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 #include "dumpstack.h"
  20
  21 #define N_EXCEPTION_STACKS_END \
  22                 (N_EXCEPTION_STACKS + DEBUG_STKSZ/EXCEPTION_STKSZ - 2)
  23
  24 static char x86_stack_ids[][8] = {
  25                 [ DEBUG_STACK-1                 ]       = "#DB",
  26                 [ NMI_STACK-1                   ]       = "NMI",
  27                 [ DOUBLEFAULT_STACK-1           ]       = "#DF",
  28                 [ STACKFAULT_STACK-1            ]       = "#SS",
  29                 [ MCE_STACK-1                   ]       = "#MC",
  30 #if DEBUG_STKSZ > EXCEPTION_STKSZ
  31                 [ N_EXCEPTION_STACKS ...
  32                   N_EXCEPTION_STACKS_END        ]       = "#DB[?]"
  33 #endif
  34 };
  35
  36 int x86_is_stack_id(int id, char *name)
  37 {
  38         return x86_stack_ids[id - 1] == name;
  39 }
  40
  41 static unsigned long *in_exception_stack(unsigned cpu, unsigned long stack,
  42                                          unsigned *usedp, char **idp)
  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 = x86_stack_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                                 x86_stack_ids[j][4] = '1' +
  93                                                 (j - N_EXCEPTION_STACKS);
  94                         } while (stack < end - EXCEPTION_STKSZ);
  95                         if (*usedp & (1U << j))
  96                                 break;
  97                         *usedp |= 1U << j;
  98                         *idp = x86_stack_ids[j];
  99                         return (unsigned long *)end;
 100                 }
 101 #endif
 102         }
 103         return NULL;
 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
 124         if (!task)
 125                 task = current;
 126
 127         if (!stack) {
 128                 unsigned long dummy;
 129                 stack = &dummy;
 130                 if (task && task != current)
 131                         stack = (unsigned long *)task->thread.sp;
 132         }
 133
 134 #ifdef CONFIG_FRAME_POINTER
 135         if (!bp) {
 136                 if (task == current) {
 137                         /* Grab bp right from our regs */
 138                         get_bp(bp);
 139                 } else {
 140                         /* bp is the last reg pushed by switch_to */
 141                         bp = *(unsigned long *) task->thread.sp;
 142                 }
 143         }
 144 #endif
 145
 146         /*
 147          * Print function call entries in all stacks, starting at the
 148          * current stack address. If the stacks consist of nested
 149          * exceptions
 150          */
 151         tinfo = task_thread_info(task);
 152         for (;;) {
 153                 char *id;
 154                 unsigned long *estack_end;
 155                 estack_end = in_exception_stack(cpu, (unsigned long)stack,
 156                                                 &used, &id);
 157
 158                 if (estack_end) {
 159                         if (ops->stack(data, id) < 0)
 160                                 break;
 161
 162                         bp = print_context_stack(tinfo, stack, bp, ops,
 163                                                  data, estack_end, &graph);
 164                         ops->stack(data, "<EOE>");
 165                         /*
 166                          * We link to the next stack via the
 167                          * second-to-last pointer (index -2 to end) in the
 168                          * exception stack:
 169                          */
 170                         stack = (unsigned long *) estack_end[-2];
 171                         continue;
 172                 }
 173                 if (irq_stack_end) {
 174                         unsigned long *irq_stack;
 175                         irq_stack = irq_stack_end -
 176                                 (IRQ_STACK_SIZE - 64) / sizeof(*irq_stack);
 177
 178                         if (stack >= irq_stack && stack < irq_stack_end) {
 179                                 if (ops->stack(data, "IRQ") < 0)
 180                                         break;
 181                                 bp = print_context_stack(tinfo, stack, bp,
 182                                         ops, data, irq_stack_end, &graph);
 183                                 /*
 184                                  * We link to the next stack (which would be
 185                                  * the process stack normally) the last
 186                                  * pointer (index -1 to end) in the IRQ stack:
 187                                  */
 188                                 stack = (unsigned long *) (irq_stack_end[-1]);
 189                                 irq_stack_end = NULL;
 190                                 ops->stack(data, "EOI");
 191                                 continue;
 192                         }
 193                 }
 194                 break;
 195         }
 196
 197         /*
 198          * This handles the process stack:
 199          */
 200         bp = print_context_stack(tinfo, stack, bp, ops, data, NULL, &graph);
 201         put_cpu();
 202 }
 203 EXPORT_SYMBOL(dump_trace);
 204
 205 void
 206 show_stack_log_lvl(struct task_struct *task, struct pt_regs *regs,
 207                    unsigned long *sp, unsigned long bp, char *log_lvl)
 208 {
 209         unsigned long *irq_stack_end;
 210         unsigned long *irq_stack;
 211         unsigned long *stack;
 212         int cpu;
 213         int i;
 214
 215         preempt_disable();
 216         cpu = smp_processor_id();
 217
 218         irq_stack_end   = (unsigned long *)(per_cpu(irq_stack_ptr, cpu));
 219         irq_stack       = (unsigned long *)(per_cpu(irq_stack_ptr, cpu) - IRQ_STACK_SIZE);
 220
 221         /*
 222          * Debugging aid: "show_stack(NULL, NULL);" prints the
 223          * back trace for this cpu:
 224          */
 225         if (sp == NULL) {
 226                 if (task)
 227                         sp = (unsigned long *)task->thread.sp;
 228                 else
 229                         sp = (unsigned long *)&sp;
 230         }
 231
 232         stack = sp;
 233         for (i = 0; i < kstack_depth_to_print; i++) {
 234                 if (stack >= irq_stack && stack <= irq_stack_end) {
 235                         if (stack == irq_stack_end) {
 236                                 stack = (unsigned long *) (irq_stack_end[-1]);
 237                                 printk(" <EOI> ");
 238                         }
 239                 } else {
 240                 if (((long) stack & (THREAD_SIZE-1)) == 0)
 241                         break;
 242                 }
 243                 if (i && ((i % STACKSLOTS_PER_LINE) == 0))
 244                         printk("\n%s", log_lvl);
 245                 printk(" %016lx", *stack++);
 246                 touch_nmi_watchdog();
 247         }
 248         preempt_enable();
 249
 250         printk("\n");
 251         show_trace_log_lvl(task, regs, sp, bp, log_lvl);
 252 }
 253
 254 void show_registers(struct pt_regs *regs)
 255 {
 256         int i;
 257         unsigned long sp;
 258         const int cpu = smp_processor_id();
 259         struct task_struct *cur = current;
 260
 261         sp = regs->sp;
 262         printk("CPU %d ", cpu);
 263         __show_regs(regs, 1);
 264         printk("Process %s (pid: %d, threadinfo %p, task %p)\n",
 265                 cur->comm, cur->pid, task_thread_info(cur), cur);
 266
 267         /*
 268          * When in-kernel, we also print out the stack and code at the
 269          * time of the fault..
 270          */
 271         if (!user_mode(regs)) {
 272                 unsigned int code_prologue = code_bytes * 43 / 64;
 273                 unsigned int code_len = code_bytes;
 274                 unsigned char c;
 275                 u8 *ip;
 276
 277                 printk(KERN_EMERG "Stack:\n");
 278                 show_stack_log_lvl(NULL, regs, (unsigned long *)sp,
 279                                 regs->bp, KERN_EMERG);
 280
 281                 printk(KERN_EMERG "Code: ");
 282
 283                 ip = (u8 *)regs->ip - code_prologue;
 284                 if (ip < (u8 *)PAGE_OFFSET || probe_kernel_address(ip, c)) {
 285                         /* try starting at IP */
 286                         ip = (u8 *)regs->ip;
 287                         code_len = code_len - code_prologue + 1;
 288                 }
 289                 for (i = 0; i < code_len; i++, ip++) {
 290                         if (ip < (u8 *)PAGE_OFFSET ||
 291                                         probe_kernel_address(ip, c)) {
 292                                 printk(" Bad RIP value.");
 293                                 break;
 294                         }
 295                         if (ip == (u8 *)regs->ip)
 296                                 printk("<%02x> ", c);
 297                         else
 298                                 printk("%02x ", c);
 299                 }
 300         }
 301         printk("\n");
 302 }
 303
 304 int is_valid_bugaddr(unsigned long ip)
 305 {
 306         unsigned short ud2;
 307
 308         if (__copy_from_user(&ud2, (const void __user *) ip, sizeof(ud2)))
 309                 return 0;
 310
 311         return ud2 == 0x0b0f;
 312 }