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/*
* Copyright 2011 Tilera Corporation. All Rights Reserved.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation, version 2.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
* NON INFRINGEMENT. See the GNU General Public License for
* more details.
*/
#include <linux/types.h>
#include <linux/string.h>
#include <linux/module.h>
#define __memcpy memcpy
/* EXPORT_SYMBOL() is in arch/tile/lib/exports.c since this should be asm. */
/* Must be 8 bytes in size. */
#define word_t uint64_t
#if CHIP_L2_LINE_SIZE() != 64 && CHIP_L2_LINE_SIZE() != 128
#error "Assumes 64 or 128 byte line size"
#endif
/* How many cache lines ahead should we prefetch? */
#define PREFETCH_LINES_AHEAD 3
/*
* Provide "base versions" of load and store for the normal code path.
* The kernel provides other versions for userspace copies.
*/
#define ST(p, v) (*(p) = (v))
#define LD(p) (*(p))
#ifndef USERCOPY_FUNC
#define ST1 ST
#define ST2 ST
#define ST4 ST
#define ST8 ST
#define LD1 LD
#define LD2 LD
#define LD4 LD
#define LD8 LD
#define RETVAL dstv
void *memcpy(void *__restrict dstv, const void *__restrict srcv, size_t n)
#else
/*
* Special kernel version will provide implementation of the LDn/STn
* macros to return a count of uncopied bytes due to mm fault.
*/
#define RETVAL 0
int USERCOPY_FUNC(void *__restrict dstv, const void *__restrict srcv, size_t n)
#endif
{
char *__restrict dst1 = (char *)dstv;
const char *__restrict src1 = (const char *)srcv;
const char *__restrict src1_end;
const char *__restrict prefetch;
word_t *__restrict dst8; /* 8-byte pointer to destination memory. */
word_t final; /* Final bytes to write to trailing word, if any */
long i;
if (n < 16) {
for (; n; n--)
ST1(dst1++, LD1(src1++));
return RETVAL;
}
/*
* Locate the end of source memory we will copy. Don't
* prefetch past this.
*/
src1_end = src1 + n - 1;
/* Prefetch ahead a few cache lines, but not past the end. */
prefetch = src1;
for (i = 0; i < PREFETCH_LINES_AHEAD; i++) {
__insn_prefetch(prefetch);
prefetch += CHIP_L2_LINE_SIZE();
prefetch = (prefetch > src1_end) ? prefetch : src1;
}
/* Copy bytes until dst is word-aligned. */
for (; (uintptr_t)dst1 & (sizeof(word_t) - 1); n--)
ST1(dst1++, LD1(src1++));
/* 8-byte pointer to destination memory. */
dst8 = (word_t *)dst1;
if (__builtin_expect((uintptr_t)src1 & (sizeof(word_t) - 1), 0)) {
/*
* Misaligned copy. Copy 8 bytes at a time, but don't
* bother with other fanciness.
*
* TODO: Consider prefetching and using wh64 as well.
*/
/* Create an aligned src8. */
const word_t *__restrict src8 =
(const word_t *)((uintptr_t)src1 & -sizeof(word_t));
word_t b;
word_t a = LD8(src8++);
for (; n >= sizeof(word_t); n -= sizeof(word_t)) {
b = LD8(src8++);
a = __insn_dblalign(a, b, src1);
ST8(dst8++, a);
a = b;
}
if (n == 0)
return RETVAL;
b = ((const char *)src8 <= src1_end) ? *src8 : 0;
/*
* Final source bytes to write to trailing partial
* word, if any.
*/
final = __insn_dblalign(a, b, src1);
} else {
/* Aligned copy. */
const word_t* __restrict src8 = (const word_t *)src1;
/* src8 and dst8 are both word-aligned. */
if (n >= CHIP_L2_LINE_SIZE()) {
/* Copy until 'dst' is cache-line-aligned. */
for (; (uintptr_t)dst8 & (CHIP_L2_LINE_SIZE() - 1);
n -= sizeof(word_t))
ST8(dst8++, LD8(src8++));
for (; n >= CHIP_L2_LINE_SIZE(); ) {
__insn_wh64(dst8);
/*
* Prefetch and advance to next line
* to prefetch, but don't go past the end
*/
__insn_prefetch(prefetch);
prefetch += CHIP_L2_LINE_SIZE();
prefetch = (prefetch > src1_end) ? prefetch :
(const char *)src8;
/*
* Copy an entire cache line. Manually
* unrolled to avoid idiosyncracies of
* compiler unrolling.
*/
#define COPY_WORD(offset) ({ ST8(dst8+offset, LD8(src8+offset)); n -= 8; })
COPY_WORD(0);
COPY_WORD(1);
COPY_WORD(2);
COPY_WORD(3);
COPY_WORD(4);
COPY_WORD(5);
COPY_WORD(6);
COPY_WORD(7);
#if CHIP_L2_LINE_SIZE() == 128
COPY_WORD(8);
COPY_WORD(9);
COPY_WORD(10);
COPY_WORD(11);
COPY_WORD(12);
COPY_WORD(13);
COPY_WORD(14);
COPY_WORD(15);
#elif CHIP_L2_LINE_SIZE() != 64
# error Fix code that assumes particular L2 cache line sizes
#endif
dst8 += CHIP_L2_LINE_SIZE() / sizeof(word_t);
src8 += CHIP_L2_LINE_SIZE() / sizeof(word_t);
}
}
for (; n >= sizeof(word_t); n -= sizeof(word_t))
ST8(dst8++, LD8(src8++));
if (__builtin_expect(n == 0, 1))
return RETVAL;
final = LD8(src8);
}
/* n != 0 if we get here. Write out any trailing bytes. */
dst1 = (char *)dst8;
if (n & 4) {
ST4((uint32_t *)dst1, final);
dst1 += 4;
final >>= 32;
n &= 3;
}
if (n & 2) {
ST2((uint16_t *)dst1, final);
dst1 += 2;
final >>= 16;
n &= 1;
}
if (n)
ST1((uint8_t *)dst1, final);
return RETVAL;
}
#ifdef USERCOPY_FUNC
#undef ST1
#undef ST2
#undef ST4
#undef ST8
#undef LD1
#undef LD2
#undef LD4
#undef LD8
#undef USERCOPY_FUNC
#endif
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