arch/riscv/kernel/stacktrace.c

   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 extern asmlinkage void ret_from_exception(void);
  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         int level = 0;
  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                 fp = (unsigned long)__builtin_frame_address(0);
  33                 sp = current_stack_pointer;
  34                 pc = (unsigned long)walk_stackframe;
  35                 level = -1;
  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) || (level++ >= 0 && !fn(arg, pc))))
  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                 if (regs && (regs->epc == pc) && (frame->fp & 0x7)) {
  59                         fp = frame->ra;
  60                         pc = regs->ra;
  61                 } else {
  62                         fp = frame->fp;
  63                         pc = ftrace_graph_ret_addr(current, NULL, frame->ra,
  64                                                    &frame->ra);
  65                         if (pc == (unsigned long)ret_from_exception) {
  66                                 if (unlikely(!__kernel_text_address(pc) || !fn(arg, pc)))
  67                                         break;
  68
  69                                 pc = ((struct pt_regs *)sp)->epc;
  70                                 fp = ((struct pt_regs *)sp)->s0;
  71                         }
  72                 }
  73
  74         }
  75 }
  76
  77 #else /* !CONFIG_FRAME_POINTER */
  78
  79 void notrace walk_stackframe(struct task_struct *task,
  80         struct pt_regs *regs, bool (*fn)(void *, unsigned long), void *arg)
  81 {
  82         unsigned long sp, pc;
  83         unsigned long *ksp;
  84
  85         if (regs) {
  86                 sp = user_stack_pointer(regs);
  87                 pc = instruction_pointer(regs);
  88         } else if (task == NULL || task == current) {
  89                 sp = current_stack_pointer;
  90                 pc = (unsigned long)walk_stackframe;
  91         } else {
  92                 /* task blocked in __switch_to */
  93                 sp = task->thread.sp;
  94                 pc = task->thread.ra;
  95         }
  96
  97         if (unlikely(sp & 0x7))
  98                 return;
  99
 100         ksp = (unsigned long *)sp;
 101         while (!kstack_end(ksp)) {
 102                 if (__kernel_text_address(pc) && unlikely(!fn(arg, pc)))
 103                         break;
 104                 pc = READ_ONCE_NOCHECK(*ksp++) - 0x4;
 105         }
 106 }
 107
 108 #endif /* CONFIG_FRAME_POINTER */
 109
 110 static bool print_trace_address(void *arg, unsigned long pc)
 111 {
 112         const char *loglvl = arg;
 113
 114         print_ip_sym(loglvl, pc);
 115         return true;
 116 }
 117
 118 noinline void dump_backtrace(struct pt_regs *regs, struct task_struct *task,
 119                     const char *loglvl)
 120 {
 121         walk_stackframe(task, regs, print_trace_address, (void *)loglvl);
 122 }
 123
 124 void show_stack(struct task_struct *task, unsigned long *sp, const char *loglvl)
 125 {
 126         pr_cont("%sCall Trace:\n", loglvl);
 127         dump_backtrace(NULL, task, loglvl);
 128 }
 129
 130 static bool save_wchan(void *arg, unsigned long pc)
 131 {
 132         if (!in_sched_functions(pc)) {
 133                 unsigned long *p = arg;
 134                 *p = pc;
 135                 return false;
 136         }
 137         return true;
 138 }
 139
 140 unsigned long __get_wchan(struct task_struct *task)
 141 {
 142         unsigned long pc = 0;
 143
 144         if (!try_get_task_stack(task))
 145                 return 0;
 146         walk_stackframe(task, NULL, save_wchan, &pc);
 147         put_task_stack(task);
 148         return pc;
 149 }
 150
 151 noinline void arch_stack_walk(stack_trace_consume_fn consume_entry, void *cookie,
 152                      struct task_struct *task, struct pt_regs *regs)
 153 {
 154         walk_stackframe(task, regs, consume_entry, cookie);
 155 }