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   1 /*
   2  *  linux/arch/arm/mm/alignment.c
   3  *
   4  *  Copyright (C) 1995  Linus Torvalds
   5  *  Modifications for ARM processor (c) 1995-2001 Russell King
   6  *  Thumb aligment fault fixups (c) 2004 MontaVista Software, Inc.
   7  *  - Adapted from gdb/sim/arm/thumbemu.c -- Thumb instruction emulation.
   8  *    Copyright (C) 1996, Cygnus Software Technologies Ltd.
   9  *
  10  * This program is free software; you can redistribute it and/or modify
  11  * it under the terms of the GNU General Public License version 2 as
  12  * published by the Free Software Foundation.
  13  */
  14 #include <linux/config.h>
  15 #include <linux/compiler.h>
  16 #include <linux/kernel.h>
  17 #include <linux/errno.h>
  18 #include <linux/string.h>
  19 #include <linux/ptrace.h>
  20 #include <linux/proc_fs.h>
  21 #include <linux/init.h>
  22
  23 #include <asm/uaccess.h>
  24 #include <asm/unaligned.h>
  25
  26 #include "fault.h"
  27
  28 /*
  29  * 32-bit misaligned trap handler (c) 1998 San Mehat (CCC) -July 1998
  30  * /proc/sys/debug/alignment, modified and integrated into
  31  * Linux 2.1 by Russell King
  32  *
  33  * Speed optimisations and better fault handling by Russell King.
  34  *
  35  * *** NOTE ***
  36  * This code is not portable to processors with late data abort handling.
  37  */
  38 #define CODING_BITS(i)  (i & 0x0e000000)
  39
  40 #define LDST_I_BIT(i)   (i & (1 << 26))         /* Immediate constant   */
  41 #define LDST_P_BIT(i)   (i & (1 << 24))         /* Preindex             */
  42 #define LDST_U_BIT(i)   (i & (1 << 23))         /* Add offset           */
  43 #define LDST_W_BIT(i)   (i & (1 << 21))         /* Writeback            */
  44 #define LDST_L_BIT(i)   (i & (1 << 20))         /* Load                 */
  45
  46 #define LDST_P_EQ_U(i)  ((((i) ^ ((i) >> 1)) & (1 << 23)) == 0)
  47
  48 #define LDSTH_I_BIT(i)  (i & (1 << 22))         /* half-word immed      */
  49 #define LDM_S_BIT(i)    (i & (1 << 22))         /* write CPSR from SPSR */
  50
  51 #define RN_BITS(i)      ((i >> 16) & 15)        /* Rn                   */
  52 #define RD_BITS(i)      ((i >> 12) & 15)        /* Rd                   */
  53 #define RM_BITS(i)      (i & 15)                /* Rm                   */
  54
  55 #define REGMASK_BITS(i) (i & 0xffff)
  56 #define OFFSET_BITS(i)  (i & 0x0fff)
  57
  58 #define IS_SHIFT(i)     (i & 0x0ff0)
  59 #define SHIFT_BITS(i)   ((i >> 7) & 0x1f)
  60 #define SHIFT_TYPE(i)   (i & 0x60)
  61 #define SHIFT_LSL       0x00
  62 #define SHIFT_LSR       0x20
  63 #define SHIFT_ASR       0x40
  64 #define SHIFT_RORRRX    0x60
  65
  66 static unsigned long ai_user;
  67 static unsigned long ai_sys;
  68 static unsigned long ai_skipped;
  69 static unsigned long ai_half;
  70 static unsigned long ai_word;
  71 static unsigned long ai_multi;
  72 static int ai_usermode;
  73
  74 #ifdef CONFIG_PROC_FS
  75 static const char *usermode_action[] = {
  76         "ignored",
  77         "warn",
  78         "fixup",
  79         "fixup+warn",
  80         "signal",
  81         "signal+warn"
  82 };
  83
  84 static int
  85 proc_alignment_read(char *page, char **start, off_t off, int count, int *eof,
  86                     void *data)
  87 {
  88         char *p = page;
  89         int len;
  90
  91         p += sprintf(p, "User:\t\t%lu\n", ai_user);
  92         p += sprintf(p, "System:\t\t%lu\n", ai_sys);
  93         p += sprintf(p, "Skipped:\t%lu\n", ai_skipped);
  94         p += sprintf(p, "Half:\t\t%lu\n", ai_half);
  95         p += sprintf(p, "Word:\t\t%lu\n", ai_word);
  96         p += sprintf(p, "Multi:\t\t%lu\n", ai_multi);
  97         p += sprintf(p, "User faults:\t%i (%s)\n", ai_usermode,
  98                         usermode_action[ai_usermode]);
  99
 100         len = (p - page) - off;
 101         if (len < 0)
 102                 len = 0;
 103
 104         *eof = (len <= count) ? 1 : 0;
 105         *start = page + off;
 106
 107         return len;
 108 }
 109
 110 static int proc_alignment_write(struct file *file, const char __user *buffer,
 111                                unsigned long count, void *data)
 112 {
 113         char mode;
 114
 115         if (count > 0) {
 116                 if (get_user(mode, buffer))
 117                         return -EFAULT;
 118                 if (mode >= '0' && mode <= '5')
 119                            ai_usermode = mode - '0';
 120         }
 121         return count;
 122 }
 123
 124 #endif /* CONFIG_PROC_FS */
 125
 126 union offset_union {
 127         unsigned long un;
 128           signed long sn;
 129 };
 130
 131 #define TYPE_ERROR      0
 132 #define TYPE_FAULT      1
 133 #define TYPE_LDST       2
 134 #define TYPE_DONE       3
 135
 136 #ifdef __ARMEB__
 137 #define BE              1
 138 #define FIRST_BYTE_16   "mov    %1, %1, ror #8\n"
 139 #define FIRST_BYTE_32   "mov    %1, %1, ror #24\n"
 140 #define NEXT_BYTE       "ror #24"
 141 #else
 142 #define BE              0
 143 #define FIRST_BYTE_16
 144 #define FIRST_BYTE_32
 145 #define NEXT_BYTE       "lsr #8"
 146 #endif
 147
 148 #define __get8_unaligned_check(ins,val,addr,err)        \
 149         __asm__(                                        \
 150         "1:     "ins"   %1, [%2], #1\n"                 \
 151         "2:\n"                                          \
 152         "       .section .fixup,\"ax\"\n"               \
 153         "       .align  2\n"                            \
 154         "3:     mov     %0, #1\n"                       \
 155         "       b       2b\n"                           \
 156         "       .previous\n"                            \
 157         "       .section __ex_table,\"a\"\n"            \
 158         "       .align  3\n"                            \
 159         "       .long   1b, 3b\n"                       \
 160         "       .previous\n"                            \
 161         : "=r" (err), "=&r" (val), "=r" (addr)          \
 162         : "0" (err), "2" (addr))
 163
 164 #define __get16_unaligned_check(ins,val,addr)                   \
 165         do {                                                    \
 166                 unsigned int err = 0, v, a = addr;              \
 167                 __get8_unaligned_check(ins,v,a,err);            \
 168                 val =  v << ((BE) ? 8 : 0);                     \
 169                 __get8_unaligned_check(ins,v,a,err);            \
 170                 val |= v << ((BE) ? 0 : 8);                     \
 171                 if (err)                                        \
 172                         goto fault;                             \
 173         } while (0)
 174
 175 #define get16_unaligned_check(val,addr) \
 176         __get16_unaligned_check("ldrb",val,addr)
 177
 178 #define get16t_unaligned_check(val,addr) \
 179         __get16_unaligned_check("ldrbt",val,addr)
 180
 181 #define __get32_unaligned_check(ins,val,addr)                   \
 182         do {                                                    \
 183                 unsigned int err = 0, v, a = addr;              \
 184                 __get8_unaligned_check(ins,v,a,err);            \
 185                 val =  v << ((BE) ? 24 :  0);                   \
 186                 __get8_unaligned_check(ins,v,a,err);            \
 187                 val |= v << ((BE) ? 16 :  8);                   \
 188                 __get8_unaligned_check(ins,v,a,err);            \
 189                 val |= v << ((BE) ?  8 : 16);                   \
 190                 __get8_unaligned_check(ins,v,a,err);            \
 191                 val |= v << ((BE) ?  0 : 24);                   \
 192                 if (err)                                        \
 193                         goto fault;                             \
 194         } while (0)
 195
 196 #define get32_unaligned_check(val,addr) \
 197         __get32_unaligned_check("ldrb",val,addr)
 198
 199 #define get32t_unaligned_check(val,addr) \
 200         __get32_unaligned_check("ldrbt",val,addr)
 201
 202 #define __put16_unaligned_check(ins,val,addr)                   \
 203         do {                                                    \
 204                 unsigned int err = 0, v = val, a = addr;        \
 205                 __asm__( FIRST_BYTE_16                          \
 206                 "1:     "ins"   %1, [%2], #1\n"                 \
 207                 "       mov     %1, %1, "NEXT_BYTE"\n"          \
 208                 "2:     "ins"   %1, [%2]\n"                     \
 209                 "3:\n"                                          \
 210                 "       .section .fixup,\"ax\"\n"               \
 211                 "       .align  2\n"                            \
 212                 "4:     mov     %0, #1\n"                       \
 213                 "       b       3b\n"                           \
 214                 "       .previous\n"                            \
 215                 "       .section __ex_table,\"a\"\n"            \
 216                 "       .align  3\n"                            \
 217                 "       .long   1b, 4b\n"                       \
 218                 "       .long   2b, 4b\n"                       \
 219                 "       .previous\n"                            \
 220                 : "=r" (err), "=&r" (v), "=&r" (a)              \
 221                 : "0" (err), "1" (v), "2" (a));                 \
 222                 if (err)                                        \
 223                         goto fault;                             \
 224         } while (0)
 225
 226 #define put16_unaligned_check(val,addr)  \
 227         __put16_unaligned_check("strb",val,addr)
 228
 229 #define put16t_unaligned_check(val,addr) \
 230         __put16_unaligned_check("strbt",val,addr)
 231
 232 #define __put32_unaligned_check(ins,val,addr)                   \
 233         do {                                                    \
 234                 unsigned int err = 0, v = val, a = addr;        \
 235                 __asm__( FIRST_BYTE_32                          \
 236                 "1:     "ins"   %1, [%2], #1\n"                 \
 237                 "       mov     %1, %1, "NEXT_BYTE"\n"          \
 238                 "2:     "ins"   %1, [%2], #1\n"                 \
 239                 "       mov     %1, %1, "NEXT_BYTE"\n"          \
 240                 "3:     "ins"   %1, [%2], #1\n"                 \
 241                 "       mov     %1, %1, "NEXT_BYTE"\n"          \
 242                 "4:     "ins"   %1, [%2]\n"                     \
 243                 "5:\n"                                          \
 244                 "       .section .fixup,\"ax\"\n"               \
 245                 "       .align  2\n"                            \
 246                 "6:     mov     %0, #1\n"                       \
 247                 "       b       5b\n"                           \
 248                 "       .previous\n"                            \
 249                 "       .section __ex_table,\"a\"\n"            \
 250                 "       .align  3\n"                            \
 251                 "       .long   1b, 6b\n"                       \
 252                 "       .long   2b, 6b\n"                       \
 253                 "       .long   3b, 6b\n"                       \
 254                 "       .long   4b, 6b\n"                       \
 255                 "       .previous\n"                            \
 256                 : "=r" (err), "=&r" (v), "=&r" (a)              \
 257                 : "0" (err), "1" (v), "2" (a));                 \
 258                 if (err)                                        \
 259                         goto fault;                             \
 260         } while (0)
 261
 262 #define put32_unaligned_check(val,addr)  \
 263         __put32_unaligned_check("strb", val, addr)
 264
 265 #define put32t_unaligned_check(val,addr) \
 266         __put32_unaligned_check("strbt", val, addr)
 267
 268 static void
 269 do_alignment_finish_ldst(unsigned long addr, unsigned long instr, struct pt_regs *regs, union offset_union offset)
 270 {
 271         if (!LDST_U_BIT(instr))
 272                 offset.un = -offset.un;
 273
 274         if (!LDST_P_BIT(instr))
 275                 addr += offset.un;
 276
 277         if (!LDST_P_BIT(instr) || LDST_W_BIT(instr))
 278                 regs->uregs[RN_BITS(instr)] = addr;
 279 }
 280
 281 static int
 282 do_alignment_ldrhstrh(unsigned long addr, unsigned long instr, struct pt_regs *regs)
 283 {
 284         unsigned int rd = RD_BITS(instr);
 285
 286         if ((instr & 0x01f00ff0) == 0x01000090)
 287                 goto swp;
 288
 289         if ((instr & 0x90) != 0x90 || (instr & 0x60) == 0)
 290                 goto bad;
 291
 292         ai_half += 1;
 293
 294         if (user_mode(regs))
 295                 goto user;
 296
 297         if (LDST_L_BIT(instr)) {
 298                 unsigned long val;
 299                 get16_unaligned_check(val, addr);
 300
 301                 /* signed half-word? */
 302                 if (instr & 0x40)
 303                         val = (signed long)((signed short) val);
 304
 305                 regs->uregs[rd] = val;
 306         } else
 307                 put16_unaligned_check(regs->uregs[rd], addr);
 308
 309         return TYPE_LDST;
 310
 311  user:
 312         if (LDST_L_BIT(instr)) {
 313                 unsigned long val;
 314                 get16t_unaligned_check(val, addr);
 315
 316                 /* signed half-word? */
 317                 if (instr & 0x40)
 318                         val = (signed long)((signed short) val);
 319
 320                 regs->uregs[rd] = val;
 321         } else
 322                 put16t_unaligned_check(regs->uregs[rd], addr);
 323
 324         return TYPE_LDST;
 325
 326  swp:
 327         printk(KERN_ERR "Alignment trap: not handling swp instruction\n");
 328  bad:
 329         return TYPE_ERROR;
 330
 331  fault:
 332         return TYPE_FAULT;
 333 }
 334
 335 static int
 336 do_alignment_ldrstr(unsigned long addr, unsigned long instr, struct pt_regs *regs)
 337 {
 338         unsigned int rd = RD_BITS(instr);
 339
 340         ai_word += 1;
 341
 342         if ((!LDST_P_BIT(instr) && LDST_W_BIT(instr)) || user_mode(regs))
 343                 goto trans;
 344
 345         if (LDST_L_BIT(instr)) {
 346                 unsigned int val;
 347                 get32_unaligned_check(val, addr);
 348                 regs->uregs[rd] = val;
 349         } else
 350                 put32_unaligned_check(regs->uregs[rd], addr);
 351         return TYPE_LDST;
 352
 353  trans:
 354         if (LDST_L_BIT(instr)) {
 355                 unsigned int val;
 356                 get32t_unaligned_check(val, addr);
 357                 regs->uregs[rd] = val;
 358         } else
 359                 put32t_unaligned_check(regs->uregs[rd], addr);
 360         return TYPE_LDST;
 361
 362  fault:
 363         return TYPE_FAULT;
 364 }
 365
 366 /*
 367  * LDM/STM alignment handler.
 368  *
 369  * There are 4 variants of this instruction:
 370  *
 371  * B = rn pointer before instruction, A = rn pointer after instruction
 372  *              ------ increasing address ----->
 373  *              |    | r0 | r1 | ... | rx |    |
 374  * PU = 01             B                    A
 375  * PU = 11        B                    A
 376  * PU = 00        A                    B
 377  * PU = 10             A                    B
 378  */
 379 static int
 380 do_alignment_ldmstm(unsigned long addr, unsigned long instr, struct pt_regs *regs)
 381 {
 382         unsigned int rd, rn, correction, nr_regs, regbits;
 383         unsigned long eaddr, newaddr;
 384
 385         if (LDM_S_BIT(instr))
 386                 goto bad;
 387
 388         correction = 4; /* processor implementation defined */
 389         regs->ARM_pc += correction;
 390
 391         ai_multi += 1;
 392
 393         /* count the number of registers in the mask to be transferred */
 394         nr_regs = hweight16(REGMASK_BITS(instr)) * 4;
 395
 396         rn = RN_BITS(instr);
 397         newaddr = eaddr = regs->uregs[rn];
 398
 399         if (!LDST_U_BIT(instr))
 400                 nr_regs = -nr_regs;
 401         newaddr += nr_regs;
 402         if (!LDST_U_BIT(instr))
 403                 eaddr = newaddr;
 404
 405         if (LDST_P_EQ_U(instr)) /* U = P */
 406                 eaddr += 4;
 407
 408         /*
 409          * For alignment faults on the ARM922T/ARM920T the MMU  makes
 410          * the FSR (and hence addr) equal to the updated base address
 411          * of the multiple access rather than the restored value.
 412          * Switch this message off if we've got a ARM92[02], otherwise
 413          * [ls]dm alignment faults are noisy!
 414          */
 415 #if !(defined CONFIG_CPU_ARM922T)  && !(defined CONFIG_CPU_ARM920T)
 416         /*
 417          * This is a "hint" - we already have eaddr worked out by the
 418          * processor for us.
 419          */
 420         if (addr != eaddr) {
 421                 printk(KERN_ERR "LDMSTM: PC = %08lx, instr = %08lx, "
 422                         "addr = %08lx, eaddr = %08lx\n",
 423                          instruction_pointer(regs), instr, addr, eaddr);
 424                 show_regs(regs);
 425         }
 426 #endif
 427
 428         if (user_mode(regs)) {
 429                 for (regbits = REGMASK_BITS(instr), rd = 0; regbits;
 430                      regbits >>= 1, rd += 1)
 431                         if (regbits & 1) {
 432                                 if (LDST_L_BIT(instr)) {
 433                                         unsigned int val;
 434                                         get32t_unaligned_check(val, eaddr);
 435                                         regs->uregs[rd] = val;
 436                                 } else
 437                                         put32t_unaligned_check(regs->uregs[rd], eaddr);
 438                                 eaddr += 4;
 439                         }
 440         } else {
 441                 for (regbits = REGMASK_BITS(instr), rd = 0; regbits;
 442                      regbits >>= 1, rd += 1)
 443                         if (regbits & 1) {
 444                                 if (LDST_L_BIT(instr)) {
 445                                         unsigned int val;
 446                                         get32_unaligned_check(val, eaddr);
 447                                         regs->uregs[rd] = val;
 448                                 } else
 449                                         put32_unaligned_check(regs->uregs[rd], eaddr);
 450                                 eaddr += 4;
 451                         }
 452         }
 453
 454         if (LDST_W_BIT(instr))
 455                 regs->uregs[rn] = newaddr;
 456         if (!LDST_L_BIT(instr) || !(REGMASK_BITS(instr) & (1 << 15)))
 457                 regs->ARM_pc -= correction;
 458         return TYPE_DONE;
 459
 460 fault:
 461         regs->ARM_pc -= correction;
 462         return TYPE_FAULT;
 463
 464 bad:
 465         printk(KERN_ERR "Alignment trap: not handling ldm with s-bit set\n");
 466         return TYPE_ERROR;
 467 }
 468
 469 /*
 470  * Convert Thumb ld/st instruction forms to equivalent ARM instructions so
 471  * we can reuse ARM userland alignment fault fixups for Thumb.
 472  *
 473  * This implementation was initially based on the algorithm found in
 474  * gdb/sim/arm/thumbemu.c. It is basically just a code reduction of same
 475  * to convert only Thumb ld/st instruction forms to equivalent ARM forms.
 476  *
 477  * NOTES:
 478  * 1. Comments below refer to ARM ARM DDI0100E Thumb Instruction sections.
 479  * 2. If for some reason we're passed an non-ld/st Thumb instruction to
 480  *    decode, we return 0xdeadc0de. This should never happen under normal
 481  *    circumstances but if it does, we've got other problems to deal with
 482  *    elsewhere and we obviously can't fix those problems here.
 483  */
 484
 485 static unsigned long
 486 thumb2arm(u16 tinstr)
 487 {
 488         u32 L = (tinstr & (1<<11)) >> 11;
 489
 490         switch ((tinstr & 0xf800) >> 11) {
 491         /* 6.5.1 Format 1: */
 492         case 0x6000 >> 11:                              /* 7.1.52 STR(1) */
 493         case 0x6800 >> 11:                              /* 7.1.26 LDR(1) */
 494         case 0x7000 >> 11:                              /* 7.1.55 STRB(1) */
 495         case 0x7800 >> 11:                              /* 7.1.30 LDRB(1) */
 496                 return 0xe5800000 |
 497                         ((tinstr & (1<<12)) << (22-12)) |       /* fixup */
 498                         (L<<20) |                               /* L==1? */
 499                         ((tinstr & (7<<0)) << (12-0)) |         /* Rd */
 500                         ((tinstr & (7<<3)) << (16-3)) |         /* Rn */
 501                         ((tinstr & (31<<6)) >>                  /* immed_5 */
 502                                 (6 - ((tinstr & (1<<12)) ? 0 : 2)));
 503         case 0x8000 >> 11:                              /* 7.1.57 STRH(1) */
 504         case 0x8800 >> 11:                              /* 7.1.32 LDRH(1) */
 505                 return 0xe1c000b0 |
 506                         (L<<20) |                               /* L==1? */
 507                         ((tinstr & (7<<0)) << (12-0)) |         /* Rd */
 508                         ((tinstr & (7<<3)) << (16-3)) |         /* Rn */
 509                         ((tinstr & (7<<6)) >> (6-1)) |   /* immed_5[2:0] */
 510                         ((tinstr & (3<<9)) >> (9-8));    /* immed_5[4:3] */
 511
 512         /* 6.5.1 Format 2: */
 513         case 0x5000 >> 11:
 514         case 0x5800 >> 11:
 515                 {
 516                         static const u32 subset[8] = {
 517                                 0xe7800000,             /* 7.1.53 STR(2) */
 518                                 0xe18000b0,             /* 7.1.58 STRH(2) */
 519                                 0xe7c00000,             /* 7.1.56 STRB(2) */
 520                                 0xe19000d0,             /* 7.1.34 LDRSB */
 521                                 0xe7900000,             /* 7.1.27 LDR(2) */
 522                                 0xe19000b0,             /* 7.1.33 LDRH(2) */
 523                                 0xe7d00000,             /* 7.1.31 LDRB(2) */
 524                                 0xe19000f0              /* 7.1.35 LDRSH */
 525                         };
 526                         return subset[(tinstr & (7<<9)) >> 9] |
 527                             ((tinstr & (7<<0)) << (12-0)) |     /* Rd */
 528                             ((tinstr & (7<<3)) << (16-3)) |     /* Rn */
 529                             ((tinstr & (7<<6)) >> (6-0));       /* Rm */
 530                 }
 531
 532         /* 6.5.1 Format 3: */
 533         case 0x4800 >> 11:                              /* 7.1.28 LDR(3) */
 534                 /* NOTE: This case is not technically possible. We're
 535                  *       loading 32-bit memory data via PC relative
 536                  *       addressing mode. So we can and should eliminate
 537                  *       this case. But I'll leave it here for now.
 538                  */
 539                 return 0xe59f0000 |
 540                     ((tinstr & (7<<8)) << (12-8)) |             /* Rd */
 541                     ((tinstr & 255) << (2-0));                  /* immed_8 */
 542
 543         /* 6.5.1 Format 4: */
 544         case 0x9000 >> 11:                              /* 7.1.54 STR(3) */
 545         case 0x9800 >> 11:                              /* 7.1.29 LDR(4) */
 546                 return 0xe58d0000 |
 547                         (L<<20) |                               /* L==1? */
 548                         ((tinstr & (7<<8)) << (12-8)) |         /* Rd */
 549                         ((tinstr & 255) << 2);                  /* immed_8 */
 550
 551         /* 6.6.1 Format 1: */
 552         case 0xc000 >> 11:                              /* 7.1.51 STMIA */
 553         case 0xc800 >> 11:                              /* 7.1.25 LDMIA */
 554                 {
 555                         u32 Rn = (tinstr & (7<<8)) >> 8;
 556                         u32 W = ((L<<Rn) & (tinstr&255)) ? 0 : 1<<21;
 557
 558                         return 0xe8800000 | W | (L<<20) | (Rn<<16) |
 559                                 (tinstr&255);
 560                 }
 561
 562         /* 6.6.1 Format 2: */
 563         case 0xb000 >> 11:                              /* 7.1.48 PUSH */
 564         case 0xb800 >> 11:                              /* 7.1.47 POP */
 565                 if ((tinstr & (3 << 9)) == 0x0400) {
 566                         static const u32 subset[4] = {
 567                                 0xe92d0000,     /* STMDB sp!,{registers} */
 568                                 0xe92d4000,     /* STMDB sp!,{registers,lr} */
 569                                 0xe8bd0000,     /* LDMIA sp!,{registers} */
 570                                 0xe8bd8000      /* LDMIA sp!,{registers,pc} */
 571                         };
 572                         return subset[(L<<1) | ((tinstr & (1<<8)) >> 8)] |
 573                             (tinstr & 255);             /* register_list */
 574                 }
 575                 /* Else fall through for illegal instruction case */
 576
 577         default:
 578                 return 0xdeadc0de;
 579         }
 580 }
 581
 582 static int
 583 do_alignment(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
 584 {
 585         union offset_union offset;
 586         unsigned long instr = 0, instrptr;
 587         int (*handler)(unsigned long addr, unsigned long instr, struct pt_regs *regs);
 588         unsigned int type;
 589         mm_segment_t fs;
 590         unsigned int fault;
 591         u16 tinstr = 0;
 592
 593         instrptr = instruction_pointer(regs);
 594
 595         fs = get_fs();
 596         set_fs(KERNEL_DS);
 597         if thumb_mode(regs) {
 598                 fault = __get_user(tinstr, (u16 *)(instrptr & ~1));
 599                 if (!(fault))
 600                         instr = thumb2arm(tinstr);
 601         } else
 602                 fault = __get_user(instr, (u32 *)instrptr);
 603         set_fs(fs);
 604
 605         if (fault) {
 606                 type = TYPE_FAULT;
 607                 goto bad_or_fault;
 608         }
 609
 610         if (user_mode(regs))
 611                 goto user;
 612
 613         ai_sys += 1;
 614
 615  fixup:
 616
 617         regs->ARM_pc += thumb_mode(regs) ? 2 : 4;
 618
 619         switch (CODING_BITS(instr)) {
 620         case 0x00000000:        /* ldrh or strh */
 621                 if (LDSTH_I_BIT(instr))
 622                         offset.un = (instr & 0xf00) >> 4 | (instr & 15);
 623                 else
 624                         offset.un = regs->uregs[RM_BITS(instr)];
 625                 handler = do_alignment_ldrhstrh;
 626                 break;
 627
 628         case 0x04000000:        /* ldr or str immediate */
 629                 offset.un = OFFSET_BITS(instr);
 630                 handler = do_alignment_ldrstr;
 631                 break;
 632
 633         case 0x06000000:        /* ldr or str register */
 634                 offset.un = regs->uregs[RM_BITS(instr)];
 635
 636                 if (IS_SHIFT(instr)) {
 637                         unsigned int shiftval = SHIFT_BITS(instr);
 638
 639                         switch(SHIFT_TYPE(instr)) {
 640                         case SHIFT_LSL:
 641                                 offset.un <<= shiftval;
 642                                 break;
 643
 644                         case SHIFT_LSR:
 645                                 offset.un >>= shiftval;
 646                                 break;
 647
 648                         case SHIFT_ASR:
 649                                 offset.sn >>= shiftval;
 650                                 break;
 651
 652                         case SHIFT_RORRRX:
 653                                 if (shiftval == 0) {
 654                                         offset.un >>= 1;
 655                                         if (regs->ARM_cpsr & PSR_C_BIT)
 656                                                 offset.un |= 1 << 31;
 657                                 } else
 658                                         offset.un = offset.un >> shiftval |
 659                                                           offset.un << (32 - shiftval);
 660                                 break;
 661                         }
 662                 }
 663                 handler = do_alignment_ldrstr;
 664                 break;
 665
 666         case 0x08000000:        /* ldm or stm */
 667                 handler = do_alignment_ldmstm;
 668                 break;
 669
 670         default:
 671                 goto bad;
 672         }
 673
 674         type = handler(addr, instr, regs);
 675
 676         if (type == TYPE_ERROR || type == TYPE_FAULT)
 677                 goto bad_or_fault;
 678
 679         if (type == TYPE_LDST)
 680                 do_alignment_finish_ldst(addr, instr, regs, offset);
 681
 682         return 0;
 683
 684  bad_or_fault:
 685         if (type == TYPE_ERROR)
 686                 goto bad;
 687         regs->ARM_pc -= thumb_mode(regs) ? 2 : 4;
 688         /*
 689          * We got a fault - fix it up, or die.
 690          */
 691         do_bad_area(current, current->mm, addr, fsr, regs);
 692         return 0;
 693
 694  bad:
 695         /*
 696          * Oops, we didn't handle the instruction.
 697          */
 698         printk(KERN_ERR "Alignment trap: not handling instruction "
 699                 "%0*lx at [<%08lx>]\n",
 700                 thumb_mode(regs) ? 4 : 8,
 701                 thumb_mode(regs) ? tinstr : instr, instrptr);
 702         ai_skipped += 1;
 703         return 1;
 704
 705  user:
 706         ai_user += 1;
 707
 708         if (ai_usermode & 1)
 709                 printk("Alignment trap: %s (%d) PC=0x%08lx Instr=0x%0*lx "
 710                        "Address=0x%08lx FSR 0x%03x\n", current->comm,
 711                         current->pid, instrptr,
 712                         thumb_mode(regs) ? 4 : 8,
 713                         thumb_mode(regs) ? tinstr : instr,
 714                         addr, fsr);
 715
 716         if (ai_usermode & 2)
 717                 goto fixup;
 718
 719         if (ai_usermode & 4)
 720                 force_sig(SIGBUS, current);
 721         else
 722                 set_cr(cr_no_alignment);
 723
 724         return 0;
 725 }
 726
 727 /*
 728  * This needs to be done after sysctl_init, otherwise sys/ will be
 729  * overwritten.  Actually, this shouldn't be in sys/ at all since
 730  * it isn't a sysctl, and it doesn't contain sysctl information.
 731  * We now locate it in /proc/cpu/alignment instead.
 732  */
 733 static int __init alignment_init(void)
 734 {
 735 #ifdef CONFIG_PROC_FS
 736         struct proc_dir_entry *res;
 737
 738         res = proc_mkdir("cpu", NULL);
 739         if (!res)
 740                 return -ENOMEM;
 741
 742         res = create_proc_entry("alignment", S_IWUSR | S_IRUGO, res);
 743         if (!res)
 744                 return -ENOMEM;
 745
 746         res->read_proc = proc_alignment_read;
 747         res->write_proc = proc_alignment_write;
 748 #endif
 749
 750         hook_fault_code(1, do_alignment, SIGILL, "alignment exception");
 751         hook_fault_code(3, do_alignment, SIGILL, "alignment exception");
 752
 753         return 0;
 754 }
 755
 756 fs_initcall(alignment_init);