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_ENTRY) {
  41                 /*
  42                  * On 64-bit, we have a generic entry stack that we
  43                  * use for all the kernel entry points, including
  44                  * SYSENTER.
  45                  */
  46                 return "ENTRY_TRAMPOLINE";
  47         }
  48
  49         if (type >= STACK_TYPE_EXCEPTION && type <= STACK_TYPE_EXCEPTION_LAST)
  50                 return exception_stack_names[type - STACK_TYPE_EXCEPTION];
  51
  52         return NULL;
  53 }
  54
  55 static bool in_exception_stack(unsigned long *stack, struct stack_info *info)
  56 {
  57         unsigned long *begin, *end;
  58         struct pt_regs *regs;
  59         unsigned k;
  60
  61         BUILD_BUG_ON(N_EXCEPTION_STACKS != 4);
  62
  63         for (k = 0; k < N_EXCEPTION_STACKS; k++) {
  64                 end   = (unsigned long *)raw_cpu_ptr(&orig_ist)->ist[k];
  65                 begin = end - (exception_stack_sizes[k] / sizeof(long));
  66                 regs  = (struct pt_regs *)end - 1;
  67
  68                 if (stack <= begin || stack >= end)
  69                         continue;
  70
  71                 info->type      = STACK_TYPE_EXCEPTION + k;
  72                 info->begin     = begin;
  73                 info->end       = end;
  74                 info->next_sp   = (unsigned long *)regs->sp;
  75
  76                 return true;
  77         }
  78
  79         return false;
  80 }
  81
  82 static bool in_irq_stack(unsigned long *stack, struct stack_info *info)
  83 {
  84         unsigned long *end   = (unsigned long *)this_cpu_read(irq_stack_ptr);
  85         unsigned long *begin = end - (IRQ_STACK_SIZE / sizeof(long));
  86
  87         /*
  88          * This is a software stack, so 'end' can be a valid stack pointer.
  89          * It just means the stack is empty.
  90          */
  91         if (stack <= begin || stack > end)
  92                 return false;
  93
  94         info->type      = STACK_TYPE_IRQ;
  95         info->begin     = begin;
  96         info->end       = end;
  97
  98         /*
  99          * The next stack pointer is the first thing pushed by the entry code
 100          * after switching to the irq stack.
 101          */
 102         info->next_sp = (unsigned long *)*(end - 1);
 103
 104         return true;
 105 }
 106
 107 int get_stack_info(unsigned long *stack, struct task_struct *task,
 108                    struct stack_info *info, unsigned long *visit_mask)
 109 {
 110         if (!stack)
 111                 goto unknown;
 112
 113         task = task ? : current;
 114
 115         if (in_task_stack(stack, task, info))
 116                 goto recursion_check;
 117
 118         if (task != current)
 119                 goto unknown;
 120
 121         if (in_exception_stack(stack, info))
 122                 goto recursion_check;
 123
 124         if (in_irq_stack(stack, info))
 125                 goto recursion_check;
 126
 127         if (in_entry_stack(stack, info))
 128                 goto recursion_check;
 129
 130         goto unknown;
 131
 132 recursion_check:
 133         /*
 134          * Make sure we don't iterate through any given stack more than once.
 135          * If it comes up a second time then there's something wrong going on:
 136          * just break out and report an unknown stack type.
 137          */
 138         if (visit_mask) {
 139                 if (*visit_mask & (1UL << info->type)) {
 140                         printk_deferred_once(KERN_WARNING "WARNING: stack recursion on stack type %d\n", info->type);
 141                         goto unknown;
 142                 }
 143                 *visit_mask |= 1UL << info->type;
 144         }
 145
 146         return 0;
 147
 148 unknown:
 149         info->type = STACK_TYPE_UNKNOWN;
 150         return -EINVAL;
 151 }