linux-kernel - [PATCH v2 15/18] x86: optimized csum_add() is the same for 32bit and 64bit

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Message-Id: <20231205022418.1703007-24-viro@zeniv.linux.org.uk>
Date:   Tue,  5 Dec 2023 02:24:15 +0000
From:   Al Viro <viro@...iv.linux.org.uk>
To:     linux-arch@...r.kernel.org
Cc:     gus Gusenleitner Klaus <gus@...a.com>,
        Al Viro <viro@....linux.org.uk>,
        Thomas Gleixner <tglx@...utronix.de>,
        lkml <linux-kernel@...r.kernel.org>,
        Ingo Molnar <mingo@...hat.com>, "bp@...en8.de" <bp@...en8.de>,
        "dave.hansen@...ux.intel.com" <dave.hansen@...ux.intel.com>,
        "x86@...nel.org" <x86@...nel.org>,
        "David S. Miller" <davem@...emloft.net>,
        "dsahern@...nel.org" <dsahern@...nel.org>,
        "kuba@...nel.org" <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Eric Dumazet <edumazet@...gle.com>
Subject: [PATCH v2 15/18] x86: optimized csum_add() is the same for 32bit and 64bit

... and when gcc-8 becomes a requirement, we could simply switch to
generic version.

Signed-off-by: Al Viro <viro@...iv.linux.org.uk>
---
 arch/x86/include/asm/checksum.h    | 18 ++++++++++++++++++
 arch/x86/include/asm/checksum_64.h | 16 ----------------
 arch/x86/um/asm/checksum.h         | 17 +++++++++++++++++
 arch/x86/um/asm/checksum_64.h      |  9 ---------
 4 files changed, 35 insertions(+), 25 deletions(-)

diff --git a/arch/x86/include/asm/checksum.h b/arch/x86/include/asm/checksum.h
index c66fa797703a..5c0a730c7316 100644
--- a/arch/x86/include/asm/checksum.h
+++ b/arch/x86/include/asm/checksum.h
@@ -1,6 +1,24 @@
 /* SPDX-License-Identifier: GPL-2.0 */
 #ifndef _ASM_X86_CHECKSUM_H
 #define _ASM_X86_CHECKSUM_H
+
+static inline unsigned add32_with_carry(unsigned a, unsigned b)
+{
+	asm("addl %2,%0\n\t"
+	    "adcl $0,%0"
+	    : "=r" (a)
+	    : "0" (a), "rm" (b));
+	return a;
+}
+
+/* note: with gcc-8 or later generic csum_add() yields the same code */
+#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);
+}
+
 #ifdef CONFIG_GENERIC_CSUM
 # include <asm-generic/checksum.h>
 #else
diff --git a/arch/x86/include/asm/checksum_64.h b/arch/x86/include/asm/checksum_64.h
index e225a12cec68..c86db605c0fd 100644
--- a/arch/x86/include/asm/checksum_64.h
+++ b/arch/x86/include/asm/checksum_64.h
@@ -52,20 +52,4 @@ extern __sum16
 csum_ipv6_magic(const struct in6_addr *saddr, const struct in6_addr *daddr,
 		__u32 len, __u8 proto, __wsum sum);
 
-static inline unsigned add32_with_carry(unsigned a, unsigned b)
-{
-	asm("addl %2,%0\n\t"
-	    "adcl $0,%0"
-	    : "=r" (a)
-	    : "0" (a), "rm" (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/arch/x86/um/asm/checksum.h b/arch/x86/um/asm/checksum.h
index 9ef8ef4291f4..0986c19e5ff0 100644
--- a/arch/x86/um/asm/checksum.h
+++ b/arch/x86/um/asm/checksum.h
@@ -6,6 +6,23 @@
 #include <linux/in6.h>
 #include <linux/uaccess.h>
 
+static inline unsigned add32_with_carry(unsigned a, unsigned b)
+{
+	asm("addl %2,%0\n\t"
+	    "adcl $0,%0"
+	    : "=r" (a)
+	    : "0" (a), "rm" (b));
+	return a;
+}
+
+/* note: with gcc-8 or later generic csum_add() yields the same code */
+#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);
+}
+
 /*
  * computes the checksum of a memory block at buff, length len,
  * and adds in "sum" (32-bit)
diff --git a/arch/x86/um/asm/checksum_64.h b/arch/x86/um/asm/checksum_64.h
index fd1ab07e4a4c..17228e4c26b6 100644
--- a/arch/x86/um/asm/checksum_64.h
+++ b/arch/x86/um/asm/checksum_64.h
@@ -7,13 +7,4 @@
 
 #define _HAVE_IP_COMPUTE_CSUM
 
-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));
-        return a;
-}
-
 #endif
-- 
2.39.2