x86: mark read_crX() asm code as volatile
authorKirill Korotaev <dev@openvz.org>
Wed, 17 Oct 2007 16:04:33 +0000 (18:04 +0200)
committerThomas Gleixner <tglx@inhelltoy.tec.linutronix.de>
Wed, 17 Oct 2007 18:15:31 +0000 (20:15 +0200)
commitc1217a75ea102d4e69321f210fab60bc47b9a48e
treefffa575916b27bac17dfb751300ed2e1f9107f0c
parentf891dd18c107d582c3ab98da5209c930e16baf78
x86: mark read_crX() asm code as volatile

Some gcc versions (I checked at least 4.1.1 from RHEL5 & 4.1.2 from gentoo)
can generate incorrect code with read_crX()/write_crX() functions mix up,
due to cached results of read_crX().

The small app for x8664 below compiled with -O2 demonstrates this
(i686 does the same thing):
include/asm-x86/system_32.h
include/asm-x86/system_64.h