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>
128 lines
3.5 KiB
ArmAsm
128 lines
3.5 KiB
ArmAsm
/*
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* Copyright (C) 2013 ARM Ltd.
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* Copyright (C) 2013 Linaro.
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*
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* This code is based on glibc cortex strings work originally authored by Linaro
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* and re-licensed under GPLv2 for the Linux kernel. The original code can
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* be found @
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*
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* http://bazaar.launchpad.net/~linaro-toolchain-dev/cortex-strings/trunk/
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* files/head:/src/aarch64/
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <linux/linkage.h>
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#include <asm/assembler.h>
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/*
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* calculate the length of a string
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*
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* Parameters:
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* x0 - const string pointer
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* Returns:
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* x0 - the return length of specific string
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*/
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/* Arguments and results. */
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srcin .req x0
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len .req x0
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/* Locals and temporaries. */
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src .req x1
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data1 .req x2
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data2 .req x3
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data2a .req x4
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has_nul1 .req x5
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has_nul2 .req x6
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tmp1 .req x7
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tmp2 .req x8
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tmp3 .req x9
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tmp4 .req x10
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zeroones .req x11
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pos .req x12
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#define REP8_01 0x0101010101010101
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#define REP8_7f 0x7f7f7f7f7f7f7f7f
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#define REP8_80 0x8080808080808080
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WEAK(strlen)
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mov zeroones, #REP8_01
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bic src, srcin, #15
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ands tmp1, srcin, #15
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b.ne .Lmisaligned
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/*
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* NUL detection works on the principle that (X - 1) & (~X) & 0x80
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* (=> (X - 1) & ~(X | 0x7f)) is non-zero iff a byte is zero, and
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* can be done in parallel across the entire word.
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*/
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/*
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* The inner loop deals with two Dwords at a time. This has a
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* slightly higher start-up cost, but we should win quite quickly,
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* especially on cores with a high number of issue slots per
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* cycle, as we get much better parallelism out of the operations.
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*/
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.Lloop:
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ldp data1, data2, [src], #16
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.Lrealigned:
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sub tmp1, data1, zeroones
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orr tmp2, data1, #REP8_7f
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sub tmp3, data2, zeroones
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orr tmp4, data2, #REP8_7f
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bic has_nul1, tmp1, tmp2
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bics has_nul2, tmp3, tmp4
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ccmp has_nul1, #0, #0, eq /* NZCV = 0000 */
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b.eq .Lloop
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sub len, src, srcin
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cbz has_nul1, .Lnul_in_data2
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CPU_BE( mov data2, data1 ) /*prepare data to re-calculate the syndrome*/
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sub len, len, #8
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mov has_nul2, has_nul1
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.Lnul_in_data2:
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/*
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* For big-endian, carry propagation (if the final byte in the
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* string is 0x01) means we cannot use has_nul directly. The
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* easiest way to get the correct byte is to byte-swap the data
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* and calculate the syndrome a second time.
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*/
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CPU_BE( rev data2, data2 )
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CPU_BE( sub tmp1, data2, zeroones )
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CPU_BE( orr tmp2, data2, #REP8_7f )
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CPU_BE( bic has_nul2, tmp1, tmp2 )
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sub len, len, #8
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rev has_nul2, has_nul2
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clz pos, has_nul2
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add len, len, pos, lsr #3 /* Bits to bytes. */
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ret
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.Lmisaligned:
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cmp tmp1, #8
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neg tmp1, tmp1
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ldp data1, data2, [src], #16
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lsl tmp1, tmp1, #3 /* Bytes beyond alignment -> bits. */
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mov tmp2, #~0
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/* Big-endian. Early bytes are at MSB. */
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CPU_BE( lsl tmp2, tmp2, tmp1 ) /* Shift (tmp1 & 63). */
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/* Little-endian. Early bytes are at LSB. */
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CPU_LE( lsr tmp2, tmp2, tmp1 ) /* Shift (tmp1 & 63). */
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orr data1, data1, tmp2
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orr data2a, data2, tmp2
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csinv data1, data1, xzr, le
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csel data2, data2, data2a, le
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b .Lrealigned
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ENDPIPROC(strlen)
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EXPORT_SYMBOL_NOKASAN(strlen)
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