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 <linux/unwind.h>
  18 #include <asm/stacktrace.h>
  19
  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 static unsigned long *in_exception_stack(unsigned cpu, unsigned long stack,
  37                                          unsigned *usedp, char **idp)
  38 {
  39         unsigned k;
  40
  41         /*
  42          * Iterate over all exception stacks, and figure out whether
  43          * 'stack' is in one of them:
  44          */
  45         for (k = 0; k < N_EXCEPTION_STACKS; k++) {
  46                 unsigned long end = per_cpu(orig_ist, cpu).ist[k];
  47                 /*
  48                  * Is 'stack' above this exception frame's end?
  49                  * If yes then skip to the next frame.
  50                  */
  51                 if (stack >= end)
  52                         continue;
  53                 /*
  54                  * Is 'stack' above this exception frame's start address?
  55                  * If yes then we found the right frame.
  56                  */
  57                 if (stack >= end - EXCEPTION_STKSZ) {
  58                         /*
  59                          * Make sure we only iterate through an exception
  60                          * stack once. If it comes up for the second time
  61                          * then there's something wrong going on - just
  62                          * break out and return NULL:
  63                          */
  64                         if (*usedp & (1U << k))
  65                                 break;
  66                         *usedp |= 1U << k;
  67                         *idp = x86_stack_ids[k];
  68                         return (unsigned long *)end;
  69                 }
  70                 /*
  71                  * If this is a debug stack, and if it has a larger size than
  72                  * the usual exception stacks, then 'stack' might still
  73                  * be within the lower portion of the debug stack:
  74                  */
  75 #if DEBUG_STKSZ > EXCEPTION_STKSZ
  76                 if (k == DEBUG_STACK - 1 && stack >= end - DEBUG_STKSZ) {
  77                         unsigned j = N_EXCEPTION_STACKS - 1;
  78
  79                         /*
  80                          * Black magic. A large debug stack is composed of
  81                          * multiple exception stack entries, which we
  82                          * iterate through now. Dont look:
  83                          */
  84                         do {
  85                                 ++j;
  86                                 end -= EXCEPTION_STKSZ;
  87                                 x86_stack_ids[j][4] = '1' +
  88                                                 (j - N_EXCEPTION_STACKS);
  89                         } while (stack < end - EXCEPTION_STKSZ);
  90                         if (*usedp & (1U << j))
  91                                 break;
  92                         *usedp |= 1U << j;
  93                         *idp = x86_stack_ids[j];
  94                         return (unsigned long *)end;
  95                 }
  96 #endif
  97         }
  98         return NULL;
  99 }
 100
 101 static inline int
 102 in_irq_stack(unsigned long *stack, unsigned long *irq_stack,
 103              unsigned long *irq_stack_end)
 104 {
 105         return (stack >= irq_stack && stack < irq_stack_end);
 106 }
 107
 108 /*
 109  * x86-64 can have up to three kernel stacks:
 110  * process stack
 111  * interrupt stack
 112  * severe exception (double fault, nmi, stack fault, debug, mce) hardware stack
 113  */
 114
 115 void dump_trace(struct task_struct *task, struct pt_regs *regs,
 116                 unsigned long *stack, unsigned long bp,
 117                 const struct stacktrace_ops *ops, void *data)
 118 {
 119         const unsigned cpu = get_cpu();
 120         unsigned long *irq_stack_end =
 121                 (unsigned long *)per_cpu(irq_stack_ptr, cpu);
 122         unsigned used = 0;
 123         struct thread_info *tinfo;
 124         int graph = 0;
 125         unsigned long dummy;
 126
 127         if (!task)
 128                 task = current;
 129
 130         bp = stack_frame(task, regs);
 131         if (try_stack_unwind(task, regs, &stack, &bp, ops, data)) {
 132                 put_cpu();
 133                 return;
 134         }
 135
 136         if (!stack) {
 137                 if (regs)
 138                         stack = (unsigned long *)regs->sp;
 139                 else if (task != current)
 140                         stack = (unsigned long *)task->thread.sp;
 141                 else
 142                         stack = &dummy;
 143         }
 144
 145         if (!bp)
 146                 bp = stack_frame(task, regs);
 147         /*
 148          * Print function call entries in all stacks, starting at the
 149          * current stack address. If the stacks consist of nested
 150          * exceptions
 151          */
 152         tinfo = task_thread_info(task);
 153         for (;;) {
 154                 char *id;
 155                 unsigned long *estack_end;
 156                 estack_end = in_exception_stack(cpu, (unsigned long)stack,
 157                                                 &used, &id);
 158
 159                 if (estack_end) {
 160                         if (ops->stack(data, id) < 0)
 161                                 break;
 162
 163                         bp = ops->walk_stack(tinfo, stack, bp, ops,
 164                                              data, estack_end, &graph);
 165                         ops->stack(data, "<EOE>");
 166                         /*
 167                          * We link to the next stack via the
 168                          * second-to-last pointer (index -2 to end) in the
 169                          * exception stack:
 170                          */
 171                         stack = (unsigned long *) estack_end[-2];
 172                         continue;
 173                 }
 174                 if (irq_stack_end) {
 175                         unsigned long *irq_stack;
 176                         irq_stack = irq_stack_end -
 177                                 (IRQ_STACK_SIZE - 64) / sizeof(*irq_stack);
 178
 179                         if (in_irq_stack(stack, irq_stack, irq_stack_end)) {
 180                                 if (ops->stack(data, "IRQ") < 0)
 181                                         break;
 182                                 bp = ops->walk_stack(tinfo, stack, bp,
 183                                         ops, data, irq_stack_end, &graph);
 184                                 /*
 185                                  * We link to the next stack (which would be
 186                                  * the process stack normally) the last
 187                                  * pointer (index -1 to end) in the IRQ stack:
 188                                  */
 189                                 stack = (unsigned long *) (irq_stack_end[-1]);
 190                                 irq_stack_end = NULL;
 191                                 ops->stack(data, "EOI");
 192                                 continue;
 193                         }
 194                 }
 195                 break;
 196         }
 197
 198         /*
 199          * This handles the process stack:
 200          */
 201         bp = ops->walk_stack(tinfo, stack, bp, ops, data, NULL, &graph);
 202         put_cpu();
 203 }
 204 EXPORT_SYMBOL(dump_trace);
 205
 206 void
 207 show_stack_log_lvl(struct task_struct *task, struct pt_regs *regs,
 208                    unsigned long *sp, unsigned long bp, char *log_lvl)
 209 {
 210         unsigned long *irq_stack_end;
 211         unsigned long *irq_stack;
 212         unsigned long *stack;
 213         int cpu;
 214         int i;
 215
 216         preempt_disable();
 217         cpu = smp_processor_id();
 218
 219         irq_stack_end   = (unsigned long *)(per_cpu(irq_stack_ptr, cpu));
 220         irq_stack       = (unsigned long *)(per_cpu(irq_stack_ptr, cpu) - IRQ_STACK_SIZE);
 221
 222         /*
 223          * Debugging aid: "show_stack(NULL, NULL);" prints the
 224          * back trace for this cpu:
 225          */
 226         if (sp == NULL) {
 227                 if (task)
 228                         sp = (unsigned long *)task->thread.sp;
 229                 else
 230                         sp = (unsigned long *)&sp;
 231         }
 232
 233         stack = sp;
 234         for (i = 0; i < kstack_depth_to_print; i++) {
 235                 if (stack >= irq_stack && stack <= irq_stack_end) {
 236                         if (stack == irq_stack_end) {
 237                                 stack = (unsigned long *) (irq_stack_end[-1]);
 238                                 printk(KERN_CONT " <EOI> ");
 239                         }
 240                 } else {
 241                 if (((long) stack & (THREAD_SIZE-1)) == 0)
 242                         break;
 243                 }
 244                 if (i && ((i % STACKSLOTS_PER_LINE) == 0))
 245                         printk(KERN_CONT "\n");
 246                 printk(KERN_CONT " %016lx", *stack++);
 247                 touch_nmi_watchdog();
 248         }
 249         preempt_enable();
 250
 251         printk(KERN_CONT "\n");
 252         show_trace_log_lvl(task, regs, sp, bp, log_lvl);
 253 }
 254
 255 void show_registers(struct pt_regs *regs)
 256 {
 257         int i;
 258         unsigned long sp;
 259         const int cpu = smp_processor_id();
 260         struct task_struct *cur = current;
 261
 262         sp = regs->sp;
 263         printk("CPU %d ", cpu);
 264         print_modules();
 265         __show_regs(regs, 1);
 266         printk("Process %s (pid: %d, threadinfo %p, task %p)\n",
 267                 cur->comm, cur->pid, task_thread_info(cur), cur);
 268
 269         /*
 270          * When in-kernel, we also print out the stack and code at the
 271          * time of the fault..
 272          */
 273         if (!user_mode(regs)) {
 274                 unsigned int code_prologue = code_bytes * 43 / 64;
 275                 unsigned int code_len = code_bytes;
 276                 unsigned char c;
 277                 u8 *ip;
 278
 279                 printk(KERN_DEFAULT "Stack:\n");
 280                 show_stack_log_lvl(NULL, regs, (unsigned long *)sp,
 281                                    0, KERN_DEFAULT);
 282
 283                 printk(KERN_DEFAULT "Code: ");
 284
 285                 ip = (u8 *)regs->ip - code_prologue;
 286                 if (ip < (u8 *)PAGE_OFFSET || probe_kernel_address(ip, c)) {
 287                         /* try starting at IP */
 288                         ip = (u8 *)regs->ip;
 289                         code_len = code_len - code_prologue + 1;
 290                 }
 291                 for (i = 0; i < code_len; i++, ip++) {
 292                         if (ip < (u8 *)PAGE_OFFSET ||
 293                                         probe_kernel_address(ip, c)) {
 294                                 printk(KERN_CONT " Bad RIP value.");
 295                                 break;
 296                         }
 297                         if (ip == (u8 *)regs->ip)
 298                                 printk(KERN_CONT "<%02x> ", c);
 299                         else
 300                                 printk(KERN_CONT "%02x ", c);
 301                 }
 302         }
 303         printk(KERN_CONT "\n");
 304 }
 305
 306 int is_valid_bugaddr(unsigned long ip)
 307 {
 308         unsigned short ud2;
 309
 310         if (__copy_from_user(&ud2, (const void __user *) ip, sizeof(ud2)))
 311                 return 0;
 312
 313         return ud2 == 0x0b0f;
 314 }