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gerrit-public.fairphone.software / kernel / msm / b60c31d85a2a2f1a9c8623f1fb56e2688aa1e2b1 / . / arch / sh / oprofile / backtrace.c
blob: 9499a2914f89b4e10eeae491ddd1cd0a3975021f [file] [log] [blame]
Dave Peverley40a8b422008-12-16 09:35:40 +0900[diff] [blame]1/*
2 * SH specific backtracing code for oprofile
3 *
4 * Copyright 2007 STMicroelectronics Ltd.
5 *
6 * Author: Dave Peverley <dpeverley@mpc-data.co.uk>
7 *
8 * Based on ARM oprofile backtrace code by Richard Purdie and in turn, i386
9 * oprofile backtrace code by John Levon, David Smith
10 *
11 * This program is free software; you can redistribute it and/or modify
12 * it under the terms of the GNU General Public License version 2 as
13 * published by the Free Software Foundation.
14 *
15 */
16#include <linux/oprofile.h>
17#include <linux/sched.h>
18#include <linux/kallsyms.h>
19#include <linux/mm.h>
20#include <asm/ptrace.h>
21#include <asm/uaccess.h>
22#include <asm/sections.h>
23
24/* Limit to stop backtracing too far. */
25static int backtrace_limit = 20;
26
27static unsigned long *
28user_backtrace(unsigned long *stackaddr, struct pt_regs *regs)
29{
30 unsigned long buf_stack;
31
32 /* Also check accessibility of address */
33 if (!access_ok(VERIFY_READ, stackaddr, sizeof(unsigned long)))
34 return NULL;
35
36 if (__copy_from_user_inatomic(&buf_stack, stackaddr, sizeof(unsigned long)))
37 return NULL;
38
39 /* Quick paranoia check */
40 if (buf_stack & 3)
41 return NULL;
42
43 oprofile_add_trace(buf_stack);
44
45 stackaddr++;
46
47 return stackaddr;
48}
49
50/*
51 * | | /\ Higher addresses
52 * | |
53 * --------------- stack base (address of current_thread_info)
54 * | thread info |
55 * . .
56 * | stack |
57 * --------------- saved regs->regs[15] value if valid
58 * . .
59 * --------------- struct pt_regs stored on stack (struct pt_regs *)
60 * | |
61 * . .
62 * | |
63 * --------------- ???
64 * | |
65 * | | \/ Lower addresses
66 *
67 * Thus, &pt_regs <-> stack base restricts the valid(ish) fp values
68 */
69static int valid_kernel_stack(unsigned long *stackaddr, struct pt_regs *regs)
70{
71 unsigned long stack = (unsigned long)regs;
72 unsigned long stack_base = (stack & ~(THREAD_SIZE - 1)) + THREAD_SIZE;
73
74 return ((unsigned long)stackaddr > stack) && ((unsigned long)stackaddr < stack_base);
75}
76
77static unsigned long *
78kernel_backtrace(unsigned long *stackaddr, struct pt_regs *regs)
79{
80 unsigned long addr;
81
82 /*
83 * If not a valid kernel address, keep going till we find one
84 * or the SP stops being a valid address.
85 */
86 do {
87 addr = *stackaddr++;
Paul Mundt59de5802008-12-22 19:32:27 +0900[diff] [blame]88 oprofile_add_trace(addr);
Dave Peverley40a8b422008-12-16 09:35:40 +0900[diff] [blame]89 } while (valid_kernel_stack(stackaddr, regs));
90
91 return stackaddr;
92}
93
94void sh_backtrace(struct pt_regs * const regs, unsigned int depth)
95{
96 unsigned long *stackaddr;
97
98 /*
99 * Paranoia - clip max depth as we could get lost in the weeds.
100 */
101 if (depth > backtrace_limit)
102 depth = backtrace_limit;
103
104 stackaddr = (unsigned long *)regs->regs[15];
105 if (!user_mode(regs)) {
106 while (depth-- && valid_kernel_stack(stackaddr, regs))
107 stackaddr = kernel_backtrace(stackaddr, regs);
108
109 return;
110 }
111
112 while (depth-- && (stackaddr != NULL))
113 stackaddr = user_backtrace(stackaddr, regs);
114}