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/cpu_entry_area.h>
  20 #include <asm/stacktrace.h>
  21
  22 static const char * const exception_stack_names[] = {
  23                 [ ESTACK_DF     ]       = "#DF",
  24                 [ ESTACK_NMI    ]       = "NMI",
  25                 [ ESTACK_DB     ]       = "#DB",
  26                 [ ESTACK_MCE    ]       = "#MC",
  27                 [ ESTACK_VC     ]       = "#VC",
  28                 [ ESTACK_VC2    ]       = "#VC2",
  29 };
  30
  31 const char *stack_type_name(enum stack_type type)
  32 {
  33         BUILD_BUG_ON(N_EXCEPTION_STACKS != 6);
  34
  35         if (type == STACK_TYPE_TASK)
  36                 return "TASK";
  37
  38         if (type == STACK_TYPE_IRQ)
  39                 return "IRQ";
  40
  41         if (type == STACK_TYPE_SOFTIRQ)
  42                 return "SOFTIRQ";
  43
  44         if (type == STACK_TYPE_ENTRY) {
  45                 /*
  46                  * On 64-bit, we have a generic entry stack that we
  47                  * use for all the kernel entry points, including
  48                  * SYSENTER.
  49                  */
  50                 return "ENTRY_TRAMPOLINE";
  51         }
  52
  53         if (type >= STACK_TYPE_EXCEPTION && type <= STACK_TYPE_EXCEPTION_LAST)
  54                 return exception_stack_names[type - STACK_TYPE_EXCEPTION];
  55
  56         return NULL;
  57 }
  58
  59 /**
  60  * struct estack_pages - Page descriptor for exception stacks
  61  * @offs:       Offset from the start of the exception stack area
  62  * @size:       Size of the exception stack
  63  * @type:       Type to store in the stack_info struct
  64  */
  65 struct estack_pages {
  66         u32     offs;
  67         u16     size;
  68         u16     type;
  69 };
  70
  71 #define EPAGERANGE(st)                                                  \
  72         [PFN_DOWN(CEA_ESTACK_OFFS(st)) ...                              \
  73          PFN_DOWN(CEA_ESTACK_OFFS(st) + CEA_ESTACK_SIZE(st) - 1)] = {   \
  74                 .offs   = CEA_ESTACK_OFFS(st),                          \
  75                 .size   = CEA_ESTACK_SIZE(st),                          \
  76                 .type   = STACK_TYPE_EXCEPTION + ESTACK_ ##st, }
  77
  78 /*
  79  * Array of exception stack page descriptors. If the stack is larger than
  80  * PAGE_SIZE, all pages covering a particular stack will have the same
  81  * info. The guard pages including the not mapped DB2 stack are zeroed
  82  * out.
  83  */
  84 static const
  85 struct estack_pages estack_pages[CEA_ESTACK_PAGES] ____cacheline_aligned = {
  86         EPAGERANGE(DF),
  87         EPAGERANGE(NMI),
  88         EPAGERANGE(DB),
  89         EPAGERANGE(MCE),
  90         EPAGERANGE(VC),
  91         EPAGERANGE(VC2),
  92 };
  93
  94 static __always_inline bool in_exception_stack(unsigned long *stack, struct stack_info *info)
  95 {
  96         unsigned long begin, end, stk = (unsigned long)stack;
  97         const struct estack_pages *ep;
  98         struct pt_regs *regs;
  99         unsigned int k;
 100
 101         BUILD_BUG_ON(N_EXCEPTION_STACKS != 6);
 102
 103         begin = (unsigned long)__this_cpu_read(cea_exception_stacks);
 104         /*
 105          * Handle the case where stack trace is collected _before_
 106          * cea_exception_stacks had been initialized.
 107          */
 108         if (!begin)
 109                 return false;
 110
 111         end = begin + sizeof(struct cea_exception_stacks);
 112         /* Bail if @stack is outside the exception stack area. */
 113         if (stk < begin || stk >= end)
 114                 return false;
 115
 116         /* Calc page offset from start of exception stacks */
 117         k = (stk - begin) >> PAGE_SHIFT;
 118         /* Lookup the page descriptor */
 119         ep = &estack_pages[k];
 120         /* Guard page? */
 121         if (!ep->size)
 122                 return false;
 123
 124         begin += (unsigned long)ep->offs;
 125         end = begin + (unsigned long)ep->size;
 126         regs = (struct pt_regs *)end - 1;
 127
 128         info->type      = ep->type;
 129         info->begin     = (unsigned long *)begin;
 130         info->end       = (unsigned long *)end;
 131         info->next_sp   = (unsigned long *)regs->sp;
 132         return true;
 133 }
 134
 135 static __always_inline bool in_irq_stack(unsigned long *stack, struct stack_info *info)
 136 {
 137         unsigned long *end = (unsigned long *)this_cpu_read(pcpu_hot.hardirq_stack_ptr);
 138         unsigned long *begin;
 139
 140         /*
 141          * @end points directly to the top most stack entry to avoid a -8
 142          * adjustment in the stack switch hotpath. Adjust it back before
 143          * calculating @begin.
 144          */
 145         end++;
 146         begin = end - (IRQ_STACK_SIZE / sizeof(long));
 147
 148         /*
 149          * Due to the switching logic RSP can never be == @end because the
 150          * final operation is 'popq %rsp' which means after that RSP points
 151          * to the original stack and not to @end.
 152          */
 153         if (stack < begin || stack >= end)
 154                 return false;
 155
 156         info->type      = STACK_TYPE_IRQ;
 157         info->begin     = begin;
 158         info->end       = end;
 159
 160         /*
 161          * The next stack pointer is stored at the top of the irq stack
 162          * before switching to the irq stack. Actual stack entries are all
 163          * below that.
 164          */
 165         info->next_sp = (unsigned long *)*(end - 1);
 166
 167         return true;
 168 }
 169
 170 bool noinstr get_stack_info_noinstr(unsigned long *stack, struct task_struct *task,
 171                                     struct stack_info *info)
 172 {
 173         if (in_task_stack(stack, task, info))
 174                 return true;
 175
 176         if (task != current)
 177                 return false;
 178
 179         if (in_exception_stack(stack, info))
 180                 return true;
 181
 182         if (in_irq_stack(stack, info))
 183                 return true;
 184
 185         if (in_entry_stack(stack, info))
 186                 return true;
 187
 188         return false;
 189 }
 190
 191 int get_stack_info(unsigned long *stack, struct task_struct *task,
 192                    struct stack_info *info, unsigned long *visit_mask)
 193 {
 194         task = task ? : current;
 195
 196         if (!stack)
 197                 goto unknown;
 198
 199         if (!get_stack_info_noinstr(stack, task, info))
 200                 goto unknown;
 201
 202         /*
 203          * Make sure we don't iterate through any given stack more than once.
 204          * If it comes up a second time then there's something wrong going on:
 205          * just break out and report an unknown stack type.
 206          */
 207         if (visit_mask) {
 208                 if (*visit_mask & (1UL << info->type)) {
 209                         if (task == current)
 210                                 printk_deferred_once(KERN_WARNING "WARNING: stack recursion on stack type %d\n", info->type);
 211                         goto unknown;
 212                 }
 213                 *visit_mask |= 1UL << info->type;
 214         }
 215
 216         return 0;
 217
 218 unknown:
 219         info->type = STACK_TYPE_UNKNOWN;
 220         return -EINVAL;
 221 }