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