| From | Greg Kroah-Hartman <> | Subject | [PATCH 4.7 007/141] x86/init: Fix cr4_init_shadow() on CR4-less machines | Date | Thu, 6 Oct 2016 10:27:23 +0200 |
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4.7-stable review patch. If anyone has any objections, please let me know.
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From: Andy Lutomirski <luto@kernel.org>
commit e1bfc11c5a6f40222a698a818dc269113245820e upstream.
cr4_init_shadow() will panic on 486-like machines without CR4. Fix it using __read_cr4_safe().
Reported-by: david@saggiorato.net Signed-off-by: Andy Lutomirski <luto@kernel.org> Reviewed-by: Borislav Petkov <bp@suse.de> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Fixes: 1e02ce4cccdc ("x86: Store a per-cpu shadow copy of CR4") Link: http://lkml.kernel.org/r/43a20f81fb504013bf613913dc25574b45336a61.1475091074.git.luto@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- arch/x86/include/asm/tlbflush.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/arch/x86/include/asm/tlbflush.h +++ b/arch/x86/include/asm/tlbflush.h @@ -81,7 +81,7 @@ 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. */
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