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