1 /*
2  * Stack trace utility for OpenRISC
3  *
4  * Copyright (C) 2017 Stafford Horne <shorne@gmail.com>
5  *
6  * This file is licensed under the terms of the GNU General Public License
7  * version 2.  This program is licensed "as is" without any warranty of any
8  * kind, whether express or implied.
9  *
10  * Losely based on work from sh and powerpc.
11  */
12 
13 #include <linux/export.h>
14 #include <linux/sched.h>
15 #include <linux/sched/debug.h>
16 #include <linux/sched/task_stack.h>
17 #include <linux/stacktrace.h>
18 
19 #include <asm/processor.h>
20 #include <asm/unwinder.h>
21 
22 /*
23  * Save stack-backtrace addresses into a stack_trace buffer.
24  */
25 static void
26 save_stack_address(void *data, unsigned long addr, int reliable)
27 {
28 	struct stack_trace *trace = data;
29 
30 	if (!reliable)
31 		return;
32 
33 	if (trace->skip > 0) {
34 		trace->skip--;
35 		return;
36 	}
37 
38 	if (trace->nr_entries < trace->max_entries)
39 		trace->entries[trace->nr_entries++] = addr;
40 }
41 
42 void save_stack_trace(struct stack_trace *trace)
43 {
44 	unwind_stack(trace, (unsigned long *) &trace, save_stack_address);
45 }
46 EXPORT_SYMBOL_GPL(save_stack_trace);
47 
48 static void
49 save_stack_address_nosched(void *data, unsigned long addr, int reliable)
50 {
51 	struct stack_trace *trace = (struct stack_trace *)data;
52 
53 	if (!reliable)
54 		return;
55 
56 	if (in_sched_functions(addr))
57 		return;
58 
59 	if (trace->skip > 0) {
60 		trace->skip--;
61 		return;
62 	}
63 
64 	if (trace->nr_entries < trace->max_entries)
65 		trace->entries[trace->nr_entries++] = addr;
66 }
67 
68 void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
69 {
70 	unsigned long *sp = NULL;
71 
72 	if (!try_get_task_stack(tsk))
73 		return;
74 
75 	if (tsk == current)
76 		sp = (unsigned long *) &sp;
77 	else {
78 		unsigned long ksp;
79 
80 		/* Locate stack from kernel context */
81 		ksp = task_thread_info(tsk)->ksp;
82 		ksp += STACK_FRAME_OVERHEAD;	/* redzone */
83 		ksp += sizeof(struct pt_regs);
84 
85 		sp = (unsigned long *) ksp;
86 	}
87 
88 	unwind_stack(trace, sp, save_stack_address_nosched);
89 
90 	put_task_stack(tsk);
91 }
92 EXPORT_SYMBOL_GPL(save_stack_trace_tsk);
93 
94 void
95 save_stack_trace_regs(struct pt_regs *regs, struct stack_trace *trace)
96 {
97 	unwind_stack(trace, (unsigned long *) regs->sp,
98 		     save_stack_address_nosched);
99 }
100 EXPORT_SYMBOL_GPL(save_stack_trace_regs);
101