arch/sparc64/kernel/unaligned.c

   1 /* $Id: unaligned.c,v 1.24 2002/02/09 19:49:31 davem Exp $
   2  * unaligned.c: Unaligned load/store trap handling with special
   3  *              cases for the kernel to do them more quickly.
   4  *
   5  * Copyright (C) 1996 David S. Miller (davem@caip.rutgers.edu)
   6  * Copyright (C) 1996,1997 Jakub Jelinek (jj@sunsite.mff.cuni.cz)
   7  */
   8
   9
  10 #include <linux/kernel.h>
  11 #include <linux/sched.h>
  12 #include <linux/mm.h>
  13 #include <linux/module.h>
  14 #include <asm/asi.h>
  15 #include <asm/ptrace.h>
  16 #include <asm/pstate.h>
  17 #include <asm/processor.h>
  18 #include <asm/system.h>
  19 #include <asm/uaccess.h>
  20 #include <linux/smp.h>
  21 #include <linux/smp_lock.h>
  22 #include <linux/bitops.h>
  23 #include <asm/fpumacro.h>
  24
  25 /* #define DEBUG_MNA */
  26
  27 enum direction {
  28         load,    /* ld, ldd, ldh, ldsh */
  29         store,   /* st, std, sth, stsh */
  30         both,    /* Swap, ldstub, cas, ... */
  31         fpld,
  32         fpst,
  33         invalid,
  34 };
  35
  36 #ifdef DEBUG_MNA
  37 static char *dirstrings[] = {
  38   "load", "store", "both", "fpload", "fpstore", "invalid"
  39 };
  40 #endif
  41
  42 static inline enum direction decode_direction(unsigned int insn)
  43 {
  44         unsigned long tmp = (insn >> 21) & 1;
  45
  46         if (!tmp)
  47                 return load;
  48         else {
  49                 switch ((insn>>19)&0xf) {
  50                 case 15: /* swap* */
  51                         return both;
  52                 default:
  53                         return store;
  54                 }
  55         }
  56 }
  57
  58 /* 16 = double-word, 8 = extra-word, 4 = word, 2 = half-word */
  59 static inline int decode_access_size(unsigned int insn)
  60 {
  61         unsigned int tmp;
  62
  63         tmp = ((insn >> 19) & 0xf);
  64         if (tmp == 11 || tmp == 14) /* ldx/stx */
  65                 return 8;
  66         tmp &= 3;
  67         if (!tmp)
  68                 return 4;
  69         else if (tmp == 3)
  70                 return 16;      /* ldd/std - Although it is actually 8 */
  71         else if (tmp == 2)
  72                 return 2;
  73         else {
  74                 printk("Impossible unaligned trap. insn=%08x\n", insn);
  75                 die_if_kernel("Byte sized unaligned access?!?!", current_thread_info()->kregs);
  76
  77                 /* GCC should never warn that control reaches the end
  78                  * of this function without returning a value because
  79                  * die_if_kernel() is marked with attribute 'noreturn'.
  80                  * Alas, some versions do...
  81                  */
  82
  83                 return 0;
  84         }
  85 }
  86
  87 static inline int decode_asi(unsigned int insn, struct pt_regs *regs)
  88 {
  89         if (insn & 0x800000) {
  90                 if (insn & 0x2000)
  91                         return (unsigned char)(regs->tstate >> 24);     /* %asi */
  92                 else
  93                         return (unsigned char)(insn >> 5);              /* imm_asi */
  94         } else
  95                 return ASI_P;
  96 }
  97
  98 /* 0x400000 = signed, 0 = unsigned */
  99 static inline int decode_signedness(unsigned int insn)
 100 {
 101         return (insn & 0x400000);
 102 }
 103
 104 static inline void maybe_flush_windows(unsigned int rs1, unsigned int rs2,
 105                                        unsigned int rd, int from_kernel)
 106 {
 107         if (rs2 >= 16 || rs1 >= 16 || rd >= 16) {
 108                 if (from_kernel != 0)
 109                         __asm__ __volatile__("flushw");
 110                 else
 111                         flushw_user();
 112         }
 113 }
 114
 115 static inline long sign_extend_imm13(long imm)
 116 {
 117         return imm << 51 >> 51;
 118 }
 119
 120 static unsigned long fetch_reg(unsigned int reg, struct pt_regs *regs)
 121 {
 122         unsigned long value;
 123
 124         if (reg < 16)
 125                 return (!reg ? 0 : regs->u_regs[reg]);
 126         if (regs->tstate & TSTATE_PRIV) {
 127                 struct reg_window *win;
 128                 win = (struct reg_window *)(regs->u_regs[UREG_FP] + STACK_BIAS);
 129                 value = win->locals[reg - 16];
 130         } else if (test_thread_flag(TIF_32BIT)) {
 131                 struct reg_window32 __user *win32;
 132                 win32 = (struct reg_window32 __user *)((unsigned long)((u32)regs->u_regs[UREG_FP]));
 133                 get_user(value, &win32->locals[reg - 16]);
 134         } else {
 135                 struct reg_window __user *win;
 136                 win = (struct reg_window __user *)(regs->u_regs[UREG_FP] + STACK_BIAS);
 137                 get_user(value, &win->locals[reg - 16]);
 138         }
 139         return value;
 140 }
 141
 142 static unsigned long *fetch_reg_addr(unsigned int reg, struct pt_regs *regs)
 143 {
 144         if (reg < 16)
 145                 return &regs->u_regs[reg];
 146         if (regs->tstate & TSTATE_PRIV) {
 147                 struct reg_window *win;
 148                 win = (struct reg_window *)(regs->u_regs[UREG_FP] + STACK_BIAS);
 149                 return &win->locals[reg - 16];
 150         } else if (test_thread_flag(TIF_32BIT)) {
 151                 struct reg_window32 *win32;
 152                 win32 = (struct reg_window32 *)((unsigned long)((u32)regs->u_regs[UREG_FP]));
 153                 return (unsigned long *)&win32->locals[reg - 16];
 154         } else {
 155                 struct reg_window *win;
 156                 win = (struct reg_window *)(regs->u_regs[UREG_FP] + STACK_BIAS);
 157                 return &win->locals[reg - 16];
 158         }
 159 }
 160
 161 unsigned long compute_effective_address(struct pt_regs *regs,
 162                                         unsigned int insn, unsigned int rd)
 163 {
 164         unsigned int rs1 = (insn >> 14) & 0x1f;
 165         unsigned int rs2 = insn & 0x1f;
 166         int from_kernel = (regs->tstate & TSTATE_PRIV) != 0;
 167
 168         if (insn & 0x2000) {
 169                 maybe_flush_windows(rs1, 0, rd, from_kernel);
 170                 return (fetch_reg(rs1, regs) + sign_extend_imm13(insn));
 171         } else {
 172                 maybe_flush_windows(rs1, rs2, rd, from_kernel);
 173                 return (fetch_reg(rs1, regs) + fetch_reg(rs2, regs));
 174         }
 175 }
 176
 177 /* This is just to make gcc think die_if_kernel does return... */
 178 static void __attribute_used__ unaligned_panic(char *str, struct pt_regs *regs)
 179 {
 180         die_if_kernel(str, regs);
 181 }
 182
 183 extern int do_int_load(unsigned long *dest_reg, int size,
 184                        unsigned long *saddr, int is_signed, int asi);
 185
 186 extern int __do_int_store(unsigned long *dst_addr, int size,
 187                           unsigned long src_val, int asi);
 188
 189 static inline int do_int_store(int reg_num, int size, unsigned long *dst_addr,
 190                                struct pt_regs *regs, int asi, int orig_asi)
 191 {
 192         unsigned long zero = 0;
 193         unsigned long *src_val_p = &zero;
 194         unsigned long src_val;
 195
 196         if (size == 16) {
 197                 size = 8;
 198                 zero = (((long)(reg_num ?
 199                         (unsigned)fetch_reg(reg_num, regs) : 0)) << 32) |
 200                         (unsigned)fetch_reg(reg_num + 1, regs);
 201         } else if (reg_num) {
 202                 src_val_p = fetch_reg_addr(reg_num, regs);
 203         }
 204         src_val = *src_val_p;
 205         if (unlikely(asi != orig_asi)) {
 206                 switch (size) {
 207                 case 2:
 208                         src_val = swab16(src_val);
 209                         break;
 210                 case 4:
 211                         src_val = swab32(src_val);
 212                         break;
 213                 case 8:
 214                         src_val = swab64(src_val);
 215                         break;
 216                 case 16:
 217                 default:
 218                         BUG();
 219                         break;
 220                 };
 221         }
 222         return __do_int_store(dst_addr, size, src_val, asi);
 223 }
 224
 225 static inline void advance(struct pt_regs *regs)
 226 {
 227         regs->tpc   = regs->tnpc;
 228         regs->tnpc += 4;
 229         if (test_thread_flag(TIF_32BIT)) {
 230                 regs->tpc &= 0xffffffff;
 231                 regs->tnpc &= 0xffffffff;
 232         }
 233 }
 234
 235 static inline int floating_point_load_or_store_p(unsigned int insn)
 236 {
 237         return (insn >> 24) & 1;
 238 }
 239
 240 static inline int ok_for_kernel(unsigned int insn)
 241 {
 242         return !floating_point_load_or_store_p(insn);
 243 }
 244
 245 static void kernel_mna_trap_fault(void)
 246 {
 247         struct pt_regs *regs = current_thread_info()->kern_una_regs;
 248         unsigned int insn = current_thread_info()->kern_una_insn;
 249         const struct exception_table_entry *entry;
 250
 251         entry = search_exception_tables(regs->tpc);
 252         if (!entry) {
 253                 unsigned long address;
 254
 255                 address = compute_effective_address(regs, insn,
 256                                                     ((insn >> 25) & 0x1f));
 257                 if (address < PAGE_SIZE) {
 258                         printk(KERN_ALERT "Unable to handle kernel NULL "
 259                                "pointer dereference in mna handler");
 260                 } else
 261                         printk(KERN_ALERT "Unable to handle kernel paging "
 262                                "request in mna handler");
 263                 printk(KERN_ALERT " at virtual address %016lx\n",address);
 264                 printk(KERN_ALERT "current->{active_,}mm->context = %016lx\n",
 265                         (current->mm ? CTX_HWBITS(current->mm->context) :
 266                         CTX_HWBITS(current->active_mm->context)));
 267                 printk(KERN_ALERT "current->{active_,}mm->pgd = %016lx\n",
 268                         (current->mm ? (unsigned long) current->mm->pgd :
 269                         (unsigned long) current->active_mm->pgd));
 270                 die_if_kernel("Oops", regs);
 271                 /* Not reached */
 272         }
 273         regs->tpc = entry->fixup;
 274         regs->tnpc = regs->tpc + 4;
 275
 276         regs->tstate &= ~TSTATE_ASI;
 277         regs->tstate |= (ASI_AIUS << 24UL);
 278 }
 279
 280 asmlinkage void kernel_unaligned_trap(struct pt_regs *regs, unsigned int insn)
 281 {
 282         static unsigned long count, last_time;
 283         enum direction dir = decode_direction(insn);
 284         int size = decode_access_size(insn);
 285
 286         current_thread_info()->kern_una_regs = regs;
 287         current_thread_info()->kern_una_insn = insn;
 288
 289         if (jiffies - last_time > 5 * HZ)
 290                 count = 0;
 291         if (count < 5) {
 292                 last_time = jiffies;
 293                 count++;
 294                 printk("Kernel unaligned access at TPC[%lx]\n", regs->tpc);
 295         }
 296
 297         if (!ok_for_kernel(insn) || dir == both) {
 298                 printk("Unsupported unaligned load/store trap for kernel "
 299                        "at <%016lx>.\n", regs->tpc);
 300                 unaligned_panic("Kernel does fpu/atomic "
 301                                 "unaligned load/store.", regs);
 302
 303                 kernel_mna_trap_fault();
 304         } else {
 305                 unsigned long addr, *reg_addr;
 306                 int orig_asi, asi, err;
 307
 308                 addr = compute_effective_address(regs, insn,
 309                                                  ((insn >> 25) & 0x1f));
 310 #ifdef DEBUG_MNA
 311                 printk("KMNA: pc=%016lx [dir=%s addr=%016lx size=%d] "
 312                        "retpc[%016lx]\n",
 313                        regs->tpc, dirstrings[dir], addr, size,
 314                        regs->u_regs[UREG_RETPC]);
 315 #endif
 316                 orig_asi = asi = decode_asi(insn, regs);
 317                 switch (asi) {
 318                 case ASI_NL:
 319                 case ASI_AIUPL:
 320                 case ASI_AIUSL:
 321                 case ASI_PL:
 322                 case ASI_SL:
 323                 case ASI_PNFL:
 324                 case ASI_SNFL:
 325                         asi &= ~0x08;
 326                         break;
 327                 };
 328                 switch (dir) {
 329                 case load:
 330                         reg_addr = fetch_reg_addr(((insn>>25)&0x1f), regs);
 331                         err = do_int_load(reg_addr, size,
 332                                           (unsigned long *) addr,
 333                                           decode_signedness(insn), asi);
 334                         if (likely(!err) && unlikely(asi != orig_asi)) {
 335                                 unsigned long val_in = *reg_addr;
 336                                 switch (size) {
 337                                 case 2:
 338                                         val_in = swab16(val_in);
 339                                         break;
 340                                 case 4:
 341                                         val_in = swab32(val_in);
 342                                         break;
 343                                 case 8:
 344                                         val_in = swab64(val_in);
 345                                         break;
 346                                 case 16:
 347                                 default:
 348                                         BUG();
 349                                         break;
 350                                 };
 351                                 *reg_addr = val_in;
 352                         }
 353                         break;
 354
 355                 case store:
 356                         err = do_int_store(((insn>>25)&0x1f), size,
 357                                            (unsigned long *) addr, regs,
 358                                            asi, orig_asi);
 359                         break;
 360
 361                 default:
 362                         panic("Impossible kernel unaligned trap.");
 363                         /* Not reached... */
 364                 }
 365                 if (unlikely(err))
 366                         kernel_mna_trap_fault();
 367                 else
 368                         advance(regs);
 369         }
 370 }
 371
 372 static char popc_helper[] = {
 373 0, 1, 1, 2, 1, 2, 2, 3,
 374 1, 2, 2, 3, 2, 3, 3, 4,
 375 };
 376
 377 int handle_popc(u32 insn, struct pt_regs *regs)
 378 {
 379         u64 value;
 380         int ret, i, rd = ((insn >> 25) & 0x1f);
 381         int from_kernel = (regs->tstate & TSTATE_PRIV) != 0;
 382
 383         if (insn & 0x2000) {
 384                 maybe_flush_windows(0, 0, rd, from_kernel);
 385                 value = sign_extend_imm13(insn);
 386         } else {
 387                 maybe_flush_windows(0, insn & 0x1f, rd, from_kernel);
 388                 value = fetch_reg(insn & 0x1f, regs);
 389         }
 390         for (ret = 0, i = 0; i < 16; i++) {
 391                 ret += popc_helper[value & 0xf];
 392                 value >>= 4;
 393         }
 394         if (rd < 16) {
 395                 if (rd)
 396                         regs->u_regs[rd] = ret;
 397         } else {
 398                 if (test_thread_flag(TIF_32BIT)) {
 399                         struct reg_window32 __user *win32;
 400                         win32 = (struct reg_window32 __user *)((unsigned long)((u32)regs->u_regs[UREG_FP]));
 401                         put_user(ret, &win32->locals[rd - 16]);
 402                 } else {
 403                         struct reg_window __user *win;
 404                         win = (struct reg_window __user *)(regs->u_regs[UREG_FP] + STACK_BIAS);
 405                         put_user(ret, &win->locals[rd - 16]);
 406                 }
 407         }
 408         advance(regs);
 409         return 1;
 410 }
 411
 412 extern void do_fpother(struct pt_regs *regs);
 413 extern void do_privact(struct pt_regs *regs);
 414 extern void spitfire_data_access_exception(struct pt_regs *regs,
 415                                            unsigned long sfsr,
 416                                            unsigned long sfar);
 417 extern void sun4v_data_access_exception(struct pt_regs *regs,
 418                                         unsigned long addr,
 419                                         unsigned long type_ctx);
 420
 421 int handle_ldf_stq(u32 insn, struct pt_regs *regs)
 422 {
 423         unsigned long addr = compute_effective_address(regs, insn, 0);
 424         int freg = ((insn >> 25) & 0x1e) | ((insn >> 20) & 0x20);
 425         struct fpustate *f = FPUSTATE;
 426         int asi = decode_asi(insn, regs);
 427         int flag = (freg < 32) ? FPRS_DL : FPRS_DU;
 428
 429         save_and_clear_fpu();
 430         current_thread_info()->xfsr[0] &= ~0x1c000;
 431         if (freg & 3) {
 432                 current_thread_info()->xfsr[0] |= (6 << 14) /* invalid_fp_register */;
 433                 do_fpother(regs);
 434                 return 0;
 435         }
 436         if (insn & 0x200000) {
 437                 /* STQ */
 438                 u64 first = 0, second = 0;
 439
 440                 if (current_thread_info()->fpsaved[0] & flag) {
 441                         first = *(u64 *)&f->regs[freg];
 442                         second = *(u64 *)&f->regs[freg+2];
 443                 }
 444                 if (asi < 0x80) {
 445                         do_privact(regs);
 446                         return 1;
 447                 }
 448                 switch (asi) {
 449                 case ASI_P:
 450                 case ASI_S: break;
 451                 case ASI_PL:
 452                 case ASI_SL:
 453                         {
 454                                 /* Need to convert endians */
 455                                 u64 tmp = __swab64p(&first);
 456
 457                                 first = __swab64p(&second);
 458                                 second = tmp;
 459                                 break;
 460                         }
 461                 default:
 462                         if (tlb_type == hypervisor)
 463                                 sun4v_data_access_exception(regs, addr, 0);
 464                         else
 465                                 spitfire_data_access_exception(regs, 0, addr);
 466                         return 1;
 467                 }
 468                 if (put_user (first >> 32, (u32 __user *)addr) ||
 469                     __put_user ((u32)first, (u32 __user *)(addr + 4)) ||
 470                     __put_user (second >> 32, (u32 __user *)(addr + 8)) ||
 471                     __put_user ((u32)second, (u32 __user *)(addr + 12))) {
 472                         if (tlb_type == hypervisor)
 473                                 sun4v_data_access_exception(regs, addr, 0);
 474                         else
 475                                 spitfire_data_access_exception(regs, 0, addr);
 476                         return 1;
 477                 }
 478         } else {
 479                 /* LDF, LDDF, LDQF */
 480                 u32 data[4] __attribute__ ((aligned(8)));
 481                 int size, i;
 482                 int err;
 483
 484                 if (asi < 0x80) {
 485                         do_privact(regs);
 486                         return 1;
 487                 } else if (asi > ASI_SNFL) {
 488                         if (tlb_type == hypervisor)
 489                                 sun4v_data_access_exception(regs, addr, 0);
 490                         else
 491                                 spitfire_data_access_exception(regs, 0, addr);
 492                         return 1;
 493                 }
 494                 switch (insn & 0x180000) {
 495                 case 0x000000: size = 1; break;
 496                 case 0x100000: size = 4; break;
 497                 default: size = 2; break;
 498                 }
 499                 for (i = 0; i < size; i++)
 500                         data[i] = 0;
 501
 502                 err = get_user (data[0], (u32 __user *) addr);
 503                 if (!err) {
 504                         for (i = 1; i < size; i++)
 505                                 err |= __get_user (data[i], (u32 __user *)(addr + 4*i));
 506                 }
 507                 if (err && !(asi & 0x2 /* NF */)) {
 508                         if (tlb_type == hypervisor)
 509                                 sun4v_data_access_exception(regs, addr, 0);
 510                         else
 511                                 spitfire_data_access_exception(regs, 0, addr);
 512                         return 1;
 513                 }
 514                 if (asi & 0x8) /* Little */ {
 515                         u64 tmp;
 516
 517                         switch (size) {
 518                         case 1: data[0] = le32_to_cpup(data + 0); break;
 519                         default:*(u64 *)(data + 0) = le64_to_cpup((u64 *)(data + 0));
 520                                 break;
 521                         case 4: tmp = le64_to_cpup((u64 *)(data + 0));
 522                                 *(u64 *)(data + 0) = le64_to_cpup((u64 *)(data + 2));
 523                                 *(u64 *)(data + 2) = tmp;
 524                                 break;
 525                         }
 526                 }
 527                 if (!(current_thread_info()->fpsaved[0] & FPRS_FEF)) {
 528                         current_thread_info()->fpsaved[0] = FPRS_FEF;
 529                         current_thread_info()->gsr[0] = 0;
 530                 }
 531                 if (!(current_thread_info()->fpsaved[0] & flag)) {
 532                         if (freg < 32)
 533                                 memset(f->regs, 0, 32*sizeof(u32));
 534                         else
 535                                 memset(f->regs+32, 0, 32*sizeof(u32));
 536                 }
 537                 memcpy(f->regs + freg, data, size * 4);
 538                 current_thread_info()->fpsaved[0] |= flag;
 539         }
 540         advance(regs);
 541         return 1;
 542 }
 543
 544 void handle_ld_nf(u32 insn, struct pt_regs *regs)
 545 {
 546         int rd = ((insn >> 25) & 0x1f);
 547         int from_kernel = (regs->tstate & TSTATE_PRIV) != 0;
 548         unsigned long *reg;
 549
 550         maybe_flush_windows(0, 0, rd, from_kernel);
 551         reg = fetch_reg_addr(rd, regs);
 552         if (from_kernel || rd < 16) {
 553                 reg[0] = 0;
 554                 if ((insn & 0x780000) == 0x180000)
 555                         reg[1] = 0;
 556         } else if (test_thread_flag(TIF_32BIT)) {
 557                 put_user(0, (int __user *) reg);
 558                 if ((insn & 0x780000) == 0x180000)
 559                         put_user(0, ((int __user *) reg) + 1);
 560         } else {
 561                 put_user(0, (unsigned long __user *) reg);
 562                 if ((insn & 0x780000) == 0x180000)
 563                         put_user(0, (unsigned long __user *) reg + 1);
 564         }
 565         advance(regs);
 566 }
 567
 568 void handle_lddfmna(struct pt_regs *regs, unsigned long sfar, unsigned long sfsr)
 569 {
 570         unsigned long pc = regs->tpc;
 571         unsigned long tstate = regs->tstate;
 572         u32 insn;
 573         u32 first, second;
 574         u64 value;
 575         u8 freg;
 576         int flag;
 577         struct fpustate *f = FPUSTATE;
 578
 579         if (tstate & TSTATE_PRIV)
 580                 die_if_kernel("lddfmna from kernel", regs);
 581         if (test_thread_flag(TIF_32BIT))
 582                 pc = (u32)pc;
 583         if (get_user(insn, (u32 __user *) pc) != -EFAULT) {
 584                 int asi = decode_asi(insn, regs);
 585                 if ((asi > ASI_SNFL) ||
 586                     (asi < ASI_P))
 587                         goto daex;
 588                 if (get_user(first, (u32 __user *)sfar) ||
 589                      get_user(second, (u32 __user *)(sfar + 4))) {
 590                         if (asi & 0x2) /* NF */ {
 591                                 first = 0; second = 0;
 592                         } else
 593                                 goto daex;
 594                 }
 595                 save_and_clear_fpu();
 596                 freg = ((insn >> 25) & 0x1e) | ((insn >> 20) & 0x20);
 597                 value = (((u64)first) << 32) | second;
 598                 if (asi & 0x8) /* Little */
 599                         value = __swab64p(&value);
 600                 flag = (freg < 32) ? FPRS_DL : FPRS_DU;
 601                 if (!(current_thread_info()->fpsaved[0] & FPRS_FEF)) {
 602                         current_thread_info()->fpsaved[0] = FPRS_FEF;
 603                         current_thread_info()->gsr[0] = 0;
 604                 }
 605                 if (!(current_thread_info()->fpsaved[0] & flag)) {
 606                         if (freg < 32)
 607                                 memset(f->regs, 0, 32*sizeof(u32));
 608                         else
 609                                 memset(f->regs+32, 0, 32*sizeof(u32));
 610                 }
 611                 *(u64 *)(f->regs + freg) = value;
 612                 current_thread_info()->fpsaved[0] |= flag;
 613         } else {
 614 daex:
 615                 if (tlb_type == hypervisor)
 616                         sun4v_data_access_exception(regs, sfar, sfsr);
 617                 else
 618                         spitfire_data_access_exception(regs, sfsr, sfar);
 619                 return;
 620         }
 621         advance(regs);
 622         return;
 623 }
 624
 625 void handle_stdfmna(struct pt_regs *regs, unsigned long sfar, unsigned long sfsr)
 626 {
 627         unsigned long pc = regs->tpc;
 628         unsigned long tstate = regs->tstate;
 629         u32 insn;
 630         u64 value;
 631         u8 freg;
 632         int flag;
 633         struct fpustate *f = FPUSTATE;
 634
 635         if (tstate & TSTATE_PRIV)
 636                 die_if_kernel("stdfmna from kernel", regs);
 637         if (test_thread_flag(TIF_32BIT))
 638                 pc = (u32)pc;
 639         if (get_user(insn, (u32 __user *) pc) != -EFAULT) {
 640                 int asi = decode_asi(insn, regs);
 641                 freg = ((insn >> 25) & 0x1e) | ((insn >> 20) & 0x20);
 642                 value = 0;
 643                 flag = (freg < 32) ? FPRS_DL : FPRS_DU;
 644                 if ((asi > ASI_SNFL) ||
 645                     (asi < ASI_P))
 646                         goto daex;
 647                 save_and_clear_fpu();
 648                 if (current_thread_info()->fpsaved[0] & flag)
 649                         value = *(u64 *)&f->regs[freg];
 650                 switch (asi) {
 651                 case ASI_P:
 652                 case ASI_S: break;
 653                 case ASI_PL:
 654                 case ASI_SL:
 655                         value = __swab64p(&value); break;
 656                 default: goto daex;
 657                 }
 658                 if (put_user (value >> 32, (u32 __user *) sfar) ||
 659                     __put_user ((u32)value, (u32 __user *)(sfar + 4)))
 660                         goto daex;
 661         } else {
 662 daex:
 663                 if (tlb_type == hypervisor)
 664                         sun4v_data_access_exception(regs, sfar, sfsr);
 665                 else
 666                         spitfire_data_access_exception(regs, sfsr, sfar);
 667                 return;
 668         }
 669         advance(regs);
 670         return;
 671 }