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