1 files changed, 123 insertions, 0 deletions
diff --git a/arch/x86/lib/csum-partial_64.c b/arch/x86/lib/csum-partial_64.c
new file mode 100644
index 000000000..50734a230
--- /dev/null
+++ b/arch/x86/lib/csum-partial_64.c
@@ -0,0 +1,123 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * arch/x86_64/lib/csum-partial.c
+ *
+ * This file contains network checksum routines that are better done
+ * in an architecture-specific manner due to speed.
+ */
+ 
+#include <linux/compiler.h>
+#include <linux/export.h>
+#include <asm/checksum.h>
+#include <asm/word-at-a-time.h>
+
+static inline unsigned short from32to16(unsigned a) 
+{
+	unsigned short b = a >> 16; 
+	asm("addw %w2,%w0\n\t"
+	    "adcw $0,%w0\n" 
+	    : "=r" (b)
+	    : "0" (b), "r" (a));
+	return b;
+}
+
+/*
+ * Do a checksum on an arbitrary memory area.
+ * Returns a 32bit checksum.
+ *
+ * This isn't as time critical as it used to be because many NICs
+ * do hardware checksumming these days.
+ *
+ * Still, with CHECKSUM_COMPLETE this is called to compute
+ * checksums on IPv6 headers (40 bytes) and other small parts.
+ * it's best to have buff aligned on a 64-bit boundary
+ */
+__wsum csum_partial(const void *buff, int len, __wsum sum)
+{
+	u64 temp64 = (__force u64)sum;
+	unsigned odd, result;
+
+	odd = 1 & (unsigned long) buff;
+	if (unlikely(odd)) {
+		if (unlikely(len == 0))
+			return sum;
+		temp64 = ror32((__force u32)sum, 8);
+		temp64 += (*(unsigned char *)buff << 8);
+		len--;
+		buff++;
+	}
+
+	while (unlikely(len >= 64)) {
+		asm("addq 0*8(%[src]),%[res]\n\t"
+		    "adcq 1*8(%[src]),%[res]\n\t"
+		    "adcq 2*8(%[src]),%[res]\n\t"
+		    "adcq 3*8(%[src]),%[res]\n\t"
+		    "adcq 4*8(%[src]),%[res]\n\t"
+		    "adcq 5*8(%[src]),%[res]\n\t"
+		    "adcq 6*8(%[src]),%[res]\n\t"
+		    "adcq 7*8(%[src]),%[res]\n\t"
+		    "adcq $0,%[res]"
+		    : [res] "+r" (temp64)
+		    : [src] "r" (buff)
+		    : "memory");
+		buff += 64;
+		len -= 64;
+	}
+
+	if (len & 32) {
+		asm("addq 0*8(%[src]),%[res]\n\t"
+		    "adcq 1*8(%[src]),%[res]\n\t"
+		    "adcq 2*8(%[src]),%[res]\n\t"
+		    "adcq 3*8(%[src]),%[res]\n\t"
+		    "adcq $0,%[res]"
+			: [res] "+r" (temp64)
+			: [src] "r" (buff)
+			: "memory");
+		buff += 32;
+	}
+	if (len & 16) {
+		asm("addq 0*8(%[src]),%[res]\n\t"
+		    "adcq 1*8(%[src]),%[res]\n\t"
+		    "adcq $0,%[res]"
+			: [res] "+r" (temp64)
+			: [src] "r" (buff)
+			: "memory");
+		buff += 16;
+	}
+	if (len & 8) {
+		asm("addq 0*8(%[src]),%[res]\n\t"
+		    "adcq $0,%[res]"
+			: [res] "+r" (temp64)
+			: [src] "r" (buff)
+			: "memory");
+		buff += 8;
+	}
+	if (len & 7) {
+		unsigned int shift = (8 - (len & 7)) * 8;
+		unsigned long trail;
+
+		trail = (load_unaligned_zeropad(buff) << shift) >> shift;
+
+		asm("addq %[trail],%[res]\n\t"
+		    "adcq $0,%[res]"
+			: [res] "+r" (temp64)
+			: [trail] "r" (trail));
+	}
+	result = add32_with_carry(temp64 >> 32, temp64 & 0xffffffff);
+	if (unlikely(odd)) {
+		result = from32to16(result);
+		result = ((result >> 8) & 0xff) | ((result & 0xff) << 8);
+	}
+	return (__force __wsum)result;
+}
+EXPORT_SYMBOL(csum_partial);
+
+/*
+ * this routine is used for miscellaneous IP-like checksums, mainly
+ * in icmp.c
+ */
+__sum16 ip_compute_csum(const void *buff, int len)
+{
+	return csum_fold(csum_partial(buff,len,0));
+}
+EXPORT_SYMBOL(ip_compute_csum);