(&count_lock, flags);
 573
 574         if (do_it)
 575                 lkdtm_do_action(cptype);
 576 }
 577
 578 static int lkdtm_register_cpoint(enum cname which)
 579 {
 580         int ret;
 581
 582         cpoint = CN_INVALID;
 583         if (lkdtm.entry != NULL)
 584                 unregister_jprobe(&lkdtm);
 585
 586         switch (which) {
 587         case CN_DIRECT:
 588                 lkdtm_do_action(cptype);
 589                 return 0;
 590         case CN_INT_HARDWARE_ENTRY:
 591                 lkdtm.kp.symbol_name = "do_IRQ";
 592                 lkdtm.entry = (kprobe_opcode_t*) jp_do_irq;
 593                 break;
 594         case CN_INT_HW_IRQ_EN:
 595                 lkdtm.kp.symbol_name = "handle_IRQ_event";
 596                 lkdtm.entry = (kprobe_opcode_t*) jp_handle_irq_event;
 597                 break;
 598         case CN_INT_TASKLET_ENTRY:
 599                 lkdtm.kp.symbol_name = "tasklet_action";
 600                 lkdtm.entry = (kprobe_opcode_t*) jp_tasklet_action;
 601                 break;
 602         case CN_FS_DEVRW:
 603                 lkdtm.kp.symbol_name = "ll_rw_block";
 604                 lkdtm.entry = (kprobe_opcode_t*) jp_ll_rw_block;
 605                 break;
 606         case CN_MEM_SWAPOUT:
 607                 lkdtm.kp.symbol_name = "shrink_inactive_list";
 608                 lkdtm.entry = (kprobe_opcode_t*) jp_shrink_inactive_list;
 609                 break;
 610         case CN_TIMERADD:
 611                 lkdtm.kp.symbol_name = "hrtimer_start";
 612                 lkdtm.entry = (kprobe_opcode_t*) jp_hrtimer_start;
 613                 break;
 614         case CN_SCSI_DISPATCH_CMD:
 615                 lkdtm.kp.symbol_name = "scsi_dispatch_cmd";
 616                 lkdtm.entry = (kprobe_opcode_t*) jp_scsi_dispatch_cmd;
 617                 break;
 618         case CN_IDE_CORE_CP:
 619 #ifdef CONFIG_IDE
 620                 lkdtm.kp.symbol_name = "generic_ide_ioctl";
 621                 lkdtm.entry = (kprobe_opcode_t*) jp_generic_ide_ioctl;
 622 #else
 623                 pr_info("Crash point not available\n");
 624                 return -EINVAL;
 625 #endif
 626                 break;
 627         default:
 628                 pr_info("Invalid Crash Point\n");
 629                 return -EINVAL;
 630         }
 631
 632         cpoint = which;
 633         if ((ret = register_jprobe(&lkdtm)) < 0) {
 634                 pr_info("Couldn't register jprobe\n");
 635                 cpoint = CN_INVALID;
 636         }
 637
 638         return ret;
 639 }
 640
 641 static ssize_t do_register_entry(enum cname which, struct file *f,
 642                 const char __user *user_buf, size_t count, loff_t *off)
 643 {
 644         char *buf;
 645         int err;
 646
 647         if (count >= PAGE_SIZE)
 648                 return -EINVAL;
 649
 650         buf = (char *)__get_free_page(GFP_KERNEL);
 651         if (!buf)
 652                 return -ENOMEM;
 653         if (copy_from_user(buf, user_buf, count)) {
 654                 free_page((unsigned long) buf);
 655                 return -EFAULT;
 656         }
 657         /* NULL-terminate and remove enter */
 658         buf[count] = '\0';
 659         strim(buf);
 660
 661         cptype = parse_cp_type(buf, count);
 662         free_page((unsigned long) buf);
 663
 664         if (cptype == CT_NONE)
 665                 return -EINVAL;
 666
 667         err = lkdtm_register_cpoint(which);
 668         if (err < 0)
 669                 return err;
 670
 671         *off += count;
 672
 673         return count;
 674 }
 675
 676 /* Generic read callback that just prints out the available crash types */
 677 static ssize_t lkdtm_debugfs_read(struct file *f, char __user *user_buf,
 678                 size_t count, loff_t *off)
 679 {
 680         char *buf;
 681         int i, n, out;
 682
 683         buf = (char *)__get_free_page(GFP_KERNEL);
 684         if (buf == NULL)
 685                 return -ENOMEM;
 686
 687         n = snprintf(buf, PAGE_SIZE, "Available crash types:\n");
 688         for (i = 0; i < ARRAY_SIZE(cp_type); i++)
 689                 n += snprintf(buf + n, PAGE_SIZE - n, "%s\n", cp_type[i]);
 690         buf[n] = '\0';
 691
 692         out = simple_read_from_buffer(user_buf, count, off,
 693                                       buf, n);
 694         free_page((unsigned long) buf);
 695
 696         return out;
 697 }
 698
 699 static int lkdtm_debugfs_open(struct inode *inode, struct file *file)
 700 {
 701         return 0;
 702 }
 703
 704
 705 static ssize_t int_hardware_entry(struct file *f, const char __user *buf,
 706                 size_t count, loff_t *off)
 707 {
 708         return do_register_entry(CN_INT_HARDWARE_ENTRY, f, buf, count, off);
 709 }
 710
 711 static ssize_t int_hw_irq_en(struct file *f, const char __user *buf,
 712                 size_t count, loff_t *off)
 713 {
 714         return do_register_entry(CN_INT_HW_IRQ_EN, f, buf, count, off);
 715 }
 716
 717 static ssize_t int_tasklet_entry(struct file *f, const char __user *buf,
 718                 size_t count, loff_t *off)
 719 {
 720         return do_register_entry(CN_INT_TASKLET_ENTRY, f, buf, count, off);
 721 }
 722
 723 static ssize_t fs_devrw_entry(struct file *f, const char __user *buf,
 724                 size_t count, loff_t *off)
 725 {
 726         return do_register_entry(CN_FS_DEVRW, f, buf, count, off);
 727 }
 728
 729 static ssize_t mem_swapout_entry(struct file *f, const char __user *buf,
 730                 size_t count, loff_t *off)
 731 {
 732         return do_register_entry(CN_MEM_SWAPOUT, f, buf, count, off);
 733 }
 734
 735 static ssize_t timeradd_entry(struct file *f, const char __user *buf,
 736                 size_t count, loff_t *off)
 737 {
 738         return do_register_entry(CN_TIMERADD, f, buf, count, off);
 739 }
 740
 741 static ssize_t scsi_dispatch_cmd_entry(struct file *f,
 742                 const char __user *buf, size_t count, loff_t *off)
 743 {
 744         return do_register_entry(CN_SCSI_DISPATCH_CMD, f, buf, count, off);
 745 }
 746
 747 static ssize_t ide_core_cp_entry(struct file *f, const char __user *buf,
 748                 size_t count, loff_t *off)
 749 {
 750         return do_register_entry(CN_IDE_CORE_CP, f, buf, count, off);
 751 }
 752
 753 /* Special entry to just crash directly. Available without KPROBEs */
 754 static ssize_t direct_entry(struct file *f, const char __user *user_buf,
 755                 size_t count, loff_t *off)
 756 {
 757         enum ctype type;
 758         char *buf;
 759
 760         if (count >= PAGE_SIZE)
 761                 return -EINVAL;
 762         if (count < 1)
 763                 return -EINVAL;
 764
 765         buf = (char *)__get_free_page(GFP_KERNEL);
 766         if (!buf)
 767                 return -ENOMEM;
 768         if (copy_from_user(buf, user_buf, count)) {
 769                 free_page((unsigned long) buf);
 770                 return -EFAULT;
 771         }
 772         /* NULL-terminate and remove enter */
 773         buf[count] = '\0';
 774         strim(buf);
 775
 776         type = parse_cp_type(buf, count);
 777         free_page((unsigned long) buf);
 778         if (type == CT_NONE)
 779                 return -EINVAL;
 780
 781         pr_info("Performing direct entry %s\n", cp_type_to_str(type));
 782         lkdtm_do_action(type);
 783         *off += count;
 784
 785         return count;
 786 }
 787
 788 struct crash_entry {
 789         const char *name;
 790         const struct file_operations fops;
 791 };
 792
 793 static const struct crash_entry crash_entries[] = {
 794         {"DIRECT", {.read = lkdtm_debugfs_read,
 795                         .llseek = generic_file_llseek,
 796                         .open = lkdtm_debugfs_open,
 797                         .write = direct_entry} },
 798         {"INT_HARDWARE_ENTRY", {.read = lkdtm_debugfs_read,
 799                         .llseek = generic_file_llseek,
 800                         .open = lkdtm_debugfs_open,
 801                         .write = int_hardware_entry} },
 802         {"INT_HW_IRQ_EN", {.read = lkdtm_debugfs_read,
 803                         .llseek = generic_file_llseek,
 804                         .open = lkdtm_debugfs_open,
 805                         .write = int_hw_irq_en} },
 806         {"INT_TASKLET_ENTRY", {.read = lkdtm_debugfs_read,
 807                         .llseek = generic_file_llseek,
 808                         .open = lkdtm_debugfs_open,
 809                         .write = int_tasklet_entry} },
 810         {"FS_DEVRW", {.read = lkdtm_debugfs_read,
 811                         .llseek = generic_file_llseek,
 812                         .open = lkdtm_debugfs_open,
 813                         .write = fs_devrw_entry} },
 814         {"MEM_SWAPOUT", {.read = lkdtm_debugfs_read,
 815                         .llseek = generic_file_llseek,
 816                         .open = lkdtm_debugfs_open,
 817                         .write = mem_swapout_entry} },
 818         {"TIMERADD", {.read = lkdtm_debugfs_read,
 819                         .llseek = generic_file_llseek,
 820                         .open = lkdtm_debugfs_open,
 821                         .write = timeradd_entry} },
 822         {"SCSI_DISPATCH_CMD", {.read = lkdtm_debugfs_read,
 823                         .llseek = generic_file_llseek,
 824                         .open = lkdtm_debugfs_open,
 825                         .write = scsi_dispatch_cmd_entry} },
 826         {"IDE_CORE_CP", {.read = lkdtm_debugfs_read,
 827                         .llseek = generic_file_llseek,
 828                         .open = lkdtm_debugfs_open,
 829                         .write = ide_core_cp_entry} },
 830 };
 831
 832 static struct dentry *lkdtm_debugfs_root;
 833
 834 static int __init lkdtm_module_init(void)
 835 {
 836         int ret = -EINVAL;
 837         int n_debugfs_entries = 1; /* Assume only the direct entry */
 838         int i;
 839
 840         /* Make sure we can write to __ro_after_init values during __init */
 841         ro_after_init |= 0xAA;
 842
 843         /* Register debugfs interface */
 844         lkdtm_debugfs_root = debugfs_create_dir("provoke-crash", NULL);
 845         if (!lkdtm_debugfs_root) {
 846                 pr_err("creating root dir failed\n");
 847                 return -ENODEV;
 848         }
 849
 850 #ifdef CONFIG_KPROBES
 851         n_debugfs_entries = ARRAY_SIZE(crash_entries);
 852 #endif
 853
 854         for (i = 0; i < n_debugfs_entries; i++) {
 855                 const struct crash_entry *cur = &crash_entries[i];
 856                 struct dentry *de;
 857
 858                 de = debugfs_create_file(cur->name, 0644, lkdtm_debugfs_root,
 859                                 NULL, &cur->fops);
 860                 if (de == NULL) {
 861                         pr_err("could not create %s\n", cur->name);
 862                         goto out_err;
 863                 }
 864         }
 865
 866         if (lkdtm_parse_commandline() == -EINVAL) {
 867                 pr_info("Invalid command\n");
 868                 goto out_err;
 869         }
 870
 871         if (cpoint != CN_INVALID && cptype != CT_NONE) {
 872                 ret = lkdtm_register_cpoint(cpoint);
 873                 if (ret < 0) {
 874                         pr_info("Invalid crash point %d\n", cpoint);
 875                         goto out_err;
 876                 }
 877                 pr_info("Crash point %s of type %s registered\n",
 878                         cpoint_name, cpoint_type);
 879         } else {
 880                 pr_info("No crash points registered, enable through debugfs\n");
 881         }
 882
 883         return 0;
 884
 885 out_err:
 886         debugfs_remove_recursive(lkdtm_debugfs_root);
 887         return ret;
 888 }
 889
 890 static void __exit lkdtm_module_exit(void)
 891 {
 892         debugfs_remove_recursive(lkdtm_debugfs_root);
 893
 894         unregister_jprobe(&lkdtm);
 895         pr_info("Crash point unregistered\n");
 896 }
 897
 898 module_init(lkdtm_module_init);
 899 module_exit(lkdtm_module_exit);
 900
 901 MODULE_LICENSE("GPL");
 902 MODULE_DESCRIPTION("Kprobe module for testing crash dumps");