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 (schwidefsky@de.ibm.com),
   8  *               Gerald Schaefer (gerald.schaefer@de.ibm.com)
   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         unsigned long flags;
  68
  69         old_fs = current->thread.mm_segment;
  70         if (old_fs & 1)
  71                 return old_fs;
  72         /* protect against a concurrent page table upgrade */
  73         local_irq_save(flags);
  74         current->thread.mm_segment |= 1;
  75         asce = S390_lowcore.kernel_asce;
  76         if (likely(old_fs == USER_DS)) {
  77                 __ctl_store(cr, 1, 1);
  78                 if (cr != S390_lowcore.kernel_asce) {
  79                         __ctl_load(S390_lowcore.kernel_asce, 1, 1);
  80                         set_cpu_flag(CIF_ASCE_PRIMARY);
  81                 }
  82                 asce = S390_lowcore.user_asce;
  83         }
  84         __ctl_store(cr, 7, 7);
  85         if (cr != asce) {
  86                 __ctl_load(asce, 7, 7);
  87                 set_cpu_flag(CIF_ASCE_SECONDARY);
  88         }
  89         local_irq_restore(flags);
  90         return old_fs;
  91 }
  92 EXPORT_SYMBOL(enable_sacf_uaccess);
  93
  94 void disable_sacf_uaccess(mm_segment_t old_fs)
  95 {
  96         current->thread.mm_segment = old_fs;
  97         if (old_fs == USER_DS && test_facility(27)) {
  98                 __ctl_load(S390_lowcore.user_asce, 1, 1);
  99                 clear_cpu_flag(CIF_ASCE_PRIMARY);
 100         }
 101 }
 102 EXPORT_SYMBOL(disable_sacf_uaccess);
 103
 104 static inline unsigned long copy_from_user_mvcos(void *x, const void __user *ptr,
 105                                                  unsigned long size)
 106 {
 107         register unsigned long reg0 asm("0") = 0x01UL;
 108         unsigned long tmp1, tmp2;
 109
 110         tmp1 = -4096UL;
 111         asm volatile(
 112                 "0: .insn ss,0xc80000000000,0(%0,%2),0(%1),0\n"
 113                 "6: jz    4f\n"
 114                 "1: algr  %0,%3\n"
 115                 "   slgr  %1,%3\n"
 116                 "   slgr  %2,%3\n"
 117                 "   j     0b\n"
 118                 "2: la    %4,4095(%1)\n"/* %4 = ptr + 4095 */
 119                 "   nr    %4,%3\n"      /* %4 = (ptr + 4095) & -4096 */
 120                 "   slgr  %4,%1\n"
 121                 "   clgr  %0,%4\n"      /* copy crosses next page boundary? */
 122                 "   jnh   5f\n"
 123                 "3: .insn ss,0xc80000000000,0(%4,%2),0(%1),0\n"
 124                 "7: slgr  %0,%4\n"
 125                 "   j     5f\n"
 126                 "4: slgr  %0,%0\n"
 127                 "5:\n"
 128                 EX_TABLE(0b,2b) EX_TABLE(3b,5b) EX_TABLE(6b,2b) EX_TABLE(7b,5b)
 129                 : "+a" (size), "+a" (ptr), "+a" (x), "+a" (tmp1), "=a" (tmp2)
 130                 : "d" (reg0) : "cc", "memory");
 131         return size;
 132 }
 133
 134 static inline unsigned long copy_from_user_mvcp(void *x, const void __user *ptr,
 135                                                 unsigned long size)
 136 {
 137         unsigned long tmp1, tmp2;
 138         mm_segment_t old_fs;
 139
 140         old_fs = enable_sacf_uaccess();
 141         tmp1 = -256UL;
 142         asm volatile(
 143                 "   sacf  0\n"
 144                 "0: mvcp  0(%0,%2),0(%1),%3\n"
 145                 "7: jz    5f\n"
 146                 "1: algr  %0,%3\n"
 147                 "   la    %1,256(%1)\n"
 148                 "   la    %2,256(%2)\n"
 149                 "2: mvcp  0(%0,%2),0(%1),%3\n"
 150                 "8: jnz   1b\n"
 151                 "   j     5f\n"
 152                 "3: la    %4,255(%1)\n" /* %4 = ptr + 255 */
 153                 "   lghi  %3,-4096\n"
 154                 "   nr    %4,%3\n"      /* %4 = (ptr + 255) & -4096 */
 155                 "   slgr  %4,%1\n"
 156                 "   clgr  %0,%4\n"      /* copy crosses next page boundary? */
 157                 "   jnh   6f\n"
 158                 "4: mvcp  0(%4,%2),0(%1),%3\n"
 159                 "9: slgr  %0,%4\n"
 160                 "   j     6f\n"
 161                 "5: slgr  %0,%0\n"
 162                 "6: sacf  768\n"
 163                 EX_TABLE(0b,3b) EX_TABLE(2b,3b) EX_TABLE(4b,6b)
 164                 EX_TABLE(7b,3b) EX_TABLE(8b,3b) EX_TABLE(9b,6b)
 165                 : "+a" (size), "+a" (ptr), "+a" (x), "+a" (tmp1), "=a" (tmp2)
 166                 : : "cc", "memory");
 167         disable_sacf_uaccess(old_fs);
 168         return size;
 169 }
 170
 171 unsigned long raw_copy_from_user(void *to, const void __user *from, unsigned long n)
 172 {
 173         if (copy_with_mvcos())
 174                 return copy_from_user_mvcos(to, from, n);
 175         return copy_from_user_mvcp(to, from, n);
 176 }
 177 EXPORT_SYMBOL(raw_copy_from_user);
 178
 179 static inline unsigned long copy_to_user_mvcos(void __user *ptr, const void *x,
 180                                                unsigned long size)
 181 {
 182         register unsigned long reg0 asm("0") = 0x010000UL;
 183         unsigned long tmp1, tmp2;
 184
 185         tmp1 = -4096UL;
 186         asm volatile(
 187                 "0: .insn ss,0xc80000000000,0(%0,%1),0(%2),0\n"
 188                 "6: jz    4f\n"
 189                 "1: algr  %0,%3\n"
 190                 "   slgr  %1,%3\n"
 191                 "   slgr  %2,%3\n"
 192                 "   j     0b\n"
 193                 "2: la    %4,4095(%1)\n"/* %4 = ptr + 4095 */
 194                 "   nr    %4,%3\n"      /* %4 = (ptr + 4095) & -4096 */
 195                 "   slgr  %4,%1\n"
 196                 "   clgr  %0,%4\n"      /* copy crosses next page boundary? */
 197                 "   jnh   5f\n"
 198                 "3: .insn ss,0xc80000000000,0(%4,%1),0(%2),0\n"
 199                 "7: slgr  %0,%4\n"
 200                 "   j     5f\n"
 201                 "4: slgr  %0,%0\n"
 202                 "5:\n"
 203                 EX_TABLE(0b,2b) EX_TABLE(3b,5b) EX_TABLE(6b,2b) EX_TABLE(7b,5b)
 204                 : "+a" (size), "+a" (ptr), "+a" (x), "+a" (tmp1), "=a" (tmp2)
 205                 : "d" (reg0) : "cc", "memory");
 206         return size;
 207 }
 208
 209 static inline unsigned long copy_to_user_mvcs(void __user *ptr, const void *x,
 210                                               unsigned long size)
 211 {
 212         unsigned long tmp1, tmp2;
 213         mm_segment_t old_fs;
 214
 215         old_fs = enable_sacf_uaccess();
 216         tmp1 = -256UL;
 217         asm volatile(
 218                 "   sacf  0\n"
 219                 "0: mvcs  0(%0,%1),0(%2),%3\n"
 220                 "7: jz    5f\n"
 221                 "1: algr  %0,%3\n"
 222                 "   la    %1,256(%1)\n"
 223                 "   la    %2,256(%2)\n"
 224                 "2: mvcs  0(%0,%1),0(%2),%3\n"
 225                 "8: jnz   1b\n"
 226                 "   j     5f\n"
 227                 "3: la    %4,255(%1)\n" /* %4 = ptr + 255 */
 228                 "   lghi  %3,-4096\n"
 229                 "   nr    %4,%3\n"      /* %4 = (ptr + 255) & -4096 */
 230                 "   slgr  %4,%1\n"
 231                 "   clgr  %0,%4\n"      /* copy crosses next page boundary? */
 232                 "   jnh   6f\n"
 233                 "4: mvcs  0(%4,%1),0(%2),%3\n"
 234                 "9: slgr  %0,%4\n"
 235                 "   j     6f\n"
 236                 "5: slgr  %0,%0\n"
 237                 "6: sacf  768\n"
 238                 EX_TABLE(0b,3b) EX_TABLE(2b,3b) EX_TABLE(4b,6b)
 239                 EX_TABLE(7b,3b) EX_TABLE(8b,3b) EX_TABLE(9b,6b)
 240                 : "+a" (size), "+a" (ptr), "+a" (x), "+a" (tmp1), "=a" (tmp2)
 241                 : : "cc", "memory");
 242         disable_sacf_uaccess(old_fs);
 243         return size;
 244 }
 245
 246 unsigned long raw_copy_to_user(void __user *to, const void *from, unsigned long n)
 247 {
 248         if (copy_with_mvcos())
 249                 return copy_to_user_mvcos(to, from, n);
 250         return copy_to_user_mvcs(to, from, n);
 251 }
 252 EXPORT_SYMBOL(raw_copy_to_user);
 253
 254 static inline unsigned long copy_in_user_mvcos(void __user *to, const void __user *from,
 255                                                unsigned long size)
 256 {
 257         register unsigned long reg0 asm("0") = 0x010001UL;
 258         unsigned long tmp1, tmp2;
 259
 260         tmp1 = -4096UL;
 261         /* FIXME: copy with reduced length. */
 262         asm volatile(
 263                 "0: .insn ss,0xc80000000000,0(%0,%1),0(%2),0\n"
 264                 "   jz    2f\n"
 265                 "1: algr  %0,%3\n"
 266                 "   slgr  %1,%3\n"
 267                 "   slgr  %2,%3\n"
 268                 "   j     0b\n"
 269                 "2:slgr  %0,%0\n"
 270                 "3: \n"
 271                 EX_TABLE(0b,3b)
 272                 : "+a" (size), "+a" (to), "+a" (from), "+a" (tmp1), "=a" (tmp2)
 273                 : "d" (reg0) : "cc", "memory");
 274         return size;
 275 }
 276
 277 static inline unsigned long copy_in_user_mvc(void __user *to, const void __user *from,
 278                                              unsigned long size)
 279 {
 280         mm_segment_t old_fs;
 281         unsigned long tmp1;
 282
 283         old_fs = enable_sacf_uaccess();
 284         asm volatile(
 285                 "   sacf  256\n"
 286                 "   aghi  %0,-1\n"
 287                 "   jo    5f\n"
 288                 "   bras  %3,3f\n"
 289                 "0: aghi  %0,257\n"
 290                 "1: mvc   0(1,%1),0(%2)\n"
 291                 "   la    %1,1(%1)\n"
 292                 "   la    %2,1(%2)\n"
 293                 "   aghi  %0,-1\n"
 294                 "   jnz   1b\n"
 295                 "   j     5f\n"
 296                 "2: mvc   0(256,%1),0(%2)\n"
 297                 "   la    %1,256(%1)\n"
 298                 "   la    %2,256(%2)\n"
 299                 "3: aghi  %0,-256\n"
 300                 "   jnm   2b\n"
 301                 "4: ex    %0,1b-0b(%3)\n"
 302                 "5: slgr  %0,%0\n"
 303                 "6: sacf  768\n"
 304                 EX_TABLE(1b,6b) EX_TABLE(2b,0b) EX_TABLE(4b,0b)
 305                 : "+a" (size), "+a" (to), "+a" (from), "=a" (tmp1)
 306                 : : "cc", "memory");
 307         disable_sacf_uaccess(old_fs);
 308         return size;
 309 }
 310
 311 unsigned long raw_copy_in_user(void __user *to, const void __user *from, unsigned long n)
 312 {
 313         if (copy_with_mvcos())
 314                 return copy_in_user_mvcos(to, from, n);
 315         return copy_in_user_mvc(to, from, n);
 316 }
 317 EXPORT_SYMBOL(raw_copy_in_user);
 318
 319 static inline unsigned long clear_user_mvcos(void __user *to, unsigned long size)
 320 {
 321         register unsigned long reg0 asm("0") = 0x010000UL;
 322         unsigned long tmp1, tmp2;
 323
 324         tmp1 = -4096UL;
 325         asm volatile(
 326                 "0: .insn ss,0xc80000000000,0(%0,%1),0(%4),0\n"
 327                 "   jz    4f\n"
 328                 "1: algr  %0,%2\n"
 329                 "   slgr  %1,%2\n"
 330                 "   j     0b\n"
 331                 "2: la    %3,4095(%1)\n"/* %4 = to + 4095 */
 332                 "   nr    %3,%2\n"      /* %4 = (to + 4095) & -4096 */
 333                 "   slgr  %3,%1\n"
 334                 "   clgr  %0,%3\n"      /* copy crosses next page boundary? */
 335                 "   jnh   5f\n"
 336                 "3: .insn ss,0xc80000000000,0(%3,%1),0(%4),0\n"
 337                 "   slgr  %0,%3\n"
 338                 "   j     5f\n"
 339                 "4: slgr  %0,%0\n"
 340                 "5:\n"
 341                 EX_TABLE(0b,2b) EX_TABLE(3b,5b)
 342                 : "+a" (size), "+a" (to), "+a" (tmp1), "=a" (tmp2)
 343                 : "a" (empty_zero_page), "d" (reg0) : "cc", "memory");
 344         return size;
 345 }
 346
 347 static inline unsigned long clear_user_xc(void __user *to, unsigned long size)
 348 {
 349         mm_segment_t old_fs;
 350         unsigned long tmp1, tmp2;
 351
 352         old_fs = enable_sacf_uaccess();
 353         asm volatile(
 354                 "   sacf  256\n"
 355                 "   aghi  %0,-1\n"
 356                 "   jo    5f\n"
 357                 "   bras  %3,3f\n"
 358                 "   xc    0(1,%1),0(%1)\n"
 359                 "0: aghi  %0,257\n"
 360                 "   la    %2,255(%1)\n" /* %2 = ptr + 255 */
 361                 "   srl   %2,12\n"
 362                 "   sll   %2,12\n"      /* %2 = (ptr + 255) & -4096 */
 363                 "   slgr  %2,%1\n"
 364                 "   clgr  %0,%2\n"      /* clear crosses next page boundary? */
 365                 "   jnh   5f\n"
 366                 "   aghi  %2,-1\n"
 367                 "1: ex    %2,0(%3)\n"
 368                 "   aghi  %2,1\n"
 369                 "   slgr  %0,%2\n"
 370                 "   j     5f\n"
 371                 "2: xc    0(256,%1),0(%1)\n"
 372                 "   la    %1,256(%1)\n"
 373                 "3: aghi  %0,-256\n"
 374                 "   jnm   2b\n"
 375                 "4: ex    %0,0(%3)\n"
 376                 "5: slgr  %0,%0\n"
 377                 "6: sacf  768\n"
 378                 EX_TABLE(1b,6b) EX_TABLE(2b,0b) EX_TABLE(4b,0b)
 379                 : "+a" (size), "+a" (to), "=a" (tmp1), "=a" (tmp2)
 380                 : : "cc", "memory");
 381         disable_sacf_uaccess(old_fs);
 382         return size;
 383 }
 384
 385 unsigned long __clear_user(void __user *to, unsigned long size)
 386 {
 387         if (copy_with_mvcos())
 388                         return clear_user_mvcos(to, size);
 389         return clear_user_xc(to, size);
 390 }
 391 EXPORT_SYMBOL(__clear_user);
 392
 393 static inline unsigned long strnlen_user_srst(const char __user *src,
 394                                               unsigned long size)
 395 {
 396         register unsigned long reg0 asm("0") = 0;
 397         unsigned long tmp1, tmp2;
 398
 399         asm volatile(
 400                 "   la    %2,0(%1)\n"
 401                 "   la    %3,0(%0,%1)\n"
 402                 "   slgr  %0,%0\n"
 403                 "   sacf  256\n"
 404                 "0: srst  %3,%2\n"
 405                 "   jo    0b\n"
 406                 "   la    %0,1(%3)\n"   /* strnlen_user results includes \0 */
 407                 "   slgr  %0,%1\n"
 408                 "1: sacf  768\n"
 409                 EX_TABLE(0b,1b)
 410                 : "+a" (size), "+a" (src), "=a" (tmp1), "=a" (tmp2)
 411                 : "d" (reg0) : "cc", "memory");
 412         return size;
 413 }
 414
 415 unsigned long __strnlen_user(const char __user *src, unsigned long size)
 416 {
 417         mm_segment_t old_fs;
 418         unsigned long len;
 419
 420         if (unlikely(!size))
 421                 return 0;
 422         old_fs = enable_sacf_uaccess();
 423         len = strnlen_user_srst(src, size);
 424         disable_sacf_uaccess(old_fs);
 425         return len;
 426 }
 427 EXPORT_SYMBOL(__strnlen_user);
 428
 429 long __strncpy_from_user(char *dst, const char __user *src, long size)
 430 {
 431         size_t done, len, offset, len_str;
 432
 433         if (unlikely(size <= 0))
 434                 return 0;
 435         done = 0;
 436         do {
 437                 offset = (size_t)src & (L1_CACHE_BYTES - 1);
 438                 len = min(size - done, L1_CACHE_BYTES - offset);
 439                 if (copy_from_user(dst, src, len))
 440                         return -EFAULT;
 441                 len_str = strnlen(dst, len);
 442                 done += len_str;
 443                 src += len_str;
 444                 dst += len_str;
 445         } while ((len_str == len) && (done < size));
 446         return done;
 447 }
 448 EXPORT_SYMBOL(__strncpy_from_user);