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MCE: Fix vm86 handling for 32bit mce handler

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commit a129a7c845 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.

[ Backport to 3.0 notes:
Things changed there slightly:
   - move mce_get_rip() up. It fills up m->cs and m->ip values which
     are evaluated in mce_severity(). Therefore move it up right before
     the mce_severity call. This seem to be another bug in 3.0?
   - Place the backport (fix m->cs in V86 case) to where m->cs gets
     filled which is mce_get_rip() in 3.0
]

Signed-off-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Thomas Renninger <trenn@suse.de>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Andi Kleen
2010-11-19 13:16:22 +01:00
committed by Greg Kroah-Hartman
parent ca465bac8c
commit 8ef8fa7479
1 changed files with 8 additions and 1 deletions
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9
arch/x86/kernel/cpu/mcheck/mce.c
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@@ -451,6 +451,13 @@ static inline void mce_get_rip(struct mce *m, struct pt_regs *regs)
if (regs && (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;
} else {
m->ip = 0;
m->cs = 0;
@@ -988,6 +995,7 @@ void do_machine_check(struct pt_regs *regs, long error_code)
*/
add_taint(TAINT_MACHINE_CHECK);
mce_get_rip(&m, regs);
severity = mce_severity(&m, tolerant, NULL);
/*
@@ -1026,7 +1034,6 @@ void do_machine_check(struct pt_regs *regs, long error_code)
if (severity == MCE_AO_SEVERITY && mce_usable_address(&m))
mce_ring_add(m.addr >> PAGE_SHIFT);
mce_get_rip(&m, regs);
mce_log(&m);
if (severity > worst) {