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Groups > linux.kernel > #1492931

[PATCH 1/3] x86/init: Fix cr4_init_shadow() on CR4-less machines

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

Cc: stable@vger.kernel.org
Reported-by: david@saggiorato.net
Fixes: 1e02ce4cccdc ("x86: Store a per-cpu shadow copy of CR4")
Signed-off-by: Andy Lutomirski <luto@kernel.org>
---
 arch/x86/include/asm/tlbflush.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/tlbflush.h b/arch/x86/include/asm/tlbflush.h
index 6fa85944af83..dee8a70382ba 100644
--- a/arch/x86/include/asm/tlbflush.h
+++ b/arch/x86/include/asm/tlbflush.h
@@ -81,7 +81,7 @@ DECLARE_PER_CPU_SHARED_ALIGNED(struct tlb_state, cpu_tlbstate);
 /* 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. */
-- 
2.7.4

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Thread

[PATCH 0/3] CR4 fixes (some are urgent) Andy Lutomirski <luto@kernel.org> - 2016-09-28 21:40 +0200
  [PATCH 2/3] x86/boot: Fix another __read_cr4() case on 486 Andy Lutomirski <luto@kernel.org> - 2016-09-28 21:40 +0200
    Re: [PATCH 2/3] x86/boot: Fix another __read_cr4() case on 486 Borislav Petkov <bp@alien8.de> - 2016-09-29 13:50 +0200
      Re: [PATCH 2/3] x86/boot: Fix another __read_cr4() case on 486 Andy Lutomirski <luto@amacapital.net> - 2016-09-29 21:10 +0200
  [PATCH 3/3] x86/asm: Get rid of __read_cr4_safe() Andy Lutomirski <luto@kernel.org> - 2016-09-28 21:40 +0200
  [PATCH 1/3] x86/init: Fix cr4_init_shadow() on CR4-less machines Andy Lutomirski <luto@kernel.org> - 2016-09-28 21:40 +0200
    Re: [PATCH 1/3] x86/init: Fix cr4_init_shadow() on CR4-less machines Borislav Petkov <bp@alien8.de> - 2016-09-29 13:50 +0200
    [tip:x86/urgent] x86/init: Fix cr4_init_shadow() on CR4-less  machines tip-bot for Andy Lutomirski <tipbot@zytor.com> - 2016-09-29 20:30 +0200

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