arch/riscv/kernel/stacktrace.c

   1 /*
   2  * Copyright (C) 2008 ARM Limited
   3  * Copyright (C) 2014 Regents of the University of California
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License version 2 as
   7  * published by the Free Software Foundation.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  */
  14
  15 #include <linux/export.h>
  16 #include <linux/kallsyms.h>
  17 #include <linux/sched.h>
  18 #include <linux/sched/debug.h>
  19 #include <linux/sched/task_stack.h>
  20 #include <linux/stacktrace.h>
  21
  22 #ifdef CONFIG_FRAME_POINTER
  23
  24 struct stackframe {
  25         unsigned long fp;
  26         unsigned long ra;
  27 };
  28
  29 static void notrace walk_stackframe(struct task_struct *task,
  30         struct pt_regs *regs, bool (*fn)(unsigned long, void *), void *arg)
  31 {
  32         unsigned long fp, sp, pc;
  33
  34         if (regs) {
  35                 fp = GET_FP(regs);
  36                 sp = GET_USP(regs);
  37                 pc = GET_IP(regs);
  38         } else if (task == NULL || task == current) {
  39                 const register unsigned long current_sp __asm__ ("sp");
  40                 fp = (unsigned long)__builtin_frame_address(0);
  41                 sp = current_sp;
  42                 pc = (unsigned long)walk_stackframe;
  43         } else {
  44                 /* task blocked in __switch_to */
  45                 fp = task->thread.s[0];
  46                 sp = task->thread.sp;
  47                 pc = task->thread.ra;
  48         }
  49
  50         for (;;) {
  51                 unsigned long low, high;
  52                 struct stackframe *frame;
  53
  54                 if (unlikely(!__kernel_text_address(pc) || fn(pc, arg)))
  55                         break;
  56
  57                 /* Validate frame pointer */
  58                 low = sp + sizeof(struct stackframe);
  59                 high = ALIGN(sp, THREAD_SIZE);
  60                 if (unlikely(fp < low || fp > high || fp & 0x7))
  61                         break;
  62                 /* Unwind stack frame */
  63                 frame = (struct stackframe *)fp - 1;
  64                 sp = fp;
  65                 fp = frame->fp;
  66                 pc = frame->ra - 0x4;
  67         }
  68 }
  69
  70 #else /* !CONFIG_FRAME_POINTER */
  71
  72 static void notrace walk_stackframe(struct task_struct *task,
  73         struct pt_regs *regs, bool (*fn)(unsigned long, void *), void *arg)
  74 {
  75         unsigned long sp, pc;
  76         unsigned long *ksp;
  77
  78         if (regs) {
  79                 sp = GET_USP(regs);
  80                 pc = GET_IP(regs);
  81         } else if (task == NULL || task == current) {
  82                 const register unsigned long current_sp __asm__ ("sp");
  83                 sp = current_sp;
  84                 pc = (unsigned long)walk_stackframe;
  85         } else {
  86                 /* task blocked in __switch_to */
  87                 sp = task->thread.sp;
  88                 pc = task->thread.ra;
  89         }
  90
  91         if (unlikely(sp & 0x7))
  92                 return;
  93
  94         ksp = (unsigned long *)sp;
  95         while (!kstack_end(ksp)) {
  96                 if (__kernel_text_address(pc) && unlikely(fn(pc, arg)))
  97                         break;
  98                 pc = (*ksp++) - 0x4;
  99         }
 100 }
 101
 102 #endif /* CONFIG_FRAME_POINTER */
 103
 104
 105 static bool print_trace_address(unsigned long pc, void *arg)
 106 {
 107         print_ip_sym(pc);
 108         return false;
 109 }
 110
 111 void show_stack(struct task_struct *task, unsigned long *sp)
 112 {
 113         pr_cont("Call Trace:\n");
 114         walk_stackframe(task, NULL, print_trace_address, NULL);
 115 }
 116
 117
 118 static bool save_wchan(unsigned long pc, void *arg)
 119 {
 120         if (!in_sched_functions(pc)) {
 121                 unsigned long *p = arg;
 122                 *p = pc;
 123                 return true;
 124         }
 125         return false;
 126 }
 127
 128 unsigned long get_wchan(struct task_struct *task)
 129 {
 130         unsigned long pc = 0;
 131
 132         if (likely(task && task != current && task->state != TASK_RUNNING))
 133                 walk_stackframe(task, NULL, save_wchan, &pc);
 134         return pc;
 135 }
 136
 137
 138 #ifdef CONFIG_STACKTRACE
 139
 140 static bool __save_trace(unsigned long pc, void *arg, bool nosched)
 141 {
 142         struct stack_trace *trace = arg;
 143
 144         if (unlikely(nosched && in_sched_functions(pc)))
 145                 return false;
 146         if (unlikely(trace->skip > 0)) {
 147                 trace->skip--;
 148                 return false;
 149         }
 150
 151         trace->entries[trace->nr_entries++] = pc;
 152         return (trace->nr_entries >= trace->max_entries);
 153 }
 154
 155 static bool save_trace(unsigned long pc, void *arg)
 156 {
 157         return __save_trace(pc, arg, false);
 158 }
 159
 160 /*
 161  * Save stack-backtrace addresses into a stack_trace buffer.
 162  */
 163 void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
 164 {
 165         walk_stackframe(tsk, NULL, save_trace, trace);
 166         if (trace->nr_entries < trace->max_entries)
 167                 trace->entries[trace->nr_entries++] = ULONG_MAX;
 168 }
 169 EXPORT_SYMBOL_GPL(save_stack_trace_tsk);
 170
 171 void save_stack_trace(struct stack_trace *trace)
 172 {
 173         save_stack_trace_tsk(NULL, trace);
 174 }
 175 EXPORT_SYMBOL_GPL(save_stack_trace);
 176
 177 #endif /* CONFIG_STACKTRACE */