linux/arch/unicore32/mm/alignment.c
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   1/*
   2 * linux/arch/unicore32/mm/alignment.c
   3 *
   4 * Code specific to PKUnity SoC and UniCore ISA
   5 *
   6 * Copyright (C) 2001-2010 GUAN Xue-tao
   7 *
   8 * This program is free software; you can redistribute it and/or modify
   9 * it under the terms of the GNU General Public License version 2 as
  10 * published by the Free Software Foundation.
  11 */
  12/*
  13 * TODO:
  14 *  FPU ldm/stm not handling
  15 */
  16#include <linux/compiler.h>
  17#include <linux/kernel.h>
  18#include <linux/errno.h>
  19#include <linux/string.h>
  20#include <linux/init.h>
  21#include <linux/sched.h>
  22#include <linux/uaccess.h>
  23
  24#include <asm/pgtable.h>
  25#include <asm/tlbflush.h>
  26#include <asm/unaligned.h>
  27
  28#include "mm.h"
  29
  30#define CODING_BITS(i)  (i & 0xe0000120)
  31
  32#define LDST_P_BIT(i)   (i & (1 << 28)) /* Preindex             */
  33#define LDST_U_BIT(i)   (i & (1 << 27)) /* Add offset           */
  34#define LDST_W_BIT(i)   (i & (1 << 25)) /* Writeback            */
  35#define LDST_L_BIT(i)   (i & (1 << 24)) /* Load                 */
  36
  37#define LDST_P_EQ_U(i)  ((((i) ^ ((i) >> 1)) & (1 << 27)) == 0)
  38
  39#define LDSTH_I_BIT(i)  (i & (1 << 26)) /* half-word immed      */
  40#define LDM_S_BIT(i)    (i & (1 << 26)) /* write ASR from BSR */
  41#define LDM_H_BIT(i)    (i & (1 << 6))  /* select r0-r15 or r16-r31 */
  42
  43#define RN_BITS(i)      ((i >> 19) & 31)        /* Rn                   */
  44#define RD_BITS(i)      ((i >> 14) & 31)        /* Rd                   */
  45#define RM_BITS(i)      (i & 31)        /* Rm                   */
  46
  47#define REGMASK_BITS(i) (((i & 0x7fe00) >> 3) | (i & 0x3f))
  48#define OFFSET_BITS(i)  (i & 0x03fff)
  49
  50#define SHIFT_BITS(i)   ((i >> 9) & 0x1f)
  51#define SHIFT_TYPE(i)   (i & 0xc0)
  52#define SHIFT_LSL       0x00
  53#define SHIFT_LSR       0x40
  54#define SHIFT_ASR       0x80
  55#define SHIFT_RORRRX    0xc0
  56
  57union offset_union {
  58        unsigned long un;
  59        signed long sn;
  60};
  61
  62#define TYPE_ERROR      0
  63#define TYPE_FAULT      1
  64#define TYPE_LDST       2
  65#define TYPE_DONE       3
  66#define TYPE_SWAP  4
  67#define TYPE_COLS  5            /* Coprocessor load/store */
  68
  69#define get8_unaligned_check(val, addr, err)            \
  70        __asm__(                                        \
  71        "1:     ldb.u   %1, [%2], #1\n"                 \
  72        "2:\n"                                          \
  73        "       .pushsection .fixup,\"ax\"\n"           \
  74        "       .align  2\n"                            \
  75        "3:     mov     %0, #1\n"                       \
  76        "       b       2b\n"                           \
  77        "       .popsection\n"                          \
  78        "       .pushsection __ex_table,\"a\"\n"                \
  79        "       .align  3\n"                            \
  80        "       .long   1b, 3b\n"                       \
  81        "       .popsection\n"                          \
  82        : "=r" (err), "=&r" (val), "=r" (addr)          \
  83        : "0" (err), "2" (addr))
  84
  85#define get8t_unaligned_check(val, addr, err)           \
  86        __asm__(                                        \
  87        "1:     ldb.u   %1, [%2], #1\n"                 \
  88        "2:\n"                                          \
  89        "       .pushsection .fixup,\"ax\"\n"           \
  90        "       .align  2\n"                            \
  91        "3:     mov     %0, #1\n"                       \
  92        "       b       2b\n"                           \
  93        "       .popsection\n"                          \
  94        "       .pushsection __ex_table,\"a\"\n"                \
  95        "       .align  3\n"                            \
  96        "       .long   1b, 3b\n"                       \
  97        "       .popsection\n"                          \
  98        : "=r" (err), "=&r" (val), "=r" (addr)          \
  99        : "0" (err), "2" (addr))
 100
 101#define get16_unaligned_check(val, addr)                        \
 102        do {                                                    \
 103                unsigned int err = 0, v, a = addr;              \
 104                get8_unaligned_check(val, a, err);              \
 105                get8_unaligned_check(v, a, err);                \
 106                val |= v << 8;                                  \
 107                if (err)                                        \
 108                        goto fault;                             \
 109        } while (0)
 110
 111#define put16_unaligned_check(val, addr)                        \
 112        do {                                                    \
 113                unsigned int err = 0, v = val, a = addr;        \
 114                __asm__(                                        \
 115                "1:     stb.u   %1, [%2], #1\n"                 \
 116                "       mov     %1, %1 >> #8\n"                 \
 117                "2:     stb.u   %1, [%2]\n"                     \
 118                "3:\n"                                          \
 119                "       .pushsection .fixup,\"ax\"\n"           \
 120                "       .align  2\n"                            \
 121                "4:     mov     %0, #1\n"                       \
 122                "       b       3b\n"                           \
 123                "       .popsection\n"                          \
 124                "       .pushsection __ex_table,\"a\"\n"                \
 125                "       .align  3\n"                            \
 126                "       .long   1b, 4b\n"                       \
 127                "       .long   2b, 4b\n"                       \
 128                "       .popsection\n"                          \
 129                : "=r" (err), "=&r" (v), "=&r" (a)              \
 130                : "0" (err), "1" (v), "2" (a));                 \
 131                if (err)                                        \
 132                        goto fault;                             \
 133        } while (0)
 134
 135#define __put32_unaligned_check(ins, val, addr)                 \
 136        do {                                                    \
 137                unsigned int err = 0, v = val, a = addr;        \
 138                __asm__(                                        \
 139                "1:     "ins"   %1, [%2], #1\n"                 \
 140                "       mov     %1, %1 >> #8\n"                 \
 141                "2:     "ins"   %1, [%2], #1\n"                 \
 142                "       mov     %1, %1 >> #8\n"                 \
 143                "3:     "ins"   %1, [%2], #1\n"                 \
 144                "       mov     %1, %1 >> #8\n"                 \
 145                "4:     "ins"   %1, [%2]\n"                     \
 146                "5:\n"                                          \
 147                "       .pushsection .fixup,\"ax\"\n"           \
 148                "       .align  2\n"                            \
 149                "6:     mov     %0, #1\n"                       \
 150                "       b       5b\n"                           \
 151                "       .popsection\n"                          \
 152                "       .pushsection __ex_table,\"a\"\n"                \
 153                "       .align  3\n"                            \
 154                "       .long   1b, 6b\n"                       \
 155                "       .long   2b, 6b\n"                       \
 156                "       .long   3b, 6b\n"                       \
 157                "       .long   4b, 6b\n"                       \
 158                "       .popsection\n"                          \
 159                : "=r" (err), "=&r" (v), "=&r" (a)              \
 160                : "0" (err), "1" (v), "2" (a));                 \
 161                if (err)                                        \
 162                        goto fault;                             \
 163        } while (0)
 164
 165#define get32_unaligned_check(val, addr)                        \
 166        do {                                                    \
 167                unsigned int err = 0, v, a = addr;              \
 168                get8_unaligned_check(val, a, err);              \
 169                get8_unaligned_check(v, a, err);                \
 170                val |= v << 8;                                  \
 171                get8_unaligned_check(v, a, err);                \
 172                val |= v << 16;                                 \
 173                get8_unaligned_check(v, a, err);                \
 174                val |= v << 24;                                 \
 175                if (err)                                        \
 176                        goto fault;                             \
 177        } while (0)
 178
 179#define put32_unaligned_check(val, addr)                        \
 180        __put32_unaligned_check("stb.u", val, addr)
 181
 182#define get32t_unaligned_check(val, addr)                       \
 183        do {                                                    \
 184                unsigned int err = 0, v, a = addr;              \
 185                get8t_unaligned_check(val, a, err);             \
 186                get8t_unaligned_check(v, a, err);               \
 187                val |= v << 8;                                  \
 188                get8t_unaligned_check(v, a, err);               \
 189                val |= v << 16;                                 \
 190                get8t_unaligned_check(v, a, err);               \
 191                val |= v << 24;                                 \
 192                if (err)                                        \
 193                        goto fault;                             \
 194        } while (0)
 195
 196#define put32t_unaligned_check(val, addr)                       \
 197        __put32_unaligned_check("stb.u", val, addr)
 198
 199static void
 200do_alignment_finish_ldst(unsigned long addr, unsigned long instr,
 201                         struct pt_regs *regs, union offset_union offset)
 202{
 203        if (!LDST_U_BIT(instr))
 204                offset.un = -offset.un;
 205
 206        if (!LDST_P_BIT(instr))
 207                addr += offset.un;
 208
 209        if (!LDST_P_BIT(instr) || LDST_W_BIT(instr))
 210                regs->uregs[RN_BITS(instr)] = addr;
 211}
 212
 213static int
 214do_alignment_ldrhstrh(unsigned long addr, unsigned long instr,
 215                      struct pt_regs *regs)
 216{
 217        unsigned int rd = RD_BITS(instr);
 218
 219        /* old value 0x40002120, can't judge swap instr correctly */
 220        if ((instr & 0x4b003fe0) == 0x40000120)
 221                goto swp;
 222
 223        if (LDST_L_BIT(instr)) {
 224                unsigned long val;
 225                get16_unaligned_check(val, addr);
 226
 227                /* signed half-word? */
 228                if (instr & 0x80)
 229                        val = (signed long)((signed short)val);
 230
 231                regs->uregs[rd] = val;
 232        } else
 233                put16_unaligned_check(regs->uregs[rd], addr);
 234
 235        return TYPE_LDST;
 236
 237swp:
 238        /* only handle swap word
 239         * for swap byte should not active this alignment exception */
 240        get32_unaligned_check(regs->uregs[RD_BITS(instr)], addr);
 241        put32_unaligned_check(regs->uregs[RM_BITS(instr)], addr);
 242        return TYPE_SWAP;
 243
 244fault:
 245        return TYPE_FAULT;
 246}
 247
 248static int
 249do_alignment_ldrstr(unsigned long addr, unsigned long instr,
 250                    struct pt_regs *regs)
 251{
 252        unsigned int rd = RD_BITS(instr);
 253
 254        if (!LDST_P_BIT(instr) && LDST_W_BIT(instr))
 255                goto trans;
 256
 257        if (LDST_L_BIT(instr))
 258                get32_unaligned_check(regs->uregs[rd], addr);
 259        else
 260                put32_unaligned_check(regs->uregs[rd], addr);
 261        return TYPE_LDST;
 262
 263trans:
 264        if (LDST_L_BIT(instr))
 265                get32t_unaligned_check(regs->uregs[rd], addr);
 266        else
 267                put32t_unaligned_check(regs->uregs[rd], addr);
 268        return TYPE_LDST;
 269
 270fault:
 271        return TYPE_FAULT;
 272}
 273
 274/*
 275 * LDM/STM alignment handler.
 276 *
 277 * There are 4 variants of this instruction:
 278 *
 279 * B = rn pointer before instruction, A = rn pointer after instruction
 280 *              ------ increasing address ----->
 281 *              |    | r0 | r1 | ... | rx |    |
 282 * PU = 01             B                    A
 283 * PU = 11        B                    A
 284 * PU = 00        A                    B
 285 * PU = 10             A                    B
 286 */
 287static int
 288do_alignment_ldmstm(unsigned long addr, unsigned long instr,
 289                    struct pt_regs *regs)
 290{
 291        unsigned int rd, rn, pc_correction, reg_correction, nr_regs, regbits;
 292        unsigned long eaddr, newaddr;
 293
 294        if (LDM_S_BIT(instr))
 295                goto bad;
 296
 297        pc_correction = 4;      /* processor implementation defined */
 298
 299        /* count the number of registers in the mask to be transferred */
 300        nr_regs = hweight16(REGMASK_BITS(instr)) * 4;
 301
 302        rn = RN_BITS(instr);
 303        newaddr = eaddr = regs->uregs[rn];
 304
 305        if (!LDST_U_BIT(instr))
 306                nr_regs = -nr_regs;
 307        newaddr += nr_regs;
 308        if (!LDST_U_BIT(instr))
 309                eaddr = newaddr;
 310
 311        if (LDST_P_EQ_U(instr)) /* U = P */
 312                eaddr += 4;
 313
 314        /*
 315         * This is a "hint" - we already have eaddr worked out by the
 316         * processor for us.
 317         */
 318        if (addr != eaddr) {
 319                printk(KERN_ERR "LDMSTM: PC = %08lx, instr = %08lx, "
 320                       "addr = %08lx, eaddr = %08lx\n",
 321                       instruction_pointer(regs), instr, addr, eaddr);
 322                show_regs(regs);
 323        }
 324
 325        if (LDM_H_BIT(instr))
 326                reg_correction = 0x10;
 327        else
 328                reg_correction = 0x00;
 329
 330        for (regbits = REGMASK_BITS(instr), rd = 0; regbits;
 331             regbits >>= 1, rd += 1)
 332                if (regbits & 1) {
 333                        if (LDST_L_BIT(instr))
 334                                get32_unaligned_check(regs->
 335                                        uregs[rd + reg_correction], eaddr);
 336                        else
 337                                put32_unaligned_check(regs->
 338                                        uregs[rd + reg_correction], eaddr);
 339                        eaddr += 4;
 340                }
 341
 342        if (LDST_W_BIT(instr))
 343                regs->uregs[rn] = newaddr;
 344        return TYPE_DONE;
 345
 346fault:
 347        regs->UCreg_pc -= pc_correction;
 348        return TYPE_FAULT;
 349
 350bad:
 351        printk(KERN_ERR "Alignment trap: not handling ldm with s-bit set\n");
 352        return TYPE_ERROR;
 353}
 354
 355static int
 356do_alignment(unsigned long addr, unsigned int error_code, struct pt_regs *regs)
 357{
 358        union offset_union offset;
 359        unsigned long instr, instrptr;
 360        int (*handler) (unsigned long addr, unsigned long instr,
 361                        struct pt_regs *regs);
 362        unsigned int type;
 363
 364        instrptr = instruction_pointer(regs);
 365        if (instrptr >= PAGE_OFFSET)
 366                instr = *(unsigned long *)instrptr;
 367        else {
 368                __asm__ __volatile__(
 369                                "ldw.u  %0, [%1]\n"
 370                                : "=&r"(instr)
 371                                : "r"(instrptr));
 372        }
 373
 374        regs->UCreg_pc += 4;
 375
 376        switch (CODING_BITS(instr)) {
 377        case 0x40000120:        /* ldrh or strh */
 378                if (LDSTH_I_BIT(instr))
 379                        offset.un = (instr & 0x3e00) >> 4 | (instr & 31);
 380                else
 381                        offset.un = regs->uregs[RM_BITS(instr)];
 382                handler = do_alignment_ldrhstrh;
 383                break;
 384
 385        case 0x60000000:        /* ldr or str immediate */
 386        case 0x60000100:        /* ldr or str immediate */
 387        case 0x60000020:        /* ldr or str immediate */
 388        case 0x60000120:        /* ldr or str immediate */
 389                offset.un = OFFSET_BITS(instr);
 390                handler = do_alignment_ldrstr;
 391                break;
 392
 393        case 0x40000000:        /* ldr or str register */
 394                offset.un = regs->uregs[RM_BITS(instr)];
 395                {
 396                        unsigned int shiftval = SHIFT_BITS(instr);
 397
 398                        switch (SHIFT_TYPE(instr)) {
 399                        case SHIFT_LSL:
 400                                offset.un <<= shiftval;
 401                                break;
 402
 403                        case SHIFT_LSR:
 404                                offset.un >>= shiftval;
 405                                break;
 406
 407                        case SHIFT_ASR:
 408                                offset.sn >>= shiftval;
 409                                break;
 410
 411                        case SHIFT_RORRRX:
 412                                if (shiftval == 0) {
 413                                        offset.un >>= 1;
 414                                        if (regs->UCreg_asr & PSR_C_BIT)
 415                                                offset.un |= 1 << 31;
 416                                } else
 417                                        offset.un = offset.un >> shiftval |
 418                                            offset.un << (32 - shiftval);
 419                                break;
 420                        }
 421                }
 422                handler = do_alignment_ldrstr;
 423                break;
 424
 425        case 0x80000000:        /* ldm or stm */
 426        case 0x80000020:        /* ldm or stm */
 427                handler = do_alignment_ldmstm;
 428                break;
 429
 430        default:
 431                goto bad;
 432        }
 433
 434        type = handler(addr, instr, regs);
 435
 436        if (type == TYPE_ERROR || type == TYPE_FAULT)
 437                goto bad_or_fault;
 438
 439        if (type == TYPE_LDST)
 440                do_alignment_finish_ldst(addr, instr, regs, offset);
 441
 442        return 0;
 443
 444bad_or_fault:
 445        if (type == TYPE_ERROR)
 446                goto bad;
 447        regs->UCreg_pc -= 4;
 448        /*
 449         * We got a fault - fix it up, or die.
 450         */
 451        do_bad_area(addr, error_code, regs);
 452        return 0;
 453
 454bad:
 455        /*
 456         * Oops, we didn't handle the instruction.
 457         * However, we must handle fpu instr firstly.
 458         */
 459#ifdef CONFIG_UNICORE_FPU_F64
 460        /* handle co.load/store */
 461#define CODING_COLS                0xc0000000
 462#define COLS_OFFSET_BITS(i)     (i & 0x1FF)
 463#define COLS_L_BITS(i)          (i & (1<<24))
 464#define COLS_FN_BITS(i)         ((i>>14) & 31)
 465        if ((instr & 0xe0000000) == CODING_COLS) {
 466                unsigned int fn = COLS_FN_BITS(instr);
 467                unsigned long val = 0;
 468                if (COLS_L_BITS(instr)) {
 469                        get32t_unaligned_check(val, addr);
 470                        switch (fn) {
 471#define ASM_MTF(n)      case n:                                         \
 472                        __asm__ __volatile__("MTF %0, F" __stringify(n) \
 473                                : : "r"(val));                          \
 474                        break;
 475                        ASM_MTF(0); ASM_MTF(1); ASM_MTF(2); ASM_MTF(3);
 476                        ASM_MTF(4); ASM_MTF(5); ASM_MTF(6); ASM_MTF(7);
 477                        ASM_MTF(8); ASM_MTF(9); ASM_MTF(10); ASM_MTF(11);
 478                        ASM_MTF(12); ASM_MTF(13); ASM_MTF(14); ASM_MTF(15);
 479                        ASM_MTF(16); ASM_MTF(17); ASM_MTF(18); ASM_MTF(19);
 480                        ASM_MTF(20); ASM_MTF(21); ASM_MTF(22); ASM_MTF(23);
 481                        ASM_MTF(24); ASM_MTF(25); ASM_MTF(26); ASM_MTF(27);
 482                        ASM_MTF(28); ASM_MTF(29); ASM_MTF(30); ASM_MTF(31);
 483#undef ASM_MTF
 484                        }
 485                } else {
 486                        switch (fn) {
 487#define ASM_MFF(n)      case n:                                         \
 488                        __asm__ __volatile__("MFF %0, F" __stringify(n) \
 489                                : : "r"(val));                          \
 490                        break;
 491                        ASM_MFF(0); ASM_MFF(1); ASM_MFF(2); ASM_MFF(3);
 492                        ASM_MFF(4); ASM_MFF(5); ASM_MFF(6); ASM_MFF(7);
 493                        ASM_MFF(8); ASM_MFF(9); ASM_MFF(10); ASM_MFF(11);
 494                        ASM_MFF(12); ASM_MFF(13); ASM_MFF(14); ASM_MFF(15);
 495                        ASM_MFF(16); ASM_MFF(17); ASM_MFF(18); ASM_MFF(19);
 496                        ASM_MFF(20); ASM_MFF(21); ASM_MFF(22); ASM_MFF(23);
 497                        ASM_MFF(24); ASM_MFF(25); ASM_MFF(26); ASM_MFF(27);
 498                        ASM_MFF(28); ASM_MFF(29); ASM_MFF(30); ASM_MFF(31);
 499#undef ASM_MFF
 500                        }
 501                        put32t_unaligned_check(val, addr);
 502                }
 503                return TYPE_COLS;
 504        }
 505fault:
 506        return TYPE_FAULT;
 507#endif
 508        printk(KERN_ERR "Alignment trap: not handling instruction "
 509               "%08lx at [<%08lx>]\n", instr, instrptr);
 510        return 1;
 511}
 512
 513/*
 514 * This needs to be done after sysctl_init, otherwise sys/ will be
 515 * overwritten.  Actually, this shouldn't be in sys/ at all since
 516 * it isn't a sysctl, and it doesn't contain sysctl information.
 517 */
 518static int __init alignment_init(void)
 519{
 520        hook_fault_code(1, do_alignment, SIGBUS, BUS_ADRALN,
 521                        "alignment exception");
 522
 523        return 0;
 524}
 525
 526fs_initcall(alignment_init);
 527