Loading...
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 | /*
* User address space access functions.
* The non-inlined parts of asm-cris/uaccess.h are here.
*
* Copyright (C) 2000, Axis Communications AB.
*
* Written by Hans-Peter Nilsson.
* Pieces used from memcpy, originally by Kenny Ranerup long time ago.
*/
#include <asm/uaccess.h>
/* Asm:s have been tweaked (within the domain of correctness) to give
satisfactory results for "gcc version 2.96 20000427 (experimental)".
Check regularly...
Note that the PC saved at a bus-fault is the address *after* the
faulting instruction, which means the branch-target for instructions in
delay-slots for taken branches. Note also that the postincrement in
the instruction is performed regardless of bus-fault; the register is
seen updated in fault handlers.
Oh, and on the code formatting issue, to whomever feels like "fixing
it" to Conformity: I'm too "lazy", but why don't you go ahead and "fix"
string.c too. I just don't think too many people will hack this file
for the code format to be an issue. */
/* Copy to userspace. This is based on the memcpy used for
kernel-to-kernel copying; see "string.c". */
unsigned long
__copy_user (void __user *pdst, const void *psrc, unsigned long pn)
{
/* We want the parameters put in special registers.
Make sure the compiler is able to make something useful of this.
As it is now: r10 -> r13; r11 -> r11 (nop); r12 -> r12 (nop).
FIXME: Comment for old gcc version. Check.
If gcc was alright, it really would need no temporaries, and no
stack space to save stuff on. */
register char *dst __asm__ ("r13") = pdst;
register const char *src __asm__ ("r11") = psrc;
register int n __asm__ ("r12") = pn;
register int retn __asm__ ("r10") = 0;
/* When src is aligned but not dst, this makes a few extra needless
cycles. I believe it would take as many to check that the
re-alignment was unnecessary. */
if (((unsigned long) dst & 3) != 0
/* Don't align if we wouldn't copy more than a few bytes; so we
don't have to check further for overflows. */
&& n >= 3)
{
if ((unsigned long) dst & 1)
{
__asm_copy_to_user_1 (dst, src, retn);
n--;
}
if ((unsigned long) dst & 2)
{
__asm_copy_to_user_2 (dst, src, retn);
n -= 2;
}
}
/* Decide which copying method to use. */
if (n >= 44*2) /* Break even between movem and
move16 is at 38.7*2, but modulo 44. */
{
/* For large copies we use 'movem'. */
/* It is not optimal to tell the compiler about clobbering any
registers; that will move the saving/restoring of those registers
to the function prologue/epilogue, and make non-movem sizes
suboptimal.
This method is not foolproof; it assumes that the "asm reg"
declarations at the beginning of the function really are used
here (beware: they may be moved to temporary registers).
This way, we do not have to save/move the registers around into
temporaries; we can safely use them straight away.
If you want to check that the allocation was right; then
check the equalities in the first comment. It should say
"r13=r13, r11=r11, r12=r12". */
__asm__ volatile ("\
.ifnc %0%1%2%3,$r13$r11$r12$r10 \n\
.err \n\
.endif \n\
\n\
;; Save the registers we'll use in the movem process \n\
;; on the stack. \n\
subq 11*4,$sp \n\
movem $r10,[$sp] \n\
\n\
;; Now we've got this: \n\
;; r11 - src \n\
;; r13 - dst \n\
;; r12 - n \n\
\n\
;; Update n for the first loop \n\
subq 44,$r12 \n\
\n\
; Since the noted PC of a faulting instruction in a delay-slot of a taken \n\
; branch, is that of the branch target, we actually point at the from-movem \n\
; for this case. There is no ambiguity here; if there was a fault in that \n\
; instruction (meaning a kernel oops), the faulted PC would be the address \n\
; after *that* movem. \n\
\n\
0: \n\
movem [$r11+],$r10 \n\
subq 44,$r12 \n\
bge 0b \n\
movem $r10,[$r13+] \n\
1: \n\
addq 44,$r12 ;; compensate for last loop underflowing n \n\
\n\
;; Restore registers from stack \n\
movem [$sp+],$r10 \n\
2: \n\
.section .fixup,\"ax\" \n\
\n\
; To provide a correct count in r10 of bytes that failed to be copied, \n\
; we jump back into the loop if the loop-branch was taken. There is no \n\
; performance penalty for sany use; the program will segfault soon enough.\n\
\n\
3: \n\
move.d [$sp],$r10 \n\
addq 44,$r10 \n\
move.d $r10,[$sp] \n\
jump 0b \n\
4: \n\
movem [$sp+],$r10 \n\
addq 44,$r10 \n\
addq 44,$r12 \n\
jump 2b \n\
\n\
.previous \n\
.section __ex_table,\"a\" \n\
.dword 0b,3b \n\
.dword 1b,4b \n\
.previous"
/* Outputs */ : "=r" (dst), "=r" (src), "=r" (n), "=r" (retn)
/* Inputs */ : "0" (dst), "1" (src), "2" (n), "3" (retn));
}
/* Either we directly start copying, using dword copying in a loop, or
we copy as much as possible with 'movem' and then the last block (<44
bytes) is copied here. This will work since 'movem' will have
updated SRC, DST and N. */
while (n >= 16)
{
__asm_copy_to_user_16 (dst, src, retn);
n -= 16;
}
/* Having a separate by-four loops cuts down on cache footprint.
FIXME: Test with and without; increasing switch to be 0..15. */
while (n >= 4)
{
__asm_copy_to_user_4 (dst, src, retn);
n -= 4;
}
switch (n)
{
case 0:
break;
case 1:
__asm_copy_to_user_1 (dst, src, retn);
break;
case 2:
__asm_copy_to_user_2 (dst, src, retn);
break;
case 3:
__asm_copy_to_user_3 (dst, src, retn);
break;
}
return retn;
}
/* Copy from user to kernel, zeroing the bytes that were inaccessible in
userland. The return-value is the number of bytes that were
inaccessible. */
unsigned long
__copy_user_zeroing(void *pdst, const void __user *psrc, unsigned long pn)
{
/* We want the parameters put in special registers.
Make sure the compiler is able to make something useful of this.
As it is now: r10 -> r13; r11 -> r11 (nop); r12 -> r12 (nop).
FIXME: Comment for old gcc version. Check.
If gcc was alright, it really would need no temporaries, and no
stack space to save stuff on. */
register char *dst __asm__ ("r13") = pdst;
register const char *src __asm__ ("r11") = psrc;
register int n __asm__ ("r12") = pn;
register int retn __asm__ ("r10") = 0;
/* The best reason to align src is that we then know that a read-fault
was for aligned bytes; there's no 1..3 remaining good bytes to
pickle. */
if (((unsigned long) src & 3) != 0)
{
if (((unsigned long) src & 1) && n != 0)
{
__asm_copy_from_user_1 (dst, src, retn);
n--;
}
if (((unsigned long) src & 2) && n >= 2)
{
__asm_copy_from_user_2 (dst, src, retn);
n -= 2;
}
/* We only need one check after the unalignment-adjustments, because
if both adjustments were done, either both or neither reference
had an exception. */
if (retn != 0)
goto copy_exception_bytes;
}
/* Decide which copying method to use. */
if (n >= 44*2) /* Break even between movem and
move16 is at 38.7*2, but modulo 44.
FIXME: We use move4 now. */
{
/* For large copies we use 'movem' */
/* It is not optimal to tell the compiler about clobbering any
registers; that will move the saving/restoring of those registers
to the function prologue/epilogue, and make non-movem sizes
suboptimal.
This method is not foolproof; it assumes that the "asm reg"
declarations at the beginning of the function really are used
here (beware: they may be moved to temporary registers).
This way, we do not have to save/move the registers around into
temporaries; we can safely use them straight away.
If you want to check that the allocation was right; then
check the equalities in the first comment. It should say
"r13=r13, r11=r11, r12=r12" */
__asm__ volatile ("\n\
.ifnc %0%1%2%3,$r13$r11$r12$r10 \n\
.err \n\
.endif \n\
\n\
;; Save the registers we'll use in the movem process \n\
;; on the stack. \n\
subq 11*4,$sp \n\
movem $r10,[$sp] \n\
\n\
;; Now we've got this: \n\
;; r11 - src \n\
;; r13 - dst \n\
;; r12 - n \n\
\n\
;; Update n for the first loop \n\
subq 44,$r12 \n\
0: \n\
movem [$r11+],$r10 \n\
1: \n\
subq 44,$r12 \n\
bge 0b \n\
movem $r10,[$r13+] \n\
\n\
addq 44,$r12 ;; compensate for last loop underflowing n \n\
\n\
;; Restore registers from stack \n\
movem [$sp+],$r10 \n\
4: \n\
.section .fixup,\"ax\" \n\
\n\
;; Do not jump back into the loop if we fail. For some uses, we get a \n\
;; page fault somewhere on the line. Without checking for page limits, \n\
;; we don't know where, but we need to copy accurately and keep an \n\
;; accurate count; not just clear the whole line. To do that, we fall \n\
;; down in the code below, proceeding with smaller amounts. It should \n\
;; be kept in mind that we have to cater to code like what at one time \n\
;; was in fs/super.c: \n\
;; i = size - copy_from_user((void *)page, data, size); \n\
;; which would cause repeated faults while clearing the remainder of \n\
;; the SIZE bytes at PAGE after the first fault. \n\
;; A caveat here is that we must not fall through from a failing page \n\
;; to a valid page. \n\
\n\
3: \n\
movem [$sp+],$r10 \n\
addq 44,$r12 ;; Get back count before faulting point. \n\
subq 44,$r11 ;; Get back pointer to faulting movem-line. \n\
jump 4b ;; Fall through, pretending the fault didn't happen.\n\
\n\
.previous \n\
.section __ex_table,\"a\" \n\
.dword 1b,3b \n\
.previous"
/* Outputs */ : "=r" (dst), "=r" (src), "=r" (n), "=r" (retn)
/* Inputs */ : "0" (dst), "1" (src), "2" (n), "3" (retn));
}
/* Either we directly start copying here, using dword copying in a loop,
or we copy as much as possible with 'movem' and then the last block
(<44 bytes) is copied here. This will work since 'movem' will have
updated src, dst and n. (Except with failing src.)
Since we want to keep src accurate, we can't use
__asm_copy_from_user_N with N != (1, 2, 4); it updates dst and
retn, but not src (by design; it's value is ignored elsewhere). */
while (n >= 4)
{
__asm_copy_from_user_4 (dst, src, retn);
n -= 4;
if (retn)
goto copy_exception_bytes;
}
/* If we get here, there were no memory read faults. */
switch (n)
{
/* These copies are at least "naturally aligned" (so we don't have
to check each byte), due to the src alignment code before the
movem loop. The *_3 case *will* get the correct count for retn. */
case 0:
/* This case deliberately left in (if you have doubts check the
generated assembly code). */
break;
case 1:
__asm_copy_from_user_1 (dst, src, retn);
break;
case 2:
__asm_copy_from_user_2 (dst, src, retn);
break;
case 3:
__asm_copy_from_user_3 (dst, src, retn);
break;
}
/* If we get here, retn correctly reflects the number of failing
bytes. */
return retn;
copy_exception_bytes:
/* We already have "retn" bytes cleared, and need to clear the
remaining "n" bytes. A non-optimized simple byte-for-byte in-line
memset is preferred here, since this isn't speed-critical code and
we'd rather have this a leaf-function than calling memset. */
{
char *endp;
for (endp = dst + n; dst < endp; dst++)
*dst = 0;
}
return retn + n;
}
/* Zero userspace. */
unsigned long
__do_clear_user (void __user *pto, unsigned long pn)
{
/* We want the parameters put in special registers.
Make sure the compiler is able to make something useful of this.
As it is now: r10 -> r13; r11 -> r11 (nop); r12 -> r12 (nop).
FIXME: Comment for old gcc version. Check.
If gcc was alright, it really would need no temporaries, and no
stack space to save stuff on. */
register char *dst __asm__ ("r13") = pto;
register int n __asm__ ("r12") = pn;
register int retn __asm__ ("r10") = 0;
if (((unsigned long) dst & 3) != 0
/* Don't align if we wouldn't copy more than a few bytes. */
&& n >= 3)
{
if ((unsigned long) dst & 1)
{
__asm_clear_1 (dst, retn);
n--;
}
if ((unsigned long) dst & 2)
{
__asm_clear_2 (dst, retn);
n -= 2;
}
}
/* Decide which copying method to use.
FIXME: This number is from the "ordinary" kernel memset. */
if (n >= (1*48))
{
/* For large clears we use 'movem' */
/* It is not optimal to tell the compiler about clobbering any
call-saved registers; that will move the saving/restoring of
those registers to the function prologue/epilogue, and make
non-movem sizes suboptimal.
This method is not foolproof; it assumes that the "asm reg"
declarations at the beginning of the function really are used
here (beware: they may be moved to temporary registers).
This way, we do not have to save/move the registers around into
temporaries; we can safely use them straight away.
If you want to check that the allocation was right; then
check the equalities in the first comment. It should say
something like "r13=r13, r11=r11, r12=r12". */
__asm__ volatile ("\n\
.ifnc %0%1%2,$r13$r12$r10 \n\
.err \n\
.endif \n\
\n\
;; Save the registers we'll clobber in the movem process \n\
;; on the stack. Don't mention them to gcc, it will only be \n\
;; upset. \n\
subq 11*4,$sp \n\
movem $r10,[$sp] \n\
\n\
clear.d $r0 \n\
clear.d $r1 \n\
clear.d $r2 \n\
clear.d $r3 \n\
clear.d $r4 \n\
clear.d $r5 \n\
clear.d $r6 \n\
clear.d $r7 \n\
clear.d $r8 \n\
clear.d $r9 \n\
clear.d $r10 \n\
clear.d $r11 \n\
\n\
;; Now we've got this: \n\
;; r13 - dst \n\
;; r12 - n \n\
\n\
;; Update n for the first loop \n\
subq 12*4,$r12 \n\
0: \n\
subq 12*4,$r12 \n\
bge 0b \n\
movem $r11,[$r13+] \n\
1: \n\
addq 12*4,$r12 ;; compensate for last loop underflowing n\n\
\n\
;; Restore registers from stack \n\
movem [$sp+],$r10 \n\
2: \n\
.section .fixup,\"ax\" \n\
3: \n\
move.d [$sp],$r10 \n\
addq 12*4,$r10 \n\
move.d $r10,[$sp] \n\
clear.d $r10 \n\
jump 0b \n\
\n\
4: \n\
movem [$sp+],$r10 \n\
addq 12*4,$r10 \n\
addq 12*4,$r12 \n\
jump 2b \n\
\n\
.previous \n\
.section __ex_table,\"a\" \n\
.dword 0b,3b \n\
.dword 1b,4b \n\
.previous"
/* Outputs */ : "=r" (dst), "=r" (n), "=r" (retn)
/* Inputs */ : "0" (dst), "1" (n), "2" (retn)
/* Clobber */ : "r11");
}
while (n >= 16)
{
__asm_clear_16 (dst, retn);
n -= 16;
}
/* Having a separate by-four loops cuts down on cache footprint.
FIXME: Test with and without; increasing switch to be 0..15. */
while (n >= 4)
{
__asm_clear_4 (dst, retn);
n -= 4;
}
switch (n)
{
case 0:
break;
case 1:
__asm_clear_1 (dst, retn);
break;
case 2:
__asm_clear_2 (dst, retn);
break;
case 3:
__asm_clear_3 (dst, retn);
break;
}
return retn;
}
|