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 * t7 is used as a flag to note inatomic mode. 144 */ 145LEAF(__copy_user_inatomic) 146EXPORT_SYMBOL(__copy_user_inatomic) 147 b __copy_user_common 148 li t7, 1 149 END(__copy_user_inatomic) 150 151/* 152 * A combined memcpy/__copy_user 153 * __copy_user sets len to 0 for success; else to an upper bound of 154 * the number of uncopied bytes. 155 * memcpy sets v0 to dst. 156 */ 157 .align 5 158LEAF(memcpy) /* a0=dst a1=src a2=len */ 159EXPORT_SYMBOL(memcpy) 160 move v0, dst /* return value */ 161__memcpy: 162FEXPORT(__copy_user) 163EXPORT_SYMBOL(__copy_user) 164 li t7, 0 /* not inatomic */ 165__copy_user_common: 166 /* 167 * Note: dst & src may be unaligned, len may be 0 168 * Temps 169 */ 170 # 171 # Octeon doesn't care if the destination is unaligned. The hardware 172 # can fix it faster than we can special case the assembly. 173 # 174 pref 0, 0(src) 175 sltu t0, len, NBYTES # Check if < 1 word 176 bnez t0, copy_bytes_checklen 177 and t0, src, ADDRMASK # Check if src unaligned 178 bnez t0, src_unaligned 179 sltu t0, len, 4*NBYTES # Check if < 4 words 180 bnez t0, less_than_4units 181 sltu t0, len, 8*NBYTES # Check if < 8 words 182 bnez t0, less_than_8units 183 sltu t0, len, 16*NBYTES # Check if < 16 words 184 bnez t0, cleanup_both_aligned 185 sltu t0, len, 128+1 # Check if len < 129 186 bnez t0, 1f # Skip prefetch if len is too short 187 sltu t0, len, 256+1 # Check if len < 257 188 bnez t0, 1f # Skip prefetch if len is too short 189 pref 0, 128(src) # We must not prefetch invalid addresses 190 # 191 # This is where we loop if there is more than 128 bytes left 1922: pref 0, 256(src) # We must not prefetch invalid addresses 193 # 194 # This is where we loop if we can't prefetch anymore 1951: 196EXC( LOAD t0, UNIT(0)(src), l_exc) 197EXC( LOAD t1, UNIT(1)(src), l_exc_copy) 198EXC( LOAD t2, UNIT(2)(src), l_exc_copy) 199EXC( LOAD t3, UNIT(3)(src), l_exc_copy) 200 SUB len, len, 16*NBYTES 201EXC( STORE t0, UNIT(0)(dst), s_exc_p16u) 202EXC( STORE t1, UNIT(1)(dst), s_exc_p15u) 203EXC( STORE t2, UNIT(2)(dst), s_exc_p14u) 204EXC( STORE t3, UNIT(3)(dst), s_exc_p13u) 205EXC( LOAD t0, UNIT(4)(src), l_exc_copy) 206EXC( LOAD t1, UNIT(5)(src), l_exc_copy) 207EXC( LOAD t2, UNIT(6)(src), l_exc_copy) 208EXC( LOAD t3, UNIT(7)(src), l_exc_copy) 209EXC( STORE t0, UNIT(4)(dst), s_exc_p12u) 210EXC( STORE t1, UNIT(5)(dst), s_exc_p11u) 211EXC( STORE t2, UNIT(6)(dst), s_exc_p10u) 212 ADD src, src, 16*NBYTES 213EXC( STORE t3, UNIT(7)(dst), s_exc_p9u) 214 ADD dst, dst, 16*NBYTES 215EXC( LOAD t0, UNIT(-8)(src), l_exc_copy_rewind16) 216EXC( LOAD t1, UNIT(-7)(src), l_exc_copy_rewind16) 217EXC( LOAD t2, UNIT(-6)(src), l_exc_copy_rewind16) 218EXC( LOAD t3, UNIT(-5)(src), l_exc_copy_rewind16) 219EXC( STORE t0, UNIT(-8)(dst), s_exc_p8u) 220EXC( STORE t1, UNIT(-7)(dst), s_exc_p7u) 221EXC( STORE t2, UNIT(-6)(dst), s_exc_p6u) 222EXC( STORE t3, UNIT(-5)(dst), s_exc_p5u) 223EXC( LOAD t0, UNIT(-4)(src), l_exc_copy_rewind16) 224EXC( LOAD t1, UNIT(-3)(src), l_exc_copy_rewind16) 225EXC( LOAD t2, UNIT(-2)(src), l_exc_copy_rewind16) 226EXC( LOAD t3, UNIT(-1)(src), l_exc_copy_rewind16) 227EXC( STORE t0, UNIT(-4)(dst), s_exc_p4u) 228EXC( STORE t1, UNIT(-3)(dst), s_exc_p3u) 229EXC( STORE t2, UNIT(-2)(dst), s_exc_p2u) 230EXC( STORE t3, UNIT(-1)(dst), s_exc_p1u) 231 sltu t0, len, 256+1 # See if we can prefetch more 232 beqz t0, 2b 233 sltu t0, len, 128 # See if we can loop more time 234 beqz t0, 1b 235 nop 236 # 237 # Jump here if there are less than 16*NBYTES left. 238 # 239cleanup_both_aligned: 240 beqz len, done 241 sltu t0, len, 8*NBYTES 242 bnez t0, less_than_8units 243 nop 244EXC( LOAD t0, UNIT(0)(src), l_exc) 245EXC( LOAD t1, UNIT(1)(src), l_exc_copy) 246EXC( LOAD t2, UNIT(2)(src), l_exc_copy) 247EXC( LOAD t3, UNIT(3)(src), l_exc_copy) 248 SUB len, len, 8*NBYTES 249EXC( STORE t0, UNIT(0)(dst), s_exc_p8u) 250EXC( STORE t1, UNIT(1)(dst), s_exc_p7u) 251EXC( STORE t2, UNIT(2)(dst), s_exc_p6u) 252EXC( STORE t3, UNIT(3)(dst), s_exc_p5u) 253EXC( LOAD t0, UNIT(4)(src), l_exc_copy) 254EXC( LOAD t1, UNIT(5)(src), l_exc_copy) 255EXC( LOAD t2, UNIT(6)(src), l_exc_copy) 256EXC( LOAD t3, UNIT(7)(src), l_exc_copy) 257EXC( STORE t0, UNIT(4)(dst), s_exc_p4u) 258EXC( STORE t1, UNIT(5)(dst), s_exc_p3u) 259EXC( STORE t2, UNIT(6)(dst), s_exc_p2u) 260EXC( STORE t3, UNIT(7)(dst), s_exc_p1u) 261 ADD src, src, 8*NBYTES 262 beqz len, done 263 ADD dst, dst, 8*NBYTES 264 # 265 # Jump here if there are less than 8*NBYTES left. 266 # 267less_than_8units: 268 sltu t0, len, 4*NBYTES 269 bnez t0, less_than_4units 270 nop 271EXC( LOAD t0, UNIT(0)(src), l_exc) 272EXC( LOAD t1, UNIT(1)(src), l_exc_copy) 273EXC( LOAD t2, UNIT(2)(src), l_exc_copy) 274EXC( LOAD t3, UNIT(3)(src), l_exc_copy) 275 SUB len, len, 4*NBYTES 276EXC( STORE t0, UNIT(0)(dst), s_exc_p4u) 277EXC( STORE t1, UNIT(1)(dst), s_exc_p3u) 278EXC( STORE t2, UNIT(2)(dst), s_exc_p2u) 279EXC( STORE t3, UNIT(3)(dst), s_exc_p1u) 280 ADD src, src, 4*NBYTES 281 beqz len, done 282 ADD dst, dst, 4*NBYTES 283 # 284 # Jump here if there are less than 4*NBYTES left. This means 285 # we may need to copy up to 3 NBYTES words. 286 # 287less_than_4units: 288 sltu t0, len, 1*NBYTES 289 bnez t0, copy_bytes_checklen 290 nop 291 # 292 # 1) Copy NBYTES, then check length again 293 # 294EXC( LOAD t0, 0(src), l_exc) 295 SUB len, len, NBYTES 296 sltu t1, len, 8 297EXC( STORE t0, 0(dst), s_exc_p1u) 298 ADD src, src, NBYTES 299 bnez t1, copy_bytes_checklen 300 ADD dst, dst, NBYTES 301 # 302 # 2) Copy NBYTES, then check length again 303 # 304EXC( LOAD t0, 0(src), l_exc) 305 SUB len, len, NBYTES 306 sltu t1, len, 8 307EXC( STORE t0, 0(dst), s_exc_p1u) 308 ADD src, src, NBYTES 309 bnez t1, copy_bytes_checklen 310 ADD dst, dst, NBYTES 311 # 312 # 3) Copy NBYTES, then check length again 313 # 314EXC( LOAD t0, 0(src), l_exc) 315 SUB len, len, NBYTES 316 ADD src, src, NBYTES 317 ADD dst, dst, NBYTES 318 b copy_bytes_checklen 319EXC( STORE t0, -8(dst), s_exc_p1u) 320 321src_unaligned: 322#define rem t8 323 SRL t0, len, LOG_NBYTES+2 # +2 for 4 units/iter 324 beqz t0, cleanup_src_unaligned 325 and rem, len, (4*NBYTES-1) # rem = len % 4*NBYTES 3261: 327/* 328 * Avoid consecutive LD*'s to the same register since some mips 329 * implementations can't issue them in the same cycle. 330 * It's OK to load FIRST(N+1) before REST(N) because the two addresses 331 * are to the same unit (unless src is aligned, but it's not). 332 */ 333EXC( LDFIRST t0, FIRST(0)(src), l_exc) 334EXC( LDFIRST t1, FIRST(1)(src), l_exc_copy) 335 SUB len, len, 4*NBYTES 336EXC( LDREST t0, REST(0)(src), l_exc_copy) 337EXC( LDREST t1, REST(1)(src), l_exc_copy) 338EXC( LDFIRST t2, FIRST(2)(src), l_exc_copy) 339EXC( LDFIRST t3, FIRST(3)(src), l_exc_copy) 340EXC( LDREST t2, REST(2)(src), l_exc_copy) 341EXC( LDREST t3, REST(3)(src), l_exc_copy) 342 ADD src, src, 4*NBYTES 343EXC( STORE t0, UNIT(0)(dst), s_exc_p4u) 344EXC( STORE t1, UNIT(1)(dst), s_exc_p3u) 345EXC( STORE t2, UNIT(2)(dst), s_exc_p2u) 346EXC( STORE t3, UNIT(3)(dst), s_exc_p1u) 347 bne len, rem, 1b 348 ADD dst, dst, 4*NBYTES 349 350cleanup_src_unaligned: 351 beqz len, done 352 and rem, len, NBYTES-1 # rem = len % NBYTES 353 beq rem, len, copy_bytes 354 nop 3551: 356EXC( LDFIRST t0, FIRST(0)(src), l_exc) 357EXC( LDREST t0, REST(0)(src), l_exc_copy) 358 SUB len, len, NBYTES 359EXC( STORE t0, 0(dst), s_exc_p1u) 360 ADD src, src, NBYTES 361 bne len, rem, 1b 362 ADD dst, dst, NBYTES 363 364copy_bytes_checklen: 365 beqz len, done 366 nop 367copy_bytes: 368 /* 0 < len < NBYTES */ 369#define COPY_BYTE(N) \ 370EXC( lb t0, N(src), l_exc); \ 371 SUB len, len, 1; \ 372 beqz len, done; \ 373EXC( sb t0, N(dst), s_exc_p1) 374 375 COPY_BYTE(0) 376 COPY_BYTE(1) 377 COPY_BYTE(2) 378 COPY_BYTE(3) 379 COPY_BYTE(4) 380 COPY_BYTE(5) 381EXC( lb t0, NBYTES-2(src), l_exc) 382 SUB len, len, 1 383 jr ra 384EXC( sb t0, NBYTES-2(dst), s_exc_p1) 385done: 386 jr ra 387 nop 388 END(memcpy) 389 390l_exc_copy_rewind16: 391 /* Rewind src and dst by 16*NBYTES for l_exc_copy */ 392 SUB src, src, 16*NBYTES 393 SUB dst, dst, 16*NBYTES 394l_exc_copy: 395 /* 396 * Copy bytes from src until faulting load address (or until a 397 * lb faults) 398 * 399 * When reached by a faulting LDFIRST/LDREST, THREAD_BUADDR($28) 400 * may be more than a byte beyond the last address. 401 * Hence, the lb below may get an exception. 402 * 403 * Assumes src < THREAD_BUADDR($28) 404 */ 405 LOAD t0, TI_TASK($28) 406 LOAD t0, THREAD_BUADDR(t0) 4071: 408EXC( lb t1, 0(src), l_exc) 409 ADD src, src, 1 410 sb t1, 0(dst) # can't fault -- we're copy_from_user 411 bne src, t0, 1b 412 ADD dst, dst, 1 413l_exc: 414 LOAD t0, TI_TASK($28) 415 LOAD t0, THREAD_BUADDR(t0) # t0 is just past last good address 416 SUB len, AT, t0 # len number of uncopied bytes 417 bnez t7, 2f /* Skip the zeroing out part if inatomic */ 418 /* 419 * Here's where we rely on src and dst being incremented in tandem, 420 * See (3) above. 421 * dst += (fault addr - src) to put dst at first byte to clear 422 */ 423 ADD dst, t0 # compute start address in a1 424 SUB dst, src 425 /* 426 * Clear len bytes starting at dst. Can't call __bzero because it 427 * might modify len. An inefficient loop for these rare times... 428 */ 429 beqz len, done 430 SUB src, len, 1 4311: sb zero, 0(dst) 432 ADD dst, dst, 1 433 bnez src, 1b 434 SUB src, src, 1 4352: jr ra 436 nop 437 438 439#define SEXC(n) \ 440s_exc_p ## n ## u: \ 441 jr ra; \ 442 ADD len, len, n*NBYTES 443 444SEXC(16) 445SEXC(15) 446SEXC(14) 447SEXC(13) 448SEXC(12) 449SEXC(11) 450SEXC(10) 451SEXC(9) 452SEXC(8) 453SEXC(7) 454SEXC(6) 455SEXC(5) 456SEXC(4) 457SEXC(3) 458SEXC(2) 459SEXC(1) 460 461s_exc_p1: 462 jr ra 463 ADD len, len, 1 464s_exc: 465 jr ra 466 nop 467 468 .align 5 469LEAF(memmove) 470EXPORT_SYMBOL(memmove) 471 ADD t0, a0, a2 472 ADD t1, a1, a2 473 sltu t0, a1, t0 # dst + len <= src -> memcpy 474 sltu t1, a0, t1 # dst >= src + len -> memcpy 475 and t0, t1 476 beqz t0, __memcpy 477 move v0, a0 /* return value */ 478 beqz a2, r_out 479 END(memmove) 480 481 /* fall through to __rmemcpy */ 482LEAF(__rmemcpy) /* a0=dst a1=src a2=len */ 483 sltu t0, a1, a0 484 beqz t0, r_end_bytes_up # src >= dst 485 nop 486 ADD a0, a2 # dst = dst + len 487 ADD a1, a2 # src = src + len 488 489r_end_bytes: 490 lb t0, -1(a1) 491 SUB a2, a2, 0x1 492 sb t0, -1(a0) 493 SUB a1, a1, 0x1 494 bnez a2, r_end_bytes 495 SUB a0, a0, 0x1 496 497r_out: 498 jr ra 499 move a2, zero 500 501r_end_bytes_up: 502 lb t0, (a1) 503 SUB a2, a2, 0x1 504 sb t0, (a0) 505 ADD a1, a1, 0x1 506 bnez a2, r_end_bytes_up 507 ADD a0, a0, 0x1 508 509 jr ra 510 move a2, zero 511 END(__rmemcpy) 512