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   1 /*
   2  *  Copyright (C) 1991, 1992  Linus Torvalds
   3  *  Copyright (C) 2000, 2001, 2002 Andi Kleen, SuSE Labs
   4  */
   5 #include <linux/kallsyms.h>
   6 #include <linux/kprobes.h>
   7 #include <linux/uaccess.h>
   8 #include <linux/utsname.h>
   9 #include <linux/hardirq.h>
  10 #include <linux/kdebug.h>
  11 #include <linux/module.h>
  12 #include <linux/ptrace.h>
  13 #include <linux/kexec.h>
  14 #include <linux/bug.h>
  15 #include <linux/nmi.h>
  16
  17 #include <asm/stacktrace.h>
  18
  19 int panic_on_unrecovered_nmi;
  20 int kstack_depth_to_print = 12;
  21 static unsigned int code_bytes = 64;
  22 static int die_counter;
  23
  24 void printk_address(unsigned long address, int reliable)
  25 {
  26         printk(" [<%p>] %s%pS\n", (void *) address,
  27                         reliable ? "" : "? ", (void *) address);
  28 }
  29
  30 static unsigned long *in_exception_stack(unsigned cpu, unsigned long stack,
  31                                         unsigned *usedp, char **idp)
  32 {
  33         static char ids[][8] = {
  34                 [DEBUG_STACK - 1] = "#DB",
  35                 [NMI_STACK - 1] = "NMI",
  36                 [DOUBLEFAULT_STACK - 1] = "#DF",
  37                 [STACKFAULT_STACK - 1] = "#SS",
  38                 [MCE_STACK - 1] = "#MC",
  39 #if DEBUG_STKSZ > EXCEPTION_STKSZ
  40                 [N_EXCEPTION_STACKS ...
  41                         N_EXCEPTION_STACKS + DEBUG_STKSZ / EXCEPTION_STKSZ - 2] = "#DB[?]"
  42 #endif
  43         };
  44         unsigned k;
  45
  46         /*
  47          * Iterate over all exception stacks, and figure out whether
  48          * 'stack' is in one of them:
  49          */
  50         for (k = 0; k < N_EXCEPTION_STACKS; k++) {
  51                 unsigned long end = per_cpu(orig_ist, cpu).ist[k];
  52                 /*
  53                  * Is 'stack' above this exception frame's end?
  54                  * If yes then skip to the next frame.
  55                  */
  56                 if (stack >= end)
  57                         continue;
  58                 /*
  59                  * Is 'stack' above this exception frame's start address?
  60                  * If yes then we found the right frame.
  61                  */
  62                 if (stack >= end - EXCEPTION_STKSZ) {
  63                         /*
  64                          * Make sure we only iterate through an exception
  65                          * stack once. If it comes up for the second time
  66                          * then there's something wrong going on - just
  67                          * break out and return NULL:
  68                          */
  69                         if (*usedp & (1U << k))
  70                                 break;
  71                         *usedp |= 1U << k;
  72                         *idp = ids[k];
  73                         return (unsigned long *)end;
  74                 }
  75                 /*
  76                  * If this is a debug stack, and if it has a larger size than
  77                  * the usual exception stacks, then 'stack' might still
  78                  * be within the lower portion of the debug stack:
  79                  */
  80 #if DEBUG_STKSZ > EXCEPTION_STKSZ
  81                 if (k == DEBUG_STACK - 1 && stack >= end - DEBUG_STKSZ) {
  82                         unsigned j = N_EXCEPTION_STACKS - 1;
  83
  84                         /*
  85                          * Black magic. A large debug stack is composed of
  86                          * multiple exception stack entries, which we
  87                          * iterate through now. Dont look:
  88                          */
  89                         do {
  90                                 ++j;
  91                                 end -= EXCEPTION_STKSZ;
  92                                 ids[j][4] = '1' + (j - N_EXCEPTION_STACKS);
  93                         } while (stack < end - EXCEPTION_STKSZ);
  94                         if (*usedp & (1U << j))
  95                                 break;
  96                         *usedp |= 1U << j;
  97                         *idp = ids[j];
  98                         return (unsigned long *)end;
  99                 }
 100 #endif
 101         }
 102         return NULL;
 103 }
 104
 105 /*
 106  * x86-64 can have up to three kernel stacks:
 107  * process stack
 108  * interrupt stack
 109  * severe exception (double fault, nmi, stack fault, debug, mce) hardware stack
 110  */
 111
 112 static inline int valid_stack_ptr(struct thread_info *tinfo,
 113                         void *p, unsigned int size, void *end)
 114 {
 115         void *t = tinfo;
 116         if (end) {
 117                 if (p < end && p >= (end-THREAD_SIZE))
 118                         return 1;
 119                 else
 120                         return 0;
 121         }
 122         return p > t && p < t + THREAD_SIZE - size;
 123 }
 124
 125 /* The form of the top of the frame on the stack */
 126 struct stack_frame {
 127         struct stack_frame *next_frame;
 128         unsigned long return_address;
 129 };
 130
 131 static inline unsigned long
 132 print_context_stack(struct thread_info *tinfo,
 133                 unsigned long *stack, unsigned long bp,
 134                 const struct stacktrace_ops *ops, void *data,
 135                 unsigned long *end)
 136 {
 137         struct stack_frame *frame = (struct stack_frame *)bp;
 138
 139         while (valid_stack_ptr(tinfo, stack, sizeof(*stack), end)) {
 140                 unsigned long addr;
 141
 142                 addr = *stack;
 143                 if (__kernel_text_address(addr)) {
 144                         if ((unsigned long) stack == bp + 8) {
 145                                 ops->address(data, addr, 1);
 146                                 frame = frame->next_frame;
 147                                 bp = (unsigned long) frame;
 148                         } else {
 149                                 ops->address(data, addr, bp == 0);
 150                         }
 151                 }
 152                 stack++;
 153         }
 154         return bp;
 155 }
 156
 157 void dump_trace(struct task_struct *task, struct pt_regs *regs,
 158                 unsigned long *stack, unsigned long bp,
 159                 const struct stacktrace_ops *ops, void *data)
 160 {
 161         const unsigned cpu = get_cpu();
 162         unsigned long *irqstack_end = (unsigned long *)cpu_pda(cpu)->irqstackptr;
 163         unsigned used = 0;
 164         struct thread_info *tinfo;
 165
 166         if (!task)
 167                 task = current;
 168
 169         if (!stack) {
 170                 unsigned long dummy;
 171                 stack = &dummy;
 172                 if (task && task != current)
 173                         stack = (unsigned long *)task->thread.sp;
 174         }
 175
 176 #ifdef CONFIG_FRAME_POINTER
 177         if (!bp) {
 178                 if (task == current) {
 179                         /* Grab bp right from our regs */
 180                         asm("movq %%rbp, %0" : "=r" (bp) : );
 181                 } else {
 182                         /* bp is the last reg pushed by switch_to */
 183                         bp = *(unsigned long *) task->thread.sp;
 184                 }
 185         }
 186 #endif
 187
 188         /*
 189          * Print function call entries in all stacks, starting at the
 190          * current stack address. If the stacks consist of nested
 191          * exceptions
 192          */
 193         tinfo = task_thread_info(task);
 194         for (;;) {
 195                 char *id;
 196                 unsigned long *estack_end;
 197                 estack_end = in_exception_stack(cpu, (unsigned long)stack,
 198                                                 &used, &id);
 199
 200                 if (estack_end) {
 201                         if (ops->stack(data, id) < 0)
 202                                 break;
 203
 204                         bp = print_context_stack(tinfo, stack, bp, ops,
 205                                                         data, estack_end);
 206                         ops->stack(data, "<EOE>");
 207                         /*
 208                          * We link to the next stack via the
 209                          * second-to-last pointer (index -2 to end) in the
 210                          * exception stack:
 211                          */
 212                         stack = (unsigned long *) estack_end[-2];
 213                         continue;
 214                 }
 215                 if (irqstack_end) {
 216                         unsigned long *irqstack;
 217                         irqstack = irqstack_end -
 218                                 (IRQSTACKSIZE - 64) / sizeof(*irqstack);
 219
 220                         if (stack >= irqstack && stack < irqstack_end) {
 221                                 if (ops->stack(data, "IRQ") < 0)
 222                                         break;
 223                                 bp = print_context_stack(tinfo, stack, bp,
 224                                                 ops, data, irqstack_end);
 225                                 /*
 226                                  * We link to the next stack (which would be
 227                                  * the process stack normally) the last
 228                                  * pointer (index -1 to end) in the IRQ stack:
 229                                  */
 230                                 stack = (unsigned long *) (irqstack_end[-1]);
 231                                 irqstack_end = NULL;
 232                                 ops->stack(data, "EOI");
 233                                 continue;
 234                         }
 235                 }
 236                 break;
 237         }
 238
 239         /*
 240          * This handles the process stack:
 241          */
 242         bp = print_context_stack(tinfo, stack, bp, ops, data, NULL);
 243         put_cpu();
 244 }
 245 EXPORT_SYMBOL(dump_trace);
 246
 247 static void
 248 print_trace_warning_symbol(void *data, char *msg, unsigned long symbol)
 249 {
 250         print_symbol(msg, symbol);
 251         printk("\n");
 252 }
 253
 254 static void print_trace_warning(void *data, char *msg)
 255 {
 256         printk("%s\n", msg);
 257 }
 258
 259 static int print_trace_stack(void *data, char *name)
 260 {
 261         printk(" <%s> ", name);
 262         return 0;
 263 }
 264
 265 static void print_trace_address(void *data, unsigned long addr, int reliable)
 266 {
 267         touch_nmi_watchdog();
 268         printk_address(addr, reliable);
 269 }
 270
 271 static const struct stacktrace_ops print_trace_ops = {
 272         .warning = print_trace_warning,
 273         .warning_symbol = print_trace_warning_symbol,
 274         .stack = print_trace_stack,
 275         .address = print_trace_address,
 276 };
 277
 278 static void
 279 show_trace_log_lvl(struct task_struct *task, struct pt_regs *regs,
 280                 unsigned long *stack, unsigned long bp, char *log_lvl)
 281 {
 282         printk("Call Trace:\n");
 283         dump_trace(task, regs, stack, bp, &print_trace_ops, log_lvl);
 284 }
 285
 286 void show_trace(struct task_struct *task, struct pt_regs *regs,
 287                 unsigned long *stack, unsigned long bp)
 288 {
 289         show_trace_log_lvl(task, regs, stack, bp, "");
 290 }
 291
 292 static void
 293 show_stack_log_lvl(struct task_struct *task, struct pt_regs *regs,
 294                 unsigned long *sp, unsigned long bp, char *log_lvl)
 295 {
 296         unsigned long *stack;
 297         int i;
 298         const int cpu = smp_processor_id();
 299         unsigned long *irqstack_end =
 300                 (unsigned long *) (cpu_pda(cpu)->irqstackptr);
 301         unsigned long *irqstack =
 302                 (unsigned long *) (cpu_pda(cpu)->irqstackptr - IRQSTACKSIZE);
 303
 304         /*
 305          * debugging aid: "show_stack(NULL, NULL);" prints the
 306          * back trace for this cpu.
 307          */
 308
 309         if (sp == NULL) {
 310                 if (task)
 311                         sp = (unsigned long *)task->thread.sp;
 312                 else
 313                         sp = (unsigned long *)&sp;
 314         }
 315
 316         stack = sp;
 317         for (i = 0; i < kstack_depth_to_print; i++) {
 318                 if (stack >= irqstack && stack <= irqstack_end) {
 319                         if (stack == irqstack_end) {
 320                                 stack = (unsigned long *) (irqstack_end[-1]);
 321                                 printk(" <EOI> ");
 322                         }
 323                 } else {
 324                 if (((long) stack & (THREAD_SIZE-1)) == 0)
 325                         break;
 326                 }
 327                 if (i && ((i % 4) == 0))
 328                         printk("\n");
 329                 printk(" %016lx", *stack++);
 330                 touch_nmi_watchdog();
 331         }
 332         printk("\n");
 333         show_trace_log_lvl(task, regs, sp, bp, log_lvl);
 334 }
 335
 336 void show_stack(struct task_struct *task, unsigned long *sp)
 337 {
 338         show_stack_log_lvl(task, NULL, sp, 0, "");
 339 }
 340
 341 /*
 342  * The architecture-independent dump_stack generator
 343  */
 344 void dump_stack(void)
 345 {
 346         unsigned long bp = 0;
 347         unsigned long stack;
 348
 349 #ifdef CONFIG_FRAME_POINTER
 350         if (!bp)
 351                 asm("movq %%rbp, %0" : "=r" (bp) : );
 352 #endif
 353
 354         printk("Pid: %d, comm: %.20s %s %s %.*s\n",
 355                 current->pid, current->comm, print_tainted(),
 356                 init_utsname()->release,
 357                 (int)strcspn(init_utsname()->version, " "),
 358                 init_utsname()->version);
 359         show_trace(NULL, NULL, &stack, bp);
 360 }
 361 EXPORT_SYMBOL(dump_stack);
 362
 363 void show_registers(struct pt_regs *regs)
 364 {
 365         int i;
 366         unsigned long sp;
 367         const int cpu = smp_processor_id();
 368         struct task_struct *cur = cpu_pda(cpu)->pcurrent;
 369
 370         sp = regs->sp;
 371         printk("CPU %d ", cpu);
 372         __show_regs(regs, 1);
 373         printk("Process %s (pid: %d, threadinfo %p, task %p)\n",
 374                 cur->comm, cur->pid, task_thread_info(cur), cur);
 375
 376         /*
 377          * When in-kernel, we also print out the stack and code at the
 378          * time of the fault..
 379          */
 380         if (!user_mode(regs)) {
 381                 unsigned int code_prologue = code_bytes * 43 / 64;
 382                 unsigned int code_len = code_bytes;
 383                 unsigned char c;
 384                 u8 *ip;
 385
 386                 printk("Stack: ");
 387                 show_stack_log_lvl(NULL, regs, (unsigned long *)sp,
 388                                 regs->bp, "");
 389
 390                 printk(KERN_EMERG "Code: ");
 391
 392                 ip = (u8 *)regs->ip - code_prologue;
 393                 if (ip < (u8 *)PAGE_OFFSET || probe_kernel_address(ip, c)) {
 394                         /* try starting at RIP */
 395                         ip = (u8 *)regs->ip;
 396                         code_len = code_len - code_prologue + 1;
 397                 }
 398                 for (i = 0; i < code_len; i++, ip++) {
 399                         if (ip < (u8 *)PAGE_OFFSET ||
 400                                         probe_kernel_address(ip, c)) {
 401                                 printk(" Bad RIP value.");
 402                                 break;
 403                         }
 404                         if (ip == (u8 *)regs->ip)
 405                                 printk("<%02x> ", c);
 406                         else
 407                                 printk("%02x ", c);
 408                 }
 409         }
 410         printk("\n");
 411 }
 412
 413 int is_valid_bugaddr(unsigned long ip)
 414 {
 415         unsigned short ud2;
 416
 417         if (__copy_from_user(&ud2, (const void __user *) ip, sizeof(ud2)))
 418                 return 0;
 419
 420         return ud2 == 0x0b0f;
 421 }
 422
 423 static raw_spinlock_t die_lock = __RAW_SPIN_LOCK_UNLOCKED;
 424 static int die_owner = -1;
 425 static unsigned int die_nest_count;
 426
 427 unsigned __kprobes long oops_begin(void)
 428 {
 429         int cpu;
 430         unsigned long flags;
 431
 432         oops_enter();
 433
 434         /* racy, but better than risking deadlock. */
 435         raw_local_irq_save(flags);
 436         cpu = smp_processor_id();
 437         if (!__raw_spin_trylock(&die_lock)) {
 438                 if (cpu == die_owner)
 439                         /* nested oops. should stop eventually */;
 440                 else
 441                         __raw_spin_lock(&die_lock);
 442         }
 443         die_nest_count++;
 444         die_owner = cpu;
 445         console_verbose();
 446         bust_spinlocks(1);
 447         return flags;
 448 }
 449
 450 void __kprobes oops_end(unsigned long flags, struct pt_regs *regs, int signr)
 451 {
 452         die_owner = -1;
 453         bust_spinlocks(0);
 454         die_nest_count--;
 455         if (!die_nest_count)
 456                 /* Nest count reaches zero, release the lock. */
 457                 __raw_spin_unlock(&die_lock);
 458         raw_local_irq_restore(flags);
 459         if (!regs) {
 460                 oops_exit();
 461                 return;
 462         }
 463         if (in_interrupt())
 464                 panic("Fatal exception in interrupt");
 465         if (panic_on_oops)
 466                 panic("Fatal exception");
 467         oops_exit();
 468         do_exit(signr);
 469 }
 470
 471 int __kprobes __die(const char *str, struct pt_regs *regs, long err)
 472 {
 473         printk(KERN_EMERG "%s: %04lx [%u] ", str, err & 0xffff, ++die_counter);
 474 #ifdef CONFIG_PREEMPT
 475         printk("PREEMPT ");
 476 #endif
 477 #ifdef CONFIG_SMP
 478         printk("SMP ");
 479 #endif
 480 #ifdef CONFIG_DEBUG_PAGEALLOC
 481         printk("DEBUG_PAGEALLOC");
 482 #endif
 483         printk("\n");
 484         if (notify_die(DIE_OOPS, str, regs, err,
 485                         current->thread.trap_no, SIGSEGV) == NOTIFY_STOP)
 486                 return 1;
 487
 488         show_registers(regs);
 489         add_taint(TAINT_DIE);
 490         /* Executive summary in case the oops scrolled away */
 491         printk(KERN_ALERT "RIP ");
 492         printk_address(regs->ip, 1);
 493         printk(" RSP <%016lx>\n", regs->sp);
 494         if (kexec_should_crash(current))
 495                 crash_kexec(regs);
 496         return 0;
 497 }
 498
 499 void die(const char *str, struct pt_regs *regs, long err)
 500 {
 501         unsigned long flags = oops_begin();
 502
 503         if (!user_mode(regs))
 504                 report_bug(regs->ip, regs);
 505
 506         if (__die(str, regs, err))
 507                 regs = NULL;
 508         oops_end(flags, regs, SIGSEGV);
 509 }
 510
 511 notrace __kprobes void
 512 die_nmi(char *str, struct pt_regs *regs, int do_panic)
 513 {
 514         unsigned long flags;
 515
 516         if (notify_die(DIE_NMIWATCHDOG, str, regs, 0, 2, SIGINT) == NOTIFY_STOP)
 517                 return;
 518
 519         flags = oops_begin();
 520         /*
 521          * We are in trouble anyway, lets at least try
 522          * to get a message out.
 523          */
 524         printk(KERN_EMERG "%s", str);
 525         printk(" on CPU%d, ip %08lx, registers:\n",
 526                 smp_processor_id(), regs->ip);
 527         show_registers(regs);
 528         if (kexec_should_crash(current))
 529                 crash_kexec(regs);
 530         if (do_panic || panic_on_oops)
 531                 panic("Non maskable interrupt");
 532         oops_end(flags, NULL, SIGBUS);
 533         nmi_exit();
 534         local_irq_enable();
 535         do_exit(SIGBUS);
 536 }
 537
 538 static int __init oops_setup(char *s)
 539 {
 540         if (!s)
 541                 return -EINVAL;
 542         if (!strcmp(s, "panic"))
 543                 panic_on_oops = 1;
 544         return 0;
 545 }
 546 early_param("oops", oops_setup);
 547
 548 static int __init kstack_setup(char *s)
 549 {
 550         if (!s)
 551                 return -EINVAL;
 552         kstack_depth_to_print = simple_strtoul(s, NULL, 0);
 553         return 0;
 554 }
 555 early_param("kstack", kstack_setup);
 556
 557 static int __init code_bytes_setup(char *s)
 558 {
 559         code_bytes = simple_strtoul(s, NULL, 0);
 560         if (code_bytes > 8192)
 561                 code_bytes = 8192;
 562
 563         return 1;
 564 }
 565 __setup("code_bytes=", code_bytes_setup);