linux-kernel - [PATCH 02/16] math128, x86_64: Implement {mul,add}

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Message-Id: <1351115634-8420-3-git-send-email-juri.lelli@gmail.com>
Date:	Wed, 24 Oct 2012 14:53:40 -0700
From:	Juri Lelli <juri.lelli@...il.com>
To:	peterz@...radead.org, tglx@...utronix.de
Cc:	mingo@...hat.com, rostedt@...dmis.org, oleg@...hat.com,
	fweisbec@...il.com, darren@...art.com, johan.eker@...csson.com,
	p.faure@...tech.ch, linux-kernel@...r.kernel.org,
	claudio@...dence.eu.com, michael@...rulasolutions.com,
	fchecconi@...il.com, tommaso.cucinotta@...up.it,
	juri.lelli@...il.com, nicola.manica@...i.unitn.it,
	luca.abeni@...tn.it, dhaval.giani@...il.com, hgu1972@...il.com,
	paulmck@...ux.vnet.ibm.com, raistlin@...ux.it,
	insop.song@...csson.com, liming.wang@...driver.com,
	jkacur@...hat.com, harald.gustafsson@...csson.com,
	vincent.guittot@...aro.org,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Ingo Molnar <mingo@...nel.org>,
	"H. Peter Anvin" <hpa@...or.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>
Subject: [PATCH 02/16] math128, x86_64: Implement {mul,add}_u128 in 64bit asm

From: Peter Zijlstra <a.p.zijlstra@...llo.nl>

Enable __int128 usage when available, if not, provide asm versions of
mul_u64_u64 and add_u128.

Cc: Ingo Molnar <mingo@...nel.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: H. Peter Anvin <hpa@...or.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@...llo.nl>
Link: http://lkml.kernel.org/n/tip-67zk6v8agsi8m7k1bdcd0srw@git.kernel.org
---
 arch/x86/include/asm/math128.h |   39 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 39 insertions(+)
 create mode 100644 arch/x86/include/asm/math128.h

diff --git a/arch/x86/include/asm/math128.h b/arch/x86/include/asm/math128.h
new file mode 100644
index 0000000..c0e2a6c
--- /dev/null
+++ b/arch/x86/include/asm/math128.h
@@ -0,0 +1,39 @@
+#ifndef _ASM_MATH128_H
+#define _ASM_MATH128_H
+
+#ifdef CONFIG_X86_64
+
+#ifdef __SIZEOF_INT128__
+#define ARCH_HAS_INT128
+#endif
+
+#ifndef ARCH_HAS_INT128
+
+static inline u128 mul_u64_u64(u64 a, u64 b)
+{
+       u128 res;
+
+       asm("mulq %2"
+               : "=a" (res.lo), "=d" (res.hi)
+               :  "rm" (b), "0" (a));
+
+       return res;
+}
+#define mul_u64_u64 mul_u64_u64
+
+static inline u128 add_u128(u128 a, u128 b)
+{
+       u128 res;
+
+       asm("addq %2,%0;\n"
+           "adcq %3,%1;\n"
+               : "=rm" (res.lo), "=rm" (res.hi)
+               : "r" (b.lo), "r" (b.hi), "0" (a.lo), "1" (a.hi));
+
+       return res;
+}
+#define add_u128 add_u128
+
+#endif /* ARCH_HAS_INT128 */
+#endif /* CONFIG_X86_64 */
+#endif /* _ASM_MATH128_H */
-- 
1.7.9.5

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