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 void notrace walk_stackframe(struct task_struct *task, struct pt_regs *regs, 20 bool (*fn)(void *, unsigned long), void *arg) 21 { 22 unsigned long fp, sp, pc; 23 int level = 0; 24 25 if (regs) { 26 fp = frame_pointer(regs); 27 sp = user_stack_pointer(regs); 28 pc = instruction_pointer(regs); 29 } else if (task == NULL || task == current) { 30 fp = (unsigned long)__builtin_frame_address(0); 31 sp = current_stack_pointer; 32 pc = (unsigned long)walk_stackframe; 33 } else { 34 /* task blocked in __switch_to */ 35 fp = task->thread.s[0]; 36 sp = task->thread.sp; 37 pc = task->thread.ra; 38 } 39 40 for (;;) { 41 unsigned long low, high; 42 struct stackframe *frame; 43 44 if (unlikely(!__kernel_text_address(pc) || (level++ >= 1 && !fn(arg, pc)))) 45 break; 46 47 /* Validate frame pointer */ 48 low = sp + sizeof(struct stackframe); 49 high = ALIGN(sp, THREAD_SIZE); 50 if (unlikely(fp < low || fp > high || fp & 0x7)) 51 break; 52 /* Unwind stack frame */ 53 frame = (struct stackframe *)fp - 1; 54 sp = fp; 55 if (regs && (regs->epc == pc) && (frame->fp & 0x7)) { 56 fp = frame->ra; 57 pc = regs->ra; 58 } else { 59 fp = frame->fp; 60 pc = ftrace_graph_ret_addr(current, NULL, frame->ra, 61 (unsigned long *)(fp - 8)); 62 } 63 64 } 65 } 66 67 #else /* !CONFIG_FRAME_POINTER */ 68 69 void notrace walk_stackframe(struct task_struct *task, 70 struct pt_regs *regs, bool (*fn)(void *, unsigned long), void *arg) 71 { 72 unsigned long sp, pc; 73 unsigned long *ksp; 74 75 if (regs) { 76 sp = user_stack_pointer(regs); 77 pc = instruction_pointer(regs); 78 } else if (task == NULL || task == current) { 79 sp = current_stack_pointer; 80 pc = (unsigned long)walk_stackframe; 81 } else { 82 /* task blocked in __switch_to */ 83 sp = task->thread.sp; 84 pc = task->thread.ra; 85 } 86 87 if (unlikely(sp & 0x7)) 88 return; 89 90 ksp = (unsigned long *)sp; 91 while (!kstack_end(ksp)) { 92 if (__kernel_text_address(pc) && unlikely(!fn(arg, pc))) 93 break; 94 pc = (*ksp++) - 0x4; 95 } 96 } 97 98 #endif /* CONFIG_FRAME_POINTER */ 99 100 static bool print_trace_address(void *arg, unsigned long pc) 101 { 102 const char *loglvl = arg; 103 104 print_ip_sym(loglvl, pc); 105 return true; 106 } 107 108 noinline void dump_backtrace(struct pt_regs *regs, struct task_struct *task, 109 const char *loglvl) 110 { 111 walk_stackframe(task, regs, print_trace_address, (void *)loglvl); 112 } 113 114 void show_stack(struct task_struct *task, unsigned long *sp, const char *loglvl) 115 { 116 pr_cont("%sCall Trace:\n", loglvl); 117 dump_backtrace(NULL, task, loglvl); 118 } 119 120 static bool save_wchan(void *arg, unsigned long pc) 121 { 122 if (!in_sched_functions(pc)) { 123 unsigned long *p = arg; 124 *p = pc; 125 return false; 126 } 127 return true; 128 } 129 130 unsigned long __get_wchan(struct task_struct *task) 131 { 132 unsigned long pc = 0; 133 134 if (!try_get_task_stack(task)) 135 return 0; 136 walk_stackframe(task, NULL, save_wchan, &pc); 137 put_task_stack(task); 138 return pc; 139 } 140 141 noinline void arch_stack_walk(stack_trace_consume_fn consume_entry, void *cookie, 142 struct task_struct *task, struct pt_regs *regs) 143 { 144 walk_stackframe(task, regs, consume_entry, cookie); 145 } 146