[PATCH net-next 1/6] net: Allow csum_add to be provided in arch

[PATCH net-next 1/6] net: Allow csum_add to be provided in arch

[Tom Herbert]

csum_add is really nothing more then add-with-carry which
can be implemented efficiently in some architectures.
Allow architecture to define this protected by HAVE_ARCH_CSUM_ADD.

Provide csum_add in for x86.

Signed-off-by: Tom Herbert <therbert@google.com>
---
 arch/x86/include/asm/checksum_64.h | 7 +++++++
 include/net/checksum.h             | 2 ++
 2 files changed, 9 insertions(+)

diff --git a/arch/x86/include/asm/checksum_64.h b/arch/x86/include/asm/checksum_64.h
index e6fd8a0..3581761 100644
--- a/arch/x86/include/asm/checksum_64.h
+++ b/arch/x86/include/asm/checksum_64.h
@@ -188,4 +188,11 @@ static inline unsigned add32_with_carry(unsigned a, unsigned b)
 	return a;
 }
 
+#define HAVE_ARCH_CSUM_ADD
+static inline __wsum csum_add(__wsum csum, __wsum addend)
+{
+	return (__force __wsum)add32_with_carry((__force unsigned)csum,
+						(__force unsigned)addend);
+}
+
 #endif /* _ASM_X86_CHECKSUM_64_H */
diff --git a/include/net/checksum.h b/include/net/checksum.h
index a28f4e0..87cb190 100644
--- a/include/net/checksum.h
+++ b/include/net/checksum.h
@@ -57,12 +57,14 @@ static __inline__ __wsum csum_and_copy_to_user
 }
 #endif
 
+#ifndef HAVE_ARCH_CSUM_ADD
 static inline __wsum csum_add(__wsum csum, __wsum addend)
 {
 	u32 res = (__force u32)csum;
 	res += (__force u32)addend;
 	return (__force __wsum)(res + (res < (__force u32)addend));
 }
+#endif
 
 static inline __wsum csum_sub(__wsum csum, __wsum addend)
 {
-- 
1.9.1.423.g4596e3a

Re: [PATCH net-next 1/6] net: Allow csum_add to be provided in arch

[Eric Dumazet]

On Fri, 2014-04-04 at 17:26 -0700, Tom Herbert wrote:
> csum_add is really nothing more then add-with-carry which
> can be implemented efficiently in some architectures.
> Allow architecture to define this protected by HAVE_ARCH_CSUM_ADD.
> 
> Provide csum_add in for x86.

[ net-next is closed during merge window ]

Not x86, but x86_64 only.

Note add32_with_carry(a, b) is suboptimal, as it forces
a and b in registers.

b could be a memory or a register operand.

diff --git a/arch/x86/include/asm/checksum_64.h b/arch/x86/include/asm/checksum_64.h
index e6fd8a026c7b..29f130d3c344 100644
--- a/arch/x86/include/asm/checksum_64.h
+++ b/arch/x86/include/asm/checksum_64.h
@@ -184,7 +184,7 @@ static inline unsigned add32_with_carry(unsigned a, unsigned b)
        asm("addl %2,%0\n\t"
            "adcl $0,%0"
            : "=r" (a)
-           : "0" (a), "r" (b));
+           : "0" (a), "rm" (b));
        return a;
 }

Re: [PATCH net-next 1/6] net: Allow csum_add to be provided in arch

[David Miller]

From: Tom Herbert <therbert@google.com>
Date: Fri, 4 Apr 2014 17:26:46 -0700 (PDT)

> csum_add is really nothing more then add-with-carry which
> can be implemented efficiently in some architectures.
> Allow architecture to define this protected by HAVE_ARCH_CSUM_ADD.
> 
> Provide csum_add in for x86.
> 
> Signed-off-by: Tom Herbert <therbert@google.com>

The Sparc version looks like this, feel free to integrate it into this
patch.

diff --git a/arch/sparc/include/asm/checksum_32.h b/arch/sparc/include/asm/checksum_32.h
index bdbda14..3297436 100644
--- a/arch/sparc/include/asm/checksum_32.h
+++ b/arch/sparc/include/asm/checksum_32.h
@@ -238,4 +238,15 @@ static inline __sum16 ip_compute_csum(const void *buff, int len)
 	return csum_fold(csum_partial(buff, len, 0));
 }
 
+#define HAVE_ARCH_CSUM_ADD
+static inline __wsum csum_add(__wsum csum, __wsum addend)
+{
+	__asm__ __volatile__(
+"	addcc	%0, %1, %0\n"
+"	addx	%0, %%g0, %0"
+	: "=r" (csum)
+	: "r" (addend), "0" (csum));
+	return csum;
+}
+
 #endif /* !(__SPARC_CHECKSUM_H) */
diff --git a/arch/sparc/include/asm/checksum_64.h b/arch/sparc/include/asm/checksum_64.h
index 019b961..38b24a3 100644
--- a/arch/sparc/include/asm/checksum_64.h
+++ b/arch/sparc/include/asm/checksum_64.h
@@ -164,4 +164,15 @@ static inline __sum16 ip_compute_csum(const void *buff, int len)
 	return csum_fold(csum_partial(buff, len, 0));
 }
 
+#define HAVE_ARCH_CSUM_ADD
+static inline __wsum csum_add(__wsum csum, __wsum addend)
+{
+	__asm__ __volatile__(
+"	addcc	%0, %1, %0\n"
+"	addc	%0, %%g0, %0"
+	: "=r" (csum)
+	: "r" (addend), "0" (csum));
+	return csum;
+}
+
 #endif /* !(__SPARC64_CHECKSUM_H) */