linux-kernel - [PATCH 2/2] arm:kvm remove len 8 for mmio read write buf

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Date:	Mon, 22 Dec 2014 19:23:19 +0800
From:	Peng Fan <van.freenix@...il.com>
To:	christoffer.dall@...aro.org, marc.zyngier@....com
Cc:	gleb@...nel.org, pbonzini@...hat.com, linux@....linux.org.uk,
	linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.cs.columbia.edu,
	kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
	van.freenix@...il.com
Subject: [PATCH 2/2] arm:kvm remove len 8 for mmio read write buf

For arm 32 bit architecture, 8 bytes load/store operation in one instruction
will not be generated by compiler.

And before invoke mmio_read_buf, there is a piece of code:
"
                 len = run->mmio.len;
                 if (len > sizeof(unsigned long))
                         return -EINVAL;

		data = mmio_read_buf(run->mmio.data, len);
"

This piece code also tells that len variable does not exceeds 4 bytes.
So, remove 8 bytes assign in mmio_read_buf and mmio_write_buf.

Signed-off-by: Peng Fan <van.freenix@...il.com>
CC: Gleb Natapov <gleb@...nel.org>
CC: Paolo Bonzini <pbonzini@...hat.com>
CC: Christoffer Dall <christoffer.dall@...aro.org>
CC: Marc Zyngier <marc.zyngier@....com>
CC: Russell King <linux@....linux.org.uk>
---
 arch/arm/kvm/mmio.c | 10 ----------
 1 file changed, 10 deletions(-)

diff --git a/arch/arm/kvm/mmio.c b/arch/arm/kvm/mmio.c
index 4cb5a93..953a819 100644
--- a/arch/arm/kvm/mmio.c
+++ b/arch/arm/kvm/mmio.c
@@ -30,7 +30,6 @@ static void mmio_write_buf(char *buf, unsigned int len, unsigned long data)
 		u8	byte;
 		u16	hword;
 		u32	word;
-		u64	dword;
 	} tmp;
 
 	switch (len) {
@@ -46,10 +45,6 @@ static void mmio_write_buf(char *buf, unsigned int len, unsigned long data)
 		tmp.word	= data;
 		datap		= &tmp.word;
 		break;
-	case 8:
-		tmp.dword	= data;
-		datap		= &tmp.dword;
-		break;
 	}
 
 	memcpy(buf, datap, len);
@@ -61,7 +56,6 @@ static unsigned long mmio_read_buf(char *buf, unsigned int len)
 	union {
 		u16	hword;
 		u32	word;
-		u64	dword;
 	} tmp;
 
 	switch (len) {
@@ -76,10 +70,6 @@ static unsigned long mmio_read_buf(char *buf, unsigned int len)
 		memcpy(&tmp.word, buf, len);
 		data = tmp.word;
 		break;
-	case 8:
-		memcpy(&tmp.dword, buf, len);
-		data = tmp.dword;
-		break;
 	}
 
 	return data;
-- 
1.8.4

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