From 4534a1c432551e5588955a5eb8f6cb26c69b047f Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Fri, 27 Feb 2015 14:50:19 -0500 Subject: x86: Init per-cpu shadow copy of CR4 on 32-bit CPUs too [ Upstream commit 5b2bdbc84556774afbe11bcfd24c2f6411cfa92b ] Commit: 1e02ce4cccdc ("x86: Store a per-cpu shadow copy of CR4") added a shadow CR4 such that reads and writes that do not modify the CR4 execute much faster than always reading the register itself. The change modified cpu_init() in common.c, so that the shadow CR4 gets initialized before anything uses it. Unfortunately, there's two cpu_init()s in common.c. There's one for 64-bit and one for 32-bit. The commit only added the shadow init to the 64-bit path, but the 32-bit path needs the init too. Link: http://lkml.kernel.org/r/20150227125208.71c36402@gandalf.local.home Fixes: 1e02ce4cccdc "x86: Store a per-cpu shadow copy of CR4" Signed-off-by: Steven Rostedt Acked-by: Andy Lutomirski Cc: Peter Zijlstra (Intel) Cc: Linus Torvalds Link: http://lkml.kernel.org/r/20150227145019.2bdd4354@gandalf.local.home Signed-off-by: Ingo Molnar Signed-off-by: Sasha Levin --- arch/x86/kernel/cpu/common.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index e757fcbe90db..88635b301694 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -1405,6 +1405,12 @@ void cpu_init(void) wait_for_master_cpu(cpu); + /* + * Initialize the CR4 shadow before doing anything that could + * try to read it. + */ + cr4_init_shadow(); + show_ucode_info_early(); printk(KERN_INFO "Initializing CPU#%d\n", cpu); -- cgit v1.2.3