LoongArch: Add SIMD-optimized XOR routines

Add LSX and LASX implementations of xor operations, operating on 64
bytes (one L1 cache line) at a time, for a balance between memory
utilization and instruction mix. Huacai confirmed that all future
LoongArch implementations by Loongson (that we care) will likely also
feature 64-byte cache lines, and experiments show no throughput
improvement with further unrolling.

Performance numbers measured during system boot on a 3A5000 @ 2.5GHz:

> 8regs           : 12702 MB/sec
> 8regs_prefetch  : 10920 MB/sec
> 32regs          : 12686 MB/sec
> 32regs_prefetch : 10918 MB/sec
> lsx             : 17589 MB/sec
> lasx            : 26116 MB/sec

Acked-by: Song Liu <song@kernel.org>
Signed-off-by: WANG Xuerui <git@xen0n.name>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>

1 files changed, 110 insertions, 0 deletions

diff --git a/arch/loongarch/lib/xor_template.c b/arch/loongarch/lib/xor_template.c
new file mode 100644
index 000000000000..0358ced7fe33
--- /dev/null
+++ b/arch/loongarch/lib/xor_template.c
@@ -0,0 +1,110 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2023 WANG Xuerui <git@xen0n.name>
+ *
+ * Template for XOR operations, instantiated in xor_simd.c.
+ *
+ * Expected preprocessor definitions:
+ *
+ * - LINE_WIDTH
+ * - XOR_FUNC_NAME(nr)
+ * - LD_INOUT_LINE(buf)
+ * - LD_AND_XOR_LINE(buf)
+ * - ST_LINE(buf)
+ */
+
+void XOR_FUNC_NAME(2)(unsigned long bytes,
+		      unsigned long * __restrict v1,
+		      const unsigned long * __restrict v2)
+{
+	unsigned long lines = bytes / LINE_WIDTH;
+
+	do {
+		__asm__ __volatile__ (
+			LD_INOUT_LINE(v1)
+			LD_AND_XOR_LINE(v2)
+			ST_LINE(v1)
+		: : [v1] "r"(v1), [v2] "r"(v2) : "memory"
+		);
+
+		v1 += LINE_WIDTH / sizeof(unsigned long);
+		v2 += LINE_WIDTH / sizeof(unsigned long);
+	} while (--lines > 0);
+}
+
+void XOR_FUNC_NAME(3)(unsigned long bytes,
+		      unsigned long * __restrict v1,
+		      const unsigned long * __restrict v2,
+		      const unsigned long * __restrict v3)
+{
+	unsigned long lines = bytes / LINE_WIDTH;
+
+	do {
+		__asm__ __volatile__ (
+			LD_INOUT_LINE(v1)
+			LD_AND_XOR_LINE(v2)
+			LD_AND_XOR_LINE(v3)
+			ST_LINE(v1)
+		: : [v1] "r"(v1), [v2] "r"(v2), [v3] "r"(v3) : "memory"
+		);
+
+		v1 += LINE_WIDTH / sizeof(unsigned long);
+		v2 += LINE_WIDTH / sizeof(unsigned long);
+		v3 += LINE_WIDTH / sizeof(unsigned long);
+	} while (--lines > 0);
+}
+
+void XOR_FUNC_NAME(4)(unsigned long bytes,
+		      unsigned long * __restrict v1,
+		      const unsigned long * __restrict v2,
+		      const unsigned long * __restrict v3,
+		      const unsigned long * __restrict v4)
+{
+	unsigned long lines = bytes / LINE_WIDTH;
+
+	do {
+		__asm__ __volatile__ (
+			LD_INOUT_LINE(v1)
+			LD_AND_XOR_LINE(v2)
+			LD_AND_XOR_LINE(v3)
+			LD_AND_XOR_LINE(v4)
+			ST_LINE(v1)
+		: : [v1] "r"(v1), [v2] "r"(v2), [v3] "r"(v3), [v4] "r"(v4)
+		: "memory"
+		);
+
+		v1 += LINE_WIDTH / sizeof(unsigned long);
+		v2 += LINE_WIDTH / sizeof(unsigned long);
+		v3 += LINE_WIDTH / sizeof(unsigned long);
+		v4 += LINE_WIDTH / sizeof(unsigned long);
+	} while (--lines > 0);
+}
+
+void XOR_FUNC_NAME(5)(unsigned long bytes,
+		      unsigned long * __restrict v1,
+		      const unsigned long * __restrict v2,
+		      const unsigned long * __restrict v3,
+		      const unsigned long * __restrict v4,
+		      const unsigned long * __restrict v5)
+{
+	unsigned long lines = bytes / LINE_WIDTH;
+
+	do {
+		__asm__ __volatile__ (
+			LD_INOUT_LINE(v1)
+			LD_AND_XOR_LINE(v2)
+			LD_AND_XOR_LINE(v3)
+			LD_AND_XOR_LINE(v4)
+			LD_AND_XOR_LINE(v5)
+			ST_LINE(v1)
+		: : [v1] "r"(v1), [v2] "r"(v2), [v3] "r"(v3), [v4] "r"(v4),
+		    [v5] "r"(v5) : "memory"
+		);
+
+		v1 += LINE_WIDTH / sizeof(unsigned long);
+		v2 += LINE_WIDTH / sizeof(unsigned long);
+		v3 += LINE_WIDTH / sizeof(unsigned long);
+		v4 += LINE_WIDTH / sizeof(unsigned long);
+		v5 += LINE_WIDTH / sizeof(unsigned long);
+	} while (--lines > 0);
+}