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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (C) 2008 ARM Limited
4 * Copyright (C) 2014 Regents of the University of California
5 */
6
7#include <linux/export.h>
8#include <linux/kallsyms.h>
9#include <linux/sched.h>
10#include <linux/sched/debug.h>
11#include <linux/sched/task_stack.h>
12#include <linux/stacktrace.h>
13#include <linux/ftrace.h>
14
15#include <asm/stacktrace.h>
16
17#ifdef CONFIG_FRAME_POINTER
18
19extern asmlinkage void ret_from_exception(void);
20
21void notrace walk_stackframe(struct task_struct *task, struct pt_regs *regs,
22 bool (*fn)(void *, unsigned long), void *arg)
23{
24 unsigned long fp, sp, pc;
25 int level = 0;
26
27 if (regs) {
28 fp = frame_pointer(regs);
29 sp = user_stack_pointer(regs);
30 pc = instruction_pointer(regs);
31 } else if (task == NULL || task == current) {
32 fp = (unsigned long)__builtin_frame_address(0);
33 sp = current_stack_pointer;
34 pc = (unsigned long)walk_stackframe;
35 level = -1;
36 } else {
37 /* task blocked in __switch_to */
38 fp = task->thread.s[0];
39 sp = task->thread.sp;
40 pc = task->thread.ra;
41 }
42
43 for (;;) {
44 unsigned long low, high;
45 struct stackframe *frame;
46
47 if (unlikely(!__kernel_text_address(pc) || (level++ >= 0 && !fn(arg, pc))))
48 break;
49
50 /* Validate frame pointer */
51 low = sp + sizeof(struct stackframe);
52 high = ALIGN(sp, THREAD_SIZE);
53 if (unlikely(fp < low || fp > high || fp & 0x7))
54 break;
55 /* Unwind stack frame */
56 frame = (struct stackframe *)fp - 1;
57 sp = fp;
58 if (regs && (regs->epc == pc) && (frame->fp & 0x7)) {
59 fp = frame->ra;
60 pc = regs->ra;
61 } else {
62 fp = frame->fp;
63 pc = ftrace_graph_ret_addr(current, NULL, frame->ra,
64 &frame->ra);
65 if (pc == (unsigned long)ret_from_exception) {
66 if (unlikely(!__kernel_text_address(pc) || !fn(arg, pc)))
67 break;
68
69 pc = ((struct pt_regs *)sp)->epc;
70 fp = ((struct pt_regs *)sp)->s0;
71 }
72 }
73
74 }
75}
76
77#else /* !CONFIG_FRAME_POINTER */
78
79void notrace walk_stackframe(struct task_struct *task,
80 struct pt_regs *regs, bool (*fn)(void *, unsigned long), void *arg)
81{
82 unsigned long sp, pc;
83 unsigned long *ksp;
84
85 if (regs) {
86 sp = user_stack_pointer(regs);
87 pc = instruction_pointer(regs);
88 } else if (task == NULL || task == current) {
89 sp = current_stack_pointer;
90 pc = (unsigned long)walk_stackframe;
91 } else {
92 /* task blocked in __switch_to */
93 sp = task->thread.sp;
94 pc = task->thread.ra;
95 }
96
97 if (unlikely(sp & 0x7))
98 return;
99
100 ksp = (unsigned long *)sp;
101 while (!kstack_end(ksp)) {
102 if (__kernel_text_address(pc) && unlikely(!fn(arg, pc)))
103 break;
104 pc = READ_ONCE_NOCHECK(*ksp++) - 0x4;
105 }
106}
107
108#endif /* CONFIG_FRAME_POINTER */
109
110static bool print_trace_address(void *arg, unsigned long pc)
111{
112 const char *loglvl = arg;
113
114 print_ip_sym(loglvl, pc);
115 return true;
116}
117
118noinline void dump_backtrace(struct pt_regs *regs, struct task_struct *task,
119 const char *loglvl)
120{
121 walk_stackframe(task, regs, print_trace_address, (void *)loglvl);
122}
123
124void show_stack(struct task_struct *task, unsigned long *sp, const char *loglvl)
125{
126 pr_cont("%sCall Trace:\n", loglvl);
127 dump_backtrace(NULL, task, loglvl);
128}
129
130static bool save_wchan(void *arg, unsigned long pc)
131{
132 if (!in_sched_functions(pc)) {
133 unsigned long *p = arg;
134 *p = pc;
135 return false;
136 }
137 return true;
138}
139
140unsigned long __get_wchan(struct task_struct *task)
141{
142 unsigned long pc = 0;
143
144 if (!try_get_task_stack(task))
145 return 0;
146 walk_stackframe(task, NULL, save_wchan, &pc);
147 put_task_stack(task);
148 return pc;
149}
150
151noinline void arch_stack_walk(stack_trace_consume_fn consume_entry, void *cookie,
152 struct task_struct *task, struct pt_regs *regs)
153{
154 walk_stackframe(task, regs, consume_entry, cookie);
155}
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (C) 2008 ARM Limited
4 * Copyright (C) 2014 Regents of the University of California
5 */
6
7#include <linux/export.h>
8#include <linux/kallsyms.h>
9#include <linux/sched.h>
10#include <linux/sched/debug.h>
11#include <linux/sched/task_stack.h>
12#include <linux/stacktrace.h>
13#include <linux/ftrace.h>
14
15#ifdef CONFIG_FRAME_POINTER
16
17struct stackframe {
18 unsigned long fp;
19 unsigned long ra;
20};
21
22void notrace walk_stackframe(struct task_struct *task, struct pt_regs *regs,
23 bool (*fn)(unsigned long, void *), void *arg)
24{
25 unsigned long fp, sp, pc;
26
27 if (regs) {
28 fp = frame_pointer(regs);
29 sp = user_stack_pointer(regs);
30 pc = instruction_pointer(regs);
31 } else if (task == NULL || task == current) {
32 const register unsigned long current_sp __asm__ ("sp");
33 fp = (unsigned long)__builtin_frame_address(0);
34 sp = current_sp;
35 pc = (unsigned long)walk_stackframe;
36 } else {
37 /* task blocked in __switch_to */
38 fp = task->thread.s[0];
39 sp = task->thread.sp;
40 pc = task->thread.ra;
41 }
42
43 for (;;) {
44 unsigned long low, high;
45 struct stackframe *frame;
46
47 if (unlikely(!__kernel_text_address(pc) || fn(pc, arg)))
48 break;
49
50 /* Validate frame pointer */
51 low = sp + sizeof(struct stackframe);
52 high = ALIGN(sp, THREAD_SIZE);
53 if (unlikely(fp < low || fp > high || fp & 0x7))
54 break;
55 /* Unwind stack frame */
56 frame = (struct stackframe *)fp - 1;
57 sp = fp;
58 fp = frame->fp;
59 pc = ftrace_graph_ret_addr(current, NULL, frame->ra,
60 (unsigned long *)(fp - 8));
61 }
62}
63
64#else /* !CONFIG_FRAME_POINTER */
65
66static void notrace walk_stackframe(struct task_struct *task,
67 struct pt_regs *regs, bool (*fn)(unsigned long, void *), void *arg)
68{
69 unsigned long sp, pc;
70 unsigned long *ksp;
71
72 if (regs) {
73 sp = user_stack_pointer(regs);
74 pc = instruction_pointer(regs);
75 } else if (task == NULL || task == current) {
76 const register unsigned long current_sp __asm__ ("sp");
77 sp = current_sp;
78 pc = (unsigned long)walk_stackframe;
79 } else {
80 /* task blocked in __switch_to */
81 sp = task->thread.sp;
82 pc = task->thread.ra;
83 }
84
85 if (unlikely(sp & 0x7))
86 return;
87
88 ksp = (unsigned long *)sp;
89 while (!kstack_end(ksp)) {
90 if (__kernel_text_address(pc) && unlikely(fn(pc, arg)))
91 break;
92 pc = (*ksp++) - 0x4;
93 }
94}
95
96#endif /* CONFIG_FRAME_POINTER */
97
98
99static bool print_trace_address(unsigned long pc, void *arg)
100{
101 print_ip_sym(pc);
102 return false;
103}
104
105void show_stack(struct task_struct *task, unsigned long *sp)
106{
107 pr_cont("Call Trace:\n");
108 walk_stackframe(task, NULL, print_trace_address, NULL);
109}
110
111
112static bool save_wchan(unsigned long pc, void *arg)
113{
114 if (!in_sched_functions(pc)) {
115 unsigned long *p = arg;
116 *p = pc;
117 return true;
118 }
119 return false;
120}
121
122unsigned long get_wchan(struct task_struct *task)
123{
124 unsigned long pc = 0;
125
126 if (likely(task && task != current && task->state != TASK_RUNNING))
127 walk_stackframe(task, NULL, save_wchan, &pc);
128 return pc;
129}
130
131
132#ifdef CONFIG_STACKTRACE
133
134static bool __save_trace(unsigned long pc, void *arg, bool nosched)
135{
136 struct stack_trace *trace = arg;
137
138 if (unlikely(nosched && in_sched_functions(pc)))
139 return false;
140 if (unlikely(trace->skip > 0)) {
141 trace->skip--;
142 return false;
143 }
144
145 trace->entries[trace->nr_entries++] = pc;
146 return (trace->nr_entries >= trace->max_entries);
147}
148
149static bool save_trace(unsigned long pc, void *arg)
150{
151 return __save_trace(pc, arg, false);
152}
153
154/*
155 * Save stack-backtrace addresses into a stack_trace buffer.
156 */
157void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
158{
159 walk_stackframe(tsk, NULL, save_trace, trace);
160}
161EXPORT_SYMBOL_GPL(save_stack_trace_tsk);
162
163void save_stack_trace(struct stack_trace *trace)
164{
165 save_stack_trace_tsk(NULL, trace);
166}
167EXPORT_SYMBOL_GPL(save_stack_trace);
168
169#endif /* CONFIG_STACKTRACE */