11.0-CURRENT r290039 privileged instruction fault while in kernel mode

[Don Lewis]

On 28 Oct, Konstantin Belousov wrote:
> On Tue, Oct 27, 2015 at 04:09:28PM -0700, Don Lewis wrote:
>> I just got this crash while running poudriere on a freshly upgraded
>> 11.0-CURRENT machine.  The instruction pointer value looks pretty
>> strange.
>> 
>> 
>> FreeBSD zipper.catspoiler.org 11.0-CURRENT FreeBSD 11.0-CURRENT #30 r290039: Tue Oct 27 00:08:00 PDT 2015     dl at zipper.catspoiler.org:/usr/obj/usr/src/sys/GENERIC  amd64
>> 
>> panic: 
>> 
>> GNU gdb 6.1.1 [FreeBSD]
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>> 
>> Unread portion of the kernel message buffer:
>> 
>> 
>> Fatal trap 1: privileged instruction fault while in kernel mode
>> cpuid = 4; apic id = 14
>> instruction pointer	= 0x20:0xffffffff8240fef5
> What is the instruction at the reported address ?

(kgdb) disassemble/r
Dump of assembler code for function cpu_lock:
   0xffffffff8240fef0 <+0>:	25 bb 40 82 ff	and    $0xff8240bb,%eax
=> 0xffffffff8240fef5 <+5>:	ff	(bad)  
   0xffffffff8240fef6 <+6>:	ff	(bad)  
   0xffffffff8240fef7 <+7>:	ff 00	incl   (%rax)
   0xffffffff8240fef9 <+9>:	00 71 02	add    %dh,0x2(%rcx)
   0xffffffff8240fefc <+12>:	00 00	add    %al,(%rax)
   0xffffffff8240fefe <+14>:	00 00	add    %al,(%rax)
   0xffffffff8240ff00 <+16>:	00 00	add    %al,(%rax)
   0xffffffff8240ff02 <+18>:	00 00	add    %al,(%rax)
   0xffffffff8240ff04 <+20>:	00 00	add    %al,(%rax)
   0xffffffff8240ff06 <+22>:	00 00	add    %al,(%rax)
   0xffffffff8240ff08 <+24>:	01 00	add    %eax,(%rax)
   0xffffffff8240ff0a <+26>:	00 00	add    %al,(%rax)
   0xffffffff8240ff0c <+28>:	00 00	add    %al,(%rax)
   0xffffffff8240ff0e <+30>:	00 00	add    %al,(%rax)
End of assembler dump.