> -----Original Message----- > From: owner-freebsd-hack...@freebsd.org > [mailto:owner-freebsd-hack...@freebsd.org] On Behalf Of Andriy Gapon > Sent: Wednesday, November 11, 2015 3:02 AM > To: John Baldwin <j...@freebsd.org> > Cc: Hans Petter Selasky <h...@selasky.org>; FreeBSD Hackers > <freebsd-hack...@freebsd.org>; freebsd-current@FreeBSD.org > Subject: Re: strange kernel crash > > On 10/11/2015 20:42, John Baldwin wrote: > > On Tuesday, November 10, 2015 10:48:08 AM Andriy Gapon wrote: > >> On 09/11/2015 22:16, John Baldwin wrote: > >>> On Friday, November 06, 2015 07:02:59 PM Hans Petter Selasky wrote: > >>>> On 11/06/15 12:20, Andriy Gapon wrote: > >>>>> Now the strange part: > >>>>> > >>>>> 0xffffffff80619a18 <+744>: jne 0xffffffff80619a61 > >>>>> <__mtx_lock_flags+817> > >>>>> 0xffffffff80619a1a <+746>: mov %rbx,(%rsp) > >>>>> => 0xffffffff80619a1e <+750>: movq $0x0,0x18(%rsp) > >>>>> 0xffffffff80619a27 <+759>: movq $0x0,0x10(%rsp) > >>>>> 0xffffffff80619a30 <+768>: movq $0x0,0x8(%rsp) > >>>> > >>>> Were these instructions dumped from RAM or from the kernel ELF file? > >>> > >>> Probably not from RAM. You can use 'info files' in gdb to see what > >>> is handling the address range in question (core vs executable). x/i > >>> in ddb would have been the "real" truth. > >> > >> Yes, according to the output of files it looks like gdb would read > >> that data from the text section of the kernel file. > >> > >> How about libkvm? Would kvm_read read data from the core file? > > > > kvm_read should only access the vmcore, yes. > > > >> I've written the following small program (cut down dmesg.c, actually): > >> https://people.freebsd.org/~avg/vmcore_read.c > >> > >> (kgdb) disassemble /r > >> => 0xffffffff80619a1e <+750>: 48 c7 44 24 18 00 00 00 00 movq > >> $0x0,0x18(%rsp) > >> > >> $ vmcore_read -N /boot/kernel.29/kernel -M /var/crash/vmcore.29 > >> 0xffffffff80619a1e 9 > >> 48 c7 44 24 18 00 00 00 00 > >> > >> Seems like the code is intact. > >> > >> P.S. > >> 1. To correct something I said earlier, the fault is #UD, not #GP. > >> 2. The only "suspicious" activity at the time of the crash was the > >> execution of a bhyve VM. > > > > Was the crash in the guest or the host? UD# seems even more bizarre. > > It was the host. This is bizarre indeed. I can think only of two > possibilities: > - new CPU erratum > - corrupted data somehow getting into the instruction cache, but the > correct data being read during the crash dump (i.e. flaky memory)
Or perhaps a missing memory sync operation somewhere.... > > -- > Andriy Gapon > _______________________________________________ > freebsd-hack...@freebsd.org mailing list > https://lists.freebsd.org/mailman/listinfo/freebsd-hackers > To unsubscribe, send any mail to "freebsd-hackers-unsubscr...@freebsd.org" _______________________________________________ firstname.lastname@example.org mailing list https://lists.freebsd.org/mailman/listinfo/freebsd-current To unsubscribe, send any mail to "freebsd-current-unsubscr...@freebsd.org"