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 <asm/asm.h> 17#include <asm/asm-offsets.h> 18#include <asm/export.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 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) 157FEXPORT(__raw_copy_in_user) 158EXPORT_SYMBOL(__raw_copy_in_user) 159 /* 160 * Note: dst & src may be unaligned, len may be 0 161 * Temps 162 */ 163 # 164 # Octeon doesn't care if the destination is unaligned. The hardware 165 # can fix it faster than we can special case the assembly. 166 # 167 pref 0, 0(src) 168 sltu t0, len, NBYTES # Check if < 1 word 169 bnez t0, copy_bytes_checklen 170 and t0, src, ADDRMASK # Check if src unaligned 171 bnez t0, src_unaligned 172 sltu t0, len, 4*NBYTES # Check if < 4 words 173 bnez t0, less_than_4units 174 sltu t0, len, 8*NBYTES # Check if < 8 words 175 bnez t0, less_than_8units 176 sltu t0, len, 16*NBYTES # Check if < 16 words 177 bnez t0, cleanup_both_aligned 178 sltu t0, len, 128+1 # Check if len < 129 179 bnez t0, 1f # Skip prefetch if len is too short 180 sltu t0, len, 256+1 # Check if len < 257 181 bnez t0, 1f # Skip prefetch if len is too short 182 pref 0, 128(src) # We must not prefetch invalid addresses 183 # 184 # This is where we loop if there is more than 128 bytes left 1852: pref 0, 256(src) # We must not prefetch invalid addresses 186 # 187 # This is where we loop if we can't prefetch anymore 1881: 189EXC( LOAD t0, UNIT(0)(src), l_exc) 190EXC( LOAD t1, UNIT(1)(src), l_exc_copy) 191EXC( LOAD t2, UNIT(2)(src), l_exc_copy) 192EXC( LOAD t3, UNIT(3)(src), l_exc_copy) 193 SUB len, len, 16*NBYTES 194EXC( STORE t0, UNIT(0)(dst), s_exc_p16u) 195EXC( STORE t1, UNIT(1)(dst), s_exc_p15u) 196EXC( STORE t2, UNIT(2)(dst), s_exc_p14u) 197EXC( STORE t3, UNIT(3)(dst), s_exc_p13u) 198EXC( LOAD t0, UNIT(4)(src), l_exc_copy) 199EXC( LOAD t1, UNIT(5)(src), l_exc_copy) 200EXC( LOAD t2, UNIT(6)(src), l_exc_copy) 201EXC( LOAD t3, UNIT(7)(src), l_exc_copy) 202EXC( STORE t0, UNIT(4)(dst), s_exc_p12u) 203EXC( STORE t1, UNIT(5)(dst), s_exc_p11u) 204EXC( STORE t2, UNIT(6)(dst), s_exc_p10u) 205 ADD src, src, 16*NBYTES 206EXC( STORE t3, UNIT(7)(dst), s_exc_p9u) 207 ADD dst, dst, 16*NBYTES 208EXC( LOAD t0, UNIT(-8)(src), l_exc_copy_rewind16) 209EXC( LOAD t1, UNIT(-7)(src), l_exc_copy_rewind16) 210EXC( LOAD t2, UNIT(-6)(src), l_exc_copy_rewind16) 211EXC( LOAD t3, UNIT(-5)(src), l_exc_copy_rewind16) 212EXC( STORE t0, UNIT(-8)(dst), s_exc_p8u) 213EXC( STORE t1, UNIT(-7)(dst), s_exc_p7u) 214EXC( STORE t2, UNIT(-6)(dst), s_exc_p6u) 215EXC( STORE t3, UNIT(-5)(dst), s_exc_p5u) 216EXC( LOAD t0, UNIT(-4)(src), l_exc_copy_rewind16) 217EXC( LOAD t1, UNIT(-3)(src), l_exc_copy_rewind16) 218EXC( LOAD t2, UNIT(-2)(src), l_exc_copy_rewind16) 219EXC( LOAD t3, UNIT(-1)(src), l_exc_copy_rewind16) 220EXC( STORE t0, UNIT(-4)(dst), s_exc_p4u) 221EXC( STORE t1, UNIT(-3)(dst), s_exc_p3u) 222EXC( STORE t2, UNIT(-2)(dst), s_exc_p2u) 223EXC( STORE t3, UNIT(-1)(dst), s_exc_p1u) 224 sltu t0, len, 256+1 # See if we can prefetch more 225 beqz t0, 2b 226 sltu t0, len, 128 # See if we can loop more time 227 beqz t0, 1b 228 nop 229 # 230 # Jump here if there are less than 16*NBYTES left. 231 # 232cleanup_both_aligned: 233 beqz len, done 234 sltu t0, len, 8*NBYTES 235 bnez t0, less_than_8units 236 nop 237EXC( LOAD t0, UNIT(0)(src), l_exc) 238EXC( LOAD t1, UNIT(1)(src), l_exc_copy) 239EXC( LOAD t2, UNIT(2)(src), l_exc_copy) 240EXC( LOAD t3, UNIT(3)(src), l_exc_copy) 241 SUB len, len, 8*NBYTES 242EXC( STORE t0, UNIT(0)(dst), s_exc_p8u) 243EXC( STORE t1, UNIT(1)(dst), s_exc_p7u) 244EXC( STORE t2, UNIT(2)(dst), s_exc_p6u) 245EXC( STORE t3, UNIT(3)(dst), s_exc_p5u) 246EXC( LOAD t0, UNIT(4)(src), l_exc_copy) 247EXC( LOAD t1, UNIT(5)(src), l_exc_copy) 248EXC( LOAD t2, UNIT(6)(src), l_exc_copy) 249EXC( LOAD t3, UNIT(7)(src), l_exc_copy) 250EXC( STORE t0, UNIT(4)(dst), s_exc_p4u) 251EXC( STORE t1, UNIT(5)(dst), s_exc_p3u) 252EXC( STORE t2, UNIT(6)(dst), s_exc_p2u) 253EXC( STORE t3, UNIT(7)(dst), s_exc_p1u) 254 ADD src, src, 8*NBYTES 255 beqz len, done 256 ADD dst, dst, 8*NBYTES 257 # 258 # Jump here if there are less than 8*NBYTES left. 259 # 260less_than_8units: 261 sltu t0, len, 4*NBYTES 262 bnez t0, less_than_4units 263 nop 264EXC( LOAD t0, UNIT(0)(src), l_exc) 265EXC( LOAD t1, UNIT(1)(src), l_exc_copy) 266EXC( LOAD t2, UNIT(2)(src), l_exc_copy) 267EXC( LOAD t3, UNIT(3)(src), l_exc_copy) 268 SUB len, len, 4*NBYTES 269EXC( STORE t0, UNIT(0)(dst), s_exc_p4u) 270EXC( STORE t1, UNIT(1)(dst), s_exc_p3u) 271EXC( STORE t2, UNIT(2)(dst), s_exc_p2u) 272EXC( STORE t3, UNIT(3)(dst), s_exc_p1u) 273 ADD src, src, 4*NBYTES 274 beqz len, done 275 ADD dst, dst, 4*NBYTES 276 # 277 # Jump here if there are less than 4*NBYTES left. This means 278 # we may need to copy up to 3 NBYTES words. 279 # 280less_than_4units: 281 sltu t0, len, 1*NBYTES 282 bnez t0, copy_bytes_checklen 283 nop 284 # 285 # 1) Copy NBYTES, then check length again 286 # 287EXC( LOAD t0, 0(src), l_exc) 288 SUB len, len, NBYTES 289 sltu t1, len, 8 290EXC( STORE t0, 0(dst), s_exc_p1u) 291 ADD src, src, NBYTES 292 bnez t1, copy_bytes_checklen 293 ADD dst, dst, NBYTES 294 # 295 # 2) Copy NBYTES, then check length again 296 # 297EXC( LOAD t0, 0(src), l_exc) 298 SUB len, len, NBYTES 299 sltu t1, len, 8 300EXC( STORE t0, 0(dst), s_exc_p1u) 301 ADD src, src, NBYTES 302 bnez t1, copy_bytes_checklen 303 ADD dst, dst, NBYTES 304 # 305 # 3) Copy NBYTES, then check length again 306 # 307EXC( LOAD t0, 0(src), l_exc) 308 SUB len, len, NBYTES 309 ADD src, src, NBYTES 310 ADD dst, dst, NBYTES 311 b copy_bytes_checklen 312EXC( STORE t0, -8(dst), s_exc_p1u) 313 314src_unaligned: 315#define rem t8 316 SRL t0, len, LOG_NBYTES+2 # +2 for 4 units/iter 317 beqz t0, cleanup_src_unaligned 318 and rem, len, (4*NBYTES-1) # rem = len % 4*NBYTES 3191: 320/* 321 * Avoid consecutive LD*'s to the same register since some mips 322 * implementations can't issue them in the same cycle. 323 * It's OK to load FIRST(N+1) before REST(N) because the two addresses 324 * are to the same unit (unless src is aligned, but it's not). 325 */ 326EXC( LDFIRST t0, FIRST(0)(src), l_exc) 327EXC( LDFIRST t1, FIRST(1)(src), l_exc_copy) 328 SUB len, len, 4*NBYTES 329EXC( LDREST t0, REST(0)(src), l_exc_copy) 330EXC( LDREST t1, REST(1)(src), l_exc_copy) 331EXC( LDFIRST t2, FIRST(2)(src), l_exc_copy) 332EXC( LDFIRST t3, FIRST(3)(src), l_exc_copy) 333EXC( LDREST t2, REST(2)(src), l_exc_copy) 334EXC( LDREST t3, REST(3)(src), l_exc_copy) 335 ADD src, src, 4*NBYTES 336EXC( STORE t0, UNIT(0)(dst), s_exc_p4u) 337EXC( STORE t1, UNIT(1)(dst), s_exc_p3u) 338EXC( STORE t2, UNIT(2)(dst), s_exc_p2u) 339EXC( STORE t3, UNIT(3)(dst), s_exc_p1u) 340 bne len, rem, 1b 341 ADD dst, dst, 4*NBYTES 342 343cleanup_src_unaligned: 344 beqz len, done 345 and rem, len, NBYTES-1 # rem = len % NBYTES 346 beq rem, len, copy_bytes 347 nop 3481: 349EXC( LDFIRST t0, FIRST(0)(src), l_exc) 350EXC( LDREST t0, REST(0)(src), l_exc_copy) 351 SUB len, len, NBYTES 352EXC( STORE t0, 0(dst), s_exc_p1u) 353 ADD src, src, NBYTES 354 bne len, rem, 1b 355 ADD dst, dst, NBYTES 356 357copy_bytes_checklen: 358 beqz len, done 359 nop 360copy_bytes: 361 /* 0 < len < NBYTES */ 362#define COPY_BYTE(N) \ 363EXC( lb t0, N(src), l_exc); \ 364 SUB len, len, 1; \ 365 beqz len, done; \ 366EXC( sb t0, N(dst), s_exc_p1) 367 368 COPY_BYTE(0) 369 COPY_BYTE(1) 370 COPY_BYTE(2) 371 COPY_BYTE(3) 372 COPY_BYTE(4) 373 COPY_BYTE(5) 374EXC( lb t0, NBYTES-2(src), l_exc) 375 SUB len, len, 1 376 jr ra 377EXC( sb t0, NBYTES-2(dst), s_exc_p1) 378done: 379 jr ra 380 nop 381 END(memcpy) 382 383l_exc_copy_rewind16: 384 /* Rewind src and dst by 16*NBYTES for l_exc_copy */ 385 SUB src, src, 16*NBYTES 386 SUB dst, dst, 16*NBYTES 387l_exc_copy: 388 /* 389 * Copy bytes from src until faulting load address (or until a 390 * lb faults) 391 * 392 * When reached by a faulting LDFIRST/LDREST, THREAD_BUADDR($28) 393 * may be more than a byte beyond the last address. 394 * Hence, the lb below may get an exception. 395 * 396 * Assumes src < THREAD_BUADDR($28) 397 */ 398 LOAD t0, TI_TASK($28) 399 LOAD t0, THREAD_BUADDR(t0) 4001: 401EXC( lb t1, 0(src), l_exc) 402 ADD src, src, 1 403 sb t1, 0(dst) # can't fault -- we're copy_from_user 404 bne src, t0, 1b 405 ADD dst, dst, 1 406l_exc: 407 LOAD t0, TI_TASK($28) 408 LOAD t0, THREAD_BUADDR(t0) # t0 is just past last good address 409 SUB len, AT, t0 # len number of uncopied bytes 410 jr ra 411 nop 412 413 414#define SEXC(n) \ 415s_exc_p ## n ## u: \ 416 jr ra; \ 417 ADD len, len, n*NBYTES 418 419SEXC(16) 420SEXC(15) 421SEXC(14) 422SEXC(13) 423SEXC(12) 424SEXC(11) 425SEXC(10) 426SEXC(9) 427SEXC(8) 428SEXC(7) 429SEXC(6) 430SEXC(5) 431SEXC(4) 432SEXC(3) 433SEXC(2) 434SEXC(1) 435 436s_exc_p1: 437 jr ra 438 ADD len, len, 1 439s_exc: 440 jr ra 441 nop 442 443 .align 5 444LEAF(memmove) 445EXPORT_SYMBOL(memmove) 446 ADD t0, a0, a2 447 ADD t1, a1, a2 448 sltu t0, a1, t0 # dst + len <= src -> memcpy 449 sltu t1, a0, t1 # dst >= src + len -> memcpy 450 and t0, t1 451 beqz t0, __memcpy 452 move v0, a0 /* return value */ 453 beqz a2, r_out 454 END(memmove) 455 456 /* fall through to __rmemcpy */ 457LEAF(__rmemcpy) /* a0=dst a1=src a2=len */ 458 sltu t0, a1, a0 459 beqz t0, r_end_bytes_up # src >= dst 460 nop 461 ADD a0, a2 # dst = dst + len 462 ADD a1, a2 # src = src + len 463 464r_end_bytes: 465 lb t0, -1(a1) 466 SUB a2, a2, 0x1 467 sb t0, -1(a0) 468 SUB a1, a1, 0x1 469 bnez a2, r_end_bytes 470 SUB a0, a0, 0x1 471 472r_out: 473 jr ra 474 move a2, zero 475 476r_end_bytes_up: 477 lb t0, (a1) 478 SUB a2, a2, 0x1 479 sb t0, (a0) 480 ADD a1, a1, 0x1 481 bnez a2, r_end_bytes_up 482 ADD a0, a0, 0x1 483 484 jr ra 485 move a2, zero 486 END(__rmemcpy) 487