Fatal trap 12: page fault on Acer Chromebook 720 (peppy)

[Konstantin Belousov]

On Sun, Jun 03, 2018 at 04:55:00PM +0200, Michael Gmelin wrote:
> 
> 
> On Sun, 3 Jun 2018 16:21:10 +0300
> Konstantin Belousov <kostikbel at gmail.com> wrote:
> 
> > On Sun, Jun 03, 2018 at 02:48:40PM +0200, Michael Gmelin wrote:
> > > Hi,
> > > 
> > > After upgrading CURRENT to r333992 (from something at least a year
> > > old, quite some changes in mp_machdep.c since), this machine crashes
> > > on boot:
> > > 
> > > Copyright (c) 1992-2018 The FreeBSD Project.
> > > Copyright (c) 1979, 1980, 1983, 1986, 1988, 1989, 1991, 1992, 1993,
> > > 1994 The Regents of the University of California. All rights
> > > reserved. FreeBSD is a registered trademark of The FreeBSD
> > > Foundation. FreeBSD 12.0-CURRENT #1 r333992: Tue May 22 00:31:04
> > > CEST 2018 root at flimsy:/usr/obj/usr/src/amd64.amd64/sys/flimsy amd64
> > > FreeBSD clang version 6.0.0 (tags/RELEASE_600/final 326565) (based
> > > on LLVM 6.0.0) WARNING: WITNESS option enabled, expect reduced
> > > performance. VT(vga): resolution 640x480
> > > CPU: Intel(R) Celeron(R) 2955U @ 1.40GHz (1396.80-MHz K8-class CPU)
> > >   Origin="GenuineIntel"  Id=0x40651  Family=0x6  Model=0x45
> > > Stepping=1
> > > Features=0xbfebfbff<FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,
> > > CMOV,PAT,PSE36,CLFLUSH,DTS,ACPI,MMX,FXSR,SSE,SSE2,SS,HTT,TM,PBE>
> > > Features2=0x4ddaebbf<SSE3,PCLMULQDQ,DTES64,MON,DS_CPL,VMX,EST,TM2,SSSE3,SDBG,CX16,
> > > xTPR,PDCM,PCID,SSE4.1,SSE4.2,MOVBE,POPCNT,TSCDLT,XSAVE,OSXSAVE,RDRAND>
> > > AMD Features=0x2c100800<SYSCALL,NX,Page1GB,RDTSCP,LM> AMD
> > > Features2=0x21<LAHF,ABM> Structured Extended
> > > Features=0x2603<FSGSBASE,TSCADJ,ERMS,INVPCID,NFPUSG> XSAVE
> > > Features=0x1<XSAVEOPT> VT-x: (disabled in BIOS)
> > > PAT,HLT,MTF,PAUSE,EPT,UG,VPID TSC: P-state invariant, performance
> > > statistics real memory  = 4301258752 (4102 MB)
> > > avail memory = 1907572736 (1819 MB)
> > > Event timer "LAPIC" quality 600
> > > ACPI APIC Table: <CORE   COREBOOT>  
> > What does this mean ?  Did you flashed coreboot ?
> 
> This machine comes with it by default (my model was delivered with 
> SeaBIOS 20131018_145217-build121-m2). So I didn't flash anything
> (didn't feel like bricking it).
> 
> > 
> > > kernel trap 12 with interrupts disabled
> > > 
> > > Fatal trap 12: page fault while in kernel mode 
> > > cpuid = 0; apic id = 00
> > > fault virtual address    = 0xfffff80001000000
> > > fault code               = supervisor write data, protection
> > > violation instruction pointer      = 0x20:Oxffffffff8102955f
> > > stack pointer            = 0x28:0xffffffff82a79be0
> > > frame pointer            = 0x28:0xffffffff82a79c10
> > > code segment             = base Ox0, limit Oxfffff, type Ox1b
> > >                          = DPL 0, pres 1, long 1, def32 0, gran 1
> > > processor eflags         = resume, IOPL = 0
> > > current process          = 0 ()
> > > [ thread pid 0 tid 0 ]
> > > Stopped at      native_start_all_aps+0x08f:      movq
> > > %rax,(%rsi)  
> > Look up the source line number for this address.
> > 
> 
> I guess that's sys/amd64/amd64/support.S line 854 (in rdmsr), called by
> native_start_all_aps. Any additional hints how I can track it down?
Why did you decided that this is rdmsr_safe() ? First,
native_start_all_aps() does not call rdmsr, second the ddb
report clearly indicates that the fault occured acessing DMAP in
native_start_all_aps().

Just look up the source line by the address native_start_all_aps+0x08f.