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Linux/arch/sh/mm/alignment.c

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  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 
 34 void inc_unaligned_byte_access(void)
 35 {
 36         se_half++;
 37 }
 38 
 39 void inc_unaligned_word_access(void)
 40 {
 41         se_word++;
 42 }
 43 
 44 void inc_unaligned_dword_access(void)
 45 {
 46         se_dword++;
 47 }
 48 
 49 void inc_unaligned_multi_access(void)
 50 {
 51         se_multi++;
 52 }
 53 
 54 void inc_unaligned_user_access(void)
 55 {
 56         se_user++;
 57 }
 58 
 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  */
 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 
 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 
 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 
 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 
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 
135 static int alignment_proc_open(struct inode *inode, struct file *file)
136 {
137         return single_open(file, alignment_proc_show, NULL);
138 }
139 
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 >= '' && mode <= '5')
150                         *data = mode - '';
151         }
152         return count;
153 }
154 
155 static const struct file_operations alignment_proc_fops = {
156         .owner          = THIS_MODULE,
157         .open           = alignment_proc_open,
158         .read           = seq_read,
159         .llseek         = seq_lseek,
160         .release        = single_release,
161         .write          = alignment_proc_write,
162 };
163 
164 /*
165  * This needs to be done after sysctl_init, otherwise sys/ will be
166  * overwritten.  Actually, this shouldn't be in sys/ at all since
167  * it isn't a sysctl, and it doesn't contain sysctl information.
168  * We now locate it in /proc/cpu/alignment instead.
169  */
170 static int __init alignment_init(void)
171 {
172         struct proc_dir_entry *dir, *res;
173 
174         dir = proc_mkdir("cpu", NULL);
175         if (!dir)
176                 return -ENOMEM;
177 
178         res = proc_create_data("alignment", S_IWUSR | S_IRUGO, dir,
179                                &alignment_proc_fops, &se_usermode);
180         if (!res)
181                 return -ENOMEM;
182 
183         res = proc_create_data("kernel_alignment", S_IWUSR | S_IRUGO, dir,
184                                &alignment_proc_fops, &se_kernmode_warn);
185         if (!res)
186                 return -ENOMEM;
187 
188         return 0;
189 }
190 fs_initcall(alignment_init);
191 

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