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

From: Michael Gmelin <freebsd_at_grem.de>
Date: Mon, 4 Jun 2018 23:17:56 +0200
On Mon, 4 Jun 2018 14:06:55 +0300
Konstantin Belousov <kostikbel_at_gmail.com> wrote:

> On Mon, Jun 04, 2018 at 12:46:32AM +0200, Michael Gmelin wrote:
> > 
> > 
> > On Sun, 3 Jun 2018 23:53:40 +0300
> > Konstantin Belousov <kostikbel_at_gmail.com> wrote:
> >   
> > > On Sun, Jun 03, 2018 at 09:50:20PM +0200, Michael Gmelin wrote:  
> > > > 
> > > > 
> > > > On Sun, 3 Jun 2018 18:04:23 +0300
> > > > Konstantin Belousov <kostikbel_at_gmail.com> wrote:
> > > >     
> > > > > 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 _at_ 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.    
> > > > 
> > > > Okay, according to kgbd this should be here:
> > > > 
> > > > https://svnweb.freebsd.org/base/head/sys/amd64/amd64/mp_machdep.c?revision=333368&view=markup#l369
> > > > 
> > > > 364
> > > > 365    /* Create the initial 1GB replicated page tables */
> > > > 366    for (i = 0; i < 512; i++) {
> > > > 367            /* Each slot of the level 4 pages points to the
> > > > same level 3 page */ 368            pt4[i] =
> > > > (u_int64_t)(uintptr_t)(mptramp_pagetables + PAGE_SIZE); 369
> > > > pt4[i] |= PG_V | PG_RW | PG_U; 370
> > > > 371            /* Each slot of the level 3 pages points to the
> > > > same level 2 page */ 372            pt3[i] =
> > > > (u_int64_t)(uintptr_t)(mptramp_pagetables + (2 * PAGE_SIZE));
> > > > 373            pt3[i] |= PG_V | PG_RW | PG_U; 374
> > > > 375            /* The level 2 page slots are mapped with 2MB
> > > > pages for 1GB. */ 376            pt2[i] = i * (2 * 1024 * 1024);
> > > > 377            pt2[i] |= PG_V | PG_RW | PG_PS | PG_U;
> > > > 378    }
> > > > 
> > > > -m    
> > > You have fault on write due to read-only mapping of the portion of
> > > the direct map, which maps the kernel text.  It is consistent with
> > > the faulting address.  It is not clear if it is something new on
> > > your machine, or before the kernel text was silently corrupted,
> > > since ro protection is somewhat recent.
> > > 
> > > It seems that mp_bootaddress() selected the bad place for the
> > > bootstrap page tables. Even more, we do not include the kernel
> > > text into the physmem[] array, so it is not clear how did it
> > > happen. This code was also changed recently.
> > > 
> > > Can you add the print of the physmap[] array somewhere before the
> > > panic, to see what is the kernel idea of the available memory ?
> > > It should be already done if you have serial console and set
> > > debug.late_console tunable to 0.  
> > 
> > This is a sad little machine without any kind of serial console.
> > 
> > Physmap looks like this after calling getmemsize():
> > 
> > [0]: 0x10000
> > [1]: 0x30000
> > [2]: 0x40000
> > [3]: 0x9e000
> > [4]: 0x100000
> > [5]: 0xf00000
> > [6]: 0x1003000
> > [7]: 0x7bf7a000
> > 
> > Physical memory chunks logged in cpu_startup are:
> > 
> > 0x0000000000010000 - 0x000000000002ffff, 141072 bytes (32 pages)
> > 0x0000000000040000 - 0x000000000009dfff, 385024 bytes (94 pages)  
> These two chunks reports are consistent with the physmap[0-1, 2-3].
> 
> > 0x0000000000100000 - 0x00000000001fffff, 1048576 bytes (256 pages)
> > 0x0000000002c00000 - 0x0000000075467fff, 1921417216 bytes (469096
> > pages) 0x0000000100000000 - 0x00000001005e7fff, 6193152 bytes (1512
> > pages)  
> But these three looks completely unrelated to the rest of the physmap,
> perhaps except the physmap[4].  We allocate boot pages from the top
> of the last physmap chunk, but I am certain that we do not consume
> that much memory for boot to make physmap[7] from the last reported
> address.
> 
> Are you sure that there are no typos  in the values above ?

Double checked the numbers. I changed it a bit more,
so that debug output appears all on one page. Please see here for the
results:

https://gist.github.com/grembo/cebb9f7e2a98c37a51bee1e508f7d890

This is how I generated the output:

Index: sys/amd64/amd64/machdep.c
===================================================================
--- sys/amd64/amd64/machdep.c	(revision 333992)
+++ sys/amd64/amd64/machdep.c	(working copy)
_at__at_ -1215,7 +1215,7 _at__at_
  * XXX first should be vm_paddr_t.
  */
 static void
-getmemsize(caddr_t kmdp, u_int64_t first)
+getmemsize(caddr_t kmdp, u_int64_t first, int* physmap_idx_out, vm_paddr_t* physmap_out)
 {
 	int i, physmap_idx, pa_indx, da_indx;
 	vm_paddr_t pa, physmap[PHYSMAP_SIZE];
_at__at_ -1482,6 +1482,10 _at__at_
 
 	/* Map the message buffer. */
 	msgbufp = (struct msgbuf *)PHYS_TO_DMAP(phys_avail[pa_indx]);
+
+	*physmap_idx_out = physmap_idx;
+	for (int i=0; i<physmap_idx; ++i)
+	  physmap_out[i] = physmap[i];
 }
 
 static caddr_t
_at__at_ -1553,6 +1557,8 _at__at_
 	char *env;
 	size_t kstack0_sz;
 	int late_console;
+	int physmap_idx;
+	vm_paddr_t physmap[PHYSMAP_SIZE];
 
 	TSRAW(&thread0, TS_ENTER, __func__, NULL);
 
_at__at_ -1759,7 +1765,7 _at__at_
 		amd64_kdb_init();
 	}
 
-	getmemsize(kmdp, physfree);
+	getmemsize(kmdp, physfree, &physmap_idx, &physmap[0]);
 	init_param2(physmem);
 
 	/* now running on new page tables, configured,and u/iom is accessible */
_at__at_ -1767,6 +1773,22 _at__at_
 	if (late_console)
 		cninit();
 
+	printf("Physmap index: %i\n", physmap_idx);
+	for (int i=0; i<physmap_idx; ++i)
+	  printf("Physmap %i: 0x%016jx\n", i, (uintmax_t)physmap[i]);
+	printf("---------\n");
+
+	for (int i = 0; phys_avail[i + 1] != 0; i += 2) {
+		vm_paddr_t size;
+
+		size = phys_avail[i + 1] - phys_avail[i];
+		printf(
+			"0x%016jx - 0x%016jx, %ju bytes (%ju pages)\n",
+			(uintmax_t)phys_avail[i],
+			(uintmax_t)phys_avail[i + 1] - 1,
+			(uintmax_t)size, (uintmax_t)size / PAGE_SIZE);
+	}
+
 #ifdef DEV_ISA
 #ifdef DEV_ATPIC
 	elcr_probe();


-m

-- 
Michael Gmelin

-- 
Michael Gmelin
Received on Mon Jun 04 2018 - 19:18:07 UTC

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