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Patch "x86/init: Fix cr4_init_shadow() on CR4-less machines" has been added to the 4.4-stable tree

PATCH [email protected] 1 participant 1 message Oct 4, 2016

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This is a note to let you know that I've just added the patch titled

x86/init: Fix cr4_init_shadow() on CR4-less machines

to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:

     x86-init-fix-cr4_init_shadow-on-cr4-less-machines.patch

and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

Quoted 1 line

From e1bfc11c5a6f40222a698a818dc269113245820e Mon Sep 17 00:00:00 2001

From: Andy Lutomirski <[email protected]>
Date: Wed, 28 Sep 2016 12:34:14 -0700
Subject: x86/init: Fix cr4_init_shadow() on CR4-less machines

From: Andy Lutomirski <[email protected]>

commit e1bfc11c5a6f40222a698a818dc269113245820e upstream.

cr4_init_shadow() will panic on 486-like machines without CR4. Fix it using __read_cr4_safe().

Reported-by [email protected]
Signed-off-by Andy Lutomirski <[email protected]>
Reviewed-by Borislav Petkov <[email protected]>
Cc Borislav Petkov <[email protected]>
Cc Brian Gerst <[email protected]>
Cc Denys Vlasenko <[email protected]>
Cc H. Peter Anvin <[email protected]>
Cc Josh Poimboeuf <[email protected]>
Cc Linus Torvalds <[email protected]>
Cc Peter Zijlstra <[email protected]>
Cc Thomas Gleixner <[email protected]>
Fixes 1e02ce4cccdc ("x86: Store a per-cpu shadow copy of CR4")
Link http://lkml.kernel.org/r/43a20f81fb504013bf613913dc25574b45336a61.1475091074.git.luto@kernel.org open here
Signed-off-by Ingo Molnar <[email protected]>
Signed-off-by Greg Kroah-Hartman <[email protected]>
---
 arch/x86/include/asm/tlbflush.h |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
arch/x86/include/asm/tlbflush.h +1 -1
@@ -32,7 +32,7 @@ DECLARE_PER_CPU_SHARED_ALIGNED(struct tl
 /* Initialize cr4 shadow for this CPU. */
 static inline void cr4_init_shadow(void)
 {
-	this_cpu_write(cpu_tlbstate.cr4, __read_cr4());
+	this_cpu_write(cpu_tlbstate.cr4, __read_cr4_safe());
 }
 
 /* Set in this cpu's CR4. */

Patches currently in stable-queue which might be from [email protected] are

queue-4.4/x86-init-fix-cr4_init_shadow-on-cr4-less-machines.patch queue-4.4/x86-boot-initialize-fpu-and-x86_feature_always-even-if-we-don-t-have-cpuid.patch