arch/sparc/kernel/unaligned.c

   1 /* $Id: unaligned.c,v 1.22.2.1 2001/12/21 00:52:47 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 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 <asm/ptrace.h>
  14 #include <asm/processor.h>
  15 #include <asm/system.h>
  16 #include <asm/uaccess.h>
  17 #include <linux/smp.h>
  18 #include <linux/smp_lock.h>
  19
  20 /* #define DEBUG_MNA */
  21
  22 enum direction {
  23         load,    /* ld, ldd, ldh, ldsh */
  24         store,   /* st, std, sth, stsh */
  25         both,    /* Swap, ldstub, etc. */
  26         fpload,
  27         fpstore,
  28         invalid,
  29 };
  30
  31 #ifdef DEBUG_MNA
  32 static char *dirstrings[] = {
  33   "load", "store", "both", "fpload", "fpstore", "invalid"
  34 };
  35 #endif
  36
  37 static inline enum direction decode_direction(unsigned int insn)
  38 {
  39         unsigned long tmp = (insn >> 21) & 1;
  40
  41         if(!tmp)
  42                 return load;
  43         else {
  44                 if(((insn>>19)&0x3f) == 15)
  45                         return both;
  46                 else
  47                         return store;
  48         }
  49 }
  50
  51 /* 8 = double-word, 4 = word, 2 = half-word */
  52 static inline int decode_access_size(unsigned int insn)
  53 {
  54         insn = (insn >> 19) & 3;
  55
  56         if(!insn)
  57                 return 4;
  58         else if(insn == 3)
  59                 return 8;
  60         else if(insn == 2)
  61                 return 2;
  62         else {
  63                 printk("Impossible unaligned trap. insn=%08x\n", insn);
  64                 die_if_kernel("Byte sized unaligned access?!?!", current->thread.kregs);
  65                 return 4; /* just to keep gcc happy. */
  66         }
  67 }
  68
  69 /* 0x400000 = signed, 0 = unsigned */
  70 static inline int decode_signedness(unsigned int insn)
  71 {
  72         return (insn & 0x400000);
  73 }
  74
  75 static inline void maybe_flush_windows(unsigned int rs1, unsigned int rs2,
  76                                        unsigned int rd)
  77 {
  78         if(rs2 >= 16 || rs1 >= 16 || rd >= 16) {
  79                 /* Wheee... */
  80                 __asm__ __volatile__("save %sp, -0x40, %sp\n\t"
  81                                      "save %sp, -0x40, %sp\n\t"
  82                                      "save %sp, -0x40, %sp\n\t"
  83                                      "save %sp, -0x40, %sp\n\t"
  84                                      "save %sp, -0x40, %sp\n\t"
  85                                      "save %sp, -0x40, %sp\n\t"
  86                                      "save %sp, -0x40, %sp\n\t"
  87                                      "restore; restore; restore; restore;\n\t"
  88                                      "restore; restore; restore;\n\t");
  89         }
  90 }
  91
  92 static inline int sign_extend_imm13(int imm)
  93 {
  94         return imm << 19 >> 19;
  95 }
  96
  97 static inline unsigned long fetch_reg(unsigned int reg, struct pt_regs *regs)
  98 {
  99         struct reg_window *win;
 100
 101         if(reg < 16)
 102                 return (!reg ? 0 : regs->u_regs[reg]);
 103
 104         /* Ho hum, the slightly complicated case. */
 105         win = (struct reg_window *) regs->u_regs[UREG_FP];
 106         return win->locals[reg - 16]; /* yes, I know what this does... */
 107 }
 108
 109 static inline unsigned long safe_fetch_reg(unsigned int reg, struct pt_regs *regs)
 110 {
 111         struct reg_window *win;
 112         unsigned long ret;
 113
 114         if(reg < 16)
 115                 return (!reg ? 0 : regs->u_regs[reg]);
 116
 117         /* Ho hum, the slightly complicated case. */
 118         win = (struct reg_window *) regs->u_regs[UREG_FP];
 119
 120         if ((unsigned long)win & 3)
 121                 return -1;
 122
 123         if (get_user(ret, &win->locals[reg - 16]))
 124                 return -1;
 125
 126         return ret;
 127 }
 128
 129 static inline unsigned long *fetch_reg_addr(unsigned int reg, struct pt_regs *regs)
 130 {
 131         struct reg_window *win;
 132
 133         if(reg < 16)
 134                 return &regs->u_regs[reg];
 135         win = (struct reg_window *) regs->u_regs[UREG_FP];
 136         return &win->locals[reg - 16];
 137 }
 138
 139 static unsigned long compute_effective_address(struct pt_regs *regs,
 140                                                unsigned int insn)
 141 {
 142         unsigned int rs1 = (insn >> 14) & 0x1f;
 143         unsigned int rs2 = insn & 0x1f;
 144         unsigned int rd = (insn >> 25) & 0x1f;
 145
 146         if(insn & 0x2000) {
 147                 maybe_flush_windows(rs1, 0, rd);
 148                 return (fetch_reg(rs1, regs) + sign_extend_imm13(insn));
 149         } else {
 150                 maybe_flush_windows(rs1, rs2, rd);
 151                 return (fetch_reg(rs1, regs) + fetch_reg(rs2, regs));
 152         }
 153 }
 154
 155 unsigned long safe_compute_effective_address(struct pt_regs *regs,
 156                                              unsigned int insn)
 157 {
 158         unsigned int rs1 = (insn >> 14) & 0x1f;
 159         unsigned int rs2 = insn & 0x1f;
 160         unsigned int rd = (insn >> 25) & 0x1f;
 161
 162         if(insn & 0x2000) {
 163                 maybe_flush_windows(rs1, 0, rd);
 164                 return (safe_fetch_reg(rs1, regs) + sign_extend_imm13(insn));
 165         } else {
 166                 maybe_flush_windows(rs1, rs2, rd);
 167                 return (safe_fetch_reg(rs1, regs) + safe_fetch_reg(rs2, regs));
 168         }
 169 }
 170
 171 /* This is just to make gcc think panic does return... */
 172 static void unaligned_panic(char *str)
 173 {
 174         panic(str);
 175 }
 176
 177 #define do_integer_load(dest_reg, size, saddr, is_signed, errh) ({              \
 178 __asm__ __volatile__ (                                                          \
 179         "cmp    %1, 8\n\t"                                                      \
 180         "be     9f\n\t"                                                         \
 181         " cmp   %1, 4\n\t"                                                      \
 182         "be     6f\n"                                                           \
 183 "4:\t"  " ldub  [%2], %%l1\n"                                                   \
 184 "5:\t"  "ldub   [%2 + 1], %%l2\n\t"                                             \
 185         "sll    %%l1, 8, %%l1\n\t"                                              \
 186         "tst    %3\n\t"                                                         \
 187         "be     3f\n\t"                                                         \
 188         " add   %%l1, %%l2, %%l1\n\t"                                           \
 189         "sll    %%l1, 16, %%l1\n\t"                                             \
 190         "sra    %%l1, 16, %%l1\n"                                               \
 191 "3:\t"  "b      0f\n\t"                                                         \
 192         " st    %%l1, [%0]\n"                                                   \
 193 "6:\t"  "ldub   [%2 + 1], %%l2\n\t"                                             \
 194         "sll    %%l1, 24, %%l1\n"                                               \
 195 "7:\t"  "ldub   [%2 + 2], %%g7\n\t"                                             \
 196         "sll    %%l2, 16, %%l2\n"                                               \
 197 "8:\t"  "ldub   [%2 + 3], %%g1\n\t"                                             \
 198         "sll    %%g7, 8, %%g7\n\t"                                              \
 199         "or     %%l1, %%l2, %%l1\n\t"                                           \
 200         "or     %%g7, %%g1, %%g7\n\t"                                           \
 201         "or     %%l1, %%g7, %%l1\n\t"                                           \
 202         "b      0f\n\t"                                                         \
 203         " st    %%l1, [%0]\n"                                                   \
 204 "9:\t"  "ldub   [%2], %%l1\n"                                                   \
 205 "10:\t" "ldub   [%2 + 1], %%l2\n\t"                                             \
 206         "sll    %%l1, 24, %%l1\n"                                               \
 207 "11:\t" "ldub   [%2 + 2], %%g7\n\t"                                             \
 208         "sll    %%l2, 16, %%l2\n"                                               \
 209 "12:\t" "ldub   [%2 + 3], %%g1\n\t"                                             \
 210         "sll    %%g7, 8, %%g7\n\t"                                              \
 211         "or     %%l1, %%l2, %%l1\n\t"                                           \
 212         "or     %%g7, %%g1, %%g7\n\t"                                           \
 213         "or     %%l1, %%g7, %%g7\n"                                             \
 214 "13:\t" "ldub   [%2 + 4], %%l1\n\t"                                             \
 215         "st     %%g7, [%0]\n"                                                   \
 216 "14:\t" "ldub   [%2 + 5], %%l2\n\t"                                             \
 217         "sll    %%l1, 24, %%l1\n"                                               \
 218 "15:\t" "ldub   [%2 + 6], %%g7\n\t"                                             \
 219         "sll    %%l2, 16, %%l2\n"                                               \
 220 "16:\t" "ldub   [%2 + 7], %%g1\n\t"                                             \
 221         "sll    %%g7, 8, %%g7\n\t"                                              \
 222         "or     %%l1, %%l2, %%l1\n\t"                                           \
 223         "or     %%g7, %%g1, %%g7\n\t"                                           \
 224         "or     %%l1, %%g7, %%g7\n\t"                                           \
 225         "st     %%g7, [%0 + 4]\n"                                               \
 226 "0:\n\n\t"                                                                      \
 227         ".section __ex_table,#alloc\n\t"                                        \
 228         ".word  4b, " #errh "\n\t"                                              \
 229         ".word  5b, " #errh "\n\t"                                              \
 230         ".word  6b, " #errh "\n\t"                                              \
 231         ".word  7b, " #errh "\n\t"                                              \
 232         ".word  8b, " #errh "\n\t"                                              \
 233         ".word  9b, " #errh "\n\t"                                              \
 234         ".word  10b, " #errh "\n\t"                                             \
 235         ".word  11b, " #errh "\n\t"                                             \
 236         ".word  12b, " #errh "\n\t"                                             \
 237         ".word  13b, " #errh "\n\t"                                             \
 238         ".word  14b, " #errh "\n\t"                                             \
 239         ".word  15b, " #errh "\n\t"                                             \
 240         ".word  16b, " #errh "\n\n\t"                                           \
 241         ".previous\n\t"                                                         \
 242         : : "r" (dest_reg), "r" (size), "r" (saddr), "r" (is_signed)            \
 243         : "l1", "l2", "g7", "g1", "cc");                                        \
 244 })
 245
 246 #define store_common(dst_addr, size, src_val, errh) ({                          \
 247 __asm__ __volatile__ (                                                          \
 248         "ld     [%2], %%l1\n"                                                   \
 249         "cmp    %1, 2\n\t"                                                      \
 250         "be     2f\n\t"                                                         \
 251         " cmp   %1, 4\n\t"                                                      \
 252         "be     1f\n\t"                                                         \
 253         " srl   %%l1, 24, %%l2\n\t"                                             \
 254         "srl    %%l1, 16, %%g7\n"                                               \
 255 "4:\t"  "stb    %%l2, [%0]\n\t"                                                 \
 256         "srl    %%l1, 8, %%l2\n"                                                \
 257 "5:\t"  "stb    %%g7, [%0 + 1]\n\t"                                             \
 258         "ld     [%2 + 4], %%g7\n"                                               \
 259 "6:\t"  "stb    %%l2, [%0 + 2]\n\t"                                             \
 260         "srl    %%g7, 24, %%l2\n"                                               \
 261 "7:\t"  "stb    %%l1, [%0 + 3]\n\t"                                             \
 262         "srl    %%g7, 16, %%l1\n"                                               \
 263 "8:\t"  "stb    %%l2, [%0 + 4]\n\t"                                             \
 264         "srl    %%g7, 8, %%l2\n"                                                \
 265 "9:\t"  "stb    %%l1, [%0 + 5]\n"                                               \
 266 "10:\t" "stb    %%l2, [%0 + 6]\n\t"                                             \
 267         "b      0f\n"                                                           \
 268 "11:\t" " stb   %%g7, [%0 + 7]\n"                                               \
 269 "1:\t"  "srl    %%l1, 16, %%g7\n"                                               \
 270 "12:\t" "stb    %%l2, [%0]\n\t"                                                 \
 271         "srl    %%l1, 8, %%l2\n"                                                \
 272 "13:\t" "stb    %%g7, [%0 + 1]\n"                                               \
 273 "14:\t" "stb    %%l2, [%0 + 2]\n\t"                                             \
 274         "b      0f\n"                                                           \
 275 "15:\t" " stb   %%l1, [%0 + 3]\n"                                               \
 276 "2:\t"  "srl    %%l1, 8, %%l2\n"                                                \
 277 "16:\t" "stb    %%l2, [%0]\n"                                                   \
 278 "17:\t" "stb    %%l1, [%0 + 1]\n"                                               \
 279 "0:\n\n\t"                                                                      \
 280         ".section __ex_table,#alloc\n\t"                                        \
 281         ".word  4b, " #errh "\n\t"                                              \
 282         ".word  5b, " #errh "\n\t"                                              \
 283         ".word  6b, " #errh "\n\t"                                              \
 284         ".word  7b, " #errh "\n\t"                                              \
 285         ".word  8b, " #errh "\n\t"                                              \
 286         ".word  9b, " #errh "\n\t"                                              \
 287         ".word  10b, " #errh "\n\t"                                             \
 288         ".word  11b, " #errh "\n\t"                                             \
 289         ".word  12b, " #errh "\n\t"                                             \
 290         ".word  13b, " #errh "\n\t"                                             \
 291         ".word  14b, " #errh "\n\t"                                             \
 292         ".word  15b, " #errh "\n\t"                                             \
 293         ".word  16b, " #errh "\n\t"                                             \
 294         ".word  17b, " #errh "\n\n\t"                                           \
 295         ".previous\n\t"                                                         \
 296         : : "r" (dst_addr), "r" (size), "r" (src_val)                           \
 297         : "l1", "l2", "g7", "g1", "cc");                                        \
 298 })
 299
 300 #define do_integer_store(reg_num, size, dst_addr, regs, errh) ({                \
 301         unsigned long *src_val;                                                 \
 302         static unsigned long zero[2] = { 0, };                                  \
 303                                                                                 \
 304         if (reg_num) src_val = fetch_reg_addr(reg_num, regs);                   \
 305         else {                                                                  \
 306                 src_val = &zero[0];                                             \
 307                 if (size == 8)                                                  \
 308                         zero[1] = fetch_reg(1, regs);                           \
 309         }                                                                       \
 310         store_common(dst_addr, size, src_val, errh);                            \
 311 })
 312
 313 /* XXX Need to capture/release other cpu's for SMP around this. */
 314 #define do_atomic(srcdest_reg, mem, errh) ({                                    \
 315         unsigned long flags, tmp;                                               \
 316                                                                                 \
 317         save_and_cli(flags);                                                    \
 318         tmp = *srcdest_reg;                                                     \
 319         do_integer_load(srcdest_reg, 4, mem, 0, errh);                          \
 320         store_common(mem, 4, &tmp, errh);                                       \
 321         restore_flags(flags);                                                   \
 322 })
 323
 324 static inline void advance(struct pt_regs *regs)
 325 {
 326         regs->pc   = regs->npc;
 327         regs->npc += 4;
 328 }
 329
 330 static inline int floating_point_load_or_store_p(unsigned int insn)
 331 {
 332         return (insn >> 24) & 1;
 333 }
 334
 335 static inline int ok_for_kernel(unsigned int insn)
 336 {
 337         return !floating_point_load_or_store_p(insn);
 338 }
 339
 340 void kernel_mna_trap_fault(struct pt_regs *regs, unsigned int insn) __asm__ ("kernel_mna_trap_fault");
 341
 342 void kernel_mna_trap_fault(struct pt_regs *regs, unsigned int insn)
 343 {
 344         unsigned long g2 = regs->u_regs [UREG_G2];
 345         unsigned long fixup = search_exception_table (regs->pc, &g2);
 346
 347         if (!fixup) {
 348                 unsigned long address = compute_effective_address(regs, insn);
 349                 if(address < PAGE_SIZE) {
 350                         printk(KERN_ALERT "Unable to handle kernel NULL pointer dereference in mna handler");
 351                 } else
 352                         printk(KERN_ALERT "Unable to handle kernel paging request in mna handler");
 353                 printk(KERN_ALERT " at virtual address %08lx\n",address);
 354                 printk(KERN_ALERT "current->{mm,active_mm}->context = %08lx\n",
 355                         (current->mm ? current->mm->context :
 356                         current->active_mm->context));
 357                 printk(KERN_ALERT "current->{mm,active_mm}->pgd = %08lx\n",
 358                         (current->mm ? (unsigned long) current->mm->pgd :
 359                         (unsigned long) current->active_mm->pgd));
 360                 die_if_kernel("Oops", regs);
 361                 /* Not reached */
 362         }
 363         regs->pc = fixup;
 364         regs->npc = regs->pc + 4;
 365         regs->u_regs [UREG_G2] = g2;
 366 }
 367
 368 asmlinkage void kernel_unaligned_trap(struct pt_regs *regs, unsigned int insn)
 369 {
 370         enum direction dir = decode_direction(insn);
 371         int size = decode_access_size(insn);
 372
 373         if(!ok_for_kernel(insn) || dir == both) {
 374                 printk("Unsupported unaligned load/store trap for kernel at <%08lx>.\n",
 375                        regs->pc);
 376                 unaligned_panic("Wheee. Kernel does fpu/atomic unaligned load/store.");
 377
 378                 __asm__ __volatile__ ("\n"
 379 "kernel_unaligned_trap_fault:\n\t"
 380                 "mov    %0, %%o0\n\t"
 381                 "call   kernel_mna_trap_fault\n\t"
 382                 " mov   %1, %%o1\n\t"
 383                 :
 384                 : "r" (regs), "r" (insn)
 385                 : "o0", "o1", "o2", "o3", "o4", "o5", "o7",
 386                   "g1", "g2", "g3", "g4", "g5", "g7", "cc");
 387         } else {
 388                 unsigned long addr = compute_effective_address(regs, insn);
 389
 390 #ifdef DEBUG_MNA
 391                 printk("KMNA: pc=%08lx [dir=%s addr=%08lx size=%d] retpc[%08lx]\n",
 392                        regs->pc, dirstrings[dir], addr, size, regs->u_regs[UREG_RETPC]);
 393 #endif
 394                 switch(dir) {
 395                 case load:
 396                         do_integer_load(fetch_reg_addr(((insn>>25)&0x1f), regs),
 397                                         size, (unsigned long *) addr,
 398                                         decode_signedness(insn),
 399                                         kernel_unaligned_trap_fault);
 400                         break;
 401
 402                 case store:
 403                         do_integer_store(((insn>>25)&0x1f), size,
 404                                          (unsigned long *) addr, regs,
 405                                          kernel_unaligned_trap_fault);
 406                         break;
 407 #if 0 /* unsupported */
 408                 case both:
 409                         do_atomic(fetch_reg_addr(((insn>>25)&0x1f), regs),
 410                                   (unsigned long *) addr,
 411                                   kernel_unaligned_trap_fault);
 412                         break;
 413 #endif
 414                 default:
 415                         panic("Impossible kernel unaligned trap.");
 416                         /* Not reached... */
 417                 }
 418                 advance(regs);
 419         }
 420 }
 421
 422 static inline int ok_for_user(struct pt_regs *regs, unsigned int insn,
 423                               enum direction dir)
 424 {
 425         unsigned int reg;
 426         int retval, check = (dir == load) ? VERIFY_READ : VERIFY_WRITE;
 427         int size = ((insn >> 19) & 3) == 3 ? 8 : 4;
 428
 429         if((regs->pc | regs->npc) & 3)
 430                 return 0;
 431
 432         /* Must verify_area() in all the necessary places. */
 433 #define WINREG_ADDR(regnum) ((void *)(((unsigned long *)regs->u_regs[UREG_FP])+(regnum)))
 434         retval = 0;
 435         reg = (insn >> 25) & 0x1f;
 436         if(reg >= 16) {
 437                 retval = verify_area(check, WINREG_ADDR(reg - 16), size);
 438                 if(retval)
 439                         return retval;
 440         }
 441         reg = (insn >> 14) & 0x1f;
 442         if(reg >= 16) {
 443                 retval = verify_area(check, WINREG_ADDR(reg - 16), size);
 444                 if(retval)
 445                         return retval;
 446         }
 447         if(!(insn & 0x2000)) {
 448                 reg = (insn & 0x1f);
 449                 if(reg >= 16) {
 450                         retval = verify_area(check, WINREG_ADDR(reg - 16), size);
 451                         if(retval)
 452                                 return retval;
 453                 }
 454         }
 455         return retval;
 456 #undef WINREG_ADDR
 457 }
 458
 459 void user_mna_trap_fault(struct pt_regs *regs, unsigned int insn) __asm__ ("user_mna_trap_fault");
 460
 461 void user_mna_trap_fault(struct pt_regs *regs, unsigned int insn)
 462 {
 463         siginfo_t info;
 464
 465         info.si_signo = SIGBUS;
 466         info.si_errno = 0;
 467         info.si_code = BUS_ADRALN;
 468         info.si_addr = (void *)safe_compute_effective_address(regs, insn);
 469         info.si_trapno = 0;
 470         send_sig_info(SIGBUS, &info, current);
 471 }
 472
 473 asmlinkage void user_unaligned_trap(struct pt_regs *regs, unsigned int insn)
 474 {
 475         enum direction dir;
 476
 477         lock_kernel();
 478         if(!(current->thread.flags & SPARC_FLAG_UNALIGNED) ||
 479            (((insn >> 30) & 3) != 3))
 480                 goto kill_user;
 481         dir = decode_direction(insn);
 482         if(!ok_for_user(regs, insn, dir)) {
 483                 goto kill_user;
 484         } else {
 485                 int size = decode_access_size(insn);
 486                 unsigned long addr;
 487
 488                 if(floating_point_load_or_store_p(insn)) {
 489                         printk("User FPU load/store unaligned unsupported.\n");
 490                         goto kill_user;
 491                 }
 492
 493                 addr = compute_effective_address(regs, insn);
 494                 switch(dir) {
 495                 case load:
 496                         do_integer_load(fetch_reg_addr(((insn>>25)&0x1f), regs),
 497                                         size, (unsigned long *) addr,
 498                                         decode_signedness(insn),
 499                                         user_unaligned_trap_fault);
 500                         break;
 501
 502                 case store:
 503                         do_integer_store(((insn>>25)&0x1f), size,
 504                                          (unsigned long *) addr, regs,
 505                                          user_unaligned_trap_fault);
 506                         break;
 507
 508                 case both:
 509                         do_atomic(fetch_reg_addr(((insn>>25)&0x1f), regs),
 510                                   (unsigned long *) addr,
 511                                   user_unaligned_trap_fault);
 512                         break;
 513
 514                 default:
 515                         unaligned_panic("Impossible user unaligned trap.");
 516
 517                         __asm__ __volatile__ ("\n"
 518 "user_unaligned_trap_fault:\n\t"
 519                         "mov    %0, %%o0\n\t"
 520                         "call   user_mna_trap_fault\n\t"
 521                         " mov   %1, %%o1\n\t"
 522                         :
 523                         : "r" (regs), "r" (insn)
 524                         : "o0", "o1", "o2", "o3", "o4", "o5", "o7",
 525                           "g1", "g2", "g3", "g4", "g5", "g7", "cc");
 526                         goto out;
 527                 }
 528                 advance(regs);
 529                 goto out;
 530         }
 531
 532 kill_user:
 533         user_mna_trap_fault(regs, insn);
 534 out:
 535         unlock_kernel();
 536 }