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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> | |
20380bb3 | 20 | #include <linux/ftrace.h> |
60ffc30d CM |
21 | #include <linux/sched.h> |
22 | #include <linux/stacktrace.h> | |
23 | ||
132cd887 | 24 | #include <asm/irq.h> |
60ffc30d CM |
25 | #include <asm/stacktrace.h> |
26 | ||
27 | /* | |
28 | * AArch64 PCS assigns the frame pointer to x29. | |
29 | * | |
30 | * A simple function prologue looks like this: | |
31 | * sub sp, sp, #0x10 | |
32 | * stp x29, x30, [sp] | |
33 | * mov x29, sp | |
34 | * | |
35 | * A simple function epilogue looks like this: | |
36 | * mov sp, x29 | |
37 | * ldp x29, x30, [sp] | |
38 | * add sp, sp, #0x10 | |
39 | */ | |
fe13f95b | 40 | int notrace unwind_frame(struct task_struct *tsk, struct stackframe *frame) |
60ffc30d CM |
41 | { |
42 | unsigned long high, low; | |
43 | unsigned long fp = frame->fp; | |
132cd887 AT |
44 | unsigned long irq_stack_ptr; |
45 | ||
46 | /* | |
a80a0eb7 YS |
47 | * Switching between stacks is valid when tracing current and in |
48 | * non-preemptible context. | |
132cd887 | 49 | */ |
a80a0eb7 YS |
50 | if (tsk == current && !preemptible()) |
51 | irq_stack_ptr = IRQ_STACK_PTR(smp_processor_id()); | |
52 | else | |
53 | irq_stack_ptr = 0; | |
60ffc30d CM |
54 | |
55 | low = frame->sp; | |
132cd887 AT |
56 | /* irq stacks are not THREAD_SIZE aligned */ |
57 | if (on_irq_stack(frame->sp, raw_smp_processor_id())) | |
58 | high = irq_stack_ptr; | |
59 | else | |
60 | high = ALIGN(low, THREAD_SIZE) - 0x20; | |
60ffc30d | 61 | |
132cd887 | 62 | if (fp < low || fp > high || fp & 0xf) |
60ffc30d CM |
63 | return -EINVAL; |
64 | ||
65 | frame->sp = fp + 0x10; | |
bcaf669b YS |
66 | frame->fp = READ_ONCE_NOCHECK(*(unsigned long *)(fp)); |
67 | frame->pc = READ_ONCE_NOCHECK(*(unsigned long *)(fp + 8)); | |
60ffc30d | 68 | |
20380bb3 AT |
69 | #ifdef CONFIG_FUNCTION_GRAPH_TRACER |
70 | if (tsk && tsk->ret_stack && | |
71 | (frame->pc == (unsigned long)return_to_handler)) { | |
72 | /* | |
73 | * This is a case where function graph tracer has | |
74 | * modified a return address (LR) in a stack frame | |
75 | * to hook a function return. | |
76 | * So replace it to an original value. | |
77 | */ | |
78 | frame->pc = tsk->ret_stack[frame->graph--].ret; | |
79 | } | |
80 | #endif /* CONFIG_FUNCTION_GRAPH_TRACER */ | |
81 | ||
132cd887 AT |
82 | /* |
83 | * Check whether we are going to walk through from interrupt stack | |
84 | * to task stack. | |
85 | * If we reach the end of the stack - and its an interrupt stack, | |
971c67ce | 86 | * unpack the dummy frame to find the original elr. |
1ffe199b JM |
87 | * |
88 | * Check the frame->fp we read from the bottom of the irq_stack, | |
89 | * and the original task stack pointer are both in current->stack. | |
132cd887 | 90 | */ |
1ffe199b | 91 | if (frame->sp == irq_stack_ptr) { |
971c67ce | 92 | struct pt_regs *irq_args; |
1ffe199b JM |
93 | unsigned long orig_sp = IRQ_STACK_TO_TASK_STACK(irq_stack_ptr); |
94 | ||
971c67ce JM |
95 | if (object_is_on_stack((void *)orig_sp) && |
96 | object_is_on_stack((void *)frame->fp)) { | |
1ffe199b | 97 | frame->sp = orig_sp; |
971c67ce JM |
98 | |
99 | /* orig_sp is the saved pt_regs, find the elr */ | |
100 | irq_args = (struct pt_regs *)orig_sp; | |
101 | frame->pc = irq_args->pc; | |
102 | } else { | |
103 | /* | |
104 | * This frame has a non-standard format, and we | |
105 | * didn't fix it, because the data looked wrong. | |
106 | * Refuse to output this frame. | |
107 | */ | |
108 | return -EINVAL; | |
109 | } | |
1ffe199b | 110 | } |
132cd887 | 111 | |
60ffc30d CM |
112 | return 0; |
113 | } | |
114 | ||
fe13f95b | 115 | void notrace walk_stackframe(struct task_struct *tsk, struct stackframe *frame, |
60ffc30d CM |
116 | int (*fn)(struct stackframe *, void *), void *data) |
117 | { | |
118 | while (1) { | |
119 | int ret; | |
120 | ||
121 | if (fn(frame, data)) | |
122 | break; | |
fe13f95b | 123 | ret = unwind_frame(tsk, frame); |
60ffc30d CM |
124 | if (ret < 0) |
125 | break; | |
126 | } | |
127 | } | |
128 | EXPORT_SYMBOL(walk_stackframe); | |
129 | ||
130 | #ifdef CONFIG_STACKTRACE | |
131 | struct stack_trace_data { | |
132 | struct stack_trace *trace; | |
133 | unsigned int no_sched_functions; | |
134 | unsigned int skip; | |
135 | }; | |
136 | ||
137 | static int save_trace(struct stackframe *frame, void *d) | |
138 | { | |
139 | struct stack_trace_data *data = d; | |
140 | struct stack_trace *trace = data->trace; | |
141 | unsigned long addr = frame->pc; | |
142 | ||
143 | if (data->no_sched_functions && in_sched_functions(addr)) | |
144 | return 0; | |
145 | if (data->skip) { | |
146 | data->skip--; | |
147 | return 0; | |
148 | } | |
149 | ||
150 | trace->entries[trace->nr_entries++] = addr; | |
151 | ||
152 | return trace->nr_entries >= trace->max_entries; | |
153 | } | |
154 | ||
155 | void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace) | |
156 | { | |
157 | struct stack_trace_data data; | |
158 | struct stackframe frame; | |
159 | ||
160 | data.trace = trace; | |
161 | data.skip = trace->skip; | |
162 | ||
163 | if (tsk != current) { | |
164 | data.no_sched_functions = 1; | |
165 | frame.fp = thread_saved_fp(tsk); | |
166 | frame.sp = thread_saved_sp(tsk); | |
167 | frame.pc = thread_saved_pc(tsk); | |
168 | } else { | |
60ffc30d CM |
169 | data.no_sched_functions = 0; |
170 | frame.fp = (unsigned long)__builtin_frame_address(0); | |
bb28cec4 | 171 | frame.sp = current_stack_pointer; |
60ffc30d CM |
172 | frame.pc = (unsigned long)save_stack_trace_tsk; |
173 | } | |
20380bb3 AT |
174 | #ifdef CONFIG_FUNCTION_GRAPH_TRACER |
175 | frame.graph = tsk->curr_ret_stack; | |
176 | #endif | |
60ffc30d | 177 | |
fe13f95b | 178 | walk_stackframe(tsk, &frame, save_trace, &data); |
60ffc30d CM |
179 | if (trace->nr_entries < trace->max_entries) |
180 | trace->entries[trace->nr_entries++] = ULONG_MAX; | |
181 | } | |
182 | ||
183 | void save_stack_trace(struct stack_trace *trace) | |
184 | { | |
185 | save_stack_trace_tsk(current, trace); | |
186 | } | |
187 | EXPORT_SYMBOL_GPL(save_stack_trace); | |
188 | #endif |