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