From: Carlos O'Donell <carlos@redhat.com>
To: cltang@codesourcery.com, GNU C Library <libc-alpha@sourceware.org>
Subject: Re: Ping x2 Re: [PATCH 1/2][RFC] #17645, fix slow DSO sorting behavior in dynamic loader
Date: Thu, 31 Oct 2019 13:13:00 -0000 [thread overview]
Message-ID: <55008c83-b935-c1b0-1166-2df97d1715b6@redhat.com> (raw)
In-Reply-To: <8588322f-6391-7d6a-6b2e-f2cc05419622@mentor.com>
On 10/8/19 2:22 AM, Chung-Lin Tang wrote:
> Ping again.
I have these applied and I'm putting this through testing.
> On 2019/9/17 5:55 PM, Chung-Lin Tang wrote:
>> Ping?
>>
>> On 2019/7/21 1:50 AM, Chung-Lin Tang wrote:
>>> Hi, this patch is our attempt at resolving the slow shared object sorting
>>> situation in #17645, #15310, and some effort at #15311. I realize this is
>>> pretty unsuitable timing to be submitting a patch of such nature now (probably
>>> way too late to be included into 2.30), but still sending now anyways as this
>>> will probably need quite some discussion before being approved.
>>>
>>> Prior attempts at solving this slow sorting behavior appeared to have failed
>>> due to inadequate proposed testing, therefore cannot convince reviewers to
>>> touch what seems to be perceived as a sensitive and easy to break part of ld.so.
>>>
>>> Therefore the first part of this patch is not a change to the dynamic loader
>>> code proper, but a testing framework for constructing DSO sorting tests.
>>> It consists of a new Python script 'dso-ordering-test.py' that serves to
>>> generate both testcase source files and the needed Makefile fragments from
>>> a short description string, for example:
>>>
>>> a->b->c->d // four objects linked one after another
>>>
>>> a->[bc]->d;b->c // a depends on b and c, which both depend on d,
>>> // b depends on c (b,c linked to object a in fixed order)
>>>
>>> a->b->c;{+a;%a;-a} // a, b, c serially dependent, main program uses
>>> // dlopen/dlsym/dlclose on object a
>>>
>>> a->b->c;{}!->[abc] // a, b, c serially dependent; multiple tests generated
>>> // to test all permutations of a, b, c ordering linked
>>> // to main program
>>>
>>> (Above is just a short description of what the script can do, more
>>> documentation is in the script comments.)
>>>
>>> and, a patch to glibc/elf/Makefile which uses this script to add a few
>>> DSO sorting testcases. The description string notation and output form of the
>>> generated testcases is short enough that both the test descriptions
>>> and expected outcomes can all directly be specified in the Makefile.
>>>
>>> In terms of the tests I added using this script, I am not completely sure they are
>>> (together with existing tests) adequate to prove algorithmic integrity in face
>>> of any ld.so code changes, but the script should provide a solid tool to further
>>> improve on coverage. Also welcome suggestions if the current features are still
>>> lacking in expressing some case of shared object relations, or if the documentation
>>> still feels unclear.
>>>
>>> Thanks,
>>> Chung-Lin
>>>
>>> 2019-07-20 Chung-Lin Tang <cltang@codesourcery.com>
>>>
>>> [BZ #17645]
>>> [BZ #15311]
>>> [BZ #15310]
>>> * elf/Makefile (test_dso_ordering): New make function.
>>> (tst-dso-ordering[123456789]): Define new DSO sorting tests.
>>> (tst-bz15311): Testcase from #15311.
>>> * scripts/dso-ordering-test.py: New script.
--
Cheers,
Carlos.
next prev parent reply other threads:[~2019-10-31 13:13 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-20 17:51 Chung-Lin Tang
2019-07-23 13:21 ` Florian Weimer
2019-07-25 18:46 ` Chung-Lin Tang
2019-07-29 9:48 ` Florian Weimer
2019-08-05 10:39 ` Chung-Lin Tang
2019-08-05 10:45 ` Florian Weimer
2019-08-10 11:49 ` Chung-Lin Tang
2019-09-17 9:55 ` Ping " Chung-Lin Tang
2019-10-08 6:22 ` Ping x2 " Chung-Lin Tang
2019-10-08 17:41 ` Adhemerval Zanella
2019-10-31 13:13 ` Carlos O'Donell [this message]
2019-11-14 9:58 ` Chung-Lin Tang
2019-11-25 9:19 ` Chung-Lin Tang
2019-11-25 19:08 ` Carlos O'Donell
2019-11-26 8:19 ` Chung-Lin Tang
2019-11-27 15:20 ` Carlos O'Donell
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