1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Copyright (C) 2008 ARM Limited 4 * Copyright (C) 2014 Regents of the University of California 5 */ 6 7 #include <linux/export.h> 8 #include <linux/kallsyms.h> 9 #include <linux/sched.h> 10 #include <linux/sched/debug.h> 11 #include <linux/sched/task_stack.h> 12 #include <linux/stacktrace.h> 13 #include <linux/ftrace.h> 14 15 #include <asm/stacktrace.h> 16 17 #ifdef CONFIG_FRAME_POINTER 18 19 extern asmlinkage void ret_from_exception(void); 20 21 void notrace walk_stackframe(struct task_struct *task, struct pt_regs *regs, 22 bool (*fn)(void *, unsigned long), void *arg) 23 { 24 unsigned long fp, sp, pc; 25 int level = 0; 26 27 if (regs) { 28 fp = frame_pointer(regs); 29 sp = user_stack_pointer(regs); 30 pc = instruction_pointer(regs); 31 } else if (task == NULL || task == current) { 32 fp = (unsigned long)__builtin_frame_address(0); 33 sp = current_stack_pointer; 34 pc = (unsigned long)walk_stackframe; 35 level = -1; 36 } else { 37 /* task blocked in __switch_to */ 38 fp = task->thread.s[0]; 39 sp = task->thread.sp; 40 pc = task->thread.ra; 41 } 42 43 for (;;) { 44 unsigned long low, high; 45 struct stackframe *frame; 46 47 if (unlikely(!__kernel_text_address(pc) || (level++ >= 0 && !fn(arg, pc)))) 48 break; 49 50 /* Validate frame pointer */ 51 low = sp + sizeof(struct stackframe); 52 high = ALIGN(sp, THREAD_SIZE); 53 if (unlikely(fp < low || fp > high || fp & 0x7)) 54 break; 55 /* Unwind stack frame */ 56 frame = (struct stackframe *)fp - 1; 57 sp = fp; 58 if (regs && (regs->epc == pc) && (frame->fp & 0x7)) { 59 fp = frame->ra; 60 pc = regs->ra; 61 } else { 62 fp = frame->fp; 63 pc = ftrace_graph_ret_addr(current, NULL, frame->ra, 64 &frame->ra); 65 if (pc == (unsigned long)ret_from_exception) { 66 if (unlikely(!__kernel_text_address(pc) || !fn(arg, pc))) 67 break; 68 69 pc = ((struct pt_regs *)sp)->epc; 70 fp = ((struct pt_regs *)sp)->s0; 71 } 72 } 73 74 } 75 } 76 77 #else /* !CONFIG_FRAME_POINTER */ 78 79 void notrace walk_stackframe(struct task_struct *task, 80 struct pt_regs *regs, bool (*fn)(void *, unsigned long), void *arg) 81 { 82 unsigned long sp, pc; 83 unsigned long *ksp; 84 85 if (regs) { 86 sp = user_stack_pointer(regs); 87 pc = instruction_pointer(regs); 88 } else if (task == NULL || task == current) { 89 sp = current_stack_pointer; 90 pc = (unsigned long)walk_stackframe; 91 } else { 92 /* task blocked in __switch_to */ 93 sp = task->thread.sp; 94 pc = task->thread.ra; 95 } 96 97 if (unlikely(sp & 0x7)) 98 return; 99 100 ksp = (unsigned long *)sp; 101 while (!kstack_end(ksp)) { 102 if (__kernel_text_address(pc) && unlikely(!fn(arg, pc))) 103 break; 104 pc = READ_ONCE_NOCHECK(*ksp++) - 0x4; 105 } 106 } 107 108 #endif /* CONFIG_FRAME_POINTER */ 109 110 static bool print_trace_address(void *arg, unsigned long pc) 111 { 112 const char *loglvl = arg; 113 114 print_ip_sym(loglvl, pc); 115 return true; 116 } 117 118 noinline void dump_backtrace(struct pt_regs *regs, struct task_struct *task, 119 const char *loglvl) 120 { 121 walk_stackframe(task, regs, print_trace_address, (void *)loglvl); 122 } 123 124 void show_stack(struct task_struct *task, unsigned long *sp, const char *loglvl) 125 { 126 pr_cont("%sCall Trace:\n", loglvl); 127 dump_backtrace(NULL, task, loglvl); 128 } 129 130 static bool save_wchan(void *arg, unsigned long pc) 131 { 132 if (!in_sched_functions(pc)) { 133 unsigned long *p = arg; 134 *p = pc; 135 return false; 136 } 137 return true; 138 } 139 140 unsigned long __get_wchan(struct task_struct *task) 141 { 142 unsigned long pc = 0; 143 144 if (!try_get_task_stack(task)) 145 return 0; 146 walk_stackframe(task, NULL, save_wchan, &pc); 147 put_task_stack(task); 148 return pc; 149 } 150 151 noinline void arch_stack_walk(stack_trace_consume_fn consume_entry, void *cookie, 152 struct task_struct *task, struct pt_regs *regs) 153 { 154 walk_stackframe(task, regs, consume_entry, cookie); 155 } 156