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3d256151 NV |
1 | /* |
2 | * AVR32 specific backtracing code for oprofile | |
3 | * | |
4 | * Copyright 2008 Weinmann GmbH | |
5 | * | |
6 | * Author: Nikolaus Voss <n.voss@weinmann.de> | |
7 | * | |
8 | * Based on i386 oprofile backtrace code by John Levon and David Smith | |
9 | * | |
10 | * This program is free software; you can redistribute it and/or modify | |
11 | * it under the terms of the GNU General Public License version 2 as | |
12 | * published by the Free Software Foundation. | |
13 | * | |
14 | */ | |
15 | ||
16 | #include <linux/oprofile.h> | |
17 | #include <linux/sched.h> | |
18 | #include <linux/uaccess.h> | |
19 | ||
20 | /* The first two words of each frame on the stack look like this if we have | |
21 | * frame pointers */ | |
22 | struct frame_head { | |
23 | unsigned long lr; | |
24 | struct frame_head *fp; | |
25 | }; | |
26 | ||
27 | /* copied from arch/avr32/kernel/process.c */ | |
28 | static inline int valid_stack_ptr(struct thread_info *tinfo, unsigned long p) | |
29 | { | |
30 | return (p > (unsigned long)tinfo) | |
31 | && (p < (unsigned long)tinfo + THREAD_SIZE - 3); | |
32 | } | |
33 | ||
34 | /* copied from arch/x86/oprofile/backtrace.c */ | |
35 | static struct frame_head *dump_user_backtrace(struct frame_head *head) | |
36 | { | |
37 | struct frame_head bufhead[2]; | |
38 | ||
39 | /* Also check accessibility of one struct frame_head beyond */ | |
40 | if (!access_ok(VERIFY_READ, head, sizeof(bufhead))) | |
41 | return NULL; | |
42 | if (__copy_from_user_inatomic(bufhead, head, sizeof(bufhead))) | |
43 | return NULL; | |
44 | ||
45 | oprofile_add_trace(bufhead[0].lr); | |
46 | ||
47 | /* frame pointers should strictly progress back up the stack | |
48 | * (towards higher addresses) */ | |
49 | if (bufhead[0].fp <= head) | |
50 | return NULL; | |
51 | ||
52 | return bufhead[0].fp; | |
53 | } | |
54 | ||
55 | void avr32_backtrace(struct pt_regs * const regs, unsigned int depth) | |
56 | { | |
57 | /* Get first frame pointer */ | |
58 | struct frame_head *head = (struct frame_head *)(regs->r7); | |
59 | ||
60 | if (!user_mode(regs)) { | |
61 | #ifdef CONFIG_FRAME_POINTER | |
62 | /* | |
63 | * Traverse the kernel stack from frame to frame up to | |
64 | * "depth" steps. | |
65 | */ | |
66 | while (depth-- && valid_stack_ptr(task_thread_info(current), | |
67 | (unsigned long)head)) { | |
68 | oprofile_add_trace(head->lr); | |
69 | if (head->fp <= head) | |
70 | break; | |
71 | head = head->fp; | |
72 | } | |
73 | #endif | |
74 | } else { | |
75 | /* Assume we have frame pointers in user mode process */ | |
76 | while (depth-- && head) | |
77 | head = dump_user_backtrace(head); | |
78 | } | |
79 | } | |
80 | ||
81 |