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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 handle_exception(void);
20extern unsigned long ret_from_exception_end;
21
22static inline int fp_is_valid(unsigned long fp, unsigned long sp)
23{
24 unsigned long low, high;
25
26 low = sp + sizeof(struct stackframe);
27 high = ALIGN(sp, THREAD_SIZE);
28
29 return !(fp < low || fp > high || fp & 0x07);
30}
31
32void notrace walk_stackframe(struct task_struct *task, struct pt_regs *regs,
33 bool (*fn)(void *, unsigned long), void *arg)
34{
35 unsigned long fp, sp, pc;
36 int graph_idx = 0;
37 int level = 0;
38
39 if (regs) {
40 fp = frame_pointer(regs);
41 sp = user_stack_pointer(regs);
42 pc = instruction_pointer(regs);
43 } else if (task == NULL || task == current) {
44 fp = (unsigned long)__builtin_frame_address(0);
45 sp = current_stack_pointer;
46 pc = (unsigned long)walk_stackframe;
47 level = -1;
48 } else {
49 /* task blocked in __switch_to */
50 fp = task->thread.s[0];
51 sp = task->thread.sp;
52 pc = task->thread.ra;
53 }
54
55 for (;;) {
56 struct stackframe *frame;
57
58 if (unlikely(!__kernel_text_address(pc) || (level++ >= 0 && !fn(arg, pc))))
59 break;
60
61 if (unlikely(!fp_is_valid(fp, sp)))
62 break;
63
64 /* Unwind stack frame */
65 frame = (struct stackframe *)fp - 1;
66 sp = fp;
67 if (regs && (regs->epc == pc) && fp_is_valid(frame->ra, sp)) {
68 /* We hit function where ra is not saved on the stack */
69 fp = frame->ra;
70 pc = regs->ra;
71 } else {
72 fp = frame->fp;
73 pc = ftrace_graph_ret_addr(current, &graph_idx, frame->ra,
74 &frame->ra);
75 if (pc >= (unsigned long)handle_exception &&
76 pc < (unsigned long)&ret_from_exception_end) {
77 if (unlikely(!__kernel_text_address(pc) || !fn(arg, pc)))
78 break;
79
80 pc = ((struct pt_regs *)sp)->epc;
81 fp = ((struct pt_regs *)sp)->s0;
82 }
83 }
84
85 }
86}
87
88#else /* !CONFIG_FRAME_POINTER */
89
90void notrace walk_stackframe(struct task_struct *task,
91 struct pt_regs *regs, bool (*fn)(void *, unsigned long), void *arg)
92{
93 unsigned long sp, pc;
94 unsigned long *ksp;
95
96 if (regs) {
97 sp = user_stack_pointer(regs);
98 pc = instruction_pointer(regs);
99 } else if (task == NULL || task == current) {
100 sp = current_stack_pointer;
101 pc = (unsigned long)walk_stackframe;
102 } else {
103 /* task blocked in __switch_to */
104 sp = task->thread.sp;
105 pc = task->thread.ra;
106 }
107
108 if (unlikely(sp & 0x7))
109 return;
110
111 ksp = (unsigned long *)sp;
112 while (!kstack_end(ksp)) {
113 if (__kernel_text_address(pc) && unlikely(!fn(arg, pc)))
114 break;
115 pc = READ_ONCE_NOCHECK(*ksp++) - 0x4;
116 }
117}
118
119#endif /* CONFIG_FRAME_POINTER */
120
121static bool print_trace_address(void *arg, unsigned long pc)
122{
123 const char *loglvl = arg;
124
125 print_ip_sym(loglvl, pc);
126 return true;
127}
128
129noinline void dump_backtrace(struct pt_regs *regs, struct task_struct *task,
130 const char *loglvl)
131{
132 walk_stackframe(task, regs, print_trace_address, (void *)loglvl);
133}
134
135void show_stack(struct task_struct *task, unsigned long *sp, const char *loglvl)
136{
137 pr_cont("%sCall Trace:\n", loglvl);
138 dump_backtrace(NULL, task, loglvl);
139}
140
141static bool save_wchan(void *arg, unsigned long pc)
142{
143 if (!in_sched_functions(pc)) {
144 unsigned long *p = arg;
145 *p = pc;
146 return false;
147 }
148 return true;
149}
150
151unsigned long __get_wchan(struct task_struct *task)
152{
153 unsigned long pc = 0;
154
155 if (!try_get_task_stack(task))
156 return 0;
157 walk_stackframe(task, NULL, save_wchan, &pc);
158 put_task_stack(task);
159 return pc;
160}
161
162noinline noinstr void arch_stack_walk(stack_trace_consume_fn consume_entry, void *cookie,
163 struct task_struct *task, struct pt_regs *regs)
164{
165 walk_stackframe(task, regs, consume_entry, cookie);
166}
167
168/*
169 * Get the return address for a single stackframe and return a pointer to the
170 * next frame tail.
171 */
172static unsigned long unwind_user_frame(stack_trace_consume_fn consume_entry,
173 void *cookie, unsigned long fp,
174 unsigned long reg_ra)
175{
176 struct stackframe buftail;
177 unsigned long ra = 0;
178 unsigned long __user *user_frame_tail =
179 (unsigned long __user *)(fp - sizeof(struct stackframe));
180
181 /* Check accessibility of one struct frame_tail beyond */
182 if (!access_ok(user_frame_tail, sizeof(buftail)))
183 return 0;
184 if (__copy_from_user_inatomic(&buftail, user_frame_tail,
185 sizeof(buftail)))
186 return 0;
187
188 ra = reg_ra ? : buftail.ra;
189
190 fp = buftail.fp;
191 if (!ra || !consume_entry(cookie, ra))
192 return 0;
193
194 return fp;
195}
196
197void arch_stack_walk_user(stack_trace_consume_fn consume_entry, void *cookie,
198 const struct pt_regs *regs)
199{
200 unsigned long fp = 0;
201
202 fp = regs->s0;
203 if (!consume_entry(cookie, regs->epc))
204 return;
205
206 fp = unwind_user_frame(consume_entry, cookie, fp, regs->ra);
207 while (fp && !(fp & 0x7))
208 fp = unwind_user_frame(consume_entry, cookie, fp, 0);
209}