[v8,3/5] riscv: Checksum header

Commit Message

Charlie Jenkins Oct. 27, 2023, 10:43 p.m. UTC

Provide checksum algorithms that have been designed to leverage riscv
instructions such as rotate. In 64-bit, can take advantage of the larger
register to avoid some overflow checking.

Signed-off-by: Charlie Jenkins <[e-mail]>
Acked-by: Conor Dooley <[e-mail]>
---
 arch/riscv/include/asm/checksum.h | 92 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 92 insertions(+)

Comments

Wang, Xiao W Oct. 31, 2023, 9:11 a.m. UTC | #1

> -----Original Message-----
> From: Charlie Jenkins <[e-mail]>
> Sent: Saturday, October 28, 2023 6:44 AM
> To: Charlie Jenkins <[e-mail]>; Palmer Dabbelt
> <[e-mail]>; Conor Dooley <[e-mail]>; Samuel Holland
> <[e-mail]>; David Laight <[e-mail]>;
> Wang, Xiao W <[e-mail]>; Evan Green <[e-mail]>;
> [e-mail]; [e-mail]; linux-
> [e-mail]
> Cc: Paul Walmsley <[e-mail]>; Albert Ou
> <[e-mail]>; Arnd Bergmann <[e-mail]>; Conor Dooley
> <[e-mail]>
> Subject: [PATCH v8 3/5] riscv: Checksum header
> 
> Provide checksum algorithms that have been designed to leverage riscv
> instructions such as rotate. In 64-bit, can take advantage of the larger
> register to avoid some overflow checking.
> 
> Signed-off-by: Charlie Jenkins <[e-mail]>
> Acked-by: Conor Dooley <[e-mail]>
> ---
>  arch/riscv/include/asm/checksum.h | 92
> +++++++++++++++++++++++++++++++++++++++
>  1 file changed, 92 insertions(+)
> 
> diff --git a/arch/riscv/include/asm/checksum.h
> b/arch/riscv/include/asm/checksum.h
> new file mode 100644
> index 000000000000..9fd4b1b80641
> --- /dev/null
> +++ b/arch/riscv/include/asm/checksum.h
> @@ -0,0 +1,92 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * IP checksum routines

The checksum helpers' usage may not be limited to IP protocol.

> + *
> + * Copyright (C) 2023 Rivos Inc.
> + */
> +#ifndef __ASM_RISCV_CHECKSUM_H
> +#define __ASM_RISCV_CHECKSUM_H
> +
> +#include <linux/in6.h>
> +#include <linux/uaccess.h>
> +
> +#define ip_fast_csum ip_fast_csum
> +
> +extern unsigned int do_csum(const unsigned char *buff, int len);
> +#define do_csum do_csum
> +
> +/* Default version is sufficient for 32 bit */
> +#ifdef CONFIG_64BIT
> +#define _HAVE_ARCH_IPV6_CSUM
> +__sum16 csum_ipv6_magic(const struct in6_addr *saddr,
> +			const struct in6_addr *daddr,
> +			__u32 len, __u8 proto, __wsum sum);
> +#endif

The do_csum and csum_ipv6_magic helpers are implemented in patch 4/5, so the
declarations should be moved there. Otherwise, build would fail at this patch.

> +
> +/* Define riscv versions of functions before importing asm-
> generic/checksum.h */
> +#include <asm-generic/checksum.h>
> +
> +/*
> + * Quickly compute an IP checksum with the assumption that IPv4 headers
> will
> + * always be in multiples of 32-bits, and have an ihl of at least 5.
> + * @ihl is the number of 32 bit segments and must be greater than or equal
> to 5.
> + * @iph is assumed to be word aligned given that NET_IP_ALIGN is set to 2 on
> + *	riscv, defining IP headers to be aligned.
> + */
> +static inline __sum16 ip_fast_csum(const void *iph, unsigned int ihl)
> +{
> +	unsigned long csum = 0;
> +	int pos = 0;
> +
> +	do {
> +		csum += ((const unsigned int *)iph)[pos];
> +		if (IS_ENABLED(CONFIG_32BIT))
> +			csum += csum < ((const unsigned int *)iph)[pos];
> +	} while (++pos < ihl);
> +
> +	/*
> +	 * ZBB only saves three instructions on 32-bit and five on 64-bit so not
> +	 * worth checking if supported without Alternatives.
> +	 */
> +	if (IS_ENABLED(CONFIG_RISCV_ISA_ZBB) &&
> +	    IS_ENABLED(CONFIG_RISCV_ALTERNATIVE)) {
> +		unsigned long fold_temp;
> +
> +		asm_volatile_goto(ALTERNATIVE("j %l[no_zbb]", "nop", 0,
> +					      RISCV_ISA_EXT_ZBB, 1)
> +		    :
> +		    :
> +		    :
> +		    : no_zbb);
> +
> +		if (IS_ENABLED(CONFIG_32BIT)) {
> +			asm(".option push				\n\
> +			.option arch,+zbb				\n\
> +				not	%[fold_temp], %[csum]
> 	\n\
> +				rori	%[csum], %[csum], 16		\n\
> +				sub	%[csum], %[fold_temp], %[csum]
> 	\n\
> +			.option pop"
> +			: [csum] "+r" (csum), [fold_temp] "=&r" (fold_temp));
> +		} else {
> +			asm(".option push				\n\
> +			.option arch,+zbb				\n\
> +				rori	%[fold_temp], %[csum], 32	\n\
> +				add	%[csum], %[fold_temp], %[csum]
> 	\n\
> +				srli	%[csum], %[csum], 32		\n\
> +				not	%[fold_temp], %[csum]
> 	\n\
> +				roriw	%[csum], %[csum], 16		\n\
> +				subw	%[csum], %[fold_temp], %[csum]
> 	\n\
> +			.option pop"
> +			: [csum] "+r" (csum), [fold_temp] "=&r" (fold_temp));
> +		}
> +		return csum >> 16;
> +	}
> +no_zbb:
> +#ifndef CONFIG_32BIT
> +	csum += (csum >> 32) | (csum << 32);

Just like the next patch does, we can call ror64(csum, 32).

BRs,
Xiao

> +	csum >>= 32;
> +#endif
> +	return csum_fold((__force __wsum)csum);
> +}
> +
> +#endif /* __ASM_RISCV_CHECKSUM_H */
> 
> --
> 2.42.0

Charlie Jenkins Oct. 31, 2023, 10:53 p.m. UTC | #2

On Tue, Oct 31, 2023 at 09:11:07AM +0000, Wang, Xiao W wrote:
> 
> 
> > -----Original Message-----
> > From: Charlie Jenkins <[e-mail]>
> > Sent: Saturday, October 28, 2023 6:44 AM
> > To: Charlie Jenkins <[e-mail]>; Palmer Dabbelt
> > <[e-mail]>; Conor Dooley <[e-mail]>; Samuel Holland
> > <[e-mail]>; David Laight <[e-mail]>;
> > Wang, Xiao W <[e-mail]>; Evan Green <[e-mail]>;
> > [e-mail]; [e-mail]; linux-
> > [e-mail]
> > Cc: Paul Walmsley <[e-mail]>; Albert Ou
> > <[e-mail]>; Arnd Bergmann <[e-mail]>; Conor Dooley
> > <[e-mail]>
> > Subject: [PATCH v8 3/5] riscv: Checksum header
> > 
> > Provide checksum algorithms that have been designed to leverage riscv
> > instructions such as rotate. In 64-bit, can take advantage of the larger
> > register to avoid some overflow checking.
> > 
> > Signed-off-by: Charlie Jenkins <[e-mail]>
> > Acked-by: Conor Dooley <[e-mail]>
> > ---
> >  arch/riscv/include/asm/checksum.h | 92
> > +++++++++++++++++++++++++++++++++++++++
> >  1 file changed, 92 insertions(+)
> > 
> > diff --git a/arch/riscv/include/asm/checksum.h
> > b/arch/riscv/include/asm/checksum.h
> > new file mode 100644
> > index 000000000000..9fd4b1b80641
> > --- /dev/null
> > +++ b/arch/riscv/include/asm/checksum.h
> > @@ -0,0 +1,92 @@
> > +/* SPDX-License-Identifier: GPL-2.0 */
> > +/*
> > + * IP checksum routines
> 
> The checksum helpers' usage may not be limited to IP protocol.
> 

Will remove IP from the wording.

> > + *
> > + * Copyright (C) 2023 Rivos Inc.
> > + */
> > +#ifndef __ASM_RISCV_CHECKSUM_H
> > +#define __ASM_RISCV_CHECKSUM_H
> > +
> > +#include <linux/in6.h>
> > +#include <linux/uaccess.h>
> > +
> > +#define ip_fast_csum ip_fast_csum
> > +
> > +extern unsigned int do_csum(const unsigned char *buff, int len);
> > +#define do_csum do_csum
> > +
> > +/* Default version is sufficient for 32 bit */
> > +#ifdef CONFIG_64BIT
> > +#define _HAVE_ARCH_IPV6_CSUM
> > +__sum16 csum_ipv6_magic(const struct in6_addr *saddr,
> > +			const struct in6_addr *daddr,
> > +			__u32 len, __u8 proto, __wsum sum);
> > +#endif
> 
> The do_csum and csum_ipv6_magic helpers are implemented in patch 4/5, so the
> declarations should be moved there. Otherwise, build would fail at this patch.
> 

Oops, that snuck into this patch somehow.

> > +
> > +/* Define riscv versions of functions before importing asm-
> > generic/checksum.h */
> > +#include <asm-generic/checksum.h>
> > +
> > +/*
> > + * Quickly compute an IP checksum with the assumption that IPv4 headers
> > will
> > + * always be in multiples of 32-bits, and have an ihl of at least 5.
> > + * @ihl is the number of 32 bit segments and must be greater than or equal
> > to 5.
> > + * @iph is assumed to be word aligned given that NET_IP_ALIGN is set to 2 on
> > + *	riscv, defining IP headers to be aligned.
> > + */
> > +static inline __sum16 ip_fast_csum(const void *iph, unsigned int ihl)
> > +{
> > +	unsigned long csum = 0;
> > +	int pos = 0;
> > +
> > +	do {
> > +		csum += ((const unsigned int *)iph)[pos];
> > +		if (IS_ENABLED(CONFIG_32BIT))
> > +			csum += csum < ((const unsigned int *)iph)[pos];
> > +	} while (++pos < ihl);
> > +
> > +	/*
> > +	 * ZBB only saves three instructions on 32-bit and five on 64-bit so not
> > +	 * worth checking if supported without Alternatives.
> > +	 */
> > +	if (IS_ENABLED(CONFIG_RISCV_ISA_ZBB) &&
> > +	    IS_ENABLED(CONFIG_RISCV_ALTERNATIVE)) {
> > +		unsigned long fold_temp;
> > +
> > +		asm_volatile_goto(ALTERNATIVE("j %l[no_zbb]", "nop", 0,
> > +					      RISCV_ISA_EXT_ZBB, 1)
> > +		    :
> > +		    :
> > +		    :
> > +		    : no_zbb);
> > +
> > +		if (IS_ENABLED(CONFIG_32BIT)) {
> > +			asm(".option push				\n\
> > +			.option arch,+zbb				\n\
> > +				not	%[fold_temp], %[csum]
> > 	\n\
> > +				rori	%[csum], %[csum], 16		\n\
> > +				sub	%[csum], %[fold_temp], %[csum]
> > 	\n\
> > +			.option pop"
> > +			: [csum] "+r" (csum), [fold_temp] "=&r" (fold_temp));
> > +		} else {
> > +			asm(".option push				\n\
> > +			.option arch,+zbb				\n\
> > +				rori	%[fold_temp], %[csum], 32	\n\
> > +				add	%[csum], %[fold_temp], %[csum]
> > 	\n\
> > +				srli	%[csum], %[csum], 32		\n\
> > +				not	%[fold_temp], %[csum]
> > 	\n\
> > +				roriw	%[csum], %[csum], 16		\n\
> > +				subw	%[csum], %[fold_temp], %[csum]
> > 	\n\
> > +			.option pop"
> > +			: [csum] "+r" (csum), [fold_temp] "=&r" (fold_temp));
> > +		}
> > +		return csum >> 16;
> > +	}
> > +no_zbb:
> > +#ifndef CONFIG_32BIT
> > +	csum += (csum >> 32) | (csum << 32);
> 
> Just like the next patch does, we can call ror64(csum, 32).

I meant to change this last time, thank you for pointing it out again.

- Charlie

> 
> BRs,
> Xiao
> 
> > +	csum >>= 32;
> > +#endif
> > +	return csum_fold((__force __wsum)csum);
> > +}
> > +
> > +#endif /* __ASM_RISCV_CHECKSUM_H */
> > 
> > --
> > 2.42.0
>

Patch

diff --git a/arch/riscv/include/asm/checksum.h b/arch/riscv/include/asm/checksum.h
new file mode 100644
index 000000000000..9fd4b1b80641
--- /dev/null
+++ b/arch/riscv/include/asm/checksum.h
@@ -0,0 +1,92 @@ 
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * IP checksum routines
+ *
+ * Copyright (C) 2023 Rivos Inc.
+ */
+#ifndef __ASM_RISCV_CHECKSUM_H
+#define __ASM_RISCV_CHECKSUM_H
+
+#include <linux/in6.h>
+#include <linux/uaccess.h>
+
+#define ip_fast_csum ip_fast_csum
+
+extern unsigned int do_csum(const unsigned char *buff, int len);
+#define do_csum do_csum
+
+/* Default version is sufficient for 32 bit */
+#ifdef CONFIG_64BIT
+#define _HAVE_ARCH_IPV6_CSUM
+__sum16 csum_ipv6_magic(const struct in6_addr *saddr,
+			const struct in6_addr *daddr,
+			__u32 len, __u8 proto, __wsum sum);
+#endif
+
+/* Define riscv versions of functions before importing asm-generic/checksum.h */
+#include <asm-generic/checksum.h>
+
+/*
+ * Quickly compute an IP checksum with the assumption that IPv4 headers will
+ * always be in multiples of 32-bits, and have an ihl of at least 5.
+ * @ihl is the number of 32 bit segments and must be greater than or equal to 5.
+ * @iph is assumed to be word aligned given that NET_IP_ALIGN is set to 2 on
+ *	riscv, defining IP headers to be aligned.
+ */
+static inline __sum16 ip_fast_csum(const void *iph, unsigned int ihl)
+{
+	unsigned long csum = 0;
+	int pos = 0;
+
+	do {
+		csum += ((const unsigned int *)iph)[pos];
+		if (IS_ENABLED(CONFIG_32BIT))
+			csum += csum < ((const unsigned int *)iph)[pos];
+	} while (++pos < ihl);
+
+	/*
+	 * ZBB only saves three instructions on 32-bit and five on 64-bit so not
+	 * worth checking if supported without Alternatives.
+	 */
+	if (IS_ENABLED(CONFIG_RISCV_ISA_ZBB) &&
+	    IS_ENABLED(CONFIG_RISCV_ALTERNATIVE)) {
+		unsigned long fold_temp;
+
+		asm_volatile_goto(ALTERNATIVE("j %l[no_zbb]", "nop", 0,
+					      RISCV_ISA_EXT_ZBB, 1)
+		    :
+		    :
+		    :
+		    : no_zbb);
+
+		if (IS_ENABLED(CONFIG_32BIT)) {
+			asm(".option push				\n\
+			.option arch,+zbb				\n\
+				not	%[fold_temp], %[csum]		\n\
+				rori	%[csum], %[csum], 16		\n\
+				sub	%[csum], %[fold_temp], %[csum]	\n\
+			.option pop"
+			: [csum] "+r" (csum), [fold_temp] "=&r" (fold_temp));
+		} else {
+			asm(".option push				\n\
+			.option arch,+zbb				\n\
+				rori	%[fold_temp], %[csum], 32	\n\
+				add	%[csum], %[fold_temp], %[csum]	\n\
+				srli	%[csum], %[csum], 32		\n\
+				not	%[fold_temp], %[csum]		\n\
+				roriw	%[csum], %[csum], 16		\n\
+				subw	%[csum], %[fold_temp], %[csum]	\n\
+			.option pop"
+			: [csum] "+r" (csum), [fold_temp] "=&r" (fold_temp));
+		}
+		return csum >> 16;
+	}
+no_zbb:
+#ifndef CONFIG_32BIT
+	csum += (csum >> 32) | (csum << 32);
+	csum >>= 32;
+#endif
+	return csum_fold((__force __wsum)csum);
+}
+
+#endif /* __ASM_RISCV_CHECKSUM_H */