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 #ifdef CONFIG_FRAME_POINTER
  16
  17 struct stackframe {
  18         unsigned long fp;
  19         unsigned long ra;
  20 };
  21
  22 void notrace walk_stackframe(struct task_struct *task, struct pt_regs *regs,
  23                              bool (*fn)(unsigned long, void *), void *arg)
  24 {
  25         unsigned long fp, sp, pc;
  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                 const register unsigned long current_sp __asm__ ("sp");
  33                 fp = (unsigned long)__builtin_frame_address(0);
  34                 sp = current_sp;
  35                 pc = (unsigned long)walk_stackframe;
  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) || fn(pc, arg)))
  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                 fp = frame->fp;
  59                 pc = ftrace_graph_ret_addr(current, NULL, frame->ra,
  60                                            (unsigned long *)(fp - 8));
  61         }
  62 }
  63
  64 #else /* !CONFIG_FRAME_POINTER */
  65
  66 void notrace walk_stackframe(struct task_struct *task,
  67         struct pt_regs *regs, bool (*fn)(unsigned long, void *), void *arg)
  68 {
  69         unsigned long sp, pc;
  70         unsigned long *ksp;
  71
  72         if (regs) {
  73                 sp = user_stack_pointer(regs);
  74                 pc = instruction_pointer(regs);
  75         } else if (task == NULL || task == current) {
  76                 const register unsigned long current_sp __asm__ ("sp");
  77                 sp = current_sp;
  78                 pc = (unsigned long)walk_stackframe;
  79         } else {
  80                 /* task blocked in __switch_to */
  81                 sp = task->thread.sp;
  82                 pc = task->thread.ra;
  83         }
  84
  85         if (unlikely(sp & 0x7))
  86                 return;
  87
  88         ksp = (unsigned long *)sp;
  89         while (!kstack_end(ksp)) {
  90                 if (__kernel_text_address(pc) && unlikely(fn(pc, arg)))
  91                         break;
  92                 pc = READ_ONCE_NOCHECK(*ksp++) - 0x4;
  93         }
  94 }
  95
  96 #endif /* CONFIG_FRAME_POINTER */
  97
  98
  99 static bool print_trace_address(unsigned long pc, void *arg)
 100 {
 101         print_ip_sym(pc);
 102         return false;
 103 }
 104
 105 void show_stack(struct task_struct *task, unsigned long *sp)
 106 {
 107         pr_cont("Call Trace:\n");
 108         walk_stackframe(task, NULL, print_trace_address, NULL);
 109 }
 110
 111
 112 static bool save_wchan(unsigned long pc, void *arg)
 113 {
 114         if (!in_sched_functions(pc)) {
 115                 unsigned long *p = arg;
 116                 *p = pc;
 117                 return true;
 118         }
 119         return false;
 120 }
 121
 122 unsigned long get_wchan(struct task_struct *task)
 123 {
 124         unsigned long pc = 0;
 125
 126         if (likely(task && task != current && task->state != TASK_RUNNING))
 127                 walk_stackframe(task, NULL, save_wchan, &pc);
 128         return pc;
 129 }
 130
 131
 132 #ifdef CONFIG_STACKTRACE
 133
 134 static bool __save_trace(unsigned long pc, void *arg, bool nosched)
 135 {
 136         struct stack_trace *trace = arg;
 137
 138         if (unlikely(nosched && in_sched_functions(pc)))
 139                 return false;
 140         if (unlikely(trace->skip > 0)) {
 141                 trace->skip--;
 142                 return false;
 143         }
 144
 145         trace->entries[trace->nr_entries++] = pc;
 146         return (trace->nr_entries >= trace->max_entries);
 147 }
 148
 149 static bool save_trace(unsigned long pc, void *arg)
 150 {
 151         return __save_trace(pc, arg, false);
 152 }
 153
 154 /*
 155  * Save stack-backtrace addresses into a stack_trace buffer.
 156  */
 157 void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
 158 {
 159         walk_stackframe(tsk, NULL, save_trace, trace);
 160 }
 161 EXPORT_SYMBOL_GPL(save_stack_trace_tsk);
 162
 163 void save_stack_trace(struct stack_trace *trace)
 164 {
 165         save_stack_trace_tsk(NULL, trace);
 166 }
 167 EXPORT_SYMBOL_GPL(save_stack_trace);
 168
 169 #endif /* CONFIG_STACKTRACE */