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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
15register unsigned long sp_in_global __asm__("sp");
16
17#ifdef CONFIG_FRAME_POINTER
18
19struct stackframe {
20 unsigned long fp;
21 unsigned long ra;
22};
23
24void notrace walk_stackframe(struct task_struct *task, struct pt_regs *regs,
25 bool (*fn)(unsigned long, void *), void *arg)
26{
27 unsigned long fp, sp, pc;
28
29 if (regs) {
30 fp = frame_pointer(regs);
31 sp = user_stack_pointer(regs);
32 pc = instruction_pointer(regs);
33 } else if (task == NULL || task == current) {
34 const register unsigned long current_sp = sp_in_global;
35 fp = (unsigned long)__builtin_frame_address(0);
36 sp = current_sp;
37 pc = (unsigned long)walk_stackframe;
38 } else {
39 /* task blocked in __switch_to */
40 fp = task->thread.s[0];
41 sp = task->thread.sp;
42 pc = task->thread.ra;
43 }
44
45 for (;;) {
46 unsigned long low, high;
47 struct stackframe *frame;
48
49 if (unlikely(!__kernel_text_address(pc) || fn(pc, arg)))
50 break;
51
52 /* Validate frame pointer */
53 low = sp + sizeof(struct stackframe);
54 high = ALIGN(sp, THREAD_SIZE);
55 if (unlikely(fp < low || fp > high || fp & 0x7))
56 break;
57 /* Unwind stack frame */
58 frame = (struct stackframe *)fp - 1;
59 sp = fp;
60 fp = frame->fp;
61 pc = ftrace_graph_ret_addr(current, NULL, frame->ra,
62 (unsigned long *)(fp - 8));
63 }
64}
65
66#else /* !CONFIG_FRAME_POINTER */
67
68void notrace walk_stackframe(struct task_struct *task,
69 struct pt_regs *regs, bool (*fn)(unsigned long, void *), void *arg)
70{
71 unsigned long sp, pc;
72 unsigned long *ksp;
73
74 if (regs) {
75 sp = user_stack_pointer(regs);
76 pc = instruction_pointer(regs);
77 } else if (task == NULL || task == current) {
78 sp = sp_in_global;
79 pc = (unsigned long)walk_stackframe;
80 } else {
81 /* task blocked in __switch_to */
82 sp = task->thread.sp;
83 pc = task->thread.ra;
84 }
85
86 if (unlikely(sp & 0x7))
87 return;
88
89 ksp = (unsigned long *)sp;
90 while (!kstack_end(ksp)) {
91 if (__kernel_text_address(pc) && unlikely(fn(pc, arg)))
92 break;
93 pc = (*ksp++) - 0x4;
94 }
95}
96
97#endif /* CONFIG_FRAME_POINTER */
98
99
100static bool print_trace_address(unsigned long pc, void *arg)
101{
102 const char *loglvl = arg;
103
104 print_ip_sym(loglvl, pc);
105 return false;
106}
107
108void show_stack(struct task_struct *task, unsigned long *sp, const char *loglvl)
109{
110 pr_cont("Call Trace:\n");
111 walk_stackframe(task, NULL, print_trace_address, (void *)loglvl);
112}
113
114static bool save_wchan(unsigned long pc, void *arg)
115{
116 if (!in_sched_functions(pc)) {
117 unsigned long *p = arg;
118 *p = pc;
119 return true;
120 }
121 return false;
122}
123
124unsigned long get_wchan(struct task_struct *task)
125{
126 unsigned long pc = 0;
127
128 if (likely(task && task != current && task->state != TASK_RUNNING))
129 walk_stackframe(task, NULL, save_wchan, &pc);
130 return pc;
131}
132
133
134#ifdef CONFIG_STACKTRACE
135
136static bool __save_trace(unsigned long pc, void *arg, bool nosched)
137{
138 struct stack_trace *trace = arg;
139
140 if (unlikely(nosched && in_sched_functions(pc)))
141 return false;
142 if (unlikely(trace->skip > 0)) {
143 trace->skip--;
144 return false;
145 }
146
147 trace->entries[trace->nr_entries++] = pc;
148 return (trace->nr_entries >= trace->max_entries);
149}
150
151static bool save_trace(unsigned long pc, void *arg)
152{
153 return __save_trace(pc, arg, false);
154}
155
156/*
157 * Save stack-backtrace addresses into a stack_trace buffer.
158 */
159void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
160{
161 walk_stackframe(tsk, NULL, save_trace, trace);
162}
163EXPORT_SYMBOL_GPL(save_stack_trace_tsk);
164
165void save_stack_trace(struct stack_trace *trace)
166{
167 save_stack_trace_tsk(NULL, trace);
168}
169EXPORT_SYMBOL_GPL(save_stack_trace);
170
171#endif /* CONFIG_STACKTRACE */
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
21static inline int fp_is_valid(unsigned long fp, unsigned long sp)
22{
23 unsigned long low, high;
24
25 low = sp + sizeof(struct stackframe);
26 high = ALIGN(sp, THREAD_SIZE);
27
28 return !(fp < low || fp > high || fp & 0x07);
29}
30
31void notrace walk_stackframe(struct task_struct *task, struct pt_regs *regs,
32 bool (*fn)(void *, unsigned long), void *arg)
33{
34 unsigned long fp, sp, pc;
35 int level = 0;
36
37 if (regs) {
38 fp = frame_pointer(regs);
39 sp = user_stack_pointer(regs);
40 pc = instruction_pointer(regs);
41 } else if (task == NULL || task == current) {
42 fp = (unsigned long)__builtin_frame_address(0);
43 sp = current_stack_pointer;
44 pc = (unsigned long)walk_stackframe;
45 level = -1;
46 } else {
47 /* task blocked in __switch_to */
48 fp = task->thread.s[0];
49 sp = task->thread.sp;
50 pc = task->thread.ra;
51 }
52
53 for (;;) {
54 struct stackframe *frame;
55
56 if (unlikely(!__kernel_text_address(pc) || (level++ >= 0 && !fn(arg, pc))))
57 break;
58
59 if (unlikely(!fp_is_valid(fp, sp)))
60 break;
61
62 /* Unwind stack frame */
63 frame = (struct stackframe *)fp - 1;
64 sp = fp;
65 if (regs && (regs->epc == pc) && fp_is_valid(frame->ra, sp)) {
66 /* We hit function where ra is not saved on the stack */
67 fp = frame->ra;
68 pc = regs->ra;
69 } else {
70 fp = frame->fp;
71 pc = ftrace_graph_ret_addr(current, NULL, frame->ra,
72 &frame->ra);
73 if (pc == (unsigned long)ret_from_exception) {
74 if (unlikely(!__kernel_text_address(pc) || !fn(arg, pc)))
75 break;
76
77 pc = ((struct pt_regs *)sp)->epc;
78 fp = ((struct pt_regs *)sp)->s0;
79 }
80 }
81
82 }
83}
84
85#else /* !CONFIG_FRAME_POINTER */
86
87void notrace walk_stackframe(struct task_struct *task,
88 struct pt_regs *regs, bool (*fn)(void *, unsigned long), void *arg)
89{
90 unsigned long sp, pc;
91 unsigned long *ksp;
92
93 if (regs) {
94 sp = user_stack_pointer(regs);
95 pc = instruction_pointer(regs);
96 } else if (task == NULL || task == current) {
97 sp = current_stack_pointer;
98 pc = (unsigned long)walk_stackframe;
99 } else {
100 /* task blocked in __switch_to */
101 sp = task->thread.sp;
102 pc = task->thread.ra;
103 }
104
105 if (unlikely(sp & 0x7))
106 return;
107
108 ksp = (unsigned long *)sp;
109 while (!kstack_end(ksp)) {
110 if (__kernel_text_address(pc) && unlikely(!fn(arg, pc)))
111 break;
112 pc = READ_ONCE_NOCHECK(*ksp++) - 0x4;
113 }
114}
115
116#endif /* CONFIG_FRAME_POINTER */
117
118static bool print_trace_address(void *arg, unsigned long pc)
119{
120 const char *loglvl = arg;
121
122 print_ip_sym(loglvl, pc);
123 return true;
124}
125
126noinline void dump_backtrace(struct pt_regs *regs, struct task_struct *task,
127 const char *loglvl)
128{
129 walk_stackframe(task, regs, print_trace_address, (void *)loglvl);
130}
131
132void show_stack(struct task_struct *task, unsigned long *sp, const char *loglvl)
133{
134 pr_cont("%sCall Trace:\n", loglvl);
135 dump_backtrace(NULL, task, loglvl);
136}
137
138static bool save_wchan(void *arg, unsigned long pc)
139{
140 if (!in_sched_functions(pc)) {
141 unsigned long *p = arg;
142 *p = pc;
143 return false;
144 }
145 return true;
146}
147
148unsigned long __get_wchan(struct task_struct *task)
149{
150 unsigned long pc = 0;
151
152 if (!try_get_task_stack(task))
153 return 0;
154 walk_stackframe(task, NULL, save_wchan, &pc);
155 put_task_stack(task);
156 return pc;
157}
158
159noinline void arch_stack_walk(stack_trace_consume_fn consume_entry, void *cookie,
160 struct task_struct *task, struct pt_regs *regs)
161{
162 walk_stackframe(task, regs, consume_entry, cookie);
163}