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 register unsigned long sp_in_global __asm__("sp"); 23 24 void notrace walk_stackframe(struct task_struct *task, struct pt_regs *regs, 25 bool (*fn)(unsigned long, void *), void *arg) 26 { 27 unsigned long fp, sp, pc; 28 29 if (regs) { 30 fp = frame_pointer(regs); 31 sp = user_stack_pointer(regs); 32 pc = instruction_pointer(regs); 33 } else if (task == NULL || task == current) { 34 const register unsigned long current_sp = sp_in_global; 35 fp = (unsigned long)__builtin_frame_address(0); 36 sp = current_sp; 37 pc = (unsigned long)walk_stackframe; 38 } else { 39 /* task blocked in __switch_to */ 40 fp = task->thread.s[0]; 41 sp = task->thread.sp; 42 pc = task->thread.ra; 43 } 44 45 for (;;) { 46 unsigned long low, high; 47 struct stackframe *frame; 48 49 if (unlikely(!__kernel_text_address(pc) || fn(pc, arg))) 50 break; 51 52 /* Validate frame pointer */ 53 low = sp + sizeof(struct stackframe); 54 high = ALIGN(sp, THREAD_SIZE); 55 if (unlikely(fp < low || fp > high || fp & 0x7)) 56 break; 57 /* Unwind stack frame */ 58 frame = (struct stackframe *)fp - 1; 59 sp = fp; 60 fp = frame->fp; 61 pc = ftrace_graph_ret_addr(current, NULL, frame->ra, 62 (unsigned long *)(fp - 8)); 63 } 64 } 65 66 #else /* !CONFIG_FRAME_POINTER */ 67 68 static void notrace walk_stackframe(struct task_struct *task, 69 struct pt_regs *regs, bool (*fn)(unsigned long, void *), void *arg) 70 { 71 unsigned long sp, pc; 72 unsigned long *ksp; 73 74 if (regs) { 75 sp = user_stack_pointer(regs); 76 pc = instruction_pointer(regs); 77 } else if (task == NULL || task == current) { 78 sp = sp_in_global; 79 pc = (unsigned long)walk_stackframe; 80 } else { 81 /* task blocked in __switch_to */ 82 sp = task->thread.sp; 83 pc = task->thread.ra; 84 } 85 86 if (unlikely(sp & 0x7)) 87 return; 88 89 ksp = (unsigned long *)sp; 90 while (!kstack_end(ksp)) { 91 if (__kernel_text_address(pc) && unlikely(fn(pc, arg))) 92 break; 93 pc = (*ksp++) - 0x4; 94 } 95 } 96 97 #endif /* CONFIG_FRAME_POINTER */ 98 99 100 static bool print_trace_address(unsigned long pc, void *arg) 101 { 102 print_ip_sym(pc); 103 return false; 104 } 105 106 void show_stack(struct task_struct *task, unsigned long *sp) 107 { 108 pr_cont("Call Trace:\n"); 109 walk_stackframe(task, NULL, print_trace_address, NULL); 110 } 111 112 113 static bool save_wchan(unsigned long pc, void *arg) 114 { 115 if (!in_sched_functions(pc)) { 116 unsigned long *p = arg; 117 *p = pc; 118 return true; 119 } 120 return false; 121 } 122 123 unsigned long get_wchan(struct task_struct *task) 124 { 125 unsigned long pc = 0; 126 127 if (likely(task && task != current && task->state != TASK_RUNNING)) 128 walk_stackframe(task, NULL, save_wchan, &pc); 129 return pc; 130 } 131 132 133 #ifdef CONFIG_STACKTRACE 134 135 static bool __save_trace(unsigned long pc, void *arg, bool nosched) 136 { 137 struct stack_trace *trace = arg; 138 139 if (unlikely(nosched && in_sched_functions(pc))) 140 return false; 141 if (unlikely(trace->skip > 0)) { 142 trace->skip--; 143 return false; 144 } 145 146 trace->entries[trace->nr_entries++] = pc; 147 return (trace->nr_entries >= trace->max_entries); 148 } 149 150 static bool save_trace(unsigned long pc, void *arg) 151 { 152 return __save_trace(pc, arg, false); 153 } 154 155 /* 156 * Save stack-backtrace addresses into a stack_trace buffer. 157 */ 158 void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace) 159 { 160 walk_stackframe(tsk, NULL, save_trace, trace); 161 } 162 EXPORT_SYMBOL_GPL(save_stack_trace_tsk); 163 164 void save_stack_trace(struct stack_trace *trace) 165 { 166 save_stack_trace_tsk(NULL, trace); 167 } 168 EXPORT_SYMBOL_GPL(save_stack_trace); 169 170 #endif /* CONFIG_STACKTRACE */ 171