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 -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html