From: Adhemerval Zanella <adhemerval.zanella@linaro.org>
To: Jacob Kroon <jacob.kroon@gmail.com>,
Florian Weimer <fweimer@redhat.com>,
cltang@codesourcery.com
Cc: Jacob Kroon via Gdb <gdb@sourceware.org>
Subject: Re: Debugging ld.so in gdb
Date: Mon, 7 Feb 2022 10:53:12 -0300 [thread overview]
Message-ID: <639ee7e4-1bd8-0d34-af3c-4c33a20b8a8b@linaro.org> (raw)
In-Reply-To: <c9a8a265-e6c7-6bab-5c95-042da808f84f@gmail.com>
On 07/02/2022 10:45, Jacob Kroon wrote:
> On 2/7/22 14:39, Jacob Kroon wrote:
>> On 2/7/22 13:32, Jacob Kroon wrote:
>>> On 2/7/22 13:27, Florian Weimer wrote:
>>>> * Jacob Kroon:
>>>>
>>>>>> What I find really confusing is that this is not the result of a dlopen
>>>>>> call. I definitely would expect that the maps array contains *all*
>>>>>> objects that are being loaded. Clearly this is not the case here.
>>>>>> Somehow certain objects are missing, and then they get written into the
>>>>>> rpo array.
>>>>>>
>>>>>> Please try to find libjvm.so among the l_initfini arrays of the objects.
>>>>>
>>>>> I do find libjvm.so in a couple of the maps[]->l_initfini[]->l_name
>>>>> arrays, yes.
>>>>
>>>> Okay, and of course there is an assumption that those make it to the
>>>> maps. No wonder we run off the array.
>>>>
>>>>>> It must be present somewhere. I assume it's also on the main list,
>>>>>> which starts off at _rtld_global._dl_ns[0]._ns_loaded.
>>>>>
>>>>> Hmm how do I iterate over that data structure ?
>>>>>
>>>>> See below:
>>>>>> (gdb) print _rtld_global._dl_ns[0]._ns_loaded[0]->l_name
>>>>>> $186 = 0x7ffff7ff1d97 ""
>>>>>> (gdb) print _rtld_global._dl_ns[0]._ns_loaded[1]->l_name
>>>>>> $187 = 0x0
>>>>>> (gdb) print _rtld_global._dl_ns[0]._ns_loaded[2]->l_name
>>>>>> $188 = 0x0
>>>>>> (gdb) print _rtld_global._dl_ns[0]._ns_loaded->l_name
>>>>>> $189 = 0x7ffff7ff1d97 ""
>>>>>> (gdb) print _rtld_global._dl_ns[1]._ns_loaded->l_name
>>>>>> Cannot access memory at address 0x8
>>>>>> (gdb) print _rtld_global._dl_ns[2]._ns_loaded->l_name
>>>>>> Cannot access memory at address 0x8
>>>>
>>>> It's a list chained by l_prev/l_next.
>>>>
>>>
>>> Ok, yes "libjvm.so" is there, in multiple entries.
>>>
>>
>> I managed to build glibc master, and yes it also crashes. Reverting the
>> suspicious commit:
>>
>> commit 15a0c5730d1d5aeb95f50c9ec7470640084feae8
>> Author: Chung-Lin Tang <cltang@codesourcery.com>
>> Date: Thu Oct 21 21:41:22 2021 +0800
>>
>> elf: Fix slow DSO sorting behavior in dynamic loader (BZ #17645)
>>
>> fixes the crash. Adding a couple of more people.
>>
>
> And yes, using master (or host) glibc and running:
>
> $ GLIBC_TUNABLES="glibc.rtld.dynamic_sort=1" ldd mylib.so
>
> also works without crashing.
It is really hard to understand the issue you are seeing without the
context, since I was cced with a cropped thread. Could you send the
the full thread or the original issue?
next prev parent reply other threads:[~2022-02-07 13:53 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-04 13:45 Jacob Kroon
2022-02-04 13:58 ` Florian Weimer
2022-02-04 14:09 ` Jacob Kroon
2022-02-04 14:22 ` Florian Weimer
2022-02-04 14:27 ` Jacob Kroon
2022-02-04 16:09 ` Florian Weimer
2022-02-04 16:53 ` Jacob Kroon
2022-02-04 17:04 ` Florian Weimer
2022-02-04 17:11 ` Jacob Kroon
2022-02-04 17:15 ` Florian Weimer
2022-02-07 8:36 ` Jacob Kroon
2022-02-07 11:46 ` Jacob Kroon
2022-02-07 11:55 ` Florian Weimer
2022-02-07 12:15 ` Jacob Kroon
2022-02-07 12:27 ` Florian Weimer
2022-02-07 12:32 ` Jacob Kroon
2022-02-07 13:39 ` Jacob Kroon
2022-02-07 13:45 ` Jacob Kroon
2022-02-07 13:53 ` Adhemerval Zanella [this message]
2022-02-07 13:54 ` Jacob Kroon
2022-02-07 14:07 ` Florian Weimer
2022-02-07 16:28 ` Florian Weimer
2022-02-07 17:04 ` Jacob Kroon
2022-02-04 14:45 ` Jacob Kroon
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