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 0000000000..c9dae65ac0
--- /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 __wsum csum_finalize_sum(u64 temp64)
+{
+	return (__force __wsum)((temp64 + ror64(temp64, 32)) >> 32);
+}
+
+static inline unsigned long update_csum_40b(unsigned long sum, const unsigned long m[5])
+{
+	asm("addq %1,%0\n\t"
+	     "adcq %2,%0\n\t"
+	     "adcq %3,%0\n\t"
+	     "adcq %4,%0\n\t"
+	     "adcq %5,%0\n\t"
+	     "adcq $0,%0"
+		:"+r" (sum)
+		:"m" (m[0]), "m" (m[1]), "m" (m[2]),
+		 "m" (m[3]), "m" (m[4]));
+	return sum;
+}
+
+/*
+ * 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;
+
+	/* Do two 40-byte chunks in parallel to get better ILP */
+	if (likely(len >= 80)) {
+		u64 temp64_2 = 0;
+		do {
+			temp64 = update_csum_40b(temp64, buff);
+			temp64_2 = update_csum_40b(temp64_2, buff + 40);
+			buff += 80;
+			len -= 80;
+		} while (len >= 80);
+
+		asm("addq %1,%0\n\t"
+		    "adcq $0,%0"
+		    :"+r" (temp64): "r" (temp64_2));
+	}
+
+	/*
+	 * len == 40 is the hot case due to IPv6 headers, so return
+	 * early for that exact case without checking the tail bytes.
+	 */
+	if (len >= 40) {
+		temp64 = update_csum_40b(temp64, buff);
+		len -= 40;
+		if (!len)
+			return csum_finalize_sum(temp64);
+		buff += 40;
+	}
+
+	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), "m"(*(const char(*)[32])buff));
+		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), "m"(*(const char(*)[16])buff));
+		buff += 16;
+	}
+	if (len & 8) {
+		asm("addq 0*8(%[src]),%[res]\n\t"
+		    "adcq $0,%[res]"
+		    : [res] "+r"(temp64)
+		    : [src] "r"(buff), "m"(*(const char(*)[8])buff));
+		buff += 8;
+	}
+	if (len & 7) {
+		unsigned int shift = (-len << 3) & 63;
+		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));
+	}
+	return csum_finalize_sum(temp64);
+}
+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);