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 fp = (unsigned long)__builtin_frame_address(1); 32 sp = (unsigned long)__builtin_frame_address(0); 33 pc = (unsigned long)__builtin_return_address(0); 34 } else { 35 /* task blocked in __switch_to */ 36 fp = task->thread.s[0]; 37 sp = task->thread.sp; 38 pc = task->thread.ra; 39 } 40 41 for (;;) { 42 unsigned long low, high; 43 struct stackframe *frame; 44 45 if (unlikely(!__kernel_text_address(pc) || !fn(arg, pc))) 46 break; 47 48 /* Validate frame pointer */ 49 low = sp + sizeof(struct stackframe); 50 high = ALIGN(sp, THREAD_SIZE); 51 if (unlikely(fp < low || fp > high || fp & 0x7)) 52 break; 53 /* Unwind stack frame */ 54 frame = (struct stackframe *)fp - 1; 55 sp = fp; 56 if (regs && (regs->epc == pc) && (frame->fp & 0x7)) { 57 fp = frame->ra; 58 pc = regs->ra; 59 } else { 60 fp = frame->fp; 61 pc = ftrace_graph_ret_addr(current, NULL, frame->ra, 62 (unsigned long *)(fp - 8)); 63 } 64 65 } 66 } 67 68 #else /* !CONFIG_FRAME_POINTER */ 69 70 void notrace walk_stackframe(struct task_struct *task, 71 struct pt_regs *regs, bool (*fn)(void *, unsigned long), void *arg) 72 { 73 unsigned long sp, pc; 74 unsigned long *ksp; 75 76 if (regs) { 77 sp = user_stack_pointer(regs); 78 pc = instruction_pointer(regs); 79 } else if (task == NULL || task == current) { 80 sp = sp_in_global; 81 pc = (unsigned long)walk_stackframe; 82 } else { 83 /* task blocked in __switch_to */ 84 sp = task->thread.sp; 85 pc = task->thread.ra; 86 } 87 88 if (unlikely(sp & 0x7)) 89 return; 90 91 ksp = (unsigned long *)sp; 92 while (!kstack_end(ksp)) { 93 if (__kernel_text_address(pc) && unlikely(!fn(arg, pc))) 94 break; 95 pc = (*ksp++) - 0x4; 96 } 97 } 98 99 #endif /* CONFIG_FRAME_POINTER */ 100 101 static bool print_trace_address(void *arg, unsigned long pc) 102 { 103 const char *loglvl = arg; 104 105 print_ip_sym(loglvl, pc); 106 return true; 107 } 108 109 noinline void dump_backtrace(struct pt_regs *regs, struct task_struct *task, 110 const char *loglvl) 111 { 112 walk_stackframe(task, regs, print_trace_address, (void *)loglvl); 113 } 114 115 void show_stack(struct task_struct *task, unsigned long *sp, const char *loglvl) 116 { 117 pr_cont("%sCall Trace:\n", loglvl); 118 dump_backtrace(NULL, task, loglvl); 119 } 120 121 static bool save_wchan(void *arg, unsigned long pc) 122 { 123 if (!in_sched_functions(pc)) { 124 unsigned long *p = arg; 125 *p = pc; 126 return false; 127 } 128 return true; 129 } 130 131 unsigned long __get_wchan(struct task_struct *task) 132 { 133 unsigned long pc = 0; 134 135 if (!try_get_task_stack(task)) 136 return 0; 137 walk_stackframe(task, NULL, save_wchan, &pc); 138 put_task_stack(task); 139 return pc; 140 } 141 142 #ifdef CONFIG_STACKTRACE 143 144 noinline void arch_stack_walk(stack_trace_consume_fn consume_entry, void *cookie, 145 struct task_struct *task, struct pt_regs *regs) 146 { 147 walk_stackframe(task, regs, consume_entry, cookie); 148 } 149 150 #endif /* CONFIG_STACKTRACE */ 151