Re: [Crash-utility] ARM64 (odroid-c2) crash fails to read live kernel
----- Original Message -----
> How is your system configured?
4k pages with 3-level PTE
I did not backport any of the support for deeper level PTE's or larger page
sizes
>You might even be able to get to a crash> prompt by running:
> $ crash /proc/kcore --no_modules
no_modules works like a champ
root@odroid64-pre:~/crash-7.1.4# ./crash /proc/kcore --no_modules
crash 7.1.4
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This GDB was configured as "aarch64-unknown-linux-gnu"...
WARNING: no kernel module access
KERNEL: /lib/modules/3.14.29+/build/vmlinux
DUMPFILE: /proc/kcore
CPUS: 4
DATE: Tue Mar 8 15:15:26 2016
UPTIME: 05:23:46
LOAD AVERAGE: 0.67, 0.36, 0.19
TASKS: 207
NODENAME: odroid64-pre
RELEASE: 3.14.29+
VERSION: #1 SMP PREEMPT Tue Mar 8 01:06:35 CST 2016
MACHINE: aarch64 (unknown Mhz)
MEMORY: 1.9 GB
PID: 8000
COMMAND: "crash"
TASK: ffffffc05c298c00 [THREAD_INFO: ffffffc05857c000]
CPU: 1
STATE: TASK_RUNNING (ACTIVE)
crash>
root@odroid64-pre:~/crash-7.1.4# ./crash /proc/kcore -d8
... [ cut ] ...
<readmem: ffffffc001c27f58, KVADDR, "modules", 8, (FOE),
bb1a88>
<read_proc_kcore: addr: ffffffc001c27f58 paddr: 2c27f58 cnt: 8>
GETBUF(528 -> 0)
module: ffffffbffc081ad0
<readmem: ffffffbffc081ad0, KVADDR, "module struct", 528, (ROE|Q),
c14b08>
<readmem: ffffffc001ffc000, KVADDR, "pgd page", 4096, (FOE), f41e90>
<read_proc_kcore: addr: ffffffc001ffc000 paddr: 2ffc000 cnt: 4096>
<readmem: ffffffc000ffe000, KVADDR, "pmd page", 4096, (FOE), f42ea0>
<read_proc_kcore: addr: ffffffc000ffe000 paddr: 1ffe000 cnt: 4096>
crash: seek error: kernel virtual address: ffffffc000ffe000 type: "pmd page"
root@odroid64-pre:~/crash-7.1.4#
Right, so as expected, it read the address of the first module structure
contained in the "modules" list_head, which is the first vmalloc()'d
address
that is read during crash initialization. It was in the act of doing a
page-table walkthough of virtual address of ffffffbffc081ad0, which crapped
out at the "pmd page" step. That's about as far as I can take it.
You'll
have to walk through the arm64_vtop_3level_4k() function in arm64.c.
Probably one of the various macros used in there doesn't match up with
your configuration.
Dave