arch/unicore32/kernel/stacktrace.c

   1 /*
   2  * linux/arch/unicore32/kernel/stacktrace.c
   3  *
   4  * Code specific to PKUnity SoC and UniCore ISA
   5  *
   6  * Copyright (C) 2001-2010 GUAN Xue-tao
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License version 2 as
  10  * published by the Free Software Foundation.
  11  */
  12 #include <linux/module.h>
  13 #include <linux/sched.h>
  14 #include <linux/sched/debug.h>
  15 #include <linux/stacktrace.h>
  16
  17 #include <asm/stacktrace.h>
  18
  19 #if defined(CONFIG_FRAME_POINTER)
  20 /*
  21  * Unwind the current stack frame and store the new register values in the
  22  * structure passed as argument. Unwinding is equivalent to a function return,
  23  * hence the new PC value rather than LR should be used for backtrace.
  24  *
  25  * With framepointer enabled, a simple function prologue looks like this:
  26  *      mov     ip, sp
  27  *      stmdb   sp!, {fp, ip, lr, pc}
  28  *      sub     fp, ip, #4
  29  *
  30  * A simple function epilogue looks like this:
  31  *      ldm     sp, {fp, sp, pc}
  32  *
  33  * Note that with framepointer enabled, even the leaf functions have the same
  34  * prologue and epilogue, therefore we can ignore the LR value in this case.
  35  */
  36 int notrace unwind_frame(struct stackframe *frame)
  37 {
  38         unsigned long high, low;
  39         unsigned long fp = frame->fp;
  40
  41         /* only go to a higher address on the stack */
  42         low = frame->sp;
  43         high = ALIGN(low, THREAD_SIZE);
  44
  45         /* check current frame pointer is within bounds */
  46         if (fp < (low + 12) || fp + 4 >= high)
  47                 return -EINVAL;
  48
  49         /* restore the registers from the stack frame */
  50         frame->fp = *(unsigned long *)(fp - 12);
  51         frame->sp = *(unsigned long *)(fp - 8);
  52         frame->pc = *(unsigned long *)(fp - 4);
  53
  54         return 0;
  55 }
  56 #endif
  57
  58 void notrace walk_stackframe(struct stackframe *frame,
  59                      int (*fn)(struct stackframe *, void *), void *data)
  60 {
  61         while (1) {
  62                 int ret;
  63
  64                 if (fn(frame, data))
  65                         break;
  66                 ret = unwind_frame(frame);
  67                 if (ret < 0)
  68                         break;
  69         }
  70 }
  71 EXPORT_SYMBOL(walk_stackframe);
  72
  73 #ifdef CONFIG_STACKTRACE
  74 struct stack_trace_data {
  75         struct stack_trace *trace;
  76         unsigned int no_sched_functions;
  77         unsigned int skip;
  78 };
  79
  80 static int save_trace(struct stackframe *frame, void *d)
  81 {
  82         struct stack_trace_data *data = d;
  83         struct stack_trace *trace = data->trace;
  84         unsigned long addr = frame->pc;
  85
  86         if (data->no_sched_functions && in_sched_functions(addr))
  87                 return 0;
  88         if (data->skip) {
  89                 data->skip--;
  90                 return 0;
  91         }
  92
  93         trace->entries[trace->nr_entries++] = addr;
  94
  95         return trace->nr_entries >= trace->max_entries;
  96 }
  97
  98 void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
  99 {
 100         struct stack_trace_data data;
 101         struct stackframe frame;
 102
 103         data.trace = trace;
 104         data.skip = trace->skip;
 105
 106         if (tsk != current) {
 107                 data.no_sched_functions = 1;
 108                 frame.fp = thread_saved_fp(tsk);
 109                 frame.sp = thread_saved_sp(tsk);
 110                 frame.lr = 0;           /* recovered from the stack */
 111                 frame.pc = thread_saved_pc(tsk);
 112         } else {
 113                 register unsigned long current_sp asm("sp");
 114
 115                 data.no_sched_functions = 0;
 116                 frame.fp = (unsigned long)__builtin_frame_address(0);
 117                 frame.sp = current_sp;
 118                 frame.lr = (unsigned long)__builtin_return_address(0);
 119                 frame.pc = (unsigned long)save_stack_trace_tsk;
 120         }
 121
 122         walk_stackframe(&frame, save_trace, &data);
 123         if (trace->nr_entries < trace->max_entries)
 124                 trace->entries[trace->nr_entries++] = ULONG_MAX;
 125 }
 126
 127 void save_stack_trace(struct stack_trace *trace)
 128 {
 129         save_stack_trace_tsk(current, trace);
 130 }
 131 EXPORT_SYMBOL_GPL(save_stack_trace);
 132 #endif