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Message-Id: <1418085538-25877-1-git-send-email-fkan@apm.com> Date: Mon, 8 Dec 2014 16:38:58 -0800 From: Feng Kan <fkan@....com> To: patches@....com, linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org, philipp.tomsich@...obroma-systems.com, dann.frazier@...onical.com, tim.gardner@...onical.com, craig.magina@...onical.com Cc: Feng Kan <fkan@....com> Subject: [PATCH V2] arm64: optimized copy_to_user and copy_from_user assembly code Using the glibc cortex string work work authored by Linaro as base to create new copy to/from user kernel routine. Iperf performance increase: -l (size) 1 core result Optimized 64B 44-51Mb/s 1500B 4.9Gb/s 30000B 16.2Gb/s Original 64B 34-50.7Mb/s 1500B 4.7Gb/s 30000B 14.5Gb/s Signed-off-by: Feng Kan <fkan@....com> --- V2 Changes: 1. move abort handler out to copy_to/from_user source file. 2. fix bug 1400349 reported by Ubuntu. Bug causes by incorrect handling of the copy_to_user abort handler zeroing out dst buffer. https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1400349 The crash was reproduce in immediately with stress test (combination of specweb, fio, iperf). After new patch, the test ran 50 hours without observing the failure. arch/arm64/lib/copy_from_user.S | 87 +++++++++++------ arch/arm64/lib/copy_template.S | 212 ++++++++++++++++++++++++++++++++++++++++ arch/arm64/lib/copy_to_user.S | 57 ++++++----- 3 files changed, 297 insertions(+), 59 deletions(-) create mode 100644 arch/arm64/lib/copy_template.S diff --git a/arch/arm64/lib/copy_from_user.S b/arch/arm64/lib/copy_from_user.S index 5e27add..ca96971 100644 --- a/arch/arm64/lib/copy_from_user.S +++ b/arch/arm64/lib/copy_from_user.S @@ -15,7 +15,6 @@ */ #include <linux/linkage.h> -#include <asm/assembler.h> /* * Copy from user space to a kernel buffer (alignment handled by the hardware) @@ -28,39 +27,63 @@ * x0 - bytes not copied */ ENTRY(__copy_from_user) - add x4, x1, x2 // upper user buffer boundary - subs x2, x2, #8 - b.mi 2f -1: -USER(9f, ldr x3, [x1], #8 ) - subs x2, x2, #8 - str x3, [x0], #8 - b.pl 1b -2: adds x2, x2, #4 - b.mi 3f -USER(9f, ldr w3, [x1], #4 ) - sub x2, x2, #4 - str w3, [x0], #4 -3: adds x2, x2, #2 - b.mi 4f -USER(9f, ldrh w3, [x1], #2 ) - sub x2, x2, #2 - strh w3, [x0], #2 -4: adds x2, x2, #1 - b.mi 5f -USER(9f, ldrb w3, [x1] ) - strb w3, [x0] -5: mov x0, #0 - ret +#include "copy_template.S" ENDPROC(__copy_from_user) .section .fixup,"ax" - .align 2 -9: sub x2, x4, x1 - mov x3, x2 -10: strb wzr, [x0], #1 // zero remaining buffer space - subs x3, x3, #1 - b.ne 10b - mov x0, x2 // bytes not copied + .align 2 +8: + /* + * Count bytes remain + * dst points to (dst + tmp1) + */ + mov x0, count + sub dst, dst, tmp1 + b .Lfinalize +9: + /* + * 16 bytes remain + * dst is accurate + */ + mov x0, #16 + b .Lfinalize +10: + /* + * count is accurate + * dst is accurate + */ + mov x0, count + b .Lfinalize +11: + /* + *(count + tmp2) bytes remain + * dst points to the start of the remaining bytes + */ + add x0, count, tmp2 + b .Lfinalize +12: + /* + * (count + 128) bytes remain + * dst is accurate + */ + add x0, count, #128 + b .Lfinalize +13: + /* + * (count + 128) bytes remain + * dst is pre-biased to (dst + 16) + */ + add x0, count, #128 + add dst, dst, #16 +.Lfinalize: + /* + * Zeroize remaining destination-buffer + */ + mov count, x0 +20: + /* Zero remaining buffer space */ + strb wzr, [dst], #1 + subs count, count, #1 + b.ne 20b ret .previous diff --git a/arch/arm64/lib/copy_template.S b/arch/arm64/lib/copy_template.S new file mode 100644 index 0000000..c07eea6 --- /dev/null +++ b/arch/arm64/lib/copy_template.S @@ -0,0 +1,212 @@ +/* + * Copyright (c) 2013, Applied Micro Circuits Corporation + * Copyright (c) 2012-2013, Linaro Limited + * + * Author: Feng Kan <fkan@....com> + * Author: Philipp Tomsich <philipp.tomsich@...obroma-systems.com> + * + * The code is adopted from the memcpy routine by Linaro Limited. + * + * This file is free software: you may copy, redistribute and/or modify it + * under the terms of the GNU General Public License as published by the + * Free Software Foundation, either version 2 of the License, or (at your + * option) any later version. + * + * This file 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/>. + * + * This file incorporates work covered by the following copyright and + * permission notice: + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions are met: + * 1 Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2 Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * 3 Neither the name of the Linaro nor the + * names of its contributors may be used to endorse or promote products + * derived from this software without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS + * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT + * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR + * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT + * HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, + * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT + * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, + * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY + * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE + * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + */ +#include <asm/assembler.h> + +dstin .req x0 +src .req x1 +count .req x2 +tmp1 .req x3 +tmp1w .req w3 +tmp2 .req x4 +tmp2w .req w4 +tmp3 .req x5 +tmp3w .req w5 +dst .req x6 + +A_l .req x7 +A_h .req x8 +B_l .req x9 +B_h .req x10 +C_l .req x11 +C_h .req x12 +D_l .req x13 +D_h .req x14 + + mov dst, dstin + cmp count, #64 + b.ge .Lcpy_not_short + cmp count, #15 + b.le .Ltail15tiny + + /* + * Deal with small copies quickly by dropping straight into the + * exit block. + */ +.Ltail63: + /* + * Copy up to 48 bytes of data. At this point we only need the + * bottom 6 bits of count to be accurate. + */ + ands tmp1, count, #0x30 + b.eq .Ltail15 + add dst, dst, tmp1 + add src, src, tmp1 + cmp tmp1w, #0x20 + b.eq 1f + b.lt 2f + USER(8f, ldp A_l, A_h, [src, #-48]) + USER(8f, stp A_l, A_h, [dst, #-48]) +1: + USER(8f, ldp A_l, A_h, [src, #-32]) + USER(8f, stp A_l, A_h, [dst, #-32]) +2: + USER(8f, ldp A_l, A_h, [src, #-16]) + USER(8f, stp A_l, A_h, [dst, #-16]) + +.Ltail15: + ands count, count, #15 + beq 1f + add src, src, count + USER(9f, ldp A_l, A_h, [src, #-16]) + add dst, dst, count + USER(9f, stp A_l, A_h, [dst, #-16]) +1: + b .Lsuccess + +.Ltail15tiny: + /* + * Copy up to 15 bytes of data. Does not assume additional data + * being copied. + */ + tbz count, #3, 1f + USER(10f, ldr tmp1, [src], #8) + USER(10f, str tmp1, [dst], #8) +1: + tbz count, #2, 1f + USER(10f, ldr tmp1w, [src], #4) + USER(10f, str tmp1w, [dst], #4) +1: + tbz count, #1, 1f + USER(10f, ldrh tmp1w, [src], #2) + USER(10f, strh tmp1w, [dst], #2) +1: + tbz count, #0, 1f + USER(10f, ldrb tmp1w, [src]) + USER(10f, strb tmp1w, [dst]) +1: + b .Lsuccess + +.Lcpy_not_short: + /* + * We don't much care about the alignment of DST, but we want SRC + * to be 128-bit (16 byte) aligned so that we don't cross cache line + * boundaries on both loads and stores. + */ + neg tmp2, src + ands tmp2, tmp2, #15 /* Bytes to reach alignment. */ + b.eq 2f + sub count, count, tmp2 + /* + * Copy more data than needed; it's faster than jumping + * around copying sub-Quadword quantities. We know that + * it can't overrun. + */ + USER(11f, ldp A_l, A_h, [src]) + add src, src, tmp2 + USER(11f, stp A_l, A_h, [dst]) + add dst, dst, tmp2 + /* There may be less than 63 bytes to go now. */ + cmp count, #63 + b.le .Ltail63 +2: + subs count, count, #128 + b.ge .Lcpy_body_large + /* + * Less than 128 bytes to copy, so handle 64 here and then jump + * to the tail. + */ + USER(12f, ldp A_l, A_h, [src]) + USER(12f, ldp B_l, B_h, [src, #16]) + USER(12f, ldp C_l, C_h, [src, #32]) + USER(12f, ldp D_l, D_h, [src, #48]) + USER(12f, stp A_l, A_h, [dst]) + USER(12f, stp B_l, B_h, [dst, #16]) + USER(12f, stp C_l, C_h, [dst, #32]) + USER(12f, stp D_l, D_h, [dst, #48]) + tst count, #0x3f + add src, src, #64 + add dst, dst, #64 + b.ne .Ltail63 + b .Lsuccess + + /* + * Critical loop. Start at a new cache line boundary. Assuming + * 64 bytes per line this ensures the entire loop is in one line. + */ + .p2align 6 +.Lcpy_body_large: + /* There are at least 128 bytes to copy. */ + USER(12f, ldp A_l, A_h, [src, #0]) + sub dst, dst, #16 /* Pre-bias. */ + USER(13f, ldp B_l, B_h, [src, #16]) + USER(13f, ldp C_l, C_h, [src, #32]) + USER(13f, ldp D_l, D_h, [src, #48]!) /* src += 64 - Pre-bias. */ +1: + USER(13f, stp A_l, A_h, [dst, #16]) + USER(13f, ldp A_l, A_h, [src, #16]) + USER(13f, stp B_l, B_h, [dst, #32]) + USER(13f, ldp B_l, B_h, [src, #32]) + USER(13f, stp C_l, C_h, [dst, #48]) + USER(13f, ldp C_l, C_h, [src, #48]) + USER(13f, stp D_l, D_h, [dst, #64]!) + USER(13f, ldp D_l, D_h, [src, #64]!) + subs count, count, #64 + b.ge 1b + USER(13f, stp A_l, A_h, [dst, #16]) + USER(13f, stp B_l, B_h, [dst, #32]) + USER(13f, stp C_l, C_h, [dst, #48]) + USER(13f, stp D_l, D_h, [dst, #64]) + add src, src, #16 + add dst, dst, #64 + 16 + tst count, #0x3f + b.ne .Ltail63 +.Lsuccess: + /* Nothing left to copy */ + mov x0, #0 + ret diff --git a/arch/arm64/lib/copy_to_user.S b/arch/arm64/lib/copy_to_user.S index a0aeeb9..af24bfa 100644 --- a/arch/arm64/lib/copy_to_user.S +++ b/arch/arm64/lib/copy_to_user.S @@ -15,7 +15,6 @@ */ #include <linux/linkage.h> -#include <asm/assembler.h> /* * Copy to user space from a kernel buffer (alignment handled by the hardware) @@ -28,34 +27,38 @@ * x0 - bytes not copied */ ENTRY(__copy_to_user) - add x4, x0, x2 // upper user buffer boundary - subs x2, x2, #8 - b.mi 2f -1: - ldr x3, [x1], #8 - subs x2, x2, #8 -USER(9f, str x3, [x0], #8 ) - b.pl 1b -2: adds x2, x2, #4 - b.mi 3f - ldr w3, [x1], #4 - sub x2, x2, #4 -USER(9f, str w3, [x0], #4 ) -3: adds x2, x2, #2 - b.mi 4f - ldrh w3, [x1], #2 - sub x2, x2, #2 -USER(9f, strh w3, [x0], #2 ) -4: adds x2, x2, #1 - b.mi 5f - ldrb w3, [x1] -USER(9f, strb w3, [x0] ) -5: mov x0, #0 - ret +#include "copy_template.S" ENDPROC(__copy_to_user) .section .fixup,"ax" - .align 2 -9: sub x0, x4, x0 // bytes not copied + .align 2 +8: +10: + /* + * count is accurate + */ + mov x0, count + b .Lfinalize +9: + /* + * 16 bytes remain + */ + mov x0, #16 + b .Lfinalize +11: + /* + *(count + tmp2) bytes remain + * dst points to the start of the remaining bytes + */ + add x0, count, tmp2 + b .Lfinalize +12: +13: + /* + * (count + 128) bytes remain + */ + add x0, count, #128 + b .Lfinalize +.Lfinalize: ret .previous -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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