Re: [Crash-utility] kernel module parsing failure - mips
On Sun, Dec 4, 2016 at 8:16 AM, Rabin Vincent <rabin(a)rab.in> wrote:
On Sun, Dec 04, 2016 at 07:10:38AM -0800, Sagar Borikar wrote:
> <readmem: 806d2c68, KVADDR, "modules", 4, (FOE), 868e5ec>
> <read_kdump: addr: 806d2c68 paddr: 6d2c68 cnt: 4>
> read_netdump: addr: 806d2c68 paddr: 6d2c68 cnt: 4 offset: 5dac68
> GETBUF(416 -> 0)
>
please wait... (gathering module symbol data)module: c0bc9cc0
> <readmem: c0bc9cc0, KVADDR, "module struct", 416, (ROE|Q), 86b25e0>
> <readmem: 82c30000, KVADDR, "pgd page", 16384, (FOE), 948a2a0>
> <read_kdump: addr: 82c30000 paddr: 2c30000 cnt: 16384>
> read_netdump: addr: 82c30000 paddr: 2c30000 cnt: 16384 offset: 31f8000
> <readmem: 3018000, PHYSADDR, "page table", 16384, (FOE), 948e2a8>
> <read_kdump: addr: 3018000 paddr: 3018000 cnt: 16384>
> read_netdump: addr: 0 paddr: 3018000 cnt: 16384 offset: 35e0000
> <read_kdump: addr: c0bc9cc0 paddr: 271e9cc0 cnt: 416>
> read_netdump: READ_ERROR: offset not found for paddr: 271e9cc0
>
> crash: read error: kernel virtual address: c0bc9cc0 type: "module struct"
Here's the error. Either 271e9cc0 is a valid physical address and the dump is
incomplete, or it's not and the page table translation is returning a bogus
physical address for c0bc9cc0.
crash> vtop c0bc9cc0
VIRTUAL PHYSICAL
c0bc9cc0 271e9cc0
SEGMENT: ksseg
PAGE DIRECTORY: 82c30000
PGD: 82c300c0 => 83018000
PTE: 03018bc8 => 271e87cf
PAGE: 271e8000
PTE PHYSICAL FLAGS
271e87cf 271e8000 (PRESENT|WRITE|ACCESSED|MODIFIED|GLOBAL|VALID|DIRTY)
PAGE PHYSICAL MAPPING INDEX CNT FLAGS
82dc0f40 271e8000 0 0 1 40000000
0x271e9cc0 is a valid address but it belongs to high mem(0x20000000
onwards for this platform). Also I don't think there is any problem in
dump as I have done several testing of crash without modules and every
time I have got correct result.
Are you accounting for high memory?
To check the page table translation, use "vtop <addr>" (example below)
to see how crash comes to its result. You'll have to then manually walk
the page tables for this particular virtual address and verify that the
correct PGD and PTE entries are being read. It could be easier if use
vmalloc_to_page() and page_address() first in your kernel to print out
the correct physical address for some known vmalloc'd address.
As the driver works fine, I think kernel translation looks ok. Wrong
physical address translation would have failed the nvme driver to run.
Stress testing with the driver is fine. But still would go through the
PTE entries.
Dave,
crash> sym -n swapper_pg_dir
806d0000 (B) swapper_pg_dir
806d1000 (B) invalid_pte_table
crash>
What does the command above on your kernel show?
crash> sym -n swapper_pg_dir
82c30000 (B) swapper_pg_dir
82c34000 (B) invalid_pte_table
Thanks
Sagar
crash> vtop c01050c0
VIRTUAL PHYSICAL
c01050c0 71550c0
SEGMENT: ksseg
PAGE DIRECTORY: 80540000
PGD: 805400c0 => 872b0000
PTE: 072b0104 => 071545ef
PAGE: 07154000
PTE PHYSICAL FLAGS
71545ef 7154000 (PRESENT|READ|WRITE|ACCESSED|MODIFIED|GLOBAL|VALID|NO_READ|DIRTY)
PAGE PHYSICAL MAPPING INDEX CNT FLAGS
81038e60 7154000 0 0 1 40000000
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