ac0e8c72b0
For a while now it's been possible to use EXPORT_SYMBOL() in assembly files, which allows us to place exports immediately after assembly functions, as we do for C functions. As a step towards removing arm64ksyms.c, let's move the string routine exports to the assembly files the functions are defined in. Routines which should only be exported for !KASAN builds are exported using the EXPORT_SYMBOL_NOKASAN() helper. There should be no functional change as a result of this patch. Signed-off-by: Mark Rutland <mark.rutland@arm.com> Cc: Will Deacon <will.deacon@arm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
312 lines
8.8 KiB
ArmAsm
312 lines
8.8 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 two strings
|
|
*
|
|
* Parameters:
|
|
* x0 - const string 1 pointer
|
|
* x1 - const string 2 pointer
|
|
* x2 - the maximal length to be compared
|
|
* Returns:
|
|
* x0 - an integer less than, equal to, or greater than zero if s1 is found,
|
|
* respectively, to be less than, to match, or be greater than s2.
|
|
*/
|
|
|
|
#define REP8_01 0x0101010101010101
|
|
#define REP8_7f 0x7f7f7f7f7f7f7f7f
|
|
#define REP8_80 0x8080808080808080
|
|
|
|
/* 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
|
|
syndrome .req x7
|
|
tmp1 .req x8
|
|
tmp2 .req x9
|
|
tmp3 .req x10
|
|
zeroones .req x11
|
|
pos .req x12
|
|
limit_wd .req x13
|
|
mask .req x14
|
|
endloop .req x15
|
|
|
|
WEAK(strncmp)
|
|
cbz limit, .Lret0
|
|
eor tmp1, src1, src2
|
|
mov zeroones, #REP8_01
|
|
tst tmp1, #7
|
|
b.ne .Lmisaligned8
|
|
ands tmp1, src1, #7
|
|
b.ne .Lmutual_align
|
|
/* Calculate the number of full and partial words -1. */
|
|
/*
|
|
* when limit is mulitply of 8, if not sub 1,
|
|
* the judgement of last dword will wrong.
|
|
*/
|
|
sub limit_wd, limit, #1 /* limit != 0, so no underflow. */
|
|
lsr limit_wd, limit_wd, #3 /* Convert to Dwords. */
|
|
|
|
/*
|
|
* NUL detection works on the principle that (X - 1) & (~X) & 0x80
|
|
* (=> (X - 1) & ~(X | 0x7f)) is non-zero iff a byte is zero, and
|
|
* can be done in parallel across the entire word.
|
|
*/
|
|
.Lloop_aligned:
|
|
ldr data1, [src1], #8
|
|
ldr data2, [src2], #8
|
|
.Lstart_realigned:
|
|
subs limit_wd, limit_wd, #1
|
|
sub tmp1, data1, zeroones
|
|
orr tmp2, data1, #REP8_7f
|
|
eor diff, data1, data2 /* Non-zero if differences found. */
|
|
csinv endloop, diff, xzr, pl /* Last Dword or differences.*/
|
|
bics has_nul, tmp1, tmp2 /* Non-zero if NUL terminator. */
|
|
ccmp endloop, #0, #0, eq
|
|
b.eq .Lloop_aligned
|
|
|
|
/*Not reached the limit, must have found the end or a diff. */
|
|
tbz limit_wd, #63, .Lnot_limit
|
|
|
|
/* Limit % 8 == 0 => all bytes significant. */
|
|
ands limit, limit, #7
|
|
b.eq .Lnot_limit
|
|
|
|
lsl limit, limit, #3 /* Bits -> bytes. */
|
|
mov mask, #~0
|
|
CPU_BE( lsr mask, mask, limit )
|
|
CPU_LE( lsl mask, mask, limit )
|
|
bic data1, data1, mask
|
|
bic data2, data2, mask
|
|
|
|
/* Make sure that the NUL byte is marked in the syndrome. */
|
|
orr has_nul, has_nul, mask
|
|
|
|
.Lnot_limit:
|
|
orr syndrome, diff, has_nul
|
|
b .Lcal_cmpresult
|
|
|
|
.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.
|
|
* We also need to adjust the limit calculations, but without
|
|
* overflowing if the limit is near ULONG_MAX.
|
|
*/
|
|
bic src1, src1, #7
|
|
bic src2, src2, #7
|
|
ldr data1, [src1], #8
|
|
neg tmp3, tmp1, lsl #3 /* 64 - bits(bytes beyond align). */
|
|
ldr data2, [src2], #8
|
|
mov tmp2, #~0
|
|
sub limit_wd, limit, #1 /* limit != 0, so no underflow. */
|
|
/* Big-endian. Early bytes are at MSB. */
|
|
CPU_BE( lsl tmp2, tmp2, tmp3 ) /* Shift (tmp1 & 63). */
|
|
/* Little-endian. Early bytes are at LSB. */
|
|
CPU_LE( lsr tmp2, tmp2, tmp3 ) /* Shift (tmp1 & 63). */
|
|
|
|
and tmp3, limit_wd, #7
|
|
lsr limit_wd, limit_wd, #3
|
|
/* Adjust the limit. Only low 3 bits used, so overflow irrelevant.*/
|
|
add limit, limit, tmp1
|
|
add tmp3, tmp3, tmp1
|
|
orr data1, data1, tmp2
|
|
orr data2, data2, tmp2
|
|
add limit_wd, limit_wd, tmp3, lsr #3
|
|
b .Lstart_realigned
|
|
|
|
/*when src1 offset is not equal to src2 offset...*/
|
|
.Lmisaligned8:
|
|
cmp limit, #8
|
|
b.lo .Ltiny8proc /*limit < 8... */
|
|
/*
|
|
* Get the align offset length to compare per byte first.
|
|
* After this process, one string's address will be aligned.*/
|
|
and tmp1, src1, #7
|
|
neg tmp1, tmp1
|
|
add tmp1, tmp1, #8
|
|
and tmp2, src2, #7
|
|
neg tmp2, tmp2
|
|
add tmp2, tmp2, #8
|
|
subs tmp3, tmp1, tmp2
|
|
csel pos, tmp1, tmp2, hi /*Choose the maximum. */
|
|
/*
|
|
* Here, limit is not less than 8, so directly run .Ltinycmp
|
|
* without checking the limit.*/
|
|
sub limit, limit, pos
|
|
.Ltinycmp:
|
|
ldrb data1w, [src1], #1
|
|
ldrb data2w, [src2], #1
|
|
subs pos, pos, #1
|
|
ccmp data1w, #1, #0, ne /* NZCV = 0b0000. */
|
|
ccmp data1w, data2w, #0, cs /* NZCV = 0b0000. */
|
|
b.eq .Ltinycmp
|
|
cbnz pos, 1f /*find the null or unequal...*/
|
|
cmp data1w, #1
|
|
ccmp data1w, data2w, #0, cs
|
|
b.eq .Lstart_align /*the last bytes are equal....*/
|
|
1:
|
|
sub result, data1, data2
|
|
ret
|
|
|
|
.Lstart_align:
|
|
lsr limit_wd, limit, #3
|
|
cbz limit_wd, .Lremain8
|
|
/*process more leading bytes to make str1 aligned...*/
|
|
ands xzr, src1, #7
|
|
b.eq .Lrecal_offset
|
|
add src1, src1, tmp3 /*tmp3 is positive in this branch.*/
|
|
add src2, src2, tmp3
|
|
ldr data1, [src1], #8
|
|
ldr data2, [src2], #8
|
|
|
|
sub limit, limit, tmp3
|
|
lsr limit_wd, limit, #3
|
|
subs limit_wd, limit_wd, #1
|
|
|
|
sub tmp1, data1, zeroones
|
|
orr tmp2, data1, #REP8_7f
|
|
eor diff, data1, data2 /* Non-zero if differences found. */
|
|
csinv endloop, diff, xzr, ne/*if limit_wd is 0,will finish the cmp*/
|
|
bics has_nul, tmp1, tmp2
|
|
ccmp endloop, #0, #0, eq /*has_null is ZERO: no null byte*/
|
|
b.ne .Lunequal_proc
|
|
/*How far is the current str2 from the alignment boundary...*/
|
|
and tmp3, tmp3, #7
|
|
.Lrecal_offset:
|
|
neg pos, tmp3
|
|
.Lloopcmp_proc:
|
|
/*
|
|
* Divide the eight bytes into two parts. First,backwards the src2
|
|
* to an alignment boundary,load eight bytes from the SRC2 alignment
|
|
* boundary,then compare with the relative bytes from SRC1.
|
|
* 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]
|
|
sub tmp1, data1, zeroones
|
|
orr tmp2, data1, #REP8_7f
|
|
bics has_nul, tmp1, tmp2 /* Non-zero if NUL terminator. */
|
|
eor diff, data1, data2 /* Non-zero if differences found. */
|
|
csinv endloop, diff, xzr, eq
|
|
cbnz endloop, .Lunequal_proc
|
|
|
|
/*The second part process*/
|
|
ldr data1, [src1], #8
|
|
ldr data2, [src2], #8
|
|
subs limit_wd, limit_wd, #1
|
|
sub tmp1, data1, zeroones
|
|
orr tmp2, data1, #REP8_7f
|
|
eor diff, data1, data2 /* Non-zero if differences found. */
|
|
csinv endloop, diff, xzr, ne/*if limit_wd is 0,will finish the cmp*/
|
|
bics has_nul, tmp1, tmp2
|
|
ccmp endloop, #0, #0, eq /*has_null is ZERO: no null byte*/
|
|
b.eq .Lloopcmp_proc
|
|
|
|
.Lunequal_proc:
|
|
orr syndrome, diff, has_nul
|
|
cbz syndrome, .Lremain8
|
|
.Lcal_cmpresult:
|
|
/*
|
|
* reversed the byte-order as big-endian,then CLZ can find the most
|
|
* significant zero bits.
|
|
*/
|
|
CPU_LE( rev syndrome, syndrome )
|
|
CPU_LE( rev data1, data1 )
|
|
CPU_LE( rev data2, data2 )
|
|
/*
|
|
* For big-endian we cannot use the trick with the syndrome value
|
|
* as carry-propagation can corrupt the upper bits if the trailing
|
|
* bytes in the string contain 0x01.
|
|
* However, if there is no NUL byte in the dword, we can generate
|
|
* the result directly. We can't just subtract the bytes as the
|
|
* MSB might be significant.
|
|
*/
|
|
CPU_BE( cbnz has_nul, 1f )
|
|
CPU_BE( cmp data1, data2 )
|
|
CPU_BE( cset result, ne )
|
|
CPU_BE( cneg result, result, lo )
|
|
CPU_BE( ret )
|
|
CPU_BE( 1: )
|
|
/* Re-compute the NUL-byte detection, using a byte-reversed value.*/
|
|
CPU_BE( rev tmp3, data1 )
|
|
CPU_BE( sub tmp1, tmp3, zeroones )
|
|
CPU_BE( orr tmp2, tmp3, #REP8_7f )
|
|
CPU_BE( bic has_nul, tmp1, tmp2 )
|
|
CPU_BE( rev has_nul, has_nul )
|
|
CPU_BE( orr syndrome, diff, has_nul )
|
|
/*
|
|
* The MS-non-zero bit of the syndrome marks either the first bit
|
|
* that is different, or the top bit of the first zero byte.
|
|
* Shifting left now will bring the critical information into the
|
|
* top bits.
|
|
*/
|
|
clz pos, syndrome
|
|
lsl data1, data1, pos
|
|
lsl data2, data2, pos
|
|
/*
|
|
* But we need to zero-extend (char is unsigned) the value and then
|
|
* perform a signed 32-bit subtraction.
|
|
*/
|
|
lsr data1, data1, #56
|
|
sub result, data1, data2, lsr #56
|
|
ret
|
|
|
|
.Lremain8:
|
|
/* Limit % 8 == 0 => all bytes significant. */
|
|
ands limit, limit, #7
|
|
b.eq .Lret0
|
|
.Ltiny8proc:
|
|
ldrb data1w, [src1], #1
|
|
ldrb data2w, [src2], #1
|
|
subs limit, limit, #1
|
|
|
|
ccmp data1w, #1, #0, ne /* NZCV = 0b0000. */
|
|
ccmp data1w, data2w, #0, cs /* NZCV = 0b0000. */
|
|
b.eq .Ltiny8proc
|
|
sub result, data1, data2
|
|
ret
|
|
|
|
.Lret0:
|
|
mov result, #0
|
|
ret
|
|
ENDPIPROC(strncmp)
|
|
EXPORT_SYMBOL_NOKASAN(strncmp)
|