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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 #include <linux/sysfs.h>
  17
  18 #include <asm/stacktrace.h>
  19
  20 #include "dumpstack.h"
  21
  22 static unsigned long *in_exception_stack(unsigned cpu, unsigned long stack,
  23                                         unsigned *usedp, char **idp)
  24 {
  25         static char ids[][8] = {
  26                 [DEBUG_STACK - 1] = "#DB",
  27                 [NMI_STACK - 1] = "NMI",
  28                 [DOUBLEFAULT_STACK - 1] = "#DF",
  29                 [STACKFAULT_STACK - 1] = "#SS",
  30                 [MCE_STACK - 1] = "#MC",
  31 #if DEBUG_STKSZ > EXCEPTION_STKSZ
  32                 [N_EXCEPTION_STACKS ...
  33                         N_EXCEPTION_STACKS + DEBUG_STKSZ / EXCEPTION_STKSZ - 2] = "#DB[?]"
  34 #endif
  35         };
  36         unsigned k;
  37
  38         /*
  39          * Iterate over all exception stacks, and figure out whether
  40          * 'stack' is in one of them:
  41          */
  42         for (k = 0; k < N_EXCEPTION_STACKS; k++) {
  43                 unsigned long end = per_cpu(orig_ist, cpu).ist[k];
  44                 /*
  45                  * Is 'stack' above this exception frame's end?
  46                  * If yes then skip to the next frame.
  47                  */
  48                 if (stack >= end)
  49                         continue;
  50                 /*
  51                  * Is 'stack' above this exception frame's start address?
  52                  * If yes then we found the right frame.
  53                  */
  54                 if (stack >= end - EXCEPTION_STKSZ) {
  55                         /*
  56                          * Make sure we only iterate through an exception
  57                          * stack once. If it comes up for the second time
  58                          * then there's something wrong going on - just
  59                          * break out and return NULL:
  60                          */
  61                         if (*usedp & (1U << k))
  62                                 break;
  63                         *usedp |= 1U << k;
  64                         *idp = ids[k];
  65                         return (unsigned long *)end;
  66                 }
  67                 /*
  68                  * If this is a debug stack, and if it has a larger size than
  69                  * the usual exception stacks, then 'stack' might still
  70                  * be within the lower portion of the debug stack:
  71                  */
  72 #if DEBUG_STKSZ > EXCEPTION_STKSZ
  73                 if (k == DEBUG_STACK - 1 && stack >= end - DEBUG_STKSZ) {
  74                         unsigned j = N_EXCEPTION_STACKS - 1;
  75
  76                         /*
  77                          * Black magic. A large debug stack is composed of
  78                          * multiple exception stack entries, which we
  79                          * iterate through now. Dont look:
  80                          */
  81                         do {
  82                                 ++j;
  83                                 end -= EXCEPTION_STKSZ;
  84                                 ids[j][4] = '1' + (j - N_EXCEPTION_STACKS);
  85                         } while (stack < end - EXCEPTION_STKSZ);
  86                         if (*usedp & (1U << j))
  87                                 break;
  88                         *usedp |= 1U << j;
  89                         *idp = ids[j];
  90                         return (unsigned long *)end;
  91                 }
  92 #endif
  93         }
  94         return NULL;
  95 }
  96
  97 /*
  98  * x86-64 can have up to three kernel stacks:
  99  * process stack
 100  * interrupt stack
 101  * severe exception (double fault, nmi, stack fault, debug, mce) hardware stack
 102  */
 103
 104 void dump_trace(struct task_struct *task, struct pt_regs *regs,
 105                 unsigned long *stack, unsigned long bp,
 106                 const struct stacktrace_ops *ops, void *data)
 107 {
 108         const unsigned cpu = get_cpu();
 109         unsigned long *irqstack_end = (unsigned long *)cpu_pda(cpu)->irqstackptr;
 110         unsigned used = 0;
 111         struct thread_info *tinfo;
 112         int graph = 0;
 113
 114         if (!task)
 115                 task = current;
 116
 117         if (!stack) {
 118                 unsigned long dummy;
 119                 stack = &dummy;
 120                 if (task && task != current)
 121                         stack = (unsigned long *)task->thread.sp;
 122         }
 123
 124 #ifdef CONFIG_FRAME_POINTER
 125         if (!bp) {
 126                 if (task == current) {
 127                         /* Grab bp right from our regs */
 128                         get_bp(bp);
 129                 } else {
 130                         /* bp is the last reg pushed by switch_to */
 131                         bp = *(unsigned long *) task->thread.sp;
 132                 }
 133         }
 134 #endif
 135
 136         /*
 137          * Print function call entries in all stacks, starting at the
 138          * current stack address. If the stacks consist of nested
 139          * exceptions
 140          */
 141         tinfo = task_thread_info(task);
 142         for (;;) {
 143                 char *id;
 144                 unsigned long *estack_end;
 145                 estack_end = in_exception_stack(cpu, (unsigned long)stack,
 146                                                 &used, &id);
 147
 148                 if (estack_end) {
 149                         if (ops->stack(data, id) < 0)
 150                                 break;
 151
 152                         bp = print_context_stack(tinfo, stack, bp, ops,
 153                                                  data, estack_end, &graph);
 154                         ops->stack(data, "<EOE>");
 155                         /*
 156                          * We link to the next stack via the
 157                          * second-to-last pointer (index -2 to end) in the
 158                          * exception stack:
 159                          */
 160                         stack = (unsigned long *) estack_end[-2];
 161                         continue;
 162                 }
 163                 if (irqstack_end) {
 164                         unsigned long *irqstack;
 165                         irqstack = irqstack_end -
 166                                 (IRQSTACKSIZE - 64) / sizeof(*irqstack);
 167
 168                         if (stack >= irqstack && stack < irqstack_end) {
 169                                 if (ops->stack(data, "IRQ") < 0)
 170                                         break;
 171                                 bp = print_context_stack(tinfo, stack, bp,
 172                                         ops, data, irqstack_end, &graph);
 173                                 /*
 174                                  * We link to the next stack (which would be
 175                                  * the process stack normally) the last
 176                                  * pointer (index -1 to end) in the IRQ stack:
 177                                  */
 178                                 stack = (unsigned long *) (irqstack_end[-1]);
 179                                 irqstack_end = NULL;
 180                                 ops->stack(data, "EOI");
 181                                 continue;
 182                         }
 183                 }
 184                 break;
 185         }
 186
 187         /*
 188          * This handles the process stack:
 189          */
 190         bp = print_context_stack(tinfo, stack, bp, ops, data, NULL, &graph);
 191         put_cpu();
 192 }
 193 EXPORT_SYMBOL(dump_trace);
 194
 195 void
 196 show_stack_log_lvl(struct task_struct *task, struct pt_regs *regs,
 197                 unsigned long *sp, unsigned long bp, char *log_lvl)
 198 {
 199         unsigned long *stack;
 200         int i;
 201         const int cpu = smp_processor_id();
 202         unsigned long *irqstack_end =
 203                 (unsigned long *) (cpu_pda(cpu)->irqstackptr);
 204         unsigned long *irqstack =
 205                 (unsigned long *) (cpu_pda(cpu)->irqstackptr - IRQSTACKSIZE);
 206
 207         /*
 208          * debugging aid: "show_stack(NULL, NULL);" prints the
 209          * back trace for this cpu.
 210          */
 211
 212         if (sp == NULL) {
 213                 if (task)
 214                         sp = (unsigned long *)task->thread.sp;
 215                 else
 216                         sp = (unsigned long *)&sp;
 217         }
 218
 219         stack = sp;
 220         for (i = 0; i < kstack_depth_to_print; i++) {
 221                 if (stack >= irqstack && stack <= irqstack_end) {
 222                         if (stack == irqstack_end) {
 223                                 stack = (unsigned long *) (irqstack_end[-1]);
 224                                 printk(" <EOI> ");
 225                         }
 226                 } else {
 227                 if (((long) stack & (THREAD_SIZE-1)) == 0)
 228                         break;
 229                 }
 230                 if (i && ((i % STACKSLOTS_PER_LINE) == 0))
 231                         printk("\n%s", log_lvl);
 232                 printk(" %016lx", *stack++);
 233                 touch_nmi_watchdog();
 234         }
 235         printk("\n");
 236         show_trace_log_lvl(task, regs, sp, bp, log_lvl);
 237 }
 238
 239 void show_registers(struct pt_regs *regs)
 240 {
 241         int i;
 242         unsigned long sp;
 243         const int cpu = smp_processor_id();
 244         struct task_struct *cur = cpu_pda(cpu)->pcurrent;
 245
 246         sp = regs->sp;
 247         printk("CPU %d ", cpu);
 248         __show_regs(regs, 1);
 249         printk("Process %s (pid: %d, threadinfo %p, task %p)\n",
 250                 cur->comm, cur->pid, task_thread_info(cur), cur);
 251
 252         /*
 253          * When in-kernel, we also print out the stack and code at the
 254          * time of the fault..
 255          */
 256         if (!user_mode(regs)) {
 257                 unsigned int code_prologue = code_bytes * 43 / 64;
 258                 unsigned int code_len = code_bytes;
 259                 unsigned char c;
 260                 u8 *ip;
 261
 262                 printk(KERN_EMERG "Stack:\n");
 263                 show_stack_log_lvl(NULL, regs, (unsigned long *)sp,
 264                                 regs->bp, KERN_EMERG);
 265
 266                 printk(KERN_EMERG "Code: ");
 267
 268                 ip = (u8 *)regs->ip - code_prologue;
 269                 if (ip < (u8 *)PAGE_OFFSET || probe_kernel_address(ip, c)) {
 270                         /* try starting at IP */
 271                         ip = (u8 *)regs->ip;
 272                         code_len = code_len - code_prologue + 1;
 273                 }
 274                 for (i = 0; i < code_len; i++, ip++) {
 275                         if (ip < (u8 *)PAGE_OFFSET ||
 276                                         probe_kernel_address(ip, c)) {
 277                                 printk(" Bad RIP value.");
 278                                 break;
 279                         }
 280                         if (ip == (u8 *)regs->ip)
 281                                 printk("<%02x> ", c);
 282                         else
 283                                 printk("%02x ", c);
 284                 }
 285         }
 286         printk("\n");
 287 }
 288
 289 int is_valid_bugaddr(unsigned long ip)
 290 {
 291         unsigned short ud2;
 292
 293         if (__copy_from_user(&ud2, (const void __user *) ip, sizeof(ud2)))
 294                 return 0;
 295
 296         return ud2 == 0x0b0f;
 297 }
 298