1/**
2 * @file backtrace.c
3 *
4 * @remark Copyright 2002 OProfile authors
5 * @remark Read the file COPYING
6 *
7 * @author John Levon
8 * @author David Smith
9 */
10
11#include <linux/oprofile.h>
12#include <linux/sched.h>
13#include <linux/mm.h>
14#include <linux/compat.h>
15#include <linux/uaccess.h>
16
17#include <asm/ptrace.h>
18#include <asm/stacktrace.h>
19#include <asm/unwind.h>
20
21#ifdef CONFIG_COMPAT
22static struct stack_frame_ia32 *
23dump_user_backtrace_32(struct stack_frame_ia32 *head)
24{
25	/* Also check accessibility of one struct frame_head beyond: */
26	struct stack_frame_ia32 bufhead[2];
27	struct stack_frame_ia32 *fp;
28	unsigned long bytes;
29
30	bytes = copy_from_user_nmi(bufhead, head, sizeof(bufhead));
31	if (bytes != 0)
32		return NULL;
33
34	fp = (struct stack_frame_ia32 *) compat_ptr(bufhead[0].next_frame);
35
36	oprofile_add_trace(bufhead[0].return_address);
37
38	/* frame pointers should strictly progress back up the stack
39	* (towards higher addresses) */
40	if (head >= fp)
41		return NULL;
42
43	return fp;
44}
45
46static inline int
47x86_backtrace_32(struct pt_regs * const regs, unsigned int depth)
48{
49	struct stack_frame_ia32 *head;
50
51	/* User process is IA32 */
52	if (!current || !test_thread_flag(TIF_IA32))
53		return 0;
54
55	head = (struct stack_frame_ia32 *) regs->bp;
56	while (depth-- && head)
57		head = dump_user_backtrace_32(head);
58
59	return 1;
60}
61
62#else
63static inline int
64x86_backtrace_32(struct pt_regs * const regs, unsigned int depth)
65{
66	return 0;
67}
68#endif /* CONFIG_COMPAT */
69
70static struct stack_frame *dump_user_backtrace(struct stack_frame *head)
71{
72	/* Also check accessibility of one struct frame_head beyond: */
73	struct stack_frame bufhead[2];
74	unsigned long bytes;
75
76	bytes = copy_from_user_nmi(bufhead, head, sizeof(bufhead));
77	if (bytes != 0)
78		return NULL;
79
80	oprofile_add_trace(bufhead[0].return_address);
81
82	/* frame pointers should strictly progress back up the stack
83	 * (towards higher addresses) */
84	if (head >= bufhead[0].next_frame)
85		return NULL;
86
87	return bufhead[0].next_frame;
88}
89
90void
91x86_backtrace(struct pt_regs * const regs, unsigned int depth)
92{
93	struct stack_frame *head = (struct stack_frame *)frame_pointer(regs);
94
95	if (!user_mode(regs)) {
96		struct unwind_state state;
97		unsigned long addr;
98
99		if (!depth)
100			return;
101
102		oprofile_add_trace(regs->ip);
103
104		if (!--depth)
105			return;
106
107		for (unwind_start(&state, current, regs, NULL);
108		     !unwind_done(&state); unwind_next_frame(&state)) {
109			addr = unwind_get_return_address(&state);
110			if (!addr)
111				break;
112
113			oprofile_add_trace(addr);
114
115			if (!--depth)
116				break;
117		}
118
119		return;
120	}
121
122	if (x86_backtrace_32(regs, depth))
123		return;
124
125	while (depth-- && head)
126		head = dump_user_backtrace(head);
127}
128