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
20static int backtrace_stack(void *data, char *name)
21{
22	/* Yes, we want all stacks */
23	return 0;
24}
25
26static void backtrace_address(void *data, unsigned long addr, int reliable)
27{
28	unsigned int *depth = data;
29
30	if ((*depth)--)
31		oprofile_add_trace(addr);
32}
33
34static struct stacktrace_ops backtrace_ops = {
35	.stack		= backtrace_stack,
36	.address	= backtrace_address,
37	.walk_stack	= print_context_stack,
38};
39
40#ifdef CONFIG_COMPAT
41static struct stack_frame_ia32 *
42dump_user_backtrace_32(struct stack_frame_ia32 *head)
43{
44	/* Also check accessibility of one struct frame_head beyond: */
45	struct stack_frame_ia32 bufhead[2];
46	struct stack_frame_ia32 *fp;
47	unsigned long bytes;
48
49	bytes = copy_from_user_nmi(bufhead, head, sizeof(bufhead));
50	if (bytes != 0)
51		return NULL;
52
53	fp = (struct stack_frame_ia32 *) compat_ptr(bufhead[0].next_frame);
54
55	oprofile_add_trace(bufhead[0].return_address);
56
57	/* frame pointers should strictly progress back up the stack
58	* (towards higher addresses) */
59	if (head >= fp)
60		return NULL;
61
62	return fp;
63}
64
65static inline int
66x86_backtrace_32(struct pt_regs * const regs, unsigned int depth)
67{
68	struct stack_frame_ia32 *head;
69
70	/* User process is IA32 */
71	if (!current || !test_thread_flag(TIF_IA32))
72		return 0;
73
74	head = (struct stack_frame_ia32 *) regs->bp;
75	while (depth-- && head)
76		head = dump_user_backtrace_32(head);
77
78	return 1;
79}
80
81#else
82static inline int
83x86_backtrace_32(struct pt_regs * const regs, unsigned int depth)
84{
85	return 0;
86}
87#endif /* CONFIG_COMPAT */
88
89static struct stack_frame *dump_user_backtrace(struct stack_frame *head)
90{
91	/* Also check accessibility of one struct frame_head beyond: */
92	struct stack_frame bufhead[2];
93	unsigned long bytes;
94
95	bytes = copy_from_user_nmi(bufhead, head, sizeof(bufhead));
96	if (bytes != 0)
97		return NULL;
98
99	oprofile_add_trace(bufhead[0].return_address);
100
101	/* frame pointers should strictly progress back up the stack
102	 * (towards higher addresses) */
103	if (head >= bufhead[0].next_frame)
104		return NULL;
105
106	return bufhead[0].next_frame;
107}
108
109void
110x86_backtrace(struct pt_regs * const regs, unsigned int depth)
111{
112	struct stack_frame *head = (struct stack_frame *)frame_pointer(regs);
113
114	if (!user_mode(regs)) {
115		unsigned long stack = kernel_stack_pointer(regs);
116		if (depth)
117			dump_trace(NULL, regs, (unsigned long *)stack, 0,
118				   &backtrace_ops, &depth);
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