[Crash-utility] increase __PHYSICAL_MASK_SHIFT_XEN?

[Jiri Bohac]

Hi Lianbo,

> It's time to update the physical mask for xen, but can you help to
> test the address translation via some command such as vtop, ptov,
> etc? 

you mean with that dump where crash previously failed? Sure. This is the patch
I applied on top of the current git:

--- a/defs.h
+++ b/defs.h
@@ -3583,7 +3583,7 @@ struct arm64_stackframe {
  *  PHYSICAL_PAGE_MASK changed (enlarged) between 2.4 and 2.6, so
  *  for safety, use the 2.6 values to generate it.
  */ 
-#define __PHYSICAL_MASK_SHIFT_XEN     40
+#define __PHYSICAL_MASK_SHIFT_XEN     52
 #define __PHYSICAL_MASK_SHIFT_2_6     46
 #define __PHYSICAL_MASK_SHIFT_5LEVEL  52
 #define __PHYSICAL_MASK_SHIFT  (machdep->machspec->physical_mask_shift)


I can open the dump now:

	$./crash vmcore vmlinux-4.12.14-122.32-default vmlinux-4.12.14-122.32-default.debug
	crash 7.2.9++
	Copyright (C) 2002-2020  Red Hat, Inc.
	...
	      KERNEL: vmlinux-4.12.14-122.32-default
	DEBUG KERNEL: vmlinux-4.12.14-122.32-default.debug
	    DUMPFILE: vmcore  [PARTIAL DUMP]
		CPUS: 8 [OFFLINE: 7]
		DATE: Wed Sep  9 10:16:38 CEST 2020
	      UPTIME: 00:28:41
	LOAD AVERAGE: 0.03, 0.05, 0.07
	       TASKS: 228
	    NODENAME: rsa1419
	     RELEASE: 4.12.14-122.32-default
	     VERSION: #1 SMP Wed Aug 5 12:59:08 UTC 2020 (477c426)
	     MACHINE: x86_64  (2194 Mhz)
	      MEMORY: 16 GB
	       PANIC: "sysrq: SysRq : Trigger a crash"
		 PID: 7401
	     COMMAND: "bash"
		TASK: ffff8804590bc200  [THREAD_INFO: ffff8804590bc200]
		 CPU: 4
	       STATE: TASK_RUNNING (SYSRQ)

	crash> p &jiffies
	$2 = (volatile unsigned long *) 0xffffffff82005000 <jiffies_64>
	crash> vtop  0xffffffff82005000
	VIRTUAL           PHYSICAL        
	ffffffff82005000  2005000         

	PGD DIRECTORY: ffffffff8200a000
	PAGE DIRECTORY: 3003a00e067 [machine]
		PGD: 200e000
	   PUD: 200eff0 => 3003a00f067 [machine]
		PUD: 200f000
	   PMD: 200f080 => 3003b2d5067 [machine]
	   PMD: 32d5000
	   PTE: 32d5028 => 801003003a005067 [machine]
	   PTE: 2005067
	  PAGE: 3003a005000 [machine]
	  PAGE: 2005000

	  PTE    PHYSICAL  FLAGS
	2005067   2005000  (PRESENT|RW|USER|ACCESSED|DIRTY)

	      PAGE        PHYSICAL      MAPPING       INDEX CNT FLAGS
	ffffea0000080140   2005000                0        0  1 fffffc0000800 reserved
	crash> ptov 2005000
	VIRTUAL           PHYSICAL        
	ffff880002005000  2005000         


> Or follow up the 5-level page changes to check if it has the
> capability(cr4 & CR4_LA57)?

sorry, I don't understand what you mean; the crashed linux dump contains an oops that shows the CR4 value as
0000000000040660, i.e. the LA57 bit is not set.

Let me know if you want me to try something else.

Thanks,

-- 
Jiri Bohac <jbohac at suse.cz>
SUSE Labs, Prague, Czechia