xref: /openbmc/linux/arch/riscv/kernel/stacktrace.c (revision 5c88af59)
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 register unsigned long sp_in_global __asm__("sp");
18 
19 #ifdef CONFIG_FRAME_POINTER
20 
21 void 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 
26 	if (regs) {
27 		fp = frame_pointer(regs);
28 		sp = user_stack_pointer(regs);
29 		pc = instruction_pointer(regs);
30 	} else if (task == NULL || task == current) {
31 		fp = (unsigned long)__builtin_frame_address(0);
32 		sp = sp_in_global;
33 		pc = (unsigned long)walk_stackframe;
34 	} else {
35 		/* task blocked in __switch_to */
36 		fp = task->thread.s[0];
37 		sp = task->thread.sp;
38 		pc = task->thread.ra;
39 	}
40 
41 	for (;;) {
42 		unsigned long low, high;
43 		struct stackframe *frame;
44 
45 		if (unlikely(!__kernel_text_address(pc) || !fn(arg, pc)))
46 			break;
47 
48 		/* Validate frame pointer */
49 		low = sp + sizeof(struct stackframe);
50 		high = ALIGN(sp, THREAD_SIZE);
51 		if (unlikely(fp < low || fp > high || fp & 0x7))
52 			break;
53 		/* Unwind stack frame */
54 		frame = (struct stackframe *)fp - 1;
55 		sp = fp;
56 		if (regs && (regs->epc == pc) && (frame->fp & 0x7)) {
57 			fp = frame->ra;
58 			pc = regs->ra;
59 		} else {
60 			fp = frame->fp;
61 			pc = ftrace_graph_ret_addr(current, NULL, frame->ra,
62 						   (unsigned long *)(fp - 8));
63 		}
64 
65 	}
66 }
67 
68 #else /* !CONFIG_FRAME_POINTER */
69 
70 void notrace walk_stackframe(struct task_struct *task,
71 	struct pt_regs *regs, bool (*fn)(void *, unsigned long), void *arg)
72 {
73 	unsigned long sp, pc;
74 	unsigned long *ksp;
75 
76 	if (regs) {
77 		sp = user_stack_pointer(regs);
78 		pc = instruction_pointer(regs);
79 	} else if (task == NULL || task == current) {
80 		sp = sp_in_global;
81 		pc = (unsigned long)walk_stackframe;
82 	} else {
83 		/* task blocked in __switch_to */
84 		sp = task->thread.sp;
85 		pc = task->thread.ra;
86 	}
87 
88 	if (unlikely(sp & 0x7))
89 		return;
90 
91 	ksp = (unsigned long *)sp;
92 	while (!kstack_end(ksp)) {
93 		if (__kernel_text_address(pc) && unlikely(!fn(arg, pc)))
94 			break;
95 		pc = (*ksp++) - 0x4;
96 	}
97 }
98 
99 #endif /* CONFIG_FRAME_POINTER */
100 
101 static bool print_trace_address(void *arg, unsigned long pc)
102 {
103 	const char *loglvl = arg;
104 
105 	print_ip_sym(loglvl, pc);
106 	return true;
107 }
108 
109 void dump_backtrace(struct pt_regs *regs, struct task_struct *task,
110 		    const char *loglvl)
111 {
112 	pr_cont("%sCall Trace:\n", loglvl);
113 	walk_stackframe(task, regs, print_trace_address, (void *)loglvl);
114 }
115 
116 void show_stack(struct task_struct *task, unsigned long *sp, const char *loglvl)
117 {
118 	dump_backtrace(NULL, task, loglvl);
119 }
120 
121 static bool save_wchan(void *arg, unsigned long pc)
122 {
123 	if (!in_sched_functions(pc)) {
124 		unsigned long *p = arg;
125 		*p = pc;
126 		return false;
127 	}
128 	return true;
129 }
130 
131 unsigned long get_wchan(struct task_struct *task)
132 {
133 	unsigned long pc = 0;
134 
135 	if (likely(task && task != current && task->state != TASK_RUNNING))
136 		walk_stackframe(task, NULL, save_wchan, &pc);
137 	return pc;
138 }
139 
140 #ifdef CONFIG_STACKTRACE
141 
142 void arch_stack_walk(stack_trace_consume_fn consume_entry, void *cookie,
143 		     struct task_struct *task, struct pt_regs *regs)
144 {
145 	walk_stackframe(task, regs, consume_entry, cookie);
146 }
147 
148 #endif /* CONFIG_STACKTRACE */
149