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1#include <linux/module.h>
2#include <linux/sched.h>
3#include <linux/stacktrace.h>
4
5#include <asm/stacktrace.h>
6
7#if defined(CONFIG_FRAME_POINTER) && !defined(CONFIG_ARM_UNWIND)
8/*
9 * Unwind the current stack frame and store the new register values in the
10 * structure passed as argument. Unwinding is equivalent to a function return,
11 * hence the new PC value rather than LR should be used for backtrace.
12 *
13 * With framepointer enabled, a simple function prologue looks like this:
14 * mov ip, sp
15 * stmdb sp!, {fp, ip, lr, pc}
16 * sub fp, ip, #4
17 *
18 * A simple function epilogue looks like this:
19 * ldm sp, {fp, sp, pc}
20 *
21 * Note that with framepointer enabled, even the leaf functions have the same
22 * prologue and epilogue, therefore we can ignore the LR value in this case.
23 */
24int notrace unwind_frame(struct stackframe *frame)
25{
26 unsigned long high, low;
27 unsigned long fp = frame->fp;
28
29 /* only go to a higher address on the stack */
30 low = frame->sp;
31 high = ALIGN(low, THREAD_SIZE);
32
33 /* check current frame pointer is within bounds */
34 if (fp < (low + 12) || fp + 4 >= high)
35 return -EINVAL;
36
37 /* restore the registers from the stack frame */
38 frame->fp = *(unsigned long *)(fp - 12);
39 frame->sp = *(unsigned long *)(fp - 8);
40 frame->pc = *(unsigned long *)(fp - 4);
41
42 return 0;
43}
44#endif
45
46void notrace walk_stackframe(struct stackframe *frame,
47 int (*fn)(struct stackframe *, void *), void *data)
48{
49 while (1) {
50 int ret;
51
52 if (fn(frame, data))
53 break;
54 ret = unwind_frame(frame);
55 if (ret < 0)
56 break;
57 }
58}
59EXPORT_SYMBOL(walk_stackframe);
60
61#ifdef CONFIG_STACKTRACE
62struct stack_trace_data {
63 struct stack_trace *trace;
64 unsigned int no_sched_functions;
65 unsigned int skip;
66};
67
68static int save_trace(struct stackframe *frame, void *d)
69{
70 struct stack_trace_data *data = d;
71 struct stack_trace *trace = data->trace;
72 unsigned long addr = frame->pc;
73
74 if (data->no_sched_functions && in_sched_functions(addr))
75 return 0;
76 if (data->skip) {
77 data->skip--;
78 return 0;
79 }
80
81 trace->entries[trace->nr_entries++] = addr;
82
83 return trace->nr_entries >= trace->max_entries;
84}
85
86void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
87{
88 struct stack_trace_data data;
89 struct stackframe frame;
90
91 data.trace = trace;
92 data.skip = trace->skip;
93
94 if (tsk != current) {
95#ifdef CONFIG_SMP
96 /*
97 * What guarantees do we have here that 'tsk' is not
98 * running on another CPU? For now, ignore it as we
99 * can't guarantee we won't explode.
100 */
101 if (trace->nr_entries < trace->max_entries)
102 trace->entries[trace->nr_entries++] = ULONG_MAX;
103 return;
104#else
105 data.no_sched_functions = 1;
106 frame.fp = thread_saved_fp(tsk);
107 frame.sp = thread_saved_sp(tsk);
108 frame.lr = 0; /* recovered from the stack */
109 frame.pc = thread_saved_pc(tsk);
110#endif
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
126void save_stack_trace(struct stack_trace *trace)
127{
128 save_stack_trace_tsk(current, trace);
129}
130EXPORT_SYMBOL_GPL(save_stack_trace);
131#endif
1#include <linux/export.h>
2#include <linux/sched.h>
3#include <linux/stacktrace.h>
4
5#include <asm/stacktrace.h>
6#include <asm/traps.h>
7
8#if defined(CONFIG_FRAME_POINTER) && !defined(CONFIG_ARM_UNWIND)
9/*
10 * Unwind the current stack frame and store the new register values in the
11 * structure passed as argument. Unwinding is equivalent to a function return,
12 * hence the new PC value rather than LR should be used for backtrace.
13 *
14 * With framepointer enabled, a simple function prologue looks like this:
15 * mov ip, sp
16 * stmdb sp!, {fp, ip, lr, pc}
17 * sub fp, ip, #4
18 *
19 * A simple function epilogue looks like this:
20 * ldm sp, {fp, sp, pc}
21 *
22 * Note that with framepointer enabled, even the leaf functions have the same
23 * prologue and epilogue, therefore we can ignore the LR value in this case.
24 */
25int notrace unwind_frame(struct stackframe *frame)
26{
27 unsigned long high, low;
28 unsigned long fp = frame->fp;
29
30 /* only go to a higher address on the stack */
31 low = frame->sp;
32 high = ALIGN(low, THREAD_SIZE);
33
34 /* check current frame pointer is within bounds */
35 if (fp < low + 12 || fp > high - 4)
36 return -EINVAL;
37
38 /* restore the registers from the stack frame */
39 frame->fp = *(unsigned long *)(fp - 12);
40 frame->sp = *(unsigned long *)(fp - 8);
41 frame->pc = *(unsigned long *)(fp - 4);
42
43 return 0;
44}
45#endif
46
47void notrace walk_stackframe(struct stackframe *frame,
48 int (*fn)(struct stackframe *, void *), void *data)
49{
50 while (1) {
51 int ret;
52
53 if (fn(frame, data))
54 break;
55 ret = unwind_frame(frame);
56 if (ret < 0)
57 break;
58 }
59}
60EXPORT_SYMBOL(walk_stackframe);
61
62#ifdef CONFIG_STACKTRACE
63struct stack_trace_data {
64 struct stack_trace *trace;
65 unsigned long last_pc;
66 unsigned int no_sched_functions;
67 unsigned int skip;
68};
69
70static int save_trace(struct stackframe *frame, void *d)
71{
72 struct stack_trace_data *data = d;
73 struct stack_trace *trace = data->trace;
74 struct pt_regs *regs;
75 unsigned long addr = frame->pc;
76
77 if (data->no_sched_functions && in_sched_functions(addr))
78 return 0;
79 if (data->skip) {
80 data->skip--;
81 return 0;
82 }
83
84 trace->entries[trace->nr_entries++] = addr;
85
86 if (trace->nr_entries >= trace->max_entries)
87 return 1;
88
89 /*
90 * in_exception_text() is designed to test if the PC is one of
91 * the functions which has an exception stack above it, but
92 * unfortunately what is in frame->pc is the return LR value,
93 * not the saved PC value. So, we need to track the previous
94 * frame PC value when doing this.
95 */
96 addr = data->last_pc;
97 data->last_pc = frame->pc;
98 if (!in_exception_text(addr))
99 return 0;
100
101 regs = (struct pt_regs *)frame->sp;
102
103 trace->entries[trace->nr_entries++] = regs->ARM_pc;
104
105 return trace->nr_entries >= trace->max_entries;
106}
107
108/* This must be noinline to so that our skip calculation works correctly */
109static noinline void __save_stack_trace(struct task_struct *tsk,
110 struct stack_trace *trace, unsigned int nosched)
111{
112 struct stack_trace_data data;
113 struct stackframe frame;
114
115 data.trace = trace;
116 data.last_pc = ULONG_MAX;
117 data.skip = trace->skip;
118 data.no_sched_functions = nosched;
119
120 if (tsk != current) {
121#ifdef CONFIG_SMP
122 /*
123 * What guarantees do we have here that 'tsk' is not
124 * running on another CPU? For now, ignore it as we
125 * can't guarantee we won't explode.
126 */
127 if (trace->nr_entries < trace->max_entries)
128 trace->entries[trace->nr_entries++] = ULONG_MAX;
129 return;
130#else
131 frame.fp = thread_saved_fp(tsk);
132 frame.sp = thread_saved_sp(tsk);
133 frame.lr = 0; /* recovered from the stack */
134 frame.pc = thread_saved_pc(tsk);
135#endif
136 } else {
137 /* We don't want this function nor the caller */
138 data.skip += 2;
139 frame.fp = (unsigned long)__builtin_frame_address(0);
140 frame.sp = current_stack_pointer;
141 frame.lr = (unsigned long)__builtin_return_address(0);
142 frame.pc = (unsigned long)__save_stack_trace;
143 }
144
145 walk_stackframe(&frame, save_trace, &data);
146 if (trace->nr_entries < trace->max_entries)
147 trace->entries[trace->nr_entries++] = ULONG_MAX;
148}
149
150void save_stack_trace_regs(struct pt_regs *regs, struct stack_trace *trace)
151{
152 struct stack_trace_data data;
153 struct stackframe frame;
154
155 data.trace = trace;
156 data.skip = trace->skip;
157 data.no_sched_functions = 0;
158
159 frame.fp = regs->ARM_fp;
160 frame.sp = regs->ARM_sp;
161 frame.lr = regs->ARM_lr;
162 frame.pc = regs->ARM_pc;
163
164 walk_stackframe(&frame, save_trace, &data);
165 if (trace->nr_entries < trace->max_entries)
166 trace->entries[trace->nr_entries++] = ULONG_MAX;
167}
168
169void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
170{
171 __save_stack_trace(tsk, trace, 1);
172}
173
174void save_stack_trace(struct stack_trace *trace)
175{
176 __save_stack_trace(current, trace, 0);
177}
178EXPORT_SYMBOL_GPL(save_stack_trace);
179#endif