add memory clobber to ins{b,w,l}

Change-Id: Ia710eb59f23a52afba2a8ef6e0ff2b2306107245
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Reviewed-on: http://review.coreboot.org/4033
Tested-by: build bot (Jenkins)
Reviewed-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-by: Patrick Georgi <patrick@georgi-clan.de>

src/arch/x86/include/arch/io.h

@@ -113,6 +113,7 @@ static inline void insb(uint16_t port, void *addr, unsigned long count)
 		"cld ; rep ; insb "
 		: "=D" (addr), "=c" (count)
 		: "d"(port), "0"(addr), "1" (count)
+		: "memory"
 		);
 }
 
@@ -122,6 +123,7 @@ static inline void insw(uint16_t port, void *addr, unsigned long count)
 		"cld ; rep ; insw "
 		: "=D" (addr), "=c" (count)
 		: "d"(port), "0"(addr), "1" (count)
+		: "memory"
 		);
 }
 
@@ -131,6 +133,7 @@ static inline void insl(uint16_t port, void *addr, unsigned long count)
 		"cld ; rep ; insl "
 		: "=D" (addr), "=c" (count)
 		: "d"(port), "0"(addr), "1" (count)
+		: "memory"
 		);
 }