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1#include <linux/export.h>
2#include <linux/sched.h>
3#include <linux/sched/debug.h>
4#include <linux/stacktrace.h>
5
6#include <asm/sections.h>
7#include <asm/stacktrace.h>
8#include <asm/traps.h>
9
10#if defined(CONFIG_FRAME_POINTER) && !defined(CONFIG_ARM_UNWIND)
11/*
12 * Unwind the current stack frame and store the new register values in the
13 * structure passed as argument. Unwinding is equivalent to a function return,
14 * hence the new PC value rather than LR should be used for backtrace.
15 *
16 * With framepointer enabled, a simple function prologue looks like this:
17 * mov ip, sp
18 * stmdb sp!, {fp, ip, lr, pc}
19 * sub fp, ip, #4
20 *
21 * A simple function epilogue looks like this:
22 * ldm sp, {fp, sp, pc}
23 *
24 * Note that with framepointer enabled, even the leaf functions have the same
25 * prologue and epilogue, therefore we can ignore the LR value in this case.
26 */
27int notrace unwind_frame(struct stackframe *frame)
28{
29 unsigned long high, low;
30 unsigned long fp = frame->fp;
31
32 /* only go to a higher address on the stack */
33 low = frame->sp;
34 high = ALIGN(low, THREAD_SIZE);
35
36 /* check current frame pointer is within bounds */
37 if (fp < low + 12 || fp > high - 4)
38 return -EINVAL;
39
40 /* restore the registers from the stack frame */
41 frame->fp = *(unsigned long *)(fp - 12);
42 frame->sp = *(unsigned long *)(fp - 8);
43 frame->pc = *(unsigned long *)(fp - 4);
44
45 return 0;
46}
47#endif
48
49void notrace walk_stackframe(struct stackframe *frame,
50 int (*fn)(struct stackframe *, void *), void *data)
51{
52 while (1) {
53 int ret;
54
55 if (fn(frame, data))
56 break;
57 ret = unwind_frame(frame);
58 if (ret < 0)
59 break;
60 }
61}
62EXPORT_SYMBOL(walk_stackframe);
63
64#ifdef CONFIG_STACKTRACE
65struct stack_trace_data {
66 struct stack_trace *trace;
67 unsigned int no_sched_functions;
68 unsigned int skip;
69};
70
71static int save_trace(struct stackframe *frame, void *d)
72{
73 struct stack_trace_data *data = d;
74 struct stack_trace *trace = data->trace;
75 struct pt_regs *regs;
76 unsigned long addr = frame->pc;
77
78 if (data->no_sched_functions && in_sched_functions(addr))
79 return 0;
80 if (data->skip) {
81 data->skip--;
82 return 0;
83 }
84
85 trace->entries[trace->nr_entries++] = addr;
86
87 if (trace->nr_entries >= trace->max_entries)
88 return 1;
89
90 if (!in_entry_text(frame->pc))
91 return 0;
92
93 regs = (struct pt_regs *)frame->sp;
94
95 trace->entries[trace->nr_entries++] = regs->ARM_pc;
96
97 return trace->nr_entries >= trace->max_entries;
98}
99
100/* This must be noinline to so that our skip calculation works correctly */
101static noinline void __save_stack_trace(struct task_struct *tsk,
102 struct stack_trace *trace, unsigned int nosched)
103{
104 struct stack_trace_data data;
105 struct stackframe frame;
106
107 data.trace = trace;
108 data.skip = trace->skip;
109 data.no_sched_functions = nosched;
110
111 if (tsk != current) {
112#ifdef CONFIG_SMP
113 /*
114 * What guarantees do we have here that 'tsk' is not
115 * running on another CPU? For now, ignore it as we
116 * can't guarantee we won't explode.
117 */
118 if (trace->nr_entries < trace->max_entries)
119 trace->entries[trace->nr_entries++] = ULONG_MAX;
120 return;
121#else
122 frame.fp = thread_saved_fp(tsk);
123 frame.sp = thread_saved_sp(tsk);
124 frame.lr = 0; /* recovered from the stack */
125 frame.pc = thread_saved_pc(tsk);
126#endif
127 } else {
128 /* We don't want this function nor the caller */
129 data.skip += 2;
130 frame.fp = (unsigned long)__builtin_frame_address(0);
131 frame.sp = current_stack_pointer;
132 frame.lr = (unsigned long)__builtin_return_address(0);
133 frame.pc = (unsigned long)__save_stack_trace;
134 }
135
136 walk_stackframe(&frame, save_trace, &data);
137 if (trace->nr_entries < trace->max_entries)
138 trace->entries[trace->nr_entries++] = ULONG_MAX;
139}
140
141void save_stack_trace_regs(struct pt_regs *regs, struct stack_trace *trace)
142{
143 struct stack_trace_data data;
144 struct stackframe frame;
145
146 data.trace = trace;
147 data.skip = trace->skip;
148 data.no_sched_functions = 0;
149
150 frame.fp = regs->ARM_fp;
151 frame.sp = regs->ARM_sp;
152 frame.lr = regs->ARM_lr;
153 frame.pc = regs->ARM_pc;
154
155 walk_stackframe(&frame, save_trace, &data);
156 if (trace->nr_entries < trace->max_entries)
157 trace->entries[trace->nr_entries++] = ULONG_MAX;
158}
159
160void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
161{
162 __save_stack_trace(tsk, trace, 1);
163}
164EXPORT_SYMBOL(save_stack_trace_tsk);
165
166void save_stack_trace(struct stack_trace *trace)
167{
168 __save_stack_trace(current, trace, 0);
169}
170EXPORT_SYMBOL_GPL(save_stack_trace);
171#endif
1// SPDX-License-Identifier: GPL-2.0-only
2#include <linux/export.h>
3#include <linux/sched.h>
4#include <linux/sched/debug.h>
5#include <linux/stacktrace.h>
6
7#include <asm/sections.h>
8#include <asm/stacktrace.h>
9#include <asm/traps.h>
10
11#if defined(CONFIG_FRAME_POINTER) && !defined(CONFIG_ARM_UNWIND)
12/*
13 * Unwind the current stack frame and store the new register values in the
14 * structure passed as argument. Unwinding is equivalent to a function return,
15 * hence the new PC value rather than LR should be used for backtrace.
16 *
17 * With framepointer enabled, a simple function prologue looks like this:
18 * mov ip, sp
19 * stmdb sp!, {fp, ip, lr, pc}
20 * sub fp, ip, #4
21 *
22 * A simple function epilogue looks like this:
23 * ldm sp, {fp, sp, pc}
24 *
25 * Note that with framepointer enabled, even the leaf functions have the same
26 * prologue and epilogue, therefore we can ignore the LR value in this case.
27 */
28int notrace unwind_frame(struct stackframe *frame)
29{
30 unsigned long high, low;
31 unsigned long fp = frame->fp;
32
33 /* only go to a higher address on the stack */
34 low = frame->sp;
35 high = ALIGN(low, THREAD_SIZE);
36
37 /* check current frame pointer is within bounds */
38 if (fp < low + 12 || fp > high - 4)
39 return -EINVAL;
40
41 /* restore the registers from the stack frame */
42 frame->fp = *(unsigned long *)(fp - 12);
43 frame->sp = *(unsigned long *)(fp - 8);
44 frame->pc = *(unsigned long *)(fp - 4);
45
46 return 0;
47}
48#endif
49
50void notrace walk_stackframe(struct stackframe *frame,
51 int (*fn)(struct stackframe *, void *), void *data)
52{
53 while (1) {
54 int ret;
55
56 if (fn(frame, data))
57 break;
58 ret = unwind_frame(frame);
59 if (ret < 0)
60 break;
61 }
62}
63EXPORT_SYMBOL(walk_stackframe);
64
65#ifdef CONFIG_STACKTRACE
66struct stack_trace_data {
67 struct stack_trace *trace;
68 unsigned int no_sched_functions;
69 unsigned int skip;
70};
71
72static int save_trace(struct stackframe *frame, void *d)
73{
74 struct stack_trace_data *data = d;
75 struct stack_trace *trace = data->trace;
76 struct pt_regs *regs;
77 unsigned long addr = frame->pc;
78
79 if (data->no_sched_functions && in_sched_functions(addr))
80 return 0;
81 if (data->skip) {
82 data->skip--;
83 return 0;
84 }
85
86 trace->entries[trace->nr_entries++] = addr;
87
88 if (trace->nr_entries >= trace->max_entries)
89 return 1;
90
91 if (!in_entry_text(frame->pc))
92 return 0;
93
94 regs = (struct pt_regs *)frame->sp;
95
96 trace->entries[trace->nr_entries++] = regs->ARM_pc;
97
98 return trace->nr_entries >= trace->max_entries;
99}
100
101/* This must be noinline to so that our skip calculation works correctly */
102static noinline void __save_stack_trace(struct task_struct *tsk,
103 struct stack_trace *trace, unsigned int nosched)
104{
105 struct stack_trace_data data;
106 struct stackframe frame;
107
108 data.trace = trace;
109 data.skip = trace->skip;
110 data.no_sched_functions = nosched;
111
112 if (tsk != current) {
113#ifdef CONFIG_SMP
114 /*
115 * What guarantees do we have here that 'tsk' is not
116 * running on another CPU? For now, ignore it as we
117 * can't guarantee we won't explode.
118 */
119 return;
120#else
121 frame.fp = thread_saved_fp(tsk);
122 frame.sp = thread_saved_sp(tsk);
123 frame.lr = 0; /* recovered from the stack */
124 frame.pc = thread_saved_pc(tsk);
125#endif
126 } else {
127 /* We don't want this function nor the caller */
128 data.skip += 2;
129 frame.fp = (unsigned long)__builtin_frame_address(0);
130 frame.sp = current_stack_pointer;
131 frame.lr = (unsigned long)__builtin_return_address(0);
132 frame.pc = (unsigned long)__save_stack_trace;
133 }
134
135 walk_stackframe(&frame, save_trace, &data);
136}
137
138void save_stack_trace_regs(struct pt_regs *regs, struct stack_trace *trace)
139{
140 struct stack_trace_data data;
141 struct stackframe frame;
142
143 data.trace = trace;
144 data.skip = trace->skip;
145 data.no_sched_functions = 0;
146
147 frame.fp = regs->ARM_fp;
148 frame.sp = regs->ARM_sp;
149 frame.lr = regs->ARM_lr;
150 frame.pc = regs->ARM_pc;
151
152 walk_stackframe(&frame, save_trace, &data);
153}
154
155void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
156{
157 __save_stack_trace(tsk, trace, 1);
158}
159EXPORT_SYMBOL(save_stack_trace_tsk);
160
161void save_stack_trace(struct stack_trace *trace)
162{
163 __save_stack_trace(current, trace, 0);
164}
165EXPORT_SYMBOL_GPL(save_stack_trace);
166#endif