arch/x86/kernel/dumpstack_64.c

   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/hardirq.h>
   9 #include <linux/kdebug.h>
  10 #include <linux/module.h>
  11 #include <linux/ptrace.h>
  12 #include <linux/kexec.h>
  13 #include <linux/sysfs.h>
  14 #include <linux/bug.h>
  15 #include <linux/nmi.h>
  16
  17 #include <asm/stacktrace.h>
  18
  19
  20 #define N_EXCEPTION_STACKS_END \
  21                 (N_EXCEPTION_STACKS + DEBUG_STKSZ/EXCEPTION_STKSZ - 2)
  22
  23 static char x86_stack_ids[][8] = {
  24                 [ DEBUG_STACK-1                 ]       = "#DB",
  25                 [ NMI_STACK-1                   ]       = "NMI",
  26                 [ DOUBLEFAULT_STACK-1           ]       = "#DF",
  27                 [ MCE_STACK-1                   ]       = "#MC",
  28 #if DEBUG_STKSZ > EXCEPTION_STKSZ
  29                 [ N_EXCEPTION_STACKS ...
  30                   N_EXCEPTION_STACKS_END        ]       = "#DB[?]"
  31 #endif
  32 };
  33
  34 static unsigned long *in_exception_stack(unsigned cpu, unsigned long stack,
  35                                          unsigned *usedp, char **idp)
  36 {
  37         unsigned k;
  38
  39         /*
  40          * Iterate over all exception stacks, and figure out whether
  41          * 'stack' is in one of them:
  42          */
  43         for (k = 0; k < N_EXCEPTION_STACKS; k++) {
  44                 unsigned long end = per_cpu(orig_ist, cpu).ist[k];
  45                 /*
  46                  * Is 'stack' above this exception frame's end?
  47                  * If yes then skip to the next frame.
  48                  */
  49                 if (stack >= end)
  50                         continue;
  51                 /*
  52                  * Is 'stack' above this exception frame's start address?
  53                  * If yes then we found the right frame.
  54                  */
  55                 if (stack >= end - EXCEPTION_STKSZ) {
  56                         /*
  57                          * Make sure we only iterate through an exception
  58                          * stack once. If it comes up for the second time
  59                          * then there's something wrong going on - just
  60                          * break out and return NULL:
  61                          */
  62                         if (*usedp & (1U << k))
  63                                 break;
  64                         *usedp |= 1U << k;
  65                         *idp = x86_stack_ids[k];
  66                         return (unsigned long *)end;
  67                 }
  68                 /*
  69                  * If this is a debug stack, and if it has a larger size than
  70                  * the usual exception stacks, then 'stack' might still
  71                  * be within the lower portion of the debug stack:
  72                  */
  73 #if DEBUG_STKSZ > EXCEPTION_STKSZ
  74                 if (k == DEBUG_STACK - 1 && stack >= end - DEBUG_STKSZ) {
  75                         unsigned j = N_EXCEPTION_STACKS - 1;
  76
  77                         /*
  78                          * Black magic. A large debug stack is composed of
  79                          * multiple exception stack entries, which we
  80                          * iterate through now. Dont look:
  81                          */
  82                         do {
  83                                 ++j;
  84                                 end -= EXCEPTION_STKSZ;
  85                                 x86_stack_ids[j][4] = '1' +
  86                                                 (j - N_EXCEPTION_STACKS);
  87                         } while (stack < end - EXCEPTION_STKSZ);
  88                         if (*usedp & (1U << j))
  89                                 break;
  90                         *usedp |= 1U << j;
  91                         *idp = x86_stack_ids[j];
  92                         return (unsigned long *)end;
  93                 }
  94 #endif
  95         }
  96         return NULL;
  97 }
  98
  99 static inline int
 100 in_irq_stack(unsigned long *stack, unsigned long *irq_stack,
 101              unsigned long *irq_stack_end)
 102 {
 103         return (stack >= irq_stack && stack < irq_stack_end);
 104 }
 105
 106 /*
 107  * x86-64 can have up to three kernel stacks:
 108  * process stack
 109  * interrupt stack
 110  * severe exception (double fault, nmi, stack fault, debug, mce) hardware stack
 111  */
 112
 113 void dump_trace(struct task_struct *task, struct pt_regs *regs,
 114                 unsigned long *stack, unsigned long bp,
 115                 const struct stacktrace_ops *ops, void *data)
 116 {
 117         const unsigned cpu = get_cpu();
 118         unsigned long *irq_stack_end =
 119                 (unsigned long *)per_cpu(irq_stack_ptr, cpu);
 120         unsigned used = 0;
 121         struct thread_info *tinfo;
 122         int graph = 0;
 123         unsigned long dummy;
 124
 125         if (!task)
 126                 task = current;
 127
 128         if (!stack) {
 129                 if (regs)
 130                         stack = (unsigned long *)regs->sp;
 131                 else if (task && task != current)
 132                         stack = (unsigned long *)task->thread.sp;
 133                 else
 134                         stack = &dummy;
 135         }
 136
 137         if (!bp)
 138                 bp = stack_frame(task, regs);
 139         /*
 140          * Print function call entries in all stacks, starting at the
 141          * current stack address. If the stacks consist of nested
 142          * exceptions
 143          */
 144         tinfo = task_thread_info(task);
 145         for (;;) {
 146                 char *id;
 147                 unsigned long *estack_end;
 148                 estack_end = in_exception_stack(cpu, (unsigned long)stack,
 149                                                 &used, &id);
 150
 151                 if (estack_end) {
 152                         if (ops->stack(data, id) < 0)
 153                                 break;
 154
 155                         bp = ops->walk_stack(tinfo, stack, bp, ops,
 156                                              data, estack_end, &graph);
 157                         ops->stack(data, "<EOE>");
 158                         /*
 159                          * We link to the next stack via the
 160                          * second-to-last pointer (index -2 to end) in the
 161                          * exception stack:
 162                          */
 163                         stack = (unsigned long *) estack_end[-2];
 164                         continue;
 165                 }
 166                 if (irq_stack_end) {
 167                         unsigned long *irq_stack;
 168                         irq_stack = irq_stack_end -
 169                                 (IRQ_STACK_SIZE - 64) / sizeof(*irq_stack);
 170
 171                         if (in_irq_stack(stack, irq_stack, irq_stack_end)) {
 172                                 if (ops->stack(data, "IRQ") < 0)
 173                                         break;
 174                                 bp = ops->walk_stack(tinfo, stack, bp,
 175                                         ops, data, irq_stack_end, &graph);
 176                                 /*
 177                                  * We link to the next stack (which would be
 178                                  * the process stack normally) the last
 179                                  * pointer (index -1 to end) in the IRQ stack:
 180                                  */
 181                                 stack = (unsigned long *) (irq_stack_end[-1]);
 182                                 irq_stack_end = NULL;
 183                                 ops->stack(data, "EOI");
 184                                 continue;
 185                         }
 186                 }
 187                 break;
 188         }
 189
 190         /*
 191          * This handles the process stack:
 192          */
 193         bp = ops->walk_stack(tinfo, stack, bp, ops, data, NULL, &graph);
 194         put_cpu();
 195 }
 196 EXPORT_SYMBOL(dump_trace);
 197
 198 void
 199 show_stack_log_lvl(struct task_struct *task, struct pt_regs *regs,
 200                    unsigned long *sp, unsigned long bp, char *log_lvl)
 201 {
 202         unsigned long *irq_stack_end;
 203         unsigned long *irq_stack;
 204         unsigned long *stack;
 205         int cpu;
 206         int i;
 207
 208         preempt_disable();
 209         cpu = smp_processor_id();
 210
 211         irq_stack_end   = (unsigned long *)(per_cpu(irq_stack_ptr, cpu));
 212         irq_stack       = (unsigned long *)(per_cpu(irq_stack_ptr, cpu) - IRQ_STACK_SIZE);
 213
 214         /*
 215          * Debugging aid: "show_stack(NULL, NULL);" prints the
 216          * back trace for this cpu:
 217          */
 218         if (sp == NULL) {
 219                 if (task)
 220                         sp = (unsigned long *)task->thread.sp;
 221                 else
 222                         sp = (unsigned long *)&sp;
 223         }
 224
 225         stack = sp;
 226         for (i = 0; i < kstack_depth_to_print; i++) {
 227                 if (stack >= irq_stack && stack <= irq_stack_end) {
 228                         if (stack == irq_stack_end) {
 229                                 stack = (unsigned long *) (irq_stack_end[-1]);
 230                                 printk(KERN_CONT " <EOI> ");
 231                         }
 232                 } else {
 233                 if (((long) stack & (THREAD_SIZE-1)) == 0)
 234                         break;
 235                 }
 236                 if (i && ((i % STACKSLOTS_PER_LINE) == 0))
 237                         printk(KERN_CONT "\n");
 238                 printk(KERN_CONT " %016lx", *stack++);
 239                 touch_nmi_watchdog();
 240         }
 241         preempt_enable();
 242
 243         printk(KERN_CONT "\n");
 244         show_trace_log_lvl(task, regs, sp, bp, log_lvl);
 245 }
 246
 247 void show_registers(struct pt_regs *regs)
 248 {
 249         int i;
 250         unsigned long sp;
 251         const int cpu = smp_processor_id();
 252         struct task_struct *cur = current;
 253
 254         sp = regs->sp;
 255         printk("CPU %d ", cpu);
 256         print_modules();
 257         __show_regs(regs, 1);
 258         printk("Process %s (pid: %d, threadinfo %p, task %p)\n",
 259                 cur->comm, cur->pid, task_thread_info(cur), cur);
 260
 261         /*
 262          * When in-kernel, we also print out the stack and code at the
 263          * time of the fault..
 264          */
 265         if (!user_mode(regs)) {
 266                 unsigned int code_prologue = code_bytes * 43 / 64;
 267                 unsigned int code_len = code_bytes;
 268                 unsigned char c;
 269                 u8 *ip;
 270
 271                 printk(KERN_EMERG "Stack:\n");
 272                 show_stack_log_lvl(NULL, regs, (unsigned long *)sp,
 273                                    0, KERN_EMERG);
 274
 275                 printk(KERN_EMERG "Code: ");
 276
 277                 ip = (u8 *)regs->ip - code_prologue;
 278                 if (ip < (u8 *)PAGE_OFFSET || probe_kernel_address(ip, c)) {
 279                         /* try starting at IP */
 280                         ip = (u8 *)regs->ip;
 281                         code_len = code_len - code_prologue + 1;
 282                 }
 283                 for (i = 0; i < code_len; i++, ip++) {
 284                         if (ip < (u8 *)PAGE_OFFSET ||
 285                                         probe_kernel_address(ip, c)) {
 286                                 printk(KERN_CONT " Bad RIP value.");
 287                                 break;
 288                         }
 289                         if (ip == (u8 *)regs->ip)
 290                                 printk(KERN_CONT "<%02x> ", c);
 291                         else
 292                                 printk(KERN_CONT "%02x ", c);
 293                 }
 294         }
 295         printk(KERN_CONT "\n");
 296 }
 297
 298 int is_valid_bugaddr(unsigned long ip)
 299 {
 300         unsigned short ud2;
 301
 302         if (__copy_from_user(&ud2, (const void __user *) ip, sizeof(ud2)))
 303                 return 0;
 304
 305         return ud2 == 0x0b0f;
 306 }