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Groups > linux.kernel > #1293356
| From | Jeff Merkey <linux.mdb@gmail.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: 4.4-rc5 Setting trap flag inside nmi handler results in HARD LOCKUP |
| Date | 2015-12-16 22:50 +0100 |
| Message-ID | <qGs7n-7dW-1@gated-at.bofh.it> (permalink) |
| References | <qGoQb-5f3-51@gated-at.bofh.it> <qGpjc-5qi-7@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
He is stepping into native_safe_halt() when this bug occurs (processor has halted). I am starting to wonder is this is a linux bug or intel bug. I am starting to lean towards intel bug possibly. I will go and review intels documentation about what happens when a processor has been halted, is triggered with an NMI, then someone reloads the processor with the trap flag set then returns to a hlt instruction. Wow, this fucking cool .. I can debug Linus' "I halt when idle" core function in the linux scheduler. On 12/16/15, Jeff Merkey <linux.mdb@gmail.com> wrote: > 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 > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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4.4-rc5 Setting trap flag inside nmi handler results in HARD LOCKUP Jeff Merkey <linux.mdb@gmail.com> - 2015-12-16 19:20 +0100
Re: 4.4-rc5 Setting trap flag inside nmi handler results in HARD LOCKUP Jeff Merkey <linux.mdb@gmail.com> - 2015-12-16 19:50 +0100
Re: 4.4-rc5 Setting trap flag inside nmi handler results in HARD LOCKUP Jeff Merkey <linux.mdb@gmail.com> - 2015-12-16 22:50 +0100
Re: 4.4-rc5 Setting trap flag inside nmi handler results in HARD LOCKUP Jeff Merkey <linux.mdb@gmail.com> - 2015-12-16 23:10 +0100
Re: 4.4-rc5 Setting trap flag inside nmi handler results in HARD LOCKUP Jeff Merkey <linux.mdb@gmail.com> - 2015-12-17 08:30 +0100
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