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From: Andy Lutomirski <luto@kernel.org>
To: x86@kernel.org
Cc: david@saggiorato.net, Borislav Petkov <bp@alien8.de>,
	Brian Gerst <brgerst@gmail.com>,
	linux-kernel@vger.kernel.org, Andy Lutomirski <luto@kernel.org>,
	stable@vger.kernel.org
Subject: [PATCH 1/3] x86/init: Fix cr4_init_shadow() on CR4-less machines
Date: Wed, 28 Sep 2016 12:34:14 -0700
Message-ID: <43a20f81fb504013bf613913dc25574b45336a61.1475091074.git.luto@kernel.org> (raw)
In-Reply-To: <cover.1475091074.git.luto@kernel.org>
In-Reply-To: <cover.1475091074.git.luto@kernel.org>

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

  reply index

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-09-28 19:34 [PATCH 0/3] CR4 fixes (some are urgent) Andy Lutomirski
2016-09-28 19:34 ` Andy Lutomirski [this message]
2016-09-29 11:44   ` [PATCH 1/3] x86/init: Fix cr4_init_shadow() on CR4-less machines Borislav Petkov
2016-09-29 18:21   ` [tip:x86/urgent] " tip-bot for Andy Lutomirski
2016-09-28 19:34 ` [PATCH 2/3] x86/boot: Fix another __read_cr4() case on 486 Andy Lutomirski
2016-09-29 11:48   ` Borislav Petkov
2016-09-29 19:09     ` Andy Lutomirski
2016-09-28 19:34 ` [PATCH 3/3] x86/asm: Get rid of __read_cr4_safe() Andy Lutomirski

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