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/bug.h>
  14 #include <linux/nmi.h>
  15 #include <linux/sysfs.h>
  16
  17 #include <asm/stacktrace.h>
  18
  19 #include "dumpstack.h"
  20
  21
  22 static char x86_stack_ids[][8] = {
  23                 [DEBUG_STACK - 1] = "#DB",
  24                 [NMI_STACK - 1] = "NMI",
  25                 [DOUBLEFAULT_STACK - 1] = "#DF",
  26                 [STACKFAULT_STACK - 1] = "#SS",
  27                 [MCE_STACK - 1] = "#MC",
  28 #if DEBUG_STKSZ > EXCEPTION_STKSZ
  29                 [N_EXCEPTION_STACKS ...
  30                         N_EXCEPTION_STACKS + DEBUG_STKSZ / EXCEPTION_STKSZ - 2] = "#DB[?]"
  31 #endif
  32         };
  33
  34 int x86_is_stack_id(int id, char *name)
  35 {
  36         return x86_stack_ids[id - 1] == name;
  37 }
  38
  39 static unsigned long *in_exception_stack(unsigned cpu, unsigned long stack,
  40                                         unsigned *usedp, char **idp)
  41 {
  42         unsigned k;
  43
  44         /*
  45          * Iterate over all exception stacks, and figure out whether
  46          * 'stack' is in one of them:
  47          */
  48         for (k = 0; k < N_EXCEPTION_STACKS; k++) {
  49                 unsigned long end = per_cpu(orig_ist, cpu).ist[k];
  50                 /*
  51                  * Is 'stack' above this exception frame's end?
  52                  * If yes then skip to the next frame.
  53                  */
  54                 if (stack >= end)
  55                         continue;
  56                 /*
  57                  * Is 'stack' above this exception frame's start address?
  58                  * If yes then we found the right frame.
  59                  */
  60                 if (stack >= end - EXCEPTION_STKSZ) {
  61                         /*
  62                          * Make sure we only iterate through an exception
  63                          * stack once. If it comes up for the second time
  64                          * then there's something wrong going on - just
  65                          * break out and return NULL:
  66                          */
  67                         if (*usedp & (1U << k))
  68                                 break;
  69                         *usedp |= 1U << k;
  70                         *idp = x86_stack_ids[k];
  71                         return (unsigned long *)end;
  72                 }
  73                 /*
  74                  * If this is a debug stack, and if it has a larger size than
  75                  * the usual exception stacks, then 'stack' might still
  76                  * be within the lower portion of the debug stack:
  77                  */
  78 #if DEBUG_STKSZ > EXCEPTION_STKSZ
  79                 if (k == DEBUG_STACK - 1 && stack >= end - DEBUG_STKSZ) {
  80                         unsigned j = N_EXCEPTION_STACKS - 1;
  81
  82                         /*
  83                          * Black magic. A large debug stack is composed of
  84                          * multiple exception stack entries, which we
  85                          * iterate through now. Dont look:
  86                          */
  87                         do {
  88                                 ++j;
  89                                 end -= EXCEPTION_STKSZ;
  90                                 x86_stack_ids[j][4] = '1' +
  91                                                 (j - N_EXCEPTION_STACKS);
  92                         } while (stack < end - EXCEPTION_STKSZ);
  93                         if (*usedp & (1U << j))
  94                                 break;
  95                         *usedp |= 1U << j;
  96                         *idp = x86_stack_ids[j];
  97                         return (unsigned long *)end;
  98                 }
  99 #endif
 100         }
 101         return NULL;
 102 }
 103
 104 /*
 105  * x86-64 can have up to three kernel stacks:
 106  * process stack
 107  * interrupt stack
 108  * severe exception (double fault, nmi, stack fault, debug, mce) hardware stack
 109  */
 110
 111 void dump_trace(struct task_struct *task, struct pt_regs *regs,
 112                 unsigned long *stack, unsigned long bp,
 113                 const struct stacktrace_ops *ops, void *data)
 114 {
 115         const unsigned cpu = get_cpu();
 116         unsigned long *irq_stack_end =
 117                 (unsigned long *)per_cpu(irq_stack_ptr, cpu);
 118         unsigned used = 0;
 119         struct thread_info *tinfo;
 120         int graph = 0;
 121
 122         if (!task)
 123                 task = current;
 124
 125         if (!stack) {
 126                 unsigned long dummy;
 127                 stack = &dummy;
 128                 if (task && task != current)
 129                         stack = (unsigned long *)task->thread.sp;
 130         }
 131
 132 #ifdef CONFIG_FRAME_POINTER
 133         if (!bp) {
 134                 if (task == current) {
 135                         /* Grab bp right from our regs */
 136                         get_bp(bp);
 137                 } else {
 138                         /* bp is the last reg pushed by switch_to */
 139                         bp = *(unsigned long *) task->thread.sp;
 140                 }
 141         }
 142 #endif
 143
 144         /*
 145          * Print function call entries in all stacks, starting at the
 146          * current stack address. If the stacks consist of nested
 147          * exceptions
 148          */
 149         tinfo = task_thread_info(task);
 150         for (;;) {
 151                 char *id;
 152                 unsigned long *estack_end;
 153                 estack_end = in_exception_stack(cpu, (unsigned long)stack,
 154                                                 &used, &id);
 155
 156                 if (estack_end) {
 157                         if (ops->stack(data, id) < 0)
 158                                 break;
 159
 160                         bp = print_context_stack(tinfo, stack, bp, ops,
 161                                                  data, estack_end, &graph);
 162                         ops->stack(data, "<EOE>");
 163                         /*
 164                          * We link to the next stack via the
 165                          * second-to-last pointer (index -2 to end) in the
 166                          * exception stack:
 167                          */
 168                         stack = (unsigned long *) estack_end[-2];
 169                         continue;
 170                 }
 171                 if (irq_stack_end) {
 172                         unsigned long *irq_stack;
 173                         irq_stack = irq_stack_end -
 174                                 (IRQ_STACK_SIZE - 64) / sizeof(*irq_stack);
 175
 176                         if (stack >= irq_stack && stack < irq_stack_end) {
 177                                 if (ops->stack(data, "IRQ") < 0)
 178                                         break;
 179                                 bp = print_context_stack(tinfo, stack, bp,
 180                                         ops, data, irq_stack_end, &graph);
 181                                 /*
 182                                  * We link to the next stack (which would be
 183                                  * the process stack normally) the last
 184                                  * pointer (index -1 to end) in the IRQ stack:
 185                                  */
 186                                 stack = (unsigned long *) (irq_stack_end[-1]);
 187                                 irq_stack_end = NULL;
 188                                 ops->stack(data, "EOI");
 189                                 continue;
 190                         }
 191                 }
 192                 break;
 193         }
 194
 195         /*
 196          * This handles the process stack:
 197          */
 198         bp = print_context_stack(tinfo, stack, bp, ops, data, NULL, &graph);
 199         put_cpu();
 200 }
 201 EXPORT_SYMBOL(dump_trace);
 202
 203 void
 204 show_stack_log_lvl(struct task_struct *task, struct pt_regs *regs,
 205                 unsigned long *sp, unsigned long bp, char *log_lvl)
 206 {
 207         unsigned long *stack;
 208         int i;
 209         const int cpu = smp_processor_id();
 210         unsigned long *irq_stack_end =
 211                 (unsigned long *)(per_cpu(irq_stack_ptr, cpu));
 212         unsigned long *irq_stack =
 213                 (unsigned long *)(per_cpu(irq_stack_ptr, cpu) - IRQ_STACK_SIZE);
 214
 215         /*
 216          * debugging aid: "show_stack(NULL, NULL);" prints the
 217          * back trace for this cpu.
 218          */
 219
 220         if (sp == NULL) {
 221                 if (task)
 222                         sp = (unsigned long *)task->thread.sp;
 223                 else
 224                         sp = (unsigned long *)&sp;
 225         }
 226
 227         stack = sp;
 228         for (i = 0; i < kstack_depth_to_print; i++) {
 229                 if (stack >= irq_stack && stack <= irq_stack_end) {
 230                         if (stack == irq_stack_end) {
 231                                 stack = (unsigned long *) (irq_stack_end[-1]);
 232                                 printk(" <EOI> ");
 233                         }
 234                 } else {
 235                 if (((long) stack & (THREAD_SIZE-1)) == 0)
 236                         break;
 237                 }
 238                 if (i && ((i % STACKSLOTS_PER_LINE) == 0))
 239                         printk("\n%s", log_lvl);
 240                 printk(" %016lx", *stack++);
 241                 touch_nmi_watchdog();
 242         }
 243         printk("\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         __show_regs(regs, 1);
 257         printk("Process %s (pid: %d, threadinfo %p, task %p)\n",
 258                 cur->comm, cur->pid, task_thread_info(cur), cur);
 259
 260         /*
 261          * When in-kernel, we also print out the stack and code at the
 262          * time of the fault..
 263          */
 264         if (!user_mode(regs)) {
 265                 unsigned int code_prologue = code_bytes * 43 / 64;
 266                 unsigned int code_len = code_bytes;
 267                 unsigned char c;
 268                 u8 *ip;
 269
 270                 printk(KERN_EMERG "Stack:\n");
 271                 show_stack_log_lvl(NULL, regs, (unsigned long *)sp,
 272                                 regs->bp, KERN_EMERG);
 273
 274                 printk(KERN_EMERG "Code: ");
 275
 276                 ip = (u8 *)regs->ip - code_prologue;
 277                 if (ip < (u8 *)PAGE_OFFSET || probe_kernel_address(ip, c)) {
 278                         /* try starting at IP */
 279                         ip = (u8 *)regs->ip;
 280                         code_len = code_len - code_prologue + 1;
 281                 }
 282                 for (i = 0; i < code_len; i++, ip++) {
 283                         if (ip < (u8 *)PAGE_OFFSET ||
 284                                         probe_kernel_address(ip, c)) {
 285                                 printk(" Bad RIP value.");
 286                                 break;
 287                         }
 288                         if (ip == (u8 *)regs->ip)
 289                                 printk("<%02x> ", c);
 290                         else
 291                                 printk("%02x ", c);
 292                 }
 293         }
 294         printk("\n");
 295 }
 296
 297 int is_valid_bugaddr(unsigned long ip)
 298 {
 299         unsigned short ud2;
 300
 301         if (__copy_from_user(&ud2, (const void __user *) ip, sizeof(ud2)))
 302                 return 0;
 303
 304         return ud2 == 0x0b0f;
 305 }
 306