arch/s390/lib/uaccess.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  *  Standard user space access functions based on mvcp/mvcs and doing
   4  *  interesting things in the secondary space mode.
   5  *
   6  *    Copyright IBM Corp. 2006,2014
   7  *    Author(s): Martin Schwidefsky ([email protected]),
   8  *               Gerald Schaefer ([email protected])
   9  */
  10
  11 #include <linux/jump_label.h>
  12 #include <linux/uaccess.h>
  13 #include <linux/export.h>
  14 #include <linux/errno.h>
  15 #include <linux/mm.h>
  16 #include <asm/mmu_context.h>
  17 #include <asm/facility.h>
  18
  19 #ifndef CONFIG_HAVE_MARCH_Z10_FEATURES
  20 static DEFINE_STATIC_KEY_FALSE(have_mvcos);
  21
  22 static int __init uaccess_init(void)
  23 {
  24         if (test_facility(27))
  25                 static_branch_enable(&have_mvcos);
  26         return 0;
  27 }
  28 early_initcall(uaccess_init);
  29
  30 static inline int copy_with_mvcos(void)
  31 {
  32         if (static_branch_likely(&have_mvcos))
  33                 return 1;
  34         return 0;
  35 }
  36 #else
  37 static inline int copy_with_mvcos(void)
  38 {
  39         return 1;
  40 }
  41 #endif
  42
  43 void set_fs(mm_segment_t fs)
  44 {
  45         current->thread.mm_segment = fs;
  46         if (fs == USER_DS) {
  47                 __ctl_load(S390_lowcore.user_asce, 1, 1);
  48                 clear_cpu_flag(CIF_ASCE_PRIMARY);
  49         } else {
  50                 __ctl_load(S390_lowcore.kernel_asce, 1, 1);
  51                 set_cpu_flag(CIF_ASCE_PRIMARY);
  52         }
  53         if (fs & 1) {
  54                 if (fs == USER_DS_SACF)
  55                         __ctl_load(S390_lowcore.user_asce, 7, 7);
  56                 else
  57                         __ctl_load(S390_lowcore.kernel_asce, 7, 7);
  58                 set_cpu_flag(CIF_ASCE_SECONDARY);
  59         }
  60 }
  61 EXPORT_SYMBOL(set_fs);
  62
  63 mm_segment_t enable_sacf_uaccess(void)
  64 {
  65         mm_segment_t old_fs;
  66         unsigned long asce, cr;
  67
  68         old_fs = current->thread.mm_segment;
  69         if (old_fs & 1)
  70                 return old_fs;
  71         current->thread.mm_segment |= 1;
  72         asce = S390_lowcore.kernel_asce;
  73         if (likely(old_fs == USER_DS)) {
  74                 __ctl_store(cr, 1, 1);
  75                 if (cr != S390_lowcore.kernel_asce) {
  76                         __ctl_load(S390_lowcore.kernel_asce, 1, 1);
  77                         set_cpu_flag(CIF_ASCE_PRIMARY);
  78                 }
  79                 asce = S390_lowcore.user_asce;
  80         }
  81         __ctl_store(cr, 7, 7);
  82         if (cr != asce) {
  83                 __ctl_load(asce, 7, 7);
  84                 set_cpu_flag(CIF_ASCE_SECONDARY);
  85         }
  86         return old_fs;
  87 }
  88 EXPORT_SYMBOL(enable_sacf_uaccess);
  89
  90 void disable_sacf_uaccess(mm_segment_t old_fs)
  91 {
  92         current->thread.mm_segment = old_fs;
  93         if (old_fs == USER_DS && test_facility(27)) {
  94                 __ctl_load(S390_lowcore.user_asce, 1, 1);
  95                 clear_cpu_flag(CIF_ASCE_PRIMARY);
  96         }
  97 }
  98 EXPORT_SYMBOL(disable_sacf_uaccess);
  99
 100 static inline unsigned long copy_from_user_mvcos(void *x, const void __user *ptr,
 101                                                  unsigned long size)
 102 {
 103         register unsigned long reg0 asm("0") = 0x01UL;
 104         unsigned long tmp1, tmp2;
 105
 106         tmp1 = -4096UL;
 107         asm volatile(
 108                 "0: .insn ss,0xc80000000000,0(%0,%2),0(%1),0\n"
 109                 "6: jz    4f\n"
 110                 "1: algr  %0,%3\n"
 111                 "   slgr  %1,%3\n"
 112                 "   slgr  %2,%3\n"
 113                 "   j     0b\n"
 114                 "2: la    %4,4095(%1)\n"/* %4 = ptr + 4095 */
 115                 "   nr    %4,%3\n"      /* %4 = (ptr + 4095) & -4096 */
 116                 "   slgr  %4,%1\n"
 117                 "   clgr  %0,%4\n"      /* copy crosses next page boundary? */
 118                 "   jnh   5f\n"
 119                 "3: .insn ss,0xc80000000000,0(%4,%2),0(%1),0\n"
 120                 "7: slgr  %0,%4\n"
 121                 "   j     5f\n"
 122                 "4: slgr  %0,%0\n"
 123                 "5:\n"
 124                 EX_TABLE(0b,2b) EX_TABLE(3b,5b) EX_TABLE(6b,2b) EX_TABLE(7b,5b)
 125                 : "+a" (size), "+a" (ptr), "+a" (x), "+a" (tmp1), "=a" (tmp2)
 126                 : "d" (reg0) : "cc", "memory");
 127         return size;
 128 }
 129
 130 static inline unsigned long copy_from_user_mvcp(void *x, const void __user *ptr,
 131                                                 unsigned long size)
 132 {
 133         unsigned long tmp1, tmp2;
 134         mm_segment_t old_fs;
 135
 136         old_fs = enable_sacf_uaccess();
 137         tmp1 = -256UL;
 138         asm volatile(
 139                 "   sacf  0\n"
 140                 "0: mvcp  0(%0,%2),0(%1),%3\n"
 141                 "7: jz    5f\n"
 142                 "1: algr  %0,%3\n"
 143                 "   la    %1,256(%1)\n"
 144                 "   la    %2,256(%2)\n"
 145                 "2: mvcp  0(%0,%2),0(%1),%3\n"
 146                 "8: jnz   1b\n"
 147                 "   j     5f\n"
 148                 "3: la    %4,255(%1)\n" /* %4 = ptr + 255 */
 149                 "   lghi  %3,-4096\n"
 150                 "   nr    %4,%3\n"      /* %4 = (ptr + 255) & -4096 */
 151                 "   slgr  %4,%1\n"
 152                 "   clgr  %0,%4\n"      /* copy crosses next page boundary? */
 153                 "   jnh   6f\n"
 154                 "4: mvcp  0(%4,%2),0(%1),%3\n"
 155                 "9: slgr  %0,%4\n"
 156                 "   j     6f\n"
 157                 "5: slgr  %0,%0\n"
 158                 "6: sacf  768\n"
 159                 EX_TABLE(0b,3b) EX_TABLE(2b,3b) EX_TABLE(4b,6b)
 160                 EX_TABLE(7b,3b) EX_TABLE(8b,3b) EX_TABLE(9b,6b)
 161                 : "+a" (size), "+a" (ptr), "+a" (x), "+a" (tmp1), "=a" (tmp2)
 162                 : : "cc", "memory");
 163         disable_sacf_uaccess(old_fs);
 164         return size;
 165 }
 166
 167 unsigned long raw_copy_from_user(void *to, const void __user *from, unsigned long n)
 168 {
 169         if (copy_with_mvcos())
 170                 return copy_from_user_mvcos(to, from, n);
 171         return copy_from_user_mvcp(to, from, n);
 172 }
 173 EXPORT_SYMBOL(raw_copy_from_user);
 174
 175 static inline unsigned long copy_to_user_mvcos(void __user *ptr, const void *x,
 176                                                unsigned long size)
 177 {
 178         register unsigned long reg0 asm("0") = 0x010000UL;
 179         unsigned long tmp1, tmp2;
 180
 181         tmp1 = -4096UL;
 182         asm volatile(
 183                 "0: .insn ss,0xc80000000000,0(%0,%1),0(%2),0\n"
 184                 "6: jz    4f\n"
 185                 "1: algr  %0,%3\n"
 186                 "   slgr  %1,%3\n"
 187                 "   slgr  %2,%3\n"
 188                 "   j     0b\n"
 189                 "2: la    %4,4095(%1)\n"/* %4 = ptr + 4095 */
 190                 "   nr    %4,%3\n"      /* %4 = (ptr + 4095) & -4096 */
 191                 "   slgr  %4,%1\n"
 192                 "   clgr  %0,%4\n"      /* copy crosses next page boundary? */
 193                 "   jnh   5f\n"
 194                 "3: .insn ss,0xc80000000000,0(%4,%1),0(%2),0\n"
 195                 "7: slgr  %0,%4\n"
 196                 "   j     5f\n"
 197                 "4: slgr  %0,%0\n"
 198                 "5:\n"
 199                 EX_TABLE(0b,2b) EX_TABLE(3b,5b) EX_TABLE(6b,2b) EX_TABLE(7b,5b)
 200                 : "+a" (size), "+a" (ptr), "+a" (x), "+a" (tmp1), "=a" (tmp2)
 201                 : "d" (reg0) : "cc", "memory");
 202         return size;
 203 }
 204
 205 static inline unsigned long copy_to_user_mvcs(void __user *ptr, const void *x,
 206                                               unsigned long size)
 207 {
 208         unsigned long tmp1, tmp2;
 209         mm_segment_t old_fs;
 210
 211         old_fs = enable_sacf_uaccess();
 212         tmp1 = -256UL;
 213         asm volatile(
 214                 "   sacf  0\n"
 215                 "0: mvcs  0(%0,%1),0(%2),%3\n"
 216                 "7: jz    5f\n"
 217                 "1: algr  %0,%3\n"
 218                 "   la    %1,256(%1)\n"
 219                 "   la    %2,256(%2)\n"
 220                 "2: mvcs  0(%0,%1),0(%2),%3\n"
 221                 "8: jnz   1b\n"
 222                 "   j     5f\n"
 223                 "3: la    %4,255(%1)\n" /* %4 = ptr + 255 */
 224                 "   lghi  %3,-4096\n"
 225                 "   nr    %4,%3\n"      /* %4 = (ptr + 255) & -4096 */
 226                 "   slgr  %4,%1\n"
 227                 "   clgr  %0,%4\n"      /* copy crosses next page boundary? */
 228                 "   jnh   6f\n"
 229                 "4: mvcs  0(%4,%1),0(%2),%3\n"
 230                 "9: slgr  %0,%4\n"
 231                 "   j     6f\n"
 232                 "5: slgr  %0,%0\n"
 233                 "6: sacf  768\n"
 234                 EX_TABLE(0b,3b) EX_TABLE(2b,3b) EX_TABLE(4b,6b)
 235                 EX_TABLE(7b,3b) EX_TABLE(8b,3b) EX_TABLE(9b,6b)
 236                 : "+a" (size), "+a" (ptr), "+a" (x), "+a" (tmp1), "=a" (tmp2)
 237                 : : "cc", "memory");
 238         disable_sacf_uaccess(old_fs);
 239         return size;
 240 }
 241
 242 unsigned long raw_copy_to_user(void __user *to, const void *from, unsigned long n)
 243 {
 244         if (copy_with_mvcos())
 245                 return copy_to_user_mvcos(to, from, n);
 246         return copy_to_user_mvcs(to, from, n);
 247 }
 248 EXPORT_SYMBOL(raw_copy_to_user);
 249
 250 static inline unsigned long copy_in_user_mvcos(void __user *to, const void __user *from,
 251                                                unsigned long size)
 252 {
 253         register unsigned long reg0 asm("0") = 0x010001UL;
 254         unsigned long tmp1, tmp2;
 255
 256         tmp1 = -4096UL;
 257         /* FIXME: copy with reduced length. */
 258         asm volatile(
 259                 "0: .insn ss,0xc80000000000,0(%0,%1),0(%2),0\n"
 260                 "   jz    2f\n"
 261                 "1: algr  %0,%3\n"
 262                 "   slgr  %1,%3\n"
 263                 "   slgr  %2,%3\n"
 264                 "   j     0b\n"
 265                 "2:slgr  %0,%0\n"
 266                 "3: \n"
 267                 EX_TABLE(0b,3b)
 268                 : "+a" (size), "+a" (to), "+a" (from), "+a" (tmp1), "=a" (tmp2)
 269                 : "d" (reg0) : "cc", "memory");
 270         return size;
 271 }
 272
 273 static inline unsigned long copy_in_user_mvc(void __user *to, const void __user *from,
 274                                              unsigned long size)
 275 {
 276         mm_segment_t old_fs;
 277         unsigned long tmp1;
 278
 279         old_fs = enable_sacf_uaccess();
 280         asm volatile(
 281                 "   sacf  256\n"
 282                 "   aghi  %0,-1\n"
 283                 "   jo    5f\n"
 284                 "   bras  %3,3f\n"
 285                 "0: aghi  %0,257\n"
 286                 "1: mvc   0(1,%1),0(%2)\n"
 287                 "   la    %1,1(%1)\n"
 288                 "   la    %2,1(%2)\n"
 289                 "   aghi  %0,-1\n"
 290                 "   jnz   1b\n"
 291                 "   j     5f\n"
 292                 "2: mvc   0(256,%1),0(%2)\n"
 293                 "   la    %1,256(%1)\n"
 294                 "   la    %2,256(%2)\n"
 295                 "3: aghi  %0,-256\n"
 296                 "   jnm   2b\n"
 297                 "4: ex    %0,1b-0b(%3)\n"
 298                 "5: slgr  %0,%0\n"
 299                 "6: sacf  768\n"
 300                 EX_TABLE(1b,6b) EX_TABLE(2b,0b) EX_TABLE(4b,0b)
 301                 : "+a" (size), "+a" (to), "+a" (from), "=a" (tmp1)
 302                 : : "cc", "memory");
 303         disable_sacf_uaccess(old_fs);
 304         return size;
 305 }
 306
 307 unsigned long raw_copy_in_user(void __user *to, const void __user *from, unsigned long n)
 308 {
 309         if (copy_with_mvcos())
 310                 return copy_in_user_mvcos(to, from, n);
 311         return copy_in_user_mvc(to, from, n);
 312 }
 313 EXPORT_SYMBOL(raw_copy_in_user);
 314
 315 static inline unsigned long clear_user_mvcos(void __user *to, unsigned long size)
 316 {
 317         register unsigned long reg0 asm("0") = 0x010000UL;
 318         unsigned long tmp1, tmp2;
 319
 320         tmp1 = -4096UL;
 321         asm volatile(
 322                 "0: .insn ss,0xc80000000000,0(%0,%1),0(%4),0\n"
 323                 "   jz    4f\n"
 324                 "1: algr  %0,%2\n"
 325                 "   slgr  %1,%2\n"
 326                 "   j     0b\n"
 327                 "2: la    %3,4095(%1)\n"/* %4 = to + 4095 */
 328                 "   nr    %3,%2\n"      /* %4 = (to + 4095) & -4096 */
 329                 "   slgr  %3,%1\n"
 330                 "   clgr  %0,%3\n"      /* copy crosses next page boundary? */
 331                 "   jnh   5f\n"
 332                 "3: .insn ss,0xc80000000000,0(%3,%1),0(%4),0\n"
 333                 "   slgr  %0,%3\n"
 334                 "   j     5f\n"
 335                 "4: slgr  %0,%0\n"
 336                 "5:\n"
 337                 EX_TABLE(0b,2b) EX_TABLE(3b,5b)
 338                 : "+a" (size), "+a" (to), "+a" (tmp1), "=a" (tmp2)
 339                 : "a" (empty_zero_page), "d" (reg0) : "cc", "memory");
 340         return size;
 341 }
 342
 343 static inline unsigned long clear_user_xc(void __user *to, unsigned long size)
 344 {
 345         mm_segment_t old_fs;
 346         unsigned long tmp1, tmp2;
 347
 348         old_fs = enable_sacf_uaccess();
 349         asm volatile(
 350                 "   sacf  256\n"
 351                 "   aghi  %0,-1\n"
 352                 "   jo    5f\n"
 353                 "   bras  %3,3f\n"
 354                 "   xc    0(1,%1),0(%1)\n"
 355                 "0: aghi  %0,257\n"
 356                 "   la    %2,255(%1)\n" /* %2 = ptr + 255 */
 357                 "   srl   %2,12\n"
 358                 "   sll   %2,12\n"      /* %2 = (ptr + 255) & -4096 */
 359                 "   slgr  %2,%1\n"
 360                 "   clgr  %0,%2\n"      /* clear crosses next page boundary? */
 361                 "   jnh   5f\n"
 362                 "   aghi  %2,-1\n"
 363                 "1: ex    %2,0(%3)\n"
 364                 "   aghi  %2,1\n"
 365                 "   slgr  %0,%2\n"
 366                 "   j     5f\n"
 367                 "2: xc    0(256,%1),0(%1)\n"
 368                 "   la    %1,256(%1)\n"
 369                 "3: aghi  %0,-256\n"
 370                 "   jnm   2b\n"
 371                 "4: ex    %0,0(%3)\n"
 372                 "5: slgr  %0,%0\n"
 373                 "6: sacf  768\n"
 374                 EX_TABLE(1b,6b) EX_TABLE(2b,0b) EX_TABLE(4b,0b)
 375                 : "+a" (size), "+a" (to), "=a" (tmp1), "=a" (tmp2)
 376                 : : "cc", "memory");
 377         disable_sacf_uaccess(old_fs);
 378         return size;
 379 }
 380
 381 unsigned long __clear_user(void __user *to, unsigned long size)
 382 {
 383         if (copy_with_mvcos())
 384                         return clear_user_mvcos(to, size);
 385         return clear_user_xc(to, size);
 386 }
 387 EXPORT_SYMBOL(__clear_user);
 388
 389 static inline unsigned long strnlen_user_srst(const char __user *src,
 390                                               unsigned long size)
 391 {
 392         register unsigned long reg0 asm("0") = 0;
 393         unsigned long tmp1, tmp2;
 394
 395         asm volatile(
 396                 "   la    %2,0(%1)\n"
 397                 "   la    %3,0(%0,%1)\n"
 398                 "   slgr  %0,%0\n"
 399                 "   sacf  256\n"
 400                 "0: srst  %3,%2\n"
 401                 "   jo    0b\n"
 402                 "   la    %0,1(%3)\n"   /* strnlen_user results includes \0 */
 403                 "   slgr  %0,%1\n"
 404                 "1: sacf  768\n"
 405                 EX_TABLE(0b,1b)
 406                 : "+a" (size), "+a" (src), "=a" (tmp1), "=a" (tmp2)
 407                 : "d" (reg0) : "cc", "memory");
 408         return size;
 409 }
 410
 411 unsigned long __strnlen_user(const char __user *src, unsigned long size)
 412 {
 413         mm_segment_t old_fs;
 414         unsigned long len;
 415
 416         if (unlikely(!size))
 417                 return 0;
 418         old_fs = enable_sacf_uaccess();
 419         len = strnlen_user_srst(src, size);
 420         disable_sacf_uaccess(old_fs);
 421         return len;
 422 }
 423 EXPORT_SYMBOL(__strnlen_user);
 424
 425 long __strncpy_from_user(char *dst, const char __user *src, long size)
 426 {
 427         size_t done, len, offset, len_str;
 428
 429         if (unlikely(size <= 0))
 430                 return 0;
 431         done = 0;
 432         do {
 433                 offset = (size_t)src & (L1_CACHE_BYTES - 1);
 434                 len = min(size - done, L1_CACHE_BYTES - offset);
 435                 if (copy_from_user(dst, src, len))
 436                         return -EFAULT;
 437                 len_str = strnlen(dst, len);
 438                 done += len_str;
 439                 src += len_str;
 440                 dst += len_str;
 441         } while ((len_str == len) && (done < size));
 442         return done;
 443 }
 444 EXPORT_SYMBOL(__strncpy_from_user);