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 #include <linux/ftrace.h>
  22
  23 #ifdef CONFIG_FRAME_POINTER
  24
  25 struct stackframe {
  26         unsigned long fp;
  27         unsigned long ra;
  28 };
  29
  30 static void notrace walk_stackframe(struct task_struct *task,
  31         struct pt_regs *regs, bool (*fn)(unsigned long, void *), void *arg)
  32 {
  33         unsigned long fp, sp, pc;
  34
  35         if (regs) {
  36                 fp = GET_FP(regs);
  37                 sp = GET_USP(regs);
  38                 pc = GET_IP(regs);
  39         } else if (task == NULL || task == current) {
  40                 const register unsigned long current_sp __asm__ ("sp");
  41                 fp = (unsigned long)__builtin_frame_address(0);
  42                 sp = current_sp;
  43                 pc = (unsigned long)walk_stackframe;
  44         } else {
  45                 /* task blocked in __switch_to */
  46                 fp = task->thread.s[0];
  47                 sp = task->thread.sp;
  48                 pc = task->thread.ra;
  49         }
  50
  51         for (;;) {
  52                 unsigned long low, high;
  53                 struct stackframe *frame;
  54
  55                 if (unlikely(!__kernel_text_address(pc) || fn(pc, arg)))
  56                         break;
  57
  58                 /* Validate frame pointer */
  59                 low = sp + sizeof(struct stackframe);
  60                 high = ALIGN(sp, THREAD_SIZE);
  61                 if (unlikely(fp < low || fp > high || fp & 0x7))
  62                         break;
  63                 /* Unwind stack frame */
  64                 frame = (struct stackframe *)fp - 1;
  65                 sp = fp;
  66                 fp = frame->fp;
  67 #ifdef HAVE_FUNCTION_GRAPH_RET_ADDR_PTR
  68                 pc = ftrace_graph_ret_addr(current, NULL, frame->ra,
  69                                            (unsigned long *)(fp - 8));
  70 #else
  71                 pc = frame->ra - 0x4;
  72 #endif
  73         }
  74 }
  75
  76 #else /* !CONFIG_FRAME_POINTER */
  77
  78 static void notrace walk_stackframe(struct task_struct *task,
  79         struct pt_regs *regs, bool (*fn)(unsigned long, void *), void *arg)
  80 {
  81         unsigned long sp, pc;
  82         unsigned long *ksp;
  83
  84         if (regs) {
  85                 sp = GET_USP(regs);
  86                 pc = GET_IP(regs);
  87         } else if (task == NULL || task == current) {
  88                 const register unsigned long current_sp __asm__ ("sp");
  89                 sp = current_sp;
  90                 pc = (unsigned long)walk_stackframe;
  91         } else {
  92                 /* task blocked in __switch_to */
  93                 sp = task->thread.sp;
  94                 pc = task->thread.ra;
  95         }
  96
  97         if (unlikely(sp & 0x7))
  98                 return;
  99
 100         ksp = (unsigned long *)sp;
 101         while (!kstack_end(ksp)) {
 102                 if (__kernel_text_address(pc) && unlikely(fn(pc, arg)))
 103                         break;
 104                 pc = (*ksp++) - 0x4;
 105         }
 106 }
 107
 108 #endif /* CONFIG_FRAME_POINTER */
 109
 110
 111 static bool print_trace_address(unsigned long pc, void *arg)
 112 {
 113         print_ip_sym(pc);
 114         return false;
 115 }
 116
 117 void show_stack(struct task_struct *task, unsigned long *sp)
 118 {
 119         pr_cont("Call Trace:\n");
 120         walk_stackframe(task, NULL, print_trace_address, NULL);
 121 }
 122
 123
 124 static bool save_wchan(unsigned long pc, void *arg)
 125 {
 126         if (!in_sched_functions(pc)) {
 127                 unsigned long *p = arg;
 128                 *p = pc;
 129                 return true;
 130         }
 131         return false;
 132 }
 133
 134 unsigned long get_wchan(struct task_struct *task)
 135 {
 136         unsigned long pc = 0;
 137
 138         if (likely(task && task != current && task->state != TASK_RUNNING))
 139                 walk_stackframe(task, NULL, save_wchan, &pc);
 140         return pc;
 141 }
 142
 143
 144 #ifdef CONFIG_STACKTRACE
 145
 146 static bool __save_trace(unsigned long pc, void *arg, bool nosched)
 147 {
 148         struct stack_trace *trace = arg;
 149
 150         if (unlikely(nosched && in_sched_functions(pc)))
 151                 return false;
 152         if (unlikely(trace->skip > 0)) {
 153                 trace->skip--;
 154                 return false;
 155         }
 156
 157         trace->entries[trace->nr_entries++] = pc;
 158         return (trace->nr_entries >= trace->max_entries);
 159 }
 160
 161 static bool save_trace(unsigned long pc, void *arg)
 162 {
 163         return __save_trace(pc, arg, false);
 164 }
 165
 166 /*
 167  * Save stack-backtrace addresses into a stack_trace buffer.
 168  */
 169 void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
 170 {
 171         walk_stackframe(tsk, NULL, save_trace, trace);
 172 }
 173 EXPORT_SYMBOL_GPL(save_stack_trace_tsk);
 174
 175 void save_stack_trace(struct stack_trace *trace)
 176 {
 177         save_stack_trace_tsk(NULL, trace);
 178 }
 179 EXPORT_SYMBOL_GPL(save_stack_trace);
 180
 181 #endif /* CONFIG_STACKTRACE */