From: Brian Wang <brian.wang.0721@gmail.com>
To: musl@lists.openwall.com
Subject: Re: Difference between -O2 and -g
Date: Fri, 26 Oct 2012 10:47:57 +0800 [thread overview]
Message-ID: <CAPW=hRSaGV7ASBvbMg+WA5V-f=b5f09noUOHTg9hVV+95A264g@mail.gmail.com> (raw)
In-Reply-To: <20121026023254.GU254@brightrain.aerifal.cx>
On Fri, Oct 26, 2012 at 10:32 AM, Rich Felker <dalias@aerifal.cx> wrote:
> On Fri, Oct 26, 2012 at 10:04:46AM +0800, Brian Wang wrote:
>> > One very simple way to get a picture of what's going on in a program
>> > is to run it under strace. Try saving strace logs for both the working
>> > version and the broken version and comparing them either manually or
>> > with the diff utility (although the latter may be difficult unless you
>> > filter out the addresses and other contnets that will naturally
>> > differ, so it might be easier to visually inspect). If you don't
>> > already have an strace built for your target, I think Aboriginal Linux
>> > has static binaries you can use.
>>
>> I have previously built my static strace.
>> I could not decipher what went wrong. Please find the strace logs for
>> the three binaries in question.
>> The source code is basically the same, except for the musl ones,
>> printf calls are sprinkled here and there
>> as my desperate attempt.
>
> The good and bad traces diverge at this line, which only happens in
> the good one:
>
> writev(2, [{"CreateColormap : good end\n", 26}, {NULL, 0}], 2) = 26
>
> So search the source for that string and see what condition is causing
> that code to be reached or not reached.
Thank you for reading through them. :-)
The failed call (XaceHook) is:
-----------
/*
* Security creation/labeling check
*/
i = XaceHook(XACE_RESOURCE_ACCESS, clients[client], mid, RT_COLORMAP,
pmap, RT_NONE, NULL, DixCreateAccess);
if (i != Success) {
fprintf(stderr, "%s : 9\n", __func__);
FreeResource(mid, RT_NONE);
return i;
}
-----------
I got tired of lots of printfs. That is why I would like the help of
gdbserver.
However, with -O2 turned on, it is rather difficult to step through the code,
and without -O2, it will not go into the error path...
Are there any known alignment tricks that I should apply for ARM targets?
Thanks.
Brian
--
brian
------------------
Cool-Karaoke - The smallest recording studio, in your palm, open-sourced
http://cool-idea.com.tw/
iMaGiNaTiOn iS mOrE iMpOrTaNt tHaN kNoWlEdGe
next prev parent reply other threads:[~2012-10-26 2:47 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-10-26 1:31 Brian Wang
2012-10-26 1:40 ` Rich Felker
2012-10-26 2:04 ` Brian Wang
2012-10-26 2:21 ` Brian Wang
2012-10-26 2:32 ` Rich Felker
2012-10-26 2:47 ` Brian Wang [this message]
2012-10-26 2:55 ` Rich Felker
2012-10-26 3:01 ` Brian Wang
2012-10-26 3:19 ` Rich Felker
2012-10-26 6:44 ` Brian Wang
2012-10-26 17:58 ` Rich Felker
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