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); 191