LXR linux/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 */
  35int 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
  57void 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}
  70EXPORT_SYMBOL(walk_stackframe);
  71
  72#ifdef CONFIG_STACKTRACE
  73struct stack_trace_data {
  74        struct stack_trace *trace;
  75        unsigned int no_sched_functions;
  76        unsigned int skip;
  77};
  78
  79static 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
  97void 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
 126void save_stack_trace(struct stack_trace *trace)
 127{
 128        save_stack_trace_tsk(current, trace);
 129}
 130EXPORT_SYMBOL_GPL(save_stack_trace);
 131#endif
 132