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authorSteven Rostedt <rostedt@goodmis.org>2015-02-27 14:50:19 -0500
committerSasha Levin <sasha.levin@oracle.com>2015-10-28 16:20:25 -0400
commit4534a1c432551e5588955a5eb8f6cb26c69b047f (patch)
parent4f1a98a2e0cabac1ddcd9aa83cec37526a545bac (diff)
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 <rostedt@goodmis.org> Acked-by: Andy Lutomirski <luto@amacapital.net> Cc: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: http://lkml.kernel.org/r/20150227145019.2bdd4354@gandalf.local.home Signed-off-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
1 files changed, 6 insertions, 0 deletions
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)
+ /*
+ * Initialize the CR4 shadow before doing anything that could
+ * try to read it.
+ */
+ cr4_init_shadow();
printk(KERN_INFO "Initializing CPU#%d\n", cpu);