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_sp __asm__ ("sp");
  27                 const register unsigned long current_fp __asm__ ("r8");
  28                 fp = current_fp;
  29                 sp = current_sp;
  30                 pc = (unsigned long)walk_stackframe;
  31         } else {
  32                 /* task blocked in __switch_to */
  33                 fp = thread_saved_fp(task);
  34                 sp = thread_saved_sp(task);
  35                 pc = thread_saved_lr(task);
  36         }
  37
  38         for (;;) {
  39                 unsigned long low, high;
  40                 struct stackframe *frame;
  41
  42                 if (unlikely(!__kernel_text_address(pc) || fn(pc, arg)))
  43                         break;
  44
  45                 /* Validate frame pointer */
  46                 low = sp;
  47                 high = ALIGN(sp, THREAD_SIZE);
  48                 if (unlikely(fp < low || fp > high || fp & 0x3))
  49                         break;
  50                 /* Unwind stack frame */
  51                 frame = (struct stackframe *)fp;
  52                 sp = fp;
  53                 fp = frame->fp;
  54                 pc = ftrace_graph_ret_addr(current, NULL, frame->ra,
  55                                            (unsigned long *)(fp - 8));
  56         }
  57 }
  58
  59 #else /* !CONFIG_FRAME_POINTER */
  60
  61 static void notrace walk_stackframe(struct task_struct *task,
  62         struct pt_regs *regs, bool (*fn)(unsigned long, void *), void *arg)
  63 {
  64         unsigned long sp, pc;
  65         unsigned long *ksp;
  66
  67         if (regs) {
  68                 sp = user_stack_pointer(regs);
  69                 pc = instruction_pointer(regs);
  70         } else if (task == NULL || task == current) {
  71                 const register unsigned long current_sp __asm__ ("sp");
  72                 sp = current_sp;
  73                 pc = (unsigned long)walk_stackframe;
  74         } else {
  75                 /* task blocked in __switch_to */
  76                 sp = thread_saved_sp(task);
  77                 pc = thread_saved_lr(task);
  78         }
  79
  80         if (unlikely(sp & 0x3))
  81                 return;
  82
  83         ksp = (unsigned long *)sp;
  84         while (!kstack_end(ksp)) {
  85                 if (__kernel_text_address(pc) && unlikely(fn(pc, arg)))
  86                         break;
  87                 pc = (*ksp++) - 0x4;
  88         }
  89 }
  90 #endif /* CONFIG_FRAME_POINTER */
  91
  92 static bool print_trace_address(unsigned long pc, void *arg)
  93 {
  94         print_ip_sym((const char *)arg, pc);
  95         return false;
  96 }
  97
  98 void show_stack(struct task_struct *task, unsigned long *sp, const char *loglvl)
  99 {
 100         pr_cont("Call Trace:\n");
 101         walk_stackframe(task, NULL, print_trace_address, (void *)loglvl);
 102 }
 103
 104 static bool save_wchan(unsigned long pc, void *arg)
 105 {
 106         if (!in_sched_functions(pc)) {
 107                 unsigned long *p = arg;
 108                 *p = pc;
 109                 return true;
 110         }
 111         return false;
 112 }
 113
 114 unsigned long get_wchan(struct task_struct *task)
 115 {
 116         unsigned long pc = 0;
 117
 118         if (likely(task && task != current && task->state != TASK_RUNNING))
 119                 walk_stackframe(task, NULL, save_wchan, &pc);
 120         return pc;
 121 }
 122
 123 #ifdef CONFIG_STACKTRACE
 124 static bool __save_trace(unsigned long pc, void *arg, bool nosched)
 125 {
 126         struct stack_trace *trace = arg;
 127
 128         if (unlikely(nosched && in_sched_functions(pc)))
 129                 return false;
 130         if (unlikely(trace->skip > 0)) {
 131                 trace->skip--;
 132                 return false;
 133         }
 134
 135         trace->entries[trace->nr_entries++] = pc;
 136         return (trace->nr_entries >= trace->max_entries);
 137 }
 138
 139 static bool save_trace(unsigned long pc, void *arg)
 140 {
 141         return __save_trace(pc, arg, false);
 142 }
 143
 144 /*
 145  * Save stack-backtrace addresses into a stack_trace buffer.
 146  */
 147 void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
 148 {
 149         walk_stackframe(tsk, NULL, save_trace, trace);
 150 }
 151 EXPORT_SYMBOL_GPL(save_stack_trace_tsk);
 152
 153 void save_stack_trace(struct stack_trace *trace)
 154 {
 155         save_stack_trace_tsk(NULL, trace);
 156 }
 157 EXPORT_SYMBOL_GPL(save_stack_trace);
 158
 159 #endif /* CONFIG_STACKTRACE */