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 <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 >= '0' && mode <= '5')
 150                         *data = mode - '0';
 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);