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Message-Id: <20120527010436.725850474@linuxfoundation.org>
Date: Sun, 27 May 2012 10:05:55 +0900
From: Greg KH <gregkh@...uxfoundation.org>
To: linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc: torvalds@...ux-foundation.org, akpm@...ux-foundation.org,
alan@...rguk.ukuu.org.uk, Andi Kleen <ak@...ux.intel.com>,
Tony Luck <tony.luck@...el.com>
Subject: [ 92/94] MCE: Fix vm86 handling for 32bit mce handler
3.3-stable review patch. If anyone has any objections, please let me know.
------------------
From: Andi Kleen <andi@...stfloor.org>
commit a129a7c84582629741e5fa6f40026efcd7a65bd4 upstream.
When running on 32bit the mce handler could misinterpret
vm86 mode as ring 0. This can affect whether it does recovery
or not; it was possible to panic when recovery was actually
possible.
Fix this by always forcing vm86 to look like ring 3.
Signed-off-by: Andi Kleen <ak@...ux.intel.com>
Signed-off-by: Tony Luck <tony.luck@...el.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
arch/x86/kernel/cpu/mcheck/mce.c | 8 ++++++++
1 file changed, 8 insertions(+)
--- a/arch/x86/kernel/cpu/mcheck/mce.c
+++ b/arch/x86/kernel/cpu/mcheck/mce.c
@@ -437,6 +437,14 @@ static inline void mce_gather_info(struc
if (m->mcgstatus & (MCG_STATUS_RIPV|MCG_STATUS_EIPV)) {
m->ip = regs->ip;
m->cs = regs->cs;
+
+ /*
+ * When in VM86 mode make the cs look like ring 3
+ * always. This is a lie, but it's better than passing
+ * the additional vm86 bit around everywhere.
+ */
+ if (v8086_mode(regs))
+ m->cs |= 3;
}
/* Use accurate RIP reporting if available. */
if (rip_msr)
--
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