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60ffc30d CM |
1 | /* |
2 | * Stack tracing support | |
3 | * | |
4 | * Copyright (C) 2012 ARM Ltd. | |
5 | * | |
6 | * This program is free software; you can redistribute it and/or modify | |
7 | * it under the terms of the GNU General Public License version 2 as | |
8 | * published by the Free Software Foundation. | |
9 | * | |
10 | * This program is distributed in the hope that it will be useful, | |
11 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
12 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
13 | * GNU General Public License for more details. | |
14 | * | |
15 | * You should have received a copy of the GNU General Public License | |
16 | * along with this program. If not, see <http://www.gnu.org/licenses/>. | |
17 | */ | |
18 | #include <linux/kernel.h> | |
19 | #include <linux/export.h> | |
20 | #include <linux/sched.h> | |
21 | #include <linux/stacktrace.h> | |
22 | ||
23 | #include <asm/stacktrace.h> | |
24 | ||
25 | /* | |
26 | * AArch64 PCS assigns the frame pointer to x29. | |
27 | * | |
28 | * A simple function prologue looks like this: | |
29 | * sub sp, sp, #0x10 | |
30 | * stp x29, x30, [sp] | |
31 | * mov x29, sp | |
32 | * | |
33 | * A simple function epilogue looks like this: | |
34 | * mov sp, x29 | |
35 | * ldp x29, x30, [sp] | |
36 | * add sp, sp, #0x10 | |
37 | */ | |
26e2ae39 | 38 | int notrace unwind_frame(struct stackframe *frame) |
60ffc30d CM |
39 | { |
40 | unsigned long high, low; | |
41 | unsigned long fp = frame->fp; | |
42 | ||
43 | low = frame->sp; | |
44 | high = ALIGN(low, THREAD_SIZE); | |
45 | ||
26920dd2 | 46 | if (fp < low || fp > high - 0x18 || fp & 0xf) |
60ffc30d CM |
47 | return -EINVAL; |
48 | ||
49 | frame->sp = fp + 0x10; | |
50 | frame->fp = *(unsigned long *)(fp); | |
e306dfd0 OJ |
51 | /* |
52 | * -4 here because we care about the PC at time of bl, | |
53 | * not where the return will go. | |
54 | */ | |
55 | frame->pc = *(unsigned long *)(fp + 8) - 4; | |
60ffc30d CM |
56 | |
57 | return 0; | |
58 | } | |
59 | ||
60 | void notrace walk_stackframe(struct stackframe *frame, | |
61 | int (*fn)(struct stackframe *, void *), void *data) | |
62 | { | |
63 | while (1) { | |
64 | int ret; | |
65 | ||
66 | if (fn(frame, data)) | |
67 | break; | |
68 | ret = unwind_frame(frame); | |
69 | if (ret < 0) | |
70 | break; | |
71 | } | |
72 | } | |
73 | EXPORT_SYMBOL(walk_stackframe); | |
74 | ||
75 | #ifdef CONFIG_STACKTRACE | |
76 | struct stack_trace_data { | |
77 | struct stack_trace *trace; | |
78 | unsigned int no_sched_functions; | |
79 | unsigned int skip; | |
80 | }; | |
81 | ||
82 | static int save_trace(struct stackframe *frame, void *d) | |
83 | { | |
84 | struct stack_trace_data *data = d; | |
85 | struct stack_trace *trace = data->trace; | |
86 | unsigned long addr = frame->pc; | |
87 | ||
88 | if (data->no_sched_functions && in_sched_functions(addr)) | |
89 | return 0; | |
90 | if (data->skip) { | |
91 | data->skip--; | |
92 | return 0; | |
93 | } | |
94 | ||
95 | trace->entries[trace->nr_entries++] = addr; | |
96 | ||
97 | return trace->nr_entries >= trace->max_entries; | |
98 | } | |
99 | ||
100 | void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace) | |
101 | { | |
102 | struct stack_trace_data data; | |
103 | struct stackframe frame; | |
104 | ||
105 | data.trace = trace; | |
106 | data.skip = trace->skip; | |
107 | ||
108 | if (tsk != current) { | |
109 | data.no_sched_functions = 1; | |
110 | frame.fp = thread_saved_fp(tsk); | |
111 | frame.sp = thread_saved_sp(tsk); | |
112 | frame.pc = thread_saved_pc(tsk); | |
113 | } else { | |
60ffc30d CM |
114 | data.no_sched_functions = 0; |
115 | frame.fp = (unsigned long)__builtin_frame_address(0); | |
bb28cec4 | 116 | frame.sp = current_stack_pointer; |
60ffc30d CM |
117 | frame.pc = (unsigned long)save_stack_trace_tsk; |
118 | } | |
119 | ||
120 | walk_stackframe(&frame, save_trace, &data); | |
121 | if (trace->nr_entries < trace->max_entries) | |
122 | trace->entries[trace->nr_entries++] = ULONG_MAX; | |
123 | } | |
124 | ||
125 | void save_stack_trace(struct stack_trace *trace) | |
126 | { | |
127 | save_stack_trace_tsk(current, trace); | |
128 | } | |
129 | EXPORT_SYMBOL_GPL(save_stack_trace); | |
130 | #endif |