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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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9ca255bf04
__memcpy_{to,from}io fall back to byte-at-a-time copying if both the
source and destination pointers are not 8-byte aligned. Since one of the
pointers always points at normal memory, this is unnecessary and
detrimental to performance, so only do byte copying until we hit an 8-byte
boundary for the device pointer.
This change was motivated by performance issues in the pstore driver.
On a test platform, measuring probe time for pstore, console buffer
size of 1/4MB and pmsg of 1/2MB, was in the 90-107ms region. Change
managed to reduce it to 10-25ms, an improvement in boot time.
Cc: Kees Cook <keescook@chromium.org>
Cc: Anton Vorontsov <anton@enomsg.org>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Anton Vorontsov <anton@enomsg.org>
Cc: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Mark Salyzyn <salyzyn@android.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
109 lines
2.1 KiB
C
109 lines
2.1 KiB
C
/*
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* Based on arch/arm/kernel/io.c
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*
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* Copyright (C) 2012 ARM Ltd.
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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/export.h>
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#include <linux/types.h>
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#include <linux/io.h>
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/*
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* Copy data from IO memory space to "real" memory space.
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*/
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void __memcpy_fromio(void *to, const volatile void __iomem *from, size_t count)
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{
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while (count && !IS_ALIGNED((unsigned long)from, 8)) {
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*(u8 *)to = __raw_readb(from);
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from++;
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to++;
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count--;
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}
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while (count >= 8) {
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*(u64 *)to = __raw_readq(from);
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from += 8;
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to += 8;
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count -= 8;
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}
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while (count) {
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*(u8 *)to = __raw_readb(from);
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from++;
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to++;
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count--;
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}
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}
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EXPORT_SYMBOL(__memcpy_fromio);
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/*
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* Copy data from "real" memory space to IO memory space.
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*/
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void __memcpy_toio(volatile void __iomem *to, const void *from, size_t count)
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{
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while (count && !IS_ALIGNED((unsigned long)to, 8)) {
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__raw_writeb(*(u8 *)from, to);
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from++;
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to++;
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count--;
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}
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while (count >= 8) {
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__raw_writeq(*(u64 *)from, to);
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from += 8;
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to += 8;
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count -= 8;
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}
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while (count) {
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__raw_writeb(*(u8 *)from, to);
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from++;
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to++;
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count--;
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}
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}
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EXPORT_SYMBOL(__memcpy_toio);
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/*
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* "memset" on IO memory space.
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*/
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void __memset_io(volatile void __iomem *dst, int c, size_t count)
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{
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u64 qc = (u8)c;
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qc |= qc << 8;
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qc |= qc << 16;
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qc |= qc << 32;
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while (count && !IS_ALIGNED((unsigned long)dst, 8)) {
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__raw_writeb(c, dst);
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dst++;
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count--;
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}
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while (count >= 8) {
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__raw_writeq(qc, dst);
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dst += 8;
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count -= 8;
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}
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while (count) {
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__raw_writeb(c, dst);
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dst++;
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count--;
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}
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}
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EXPORT_SYMBOL(__memset_io);
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