arm64/xor: use EOR3 instructions when available

Use the EOR3 instruction to implement xor_blocks() if the instruction is
available, which is the case if the CPU implements the SHA-3 extension.
This is about 20% faster on Apple M1 when using the 5-way version.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20211213140252.2856053-1-ardb@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

Author: ardbiesheuvel

arch/arm64/Kconfig

@@ -1545,6 +1545,12 @@ endmenu
 
 menu "ARMv8.2 architectural features"
 
+config AS_HAS_ARMV8_2
+       def_bool $(cc-option,-Wa$(comma)-march=armv8.2-a)
+
+config AS_HAS_SHA3
+       def_bool $(as-instr,.arch armv8.2-a+sha3)
+
 config ARM64_PMEM
 	bool "Enable support for persistent memory"
 	select ARCH_HAS_PMEM_API

arch/arm64/Makefile

@@ -58,6 +58,11 @@ stack_protector_prepare: prepare0
 					include/generated/asm-offsets.h))
 endif
 
+ifeq ($(CONFIG_AS_HAS_ARMV8_2), y)
+# make sure to pass the newest target architecture to -march.
+asm-arch := armv8.2-a
+endif
+
 # Ensure that if the compiler supports branch protection we default it
 # off, this will be overridden if we are using branch protection.
 branch-prot-flags-y += $(call cc-option,-mbranch-protection=none)

arch/arm64/lib/xor-neon.c

@@ -167,7 +167,7 @@ void xor_arm64_neon_5(unsigned long bytes, unsigned long *p1,
 	} while (--lines > 0);
 }
 
-struct xor_block_template const xor_block_inner_neon = {
+struct xor_block_template xor_block_inner_neon __ro_after_init = {
 	.name	= "__inner_neon__",
 	.do_2	= xor_arm64_neon_2,
 	.do_3	= xor_arm64_neon_3,
@@ -176,6 +176,151 @@ struct xor_block_template const xor_block_inner_neon = {
 };
 EXPORT_SYMBOL(xor_block_inner_neon);
 
+static inline uint64x2_t eor3(uint64x2_t p, uint64x2_t q, uint64x2_t r)
+{
+	uint64x2_t res;
+
+	asm(ARM64_ASM_PREAMBLE ".arch_extension sha3\n"
+	    "eor3 %0.16b, %1.16b, %2.16b, %3.16b"
+	    : "=w"(res) : "w"(p), "w"(q), "w"(r));
+	return res;
+}
+
+static void xor_arm64_eor3_3(unsigned long bytes, unsigned long *p1,
+			     unsigned long *p2, unsigned long *p3)
+{
+	uint64_t *dp1 = (uint64_t *)p1;
+	uint64_t *dp2 = (uint64_t *)p2;
+	uint64_t *dp3 = (uint64_t *)p3;
+
+	register uint64x2_t v0, v1, v2, v3;
+	long lines = bytes / (sizeof(uint64x2_t) * 4);
+
+	do {
+		/* p1 ^= p2 ^ p3 */
+		v0 = eor3(vld1q_u64(dp1 + 0), vld1q_u64(dp2 + 0),
+			  vld1q_u64(dp3 + 0));
+		v1 = eor3(vld1q_u64(dp1 + 2), vld1q_u64(dp2 + 2),
+			  vld1q_u64(dp3 + 2));
+		v2 = eor3(vld1q_u64(dp1 + 4), vld1q_u64(dp2 + 4),
+			  vld1q_u64(dp3 + 4));
+		v3 = eor3(vld1q_u64(dp1 + 6), vld1q_u64(dp2 + 6),
+			  vld1q_u64(dp3 + 6));
+
+		/* store */
+		vst1q_u64(dp1 + 0, v0);
+		vst1q_u64(dp1 + 2, v1);
+		vst1q_u64(dp1 + 4, v2);
+		vst1q_u64(dp1 + 6, v3);
+
+		dp1 += 8;
+		dp2 += 8;
+		dp3 += 8;
+	} while (--lines > 0);
+}
+
+static void xor_arm64_eor3_4(unsigned long bytes, unsigned long *p1,
+			     unsigned long *p2, unsigned long *p3,
+			     unsigned long *p4)
+{
+	uint64_t *dp1 = (uint64_t *)p1;
+	uint64_t *dp2 = (uint64_t *)p2;
+	uint64_t *dp3 = (uint64_t *)p3;
+	uint64_t *dp4 = (uint64_t *)p4;
+
+	register uint64x2_t v0, v1, v2, v3;
+	long lines = bytes / (sizeof(uint64x2_t) * 4);
+
+	do {
+		/* p1 ^= p2 ^ p3 */
+		v0 = eor3(vld1q_u64(dp1 + 0), vld1q_u64(dp2 + 0),
+			  vld1q_u64(dp3 + 0));
+		v1 = eor3(vld1q_u64(dp1 + 2), vld1q_u64(dp2 + 2),
+			  vld1q_u64(dp3 + 2));
+		v2 = eor3(vld1q_u64(dp1 + 4), vld1q_u64(dp2 + 4),
+			  vld1q_u64(dp3 + 4));
+		v3 = eor3(vld1q_u64(dp1 + 6), vld1q_u64(dp2 + 6),
+			  vld1q_u64(dp3 + 6));
+
+		/* p1 ^= p4 */
+		v0 = veorq_u64(v0, vld1q_u64(dp4 + 0));
+		v1 = veorq_u64(v1, vld1q_u64(dp4 + 2));
+		v2 = veorq_u64(v2, vld1q_u64(dp4 + 4));
+		v3 = veorq_u64(v3, vld1q_u64(dp4 + 6));
+
+		/* store */
+		vst1q_u64(dp1 + 0, v0);
+		vst1q_u64(dp1 + 2, v1);
+		vst1q_u64(dp1 + 4, v2);
+		vst1q_u64(dp1 + 6, v3);
+
+		dp1 += 8;
+		dp2 += 8;
+		dp3 += 8;
+		dp4 += 8;
+	} while (--lines > 0);
+}
+
+static void xor_arm64_eor3_5(unsigned long bytes, unsigned long *p1,
+			     unsigned long *p2, unsigned long *p3,
+			     unsigned long *p4, unsigned long *p5)
+{
+	uint64_t *dp1 = (uint64_t *)p1;
+	uint64_t *dp2 = (uint64_t *)p2;
+	uint64_t *dp3 = (uint64_t *)p3;
+	uint64_t *dp4 = (uint64_t *)p4;
+	uint64_t *dp5 = (uint64_t *)p5;
+
+	register uint64x2_t v0, v1, v2, v3;
+	long lines = bytes / (sizeof(uint64x2_t) * 4);
+
+	do {
+		/* p1 ^= p2 ^ p3 */
+		v0 = eor3(vld1q_u64(dp1 + 0), vld1q_u64(dp2 + 0),
+			  vld1q_u64(dp3 + 0));
+		v1 = eor3(vld1q_u64(dp1 + 2), vld1q_u64(dp2 + 2),
+			  vld1q_u64(dp3 + 2));
+		v2 = eor3(vld1q_u64(dp1 + 4), vld1q_u64(dp2 + 4),
+			  vld1q_u64(dp3 + 4));
+		v3 = eor3(vld1q_u64(dp1 + 6), vld1q_u64(dp2 + 6),
+			  vld1q_u64(dp3 + 6));
+
+		/* p1 ^= p4 ^ p5 */
+		v0 = eor3(v0, vld1q_u64(dp4 + 0), vld1q_u64(dp5 + 0));
+		v1 = eor3(v1, vld1q_u64(dp4 + 2), vld1q_u64(dp5 + 2));
+		v2 = eor3(v2, vld1q_u64(dp4 + 4), vld1q_u64(dp5 + 4));
+		v3 = eor3(v3, vld1q_u64(dp4 + 6), vld1q_u64(dp5 + 6));
+
+		/* store */
+		vst1q_u64(dp1 + 0, v0);
+		vst1q_u64(dp1 + 2, v1);
+		vst1q_u64(dp1 + 4, v2);
+		vst1q_u64(dp1 + 6, v3);
+
+		dp1 += 8;
+		dp2 += 8;
+		dp3 += 8;
+		dp4 += 8;
+		dp5 += 8;
+	} while (--lines > 0);
+}
+
+static int __init xor_neon_init(void)
+{
+	if (IS_ENABLED(CONFIG_AS_HAS_SHA3) && cpu_have_named_feature(SHA3)) {
+		xor_block_inner_neon.do_3 = xor_arm64_eor3_3;
+		xor_block_inner_neon.do_4 = xor_arm64_eor3_4;
+		xor_block_inner_neon.do_5 = xor_arm64_eor3_5;
+	}
+	return 0;
+}
+module_init(xor_neon_init);
+
+static void __exit xor_neon_exit(void)
+{
+}
+module_exit(xor_neon_exit);
+
 MODULE_AUTHOR("Jackie Liu <liuyun01@kylinos.cn>");
 MODULE_DESCRIPTION("ARMv8 XOR Extensions");
 MODULE_LICENSE("GPL");