arch/x86/kernel/dumpstack_64.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  *  Copyright (C) 1991, 1992  Linus Torvalds
   4  *  Copyright (C) 2000, 2001, 2002 Andi Kleen, SuSE Labs
   5  */
   6 #include <linux/sched/debug.h>
   7 #include <linux/kallsyms.h>
   8 #include <linux/kprobes.h>
   9 #include <linux/uaccess.h>
  10 #include <linux/hardirq.h>
  11 #include <linux/kdebug.h>
  12 #include <linux/export.h>
  13 #include <linux/ptrace.h>
  14 #include <linux/kexec.h>
  15 #include <linux/sysfs.h>
  16 #include <linux/bug.h>
  17 #include <linux/nmi.h>
  18
  19 #include <asm/stacktrace.h>
  20
  21 static char *exception_stack_names[N_EXCEPTION_STACKS] = {
  22                 [ DOUBLEFAULT_STACK-1   ]       = "#DF",
  23                 [ NMI_STACK-1           ]       = "NMI",
  24                 [ DEBUG_STACK-1         ]       = "#DB",
  25                 [ MCE_STACK-1           ]       = "#MC",
  26 };
  27
  28 static unsigned long exception_stack_sizes[N_EXCEPTION_STACKS] = {
  29         [0 ... N_EXCEPTION_STACKS - 1]          = EXCEPTION_STKSZ,
  30         [DEBUG_STACK - 1]                       = DEBUG_STKSZ
  31 };
  32
  33 const char *stack_type_name(enum stack_type type)
  34 {
  35         BUILD_BUG_ON(N_EXCEPTION_STACKS != 4);
  36
  37         if (type == STACK_TYPE_IRQ)
  38                 return "IRQ";
  39
  40         if (type >= STACK_TYPE_EXCEPTION && type <= STACK_TYPE_EXCEPTION_LAST)
  41                 return exception_stack_names[type - STACK_TYPE_EXCEPTION];
  42
  43         return NULL;
  44 }
  45
  46 static bool in_exception_stack(unsigned long *stack, struct stack_info *info)
  47 {
  48         unsigned long *begin, *end;
  49         struct pt_regs *regs;
  50         unsigned k;
  51
  52         BUILD_BUG_ON(N_EXCEPTION_STACKS != 4);
  53
  54         for (k = 0; k < N_EXCEPTION_STACKS; k++) {
  55                 end   = (unsigned long *)raw_cpu_ptr(&orig_ist)->ist[k];
  56                 begin = end - (exception_stack_sizes[k] / sizeof(long));
  57                 regs  = (struct pt_regs *)end - 1;
  58
  59                 if (stack <= begin || stack >= end)
  60                         continue;
  61
  62                 info->type      = STACK_TYPE_EXCEPTION + k;
  63                 info->begin     = begin;
  64                 info->end       = end;
  65                 info->next_sp   = (unsigned long *)regs->sp;
  66
  67                 return true;
  68         }
  69
  70         return false;
  71 }
  72
  73 static bool in_irq_stack(unsigned long *stack, struct stack_info *info)
  74 {
  75         unsigned long *end   = (unsigned long *)this_cpu_read(irq_stack_ptr);
  76         unsigned long *begin = end - (IRQ_STACK_SIZE / sizeof(long));
  77
  78         /*
  79          * This is a software stack, so 'end' can be a valid stack pointer.
  80          * It just means the stack is empty.
  81          */
  82         if (stack <= begin || stack > end)
  83                 return false;
  84
  85         info->type      = STACK_TYPE_IRQ;
  86         info->begin     = begin;
  87         info->end       = end;
  88
  89         /*
  90          * The next stack pointer is the first thing pushed by the entry code
  91          * after switching to the irq stack.
  92          */
  93         info->next_sp = (unsigned long *)*(end - 1);
  94
  95         return true;
  96 }
  97
  98 int get_stack_info(unsigned long *stack, struct task_struct *task,
  99                    struct stack_info *info, unsigned long *visit_mask)
 100 {
 101         if (!stack)
 102                 goto unknown;
 103
 104         task = task ? : current;
 105
 106         if (in_task_stack(stack, task, info))
 107                 goto recursion_check;
 108
 109         if (task != current)
 110                 goto unknown;
 111
 112         if (in_exception_stack(stack, info))
 113                 goto recursion_check;
 114
 115         if (in_irq_stack(stack, info))
 116                 goto recursion_check;
 117
 118         goto unknown;
 119
 120 recursion_check:
 121         /*
 122          * Make sure we don't iterate through any given stack more than once.
 123          * If it comes up a second time then there's something wrong going on:
 124          * just break out and report an unknown stack type.
 125          */
 126         if (visit_mask) {
 127                 if (*visit_mask & (1UL << info->type)) {
 128                         printk_deferred_once(KERN_WARNING "WARNING: stack recursion on stack type %d\n", info->type);
 129                         goto unknown;
 130                 }
 131                 *visit_mask |= 1UL << info->type;
 132         }
 133
 134         return 0;
 135
 136 unknown:
 137         info->type = STACK_TYPE_UNKNOWN;
 138         return -EINVAL;
 139 }
 140
 141 void show_regs(struct pt_regs *regs)
 142 {
 143         int i;
 144
 145         show_regs_print_info(KERN_DEFAULT);
 146         __show_regs(regs, 1);
 147
 148         /*
 149          * When in-kernel, we also print out the stack and code at the
 150          * time of the fault..
 151          */
 152         if (!user_mode(regs)) {
 153                 unsigned int code_prologue = code_bytes * 43 / 64;
 154                 unsigned int code_len = code_bytes;
 155                 unsigned char c;
 156                 u8 *ip;
 157
 158                 show_trace_log_lvl(current, regs, NULL, KERN_DEFAULT);
 159
 160                 printk(KERN_DEFAULT "Code: ");
 161
 162                 ip = (u8 *)regs->ip - code_prologue;
 163                 if (ip < (u8 *)PAGE_OFFSET || probe_kernel_address(ip, c)) {
 164                         /* try starting at IP */
 165                         ip = (u8 *)regs->ip;
 166                         code_len = code_len - code_prologue + 1;
 167                 }
 168                 for (i = 0; i < code_len; i++, ip++) {
 169                         if (ip < (u8 *)PAGE_OFFSET ||
 170                                         probe_kernel_address(ip, c)) {
 171                                 pr_cont(" Bad RIP value.");
 172                                 break;
 173                         }
 174                         if (ip == (u8 *)regs->ip)
 175                                 pr_cont("<%02x> ", c);
 176                         else
 177                                 pr_cont("%02x ", c);
 178                 }
 179         }
 180         pr_cont("\n");
 181 }