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 void notrace walk_stackframe(struct task_struct *task, struct pt_regs *regs,
  20                              bool (*fn)(void *, unsigned long), void *arg)
  21 {
  22         unsigned long fp, sp, pc;
  23         int level = 0;
  24
  25         if (regs) {
  26                 fp = frame_pointer(regs);
  27                 sp = user_stack_pointer(regs);
  28                 pc = instruction_pointer(regs);
  29         } else if (task == NULL || task == current) {
  30                 fp = (unsigned long)__builtin_frame_address(0);
  31                 sp = current_stack_pointer;
  32                 pc = (unsigned long)walk_stackframe;
  33         } else {
  34                 /* task blocked in __switch_to */
  35                 fp = task->thread.s[0];
  36                 sp = task->thread.sp;
  37                 pc = task->thread.ra;
  38         }
  39
  40         for (;;) {
  41                 unsigned long low, high;
  42                 struct stackframe *frame;
  43
  44                 if (unlikely(!__kernel_text_address(pc) || (level++ >= 1 && !fn(arg, pc))))
  45                         break;
  46
  47                 /* Validate frame pointer */
  48                 low = sp + sizeof(struct stackframe);
  49                 high = ALIGN(sp, THREAD_SIZE);
  50                 if (unlikely(fp < low || fp > high || fp & 0x7))
  51                         break;
  52                 /* Unwind stack frame */
  53                 frame = (struct stackframe *)fp - 1;
  54                 sp = fp;
  55                 if (regs && (regs->epc == pc) && (frame->fp & 0x7)) {
  56                         fp = frame->ra;
  57                         pc = regs->ra;
  58                 } else {
  59                         fp = frame->fp;
  60                         pc = ftrace_graph_ret_addr(current, NULL, frame->ra,
  61                                                    (unsigned long *)(fp - 8));
  62                 }
  63
  64         }
  65 }
  66
  67 #else /* !CONFIG_FRAME_POINTER */
  68
  69 void notrace walk_stackframe(struct task_struct *task,
  70         struct pt_regs *regs, bool (*fn)(void *, unsigned long), void *arg)
  71 {
  72         unsigned long sp, pc;
  73         unsigned long *ksp;
  74
  75         if (regs) {
  76                 sp = user_stack_pointer(regs);
  77                 pc = instruction_pointer(regs);
  78         } else if (task == NULL || task == current) {
  79                 sp = current_stack_pointer;
  80                 pc = (unsigned long)walk_stackframe;
  81         } else {
  82                 /* task blocked in __switch_to */
  83                 sp = task->thread.sp;
  84                 pc = task->thread.ra;
  85         }
  86
  87         if (unlikely(sp & 0x7))
  88                 return;
  89
  90         ksp = (unsigned long *)sp;
  91         while (!kstack_end(ksp)) {
  92                 if (__kernel_text_address(pc) && unlikely(!fn(arg, pc)))
  93                         break;
  94                 pc = (*ksp++) - 0x4;
  95         }
  96 }
  97
  98 #endif /* CONFIG_FRAME_POINTER */
  99
 100 static bool print_trace_address(void *arg, unsigned long pc)
 101 {
 102         const char *loglvl = arg;
 103
 104         print_ip_sym(loglvl, pc);
 105         return true;
 106 }
 107
 108 noinline void dump_backtrace(struct pt_regs *regs, struct task_struct *task,
 109                     const char *loglvl)
 110 {
 111         walk_stackframe(task, regs, print_trace_address, (void *)loglvl);
 112 }
 113
 114 void show_stack(struct task_struct *task, unsigned long *sp, const char *loglvl)
 115 {
 116         pr_cont("%sCall Trace:\n", loglvl);
 117         dump_backtrace(NULL, task, loglvl);
 118 }
 119
 120 static bool save_wchan(void *arg, unsigned long pc)
 121 {
 122         if (!in_sched_functions(pc)) {
 123                 unsigned long *p = arg;
 124                 *p = pc;
 125                 return false;
 126         }
 127         return true;
 128 }
 129
 130 unsigned long __get_wchan(struct task_struct *task)
 131 {
 132         unsigned long pc = 0;
 133
 134         if (!try_get_task_stack(task))
 135                 return 0;
 136         walk_stackframe(task, NULL, save_wchan, &pc);
 137         put_task_stack(task);
 138         return pc;
 139 }
 140
 141 noinline void arch_stack_walk(stack_trace_consume_fn consume_entry, void *cookie,
 142                      struct task_struct *task, struct pt_regs *regs)
 143 {
 144         walk_stackframe(task, regs, consume_entry, cookie);
 145 }