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linux/arch/parisc/lib/memcpy.c

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/*
* Optimized memory copy routines.
*
* Copyright (C) 2004 Randolph Chung <tausq@debian.org>
*
* 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; either version 2, or (at your option)
* any later version.
*
* 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. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*
* Portions derived from the GNU C Library
* Copyright (C) 1991, 1997, 2003 Free Software Foundation, Inc.
*
* Several strategies are tried to try to get the best performance for various
* conditions. In the optimal case, we copy 64-bytes in an unrolled loop using
* fp regs. This is followed by loops that copy 32- or 16-bytes at a time using
* general registers. Unaligned copies are handled either by aligning the
* destination and then using shift-and-write method, or in a few cases by
* falling back to a byte-at-a-time copy.
*
* I chose to implement this in C because it is easier to maintain and debug,
* and in my experiments it appears that the C code generated by gcc (3.3/3.4
* at the time of writing) is fairly optimal. Unfortunately some of the
* semantics of the copy routine (exception handling) is difficult to express
* in C, so we have to play some tricks to get it to work.
*
* All the loads and stores are done via explicit asm() code in order to use
* the right space registers.
*
* Testing with various alignments and buffer sizes shows that this code is
* often >10x faster than a simple byte-at-a-time copy, even for strangely
* aligned operands. It is interesting to note that the glibc version
* of memcpy (written in C) is actually quite fast already. This routine is
* able to beat it by 30-40% for aligned copies because of the loop unrolling,
* but in some cases the glibc version is still slightly faster. This lends
* more credibility that gcc can generate very good code as long as we are
* careful.
*
* TODO:
* - cache prefetching needs more experimentation to get optimal settings
* - try not to use the post-increment address modifiers; they create additional
* interlocks
* - replace byte-copy loops with stybs sequences
*/
#ifdef __KERNEL__
#include <linux/module.h>
#include <linux/compiler.h>
#include <asm/uaccess.h>
#define s_space "%%sr1"
#define d_space "%%sr2"
#else
#include "memcpy.h"
#define s_space "%%sr0"
#define d_space "%%sr0"
#define pa_memcpy new2_copy
#endif
DECLARE_PER_CPU(struct exception_data, exception_data);
#define preserve_branch(label) do { \
volatile int dummy; \
/* The following branch is never taken, it's just here to */ \
/* prevent gcc from optimizing away our exception code. */ \
if (unlikely(dummy != dummy)) \
goto label; \
} while (0)
#define get_user_space() (segment_eq(get_fs(), KERNEL_DS) ? 0 : mfsp(3))
#define get_kernel_space() (0)
#define MERGE(w0, sh_1, w1, sh_2) ({ \
unsigned int _r; \
asm volatile ( \
"mtsar %3\n" \
"shrpw %1, %2, %%sar, %0\n" \
: "=r"(_r) \
: "r"(w0), "r"(w1), "r"(sh_2) \
); \
_r; \
})
#define THRESHOLD 16
#ifdef DEBUG_MEMCPY
#define DPRINTF(fmt, args...) do { printk(KERN_DEBUG "%s:%d:%s ", __FILE__, __LINE__, __func__ ); printk(KERN_DEBUG fmt, ##args ); } while (0)
#else
#define DPRINTF(fmt, args...)
#endif
#define def_load_ai_insn(_insn,_sz,_tt,_s,_a,_t,_e) \
__asm__ __volatile__ ( \
"1:\t" #_insn ",ma " #_sz "(" _s ",%1), %0\n\t" \
ASM_EXCEPTIONTABLE_ENTRY(1b,_e) \
: _tt(_t), "+r"(_a) \
: \
: "r8")
#define def_store_ai_insn(_insn,_sz,_tt,_s,_a,_t,_e) \
__asm__ __volatile__ ( \
"1:\t" #_insn ",ma %1, " #_sz "(" _s ",%0)\n\t" \
ASM_EXCEPTIONTABLE_ENTRY(1b,_e) \
: "+r"(_a) \
: _tt(_t) \
: "r8")
#define ldbma(_s, _a, _t, _e) def_load_ai_insn(ldbs,1,"=r",_s,_a,_t,_e)
#define stbma(_s, _t, _a, _e) def_store_ai_insn(stbs,1,"r",_s,_a,_t,_e)
#define ldwma(_s, _a, _t, _e) def_load_ai_insn(ldw,4,"=r",_s,_a,_t,_e)
#define stwma(_s, _t, _a, _e) def_store_ai_insn(stw,4,"r",_s,_a,_t,_e)
#define flddma(_s, _a, _t, _e) def_load_ai_insn(fldd,8,"=f",_s,_a,_t,_e)
#define fstdma(_s, _t, _a, _e) def_store_ai_insn(fstd,8,"f",_s,_a,_t,_e)
#define def_load_insn(_insn,_tt,_s,_o,_a,_t,_e) \
__asm__ __volatile__ ( \
"1:\t" #_insn " " #_o "(" _s ",%1), %0\n\t" \
ASM_EXCEPTIONTABLE_ENTRY(1b,_e) \
: _tt(_t) \
: "r"(_a) \
: "r8")
#define def_store_insn(_insn,_tt,_s,_t,_o,_a,_e) \
__asm__ __volatile__ ( \
"1:\t" #_insn " %0, " #_o "(" _s ",%1)\n\t" \
ASM_EXCEPTIONTABLE_ENTRY(1b,_e) \
: \
: _tt(_t), "r"(_a) \
: "r8")
#define ldw(_s,_o,_a,_t,_e) def_load_insn(ldw,"=r",_s,_o,_a,_t,_e)
#define stw(_s,_t,_o,_a,_e) def_store_insn(stw,"r",_s,_t,_o,_a,_e)
#ifdef CONFIG_PREFETCH
static inline void prefetch_src(const void *addr)
{
__asm__("ldw 0(" s_space ",%0), %%r0" : : "r" (addr));
}
static inline void prefetch_dst(const void *addr)
{
__asm__("ldd 0(" d_space ",%0), %%r0" : : "r" (addr));
}
#else
#define prefetch_src(addr) do { } while(0)
#define prefetch_dst(addr) do { } while(0)
#endif
/* Copy from a not-aligned src to an aligned dst, using shifts. Handles 4 words
* per loop. This code is derived from glibc.
*/
static inline unsigned long copy_dstaligned(unsigned long dst, unsigned long src, unsigned long len, unsigned long o_dst, unsigned long o_src, unsigned long o_len)
{
/* gcc complains that a2 and a3 may be uninitialized, but actually
* they cannot be. Initialize a2/a3 to shut gcc up.
*/
register unsigned int a0, a1, a2 = 0, a3 = 0;
int sh_1, sh_2;
struct exception_data *d;
/* prefetch_src((const void *)src); */
/* Calculate how to shift a word read at the memory operation
aligned srcp to make it aligned for copy. */
sh_1 = 8 * (src % sizeof(unsigned int));
sh_2 = 8 * sizeof(unsigned int) - sh_1;
/* Make src aligned by rounding it down. */
src &= -sizeof(unsigned int);
switch (len % 4)
{
case 2:
/* a1 = ((unsigned int *) src)[0];
a2 = ((unsigned int *) src)[1]; */
ldw(s_space, 0, src, a1, cda_ldw_exc);
ldw(s_space, 4, src, a2, cda_ldw_exc);
src -= 1 * sizeof(unsigned int);
dst -= 3 * sizeof(unsigned int);
len += 2;
goto do1;
case 3:
/* a0 = ((unsigned int *) src)[0];
a1 = ((unsigned int *) src)[1]; */
ldw(s_space, 0, src, a0, cda_ldw_exc);
ldw(s_space, 4, src, a1, cda_ldw_exc);
src -= 0 * sizeof(unsigned int);
dst -= 2 * sizeof(unsigned int);
len += 1;
goto do2;
case 0:
if (len == 0)
return 0;
/* a3 = ((unsigned int *) src)[0];
a0 = ((unsigned int *) src)[1]; */
ldw(s_space, 0, src, a3, cda_ldw_exc);
ldw(s_space, 4, src, a0, cda_ldw_exc);
src -=-1 * sizeof(unsigned int);
dst -= 1 * sizeof(unsigned int);
len += 0;
goto do3;
case 1:
/* a2 = ((unsigned int *) src)[0];
a3 = ((unsigned int *) src)[1]; */
ldw(s_space, 0, src, a2, cda_ldw_exc);
ldw(s_space, 4, src, a3, cda_ldw_exc);
src -=-2 * sizeof(unsigned int);
dst -= 0 * sizeof(unsigned int);
len -= 1;
if (len == 0)
goto do0;
goto do4; /* No-op. */
}
do
{
/* prefetch_src((const void *)(src + 4 * sizeof(unsigned int))); */
do4:
/* a0 = ((unsigned int *) src)[0]; */
ldw(s_space, 0, src, a0, cda_ldw_exc);
/* ((unsigned int *) dst)[0] = MERGE (a2, sh_1, a3, sh_2); */
stw(d_space, MERGE (a2, sh_1, a3, sh_2), 0, dst, cda_stw_exc);
do3:
/* a1 = ((unsigned int *) src)[1]; */
ldw(s_space, 4, src, a1, cda_ldw_exc);
/* ((unsigned int *) dst)[1] = MERGE (a3, sh_1, a0, sh_2); */
stw(d_space, MERGE (a3, sh_1, a0, sh_2), 4, dst, cda_stw_exc);
do2:
/* a2 = ((unsigned int *) src)[2]; */
ldw(s_space, 8, src, a2, cda_ldw_exc);
/* ((unsigned int *) dst)[2] = MERGE (a0, sh_1, a1, sh_2); */
stw(d_space, MERGE (a0, sh_1, a1, sh_2), 8, dst, cda_stw_exc);
do1:
/* a3 = ((unsigned int *) src)[3]; */
ldw(s_space, 12, src, a3, cda_ldw_exc);
/* ((unsigned int *) dst)[3] = MERGE (a1, sh_1, a2, sh_2); */
stw(d_space, MERGE (a1, sh_1, a2, sh_2), 12, dst, cda_stw_exc);
src += 4 * sizeof(unsigned int);
dst += 4 * sizeof(unsigned int);
len -= 4;
}
while (len != 0);
do0:
/* ((unsigned int *) dst)[0] = MERGE (a2, sh_1, a3, sh_2); */
stw(d_space, MERGE (a2, sh_1, a3, sh_2), 0, dst, cda_stw_exc);
preserve_branch(handle_load_error);
preserve_branch(handle_store_error);
return 0;
handle_load_error:
__asm__ __volatile__ ("cda_ldw_exc:\n");
d = &__get_cpu_var(exception_data);
DPRINTF("cda_ldw_exc: o_len=%lu fault_addr=%lu o_src=%lu ret=%lu\n",
o_len, d->fault_addr, o_src, o_len - d->fault_addr + o_src);
return o_len * 4 - d->fault_addr + o_src;
handle_store_error:
__asm__ __volatile__ ("cda_stw_exc:\n");
d = &__get_cpu_var(exception_data);
DPRINTF("cda_stw_exc: o_len=%lu fault_addr=%lu o_dst=%lu ret=%lu\n",
o_len, d->fault_addr, o_dst, o_len - d->fault_addr + o_dst);
return o_len * 4 - d->fault_addr + o_dst;
}
/* Returns 0 for success, otherwise, returns number of bytes not transferred. */
static unsigned long pa_memcpy(void *dstp, const void *srcp, unsigned long len)
{
register unsigned long src, dst, t1, t2, t3;
register unsigned char *pcs, *pcd;
register unsigned int *pws, *pwd;
register double *pds, *pdd;
unsigned long ret = 0;
unsigned long o_dst, o_src, o_len;
struct exception_data *d;
src = (unsigned long)srcp;
dst = (unsigned long)dstp;
pcs = (unsigned char *)srcp;
pcd = (unsigned char *)dstp;
o_dst = dst; o_src = src; o_len = len;
/* prefetch_src((const void *)srcp); */
if (len < THRESHOLD)
goto byte_copy;
/* Check alignment */
t1 = (src ^ dst);
if (unlikely(t1 & (sizeof(double)-1)))
goto unaligned_copy;
/* src and dst have same alignment. */
/* Copy bytes till we are double-aligned. */
t2 = src & (sizeof(double) - 1);
if (unlikely(t2 != 0)) {
t2 = sizeof(double) - t2;
while (t2 && len) {
/* *pcd++ = *pcs++; */
ldbma(s_space, pcs, t3, pmc_load_exc);
len--;
stbma(d_space, t3, pcd, pmc_store_exc);
t2--;
}
}
pds = (double *)pcs;
pdd = (double *)pcd;
#if 0
/* Copy 8 doubles at a time */
while (len >= 8*sizeof(double)) {
register double r1, r2, r3, r4, r5, r6, r7, r8;
/* prefetch_src((char *)pds + L1_CACHE_BYTES); */
flddma(s_space, pds, r1, pmc_load_exc);
flddma(s_space, pds, r2, pmc_load_exc);
flddma(s_space, pds, r3, pmc_load_exc);
flddma(s_space, pds, r4, pmc_load_exc);
fstdma(d_space, r1, pdd, pmc_store_exc);
fstdma(d_space, r2, pdd, pmc_store_exc);
fstdma(d_space, r3, pdd, pmc_store_exc);
fstdma(d_space, r4, pdd, pmc_store_exc);
#if 0
if (L1_CACHE_BYTES <= 32)
prefetch_src((char *)pds + L1_CACHE_BYTES);
#endif
flddma(s_space, pds, r5, pmc_load_exc);
flddma(s_space, pds, r6, pmc_load_exc);
flddma(s_space, pds, r7, pmc_load_exc);
flddma(s_space, pds, r8, pmc_load_exc);
fstdma(d_space, r5, pdd, pmc_store_exc);
fstdma(d_space, r6, pdd, pmc_store_exc);
fstdma(d_space, r7, pdd, pmc_store_exc);
fstdma(d_space, r8, pdd, pmc_store_exc);
len -= 8*sizeof(double);
}
#endif
pws = (unsigned int *)pds;
pwd = (unsigned int *)pdd;
word_copy:
while (len >= 8*sizeof(unsigned int)) {
register unsigned int r1,r2,r3,r4,r5,r6,r7,r8;
/* prefetch_src((char *)pws + L1_CACHE_BYTES); */
ldwma(s_space, pws, r1, pmc_load_exc);
ldwma(s_space, pws, r2, pmc_load_exc);
ldwma(s_space, pws, r3, pmc_load_exc);
ldwma(s_space, pws, r4, pmc_load_exc);
stwma(d_space, r1, pwd, pmc_store_exc);
stwma(d_space, r2, pwd, pmc_store_exc);
stwma(d_space, r3, pwd, pmc_store_exc);
stwma(d_space, r4, pwd, pmc_store_exc);
ldwma(s_space, pws, r5, pmc_load_exc);
ldwma(s_space, pws, r6, pmc_load_exc);
ldwma(s_space, pws, r7, pmc_load_exc);
ldwma(s_space, pws, r8, pmc_load_exc);
stwma(d_space, r5, pwd, pmc_store_exc);
stwma(d_space, r6, pwd, pmc_store_exc);
stwma(d_space, r7, pwd, pmc_store_exc);
stwma(d_space, r8, pwd, pmc_store_exc);
len -= 8*sizeof(unsigned int);
}
while (len >= 4*sizeof(unsigned int)) {
register unsigned int r1,r2,r3,r4;
ldwma(s_space, pws, r1, pmc_load_exc);
ldwma(s_space, pws, r2, pmc_load_exc);
ldwma(s_space, pws, r3, pmc_load_exc);
ldwma(s_space, pws, r4, pmc_load_exc);
stwma(d_space, r1, pwd, pmc_store_exc);
stwma(d_space, r2, pwd, pmc_store_exc);
stwma(d_space, r3, pwd, pmc_store_exc);
stwma(d_space, r4, pwd, pmc_store_exc);
len -= 4*sizeof(unsigned int);
}
pcs = (unsigned char *)pws;
pcd = (unsigned char *)pwd;
byte_copy:
while (len) {
/* *pcd++ = *pcs++; */
ldbma(s_space, pcs, t3, pmc_load_exc);
stbma(d_space, t3, pcd, pmc_store_exc);
len--;
}
return 0;
unaligned_copy:
/* possibly we are aligned on a word, but not on a double... */
if (likely(t1 & (sizeof(unsigned int)-1)) == 0) {
t2 = src & (sizeof(unsigned int) - 1);
if (unlikely(t2 != 0)) {
t2 = sizeof(unsigned int) - t2;
while (t2) {
/* *pcd++ = *pcs++; */
ldbma(s_space, pcs, t3, pmc_load_exc);
stbma(d_space, t3, pcd, pmc_store_exc);
len--;
t2--;
}
}
pws = (unsigned int *)pcs;
pwd = (unsigned int *)pcd;
goto word_copy;
}
/* Align the destination. */
if (unlikely((dst & (sizeof(unsigned int) - 1)) != 0)) {
t2 = sizeof(unsigned int) - (dst & (sizeof(unsigned int) - 1));
while (t2) {
/* *pcd++ = *pcs++; */
ldbma(s_space, pcs, t3, pmc_load_exc);
stbma(d_space, t3, pcd, pmc_store_exc);
len--;
t2--;
}
dst = (unsigned long)pcd;
src = (unsigned long)pcs;
}
ret = copy_dstaligned(dst, src, len / sizeof(unsigned int),
o_dst, o_src, o_len);
if (ret)
return ret;
pcs += (len & -sizeof(unsigned int));
pcd += (len & -sizeof(unsigned int));
len %= sizeof(unsigned int);
preserve_branch(handle_load_error);
preserve_branch(handle_store_error);
goto byte_copy;
handle_load_error:
__asm__ __volatile__ ("pmc_load_exc:\n");
d = &__get_cpu_var(exception_data);
DPRINTF("pmc_load_exc: o_len=%lu fault_addr=%lu o_src=%lu ret=%lu\n",
o_len, d->fault_addr, o_src, o_len - d->fault_addr + o_src);
return o_len - d->fault_addr + o_src;
handle_store_error:
__asm__ __volatile__ ("pmc_store_exc:\n");
d = &__get_cpu_var(exception_data);
DPRINTF("pmc_store_exc: o_len=%lu fault_addr=%lu o_dst=%lu ret=%lu\n",
o_len, d->fault_addr, o_dst, o_len - d->fault_addr + o_dst);
return o_len - d->fault_addr + o_dst;
}
#ifdef __KERNEL__
unsigned long copy_to_user(void __user *dst, const void *src, unsigned long len)
{
mtsp(get_kernel_space(), 1);
mtsp(get_user_space(), 2);
return pa_memcpy((void __force *)dst, src, len);
}
unsigned long copy_from_user(void *dst, const void __user *src, unsigned long len)
{
mtsp(get_user_space(), 1);
mtsp(get_kernel_space(), 2);
return pa_memcpy(dst, (void __force *)src, len);
}
unsigned long copy_in_user(void __user *dst, const void __user *src, unsigned long len)
{
mtsp(get_user_space(), 1);
mtsp(get_user_space(), 2);
return pa_memcpy((void __force *)dst, (void __force *)src, len);
}
void * memcpy(void * dst,const void *src, size_t count)
{
mtsp(get_kernel_space(), 1);
mtsp(get_kernel_space(), 2);
pa_memcpy(dst, src, count);
return dst;
}
EXPORT_SYMBOL(copy_to_user);
EXPORT_SYMBOL(copy_from_user);
EXPORT_SYMBOL(copy_in_user);
EXPORT_SYMBOL(memcpy);
#endif
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