From: Andi Kleen <andi@xxxxxxxxxxxxxx>
-------------------
This is a commit scheduled for the next v2.6.34 longterm release.
http://git.kernel.org/?p=linux/kernel/git/paulg/longterm-queue-2.6.34.git
If you see a problem with using this for longterm, please comment.
-------------------
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.
[ 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@xxxxxxxxxxxxxxx>
Signed-off-by: Tony Luck <tony.luck@xxxxxxxxx>
Signed-off-by: Thomas Renninger <trenn@xxxxxxx>
Reviewed-by: Tony Luck <tony.luck@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
[PG: commit 8ef8fa7479fff9313387b873413f5ae233a2bd04 in v3.0.44]
Signed-off-by: Paul Gortmaker <paul.gortmaker@xxxxxxxxxxxxx>
---
arch/x86/kernel/cpu/mcheck/mce.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kernel/cpu/mcheck/mce.c b/arch/x86/kernel/cpu/mcheck/mce.c
index 8a6f0afa767e..84b313c1297e 100644
--- a/arch/x86/kernel/cpu/mcheck/mce.c
+++ b/arch/x86/kernel/cpu/mcheck/mce.c
@@ -453,6 +453,13 @@ 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;
@@ -990,6 +997,7 @@ 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);
/*
@@ -1028,7 +1036,6 @@ 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) {
--
1.8.5.2
--
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