arch/csky/kernel/stacktrace.c

   1 // SPDX-License-Identifier: GPL-2.0
   2
   3 #include <linux/sched/debug.h>
   4 #include <linux/sched/task_stack.h>
   5 #include <linux/stacktrace.h>
   6 #include <linux/ftrace.h>
   7 #include <linux/ptrace.h>
   8
   9 #ifdef CONFIG_FRAME_POINTER
  10
  11 struct stackframe {
  12         unsigned long fp;
  13         unsigned long ra;
  14 };
  15
  16 void notrace walk_stackframe(struct task_struct *task, struct pt_regs *regs,
  17                              bool (*fn)(unsigned long, void *), void *arg)
  18 {
  19         unsigned long fp, sp, pc;
  20
  21         if (regs) {
  22                 fp = frame_pointer(regs);
  23                 sp = user_stack_pointer(regs);
  24                 pc = instruction_pointer(regs);
  25         } else if (task == NULL || task == current) {
  26                 const register unsigned long current_fp __asm__ ("r8");
  27                 fp = current_fp;
  28                 sp = current_stack_pointer;
  29                 pc = (unsigned long)walk_stackframe;
  30         } else {
  31                 /* task blocked in __switch_to */
  32                 fp = thread_saved_fp(task);
  33                 sp = thread_saved_sp(task);
  34                 pc = thread_saved_lr(task);
  35         }
  36
  37         for (;;) {
  38                 unsigned long low, high;
  39                 struct stackframe *frame;
  40
  41                 if (unlikely(!__kernel_text_address(pc) || fn(pc, arg)))
  42                         break;
  43
  44                 /* Validate frame pointer */
  45                 low = sp;
  46                 high = ALIGN(sp, THREAD_SIZE);
  47                 if (unlikely(fp < low || fp > high || fp & 0x3))
  48                         break;
  49                 /* Unwind stack frame */
  50                 frame = (struct stackframe *)fp;
  51                 sp = fp;
  52                 fp = frame->fp;
  53                 pc = ftrace_graph_ret_addr(current, NULL, frame->ra,
  54                                            (unsigned long *)(fp - 8));
  55         }
  56 }
  57
  58 #else /* !CONFIG_FRAME_POINTER */
  59
  60 static void notrace walk_stackframe(struct task_struct *task,
  61         struct pt_regs *regs, bool (*fn)(unsigned long, void *), void *arg)
  62 {
  63         unsigned long sp, pc;
  64         unsigned long *ksp;
  65
  66         if (regs) {
  67                 sp = user_stack_pointer(regs);
  68                 pc = instruction_pointer(regs);
  69         } else if (task == NULL || task == current) {
  70                 sp = current_stack_pointer;
  71                 pc = (unsigned long)walk_stackframe;
  72         } else {
  73                 /* task blocked in __switch_to */
  74                 sp = thread_saved_sp(task);
  75                 pc = thread_saved_lr(task);
  76         }
  77
  78         if (unlikely(sp & 0x3))
  79                 return;
  80
  81         ksp = (unsigned long *)sp;
  82         while (!kstack_end(ksp)) {
  83                 if (__kernel_text_address(pc) && unlikely(fn(pc, arg)))
  84                         break;
  85                 pc = (*ksp++) - 0x4;
  86         }
  87 }
  88 #endif /* CONFIG_FRAME_POINTER */
  89
  90 static bool print_trace_address(unsigned long pc, void *arg)
  91 {
  92         print_ip_sym((const char *)arg, pc);
  93         return false;
  94 }
  95
  96 void show_stack(struct task_struct *task, unsigned long *sp, const char *loglvl)
  97 {
  98         pr_cont("Call Trace:\n");
  99         walk_stackframe(task, NULL, print_trace_address, (void *)loglvl);
 100 }
 101
 102 static bool save_wchan(unsigned long pc, void *arg)
 103 {
 104         if (!in_sched_functions(pc)) {
 105                 unsigned long *p = arg;
 106                 *p = pc;
 107                 return true;
 108         }
 109         return false;
 110 }
 111
 112 unsigned long __get_wchan(struct task_struct *task)
 113 {
 114         unsigned long pc = 0;
 115
 116         walk_stackframe(task, NULL, save_wchan, &pc);
 117         return pc;
 118 }
 119
 120 #ifdef CONFIG_STACKTRACE
 121 static bool __save_trace(unsigned long pc, void *arg, bool nosched)
 122 {
 123         struct stack_trace *trace = arg;
 124
 125         if (unlikely(nosched && in_sched_functions(pc)))
 126                 return false;
 127         if (unlikely(trace->skip > 0)) {
 128                 trace->skip--;
 129                 return false;
 130         }
 131
 132         trace->entries[trace->nr_entries++] = pc;
 133         return (trace->nr_entries >= trace->max_entries);
 134 }
 135
 136 static bool save_trace(unsigned long pc, void *arg)
 137 {
 138         return __save_trace(pc, arg, false);
 139 }
 140
 141 /*
 142  * Save stack-backtrace addresses into a stack_trace buffer.
 143  */
 144 void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
 145 {
 146         walk_stackframe(tsk, NULL, save_trace, trace);
 147 }
 148 EXPORT_SYMBOL_GPL(save_stack_trace_tsk);
 149
 150 void save_stack_trace(struct stack_trace *trace)
 151 {
 152         save_stack_trace_tsk(NULL, trace);
 153 }
 154 EXPORT_SYMBOL_GPL(save_stack_trace);
 155
 156 #endif /* CONFIG_STACKTRACE */