s390/checksum: provide vector register variant of csum_partial()

Provide a faster variant of csum_partial() which uses vector registers
instead of the cksm instruction.

Signed-off-by: Heiko Carstens <[e-mail]>

arch/s390/include/asm/checksum.h

···
 	return sum;
 }
 
-/*
- * Computes the checksum of a memory block at buff, length len,
- * and adds in "sum" (32-bit).
- *
- * Returns a 32-bit number suitable for feeding into itself
- * or csum_tcpudp_magic.
- *
- * This function must be called with even lengths, except
- * for the last fragment, which may be odd.
- *
- * It's best to have buff aligned on a 32-bit boundary.
- */
-static inline __wsum csum_partial(const void *buff, int len, __wsum sum)
-{
-	return cksm(buff, len, sum);
-}
+__wsum csum_partial(const void *buff, int len, __wsum sum);
 
 /*
  * Fold a partial checksum without adding pseudo headers.

arch/s390/include/asm/fpu-insn-asm.h

···
 	VMRL	\vr1, \vr2, \vr3, 3
 .endm
 
+/* VECTOR LOAD WITH LENGTH */
+.macro VLL	v, gr, disp, base
+	VX_NUM	v1, \v
+	GR_NUM	b2, \base
+	GR_NUM	r3, \gr
+	.word	0xE700 | ((v1&15) << 4) | r3
+	.word	(b2 << 12) | (\disp)
+	MRXBOPC 0, 0x37, v1
+.endm
 
 /* Vector integer instructions */
 
···
 	.word	0xE700 | ((v1&15) << 4) | (v2&15)
 	.word	((v3&15) << 12)
 	MRXBOPC	0, 0x68, v1, v2, v3
+.endm
+
+/* VECTOR CHECKSUM */
+.macro VCKSM	vr1, vr2, vr3
+	VX_NUM	v1, \vr1
+	VX_NUM	v2, \vr2
+	VX_NUM	v3, \vr3
+	.word	0xE700 | ((v1&15) << 4) | (v2&15)
+	.word	((v3&15) << 12)
+	MRXBOPC 0, 0x66, v1, v2, v3
 .endm
 
 /* VECTOR EXCLUSIVE OR */

arch/s390/include/asm/fpu-insn.h

···
 		     : "memory");
 }
 
+static __always_inline void fpu_vcksm(u8 v1, u8 v2, u8 v3)
+{
+	asm volatile("VCKSM	%[v1],%[v2],%[v3]"
+		     :
+		     : [v1] "I" (v1), [v2] "I" (v2), [v3] "I" (v3)
+		     : "memory");
+}
+
+#ifdef CONFIG_CC_IS_CLANG
+
+static __always_inline void fpu_vl(u8 v1, const void *vxr)
+{
+	instrument_read(vxr, sizeof(__vector128));
+	asm volatile("\n"
+		"	la	1,%[vxr]\n"
+		"	VL	%[v1],0,,1\n"
+		:
+		: [vxr] "R" (*(__vector128 *)vxr),
+		  [v1] "I" (v1)
+		: "memory", "1");
+}
+
+#else /* CONFIG_CC_IS_CLANG */
+
+static __always_inline void fpu_vl(u8 v1, const void *vxr)
+{
+	instrument_read(vxr, sizeof(__vector128));
+	asm volatile("VL	%[v1],%O[vxr],,%R[vxr]\n"
+		     :
+		     : [vxr] "Q" (*(__vector128 *)vxr),
+		       [v1] "I" (v1)
+		     : "memory");
+}
+
+#endif /* CONFIG_CC_IS_CLANG */
+
+static __always_inline u64 fpu_vlgvf(u8 v, u16 index)
+{
+	u64 val;
+
+	asm volatile("VLGVF	%[val],%[v],%[index]"
+		     : [val] "=d" (val)
+		     : [v] "I" (v), [index] "L" (index)
+		     : "memory");
+	return val;
+}
+
+#ifdef CONFIG_CC_IS_CLANG
+
+static __always_inline void fpu_vll(u8 v1, u32 index, const void *vxr)
+{
+	unsigned int size;
+
+	size = min(index + 1, sizeof(__vector128));
+	instrument_read(vxr, size);
+	asm volatile("\n"
+		"	la	1,%[vxr]\n"
+		"	VLL	%[v1],%[index],0,1\n"
+		:
+		: [vxr] "R" (*(u8 *)vxr),
+		  [index] "d" (index),
+		  [v1] "I" (v1)
+		: "memory", "1");
+}
+
+#else /* CONFIG_CC_IS_CLANG */
+
+static __always_inline void fpu_vll(u8 v1, u32 index, const void *vxr)
+{
+	unsigned int size;
+
+	size = min(index + 1, sizeof(__vector128));
+	instrument_read(vxr, size);
+	asm volatile("VLL	%[v1],%[index],%O[vxr],%R[vxr]\n"
+		     :
+		     : [vxr] "Q" (*(u8 *)vxr),
+		       [index] "d" (index),
+		       [v1] "I" (v1)
+		     : "memory");
+}
+
+#endif /* CONFIG_CC_IS_CLANG */
+
 #ifdef CONFIG_CC_IS_CLANG
 
 #define fpu_vlm(_v1, _v3, _vxrs)					\
···
 
 #endif /* CONFIG_CC_IS_CLANG */
 
+static __always_inline void fpu_vlvgf(u8 v, u32 val, u16 index)
+{
+	asm volatile("VLVGF	%[v],%[val],%[index]"
+		     :
+		     : [v] "I" (v), [val] "d" (val), [index] "L" (index)
+		     : "memory");
+}
+
 #ifdef CONFIG_CC_IS_CLANG
 
 #define fpu_vstm(_v1, _v3, _vxrs)					\
···
 })
 
 #endif /* CONFIG_CC_IS_CLANG */
+
+static __always_inline void fpu_vzero(u8 v)
+{
+	asm volatile("VZERO	%[v]"
+		     :
+		     : [v] "I" (v)
+		     : "memory");
+}
 
 #endif /* __ASSEMBLY__ */
 #endif	/* __ASM_S390_FPU_INSN_H */

arch/s390/include/asm/fpu-types.h

···
 	__vector128 vxrs[vxr_size] __aligned(8);		\
 }
 
+KERNEL_FPU_STRUCT(8);
 KERNEL_FPU_STRUCT(16);
 KERNEL_FPU_STRUCT(32);
 
 #define DECLARE_KERNEL_FPU_ONSTACK(vxr_size, name)		\
 	struct kernel_fpu_##vxr_size name __uninitialized
+
+#define DECLARE_KERNEL_FPU_ONSTACK8(name)			\
+	DECLARE_KERNEL_FPU_ONSTACK(8, name)
 
 #define DECLARE_KERNEL_FPU_ONSTACK16(name)			\
 	DECLARE_KERNEL_FPU_ONSTACK(16, name)

arch/s390/lib/Makefile

···
 #
 
 lib-y += delay.o string.o uaccess.o find.o spinlock.o tishift.o
+lib-y += csum-partial.o
 obj-y += mem.o xor.o
 lib-$(CONFIG_KPROBES) += probes.o
 lib-$(CONFIG_UPROBES) += probes.o

arch/s390/lib/csum-partial.c

···
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/export.h>
+#include <asm/checksum.h>
+#include <asm/fpu.h>
+
+/*
+ * Computes the checksum of a memory block at buff, length len,
+ * and adds in "sum" (32-bit).
+ *
+ * Returns a 32-bit number suitable for feeding into itself
+ * or csum_tcpudp_magic.
+ *
+ * This function must be called with even lengths, except
+ * for the last fragment, which may be odd.
+ *
+ * It's best to have buff aligned on a 64-bit boundary.
+ */
+__wsum csum_partial(const void *buff, int len, __wsum sum)
+{
+	DECLARE_KERNEL_FPU_ONSTACK8(vxstate);
+
+	if (!cpu_has_vx())
+		return cksm(buff, len, sum);
+	kernel_fpu_begin(&vxstate, KERNEL_VXR_V16V23);
+	fpu_vlvgf(16, (__force u32)sum, 1);
+	fpu_vzero(17);
+	fpu_vzero(18);
+	fpu_vzero(19);
+	while (len >= 64) {
+		fpu_vlm(20, 23, buff);
+		fpu_vcksm(16, 20, 16);
+		fpu_vcksm(17, 21, 17);
+		fpu_vcksm(18, 22, 18);
+		fpu_vcksm(19, 23, 19);
+		buff += 64;
+		len -= 64;
+	}
+	while (len >= 32) {
+		fpu_vlm(20, 21, buff);
+		fpu_vcksm(16, 20, 16);
+		fpu_vcksm(17, 21, 17);
+		buff += 32;
+		len -= 32;
+	}
+	while (len >= 16) {
+		fpu_vl(20, buff);
+		fpu_vcksm(16, 20, 16);
+		buff += 16;
+		len -= 16;
+	}
+	if (len) {
+		fpu_vll(20, len - 1, buff);
+		fpu_vcksm(16, 20, 16);
+	}
+	fpu_vcksm(18, 19, 18);
+	fpu_vcksm(16, 17, 16);
+	fpu_vcksm(16, 18, 16);
+	sum = (__force __wsum)fpu_vlgvf(16, 1);
+	kernel_fpu_end(&vxstate, KERNEL_VXR_V16V23);
+	return sum;
+}
+EXPORT_SYMBOL(csum_partial);