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 register unsigned long sp_in_global __asm__("sp");
  16
  17 #ifdef CONFIG_FRAME_POINTER
  18
  19 struct stackframe {
  20         unsigned long fp;
  21         unsigned long ra;
  22 };
  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 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         const char *loglvl = arg;
 103
 104         print_ip_sym(loglvl, pc);
 105         return false;
 106 }
 107
 108 void show_stack(struct task_struct *task, unsigned long *sp, const char *loglvl)
 109 {
 110         pr_cont("Call Trace:\n");
 111         walk_stackframe(task, NULL, print_trace_address, (void *)loglvl);
 112 }
 113
 114 static bool save_wchan(unsigned long pc, void *arg)
 115 {
 116         if (!in_sched_functions(pc)) {
 117                 unsigned long *p = arg;
 118                 *p = pc;
 119                 return true;
 120         }
 121         return false;
 122 }
 123
 124 unsigned long get_wchan(struct task_struct *task)
 125 {
 126         unsigned long pc = 0;
 127
 128         if (likely(task && task != current && task->state != TASK_RUNNING))
 129                 walk_stackframe(task, NULL, save_wchan, &pc);
 130         return pc;
 131 }
 132
 133
 134 #ifdef CONFIG_STACKTRACE
 135
 136 static bool __save_trace(unsigned long pc, void *arg, bool nosched)
 137 {
 138         struct stack_trace *trace = arg;
 139
 140         if (unlikely(nosched && in_sched_functions(pc)))
 141                 return false;
 142         if (unlikely(trace->skip > 0)) {
 143                 trace->skip--;
 144                 return false;
 145         }
 146
 147         trace->entries[trace->nr_entries++] = pc;
 148         return (trace->nr_entries >= trace->max_entries);
 149 }
 150
 151 static bool save_trace(unsigned long pc, void *arg)
 152 {
 153         return __save_trace(pc, arg, false);
 154 }
 155
 156 /*
 157  * Save stack-backtrace addresses into a stack_trace buffer.
 158  */
 159 void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
 160 {
 161         walk_stackframe(tsk, NULL, save_trace, trace);
 162 }
 163 EXPORT_SYMBOL_GPL(save_stack_trace_tsk);
 164
 165 void save_stack_trace(struct stack_trace *trace)
 166 {
 167         save_stack_trace_tsk(NULL, trace);
 168 }
 169 EXPORT_SYMBOL_GPL(save_stack_trace);
 170
 171 #endif /* CONFIG_STACKTRACE */