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 register unsigned long sp_in_global __asm__("sp");
  23
  24 void notrace walk_stackframe(struct task_struct *task, struct pt_regs *regs,
  25                              bool (*fn)(unsigned long, void *), void *arg)
  26 {
  27         unsigned long fp, sp, pc;
  28
  29         if (regs) {
  30                 fp = frame_pointer(regs);
  31                 sp = user_stack_pointer(regs);
  32                 pc = instruction_pointer(regs);
  33         } else if (task == NULL || task == current) {
  34                 const register unsigned long current_sp = sp_in_global;
  35                 fp = (unsigned long)__builtin_frame_address(0);
  36                 sp = current_sp;
  37                 pc = (unsigned long)walk_stackframe;
  38         } else {
  39                 /* task blocked in __switch_to */
  40                 fp = task->thread.s[0];
  41                 sp = task->thread.sp;
  42                 pc = task->thread.ra;
  43         }
  44
  45         for (;;) {
  46                 unsigned long low, high;
  47                 struct stackframe *frame;
  48
  49                 if (unlikely(!__kernel_text_address(pc) || fn(pc, arg)))
  50                         break;
  51
  52                 /* Validate frame pointer */
  53                 low = sp + sizeof(struct stackframe);
  54                 high = ALIGN(sp, THREAD_SIZE);
  55                 if (unlikely(fp < low || fp > high || fp & 0x7))
  56                         break;
  57                 /* Unwind stack frame */
  58                 frame = (struct stackframe *)fp - 1;
  59                 sp = fp;
  60                 fp = frame->fp;
  61                 pc = ftrace_graph_ret_addr(current, NULL, frame->ra,
  62                                            (unsigned long *)(fp - 8));
  63         }
  64 }
  65
  66 #else /* !CONFIG_FRAME_POINTER */
  67
  68 static void notrace walk_stackframe(struct task_struct *task,
  69         struct pt_regs *regs, bool (*fn)(unsigned long, void *), void *arg)
  70 {
  71         unsigned long sp, pc;
  72         unsigned long *ksp;
  73
  74         if (regs) {
  75                 sp = user_stack_pointer(regs);
  76                 pc = instruction_pointer(regs);
  77         } else if (task == NULL || task == current) {
  78                 sp = sp_in_global;
  79                 pc = (unsigned long)walk_stackframe;
  80         } else {
  81                 /* task blocked in __switch_to */
  82                 sp = task->thread.sp;
  83                 pc = task->thread.ra;
  84         }
  85
  86         if (unlikely(sp & 0x7))
  87                 return;
  88
  89         ksp = (unsigned long *)sp;
  90         while (!kstack_end(ksp)) {
  91                 if (__kernel_text_address(pc) && unlikely(fn(pc, arg)))
  92                         break;
  93                 pc = (*ksp++) - 0x4;
  94         }
  95 }
  96
  97 #endif /* CONFIG_FRAME_POINTER */
  98
  99
 100 static bool print_trace_address(unsigned long pc, void *arg)
 101 {
 102         print_ip_sym(pc);
 103         return false;
 104 }
 105
 106 void show_stack(struct task_struct *task, unsigned long *sp)
 107 {
 108         pr_cont("Call Trace:\n");
 109         walk_stackframe(task, NULL, print_trace_address, NULL);
 110 }
 111
 112
 113 static bool save_wchan(unsigned long pc, void *arg)
 114 {
 115         if (!in_sched_functions(pc)) {
 116                 unsigned long *p = arg;
 117                 *p = pc;
 118                 return true;
 119         }
 120         return false;
 121 }
 122
 123 unsigned long get_wchan(struct task_struct *task)
 124 {
 125         unsigned long pc = 0;
 126
 127         if (likely(task && task != current && task->state != TASK_RUNNING))
 128                 walk_stackframe(task, NULL, save_wchan, &pc);
 129         return pc;
 130 }
 131
 132
 133 #ifdef CONFIG_STACKTRACE
 134
 135 static bool __save_trace(unsigned long pc, void *arg, bool nosched)
 136 {
 137         struct stack_trace *trace = arg;
 138
 139         if (unlikely(nosched && in_sched_functions(pc)))
 140                 return false;
 141         if (unlikely(trace->skip > 0)) {
 142                 trace->skip--;
 143                 return false;
 144         }
 145
 146         trace->entries[trace->nr_entries++] = pc;
 147         return (trace->nr_entries >= trace->max_entries);
 148 }
 149
 150 static bool save_trace(unsigned long pc, void *arg)
 151 {
 152         return __save_trace(pc, arg, false);
 153 }
 154
 155 /*
 156  * Save stack-backtrace addresses into a stack_trace buffer.
 157  */
 158 void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
 159 {
 160         walk_stackframe(tsk, NULL, save_trace, trace);
 161 }
 162 EXPORT_SYMBOL_GPL(save_stack_trace_tsk);
 163
 164 void save_stack_trace(struct stack_trace *trace)
 165 {
 166         save_stack_trace_tsk(NULL, trace);
 167 }
 168 EXPORT_SYMBOL_GPL(save_stack_trace);
 169
 170 #endif /* CONFIG_STACKTRACE */