LXR linux/arch/unicore32/kernel/stacktrace.c

   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * linux/arch/unicore32/kernel/stacktrace.c
   4 *
   5 * Code specific to PKUnity SoC and UniCore ISA
   6 *
   7 * Copyright (C) 2001-2010 GUAN Xue-tao
   8 */
   9#include <linux/module.h>
  10#include <linux/sched.h>
  11#include <linux/sched/debug.h>
  12#include <linux/stacktrace.h>
  13
  14#include <asm/stacktrace.h>
  15
  16#if defined(CONFIG_FRAME_POINTER)
  17/*
  18 * Unwind the current stack frame and store the new register values in the
  19 * structure passed as argument. Unwinding is equivalent to a function return,
  20 * hence the new PC value rather than LR should be used for backtrace.
  21 *
  22 * With framepointer enabled, a simple function prologue looks like this:
  23 *      mov     ip, sp
  24 *      stmdb   sp!, {fp, ip, lr, pc}
  25 *      sub     fp, ip, #4
  26 *
  27 * A simple function epilogue looks like this:
  28 *      ldm     sp, {fp, sp, pc}
  29 *
  30 * Note that with framepointer enabled, even the leaf functions have the same
  31 * prologue and epilogue, therefore we can ignore the LR value in this case.
  32 */
  33int notrace unwind_frame(struct stackframe *frame)
  34{
  35        unsigned long high, low;
  36        unsigned long fp = frame->fp;
  37
  38        /* only go to a higher address on the stack */
  39        low = frame->sp;
  40        high = ALIGN(low, THREAD_SIZE);
  41
  42        /* check current frame pointer is within bounds */
  43        if (fp < (low + 12) || fp + 4 >= high)
  44                return -EINVAL;
  45
  46        /* restore the registers from the stack frame */
  47        frame->fp = *(unsigned long *)(fp - 12);
  48        frame->sp = *(unsigned long *)(fp - 8);
  49        frame->pc = *(unsigned long *)(fp - 4);
  50
  51        return 0;
  52}
  53#endif
  54
  55void notrace walk_stackframe(struct stackframe *frame,
  56                     int (*fn)(struct stackframe *, void *), void *data)
  57{
  58        while (1) {
  59                int ret;
  60
  61                if (fn(frame, data))
  62                        break;
  63                ret = unwind_frame(frame);
  64                if (ret < 0)
  65                        break;
  66        }
  67}
  68EXPORT_SYMBOL(walk_stackframe);
  69
  70#ifdef CONFIG_STACKTRACE
  71struct stack_trace_data {
  72        struct stack_trace *trace;
  73        unsigned int no_sched_functions;
  74        unsigned int skip;
  75};
  76
  77static int save_trace(struct stackframe *frame, void *d)
  78{
  79        struct stack_trace_data *data = d;
  80        struct stack_trace *trace = data->trace;
  81        unsigned long addr = frame->pc;
  82
  83        if (data->no_sched_functions && in_sched_functions(addr))
  84                return 0;
  85        if (data->skip) {
  86                data->skip--;
  87                return 0;
  88        }
  89
  90        trace->entries[trace->nr_entries++] = addr;
  91
  92        return trace->nr_entries >= trace->max_entries;
  93}
  94
  95void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
  96{
  97        struct stack_trace_data data;
  98        struct stackframe frame;
  99
 100        data.trace = trace;
 101        data.skip = trace->skip;
 102
 103        if (tsk != current) {
 104                data.no_sched_functions = 1;
 105                frame.fp = thread_saved_fp(tsk);
 106                frame.sp = thread_saved_sp(tsk);
 107                frame.lr = 0;           /* recovered from the stack */
 108                frame.pc = thread_saved_pc(tsk);
 109        } else {
 110                register unsigned long current_sp asm("sp");
 111
 112                data.no_sched_functions = 0;
 113                frame.fp = (unsigned long)__builtin_frame_address(0);
 114                frame.sp = current_sp;
 115                frame.lr = (unsigned long)__builtin_return_address(0);
 116                frame.pc = (unsigned long)save_stack_trace_tsk;
 117        }
 118
 119        walk_stackframe(&frame, save_trace, &data);
 120}
 121
 122void save_stack_trace(struct stack_trace *trace)
 123{
 124        save_stack_trace_tsk(current, trace);
 125}
 126EXPORT_SYMBOL_GPL(save_stack_trace);
 127#endif
 128