Messages in this thread | | | Date | Wed, 16 Dec 2015 11:42:11 -0700 | Subject | Re: 4.4-rc5 Setting trap flag inside nmi handler results in HARD LOCKUP | From | Jeff Merkey <> |
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On 12/16/15, Jeff Merkey <linux.mdb@gmail.com> wrote: > Setting the (trap flag | resume flag) inside of an nmi handler results > in a hard lockup while setting the resume flag works fine. > > The watchdog detector fails to detect the lockup. I am currently > examining the trap gate and interrupt gate setup on Linux and if > anyone has any ideas it would be nice to be able to debug and step > through the nmi handlers. I got breakpoints to work. I noticed > kgdb/kdb just punts here and refuses to allow someone to step inside > an nmi handler. > > There is no reason Linux should not allow this to work since windows > does and every other OS out there. I have seen this across some rex64 > sysret calls as well this lockup behavior. > > Anyone who is an intel expert with any clues would love some input if > you know about this problem. > > Jeff >
More info. Linux is getting a trap and it looks like the IDT is getting swapped when it gets it -- POW - Dead Linux.
Damn ... Well, it will be long night and lots of builds ...
Jeff
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