arch/s390/lib/uaccess.c

   1 /*
   2  *  Standard user space access functions based on mvcp/mvcs and doing
   3  *  interesting things in the secondary space mode.
   4  *
   5  *    Copyright IBM Corp. 2006,2014
   6  *    Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com),
   7  *               Gerald Schaefer (gerald.schaefer@de.ibm.com)
   8  */
   9
  10 #include <linux/jump_label.h>
  11 #include <linux/uaccess.h>
  12 #include <linux/export.h>
  13 #include <linux/errno.h>
  14 #include <linux/mm.h>
  15 #include <asm/mmu_context.h>
  16 #include <asm/facility.h>
  17
  18 static struct static_key have_mvcos = STATIC_KEY_INIT_FALSE;
  19
  20 static inline unsigned long copy_from_user_mvcos(void *x, const void __user *ptr,
  21                                                  unsigned long size)
  22 {
  23         register unsigned long reg0 asm("0") = 0x81UL;
  24         unsigned long tmp1, tmp2;
  25
  26         tmp1 = -4096UL;
  27         asm volatile(
  28                 "0: .insn ss,0xc80000000000,0(%0,%2),0(%1),0\n"
  29                 "9: jz    7f\n"
  30                 "1: algr  %0,%3\n"
  31                 "   slgr  %1,%3\n"
  32                 "   slgr  %2,%3\n"
  33                 "   j     0b\n"
  34                 "2: la    %4,4095(%1)\n"/* %4 = ptr + 4095 */
  35                 "   nr    %4,%3\n"      /* %4 = (ptr + 4095) & -4096 */
  36                 "   slgr  %4,%1\n"
  37                 "   clgr  %0,%4\n"      /* copy crosses next page boundary? */
  38                 "   jnh   4f\n"
  39                 "3: .insn ss,0xc80000000000,0(%4,%2),0(%1),0\n"
  40                 "10:slgr  %0,%4\n"
  41                 "   algr  %2,%4\n"
  42                 "4: lghi  %4,-1\n"
  43                 "   algr  %4,%0\n"      /* copy remaining size, subtract 1 */
  44                 "   bras  %3,6f\n"      /* memset loop */
  45                 "   xc    0(1,%2),0(%2)\n"
  46                 "5: xc    0(256,%2),0(%2)\n"
  47                 "   la    %2,256(%2)\n"
  48                 "6: aghi  %4,-256\n"
  49                 "   jnm   5b\n"
  50                 "   ex    %4,0(%3)\n"
  51                 "   j     8f\n"
  52                 "7:slgr  %0,%0\n"
  53                 "8:\n"
  54                 EX_TABLE(0b,2b) EX_TABLE(3b,4b) EX_TABLE(9b,2b) EX_TABLE(10b,4b)
  55                 : "+a" (size), "+a" (ptr), "+a" (x), "+a" (tmp1), "=a" (tmp2)
  56                 : "d" (reg0) : "cc", "memory");
  57         return size;
  58 }
  59
  60 static inline unsigned long copy_from_user_mvcp(void *x, const void __user *ptr,
  61                                                 unsigned long size)
  62 {
  63         unsigned long tmp1, tmp2;
  64
  65         load_kernel_asce();
  66         tmp1 = -256UL;
  67         asm volatile(
  68                 "   sacf  0\n"
  69                 "0: mvcp  0(%0,%2),0(%1),%3\n"
  70                 "10:jz    8f\n"
  71                 "1: algr  %0,%3\n"
  72                 "   la    %1,256(%1)\n"
  73                 "   la    %2,256(%2)\n"
  74                 "2: mvcp  0(%0,%2),0(%1),%3\n"
  75                 "11:jnz   1b\n"
  76                 "   j     8f\n"
  77                 "3: la    %4,255(%1)\n" /* %4 = ptr + 255 */
  78                 "   lghi  %3,-4096\n"
  79                 "   nr    %4,%3\n"      /* %4 = (ptr + 255) & -4096 */
  80                 "   slgr  %4,%1\n"
  81                 "   clgr  %0,%4\n"      /* copy crosses next page boundary? */
  82                 "   jnh   5f\n"
  83                 "4: mvcp  0(%4,%2),0(%1),%3\n"
  84                 "12:slgr  %0,%4\n"
  85                 "   algr  %2,%4\n"
  86                 "5: lghi  %4,-1\n"
  87                 "   algr  %4,%0\n"      /* copy remaining size, subtract 1 */
  88                 "   bras  %3,7f\n"      /* memset loop */
  89                 "   xc    0(1,%2),0(%2)\n"
  90                 "6: xc    0(256,%2),0(%2)\n"
  91                 "   la    %2,256(%2)\n"
  92                 "7: aghi  %4,-256\n"
  93                 "   jnm   6b\n"
  94                 "   ex    %4,0(%3)\n"
  95                 "   j     9f\n"
  96                 "8:slgr  %0,%0\n"
  97                 "9: sacf  768\n"
  98                 EX_TABLE(0b,3b) EX_TABLE(2b,3b) EX_TABLE(4b,5b)
  99                 EX_TABLE(10b,3b) EX_TABLE(11b,3b) EX_TABLE(12b,5b)
 100                 : "+a" (size), "+a" (ptr), "+a" (x), "+a" (tmp1), "=a" (tmp2)
 101                 : : "cc", "memory");
 102         return size;
 103 }
 104
 105 unsigned long __copy_from_user(void *to, const void __user *from, unsigned long n)
 106 {
 107         if (static_key_false(&have_mvcos))
 108                 return copy_from_user_mvcos(to, from, n);
 109         return copy_from_user_mvcp(to, from, n);
 110 }
 111 EXPORT_SYMBOL(__copy_from_user);
 112
 113 static inline unsigned long copy_to_user_mvcos(void __user *ptr, const void *x,
 114                                                unsigned long size)
 115 {
 116         register unsigned long reg0 asm("0") = 0x810000UL;
 117         unsigned long tmp1, tmp2;
 118
 119         tmp1 = -4096UL;
 120         asm volatile(
 121                 "0: .insn ss,0xc80000000000,0(%0,%1),0(%2),0\n"
 122                 "6: jz    4f\n"
 123                 "1: algr  %0,%3\n"
 124                 "   slgr  %1,%3\n"
 125                 "   slgr  %2,%3\n"
 126                 "   j     0b\n"
 127                 "2: la    %4,4095(%1)\n"/* %4 = ptr + 4095 */
 128                 "   nr    %4,%3\n"      /* %4 = (ptr + 4095) & -4096 */
 129                 "   slgr  %4,%1\n"
 130                 "   clgr  %0,%4\n"      /* copy crosses next page boundary? */
 131                 "   jnh   5f\n"
 132                 "3: .insn ss,0xc80000000000,0(%4,%1),0(%2),0\n"
 133                 "7: slgr  %0,%4\n"
 134                 "   j     5f\n"
 135                 "4: slgr  %0,%0\n"
 136                 "5:\n"
 137                 EX_TABLE(0b,2b) EX_TABLE(3b,5b) EX_TABLE(6b,2b) EX_TABLE(7b,5b)
 138                 : "+a" (size), "+a" (ptr), "+a" (x), "+a" (tmp1), "=a" (tmp2)
 139                 : "d" (reg0) : "cc", "memory");
 140         return size;
 141 }
 142
 143 static inline unsigned long copy_to_user_mvcs(void __user *ptr, const void *x,
 144                                               unsigned long size)
 145 {
 146         unsigned long tmp1, tmp2;
 147
 148         load_kernel_asce();
 149         tmp1 = -256UL;
 150         asm volatile(
 151                 "   sacf  0\n"
 152                 "0: mvcs  0(%0,%1),0(%2),%3\n"
 153                 "7: jz    5f\n"
 154                 "1: algr  %0,%3\n"
 155                 "   la    %1,256(%1)\n"
 156                 "   la    %2,256(%2)\n"
 157                 "2: mvcs  0(%0,%1),0(%2),%3\n"
 158                 "8: jnz   1b\n"
 159                 "   j     5f\n"
 160                 "3: la    %4,255(%1)\n" /* %4 = ptr + 255 */
 161                 "   lghi  %3,-4096\n"
 162                 "   nr    %4,%3\n"      /* %4 = (ptr + 255) & -4096 */
 163                 "   slgr  %4,%1\n"
 164                 "   clgr  %0,%4\n"      /* copy crosses next page boundary? */
 165                 "   jnh   6f\n"
 166                 "4: mvcs  0(%4,%1),0(%2),%3\n"
 167                 "9: slgr  %0,%4\n"
 168                 "   j     6f\n"
 169                 "5: slgr  %0,%0\n"
 170                 "6: sacf  768\n"
 171                 EX_TABLE(0b,3b) EX_TABLE(2b,3b) EX_TABLE(4b,6b)
 172                 EX_TABLE(7b,3b) EX_TABLE(8b,3b) EX_TABLE(9b,6b)
 173                 : "+a" (size), "+a" (ptr), "+a" (x), "+a" (tmp1), "=a" (tmp2)
 174                 : : "cc", "memory");
 175         return size;
 176 }
 177
 178 unsigned long __copy_to_user(void __user *to, const void *from, unsigned long n)
 179 {
 180         if (static_key_false(&have_mvcos))
 181                 return copy_to_user_mvcos(to, from, n);
 182         return copy_to_user_mvcs(to, from, n);
 183 }
 184 EXPORT_SYMBOL(__copy_to_user);
 185
 186 static inline unsigned long copy_in_user_mvcos(void __user *to, const void __user *from,
 187                                                unsigned long size)
 188 {
 189         register unsigned long reg0 asm("0") = 0x810081UL;
 190         unsigned long tmp1, tmp2;
 191
 192         tmp1 = -4096UL;
 193         /* FIXME: copy with reduced length. */
 194         asm volatile(
 195                 "0: .insn ss,0xc80000000000,0(%0,%1),0(%2),0\n"
 196                 "   jz    2f\n"
 197                 "1: algr  %0,%3\n"
 198                 "   slgr  %1,%3\n"
 199                 "   slgr  %2,%3\n"
 200                 "   j     0b\n"
 201                 "2:slgr  %0,%0\n"
 202                 "3: \n"
 203                 EX_TABLE(0b,3b)
 204                 : "+a" (size), "+a" (to), "+a" (from), "+a" (tmp1), "=a" (tmp2)
 205                 : "d" (reg0) : "cc", "memory");
 206         return size;
 207 }
 208
 209 static inline unsigned long copy_in_user_mvc(void __user *to, const void __user *from,
 210                                              unsigned long size)
 211 {
 212         unsigned long tmp1;
 213
 214         load_kernel_asce();
 215         asm volatile(
 216                 "   sacf  256\n"
 217                 "   aghi  %0,-1\n"
 218                 "   jo    5f\n"
 219                 "   bras  %3,3f\n"
 220                 "0: aghi  %0,257\n"
 221                 "1: mvc   0(1,%1),0(%2)\n"
 222                 "   la    %1,1(%1)\n"
 223                 "   la    %2,1(%2)\n"
 224                 "   aghi  %0,-1\n"
 225                 "   jnz   1b\n"
 226                 "   j     5f\n"
 227                 "2: mvc   0(256,%1),0(%2)\n"
 228                 "   la    %1,256(%1)\n"
 229                 "   la    %2,256(%2)\n"
 230                 "3: aghi  %0,-256\n"
 231                 "   jnm   2b\n"
 232                 "4: ex    %0,1b-0b(%3)\n"
 233                 "5: slgr  %0,%0\n"
 234                 "6: sacf  768\n"
 235                 EX_TABLE(1b,6b) EX_TABLE(2b,0b) EX_TABLE(4b,0b)
 236                 : "+a" (size), "+a" (to), "+a" (from), "=a" (tmp1)
 237                 : : "cc", "memory");
 238         return size;
 239 }
 240
 241 unsigned long __copy_in_user(void __user *to, const void __user *from, unsigned long n)
 242 {
 243         if (static_key_false(&have_mvcos))
 244                 return copy_in_user_mvcos(to, from, n);
 245         return copy_in_user_mvc(to, from, n);
 246 }
 247 EXPORT_SYMBOL(__copy_in_user);
 248
 249 static inline unsigned long clear_user_mvcos(void __user *to, unsigned long size)
 250 {
 251         register unsigned long reg0 asm("0") = 0x810000UL;
 252         unsigned long tmp1, tmp2;
 253
 254         tmp1 = -4096UL;
 255         asm volatile(
 256                 "0: .insn ss,0xc80000000000,0(%0,%1),0(%4),0\n"
 257                 "   jz    4f\n"
 258                 "1: algr  %0,%2\n"
 259                 "   slgr  %1,%2\n"
 260                 "   j     0b\n"
 261                 "2: la    %3,4095(%1)\n"/* %4 = to + 4095 */
 262                 "   nr    %3,%2\n"      /* %4 = (to + 4095) & -4096 */
 263                 "   slgr  %3,%1\n"
 264                 "   clgr  %0,%3\n"      /* copy crosses next page boundary? */
 265                 "   jnh   5f\n"
 266                 "3: .insn ss,0xc80000000000,0(%3,%1),0(%4),0\n"
 267                 "   slgr  %0,%3\n"
 268                 "   j     5f\n"
 269                 "4:slgr  %0,%0\n"
 270                 "5:\n"
 271                 EX_TABLE(0b,2b) EX_TABLE(3b,5b)
 272                 : "+a" (size), "+a" (to), "+a" (tmp1), "=a" (tmp2)
 273                 : "a" (empty_zero_page), "d" (reg0) : "cc", "memory");
 274         return size;
 275 }
 276
 277 static inline unsigned long clear_user_xc(void __user *to, unsigned long size)
 278 {
 279         unsigned long tmp1, tmp2;
 280
 281         load_kernel_asce();
 282         asm volatile(
 283                 "   sacf  256\n"
 284                 "   aghi  %0,-1\n"
 285                 "   jo    5f\n"
 286                 "   bras  %3,3f\n"
 287                 "   xc    0(1,%1),0(%1)\n"
 288                 "0: aghi  %0,257\n"
 289                 "   la    %2,255(%1)\n" /* %2 = ptr + 255 */
 290                 "   srl   %2,12\n"
 291                 "   sll   %2,12\n"      /* %2 = (ptr + 255) & -4096 */
 292                 "   slgr  %2,%1\n"
 293                 "   clgr  %0,%2\n"      /* clear crosses next page boundary? */
 294                 "   jnh   5f\n"
 295                 "   aghi  %2,-1\n"
 296                 "1: ex    %2,0(%3)\n"
 297                 "   aghi  %2,1\n"
 298                 "   slgr  %0,%2\n"
 299                 "   j     5f\n"
 300                 "2: xc    0(256,%1),0(%1)\n"
 301                 "   la    %1,256(%1)\n"
 302                 "3: aghi  %0,-256\n"
 303                 "   jnm   2b\n"
 304                 "4: ex    %0,0(%3)\n"
 305                 "5: slgr  %0,%0\n"
 306                 "6: sacf  768\n"
 307                 EX_TABLE(1b,6b) EX_TABLE(2b,0b) EX_TABLE(4b,0b)
 308                 : "+a" (size), "+a" (to), "=a" (tmp1), "=a" (tmp2)
 309                 : : "cc", "memory");
 310         return size;
 311 }
 312
 313 unsigned long __clear_user(void __user *to, unsigned long size)
 314 {
 315         if (static_key_false(&have_mvcos))
 316                         return clear_user_mvcos(to, size);
 317         return clear_user_xc(to, size);
 318 }
 319 EXPORT_SYMBOL(__clear_user);
 320
 321 static inline unsigned long strnlen_user_srst(const char __user *src,
 322                                               unsigned long size)
 323 {
 324         register unsigned long reg0 asm("0") = 0;
 325         unsigned long tmp1, tmp2;
 326
 327         asm volatile(
 328                 "   la    %2,0(%1)\n"
 329                 "   la    %3,0(%0,%1)\n"
 330                 "   slgr  %0,%0\n"
 331                 "   sacf  256\n"
 332                 "0: srst  %3,%2\n"
 333                 "   jo    0b\n"
 334                 "   la    %0,1(%3)\n"   /* strnlen_user results includes \0 */
 335                 "   slgr  %0,%1\n"
 336                 "1: sacf  768\n"
 337                 EX_TABLE(0b,1b)
 338                 : "+a" (size), "+a" (src), "=a" (tmp1), "=a" (tmp2)
 339                 : "d" (reg0) : "cc", "memory");
 340         return size;
 341 }
 342
 343 unsigned long __strnlen_user(const char __user *src, unsigned long size)
 344 {
 345         if (unlikely(!size))
 346                 return 0;
 347         load_kernel_asce();
 348         return strnlen_user_srst(src, size);
 349 }
 350 EXPORT_SYMBOL(__strnlen_user);
 351
 352 long __strncpy_from_user(char *dst, const char __user *src, long size)
 353 {
 354         size_t done, len, offset, len_str;
 355
 356         if (unlikely(size <= 0))
 357                 return 0;
 358         done = 0;
 359         do {
 360                 offset = (size_t)src & ~PAGE_MASK;
 361                 len = min(size - done, PAGE_SIZE - offset);
 362                 if (copy_from_user(dst, src, len))
 363                         return -EFAULT;
 364                 len_str = strnlen(dst, len);
 365                 done += len_str;
 366                 src += len_str;
 367                 dst += len_str;
 368         } while ((len_str == len) && (done < size));
 369         return done;
 370 }
 371 EXPORT_SYMBOL(__strncpy_from_user);
 372
 373 /*
 374  * The "old" uaccess variant without mvcos can be enforced with the
 375  * uaccess_primary kernel parameter. This is mainly for debugging purposes.
 376  */
 377 static int uaccess_primary __initdata;
 378
 379 static int __init parse_uaccess_pt(char *__unused)
 380 {
 381         uaccess_primary = 1;
 382         return 0;
 383 }
 384 early_param("uaccess_primary", parse_uaccess_pt);
 385
 386 static int __init uaccess_init(void)
 387 {
 388         if (!uaccess_primary && test_facility(27))
 389                 static_key_slow_inc(&have_mvcos);
 390         return 0;
 391 }
 392 early_initcall(uaccess_init);