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 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                 fp = frame->fp;
  58                 pc = ftrace_graph_ret_addr(current, NULL, frame->ra,
  59                                            (unsigned long *)(fp - 8));
  60         }
  61 }
  62
  63 #else /* !CONFIG_FRAME_POINTER */
  64
  65 void notrace walk_stackframe(struct task_struct *task,
  66         struct pt_regs *regs, bool (*fn)(void *, unsigned long), void *arg)
  67 {
  68         unsigned long sp, pc;
  69         unsigned long *ksp;
  70
  71         if (regs) {
  72                 sp = user_stack_pointer(regs);
  73                 pc = instruction_pointer(regs);
  74         } else if (task == NULL || task == current) {
  75                 sp = sp_in_global;
  76                 pc = (unsigned long)walk_stackframe;
  77         } else {
  78                 /* task blocked in __switch_to */
  79                 sp = task->thread.sp;
  80                 pc = task->thread.ra;
  81         }
  82
  83         if (unlikely(sp & 0x7))
  84                 return;
  85
  86         ksp = (unsigned long *)sp;
  87         while (!kstack_end(ksp)) {
  88                 if (__kernel_text_address(pc) && unlikely(!fn(arg, pc)))
  89                         break;
  90                 pc = (*ksp++) - 0x4;
  91         }
  92 }
  93
  94 #endif /* CONFIG_FRAME_POINTER */
  95
  96 static bool print_trace_address(void *arg, unsigned long pc)
  97 {
  98         const char *loglvl = arg;
  99
 100         print_ip_sym(loglvl, pc);
 101         return true;
 102 }
 103
 104 void show_stack(struct task_struct *task, unsigned long *sp, const char *loglvl)
 105 {
 106         pr_cont("Call Trace:\n");
 107         walk_stackframe(task, NULL, print_trace_address, (void *)loglvl);
 108 }
 109
 110 static bool save_wchan(void *arg, unsigned long pc)
 111 {
 112         if (!in_sched_functions(pc)) {
 113                 unsigned long *p = arg;
 114                 *p = pc;
 115                 return false;
 116         }
 117         return true;
 118 }
 119
 120 unsigned long get_wchan(struct task_struct *task)
 121 {
 122         unsigned long pc = 0;
 123
 124         if (likely(task && task != current && task->state != TASK_RUNNING))
 125                 walk_stackframe(task, NULL, save_wchan, &pc);
 126         return pc;
 127 }
 128
 129 #ifdef CONFIG_STACKTRACE
 130
 131 void arch_stack_walk(stack_trace_consume_fn consume_entry, void *cookie,
 132                      struct task_struct *task, struct pt_regs *regs)
 133 {
 134         walk_stackframe(task, regs, consume_entry, cookie);
 135 }
 136
 137 #endif /* CONFIG_STACKTRACE */