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 const char *loglvl); 69 70 DECLARE_PER_CPU(unsigned long *, irq_stack_ptr); 71 72 static inline bool on_stack(unsigned long sp, unsigned long low, 73 unsigned long high, enum stack_type type, 74 struct stack_info *info) 75 { 76 if (!low) 77 return false; 78 79 if (sp < low || sp >= high) 80 return false; 81 82 if (info) { 83 info->low = low; 84 info->high = high; 85 info->type = type; 86 } 87 return true; 88 } 89 90 static inline bool on_irq_stack(unsigned long sp, 91 struct stack_info *info) 92 { 93 unsigned long low = (unsigned long)raw_cpu_read(irq_stack_ptr); 94 unsigned long high = low + IRQ_STACK_SIZE; 95 96 return on_stack(sp, low, high, STACK_TYPE_IRQ, info); 97 } 98 99 static inline bool on_task_stack(const struct task_struct *tsk, 100 unsigned long sp, 101 struct stack_info *info) 102 { 103 unsigned long low = (unsigned long)task_stack_page(tsk); 104 unsigned long high = low + THREAD_SIZE; 105 106 return on_stack(sp, low, high, STACK_TYPE_TASK, info); 107 } 108 109 #ifdef CONFIG_VMAP_STACK 110 DECLARE_PER_CPU(unsigned long [OVERFLOW_STACK_SIZE/sizeof(long)], overflow_stack); 111 112 static inline bool on_overflow_stack(unsigned long sp, 113 struct stack_info *info) 114 { 115 unsigned long low = (unsigned long)raw_cpu_ptr(overflow_stack); 116 unsigned long high = low + OVERFLOW_STACK_SIZE; 117 118 return on_stack(sp, low, high, STACK_TYPE_OVERFLOW, info); 119 } 120 #else 121 static inline bool on_overflow_stack(unsigned long sp, 122 struct stack_info *info) { return false; } 123 #endif 124 125 126 /* 127 * We can only safely access per-cpu stacks from current in a non-preemptible 128 * context. 129 */ 130 static inline bool on_accessible_stack(const struct task_struct *tsk, 131 unsigned long sp, 132 struct stack_info *info) 133 { 134 if (info) 135 info->type = STACK_TYPE_UNKNOWN; 136 137 if (on_task_stack(tsk, sp, info)) 138 return true; 139 if (tsk != current || preemptible()) 140 return false; 141 if (on_irq_stack(sp, info)) 142 return true; 143 if (on_overflow_stack(sp, info)) 144 return true; 145 if (on_sdei_stack(sp, info)) 146 return true; 147 148 return false; 149 } 150 151 static inline void start_backtrace(struct stackframe *frame, 152 unsigned long fp, unsigned long pc) 153 { 154 frame->fp = fp; 155 frame->pc = pc; 156 #ifdef CONFIG_FUNCTION_GRAPH_TRACER 157 frame->graph = 0; 158 #endif 159 160 /* 161 * Prime the first unwind. 162 * 163 * In unwind_frame() we'll check that the FP points to a valid stack, 164 * which can't be STACK_TYPE_UNKNOWN, and the first unwind will be 165 * treated as a transition to whichever stack that happens to be. The 166 * prev_fp value won't be used, but we set it to 0 such that it is 167 * definitely not an accessible stack address. 168 */ 169 bitmap_zero(frame->stacks_done, __NR_STACK_TYPES); 170 frame->prev_fp = 0; 171 frame->prev_type = STACK_TYPE_UNKNOWN; 172 } 173 174 #endif /* __ASM_STACKTRACE_H */ 175