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 #ifdef CONFIG_FRAME_POINTER 16 17 struct stackframe { 18 unsigned long fp; 19 unsigned long ra; 20 }; 21 22 static void notrace walk_stackframe(struct task_struct *task, 23 struct pt_regs *regs, bool (*fn)(unsigned long, void *), void *arg) 24 { 25 unsigned long fp, sp, pc; 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 const register unsigned long current_sp __asm__ ("sp"); 33 fp = (unsigned long)__builtin_frame_address(0); 34 sp = current_sp; 35 pc = (unsigned long)walk_stackframe; 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) || fn(pc, arg))) 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 fp = frame->fp; 59 pc = ftrace_graph_ret_addr(current, NULL, frame->ra, 60 (unsigned long *)(fp - 8)); 61 } 62 } 63 64 #else /* !CONFIG_FRAME_POINTER */ 65 66 static void notrace walk_stackframe(struct task_struct *task, 67 struct pt_regs *regs, bool (*fn)(unsigned long, void *), void *arg) 68 { 69 unsigned long sp, pc; 70 unsigned long *ksp; 71 72 if (regs) { 73 sp = user_stack_pointer(regs); 74 pc = instruction_pointer(regs); 75 } else if (task == NULL || task == current) { 76 const register unsigned long current_sp __asm__ ("sp"); 77 sp = current_sp; 78 pc = (unsigned long)walk_stackframe; 79 } else { 80 /* task blocked in __switch_to */ 81 sp = task->thread.sp; 82 pc = task->thread.ra; 83 } 84 85 if (unlikely(sp & 0x7)) 86 return; 87 88 ksp = (unsigned long *)sp; 89 while (!kstack_end(ksp)) { 90 if (__kernel_text_address(pc) && unlikely(fn(pc, arg))) 91 break; 92 pc = (*ksp++) - 0x4; 93 } 94 } 95 96 #endif /* CONFIG_FRAME_POINTER */ 97 98 99 static bool print_trace_address(unsigned long pc, void *arg) 100 { 101 print_ip_sym(pc); 102 return false; 103 } 104 105 void show_stack(struct task_struct *task, unsigned long *sp) 106 { 107 pr_cont("Call Trace:\n"); 108 walk_stackframe(task, NULL, print_trace_address, NULL); 109 } 110 111 112 static bool save_wchan(unsigned long pc, void *arg) 113 { 114 if (!in_sched_functions(pc)) { 115 unsigned long *p = arg; 116 *p = pc; 117 return true; 118 } 119 return false; 120 } 121 122 unsigned long get_wchan(struct task_struct *task) 123 { 124 unsigned long pc = 0; 125 126 if (likely(task && task != current && task->state != TASK_RUNNING)) 127 walk_stackframe(task, NULL, save_wchan, &pc); 128 return pc; 129 } 130 131 132 #ifdef CONFIG_STACKTRACE 133 134 static bool __save_trace(unsigned long pc, void *arg, bool nosched) 135 { 136 struct stack_trace *trace = arg; 137 138 if (unlikely(nosched && in_sched_functions(pc))) 139 return false; 140 if (unlikely(trace->skip > 0)) { 141 trace->skip--; 142 return false; 143 } 144 145 trace->entries[trace->nr_entries++] = pc; 146 return (trace->nr_entries >= trace->max_entries); 147 } 148 149 static bool save_trace(unsigned long pc, void *arg) 150 { 151 return __save_trace(pc, arg, false); 152 } 153 154 /* 155 * Save stack-backtrace addresses into a stack_trace buffer. 156 */ 157 void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace) 158 { 159 walk_stackframe(tsk, NULL, save_trace, trace); 160 } 161 EXPORT_SYMBOL_GPL(save_stack_trace_tsk); 162 163 void save_stack_trace(struct stack_trace *trace) 164 { 165 save_stack_trace_tsk(NULL, trace); 166 } 167 EXPORT_SYMBOL_GPL(save_stack_trace); 168 169 #endif /* CONFIG_STACKTRACE */ 170