1/* 2 * This file is subject to the terms and conditions of the GNU General Public 3 * License. See the file "COPYING" in the main directory of this archive 4 * for more details. 5 * 6 * Unified implementation of memcpy, memmove and the __copy_user backend. 7 * 8 * Copyright (C) 1998, 99, 2000, 01, 2002 Ralf Baechle (ralf@gnu.org) 9 * Copyright (C) 1999, 2000, 01, 2002 Silicon Graphics, Inc. 10 * Copyright (C) 2002 Broadcom, Inc. 11 * memcpy/copy_user author: Mark Vandevoorde 12 * 13 * Mnemonic names for arguments to memcpy/__copy_user 14 */ 15 16#include <linux/export.h> 17#include <asm/asm.h> 18#include <asm/asm-offsets.h> 19#include <asm/regdef.h> 20 21#define dst a0 22#define src a1 23#define len a2 24 25/* 26 * Spec 27 * 28 * memcpy copies len bytes from src to dst and sets v0 to dst. 29 * It assumes that 30 * - src and dst don't overlap 31 * - src is readable 32 * - dst is writable 33 * memcpy uses the standard calling convention 34 * 35 * __copy_user copies up to len bytes from src to dst and sets a2 (len) to 36 * the number of uncopied bytes due to an exception caused by a read or write. 37 * __copy_user assumes that src and dst don't overlap, and that the call is 38 * implementing one of the following: 39 * copy_to_user 40 * - src is readable (no exceptions when reading src) 41 * copy_from_user 42 * - dst is writable (no exceptions when writing dst) 43 * __copy_user uses a non-standard calling convention; see 44 * arch/mips/include/asm/uaccess.h 45 * 46 * When an exception happens on a load, the handler must 47 # ensure that all of the destination buffer is overwritten to prevent 48 * leaking information to user mode programs. 49 */ 50 51/* 52 * Implementation 53 */ 54 55/* 56 * The exception handler for loads requires that: 57 * 1- AT contain the address of the byte just past the end of the source 58 * of the copy, 59 * 2- src_entry <= src < AT, and 60 * 3- (dst - src) == (dst_entry - src_entry), 61 * The _entry suffix denotes values when __copy_user was called. 62 * 63 * (1) is set up up by uaccess.h and maintained by not writing AT in copy_user 64 * (2) is met by incrementing src by the number of bytes copied 65 * (3) is met by not doing loads between a pair of increments of dst and src 66 * 67 * The exception handlers for stores adjust len (if necessary) and return. 68 * These handlers do not need to overwrite any data. 69 * 70 * For __rmemcpy and memmove an exception is always a kernel bug, therefore 71 * they're not protected. 72 */ 73 74#define EXC(inst_reg,addr,handler) \ 759: inst_reg, addr; \ 76 .section __ex_table,"a"; \ 77 PTR_WD 9b, handler; \ 78 .previous 79 80/* 81 * Only on the 64-bit kernel we can made use of 64-bit registers. 82 */ 83 84#define LOAD ld 85#define LOADL ldl 86#define LOADR ldr 87#define STOREL sdl 88#define STORER sdr 89#define STORE sd 90#define ADD daddu 91#define SUB dsubu 92#define SRL dsrl 93#define SRA dsra 94#define SLL dsll 95#define SLLV dsllv 96#define SRLV dsrlv 97#define NBYTES 8 98#define LOG_NBYTES 3 99 100/* 101 * As we are sharing code base with the mips32 tree (which use the o32 ABI 102 * register definitions). We need to redefine the register definitions from 103 * the n64 ABI register naming to the o32 ABI register naming. 104 */ 105#undef t0 106#undef t1 107#undef t2 108#undef t3 109#define t0 $8 110#define t1 $9 111#define t2 $10 112#define t3 $11 113#define t4 $12 114#define t5 $13 115#define t6 $14 116#define t7 $15 117 118#ifdef CONFIG_CPU_LITTLE_ENDIAN 119#define LDFIRST LOADR 120#define LDREST LOADL 121#define STFIRST STORER 122#define STREST STOREL 123#define SHIFT_DISCARD SLLV 124#else 125#define LDFIRST LOADL 126#define LDREST LOADR 127#define STFIRST STOREL 128#define STREST STORER 129#define SHIFT_DISCARD SRLV 130#endif 131 132#define FIRST(unit) ((unit)*NBYTES) 133#define REST(unit) (FIRST(unit)+NBYTES-1) 134#define UNIT(unit) FIRST(unit) 135 136#define ADDRMASK (NBYTES-1) 137 138 .text 139 .set noreorder 140 .set noat 141 142/* 143 * A combined memcpy/__copy_user 144 * __copy_user sets len to 0 for success; else to an upper bound of 145 * the number of uncopied bytes. 146 * memcpy sets v0 to dst. 147 */ 148 .align 5 149LEAF(memcpy) /* a0=dst a1=src a2=len */ 150EXPORT_SYMBOL(memcpy) 151 move v0, dst /* return value */ 152__memcpy: 153FEXPORT(__raw_copy_from_user) 154EXPORT_SYMBOL(__raw_copy_from_user) 155FEXPORT(__raw_copy_to_user) 156EXPORT_SYMBOL(__raw_copy_to_user) 157 /* 158 * Note: dst & src may be unaligned, len may be 0 159 * Temps 160 */ 161 # 162 # Octeon doesn't care if the destination is unaligned. The hardware 163 # can fix it faster than we can special case the assembly. 164 # 165 pref 0, 0(src) 166 sltu t0, len, NBYTES # Check if < 1 word 167 bnez t0, copy_bytes_checklen 168 and t0, src, ADDRMASK # Check if src unaligned 169 bnez t0, src_unaligned 170 sltu t0, len, 4*NBYTES # Check if < 4 words 171 bnez t0, less_than_4units 172 sltu t0, len, 8*NBYTES # Check if < 8 words 173 bnez t0, less_than_8units 174 sltu t0, len, 16*NBYTES # Check if < 16 words 175 bnez t0, cleanup_both_aligned 176 sltu t0, len, 128+1 # Check if len < 129 177 bnez t0, 1f # Skip prefetch if len is too short 178 sltu t0, len, 256+1 # Check if len < 257 179 bnez t0, 1f # Skip prefetch if len is too short 180 pref 0, 128(src) # We must not prefetch invalid addresses 181 # 182 # This is where we loop if there is more than 128 bytes left 1832: pref 0, 256(src) # We must not prefetch invalid addresses 184 # 185 # This is where we loop if we can't prefetch anymore 1861: 187EXC( LOAD t0, UNIT(0)(src), l_exc) 188EXC( LOAD t1, UNIT(1)(src), l_exc_copy) 189EXC( LOAD t2, UNIT(2)(src), l_exc_copy) 190EXC( LOAD t3, UNIT(3)(src), l_exc_copy) 191 SUB len, len, 16*NBYTES 192EXC( STORE t0, UNIT(0)(dst), s_exc_p16u) 193EXC( STORE t1, UNIT(1)(dst), s_exc_p15u) 194EXC( STORE t2, UNIT(2)(dst), s_exc_p14u) 195EXC( STORE t3, UNIT(3)(dst), s_exc_p13u) 196EXC( LOAD t0, UNIT(4)(src), l_exc_copy) 197EXC( LOAD t1, UNIT(5)(src), l_exc_copy) 198EXC( LOAD t2, UNIT(6)(src), l_exc_copy) 199EXC( LOAD t3, UNIT(7)(src), l_exc_copy) 200EXC( STORE t0, UNIT(4)(dst), s_exc_p12u) 201EXC( STORE t1, UNIT(5)(dst), s_exc_p11u) 202EXC( STORE t2, UNIT(6)(dst), s_exc_p10u) 203 ADD src, src, 16*NBYTES 204EXC( STORE t3, UNIT(7)(dst), s_exc_p9u) 205 ADD dst, dst, 16*NBYTES 206EXC( LOAD t0, UNIT(-8)(src), l_exc_copy_rewind16) 207EXC( LOAD t1, UNIT(-7)(src), l_exc_copy_rewind16) 208EXC( LOAD t2, UNIT(-6)(src), l_exc_copy_rewind16) 209EXC( LOAD t3, UNIT(-5)(src), l_exc_copy_rewind16) 210EXC( STORE t0, UNIT(-8)(dst), s_exc_p8u) 211EXC( STORE t1, UNIT(-7)(dst), s_exc_p7u) 212EXC( STORE t2, UNIT(-6)(dst), s_exc_p6u) 213EXC( STORE t3, UNIT(-5)(dst), s_exc_p5u) 214EXC( LOAD t0, UNIT(-4)(src), l_exc_copy_rewind16) 215EXC( LOAD t1, UNIT(-3)(src), l_exc_copy_rewind16) 216EXC( LOAD t2, UNIT(-2)(src), l_exc_copy_rewind16) 217EXC( LOAD t3, UNIT(-1)(src), l_exc_copy_rewind16) 218EXC( STORE t0, UNIT(-4)(dst), s_exc_p4u) 219EXC( STORE t1, UNIT(-3)(dst), s_exc_p3u) 220EXC( STORE t2, UNIT(-2)(dst), s_exc_p2u) 221EXC( STORE t3, UNIT(-1)(dst), s_exc_p1u) 222 sltu t0, len, 256+1 # See if we can prefetch more 223 beqz t0, 2b 224 sltu t0, len, 128 # See if we can loop more time 225 beqz t0, 1b 226 nop 227 # 228 # Jump here if there are less than 16*NBYTES left. 229 # 230cleanup_both_aligned: 231 beqz len, done 232 sltu t0, len, 8*NBYTES 233 bnez t0, less_than_8units 234 nop 235EXC( LOAD t0, UNIT(0)(src), l_exc) 236EXC( LOAD t1, UNIT(1)(src), l_exc_copy) 237EXC( LOAD t2, UNIT(2)(src), l_exc_copy) 238EXC( LOAD t3, UNIT(3)(src), l_exc_copy) 239 SUB len, len, 8*NBYTES 240EXC( STORE t0, UNIT(0)(dst), s_exc_p8u) 241EXC( STORE t1, UNIT(1)(dst), s_exc_p7u) 242EXC( STORE t2, UNIT(2)(dst), s_exc_p6u) 243EXC( STORE t3, UNIT(3)(dst), s_exc_p5u) 244EXC( LOAD t0, UNIT(4)(src), l_exc_copy) 245EXC( LOAD t1, UNIT(5)(src), l_exc_copy) 246EXC( LOAD t2, UNIT(6)(src), l_exc_copy) 247EXC( LOAD t3, UNIT(7)(src), l_exc_copy) 248EXC( STORE t0, UNIT(4)(dst), s_exc_p4u) 249EXC( STORE t1, UNIT(5)(dst), s_exc_p3u) 250EXC( STORE t2, UNIT(6)(dst), s_exc_p2u) 251EXC( STORE t3, UNIT(7)(dst), s_exc_p1u) 252 ADD src, src, 8*NBYTES 253 beqz len, done 254 ADD dst, dst, 8*NBYTES 255 # 256 # Jump here if there are less than 8*NBYTES left. 257 # 258less_than_8units: 259 sltu t0, len, 4*NBYTES 260 bnez t0, less_than_4units 261 nop 262EXC( LOAD t0, UNIT(0)(src), l_exc) 263EXC( LOAD t1, UNIT(1)(src), l_exc_copy) 264EXC( LOAD t2, UNIT(2)(src), l_exc_copy) 265EXC( LOAD t3, UNIT(3)(src), l_exc_copy) 266 SUB len, len, 4*NBYTES 267EXC( STORE t0, UNIT(0)(dst), s_exc_p4u) 268EXC( STORE t1, UNIT(1)(dst), s_exc_p3u) 269EXC( STORE t2, UNIT(2)(dst), s_exc_p2u) 270EXC( STORE t3, UNIT(3)(dst), s_exc_p1u) 271 ADD src, src, 4*NBYTES 272 beqz len, done 273 ADD dst, dst, 4*NBYTES 274 # 275 # Jump here if there are less than 4*NBYTES left. This means 276 # we may need to copy up to 3 NBYTES words. 277 # 278less_than_4units: 279 sltu t0, len, 1*NBYTES 280 bnez t0, copy_bytes_checklen 281 nop 282 # 283 # 1) Copy NBYTES, then check length again 284 # 285EXC( LOAD t0, 0(src), l_exc) 286 SUB len, len, NBYTES 287 sltu t1, len, 8 288EXC( STORE t0, 0(dst), s_exc_p1u) 289 ADD src, src, NBYTES 290 bnez t1, copy_bytes_checklen 291 ADD dst, dst, NBYTES 292 # 293 # 2) Copy NBYTES, then check length again 294 # 295EXC( LOAD t0, 0(src), l_exc) 296 SUB len, len, NBYTES 297 sltu t1, len, 8 298EXC( STORE t0, 0(dst), s_exc_p1u) 299 ADD src, src, NBYTES 300 bnez t1, copy_bytes_checklen 301 ADD dst, dst, NBYTES 302 # 303 # 3) Copy NBYTES, then check length again 304 # 305EXC( LOAD t0, 0(src), l_exc) 306 SUB len, len, NBYTES 307 ADD src, src, NBYTES 308 ADD dst, dst, NBYTES 309 b copy_bytes_checklen 310EXC( STORE t0, -8(dst), s_exc_p1u) 311 312src_unaligned: 313#define rem t8 314 SRL t0, len, LOG_NBYTES+2 # +2 for 4 units/iter 315 beqz t0, cleanup_src_unaligned 316 and rem, len, (4*NBYTES-1) # rem = len % 4*NBYTES 3171: 318/* 319 * Avoid consecutive LD*'s to the same register since some mips 320 * implementations can't issue them in the same cycle. 321 * It's OK to load FIRST(N+1) before REST(N) because the two addresses 322 * are to the same unit (unless src is aligned, but it's not). 323 */ 324EXC( LDFIRST t0, FIRST(0)(src), l_exc) 325EXC( LDFIRST t1, FIRST(1)(src), l_exc_copy) 326 SUB len, len, 4*NBYTES 327EXC( LDREST t0, REST(0)(src), l_exc_copy) 328EXC( LDREST t1, REST(1)(src), l_exc_copy) 329EXC( LDFIRST t2, FIRST(2)(src), l_exc_copy) 330EXC( LDFIRST t3, FIRST(3)(src), l_exc_copy) 331EXC( LDREST t2, REST(2)(src), l_exc_copy) 332EXC( LDREST t3, REST(3)(src), l_exc_copy) 333 ADD src, src, 4*NBYTES 334EXC( STORE t0, UNIT(0)(dst), s_exc_p4u) 335EXC( STORE t1, UNIT(1)(dst), s_exc_p3u) 336EXC( STORE t2, UNIT(2)(dst), s_exc_p2u) 337EXC( STORE t3, UNIT(3)(dst), s_exc_p1u) 338 bne len, rem, 1b 339 ADD dst, dst, 4*NBYTES 340 341cleanup_src_unaligned: 342 beqz len, done 343 and rem, len, NBYTES-1 # rem = len % NBYTES 344 beq rem, len, copy_bytes 345 nop 3461: 347EXC( LDFIRST t0, FIRST(0)(src), l_exc) 348EXC( LDREST t0, REST(0)(src), l_exc_copy) 349 SUB len, len, NBYTES 350EXC( STORE t0, 0(dst), s_exc_p1u) 351 ADD src, src, NBYTES 352 bne len, rem, 1b 353 ADD dst, dst, NBYTES 354 355copy_bytes_checklen: 356 beqz len, done 357 nop 358copy_bytes: 359 /* 0 < len < NBYTES */ 360#define COPY_BYTE(N) \ 361EXC( lb t0, N(src), l_exc); \ 362 SUB len, len, 1; \ 363 beqz len, done; \ 364EXC( sb t0, N(dst), s_exc_p1) 365 366 COPY_BYTE(0) 367 COPY_BYTE(1) 368 COPY_BYTE(2) 369 COPY_BYTE(3) 370 COPY_BYTE(4) 371 COPY_BYTE(5) 372EXC( lb t0, NBYTES-2(src), l_exc) 373 SUB len, len, 1 374 jr ra 375EXC( sb t0, NBYTES-2(dst), s_exc_p1) 376done: 377 jr ra 378 nop 379 END(memcpy) 380 381l_exc_copy_rewind16: 382 /* Rewind src and dst by 16*NBYTES for l_exc_copy */ 383 SUB src, src, 16*NBYTES 384 SUB dst, dst, 16*NBYTES 385l_exc_copy: 386 /* 387 * Copy bytes from src until faulting load address (or until a 388 * lb faults) 389 * 390 * When reached by a faulting LDFIRST/LDREST, THREAD_BUADDR($28) 391 * may be more than a byte beyond the last address. 392 * Hence, the lb below may get an exception. 393 * 394 * Assumes src < THREAD_BUADDR($28) 395 */ 396 LOAD t0, TI_TASK($28) 397 LOAD t0, THREAD_BUADDR(t0) 3981: 399EXC( lb t1, 0(src), l_exc) 400 ADD src, src, 1 401 sb t1, 0(dst) # can't fault -- we're copy_from_user 402 bne src, t0, 1b 403 ADD dst, dst, 1 404l_exc: 405 LOAD t0, TI_TASK($28) 406 LOAD t0, THREAD_BUADDR(t0) # t0 is just past last good address 407 SUB len, AT, t0 # len number of uncopied bytes 408 jr ra 409 nop 410 411 412#define SEXC(n) \ 413s_exc_p ## n ## u: \ 414 jr ra; \ 415 ADD len, len, n*NBYTES 416 417SEXC(16) 418SEXC(15) 419SEXC(14) 420SEXC(13) 421SEXC(12) 422SEXC(11) 423SEXC(10) 424SEXC(9) 425SEXC(8) 426SEXC(7) 427SEXC(6) 428SEXC(5) 429SEXC(4) 430SEXC(3) 431SEXC(2) 432SEXC(1) 433 434s_exc_p1: 435 jr ra 436 ADD len, len, 1 437s_exc: 438 jr ra 439 nop 440 441 .align 5 442LEAF(memmove) 443EXPORT_SYMBOL(memmove) 444 ADD t0, a0, a2 445 ADD t1, a1, a2 446 sltu t0, a1, t0 # dst + len <= src -> memcpy 447 sltu t1, a0, t1 # dst >= src + len -> memcpy 448 and t0, t1 449 beqz t0, __memcpy 450 move v0, a0 /* return value */ 451 beqz a2, r_out 452 END(memmove) 453 454 /* fall through to __rmemcpy */ 455LEAF(__rmemcpy) /* a0=dst a1=src a2=len */ 456 sltu t0, a1, a0 457 beqz t0, r_end_bytes_up # src >= dst 458 nop 459 ADD a0, a2 # dst = dst + len 460 ADD a1, a2 # src = src + len 461 462r_end_bytes: 463 lb t0, -1(a1) 464 SUB a2, a2, 0x1 465 sb t0, -1(a0) 466 SUB a1, a1, 0x1 467 bnez a2, r_end_bytes 468 SUB a0, a0, 0x1 469 470r_out: 471 jr ra 472 move a2, zero 473 474r_end_bytes_up: 475 lb t0, (a1) 476 SUB a2, a2, 0x1 477 sb t0, (a0) 478 ADD a1, a1, 0x1 479 bnez a2, r_end_bytes_up 480 ADD a0, a0, 0x1 481 482 jr ra 483 move a2, zero 484 END(__rmemcpy) 485