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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