mirror of
https://github.com/edk2-porting/linux-next.git
synced 2024-12-27 06:34:11 +08:00
ef769e3208
Signed-off-by: Adam Buchbinder <adam.buchbinder@gmail.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
259 lines
7.0 KiB
ArmAsm
259 lines
7.0 KiB
ArmAsm
/*
|
|
* Copyright (C) 2013 ARM Ltd.
|
|
* Copyright (C) 2013 Linaro.
|
|
*
|
|
* This code is based on glibc cortex strings work originally authored by Linaro
|
|
* and re-licensed under GPLv2 for the Linux kernel. The original code can
|
|
* be found @
|
|
*
|
|
* http://bazaar.launchpad.net/~linaro-toolchain-dev/cortex-strings/trunk/
|
|
* files/head:/src/aarch64/
|
|
*
|
|
* This program is free software; you can redistribute it and/or modify
|
|
* it under the terms of the GNU General Public License version 2 as
|
|
* published by the Free Software Foundation.
|
|
*
|
|
* 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, see <http://www.gnu.org/licenses/>.
|
|
*/
|
|
|
|
#include <linux/linkage.h>
|
|
#include <asm/assembler.h>
|
|
|
|
/*
|
|
* compare memory areas(when two memory areas' offset are different,
|
|
* alignment handled by the hardware)
|
|
*
|
|
* Parameters:
|
|
* x0 - const memory area 1 pointer
|
|
* x1 - const memory area 2 pointer
|
|
* x2 - the maximal compare byte length
|
|
* Returns:
|
|
* x0 - a compare result, maybe less than, equal to, or greater than ZERO
|
|
*/
|
|
|
|
/* Parameters and result. */
|
|
src1 .req x0
|
|
src2 .req x1
|
|
limit .req x2
|
|
result .req x0
|
|
|
|
/* Internal variables. */
|
|
data1 .req x3
|
|
data1w .req w3
|
|
data2 .req x4
|
|
data2w .req w4
|
|
has_nul .req x5
|
|
diff .req x6
|
|
endloop .req x7
|
|
tmp1 .req x8
|
|
tmp2 .req x9
|
|
tmp3 .req x10
|
|
pos .req x11
|
|
limit_wd .req x12
|
|
mask .req x13
|
|
|
|
ENTRY(memcmp)
|
|
cbz limit, .Lret0
|
|
eor tmp1, src1, src2
|
|
tst tmp1, #7
|
|
b.ne .Lmisaligned8
|
|
ands tmp1, src1, #7
|
|
b.ne .Lmutual_align
|
|
sub limit_wd, limit, #1 /* limit != 0, so no underflow. */
|
|
lsr limit_wd, limit_wd, #3 /* Convert to Dwords. */
|
|
/*
|
|
* The input source addresses are at alignment boundary.
|
|
* Directly compare eight bytes each time.
|
|
*/
|
|
.Lloop_aligned:
|
|
ldr data1, [src1], #8
|
|
ldr data2, [src2], #8
|
|
.Lstart_realigned:
|
|
subs limit_wd, limit_wd, #1
|
|
eor diff, data1, data2 /* Non-zero if differences found. */
|
|
csinv endloop, diff, xzr, cs /* Last Dword or differences. */
|
|
cbz endloop, .Lloop_aligned
|
|
|
|
/* Not reached the limit, must have found a diff. */
|
|
tbz limit_wd, #63, .Lnot_limit
|
|
|
|
/* Limit % 8 == 0 => the diff is in the last 8 bytes. */
|
|
ands limit, limit, #7
|
|
b.eq .Lnot_limit
|
|
/*
|
|
* The remained bytes less than 8. It is needed to extract valid data
|
|
* from last eight bytes of the intended memory range.
|
|
*/
|
|
lsl limit, limit, #3 /* bytes-> bits. */
|
|
mov mask, #~0
|
|
CPU_BE( lsr mask, mask, limit )
|
|
CPU_LE( lsl mask, mask, limit )
|
|
bic data1, data1, mask
|
|
bic data2, data2, mask
|
|
|
|
orr diff, diff, mask
|
|
b .Lnot_limit
|
|
|
|
.Lmutual_align:
|
|
/*
|
|
* Sources are mutually aligned, but are not currently at an
|
|
* alignment boundary. Round down the addresses and then mask off
|
|
* the bytes that precede the start point.
|
|
*/
|
|
bic src1, src1, #7
|
|
bic src2, src2, #7
|
|
ldr data1, [src1], #8
|
|
ldr data2, [src2], #8
|
|
/*
|
|
* We can not add limit with alignment offset(tmp1) here. Since the
|
|
* addition probably make the limit overflown.
|
|
*/
|
|
sub limit_wd, limit, #1/*limit != 0, so no underflow.*/
|
|
and tmp3, limit_wd, #7
|
|
lsr limit_wd, limit_wd, #3
|
|
add tmp3, tmp3, tmp1
|
|
add limit_wd, limit_wd, tmp3, lsr #3
|
|
add limit, limit, tmp1/* Adjust the limit for the extra. */
|
|
|
|
lsl tmp1, tmp1, #3/* Bytes beyond alignment -> bits.*/
|
|
neg tmp1, tmp1/* Bits to alignment -64. */
|
|
mov tmp2, #~0
|
|
/*mask off the non-intended bytes before the start address.*/
|
|
CPU_BE( lsl tmp2, tmp2, tmp1 )/*Big-endian.Early bytes are at MSB*/
|
|
/* Little-endian. Early bytes are at LSB. */
|
|
CPU_LE( lsr tmp2, tmp2, tmp1 )
|
|
|
|
orr data1, data1, tmp2
|
|
orr data2, data2, tmp2
|
|
b .Lstart_realigned
|
|
|
|
/*src1 and src2 have different alignment offset.*/
|
|
.Lmisaligned8:
|
|
cmp limit, #8
|
|
b.lo .Ltiny8proc /*limit < 8: compare byte by byte*/
|
|
|
|
and tmp1, src1, #7
|
|
neg tmp1, tmp1
|
|
add tmp1, tmp1, #8/*valid length in the first 8 bytes of src1*/
|
|
and tmp2, src2, #7
|
|
neg tmp2, tmp2
|
|
add tmp2, tmp2, #8/*valid length in the first 8 bytes of src2*/
|
|
subs tmp3, tmp1, tmp2
|
|
csel pos, tmp1, tmp2, hi /*Choose the maximum.*/
|
|
|
|
sub limit, limit, pos
|
|
/*compare the proceeding bytes in the first 8 byte segment.*/
|
|
.Ltinycmp:
|
|
ldrb data1w, [src1], #1
|
|
ldrb data2w, [src2], #1
|
|
subs pos, pos, #1
|
|
ccmp data1w, data2w, #0, ne /* NZCV = 0b0000. */
|
|
b.eq .Ltinycmp
|
|
cbnz pos, 1f /*diff occurred before the last byte.*/
|
|
cmp data1w, data2w
|
|
b.eq .Lstart_align
|
|
1:
|
|
sub result, data1, data2
|
|
ret
|
|
|
|
.Lstart_align:
|
|
lsr limit_wd, limit, #3
|
|
cbz limit_wd, .Lremain8
|
|
|
|
ands xzr, src1, #7
|
|
b.eq .Lrecal_offset
|
|
/*process more leading bytes to make src1 aligned...*/
|
|
add src1, src1, tmp3 /*backwards src1 to alignment boundary*/
|
|
add src2, src2, tmp3
|
|
sub limit, limit, tmp3
|
|
lsr limit_wd, limit, #3
|
|
cbz limit_wd, .Lremain8
|
|
/*load 8 bytes from aligned SRC1..*/
|
|
ldr data1, [src1], #8
|
|
ldr data2, [src2], #8
|
|
|
|
subs limit_wd, limit_wd, #1
|
|
eor diff, data1, data2 /*Non-zero if differences found.*/
|
|
csinv endloop, diff, xzr, ne
|
|
cbnz endloop, .Lunequal_proc
|
|
/*How far is the current SRC2 from the alignment boundary...*/
|
|
and tmp3, tmp3, #7
|
|
|
|
.Lrecal_offset:/*src1 is aligned now..*/
|
|
neg pos, tmp3
|
|
.Lloopcmp_proc:
|
|
/*
|
|
* Divide the eight bytes into two parts. First,backwards the src2
|
|
* to an alignment boundary,load eight bytes and compare from
|
|
* the SRC2 alignment boundary. If all 8 bytes are equal,then start
|
|
* the second part's comparison. Otherwise finish the comparison.
|
|
* This special handle can garantee all the accesses are in the
|
|
* thread/task space in avoid to overrange access.
|
|
*/
|
|
ldr data1, [src1,pos]
|
|
ldr data2, [src2,pos]
|
|
eor diff, data1, data2 /* Non-zero if differences found. */
|
|
cbnz diff, .Lnot_limit
|
|
|
|
/*The second part process*/
|
|
ldr data1, [src1], #8
|
|
ldr data2, [src2], #8
|
|
eor diff, data1, data2 /* Non-zero if differences found. */
|
|
subs limit_wd, limit_wd, #1
|
|
csinv endloop, diff, xzr, ne/*if limit_wd is 0,will finish the cmp*/
|
|
cbz endloop, .Lloopcmp_proc
|
|
.Lunequal_proc:
|
|
cbz diff, .Lremain8
|
|
|
|
/* There is difference occurred in the latest comparison. */
|
|
.Lnot_limit:
|
|
/*
|
|
* For little endian,reverse the low significant equal bits into MSB,then
|
|
* following CLZ can find how many equal bits exist.
|
|
*/
|
|
CPU_LE( rev diff, diff )
|
|
CPU_LE( rev data1, data1 )
|
|
CPU_LE( rev data2, data2 )
|
|
|
|
/*
|
|
* The MS-non-zero bit of DIFF marks either the first bit
|
|
* that is different, or the end of the significant data.
|
|
* Shifting left now will bring the critical information into the
|
|
* top bits.
|
|
*/
|
|
clz pos, diff
|
|
lsl data1, data1, pos
|
|
lsl data2, data2, pos
|
|
/*
|
|
* We need to zero-extend (char is unsigned) the value and then
|
|
* perform a signed subtraction.
|
|
*/
|
|
lsr data1, data1, #56
|
|
sub result, data1, data2, lsr #56
|
|
ret
|
|
|
|
.Lremain8:
|
|
/* Limit % 8 == 0 =>. all data are equal.*/
|
|
ands limit, limit, #7
|
|
b.eq .Lret0
|
|
|
|
.Ltiny8proc:
|
|
ldrb data1w, [src1], #1
|
|
ldrb data2w, [src2], #1
|
|
subs limit, limit, #1
|
|
|
|
ccmp data1w, data2w, #0, ne /* NZCV = 0b0000. */
|
|
b.eq .Ltiny8proc
|
|
sub result, data1, data2
|
|
ret
|
|
.Lret0:
|
|
mov result, #0
|
|
ret
|
|
ENDPIPROC(memcmp)
|