From: Chung-Lin Tang <chunglin_tang@mentor.com>
To: GNU C Library <libc-alpha@sourceware.org>
Subject: Ping x2 Re: [PATCH 1/2][RFC] #17645, fix slow DSO sorting behavior in dynamic loader
Date: Tue, 08 Oct 2019 06:22:00 -0000 [thread overview]
Message-ID: <8588322f-6391-7d6a-6b2e-f2cc05419622@mentor.com> (raw)
In-Reply-To: <2dea2558-c711-eab5-3728-be4986b7aad5@mentor.com>
Ping again.
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,
>> Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â // b depends on c (b,c linked to object a in fixed order)
>>
>> Â Â Â Â a->b->c;{+a;%a;-a}Â // a, b, c serially dependent, main program uses
>> Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â // dlopen/dlsym/dlclose on object a
>>
>> Â Â Â Â a->b->c;{}!->[abc]Â // a, b, c serially dependent; multiple tests generated
>> Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â // to test all permutations of a, b, c ordering linked
>> Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â // to main program
>>
>> Â Â Â (Above is just a short description of what the script can do, more
>> Â Â Â Â 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>
>>
>> Â Â Â Â Â Â Â Â [BZ #17645]
>> Â Â Â Â Â Â Â Â [BZ #15311]
>> Â Â Â Â Â Â Â Â [BZ #15310]
>> Â Â Â Â Â Â Â Â * elf/Makefile (test_dso_ordering): New make function.
>> Â Â Â Â Â Â Â Â (tst-dso-ordering[123456789]): Define new DSO sorting tests.
>> Â Â Â Â Â Â Â Â (tst-bz15311): Testcase from #15311.
>> Â Â Â Â Â Â Â Â * scripts/dso-ordering-test.py: New script.
next prev parent reply other threads:[~2019-10-08 6:22 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 ` Chung-Lin Tang [this message]
2019-10-08 17:41 ` Ping x2 " Adhemerval Zanella
2019-10-31 13:13 ` Carlos O'Donell
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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