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Subject[PATCH v2] arm64/lib: add accelerated do_csum for arm64
Date
do_csum() in lib/checksum.c is too slow in ARM64,
and we can use assembly and algorithm to accelerate it.

V2: Fix compile warning reported by kbuild test robot <lkp@intel.com>

Signed-off-by: huhai <huhai@kylinos.cn>
---
arch/arm64/include/asm/checksum.h | 3 +
arch/arm64/lib/Makefile | 2 +-
arch/arm64/lib/checksum.c | 145 ++++++++++++++++++++++++++++++
3 files changed, 149 insertions(+), 1 deletion(-)
create mode 100644 arch/arm64/lib/checksum.c

diff --git a/arch/arm64/include/asm/checksum.h b/arch/arm64/include/asm/checksum.h
index 0b6f5a7d4027..0d7b80fb300e 100644
--- a/arch/arm64/include/asm/checksum.h
+++ b/arch/arm64/include/asm/checksum.h
@@ -26,6 +26,9 @@ static inline __sum16 csum_fold(__wsum csum)
}
#define csum_fold csum_fold

+#define do_csum do_csum
+unsigned int do_csum(const unsigned char *buff, unsigned int len);
+
static inline __sum16 ip_fast_csum(const void *iph, unsigned int ihl)
{
__uint128_t tmp;
diff --git a/arch/arm64/lib/Makefile b/arch/arm64/lib/Makefile
index 69ff9887f724..4134730a121b 100644
--- a/arch/arm64/lib/Makefile
+++ b/arch/arm64/lib/Makefile
@@ -1,5 +1,5 @@
# SPDX-License-Identifier: GPL-2.0
-lib-y := clear_user.o delay.o copy_from_user.o \
+lib-y := checksum.o clear_user.o delay.o copy_from_user.o \
copy_to_user.o copy_in_user.o copy_page.o \
clear_page.o memchr.o memcpy.o memmove.o memset.o \
memcmp.o strcmp.o strncmp.o strlen.o strnlen.o \
diff --git a/arch/arm64/lib/checksum.c b/arch/arm64/lib/checksum.c
new file mode 100644
index 000000000000..5df8c6f9a8ac
--- /dev/null
+++ b/arch/arm64/lib/checksum.c
@@ -0,0 +1,145 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Authors: huhai <huhai@kylinos.cn>
+ * Copyright (C) 2019,Tianjin KYLIN Information Technology Co., Ltd.
+ *
+ * This file contains network checksum routines that are better done
+ * in an architecture-specific manner due to speed.
+ *
+ * Acknowledgements:
+ * This file is based on arch/x86/lib/csum-partial_64.c and
+ * arch/alpha/lib/checksum.c, which was written by Thomas Gleixner
+ * and Rick Gorton respectively.
+ */
+
+#include <linux/compiler.h>
+#include <linux/module.h>
+#include <asm/checksum.h>
+
+static inline unsigned short from64to16(unsigned long x)
+{
+ /*
+ * Using extract instructions is a bit more efficient
+ * than the original shift/bitmask version.
+ */
+ union {
+ unsigned long ul;
+ unsigned int ui[2];
+ unsigned short us[4];
+ } in_v, tmp_v, out_v;
+
+ in_v.ul = x;
+ tmp_v.ul = (unsigned long) in_v.ui[0] + (unsigned long) in_v.ui[1];
+
+ /*
+ * Since the bits of tmp_v.sh[3] are going to always be zero,
+ * we don't have to bother to add that in.
+ */
+ out_v.ul = (unsigned long) tmp_v.us[0] + (unsigned long) tmp_v.us[1]
+ + (unsigned long) tmp_v.us[2];
+
+ /* Similarly, out_v.us[2] is always zero for the final add. */
+ return out_v.us[0] + out_v.us[1];
+}
+
+/*
+ * Do a 64-bit checksum on an arbitrary memory area.
+ * Returns a 16bit checksum.
+ */
+unsigned int do_csum(const unsigned char *buff, unsigned len)
+{
+ unsigned odd, count;
+ unsigned long result = 0;
+
+ if (unlikely(len == 0))
+ return result;
+ odd = 1 & (unsigned long) buff;
+ if (odd) {
+ result = *buff << 8;
+ len--;
+ buff++;
+ }
+ count = len >> 1; /* nr of 16-bit words.. */
+ if (count) {
+ if (2 & (unsigned long) buff) {
+ result += *(unsigned short *)buff;
+ count--;
+ len -= 2;
+ buff += 2;
+ }
+ count >>= 1; /* nr of 32-bit words.. */
+ if (count) {
+ unsigned long zero = 0;
+ unsigned count64;
+
+ if (4 & (unsigned long) buff) {
+ result += *(unsigned int *) buff;
+ count--;
+ len -= 4;
+ buff += 4;
+ }
+ count >>= 1; /* nr of 64-bit words.. */
+
+ /* main loop using 64byte blocks */
+ count64 = count >> 3;
+ while (count64) {
+ __asm__ __volatile__(
+ "ldr x3, [%x1, #0]\n"
+ "adds %x0, %x0, x3\n"
+ "ldr x3, [%x1, #8]\n"
+ "adcs %x0, %x0, x3\n"
+ "ldr x3, [%x1, #16]\n"
+ "adcs %x0, %x0, x3\n"
+ "ldr x3, [%x1, #24]\n"
+ "adcs %x0, %x0, x3\n"
+ "ldr x3, [%x1, #32]\n"
+ "adcs %x0, %x0, x3\n"
+ "ldr x3, [%x1, #40]\n"
+ "adcs %x0, %x0, x3\n"
+ "ldr x3, [%x1, #48]\n"
+ "adcs %x0, %x0, x3\n"
+ "ldr x3, [%x1, #56]\n"
+ "adcs %x0, %x0, x3\n"
+ "adcs %x0, %x0, %x2\n"
+ : "=r" (result)
+ : "r" (buff), "r" (zero), "0" (result)
+ : "cc", "memory", "x3");
+
+ buff += 64;
+ count64--;
+ }
+
+ /* last up to 7 8byte blocks */
+ count %= 8;
+
+ while (count) {
+ __asm__ __volatile__(
+ "adds %x0, %x0, %x1\n"
+ "adcs %x0, %x0, %x2\n"
+ : "=r" (result)
+ : "r" (*(unsigned long *)buff), "r" (zero), "0" (result)
+ : "cc", "memory");
+ --count;
+ buff += 8;
+ }
+ result = (result & 0xffffffff) + (result >> 32);
+
+ if (len & 4) {
+ result += *(unsigned int *) buff;
+ buff += 4;
+ }
+ }
+ if (len & 2) {
+ result += *(unsigned short *) buff;
+ buff += 2;
+ }
+ }
+ if (len & 1)
+ result += *buff;
+
+ result = from64to16(result);
+ if (odd)
+ result = ((result >> 8) & 0xff) | ((result & 0xff) << 8);
+
+ return result;
+}
--
2.17.0


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