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 register unsigned long sp_in_global __asm__("sp");
  18
  19 #ifdef CONFIG_FRAME_POINTER
  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 = sp_in_global;
  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                                                    (unsigned long *)(fp - 8));
  64                 }
  65
  66         }
  67 }
  68
  69 #else /* !CONFIG_FRAME_POINTER */
  70
  71 void notrace walk_stackframe(struct task_struct *task,
  72         struct pt_regs *regs, bool (*fn)(void *, unsigned long), void *arg)
  73 {
  74         unsigned long sp, pc;
  75         unsigned long *ksp;
  76
  77         if (regs) {
  78                 sp = user_stack_pointer(regs);
  79                 pc = instruction_pointer(regs);
  80         } else if (task == NULL || task == current) {
  81                 sp = sp_in_global;
  82                 pc = (unsigned long)walk_stackframe;
  83         } else {
  84                 /* task blocked in __switch_to */
  85                 sp = task->thread.sp;
  86                 pc = task->thread.ra;
  87         }
  88
  89         if (unlikely(sp & 0x7))
  90                 return;
  91
  92         ksp = (unsigned long *)sp;
  93         while (!kstack_end(ksp)) {
  94                 if (__kernel_text_address(pc) && unlikely(!fn(arg, pc)))
  95                         break;
  96                 pc = (*ksp++) - 0x4;
  97         }
  98 }
  99
 100 #endif /* CONFIG_FRAME_POINTER */
 101
 102 static bool print_trace_address(void *arg, unsigned long pc)
 103 {
 104         const char *loglvl = arg;
 105
 106         print_ip_sym(loglvl, pc);
 107         return true;
 108 }
 109
 110 noinline void dump_backtrace(struct pt_regs *regs, struct task_struct *task,
 111                     const char *loglvl)
 112 {
 113         walk_stackframe(task, regs, print_trace_address, (void *)loglvl);
 114 }
 115
 116 void show_stack(struct task_struct *task, unsigned long *sp, const char *loglvl)
 117 {
 118         pr_cont("%sCall Trace:\n", loglvl);
 119         dump_backtrace(NULL, task, loglvl);
 120 }
 121
 122 static bool save_wchan(void *arg, unsigned long pc)
 123 {
 124         if (!in_sched_functions(pc)) {
 125                 unsigned long *p = arg;
 126                 *p = pc;
 127                 return false;
 128         }
 129         return true;
 130 }
 131
 132 unsigned long __get_wchan(struct task_struct *task)
 133 {
 134         unsigned long pc = 0;
 135
 136         if (!try_get_task_stack(task))
 137                 return 0;
 138         walk_stackframe(task, NULL, save_wchan, &pc);
 139         put_task_stack(task);
 140         return pc;
 141 }
 142
 143 noinline void arch_stack_walk(stack_trace_consume_fn consume_entry, void *cookie,
 144                      struct task_struct *task, struct pt_regs *regs)
 145 {
 146         walk_stackframe(task, regs, consume_entry, cookie);
 147 }