1/**
2 * Copyright (C) 2005 Brian Rogan <bcr6@cornell.edu>, IBM
3 *
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public License
6 * as published by the Free Software Foundation; either version
7 * 2 of the License, or (at your option) any later version.
8**/
9
10#include <linux/oprofile.h>
11#include <linux/sched.h>
12#include <asm/processor.h>
13#include <linux/uaccess.h>
14#include <asm/compat.h>
15#include <asm/oprofile_impl.h>
16
17#define STACK_SP(STACK)		*(STACK)
18
19#define STACK_LR64(STACK)	*((unsigned long *)(STACK) + 2)
20#define STACK_LR32(STACK)	*((unsigned int *)(STACK) + 1)
21
22#ifdef CONFIG_PPC64
23#define STACK_LR(STACK)		STACK_LR64(STACK)
24#else
25#define STACK_LR(STACK)		STACK_LR32(STACK)
26#endif
27
28static unsigned int user_getsp32(unsigned int sp, int is_first)
29{
30	unsigned int stack_frame[2];
31	void __user *p = compat_ptr(sp);
32
33	if (!access_ok(VERIFY_READ, p, sizeof(stack_frame)))
34		return 0;
35
36	/*
37	 * The most likely reason for this is that we returned -EFAULT,
38	 * which means that we've done all that we can do from
39	 * interrupt context.
40	 */
41	if (__copy_from_user_inatomic(stack_frame, p, sizeof(stack_frame)))
42		return 0;
43
44	if (!is_first)
45		oprofile_add_trace(STACK_LR32(stack_frame));
46
47	/*
48	 * We do not enforce increasing stack addresses here because
49	 * we may transition to a different stack, eg a signal handler.
50	 */
51	return STACK_SP(stack_frame);
52}
53
54#ifdef CONFIG_PPC64
55static unsigned long user_getsp64(unsigned long sp, int is_first)
56{
57	unsigned long stack_frame[3];
58
59	if (!access_ok(VERIFY_READ, (void __user *)sp, sizeof(stack_frame)))
60		return 0;
61
62	if (__copy_from_user_inatomic(stack_frame, (void __user *)sp,
63					sizeof(stack_frame)))
64		return 0;
65
66	if (!is_first)
67		oprofile_add_trace(STACK_LR64(stack_frame));
68
69	return STACK_SP(stack_frame);
70}
71#endif
72
73static unsigned long kernel_getsp(unsigned long sp, int is_first)
74{
75	unsigned long *stack_frame = (unsigned long *)sp;
76
77	if (!validate_sp(sp, current, STACK_FRAME_OVERHEAD))
78		return 0;
79
80	if (!is_first)
81		oprofile_add_trace(STACK_LR(stack_frame));
82
83	/*
84	 * We do not enforce increasing stack addresses here because
85	 * we might be transitioning from an interrupt stack to a kernel
86	 * stack. validate_sp() is designed to understand this, so just
87	 * use it.
88	 */
89	return STACK_SP(stack_frame);
90}
91
92void op_powerpc_backtrace(struct pt_regs * const regs, unsigned int depth)
93{
94	unsigned long sp = regs->gpr[1];
95	int first_frame = 1;
96
97	/* We ditch the top stackframe so need to loop through an extra time */
98	depth += 1;
99
100	if (!user_mode(regs)) {
101		while (depth--) {
102			sp = kernel_getsp(sp, first_frame);
103			if (!sp)
104				break;
105			first_frame = 0;
106		}
107	} else {
108		pagefault_disable();
109#ifdef CONFIG_PPC64
110		if (!is_32bit_task()) {
111			while (depth--) {
112				sp = user_getsp64(sp, first_frame);
113				if (!sp)
114					break;
115				first_frame = 0;
116			}
117			pagefault_enable();
118			return;
119		}
120#endif
121
122		while (depth--) {
123			sp = user_getsp32(sp, first_frame);
124			if (!sp)
125				break;
126			first_frame = 0;
127		}
128		pagefault_enable();
129	}
130}
131