linux-kernel - [PATCH] i386: msr.h: be paranoid about types and parentheses

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Date:	Wed, 9 May 2007 00:02:11 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andi Kleen <ak@...e.de>,
	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	"H. Peter Anvin" <hpa@...or.com>
Subject: [PATCH] i386: msr.h: be paranoid about types and parentheses

When implementing things as macros, make sure we use typecasts and
parentheses where needed.  The macros as defined were vulnerable to
surreptitious promotion causing problems.

Avoid macros where practical; e.g. wrmsr() can be an inline instead.

Signed-off-by: H. Peter Anvin <hpa@...or.com>
---

This patch depends on the previous patch, "i386: remove unused rdtsc() macro".

 include/asm-i386/msr.h |   49 +++++++++++++++++++++--------------------------
 1 files changed, 22 insertions(+), 27 deletions(-)

diff --git a/include/asm-i386/msr.h b/include/asm-i386/msr.h
index c70773e..df21ea0 100644
--- a/include/asm-i386/msr.h
+++ b/include/asm-i386/msr.h
@@ -86,55 +86,50 @@ static inline unsigned long long native_read_pmc(void)
 
 #define rdmsr(msr,val1,val2)						\
 	do {								\
-		unsigned long long __val = native_read_msr(msr);	\
-		val1 = __val;						\
-		val2 = __val >> 32;					\
+		u64 __val = native_read_msr(msr);			\
+		(val1) = (u32)__val;					\
+		(val2) = (u32)(__val >> 32);				\
 	} while(0)
 
-#define wrmsr(msr,val1,val2)						\
-	native_write_msr(msr, ((unsigned long long)val2 << 32) | val1)
-
-#define rdmsrl(msr,val)					\
-	do {						\
-		(val) = native_read_msr(msr);		\
-	} while(0)
-
-static inline void wrmsrl (unsigned long msr, unsigned long long val)
+static inline void wrmsr(u32 __msr, u32 __low, u32 __high)
 {
-	unsigned long lo, hi;
-	lo = (unsigned long) val;
-	hi = val >> 32;
-	wrmsr (msr, lo, hi);
+	native_write_msr(__msr, ((u64)__high << 32) | __low);
 }
 
+#define rdmsrl(msr,val)							\
+	((val) = native_read_msr(msr))
+
+#define wrmsrl(msr,val)	native_write_msr(msr, val)
+
 /* wrmsr with exception handling */
-#define wrmsr_safe(msr,val1,val2)						\
-	(native_write_msr_safe(msr, ((unsigned long long)val2 << 32) | val1))
+static inline int wrmsr_safe(u32 __msr, u32 __low, u32 __high)
+{
+	return native_write_msr_safe(__msr, ((u64)__high << 32) | __low);
+}
 
 /* rdmsr with exception handling */
 #define rdmsr_safe(msr,p1,p2)						\
 	({								\
 		int __err;						\
-		unsigned long long __val = native_read_msr_safe(msr, &__err);\
-		(*p1) = __val;						\
-		(*p2) = __val >> 32;					\
+		u64 __val = native_read_msr_safe(msr, &__err);		\
+		(*p1) = (u32)__val;					\
+		(*p2) = (u32)(__val >> 32);				\
 		__err;							\
 	})
 
 #define rdtscl(low)						\
-	do {							\
-		(low) = native_read_tsc();			\
-	} while(0)
+	((low) = (u32)native_read_tsc())
 
-#define rdtscll(val) ((val) = native_read_tsc())
+#define rdtscll(val)						\
+	((val) = native_read_tsc())
 
 #define write_tsc(val1,val2) wrmsr(0x10, val1, val2)
 
 #define rdpmc(counter,low,high)					\
 	do {							\
 		u64 _l = native_read_pmc();			\
-		low = (u32)_l;					\
-		high = _l >> 32;				\
+		(low)  = (u32)_l;				\
+		(high) = (u32)(_l >> 32);			\
 	} while(0)
 #endif	/* !CONFIG_PARAVIRT */
 
-- 
1.5.1.3

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