2.36 pre-release

[Florian Weimer]

* Noah Goldstein:

> On Mon, Jul 25, 2022 at 9:42 PM Florian Weimer via Libc-alpha
> <libc-alpha@sourceware.org> wrote:
>>
>> * Paul Zimmermann:
>>
>> >        Dear Florian,
>> >
>> >> > on my i5-4590 with gcc 11.3.0, I get one failure when I configure with
>> >> > -march=native:
>> >> >
>> >> > Summary of test results:
>> >> >       1 FAIL
>> >> >    5084 PASS
>> >> >      77 UNSUPPORTED
>> >> >      18 XFAIL
>> >> >       4 XPASS
>> >> >
>> >> > FAIL: elf/tst-valgrind-smoke
>> >> >
>> >> > zimmerma@tomate:/localdisk/zimmerma/glibc/build-fma$ cat elf/tst-valgrind-smoke.out
>> >> > /usr/bin/valgrind
>> >> > /lib64/ld-linux-x86-64.so.2
>> >> > bin: /localdisk/zimmerma/glibc/build-fma/elf/valgrind-test
>> >> > ld.so: /localdisk/zimmerma/glibc/build-fma/elf/ld.so
>> >>
>> >> Would you please check if there is output to stderr, e.g. when running
>> >>
>> >>   make t=elf/tst-valgrind-smoke test
>> >>
>> >> ?  It's possible that valgrind does not support everything required by
>> >> -march=native.
>> >
>> > ok course, here you are:
>> >
>> > zimmerma@tomate:/localdisk/zimmerma/glibc/build-fma$  make t=elf/tst-valgrind-smoke test
>> > ...
>> > ==2457609== Conditional jump or move depends on uninitialised value(s)
>> > ==2457609==    at 0x12A118: strcmp (strcmp-avx2.S:462)
>> > ==2457609==    by 0x1125B4: _dl_name_match_p (dl-misc.c:69)
>> > ==2457609==    by 0x10FE43: _dl_map_object (dl-load.c:1971)
>> > ==2457609==    by 0x122124: map_doit (rtld.c:647)
>> > ==2457609==    by 0x11F8C5: _dl_catch_exception (dl-error-skeleton.c:208)
>> > ==2457609==    by 0x11F95E: _dl_catch_error (dl-error-skeleton.c:227)
>> > ==2457609==    by 0x12261E: do_preload (rtld.c:822)
>> > ==2457609==    by 0x12340F: handle_preload_list (rtld.c:898)
>> > ==2457609==    by 0x12630F: dl_main (rtld.c:1857)
>> > ==2457609==    by 0x1217BE: _dl_sysdep_start (dl-sysdep.c:140)
>> > ==2457609==    by 0x1231E1: _dl_start_final (rtld.c:497)
>> > ==2457609==    by 0x1231E1: _dl_start (rtld.c:584)
>> > ==2457609==    by 0x122007: ??? (in /localdisk/zimmerma/glibc/build-fma/elf/ld.so)
>> > ==2457609==
>>
>> I think we need more intercepts for ld.so, similar to what was added
>> here for strncmp:
>>
> Where would we add this in glibc?
>
>>   iconv_open causes ld.so v2.28 and later to execute optimised strncmp
>>   which confuses memcheck
>>   <https://bugs.kde.org/show_bug.cgi?id=434764>

Oops, sorry for being unclear.  It's a valgrind change, similar to the
one I referenced.

Thanks,
Florian