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   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 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  * We are returning from the irq stack and go to the previous one.
 110  * If the previous stack is also in the irq stack, then bp in the first
 111  * frame of the irq stack points to the previous, interrupted one.
 112  * Otherwise we have another level of indirection: We first save
 113  * the bp of the previous stack, then we switch the stack to the irq one
 114  * and save a new bp that links to the previous one.
 115  * (See save_args())
 116  */
 117 static inline unsigned long
 118 fixup_bp_irq_link(unsigned long bp, unsigned long *stack,
 119                   unsigned long *irq_stack, unsigned long *irq_stack_end)
 120 {
 121 #ifdef CONFIG_FRAME_POINTER
 122         struct stack_frame *frame = (struct stack_frame *)bp;
 123
 124         if (!in_irq_stack(stack, irq_stack, irq_stack_end))
 125                 return (unsigned long)frame->next_frame;
 126 #endif
 127         return bp;
 128 }
 129
 130 /*
 131  * x86-64 can have up to three kernel stacks:
 132  * process stack
 133  * interrupt stack
 134  * severe exception (double fault, nmi, stack fault, debug, mce) hardware stack
 135  */
 136
 137 void dump_trace(struct task_struct *task, struct pt_regs *regs,
 138                 unsigned long *stack, unsigned long bp,
 139                 const struct stacktrace_ops *ops, void *data)
 140 {
 141         const unsigned cpu = get_cpu();
 142         unsigned long *irq_stack_end =
 143                 (unsigned long *)per_cpu(irq_stack_ptr, cpu);
 144         unsigned used = 0;
 145         struct thread_info *tinfo;
 146         int graph = 0;
 147
 148         if (!task)
 149                 task = current;
 150
 151         if (!stack) {
 152                 unsigned long dummy;
 153                 stack = &dummy;
 154                 if (task && task != current)
 155                         stack = (unsigned long *)task->thread.sp;
 156         }
 157
 158 #ifdef CONFIG_FRAME_POINTER
 159         if (!bp) {
 160                 if (task == current) {
 161                         /* Grab bp right from our regs */
 162                         get_bp(bp);
 163                 } else {
 164                         /* bp is the last reg pushed by switch_to */
 165                         bp = *(unsigned long *) task->thread.sp;
 166                 }
 167         }
 168 #endif
 169
 170         /*
 171          * Print function call entries in all stacks, starting at the
 172          * current stack address. If the stacks consist of nested
 173          * exceptions
 174          */
 175         tinfo = task_thread_info(task);
 176         for (;;) {
 177                 char *id;
 178                 unsigned long *estack_end;
 179                 estack_end = in_exception_stack(cpu, (unsigned long)stack,
 180                                                 &used, &id);
 181
 182                 if (estack_end) {
 183                         if (ops->stack(data, id) < 0)
 184                                 break;
 185
 186                         bp = ops->walk_stack(tinfo, stack, bp, ops,
 187                                              data, estack_end, &graph);
 188                         ops->stack(data, "<EOE>");
 189                         /*
 190                          * We link to the next stack via the
 191                          * second-to-last pointer (index -2 to end) in the
 192                          * exception stack:
 193                          */
 194                         stack = (unsigned long *) estack_end[-2];
 195                         continue;
 196                 }
 197                 if (irq_stack_end) {
 198                         unsigned long *irq_stack;
 199                         irq_stack = irq_stack_end -
 200                                 (IRQ_STACK_SIZE - 64) / sizeof(*irq_stack);
 201
 202                         if (in_irq_stack(stack, irq_stack, irq_stack_end)) {
 203                                 if (ops->stack(data, "IRQ") < 0)
 204                                         break;
 205                                 bp = print_context_stack(tinfo, stack, bp,
 206                                         ops, data, irq_stack_end, &graph);
 207                                 /*
 208                                  * We link to the next stack (which would be
 209                                  * the process stack normally) the last
 210                                  * pointer (index -1 to end) in the IRQ stack:
 211                                  */
 212                                 stack = (unsigned long *) (irq_stack_end[-1]);
 213                                 bp = fixup_bp_irq_link(bp, stack, irq_stack,
 214                                                        irq_stack_end);
 215                                 irq_stack_end = NULL;
 216                                 ops->stack(data, "EOI");
 217                                 continue;
 218                         }
 219                 }
 220                 break;
 221         }
 222
 223         /*
 224          * This handles the process stack:
 225          */
 226         bp = print_context_stack(tinfo, stack, bp, ops, data, NULL, &graph);
 227         put_cpu();
 228 }
 229 EXPORT_SYMBOL(dump_trace);
 230
 231 void
 232 show_stack_log_lvl(struct task_struct *task, struct pt_regs *regs,
 233                    unsigned long *sp, unsigned long bp, char *log_lvl)
 234 {
 235         unsigned long *irq_stack_end;
 236         unsigned long *irq_stack;
 237         unsigned long *stack;
 238         int cpu;
 239         int i;
 240
 241         preempt_disable();
 242         cpu = smp_processor_id();
 243
 244         irq_stack_end   = (unsigned long *)(per_cpu(irq_stack_ptr, cpu));
 245         irq_stack       = (unsigned long *)(per_cpu(irq_stack_ptr, cpu) - IRQ_STACK_SIZE);
 246
 247         /*
 248          * Debugging aid: "show_stack(NULL, NULL);" prints the
 249          * back trace for this cpu:
 250          */
 251         if (sp == NULL) {
 252                 if (task)
 253                         sp = (unsigned long *)task->thread.sp;
 254                 else
 255                         sp = (unsigned long *)&sp;
 256         }
 257
 258         stack = sp;
 259         for (i = 0; i < kstack_depth_to_print; i++) {
 260                 if (stack >= irq_stack && stack <= irq_stack_end) {
 261                         if (stack == irq_stack_end) {
 262                                 stack = (unsigned long *) (irq_stack_end[-1]);
 263                                 printk(" <EOI> ");
 264                         }
 265                 } else {
 266                 if (((long) stack & (THREAD_SIZE-1)) == 0)
 267                         break;
 268                 }
 269                 if (i && ((i % STACKSLOTS_PER_LINE) == 0))
 270                         printk("\n%s", log_lvl);
 271                 printk(" %016lx", *stack++);
 272                 touch_nmi_watchdog();
 273         }
 274         preempt_enable();
 275
 276         printk("\n");
 277         show_trace_log_lvl(task, regs, sp, bp, log_lvl);
 278 }
 279
 280 void show_registers(struct pt_regs *regs)
 281 {
 282         int i;
 283         unsigned long sp;
 284         const int cpu = smp_processor_id();
 285         struct task_struct *cur = current;
 286
 287         sp = regs->sp;
 288         printk("CPU %d ", cpu);
 289         print_modules();
 290         __show_regs(regs, 1);
 291         printk("Process %s (pid: %d, threadinfo %p, task %p)\n",
 292                 cur->comm, cur->pid, task_thread_info(cur), cur);
 293
 294         /*
 295          * When in-kernel, we also print out the stack and code at the
 296          * time of the fault..
 297          */
 298         if (!user_mode(regs)) {
 299                 unsigned int code_prologue = code_bytes * 43 / 64;
 300                 unsigned int code_len = code_bytes;
 301                 unsigned char c;
 302                 u8 *ip;
 303
 304                 printk(KERN_EMERG "Stack:\n");
 305                 show_stack_log_lvl(NULL, regs, (unsigned long *)sp,
 306                                 regs->bp, KERN_EMERG);
 307
 308                 printk(KERN_EMERG "Code: ");
 309
 310                 ip = (u8 *)regs->ip - code_prologue;
 311                 if (ip < (u8 *)PAGE_OFFSET || probe_kernel_address(ip, c)) {
 312                         /* try starting at IP */
 313                         ip = (u8 *)regs->ip;
 314                         code_len = code_len - code_prologue + 1;
 315                 }
 316                 for (i = 0; i < code_len; i++, ip++) {
 317                         if (ip < (u8 *)PAGE_OFFSET ||
 318                                         probe_kernel_address(ip, c)) {
 319                                 printk(" Bad RIP value.");
 320                                 break;
 321                         }
 322                         if (ip == (u8 *)regs->ip)
 323                                 printk("<%02x> ", c);
 324                         else
 325                                 printk("%02x ", c);
 326                 }
 327         }
 328         printk("\n");
 329 }
 330
 331 int is_valid_bugaddr(unsigned long ip)
 332 {
 333         unsigned short ud2;
 334
 335         if (__copy_from_user(&ud2, (const void __user *) ip, sizeof(ud2)))
 336                 return 0;
 337
 338         return ud2 == 0x0b0f;
 339 }