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  */
  33 int 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
  55 void 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 }
  68 EXPORT_SYMBOL(walk_stackframe);
  69
  70 #ifdef CONFIG_STACKTRACE
  71 struct stack_trace_data {
  72         struct stack_trace *trace;
  73         unsigned int no_sched_functions;
  74         unsigned int skip;
  75 };
  76
  77 static 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
  95 void 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
 122 void save_stack_trace(struct stack_trace *trace)
 123 {
 124         save_stack_trace_tsk(current, trace);
 125 }
 126 EXPORT_SYMBOL_GPL(save_stack_trace);
 127 #endif