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