1 /*
2 * Alignment access counters and corresponding user-space interfaces.
3 *
4 * Copyright (C) 2009 ST Microelectronics
5 * Copyright (C) 2009 - 2010 Paul Mundt
6 *
7 * This file is subject to the terms and conditions of the GNU General Public
8 * License. See the file "COPYING" in the main directory of this archive
9 * for more details.
10 */
11 #include <linux/module.h>
12 #include <linux/kernel.h>
13 #include <linux/seq_file.h>
14 #include <linux/proc_fs.h>
15 #include <linux/uaccess.h>
16 #include <linux/ratelimit.h>
17 #include <asm/alignment.h>
18 #include <asm/processor.h>
19
20 static unsigned long se_user;
21 static unsigned long se_sys;
22 static unsigned long se_half;
23 static unsigned long se_word;
24 static unsigned long se_dword;
25 static unsigned long se_multi;
26 /* bitfield: 1: warn 2: fixup 4: signal -> combinations 2|4 && 1|2|4 are not
27 valid! */
28 static int se_usermode = UM_WARN | UM_FIXUP;
29 /* 0: no warning 1: print a warning message, disabled by default */
30 static int se_kernmode_warn;
31
32 core_param(alignment, se_usermode, int, 0600);
33
inc_unaligned_byte_access(void)34 void inc_unaligned_byte_access(void)
35 {
36 se_half++;
37 }
38
inc_unaligned_word_access(void)39 void inc_unaligned_word_access(void)
40 {
41 se_word++;
42 }
43
inc_unaligned_dword_access(void)44 void inc_unaligned_dword_access(void)
45 {
46 se_dword++;
47 }
48
inc_unaligned_multi_access(void)49 void inc_unaligned_multi_access(void)
50 {
51 se_multi++;
52 }
53
inc_unaligned_user_access(void)54 void inc_unaligned_user_access(void)
55 {
56 se_user++;
57 }
58
inc_unaligned_kernel_access(void)59 void inc_unaligned_kernel_access(void)
60 {
61 se_sys++;
62 }
63
64 /*
65 * This defaults to the global policy which can be set from the command
66 * line, while processes can overload their preferences via prctl().
67 */
unaligned_user_action(void)68 unsigned int unaligned_user_action(void)
69 {
70 unsigned int action = se_usermode;
71
72 if (current->thread.flags & SH_THREAD_UAC_SIGBUS) {
73 action &= ~UM_FIXUP;
74 action |= UM_SIGNAL;
75 }
76
77 if (current->thread.flags & SH_THREAD_UAC_NOPRINT)
78 action &= ~UM_WARN;
79
80 return action;
81 }
82
get_unalign_ctl(struct task_struct * tsk,unsigned long addr)83 int get_unalign_ctl(struct task_struct *tsk, unsigned long addr)
84 {
85 return put_user(tsk->thread.flags & SH_THREAD_UAC_MASK,
86 (unsigned int __user *)addr);
87 }
88
set_unalign_ctl(struct task_struct * tsk,unsigned int val)89 int set_unalign_ctl(struct task_struct *tsk, unsigned int val)
90 {
91 tsk->thread.flags = (tsk->thread.flags & ~SH_THREAD_UAC_MASK) |
92 (val & SH_THREAD_UAC_MASK);
93 return 0;
94 }
95
unaligned_fixups_notify(struct task_struct * tsk,insn_size_t insn,struct pt_regs * regs)96 void unaligned_fixups_notify(struct task_struct *tsk, insn_size_t insn,
97 struct pt_regs *regs)
98 {
99 if (user_mode(regs) && (se_usermode & UM_WARN))
100 pr_notice_ratelimited("Fixing up unaligned userspace access "
101 "in \"%s\" pid=%d pc=0x%p ins=0x%04hx\n",
102 tsk->comm, task_pid_nr(tsk),
103 (void *)instruction_pointer(regs), insn);
104 else if (se_kernmode_warn)
105 pr_notice_ratelimited("Fixing up unaligned kernel access "
106 "in \"%s\" pid=%d pc=0x%p ins=0x%04hx\n",
107 tsk->comm, task_pid_nr(tsk),
108 (void *)instruction_pointer(regs), insn);
109 }
110
111 static const char *se_usermode_action[] = {
112 "ignored",
113 "warn",
114 "fixup",
115 "fixup+warn",
116 "signal",
117 "signal+warn"
118 };
119
alignment_proc_show(struct seq_file * m,void * v)120 static int alignment_proc_show(struct seq_file *m, void *v)
121 {
122 seq_printf(m, "User:\t\t%lu\n", se_user);
123 seq_printf(m, "System:\t\t%lu\n", se_sys);
124 seq_printf(m, "Half:\t\t%lu\n", se_half);
125 seq_printf(m, "Word:\t\t%lu\n", se_word);
126 seq_printf(m, "DWord:\t\t%lu\n", se_dword);
127 seq_printf(m, "Multi:\t\t%lu\n", se_multi);
128 seq_printf(m, "User faults:\t%i (%s)\n", se_usermode,
129 se_usermode_action[se_usermode]);
130 seq_printf(m, "Kernel faults:\t%i (fixup%s)\n", se_kernmode_warn,
131 se_kernmode_warn ? "+warn" : "");
132 return 0;
133 }
134
alignment_proc_open(struct inode * inode,struct file * file)135 static int alignment_proc_open(struct inode *inode, struct file *file)
136 {
137 return single_open(file, alignment_proc_show, NULL);
138 }
139
alignment_proc_write(struct file * file,const char __user * buffer,size_t count,loff_t * pos)140 static ssize_t alignment_proc_write(struct file *file,
141 const char __user *buffer, size_t count, loff_t *pos)
142 {
143 int *data = PDE_DATA(file_inode(file));
144 char mode;
145
146 if (count > 0) {
147 if (get_user(mode, buffer))
148 return -EFAULT;
149 if (mode >= '0' && mode <= '5')
150 *data = mode - '0';
151 }
152 return count;
153 }
154
155 static const struct proc_ops alignment_proc_ops = {
156 .proc_open = alignment_proc_open,
157 .proc_read = seq_read,
158 .proc_lseek = seq_lseek,
159 .proc_release = single_release,
160 .proc_write = alignment_proc_write,
161 };
162
163 /*
164 * This needs to be done after sysctl_init, otherwise sys/ will be
165 * overwritten. Actually, this shouldn't be in sys/ at all since
166 * it isn't a sysctl, and it doesn't contain sysctl information.
167 * We now locate it in /proc/cpu/alignment instead.
168 */
alignment_init(void)169 static int __init alignment_init(void)
170 {
171 struct proc_dir_entry *dir, *res;
172
173 dir = proc_mkdir("cpu", NULL);
174 if (!dir)
175 return -ENOMEM;
176
177 res = proc_create_data("alignment", S_IWUSR | S_IRUGO, dir,
178 &alignment_proc_ops, &se_usermode);
179 if (!res)
180 return -ENOMEM;
181
182 res = proc_create_data("kernel_alignment", S_IWUSR | S_IRUGO, dir,
183 &alignment_proc_ops, &se_kernmode_warn);
184 if (!res)
185 return -ENOMEM;
186
187 return 0;
188 }
189 fs_initcall(alignment_init);
190
