arch/sh/mm/alignment.c

   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 <asm/alignment.h>
  17 #include <asm/processor.h>
  18
  19 static unsigned long se_user;
  20 static unsigned long se_sys;
  21 static unsigned long se_half;
  22 static unsigned long se_word;
  23 static unsigned long se_dword;
  24 static unsigned long se_multi;
  25 /* bitfield: 1: warn 2: fixup 4: signal -> combinations 2|4 && 1|2|4 are not
  26    valid! */
  27 static int se_usermode = UM_WARN | UM_FIXUP;
  28 /* 0: no warning 1: print a warning message, disabled by default */
  29 static int se_kernmode_warn;
  30
  31 core_param(alignment, se_usermode, int, 0600);
  32
  33 void inc_unaligned_byte_access(void)
  34 {
  35         se_half++;
  36 }
  37
  38 void inc_unaligned_word_access(void)
  39 {
  40         se_word++;
  41 }
  42
  43 void inc_unaligned_dword_access(void)
  44 {
  45         se_dword++;
  46 }
  47
  48 void inc_unaligned_multi_access(void)
  49 {
  50         se_multi++;
  51 }
  52
  53 void inc_unaligned_user_access(void)
  54 {
  55         se_user++;
  56 }
  57
  58 void inc_unaligned_kernel_access(void)
  59 {
  60         se_sys++;
  61 }
  62
  63 /*
  64  * This defaults to the global policy which can be set from the command
  65  * line, while processes can overload their preferences via prctl().
  66  */
  67 unsigned int unaligned_user_action(void)
  68 {
  69         unsigned int action = se_usermode;
  70
  71         if (current->thread.flags & SH_THREAD_UAC_SIGBUS) {
  72                 action &= ~UM_FIXUP;
  73                 action |= UM_SIGNAL;
  74         }
  75
  76         if (current->thread.flags & SH_THREAD_UAC_NOPRINT)
  77                 action &= ~UM_WARN;
  78
  79         return action;
  80 }
  81
  82 int get_unalign_ctl(struct task_struct *tsk, unsigned long addr)
  83 {
  84         return put_user(tsk->thread.flags & SH_THREAD_UAC_MASK,
  85                         (unsigned int __user *)addr);
  86 }
  87
  88 int set_unalign_ctl(struct task_struct *tsk, unsigned int val)
  89 {
  90         tsk->thread.flags = (tsk->thread.flags & ~SH_THREAD_UAC_MASK) |
  91                             (val & SH_THREAD_UAC_MASK);
  92         return 0;
  93 }
  94
  95 void unaligned_fixups_notify(struct task_struct *tsk, insn_size_t insn,
  96                              struct pt_regs *regs)
  97 {
  98         if (user_mode(regs) && (se_usermode & UM_WARN) && printk_ratelimit())
  99                 pr_notice("Fixing up unaligned userspace access "
 100                           "in \"%s\" pid=%d pc=0x%p ins=0x%04hx\n",
 101                           tsk->comm, task_pid_nr(tsk),
 102                           (void *)instruction_pointer(regs), insn);
 103         else if (se_kernmode_warn && printk_ratelimit())
 104                 pr_notice("Fixing up unaligned kernel access "
 105                           "in \"%s\" pid=%d pc=0x%p ins=0x%04hx\n",
 106                           tsk->comm, task_pid_nr(tsk),
 107                           (void *)instruction_pointer(regs), insn);
 108 }
 109
 110 static const char *se_usermode_action[] = {
 111         "ignored",
 112         "warn",
 113         "fixup",
 114         "fixup+warn",
 115         "signal",
 116         "signal+warn"
 117 };
 118
 119 static int alignment_proc_show(struct seq_file *m, void *v)
 120 {
 121         seq_printf(m, "User:\t\t%lu\n", se_user);
 122         seq_printf(m, "System:\t\t%lu\n", se_sys);
 123         seq_printf(m, "Half:\t\t%lu\n", se_half);
 124         seq_printf(m, "Word:\t\t%lu\n", se_word);
 125         seq_printf(m, "DWord:\t\t%lu\n", se_dword);
 126         seq_printf(m, "Multi:\t\t%lu\n", se_multi);
 127         seq_printf(m, "User faults:\t%i (%s)\n", se_usermode,
 128                         se_usermode_action[se_usermode]);
 129         seq_printf(m, "Kernel faults:\t%i (fixup%s)\n", se_kernmode_warn,
 130                         se_kernmode_warn ? "+warn" : "");
 131         return 0;
 132 }
 133
 134 static int alignment_proc_open(struct inode *inode, struct file *file)
 135 {
 136         return single_open(file, alignment_proc_show, NULL);
 137 }
 138
 139 static ssize_t alignment_proc_write(struct file *file,
 140                 const char __user *buffer, size_t count, loff_t *pos)
 141 {
 142         int *data = PDE(file->f_path.dentry->d_inode)->data;
 143         char mode;
 144
 145         if (count > 0) {
 146                 if (get_user(mode, buffer))
 147                         return -EFAULT;
 148                 if (mode >= '0' && mode <= '5')
 149                         *data = mode - '0';
 150         }
 151         return count;
 152 }
 153
 154 static const struct file_operations alignment_proc_fops = {
 155         .owner          = THIS_MODULE,
 156         .open           = alignment_proc_open,
 157         .read           = seq_read,
 158         .llseek         = seq_lseek,
 159         .release        = single_release,
 160         .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  */
 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_fops, &se_usermode);
 179         if (!res)
 180                 return -ENOMEM;
 181
 182         res = proc_create_data("kernel_alignment", S_IWUSR | S_IRUGO, dir,
 183                                &alignment_proc_fops, &se_kernmode_warn);
 184         if (!res)
 185                 return -ENOMEM;
 186
 187         return 0;
 188 }
 189 fs_initcall(alignment_init);