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