xref: /openbmc/linux/arch/x86/kernel/stacktrace.c (revision 82003e04)
1 /*
2  * Stack trace management functions
3  *
4  *  Copyright (C) 2006-2009 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
5  */
6 #include <linux/sched.h>
7 #include <linux/stacktrace.h>
8 #include <linux/export.h>
9 #include <linux/uaccess.h>
10 #include <asm/stacktrace.h>
11 #include <asm/unwind.h>
12 
13 static int save_stack_address(struct stack_trace *trace, unsigned long addr,
14 			      bool nosched)
15 {
16 	if (nosched && in_sched_functions(addr))
17 		return 0;
18 
19 	if (trace->skip > 0) {
20 		trace->skip--;
21 		return 0;
22 	}
23 
24 	if (trace->nr_entries >= trace->max_entries)
25 		return -1;
26 
27 	trace->entries[trace->nr_entries++] = addr;
28 	return 0;
29 }
30 
31 static void __save_stack_trace(struct stack_trace *trace,
32 			       struct task_struct *task, struct pt_regs *regs,
33 			       bool nosched)
34 {
35 	struct unwind_state state;
36 	unsigned long addr;
37 
38 	if (regs)
39 		save_stack_address(trace, regs->ip, nosched);
40 
41 	for (unwind_start(&state, task, regs, NULL); !unwind_done(&state);
42 	     unwind_next_frame(&state)) {
43 		addr = unwind_get_return_address(&state);
44 		if (!addr || save_stack_address(trace, addr, nosched))
45 			break;
46 	}
47 
48 	if (trace->nr_entries < trace->max_entries)
49 		trace->entries[trace->nr_entries++] = ULONG_MAX;
50 }
51 
52 /*
53  * Save stack-backtrace addresses into a stack_trace buffer.
54  */
55 void save_stack_trace(struct stack_trace *trace)
56 {
57 	__save_stack_trace(trace, current, NULL, false);
58 }
59 EXPORT_SYMBOL_GPL(save_stack_trace);
60 
61 void save_stack_trace_regs(struct pt_regs *regs, struct stack_trace *trace)
62 {
63 	__save_stack_trace(trace, current, regs, false);
64 }
65 
66 void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
67 {
68 	if (!try_get_task_stack(tsk))
69 		return;
70 
71 	__save_stack_trace(trace, tsk, NULL, true);
72 
73 	put_task_stack(tsk);
74 }
75 EXPORT_SYMBOL_GPL(save_stack_trace_tsk);
76 
77 /* Userspace stacktrace - based on kernel/trace/trace_sysprof.c */
78 
79 struct stack_frame_user {
80 	const void __user	*next_fp;
81 	unsigned long		ret_addr;
82 };
83 
84 static int
85 copy_stack_frame(const void __user *fp, struct stack_frame_user *frame)
86 {
87 	int ret;
88 
89 	if (!access_ok(VERIFY_READ, fp, sizeof(*frame)))
90 		return 0;
91 
92 	ret = 1;
93 	pagefault_disable();
94 	if (__copy_from_user_inatomic(frame, fp, sizeof(*frame)))
95 		ret = 0;
96 	pagefault_enable();
97 
98 	return ret;
99 }
100 
101 static inline void __save_stack_trace_user(struct stack_trace *trace)
102 {
103 	const struct pt_regs *regs = task_pt_regs(current);
104 	const void __user *fp = (const void __user *)regs->bp;
105 
106 	if (trace->nr_entries < trace->max_entries)
107 		trace->entries[trace->nr_entries++] = regs->ip;
108 
109 	while (trace->nr_entries < trace->max_entries) {
110 		struct stack_frame_user frame;
111 
112 		frame.next_fp = NULL;
113 		frame.ret_addr = 0;
114 		if (!copy_stack_frame(fp, &frame))
115 			break;
116 		if ((unsigned long)fp < regs->sp)
117 			break;
118 		if (frame.ret_addr) {
119 			trace->entries[trace->nr_entries++] =
120 				frame.ret_addr;
121 		}
122 		if (fp == frame.next_fp)
123 			break;
124 		fp = frame.next_fp;
125 	}
126 }
127 
128 void save_stack_trace_user(struct stack_trace *trace)
129 {
130 	/*
131 	 * Trace user stack if we are not a kernel thread
132 	 */
133 	if (current->mm) {
134 		__save_stack_trace_user(trace);
135 	}
136 	if (trace->nr_entries < trace->max_entries)
137 		trace->entries[trace->nr_entries++] = ULONG_MAX;
138 }
139 
140