arch/arm64/include/asm/stacktrace.h

   1 /* SPDX-License-Identifier: GPL-2.0-only */
   2 /*
   3  * Copyright (C) 2012 ARM Ltd.
   4  */
   5 #ifndef __ASM_STACKTRACE_H
   6 #define __ASM_STACKTRACE_H
   7
   8 #include <linux/percpu.h>
   9 #include <linux/sched.h>
  10 #include <linux/sched/task_stack.h>
  11 #include <linux/types.h>
  12
  13 #include <asm/memory.h>
  14 #include <asm/ptrace.h>
  15 #include <asm/sdei.h>
  16
  17 enum stack_type {
  18         STACK_TYPE_UNKNOWN,
  19         STACK_TYPE_TASK,
  20         STACK_TYPE_IRQ,
  21         STACK_TYPE_OVERFLOW,
  22         STACK_TYPE_SDEI_NORMAL,
  23         STACK_TYPE_SDEI_CRITICAL,
  24         __NR_STACK_TYPES
  25 };
  26
  27 struct stack_info {
  28         unsigned long low;
  29         unsigned long high;
  30         enum stack_type type;
  31 };
  32
  33 /*
  34  * A snapshot of a frame record or fp/lr register values, along with some
  35  * accounting information necessary for robust unwinding.
  36  *
  37  * @fp:          The fp value in the frame record (or the real fp)
  38  * @pc:          The fp value in the frame record (or the real lr)
  39  *
  40  * @stacks_done: Stacks which have been entirely unwound, for which it is no
  41  *               longer valid to unwind to.
  42  *
  43  * @prev_fp:     The fp that pointed to this frame record, or a synthetic value
  44  *               of 0. This is used to ensure that within a stack, each
  45  *               subsequent frame record is at an increasing address.
  46  * @prev_type:   The type of stack this frame record was on, or a synthetic
  47  *               value of STACK_TYPE_UNKNOWN. This is used to detect a
  48  *               transition from one stack to another.
  49  *
  50  * @graph:       When FUNCTION_GRAPH_TRACER is selected, holds the index of a
  51  *               replacement lr value in the ftrace graph stack.
  52  */
  53 struct stackframe {
  54         unsigned long fp;
  55         unsigned long pc;
  56         DECLARE_BITMAP(stacks_done, __NR_STACK_TYPES);
  57         unsigned long prev_fp;
  58         enum stack_type prev_type;
  59 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
  60         int graph;
  61 #endif
  62 };
  63
  64 extern int unwind_frame(struct task_struct *tsk, struct stackframe *frame);
  65 extern void walk_stackframe(struct task_struct *tsk, struct stackframe *frame,
  66                             int (*fn)(struct stackframe *, void *), void *data);
  67 extern void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk);
  68
  69 DECLARE_PER_CPU(unsigned long *, irq_stack_ptr);
  70
  71 static inline bool on_irq_stack(unsigned long sp,
  72                                 struct stack_info *info)
  73 {
  74         unsigned long low = (unsigned long)raw_cpu_read(irq_stack_ptr);
  75         unsigned long high = low + IRQ_STACK_SIZE;
  76
  77         if (!low)
  78                 return false;
  79
  80         if (sp < low || sp >= high)
  81                 return false;
  82
  83         if (info) {
  84                 info->low = low;
  85                 info->high = high;
  86                 info->type = STACK_TYPE_IRQ;
  87         }
  88
  89         return true;
  90 }
  91
  92 static inline bool on_task_stack(const struct task_struct *tsk,
  93                                  unsigned long sp,
  94                                  struct stack_info *info)
  95 {
  96         unsigned long low = (unsigned long)task_stack_page(tsk);
  97         unsigned long high = low + THREAD_SIZE;
  98
  99         if (sp < low || sp >= high)
 100                 return false;
 101
 102         if (info) {
 103                 info->low = low;
 104                 info->high = high;
 105                 info->type = STACK_TYPE_TASK;
 106         }
 107
 108         return true;
 109 }
 110
 111 #ifdef CONFIG_VMAP_STACK
 112 DECLARE_PER_CPU(unsigned long [OVERFLOW_STACK_SIZE/sizeof(long)], overflow_stack);
 113
 114 static inline bool on_overflow_stack(unsigned long sp,
 115                                 struct stack_info *info)
 116 {
 117         unsigned long low = (unsigned long)raw_cpu_ptr(overflow_stack);
 118         unsigned long high = low + OVERFLOW_STACK_SIZE;
 119
 120         if (sp < low || sp >= high)
 121                 return false;
 122
 123         if (info) {
 124                 info->low = low;
 125                 info->high = high;
 126                 info->type = STACK_TYPE_OVERFLOW;
 127         }
 128
 129         return true;
 130 }
 131 #else
 132 static inline bool on_overflow_stack(unsigned long sp,
 133                         struct stack_info *info) { return false; }
 134 #endif
 135
 136
 137 /*
 138  * We can only safely access per-cpu stacks from current in a non-preemptible
 139  * context.
 140  */
 141 static inline bool on_accessible_stack(const struct task_struct *tsk,
 142                                        unsigned long sp,
 143                                        struct stack_info *info)
 144 {
 145         if (info)
 146                 info->type = STACK_TYPE_UNKNOWN;
 147
 148         if (on_task_stack(tsk, sp, info))
 149                 return true;
 150         if (tsk != current || preemptible())
 151                 return false;
 152         if (on_irq_stack(sp, info))
 153                 return true;
 154         if (on_overflow_stack(sp, info))
 155                 return true;
 156         if (on_sdei_stack(sp, info))
 157                 return true;
 158
 159         return false;
 160 }
 161
 162 static inline void start_backtrace(struct stackframe *frame,
 163                                    unsigned long fp, unsigned long pc)
 164 {
 165         frame->fp = fp;
 166         frame->pc = pc;
 167 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 168         frame->graph = 0;
 169 #endif
 170
 171         /*
 172          * Prime the first unwind.
 173          *
 174          * In unwind_frame() we'll check that the FP points to a valid stack,
 175          * which can't be STACK_TYPE_UNKNOWN, and the first unwind will be
 176          * treated as a transition to whichever stack that happens to be. The
 177          * prev_fp value won't be used, but we set it to 0 such that it is
 178          * definitely not an accessible stack address.
 179          */
 180         bitmap_zero(frame->stacks_done, __NR_STACK_TYPES);
 181         frame->prev_fp = 0;
 182         frame->prev_type = STACK_TYPE_UNKNOWN;
 183 }
 184
 185 #endif  /* __ASM_STACKTRACE_H */