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457c8996 | 1 | // SPDX-License-Identifier: GPL-2.0-only |
ecea4ab6 | 2 | #include <linux/export.h> |
f16fb1ec | 3 | #include <linux/sched.h> |
b17b0153 | 4 | #include <linux/sched/debug.h> |
f16fb1ec RK |
5 | #include <linux/stacktrace.h> |
6 | ||
c6089061 | 7 | #include <asm/sections.h> |
2d7c11bf | 8 | #include <asm/stacktrace.h> |
07b40341 | 9 | #include <asm/traps.h> |
2d7c11bf CM |
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 | * | |
b4d5ec9b NH |
25 | * When compiled with clang, pc and sp are not pushed. A simple function |
26 | * prologue looks like this when built with clang: | |
27 | * | |
28 | * stmdb {..., fp, lr} | |
29 | * add fp, sp, #x | |
30 | * sub sp, sp, #y | |
31 | * | |
32 | * A simple function epilogue looks like this when built with clang: | |
33 | * | |
34 | * sub sp, fp, #x | |
35 | * ldm {..., fp, pc} | |
36 | * | |
37 | * | |
2d7c11bf CM |
38 | * Note that with framepointer enabled, even the leaf functions have the same |
39 | * prologue and epilogue, therefore we can ignore the LR value in this case. | |
40 | */ | |
4bf1fa5a | 41 | int notrace unwind_frame(struct stackframe *frame) |
f16fb1ec | 42 | { |
2d7c11bf CM |
43 | unsigned long high, low; |
44 | unsigned long fp = frame->fp; | |
f16fb1ec | 45 | |
2d7c11bf CM |
46 | /* only go to a higher address on the stack */ |
47 | low = frame->sp; | |
d33aadbf | 48 | high = ALIGN(low, THREAD_SIZE); |
f16fb1ec | 49 | |
b4d5ec9b NH |
50 | #ifdef CONFIG_CC_IS_CLANG |
51 | /* check current frame pointer is within bounds */ | |
52 | if (fp < low + 4 || fp > high - 4) | |
53 | return -EINVAL; | |
54 | ||
55 | frame->sp = frame->fp; | |
56 | frame->fp = *(unsigned long *)(fp); | |
57 | frame->pc = frame->lr; | |
58 | frame->lr = *(unsigned long *)(fp + 4); | |
59 | #else | |
2d7c11bf | 60 | /* check current frame pointer is within bounds */ |
3abb6671 | 61 | if (fp < low + 12 || fp > high - 4) |
2d7c11bf | 62 | return -EINVAL; |
f16fb1ec | 63 | |
2d7c11bf CM |
64 | /* restore the registers from the stack frame */ |
65 | frame->fp = *(unsigned long *)(fp - 12); | |
66 | frame->sp = *(unsigned long *)(fp - 8); | |
67 | frame->pc = *(unsigned long *)(fp - 4); | |
b4d5ec9b | 68 | #endif |
f16fb1ec RK |
69 | |
70 | return 0; | |
71 | } | |
2d7c11bf CM |
72 | #endif |
73 | ||
4bf1fa5a | 74 | void notrace walk_stackframe(struct stackframe *frame, |
2d7c11bf CM |
75 | int (*fn)(struct stackframe *, void *), void *data) |
76 | { | |
77 | while (1) { | |
78 | int ret; | |
79 | ||
80 | if (fn(frame, data)) | |
81 | break; | |
82 | ret = unwind_frame(frame); | |
83 | if (ret < 0) | |
84 | break; | |
85 | } | |
86 | } | |
7b104bcb | 87 | EXPORT_SYMBOL(walk_stackframe); |
f16fb1ec RK |
88 | |
89 | #ifdef CONFIG_STACKTRACE | |
90 | struct stack_trace_data { | |
91 | struct stack_trace *trace; | |
f76e9154 | 92 | unsigned int no_sched_functions; |
f16fb1ec RK |
93 | unsigned int skip; |
94 | }; | |
95 | ||
96 | static int save_trace(struct stackframe *frame, void *d) | |
97 | { | |
98 | struct stack_trace_data *data = d; | |
99 | struct stack_trace *trace = data->trace; | |
07b40341 | 100 | struct pt_regs *regs; |
2d7c11bf | 101 | unsigned long addr = frame->pc; |
f16fb1ec | 102 | |
f76e9154 NP |
103 | if (data->no_sched_functions && in_sched_functions(addr)) |
104 | return 0; | |
f16fb1ec RK |
105 | if (data->skip) { |
106 | data->skip--; | |
107 | return 0; | |
108 | } | |
109 | ||
f76e9154 | 110 | trace->entries[trace->nr_entries++] = addr; |
f16fb1ec | 111 | |
07b40341 RK |
112 | if (trace->nr_entries >= trace->max_entries) |
113 | return 1; | |
114 | ||
c6089061 | 115 | if (!in_entry_text(frame->pc)) |
07b40341 RK |
116 | return 0; |
117 | ||
118 | regs = (struct pt_regs *)frame->sp; | |
40ff1ddb VW |
119 | if ((unsigned long)®s[1] > ALIGN(frame->sp, THREAD_SIZE)) |
120 | return 0; | |
07b40341 RK |
121 | |
122 | trace->entries[trace->nr_entries++] = regs->ARM_pc; | |
123 | ||
f16fb1ec RK |
124 | return trace->nr_entries >= trace->max_entries; |
125 | } | |
126 | ||
3683f44c RK |
127 | /* This must be noinline to so that our skip calculation works correctly */ |
128 | static noinline void __save_stack_trace(struct task_struct *tsk, | |
129 | struct stack_trace *trace, unsigned int nosched) | |
f16fb1ec RK |
130 | { |
131 | struct stack_trace_data data; | |
2d7c11bf | 132 | struct stackframe frame; |
f16fb1ec RK |
133 | |
134 | data.trace = trace; | |
135 | data.skip = trace->skip; | |
3683f44c | 136 | data.no_sched_functions = nosched; |
f76e9154 NP |
137 | |
138 | if (tsk != current) { | |
139 | #ifdef CONFIG_SMP | |
140 | /* | |
d5996b2f RK |
141 | * What guarantees do we have here that 'tsk' is not |
142 | * running on another CPU? For now, ignore it as we | |
143 | * can't guarantee we won't explode. | |
f76e9154 | 144 | */ |
d5996b2f | 145 | return; |
f76e9154 | 146 | #else |
2d7c11bf CM |
147 | frame.fp = thread_saved_fp(tsk); |
148 | frame.sp = thread_saved_sp(tsk); | |
149 | frame.lr = 0; /* recovered from the stack */ | |
150 | frame.pc = thread_saved_pc(tsk); | |
f76e9154 NP |
151 | #endif |
152 | } else { | |
3683f44c RK |
153 | /* We don't want this function nor the caller */ |
154 | data.skip += 2; | |
2d7c11bf | 155 | frame.fp = (unsigned long)__builtin_frame_address(0); |
74dbeee0 | 156 | frame.sp = current_stack_pointer; |
2d7c11bf | 157 | frame.lr = (unsigned long)__builtin_return_address(0); |
3683f44c | 158 | frame.pc = (unsigned long)__save_stack_trace; |
f76e9154 | 159 | } |
f16fb1ec | 160 | |
2d7c11bf | 161 | walk_stackframe(&frame, save_trace, &data); |
f76e9154 NP |
162 | } |
163 | ||
9c986661 LY |
164 | void save_stack_trace_regs(struct pt_regs *regs, struct stack_trace *trace) |
165 | { | |
166 | struct stack_trace_data data; | |
167 | struct stackframe frame; | |
168 | ||
169 | data.trace = trace; | |
170 | data.skip = trace->skip; | |
171 | data.no_sched_functions = 0; | |
172 | ||
173 | frame.fp = regs->ARM_fp; | |
174 | frame.sp = regs->ARM_sp; | |
175 | frame.lr = regs->ARM_lr; | |
176 | frame.pc = regs->ARM_pc; | |
177 | ||
178 | walk_stackframe(&frame, save_trace, &data); | |
9c986661 LY |
179 | } |
180 | ||
3683f44c RK |
181 | void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace) |
182 | { | |
183 | __save_stack_trace(tsk, trace, 1); | |
184 | } | |
9a3dc318 | 185 | EXPORT_SYMBOL(save_stack_trace_tsk); |
3683f44c | 186 | |
f76e9154 NP |
187 | void save_stack_trace(struct stack_trace *trace) |
188 | { | |
3683f44c | 189 | __save_stack_trace(current, trace, 0); |
f16fb1ec | 190 | } |
7b4c9505 | 191 | EXPORT_SYMBOL_GPL(save_stack_trace); |
f16fb1ec | 192 | #endif |