[Crash-utility] crash doesn't decode regs with 7.1.5 (32-bit MIPS)

[Sagar Borikar]

On Thu, Oct 13, 2016 at 2:05 PM, Dave Anderson <anderson at redhat.com> wrote:
>
>
>
> ----- Original Message -----
>> Hi,
>>
>> I am facing issues with crash 7.1.5 for little endian mips CPU. Crash
>> is not able to decode the registers. But except registers all other
>> information is good. I tried to look at the notes section in the core
>> but doesn't seem anything wrong there. If I trace the vmcore with mips
>> gdb I can get the correct stack trace and register info.
>>
>> crash> i r
>> The program has no registers now.
>> gdb: gdb request failed: i r
>>
>> crash> bt
>> PID: 267    TASK: 808f66d0  CPU: 0   COMMAND: "sh"
>>
>
> Hi Sagar,
>
> The "i r" gdb command is not supported by the gdb embedded in the crash
> utility because it is invoked as "gdb vmlinux", and therefore it has no
> clue about any task or register set in a vmcore.

Thanks Dave.
I didn't quite get how to poke the registers from crash.  Can you give
me example?

> I don't know why the "bt" command is not working.  MIPS support was wholly
> written (and supported) by Rabin Vincent.  I've modified the subject line
> to indicate such, as well as cc'ing him directly.
>
> Dave

BTW, I have cross compiled gdb for mips and decoding regs and bt and
rest through that. Not sure whether the gdb in crash detect little
endian 32 bit mips vmcore.

Thanks
Sagar




>
>>
>> For the same vmcore, on gdb:
>>
>> (gdb) i r
>>           zero       at       v0       v1       a0       a1       a2       a3
>>  R0   00000000 004b376a 00000002 00000001 000024b0 0000000a ffffffff 00000002
>>             t0       t1       t2       t3       t4       t5       t6       t7
>>  R8   808f1180 00000000 00000001 77ab8000 7fd53050 004b4580 00000000 00000000
>>             s0       s1       s2       s3       s4       s5       s6       s7
>>  R16  00000002 808f0b80 808f1180 fffffff2 80d97f10 808f0b8c 00000030 00480000
>>             t8       t9       k0       k1       gp       sp       s8       ra
>>  R24  00000002 803b05bc 0000000a 81005890 80d94000 80d97e18 00000020 803b05e0
>>             sr       lo       hi      bad    cause       pc
>>       50808000 1100fc03 00000000 00000002 803b05e0 00000000
>>
>>
>> (gdb) bt
>> #0  0x00000000 in ?? ()
>> #1  0x803b05e0 in pcieport_sysfs_store (kobj=<optimized out>,
>> attr=<optimized out>, data=<optimized out>, len=<optimized out>) at
>> /build/sborikar/bodegadev/bodega-dev/mcpu/firmware/linux-4.4/drivers/cisco/pcieport/sysfs.c:59
>> #2  0x8021c6bc in kernfs_fop_write (file=<optimized out>,
>> user_buf=<optimized out>, count=<optimized out>, ppos=0x80d97f10) at
>> /build/sborikar/bodegadev/bodega-dev/mcpu/firmware/linux-4.4/fs/kernfs/file.c:312
>> #3  0x801c9020 in __vfs_write (file=0x24b0, p=<optimized out>,
>> count=<optimized out>, pos=<optimized out>) at
>> /build/sborikar/bodegadev/bodega-dev/mcpu/firmware/linux-4.4/fs/read_write.c:489
>> #4  0x801c9eac in vfs_write (file=0x83b187c0, buf=0xa <Address 0xa out
>> of bounds>, count=<optimized out>, pos=0x80d97f10) at
>> /build/sborikar/bodegadev/bodega-dev/mcpu/firmware/linux-4.4/fs/read_write.c:538
>> #5  0x801ca0dc in SYSC_write (count=<optimized out>, buf=<optimized
>> out>, fd=<optimized out>) at
>> /build/sborikar/bodegadev/bodega-dev/mcpu/firmware/linux-4.4/fs/read_write.c:585
>> #6  SyS_write (fd=<optimized out>, buf=<optimized out>,
>> count=<optimized out>) at
>> /build/sborikar/bodegadev/bodega-dev/mcpu/firmware/linux-4.4/fs/read_write.c:578
>> #7  0x8010e1dc in syscall_common () at
>> /build/sborikar/bodegadev/bodega-dev/mcpu/firmware/linux-4.4/arch/mips/kernel/scall32-o32.S:102
>>
>> Any idea?
>>
>> Thanks
>> Sagar
>>
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>>
>
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