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 register unsigned long sp_in_global __asm__("sp"); 18 19 #ifdef CONFIG_FRAME_POINTER 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 26 if (regs) { 27 fp = frame_pointer(regs); 28 sp = user_stack_pointer(regs); 29 pc = instruction_pointer(regs); 30 } else if (task == NULL || task == current) { 31 const register unsigned long current_sp = sp_in_global; 32 fp = (unsigned long)__builtin_frame_address(0); 33 sp = current_sp; 34 pc = (unsigned long)walk_stackframe; 35 } else { 36 /* task blocked in __switch_to */ 37 fp = task->thread.s[0]; 38 sp = task->thread.sp; 39 pc = task->thread.ra; 40 } 41 42 for (;;) { 43 unsigned long low, high; 44 struct stackframe *frame; 45 46 if (unlikely(!__kernel_text_address(pc) || !fn(arg, pc))) 47 break; 48 49 /* Validate frame pointer */ 50 low = sp + sizeof(struct stackframe); 51 high = ALIGN(sp, THREAD_SIZE); 52 if (unlikely(fp < low || fp > high || fp & 0x7)) 53 break; 54 /* Unwind stack frame */ 55 frame = (struct stackframe *)fp - 1; 56 sp = fp; 57 if (regs && (regs->epc == pc) && (frame->fp & 0x7)) { 58 fp = frame->ra; 59 pc = regs->ra; 60 } else { 61 fp = frame->fp; 62 pc = ftrace_graph_ret_addr(current, NULL, frame->ra, 63 (unsigned long *)(fp - 8)); 64 } 65 66 } 67 } 68 69 #else /* !CONFIG_FRAME_POINTER */ 70 71 void notrace walk_stackframe(struct task_struct *task, 72 struct pt_regs *regs, bool (*fn)(void *, unsigned long), void *arg) 73 { 74 unsigned long sp, pc; 75 unsigned long *ksp; 76 77 if (regs) { 78 sp = user_stack_pointer(regs); 79 pc = instruction_pointer(regs); 80 } else if (task == NULL || task == current) { 81 sp = sp_in_global; 82 pc = (unsigned long)walk_stackframe; 83 } else { 84 /* task blocked in __switch_to */ 85 sp = task->thread.sp; 86 pc = task->thread.ra; 87 } 88 89 if (unlikely(sp & 0x7)) 90 return; 91 92 ksp = (unsigned long *)sp; 93 while (!kstack_end(ksp)) { 94 if (__kernel_text_address(pc) && unlikely(!fn(arg, pc))) 95 break; 96 pc = (*ksp++) - 0x4; 97 } 98 } 99 100 #endif /* CONFIG_FRAME_POINTER */ 101 102 static bool print_trace_address(void *arg, unsigned long pc) 103 { 104 const char *loglvl = arg; 105 106 print_ip_sym(loglvl, pc); 107 return true; 108 } 109 110 void dump_backtrace(struct pt_regs *regs, struct task_struct *task, 111 const char *loglvl) 112 { 113 pr_cont("%sCall Trace:\n", loglvl); 114 walk_stackframe(task, regs, print_trace_address, (void *)loglvl); 115 } 116 117 void show_stack(struct task_struct *task, unsigned long *sp, const char *loglvl) 118 { 119 dump_backtrace(NULL, task, loglvl); 120 } 121 122 static bool save_wchan(void *arg, unsigned long pc) 123 { 124 if (!in_sched_functions(pc)) { 125 unsigned long *p = arg; 126 *p = pc; 127 return false; 128 } 129 return true; 130 } 131 132 unsigned long get_wchan(struct task_struct *task) 133 { 134 unsigned long pc = 0; 135 136 if (likely(task && task != current && task->state != TASK_RUNNING)) 137 walk_stackframe(task, NULL, save_wchan, &pc); 138 return pc; 139 } 140 141 #ifdef CONFIG_STACKTRACE 142 143 void arch_stack_walk(stack_trace_consume_fn consume_entry, void *cookie, 144 struct task_struct *task, struct pt_regs *regs) 145 { 146 walk_stackframe(task, regs, consume_entry, cookie); 147 } 148 149 #endif /* CONFIG_STACKTRACE */ 150