Thanks Dave.
I found one more issue with a somewhat "corrupt" vmcore. In this case it is
ARM-specific in unwind_arm.c, so maybe Mika will also look at it.
In the case I am investigating I get a readmem error while reading the unwind
tables. The way unwinding currently is implemented Crash then stops and no
further analysis is possible. When I patched Crash to continue anyhow, every
command I tried worked nicely including bt, so there is no reason to stop at
this kind of problem.
When investigating further I found that the problem occurs in
init_module_unwind_tables. It is in the call to do_list(&ld) that the readmem
error is found. I also looked in the code for do_list and saw that it could be
configured to return even if errors were found, by setting ld.flags.
/*
* Iterate through unwind table list and store start address of each
* table in table_list.
*/
ld.flags += RETURN_ON_LIST_ERROR; /* added line */
hq_open();
cnt = do_list(&ld);
if (cnt == -1) { /* added if statement, 3 lines */
return FALSE;
}
table_list = (ulong *)GETBUF(cnt * sizeof(ulong));
cnt = retrieve_list(table_list, cnt);
hq_close();
By adding the lines indicated above I get an appropriate warning that the
unwind tables cannot be read, and then Crash works as usual.
Jan
Jan Karlsson
Senior Software Engineer
MIB
Sony Mobile Communications
Tel: +46703062174
sonymobile.com
-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Dave Anderson
Sent: torsdag den 26 april 2012 15:09
To: Discussion list for crash utility usage, maintenance and development
Cc: Fänge, Thomas
Subject: Re: [Crash-utility] loop in crash
----- Original Message -----
> Hi
>
> and thanks for your work with this problem.
>
> As you expected crash silently just loops and I spotted the problem
> by turning on debug printouts.
> If I include printouts for the "cache" address, the first value seems
> reasonable, but then it starts to repeat with the value 0x00000001.
> Last, your patch solves the problem nicely. I get a warning about
> duplicate kmem_slab entry and crash continues to execute and issues
> other warnings indicating a corrupt vmcore file.
>
> Jan
OK good -- I should have hq_xxx()'d that loop a long time ago.
Queued for crash-6.0.6.
Thanks,
Dave
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