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 #include <asm/stacktrace.h>
  16
  17 #ifdef CONFIG_FRAME_POINTER
  18
  19 extern asmlinkage void ret_from_exception(void);
  20
  21 void notrace walk_stackframe(struct task_struct *task, struct pt_regs *regs,
  22                              bool (*fn)(void *, unsigned long), void *arg)
  23 {
  24         unsigned long fp, sp, pc;
  25         int level = 0;
  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                 fp = (unsigned long)__builtin_frame_address(0);
  33                 sp = current_stack_pointer;
  34                 pc = (unsigned long)walk_stackframe;
  35         } else {
  36                 /* task blocked in __switch_to */
  37                 fp = task->thread.s[0];
  38                 sp = task->thread.sp;
  39                 pc = task->thread.ra;
  40         }
  41
  42         for (;;) {
  43                 unsigned long low, high;
  44                 struct stackframe *frame;
  45
  46                 if (unlikely(!__kernel_text_address(pc) || (level++ >= 1 && !fn(arg, pc))))
  47                         break;
  48
  49                 /* Validate frame pointer */
  50                 low = sp + sizeof(struct stackframe);
  51                 high = ALIGN(sp, THREAD_SIZE);
  52                 if (unlikely(fp < low || fp > high || fp & 0x7))
  53                         break;
  54                 /* Unwind stack frame */
  55                 frame = (struct stackframe *)fp - 1;
  56                 sp = fp;
  57                 if (regs && (regs->epc == pc) && (frame->fp & 0x7)) {
  58                         fp = frame->ra;
  59                         pc = regs->ra;
  60                 } else {
  61                         fp = frame->fp;
  62                         pc = ftrace_graph_ret_addr(current, NULL, frame->ra,
  63                                                    &frame->ra);
  64                         if (pc == (unsigned long)ret_from_exception) {
  65                                 if (unlikely(!__kernel_text_address(pc) || !fn(arg, pc)))
  66                                         break;
  67
  68                                 pc = ((struct pt_regs *)sp)->epc;
  69                                 fp = ((struct pt_regs *)sp)->s0;
  70                         }
  71                 }
  72
  73         }
  74 }
  75
  76 #else /* !CONFIG_FRAME_POINTER */
  77
  78 void notrace walk_stackframe(struct task_struct *task,
  79         struct pt_regs *regs, bool (*fn)(void *, unsigned long), void *arg)
  80 {
  81         unsigned long sp, pc;
  82         unsigned long *ksp;
  83
  84         if (regs) {
  85                 sp = user_stack_pointer(regs);
  86                 pc = instruction_pointer(regs);
  87         } else if (task == NULL || task == current) {
  88                 sp = current_stack_pointer;
  89                 pc = (unsigned long)walk_stackframe;
  90         } else {
  91                 /* task blocked in __switch_to */
  92                 sp = task->thread.sp;
  93                 pc = task->thread.ra;
  94         }
  95
  96         if (unlikely(sp & 0x7))
  97                 return;
  98
  99         ksp = (unsigned long *)sp;
 100         while (!kstack_end(ksp)) {
 101                 if (__kernel_text_address(pc) && unlikely(!fn(arg, pc)))
 102                         break;
 103                 pc = (*ksp++) - 0x4;
 104         }
 105 }
 106
 107 #endif /* CONFIG_FRAME_POINTER */
 108
 109 static bool print_trace_address(void *arg, unsigned long pc)
 110 {
 111         const char *loglvl = arg;
 112
 113         print_ip_sym(loglvl, pc);
 114         return true;
 115 }
 116
 117 noinline void dump_backtrace(struct pt_regs *regs, struct task_struct *task,
 118                     const char *loglvl)
 119 {
 120         walk_stackframe(task, regs, print_trace_address, (void *)loglvl);
 121 }
 122
 123 void show_stack(struct task_struct *task, unsigned long *sp, const char *loglvl)
 124 {
 125         pr_cont("%sCall Trace:\n", loglvl);
 126         dump_backtrace(NULL, task, loglvl);
 127 }
 128
 129 static bool save_wchan(void *arg, unsigned long pc)
 130 {
 131         if (!in_sched_functions(pc)) {
 132                 unsigned long *p = arg;
 133                 *p = pc;
 134                 return false;
 135         }
 136         return true;
 137 }
 138
 139 unsigned long __get_wchan(struct task_struct *task)
 140 {
 141         unsigned long pc = 0;
 142
 143         if (!try_get_task_stack(task))
 144                 return 0;
 145         walk_stackframe(task, NULL, save_wchan, &pc);
 146         put_task_stack(task);
 147         return pc;
 148 }
 149
 150 noinline void arch_stack_walk(stack_trace_consume_fn consume_entry, void *cookie,
 151                      struct task_struct *task, struct pt_regs *regs)
 152 {
 153         walk_stackframe(task, regs, consume_entry, cookie);
 154 }