arch/arm/mm/alignment.c

   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/compiler.h>
  15 #include <linux/kernel.h>
  16 #include <linux/errno.h>
  17 #include <linux/string.h>
  18 #include <linux/proc_fs.h>
  19 #include <linux/init.h>
  20
  21 #include <asm/uaccess.h>
  22 #include <asm/unaligned.h>
  23
  24 #include "fault.h"
  25
  26 /*
  27  * 32-bit misaligned trap handler (c) 1998 San Mehat (CCC) -July 1998
  28  * /proc/sys/debug/alignment, modified and integrated into
  29  * Linux 2.1 by Russell King
  30  *
  31  * Speed optimisations and better fault handling by Russell King.
  32  *
  33  * *** NOTE ***
  34  * This code is not portable to processors with late data abort handling.
  35  */
  36 #define CODING_BITS(i)  (i & 0x0e000000)
  37
  38 #define LDST_I_BIT(i)   (i & (1 << 26))         /* Immediate constant   */
  39 #define LDST_P_BIT(i)   (i & (1 << 24))         /* Preindex             */
  40 #define LDST_U_BIT(i)   (i & (1 << 23))         /* Add offset           */
  41 #define LDST_W_BIT(i)   (i & (1 << 21))         /* Writeback            */
  42 #define LDST_L_BIT(i)   (i & (1 << 20))         /* Load                 */
  43
  44 #define LDST_P_EQ_U(i)  ((((i) ^ ((i) >> 1)) & (1 << 23)) == 0)
  45
  46 #define LDSTHD_I_BIT(i) (i & (1 << 22))         /* double/half-word immed */
  47 #define LDM_S_BIT(i)    (i & (1 << 22))         /* write CPSR from SPSR */
  48
  49 #define RN_BITS(i)      ((i >> 16) & 15)        /* Rn                   */
  50 #define RD_BITS(i)      ((i >> 12) & 15)        /* Rd                   */
  51 #define RM_BITS(i)      (i & 15)                /* Rm                   */
  52
  53 #define REGMASK_BITS(i) (i & 0xffff)
  54 #define OFFSET_BITS(i)  (i & 0x0fff)
  55
  56 #define IS_SHIFT(i)     (i & 0x0ff0)
  57 #define SHIFT_BITS(i)   ((i >> 7) & 0x1f)
  58 #define SHIFT_TYPE(i)   (i & 0x60)
  59 #define SHIFT_LSL       0x00
  60 #define SHIFT_LSR       0x20
  61 #define SHIFT_ASR       0x40
  62 #define SHIFT_RORRRX    0x60
  63
  64 static unsigned long ai_user;
  65 static unsigned long ai_sys;
  66 static unsigned long ai_skipped;
  67 static unsigned long ai_half;
  68 static unsigned long ai_word;
  69 static unsigned long ai_dword;
  70 static unsigned long ai_multi;
  71 static int ai_usermode;
  72
  73 #ifdef CONFIG_PROC_FS
  74 static const char *usermode_action[] = {
  75         "ignored",
  76         "warn",
  77         "fixup",
  78         "fixup+warn",
  79         "signal",
  80         "signal+warn"
  81 };
  82
  83 static int
  84 proc_alignment_read(char *page, char **start, off_t off, int count, int *eof,
  85                     void *data)
  86 {
  87         char *p = page;
  88         int len;
  89
  90         p += sprintf(p, "User:\t\t%lu\n", ai_user);
  91         p += sprintf(p, "System:\t\t%lu\n", ai_sys);
  92         p += sprintf(p, "Skipped:\t%lu\n", ai_skipped);
  93         p += sprintf(p, "Half:\t\t%lu\n", ai_half);
  94         p += sprintf(p, "Word:\t\t%lu\n", ai_word);
  95         if (cpu_architecture() >= CPU_ARCH_ARMv5TE)
  96                 p += sprintf(p, "DWord:\t\t%lu\n", ai_dword);
  97         p += sprintf(p, "Multi:\t\t%lu\n", ai_multi);
  98         p += sprintf(p, "User faults:\t%i (%s)\n", ai_usermode,
  99                         usermode_action[ai_usermode]);
 100
 101         len = (p - page) - off;
 102         if (len < 0)
 103                 len = 0;
 104
 105         *eof = (len <= count) ? 1 : 0;
 106         *start = page + off;
 107
 108         return len;
 109 }
 110
 111 static int proc_alignment_write(struct file *file, const char __user *buffer,
 112                                 unsigned long count, void *data)
 113 {
 114         char mode;
 115
 116         if (count > 0) {
 117                 if (get_user(mode, buffer))
 118                         return -EFAULT;
 119                 if (mode >= '0' && mode <= '5')
 120                         ai_usermode = mode - '0';
 121         }
 122         return count;
 123 }
 124
 125 #endif /* CONFIG_PROC_FS */
 126
 127 union offset_union {
 128         unsigned long un;
 129           signed long sn;
 130 };
 131
 132 #define TYPE_ERROR      0
 133 #define TYPE_FAULT      1
 134 #define TYPE_LDST       2
 135 #define TYPE_DONE       3
 136
 137 #ifdef __ARMEB__
 138 #define BE              1
 139 #define FIRST_BYTE_16   "mov    %1, %1, ror #8\n"
 140 #define FIRST_BYTE_32   "mov    %1, %1, ror #24\n"
 141 #define NEXT_BYTE       "ror #24"
 142 #else
 143 #define BE              0
 144 #define FIRST_BYTE_16
 145 #define FIRST_BYTE_32
 146 #define NEXT_BYTE       "lsr #8"
 147 #endif
 148
 149 #define __get8_unaligned_check(ins,val,addr,err)        \
 150         __asm__(                                        \
 151         "1:     "ins"   %1, [%2], #1\n"                 \
 152         "2:\n"                                          \
 153         "       .section .fixup,\"ax\"\n"               \
 154         "       .align  2\n"                            \
 155         "3:     mov     %0, #1\n"                       \
 156         "       b       2b\n"                           \
 157         "       .previous\n"                            \
 158         "       .section __ex_table,\"a\"\n"            \
 159         "       .align  3\n"                            \
 160         "       .long   1b, 3b\n"                       \
 161         "       .previous\n"                            \
 162         : "=r" (err), "=&r" (val), "=r" (addr)          \
 163         : "0" (err), "2" (addr))
 164
 165 #define __get16_unaligned_check(ins,val,addr)                   \
 166         do {                                                    \
 167                 unsigned int err = 0, v, a = addr;              \
 168                 __get8_unaligned_check(ins,v,a,err);            \
 169                 val =  v << ((BE) ? 8 : 0);                     \
 170                 __get8_unaligned_check(ins,v,a,err);            \
 171                 val |= v << ((BE) ? 0 : 8);                     \
 172                 if (err)                                        \
 173                         goto fault;                             \
 174         } while (0)
 175
 176 #define get16_unaligned_check(val,addr) \
 177         __get16_unaligned_check("ldrb",val,addr)
 178
 179 #define get16t_unaligned_check(val,addr) \
 180         __get16_unaligned_check("ldrbt",val,addr)
 181
 182 #define __get32_unaligned_check(ins,val,addr)                   \
 183         do {                                                    \
 184                 unsigned int err = 0, v, a = addr;              \
 185                 __get8_unaligned_check(ins,v,a,err);            \
 186                 val =  v << ((BE) ? 24 :  0);                   \
 187                 __get8_unaligned_check(ins,v,a,err);            \
 188                 val |= v << ((BE) ? 16 :  8);                   \
 189                 __get8_unaligned_check(ins,v,a,err);            \
 190                 val |= v << ((BE) ?  8 : 16);                   \
 191                 __get8_unaligned_check(ins,v,a,err);            \
 192                 val |= v << ((BE) ?  0 : 24);                   \
 193                 if (err)                                        \
 194                         goto fault;                             \
 195         } while (0)
 196
 197 #define get32_unaligned_check(val,addr) \
 198         __get32_unaligned_check("ldrb",val,addr)
 199
 200 #define get32t_unaligned_check(val,addr) \
 201         __get32_unaligned_check("ldrbt",val,addr)
 202
 203 #define __put16_unaligned_check(ins,val,addr)                   \
 204         do {                                                    \
 205                 unsigned int err = 0, v = val, a = addr;        \
 206                 __asm__( FIRST_BYTE_16                          \
 207                 "1:     "ins"   %1, [%2], #1\n"                 \
 208                 "       mov     %1, %1, "NEXT_BYTE"\n"          \
 209                 "2:     "ins"   %1, [%2]\n"                     \
 210                 "3:\n"                                          \
 211                 "       .section .fixup,\"ax\"\n"               \
 212                 "       .align  2\n"                            \
 213                 "4:     mov     %0, #1\n"                       \
 214                 "       b       3b\n"                           \
 215                 "       .previous\n"                            \
 216                 "       .section __ex_table,\"a\"\n"            \
 217                 "       .align  3\n"                            \
 218                 "       .long   1b, 4b\n"                       \
 219                 "       .long   2b, 4b\n"                       \
 220                 "       .previous\n"                            \
 221                 : "=r" (err), "=&r" (v), "=&r" (a)              \
 222                 : "0" (err), "1" (v), "2" (a));                 \
 223                 if (err)                                        \
 224                         goto fault;                             \
 225         } while (0)
 226
 227 #define put16_unaligned_check(val,addr)  \
 228         __put16_unaligned_check("strb",val,addr)
 229
 230 #define put16t_unaligned_check(val,addr) \
 231         __put16_unaligned_check("strbt",val,addr)
 232
 233 #define __put32_unaligned_check(ins,val,addr)                   \
 234         do {                                                    \
 235                 unsigned int err = 0, v = val, a = addr;        \
 236                 __asm__( FIRST_BYTE_32                          \
 237                 "1:     "ins"   %1, [%2], #1\n"                 \
 238                 "       mov     %1, %1, "NEXT_BYTE"\n"          \
 239                 "2:     "ins"   %1, [%2], #1\n"                 \
 240                 "       mov     %1, %1, "NEXT_BYTE"\n"          \
 241                 "3:     "ins"   %1, [%2], #1\n"                 \
 242                 "       mov     %1, %1, "NEXT_BYTE"\n"          \
 243                 "4:     "ins"   %1, [%2]\n"                     \
 244                 "5:\n"                                          \
 245                 "       .section .fixup,\"ax\"\n"               \
 246                 "       .align  2\n"                            \
 247                 "6:     mov     %0, #1\n"                       \
 248                 "       b       5b\n"                           \
 249                 "       .previous\n"                            \
 250                 "       .section __ex_table,\"a\"\n"            \
 251                 "       .align  3\n"                            \
 252                 "       .long   1b, 6b\n"                       \
 253                 "       .long   2b, 6b\n"                       \
 254                 "       .long   3b, 6b\n"                       \
 255                 "       .long   4b, 6b\n"                       \
 256                 "       .previous\n"                            \
 257                 : "=r" (err), "=&r" (v), "=&r" (a)              \
 258                 : "0" (err), "1" (v), "2" (a));                 \
 259                 if (err)                                        \
 260                         goto fault;                             \
 261         } while (0)
 262
 263 #define put32_unaligned_check(val,addr) \
 264         __put32_unaligned_check("strb", val, addr)
 265
 266 #define put32t_unaligned_check(val,addr) \
 267         __put32_unaligned_check("strbt", val, addr)
 268
 269 static void
 270 do_alignment_finish_ldst(unsigned long addr, unsigned long instr, struct pt_regs *regs, union offset_union offset)
 271 {
 272         if (!LDST_U_BIT(instr))
 273                 offset.un = -offset.un;
 274
 275         if (!LDST_P_BIT(instr))
 276                 addr += offset.un;
 277
 278         if (!LDST_P_BIT(instr) || LDST_W_BIT(instr))
 279                 regs->uregs[RN_BITS(instr)] = addr;
 280 }
 281
 282 static int
 283 do_alignment_ldrhstrh(unsigned long addr, unsigned long instr, struct pt_regs *regs)
 284 {
 285         unsigned int rd = RD_BITS(instr);
 286
 287         ai_half += 1;
 288
 289         if (user_mode(regs))
 290                 goto user;
 291
 292         if (LDST_L_BIT(instr)) {
 293                 unsigned long val;
 294                 get16_unaligned_check(val, addr);
 295
 296                 /* signed half-word? */
 297                 if (instr & 0x40)
 298                         val = (signed long)((signed short) val);
 299
 300                 regs->uregs[rd] = val;
 301         } else
 302                 put16_unaligned_check(regs->uregs[rd], addr);
 303
 304         return TYPE_LDST;
 305
 306  user:
 307         if (LDST_L_BIT(instr)) {
 308                 unsigned long val;
 309                 get16t_unaligned_check(val, addr);
 310
 311                 /* signed half-word? */
 312                 if (instr & 0x40)
 313                         val = (signed long)((signed short) val);
 314
 315                 regs->uregs[rd] = val;
 316         } else
 317                 put16t_unaligned_check(regs->uregs[rd], addr);
 318
 319         return TYPE_LDST;
 320
 321  fault:
 322         return TYPE_FAULT;
 323 }
 324
 325 static int
 326 do_alignment_ldrdstrd(unsigned long addr, unsigned long instr,
 327                       struct pt_regs *regs)
 328 {
 329         unsigned int rd = RD_BITS(instr);
 330
 331         if (((rd & 1) == 1) || (rd == 14))
 332                 goto bad;
 333
 334         ai_dword += 1;
 335
 336         if (user_mode(regs))
 337                 goto user;
 338
 339         if ((instr & 0xf0) == 0xd0) {
 340                 unsigned long val;
 341                 get32_unaligned_check(val, addr);
 342                 regs->uregs[rd] = val;
 343                 get32_unaligned_check(val, addr + 4);
 344                 regs->uregs[rd + 1] = val;
 345         } else {
 346                 put32_unaligned_check(regs->uregs[rd], addr);
 347                 put32_unaligned_check(regs->uregs[rd + 1], addr + 4);
 348         }
 349
 350         return TYPE_LDST;
 351
 352  user:
 353         if ((instr & 0xf0) == 0xd0) {
 354                 unsigned long val;
 355                 get32t_unaligned_check(val, addr);
 356                 regs->uregs[rd] = val;
 357                 get32t_unaligned_check(val, addr + 4);
 358                 regs->uregs[rd + 1] = val;
 359         } else {
 360                 put32t_unaligned_check(regs->uregs[rd], addr);
 361                 put32t_unaligned_check(regs->uregs[rd + 1], addr + 4);
 362         }
 363
 364         return TYPE_LDST;
 365  bad:
 366         return TYPE_ERROR;
 367  fault:
 368         return TYPE_FAULT;
 369 }
 370
 371 static int
 372 do_alignment_ldrstr(unsigned long addr, unsigned long instr, struct pt_regs *regs)
 373 {
 374         unsigned int rd = RD_BITS(instr);
 375
 376         ai_word += 1;
 377
 378         if ((!LDST_P_BIT(instr) && LDST_W_BIT(instr)) || user_mode(regs))
 379                 goto trans;
 380
 381         if (LDST_L_BIT(instr)) {
 382                 unsigned int val;
 383                 get32_unaligned_check(val, addr);
 384                 regs->uregs[rd] = val;
 385         } else
 386                 put32_unaligned_check(regs->uregs[rd], addr);
 387         return TYPE_LDST;
 388
 389  trans:
 390         if (LDST_L_BIT(instr)) {
 391                 unsigned int val;
 392                 get32t_unaligned_check(val, addr);
 393                 regs->uregs[rd] = val;
 394         } else
 395                 put32t_unaligned_check(regs->uregs[rd], addr);
 396         return TYPE_LDST;
 397
 398  fault:
 399         return TYPE_FAULT;
 400 }
 401
 402 /*
 403  * LDM/STM alignment handler.
 404  *
 405  * There are 4 variants of this instruction:
 406  *
 407  * B = rn pointer before instruction, A = rn pointer after instruction
 408  *              ------ increasing address ----->
 409  *              |    | r0 | r1 | ... | rx |    |
 410  * PU = 01             B                    A
 411  * PU = 11        B                    A
 412  * PU = 00        A                    B
 413  * PU = 10             A                    B
 414  */
 415 static int
 416 do_alignment_ldmstm(unsigned long addr, unsigned long instr, struct pt_regs *regs)
 417 {
 418         unsigned int rd, rn, correction, nr_regs, regbits;
 419         unsigned long eaddr, newaddr;
 420
 421         if (LDM_S_BIT(instr))
 422                 goto bad;
 423
 424         correction = 4; /* processor implementation defined */
 425         regs->ARM_pc += correction;
 426
 427         ai_multi += 1;
 428
 429         /* count the number of registers in the mask to be transferred */
 430         nr_regs = hweight16(REGMASK_BITS(instr)) * 4;
 431
 432         rn = RN_BITS(instr);
 433         newaddr = eaddr = regs->uregs[rn];
 434
 435         if (!LDST_U_BIT(instr))
 436                 nr_regs = -nr_regs;
 437         newaddr += nr_regs;
 438         if (!LDST_U_BIT(instr))
 439                 eaddr = newaddr;
 440
 441         if (LDST_P_EQ_U(instr)) /* U = P */
 442                 eaddr += 4;
 443
 444         /*
 445          * For alignment faults on the ARM922T/ARM920T the MMU  makes
 446          * the FSR (and hence addr) equal to the updated base address
 447          * of the multiple access rather than the restored value.
 448          * Switch this message off if we've got a ARM92[02], otherwise
 449          * [ls]dm alignment faults are noisy!
 450          */
 451 #if !(defined CONFIG_CPU_ARM922T)  && !(defined CONFIG_CPU_ARM920T)
 452         /*
 453          * This is a "hint" - we already have eaddr worked out by the
 454          * processor for us.
 455          */
 456         if (addr != eaddr) {
 457                 printk(KERN_ERR "LDMSTM: PC = %08lx, instr = %08lx, "
 458                         "addr = %08lx, eaddr = %08lx\n",
 459                          instruction_pointer(regs), instr, addr, eaddr);
 460                 show_regs(regs);
 461         }
 462 #endif
 463
 464         if (user_mode(regs)) {
 465                 for (regbits = REGMASK_BITS(instr), rd = 0; regbits;
 466                      regbits >>= 1, rd += 1)
 467                         if (regbits & 1) {
 468                                 if (LDST_L_BIT(instr)) {
 469                                         unsigned int val;
 470                                         get32t_unaligned_check(val, eaddr);
 471                                         regs->uregs[rd] = val;
 472                                 } else
 473                                         put32t_unaligned_check(regs->uregs[rd], eaddr);
 474                                 eaddr += 4;
 475                         }
 476         } else {
 477                 for (regbits = REGMASK_BITS(instr), rd = 0; regbits;
 478                      regbits >>= 1, rd += 1)
 479                         if (regbits & 1) {
 480                                 if (LDST_L_BIT(instr)) {
 481                                         unsigned int val;
 482                                         get32_unaligned_check(val, eaddr);
 483                                         regs->uregs[rd] = val;
 484                                 } else
 485                                         put32_unaligned_check(regs->uregs[rd], eaddr);
 486                                 eaddr += 4;
 487                         }
 488         }
 489
 490         if (LDST_W_BIT(instr))
 491                 regs->uregs[rn] = newaddr;
 492         if (!LDST_L_BIT(instr) || !(REGMASK_BITS(instr) & (1 << 15)))
 493                 regs->ARM_pc -= correction;
 494         return TYPE_DONE;
 495
 496 fault:
 497         regs->ARM_pc -= correction;
 498         return TYPE_FAULT;
 499
 500 bad:
 501         printk(KERN_ERR "Alignment trap: not handling ldm with s-bit set\n");
 502         return TYPE_ERROR;
 503 }
 504
 505 /*
 506  * Convert Thumb ld/st instruction forms to equivalent ARM instructions so
 507  * we can reuse ARM userland alignment fault fixups for Thumb.
 508  *
 509  * This implementation was initially based on the algorithm found in
 510  * gdb/sim/arm/thumbemu.c. It is basically just a code reduction of same
 511  * to convert only Thumb ld/st instruction forms to equivalent ARM forms.
 512  *
 513  * NOTES:
 514  * 1. Comments below refer to ARM ARM DDI0100E Thumb Instruction sections.
 515  * 2. If for some reason we're passed an non-ld/st Thumb instruction to
 516  *    decode, we return 0xdeadc0de. This should never happen under normal
 517  *    circumstances but if it does, we've got other problems to deal with
 518  *    elsewhere and we obviously can't fix those problems here.
 519  */
 520
 521 static unsigned long
 522 thumb2arm(u16 tinstr)
 523 {
 524         u32 L = (tinstr & (1<<11)) >> 11;
 525
 526         switch ((tinstr & 0xf800) >> 11) {
 527         /* 6.5.1 Format 1: */
 528         case 0x6000 >> 11:                              /* 7.1.52 STR(1) */
 529         case 0x6800 >> 11:                              /* 7.1.26 LDR(1) */
 530         case 0x7000 >> 11:                              /* 7.1.55 STRB(1) */
 531         case 0x7800 >> 11:                              /* 7.1.30 LDRB(1) */
 532                 return 0xe5800000 |
 533                         ((tinstr & (1<<12)) << (22-12)) |       /* fixup */
 534                         (L<<20) |                               /* L==1? */
 535                         ((tinstr & (7<<0)) << (12-0)) |         /* Rd */
 536                         ((tinstr & (7<<3)) << (16-3)) |         /* Rn */
 537                         ((tinstr & (31<<6)) >>                  /* immed_5 */
 538                                 (6 - ((tinstr & (1<<12)) ? 0 : 2)));
 539         case 0x8000 >> 11:                              /* 7.1.57 STRH(1) */
 540         case 0x8800 >> 11:                              /* 7.1.32 LDRH(1) */
 541                 return 0xe1c000b0 |
 542                         (L<<20) |                               /* L==1? */
 543                         ((tinstr & (7<<0)) << (12-0)) |         /* Rd */
 544                         ((tinstr & (7<<3)) << (16-3)) |         /* Rn */
 545                         ((tinstr & (7<<6)) >> (6-1)) |   /* immed_5[2:0] */
 546                         ((tinstr & (3<<9)) >> (9-8));    /* immed_5[4:3] */
 547
 548         /* 6.5.1 Format 2: */
 549         case 0x5000 >> 11:
 550         case 0x5800 >> 11:
 551                 {
 552                         static const u32 subset[8] = {
 553                                 0xe7800000,             /* 7.1.53 STR(2) */
 554                                 0xe18000b0,             /* 7.1.58 STRH(2) */
 555                                 0xe7c00000,             /* 7.1.56 STRB(2) */
 556                                 0xe19000d0,             /* 7.1.34 LDRSB */
 557                                 0xe7900000,             /* 7.1.27 LDR(2) */
 558                                 0xe19000b0,             /* 7.1.33 LDRH(2) */
 559                                 0xe7d00000,             /* 7.1.31 LDRB(2) */
 560                                 0xe19000f0              /* 7.1.35 LDRSH */
 561                         };
 562                         return subset[(tinstr & (7<<9)) >> 9] |
 563                             ((tinstr & (7<<0)) << (12-0)) |     /* Rd */
 564                             ((tinstr & (7<<3)) << (16-3)) |     /* Rn */
 565                             ((tinstr & (7<<6)) >> (6-0));       /* Rm */
 566                 }
 567
 568         /* 6.5.1 Format 3: */
 569         case 0x4800 >> 11:                              /* 7.1.28 LDR(3) */
 570                 /* NOTE: This case is not technically possible. We're
 571                  *       loading 32-bit memory data via PC relative
 572                  *       addressing mode. So we can and should eliminate
 573                  *       this case. But I'll leave it here for now.
 574                  */
 575                 return 0xe59f0000 |
 576                     ((tinstr & (7<<8)) << (12-8)) |             /* Rd */
 577                     ((tinstr & 255) << (2-0));                  /* immed_8 */
 578
 579         /* 6.5.1 Format 4: */
 580         case 0x9000 >> 11:                              /* 7.1.54 STR(3) */
 581         case 0x9800 >> 11:                              /* 7.1.29 LDR(4) */
 582                 return 0xe58d0000 |
 583                         (L<<20) |                               /* L==1? */
 584                         ((tinstr & (7<<8)) << (12-8)) |         /* Rd */
 585                         ((tinstr & 255) << 2);                  /* immed_8 */
 586
 587         /* 6.6.1 Format 1: */
 588         case 0xc000 >> 11:                              /* 7.1.51 STMIA */
 589         case 0xc800 >> 11:                              /* 7.1.25 LDMIA */
 590                 {
 591                         u32 Rn = (tinstr & (7<<8)) >> 8;
 592                         u32 W = ((L<<Rn) & (tinstr&255)) ? 0 : 1<<21;
 593
 594                         return 0xe8800000 | W | (L<<20) | (Rn<<16) |
 595                                 (tinstr&255);
 596                 }
 597
 598         /* 6.6.1 Format 2: */
 599         case 0xb000 >> 11:                              /* 7.1.48 PUSH */
 600         case 0xb800 >> 11:                              /* 7.1.47 POP */
 601                 if ((tinstr & (3 << 9)) == 0x0400) {
 602                         static const u32 subset[4] = {
 603                                 0xe92d0000,     /* STMDB sp!,{registers} */
 604                                 0xe92d4000,     /* STMDB sp!,{registers,lr} */
 605                                 0xe8bd0000,     /* LDMIA sp!,{registers} */
 606                                 0xe8bd8000      /* LDMIA sp!,{registers,pc} */
 607                         };
 608                         return subset[(L<<1) | ((tinstr & (1<<8)) >> 8)] |
 609                             (tinstr & 255);             /* register_list */
 610                 }
 611                 /* Else fall through for illegal instruction case */
 612
 613         default:
 614                 return 0xdeadc0de;
 615         }
 616 }
 617
 618 static int
 619 do_alignment(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
 620 {
 621         union offset_union offset;
 622         unsigned long instr = 0, instrptr;
 623         int (*handler)(unsigned long addr, unsigned long instr, struct pt_regs *regs);
 624         unsigned int type;
 625         mm_segment_t fs;
 626         unsigned int fault;
 627         u16 tinstr = 0;
 628
 629         instrptr = instruction_pointer(regs);
 630
 631         fs = get_fs();
 632         set_fs(KERNEL_DS);
 633         if thumb_mode(regs) {
 634                 fault = __get_user(tinstr, (u16 *)(instrptr & ~1));
 635                 if (!(fault))
 636                         instr = thumb2arm(tinstr);
 637         } else
 638                 fault = __get_user(instr, (u32 *)instrptr);
 639         set_fs(fs);
 640
 641         if (fault) {
 642                 type = TYPE_FAULT;
 643                 goto bad_or_fault;
 644         }
 645
 646         if (user_mode(regs))
 647                 goto user;
 648
 649         ai_sys += 1;
 650
 651  fixup:
 652
 653         regs->ARM_pc += thumb_mode(regs) ? 2 : 4;
 654
 655         switch (CODING_BITS(instr)) {
 656         case 0x00000000:        /* 3.13.4 load/store instruction extensions */
 657                 if (LDSTHD_I_BIT(instr))
 658                         offset.un = (instr & 0xf00) >> 4 | (instr & 15);
 659                 else
 660                         offset.un = regs->uregs[RM_BITS(instr)];
 661
 662                 if ((instr & 0x000000f0) == 0x000000b0 || /* LDRH, STRH */
 663                     (instr & 0x001000f0) == 0x001000f0)   /* LDRSH */
 664                         handler = do_alignment_ldrhstrh;
 665                 else if ((instr & 0x001000f0) == 0x000000d0 || /* LDRD */
 666                          (instr & 0x001000f0) == 0x000000f0)   /* STRD */
 667                         handler = do_alignment_ldrdstrd;
 668                 else if ((instr & 0x01f00ff0) == 0x01000090) /* SWP */
 669                         goto swp;
 670                 else
 671                         goto bad;
 672                 break;
 673
 674         case 0x04000000:        /* ldr or str immediate */
 675                 offset.un = OFFSET_BITS(instr);
 676                 handler = do_alignment_ldrstr;
 677                 break;
 678
 679         case 0x06000000:        /* ldr or str register */
 680                 offset.un = regs->uregs[RM_BITS(instr)];
 681
 682                 if (IS_SHIFT(instr)) {
 683                         unsigned int shiftval = SHIFT_BITS(instr);
 684
 685                         switch(SHIFT_TYPE(instr)) {
 686                         case SHIFT_LSL:
 687                                 offset.un <<= shiftval;
 688                                 break;
 689
 690                         case SHIFT_LSR:
 691                                 offset.un >>= shiftval;
 692                                 break;
 693
 694                         case SHIFT_ASR:
 695                                 offset.sn >>= shiftval;
 696                                 break;
 697
 698                         case SHIFT_RORRRX:
 699                                 if (shiftval == 0) {
 700                                         offset.un >>= 1;
 701                                         if (regs->ARM_cpsr & PSR_C_BIT)
 702                                                 offset.un |= 1 << 31;
 703                                 } else
 704                                         offset.un = offset.un >> shiftval |
 705                                                           offset.un << (32 - shiftval);
 706                                 break;
 707                         }
 708                 }
 709                 handler = do_alignment_ldrstr;
 710                 break;
 711
 712         case 0x08000000:        /* ldm or stm */
 713                 handler = do_alignment_ldmstm;
 714                 break;
 715
 716         default:
 717                 goto bad;
 718         }
 719
 720         type = handler(addr, instr, regs);
 721
 722         if (type == TYPE_ERROR || type == TYPE_FAULT)
 723                 goto bad_or_fault;
 724
 725         if (type == TYPE_LDST)
 726                 do_alignment_finish_ldst(addr, instr, regs, offset);
 727
 728         return 0;
 729
 730  bad_or_fault:
 731         if (type == TYPE_ERROR)
 732                 goto bad;
 733         regs->ARM_pc -= thumb_mode(regs) ? 2 : 4;
 734         /*
 735          * We got a fault - fix it up, or die.
 736          */
 737         do_bad_area(addr, fsr, regs);
 738         return 0;
 739
 740  swp:
 741         printk(KERN_ERR "Alignment trap: not handling swp instruction\n");
 742
 743  bad:
 744         /*
 745          * Oops, we didn't handle the instruction.
 746          */
 747         printk(KERN_ERR "Alignment trap: not handling instruction "
 748                 "%0*lx at [<%08lx>]\n",
 749                 thumb_mode(regs) ? 4 : 8,
 750                 thumb_mode(regs) ? tinstr : instr, instrptr);
 751         ai_skipped += 1;
 752         return 1;
 753
 754  user:
 755         ai_user += 1;
 756
 757         if (ai_usermode & 1)
 758                 printk("Alignment trap: %s (%d) PC=0x%08lx Instr=0x%0*lx "
 759                        "Address=0x%08lx FSR 0x%03x\n", current->comm,
 760                         current->pid, instrptr,
 761                         thumb_mode(regs) ? 4 : 8,
 762                         thumb_mode(regs) ? tinstr : instr,
 763                         addr, fsr);
 764
 765         if (ai_usermode & 2)
 766                 goto fixup;
 767
 768         if (ai_usermode & 4)
 769                 force_sig(SIGBUS, current);
 770         else
 771                 set_cr(cr_no_alignment);
 772
 773         return 0;
 774 }
 775
 776 /*
 777  * This needs to be done after sysctl_init, otherwise sys/ will be
 778  * overwritten.  Actually, this shouldn't be in sys/ at all since
 779  * it isn't a sysctl, and it doesn't contain sysctl information.
 780  * We now locate it in /proc/cpu/alignment instead.
 781  */
 782 static int __init alignment_init(void)
 783 {
 784 #ifdef CONFIG_PROC_FS
 785         struct proc_dir_entry *res;
 786
 787         res = proc_mkdir("cpu", NULL);
 788         if (!res)
 789                 return -ENOMEM;
 790
 791         res = create_proc_entry("alignment", S_IWUSR | S_IRUGO, res);
 792         if (!res)
 793                 return -ENOMEM;
 794
 795         res->read_proc = proc_alignment_read;
 796         res->write_proc = proc_alignment_write;
 797 #endif
 798
 799         hook_fault_code(1, do_alignment, SIGILL, "alignment exception");
 800         hook_fault_code(3, do_alignment, SIGILL, "alignment exception");
 801
 802         return 0;
 803 }
 804
 805 fs_initcall(alignment_init);