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/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 */
  36int 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
  58void 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}
  71EXPORT_SYMBOL(walk_stackframe);
  72
  73#ifdef CONFIG_STACKTRACE
  74struct stack_trace_data {
  75        struct stack_trace *trace;
  76        unsigned int no_sched_functions;
  77        unsigned int skip;
  78};
  79
  80static 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
  98void 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
 127void save_stack_trace(struct stack_trace *trace)
 128{
 129        save_stack_trace_tsk(current, trace);
 130}
 131EXPORT_SYMBOL_GPL(save_stack_trace);
 132#endif
 133