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f73670e8 G |
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/stacktrace.h> | |
15 | ||
16 | #include <asm/stacktrace.h> | |
17 | ||
18 | #if defined(CONFIG_FRAME_POINTER) | |
19 | /* | |
20 | * Unwind the current stack frame and store the new register values in the | |
21 | * structure passed as argument. Unwinding is equivalent to a function return, | |
22 | * hence the new PC value rather than LR should be used for backtrace. | |
23 | * | |
24 | * With framepointer enabled, a simple function prologue looks like this: | |
25 | * mov ip, sp | |
26 | * stmdb sp!, {fp, ip, lr, pc} | |
27 | * sub fp, ip, #4 | |
28 | * | |
29 | * A simple function epilogue looks like this: | |
30 | * ldm sp, {fp, sp, pc} | |
31 | * | |
32 | * Note that with framepointer enabled, even the leaf functions have the same | |
33 | * prologue and epilogue, therefore we can ignore the LR value in this case. | |
34 | */ | |
35 | int notrace unwind_frame(struct stackframe *frame) | |
36 | { | |
37 | unsigned long high, low; | |
38 | unsigned long fp = frame->fp; | |
39 | ||
40 | /* only go to a higher address on the stack */ | |
41 | low = frame->sp; | |
42 | high = ALIGN(low, THREAD_SIZE); | |
43 | ||
44 | /* check current frame pointer is within bounds */ | |
45 | if (fp < (low + 12) || fp + 4 >= high) | |
46 | return -EINVAL; | |
47 | ||
48 | /* restore the registers from the stack frame */ | |
49 | frame->fp = *(unsigned long *)(fp - 12); | |
50 | frame->sp = *(unsigned long *)(fp - 8); | |
51 | frame->pc = *(unsigned long *)(fp - 4); | |
52 | ||
53 | return 0; | |
54 | } | |
55 | #endif | |
56 | ||
57 | void notrace walk_stackframe(struct stackframe *frame, | |
58 | int (*fn)(struct stackframe *, void *), void *data) | |
59 | { | |
60 | while (1) { | |
61 | int ret; | |
62 | ||
63 | if (fn(frame, data)) | |
64 | break; | |
65 | ret = unwind_frame(frame); | |
66 | if (ret < 0) | |
67 | break; | |
68 | } | |
69 | } | |
70 | EXPORT_SYMBOL(walk_stackframe); | |
71 | ||
72 | #ifdef CONFIG_STACKTRACE | |
73 | struct stack_trace_data { | |
74 | struct stack_trace *trace; | |
75 | unsigned int no_sched_functions; | |
76 | unsigned int skip; | |
77 | }; | |
78 | ||
79 | static int save_trace(struct stackframe *frame, void *d) | |
80 | { | |
81 | struct stack_trace_data *data = d; | |
82 | struct stack_trace *trace = data->trace; | |
83 | unsigned long addr = frame->pc; | |
84 | ||
85 | if (data->no_sched_functions && in_sched_functions(addr)) | |
86 | return 0; | |
87 | if (data->skip) { | |
88 | data->skip--; | |
89 | return 0; | |
90 | } | |
91 | ||
92 | trace->entries[trace->nr_entries++] = addr; | |
93 | ||
94 | return trace->nr_entries >= trace->max_entries; | |
95 | } | |
96 | ||
97 | void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace) | |
98 | { | |
99 | struct stack_trace_data data; | |
100 | struct stackframe frame; | |
101 | ||
102 | data.trace = trace; | |
103 | data.skip = trace->skip; | |
104 | ||
105 | if (tsk != current) { | |
106 | data.no_sched_functions = 1; | |
107 | frame.fp = thread_saved_fp(tsk); | |
108 | frame.sp = thread_saved_sp(tsk); | |
109 | frame.lr = 0; /* recovered from the stack */ | |
110 | frame.pc = thread_saved_pc(tsk); | |
111 | } else { | |
112 | register unsigned long current_sp asm("sp"); | |
113 | ||
114 | data.no_sched_functions = 0; | |
115 | frame.fp = (unsigned long)__builtin_frame_address(0); | |
116 | frame.sp = current_sp; | |
117 | frame.lr = (unsigned long)__builtin_return_address(0); | |
118 | frame.pc = (unsigned long)save_stack_trace_tsk; | |
119 | } | |
120 | ||
121 | walk_stackframe(&frame, save_trace, &data); | |
122 | if (trace->nr_entries < trace->max_entries) | |
123 | trace->entries[trace->nr_entries++] = ULONG_MAX; | |
124 | } | |
125 | ||
126 | void save_stack_trace(struct stack_trace *trace) | |
127 | { | |
128 | save_stack_trace_tsk(current, trace); | |
129 | } | |
130 | EXPORT_SYMBOL_GPL(save_stack_trace); | |
131 | #endif |