[Crash-utility] [PATCH] crash extension: trace

[d.hatayama at fujitsu.com]

Wengang,

Thanks for your patch.

> >From a UEK5 vmcore, I see that

What arch and kernel version do you use?
What is the last kernel version you didn't see this issue?

I need to identify the change in the kernel side that caused this issue.

> 
> crash> p &__start___trace_bprintk_fmt
> $1 = (const char *(*)[]) 0xffffffffa163f1d0
> crash> p &__stop___trace_bprintk_fmt
> $2 = (const char *(*)[]) 0xffffffffa163f1f0
> 
> so (0xffffffffa163f1f0 - 0xffffffffa163f1d0)/8 = 4.
> 
> there are two zero addresses at index 2 and 3.
> crash> rd __start___trace_bprintk_fmt 4
> ffffffffa163f1d0:  ffffffffa11ccdca ffffffffa11ccdca   ................
> ffffffffa163f1e0:  0000000000000000 0000000000000000   ................
> 
> current implementation will fail (no output for trace show command)
> on seeing the zero addresses.
> 
> fix: ignore zero addresses in add_print_address.
> 
> tested to be good (compared the ftrace log from vmcore and that from live system).
> 
> Signed-off-by: Wengang Wang <wen.gang.wang at oracle.com>

Thanks.
HATAYAMA, Daisuke