[Bug dynamic-link/27046] New: FAIL: elf/tst-glibc-hwcaps-prepend-cache

[Bug dynamic-link/27046] New: FAIL: elf/tst-glibc-hwcaps-prepend-cache

[schwab@linux-m68k.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=27046

            Bug ID: 27046
           Summary: FAIL: elf/tst-glibc-hwcaps-prepend-cache
           Product: glibc
           Version: 2.34
            Status: NEW
          Severity: normal
          Priority: P2
         Component: dynamic-link
          Assignee: unassigned at sourceware dot org
          Reporter: schwab@linux-m68k.org
  Target Milestone: ---
              Host: armv7l-*-*

tst-glibc-hwcaps-prepend-cache.c:109: numeric comparison failure
   left: 2 (0x2); from: marker1 ()
  right: 3 (0x3); from: 3
error: tst-glibc-hwcaps-prepend-cache.c:118: not true: dlopen (SONAME,
RTLD_NOW) == NULL
error: 2 test failures
running post-clean rsync

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[Bug dynamic-link/27046] FAIL: elf/tst-glibc-hwcaps-prepend-cache

[nsz at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=27046

Szabolcs Nagy <nsz at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |nsz at gcc dot gnu.org

--- Comment #1 from Szabolcs Nagy <nsz at gcc dot gnu.org> ---
i looked at this briefly (on arm), but could not figure it out:

under strace i see ldconfig writing out ld.so.cache that has
both the /prepend2/ and /prepend3/ libs, and the next dlopen
loads the /prepend2/ one based on the cache (does not search
the filesystem).

so it seems the cache lookup gets the ordering between
prepend2 and prepend3 wrong.

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[Bug dynamic-link/27046] FAIL: elf/tst-glibc-hwcaps-prepend-cache

[fweimer at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=27046

Florian Weimer <fweimer at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |fweimer at redhat dot com

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[Bug dynamic-link/27046] FAIL: elf/tst-glibc-hwcaps-prepend-cache

[fweimer at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=27046

--- Comment #2 from Florian Weimer <fweimer at redhat dot com> ---
What are your GCC and binutils versions?

I feel like I should debug this, but we haven't seen this in our armhfp builds,
so I don't know where to start.

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[Bug dynamic-link/27046] FAIL: elf/tst-glibc-hwcaps-prepend-cache

[nsz at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=27046

--- Comment #3 from Szabolcs Nagy <nsz at gcc dot gnu.org> ---
i ran this in a ubuntu 18.10 docker container with gcc 8.2.0 and binutils
2.31.1
(old armhf buildbot instance)

i will try it in a newer system.

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[Bug dynamic-link/27046] FAIL: elf/tst-glibc-hwcaps-prepend-cache

[schwab@linux-m68k.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=27046

--- Comment #4 from Andreas Schwab <schwab@linux-m68k.org> ---
https://build.opensuse.org/package/live_build_log/home:Andreas_Schwab:glibc/glibc:testsuite/a/armv7l

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[Bug dynamic-link/27046] FAIL: elf/tst-glibc-hwcaps-prepend-cache

[nsz at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=27046

--- Comment #5 from Szabolcs Nagy <nsz at gcc dot gnu.org> ---
reproducible on ubuntu 20.04 too with gcc-9.3.0 and binutils-2.34

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[Bug dynamic-link/27046] FAIL: elf/tst-glibc-hwcaps-prepend-cache

[nsz at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=27046

--- Comment #6 from Szabolcs Nagy <nsz at gcc dot gnu.org> ---
reproducible on ubuntu 20.04 with gcc-10.2.0 too

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[Bug dynamic-link/27046] FAIL: elf/tst-glibc-hwcaps-prepend-cache

[fweimer at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=27046

Florian Weimer <fweimer at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED
              Flags|                            |security-
           Assignee|unassigned at sourceware dot org   |fweimer at redhat dot com

--- Comment #7 from Florian Weimer <fweimer at redhat dot com> ---
This is caused by GLRO (dl_correct_cache_id) having the value 3, but ldconfig
writing a flags value of 0x903.

The integration of the best match processing for glibc-hwcaps with the best
match for flags is buggy.

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[Bug dynamic-link/27046] glibc-hwcaps priority matching fails on cache entry flags mismatch

[fweimer at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=27046

Florian Weimer <fweimer at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|FAIL:                       |glibc-hwcaps priority
                   |elf/tst-glibc-hwcaps-prepen |matching fails on cache
                   |d-cache                     |entry flags mismatch

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[Bug dynamic-link/27046] glibc-hwcaps priority matching fails on cache entry flags mismatch

[fweimer at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=27046

--- Comment #8 from Florian Weimer <fweimer at redhat dot com> ---
Patch posted: https://sourceware.org/pipermail/libc-alpha/2021-June/127862.html

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[Bug dynamic-link/27046] glibc-hwcaps priority matching fails on cache entry flags mismatch

[fweimer at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=27046

Florian Weimer <fweimer at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |FIXED
   Target Milestone|---                         |2.34
             Status|ASSIGNED                    |RESOLVED

--- Comment #9 from Florian Weimer <fweimer at redhat dot com> ---
Fixed for glibc 2.34 via:

commit 66db95b6e8264c5a6307f6a9e5285fec76907254
Author: Florian Weimer <fweimer@redhat.com>
Date:   Fri Jun 25 08:02:30 2021 +0200

    elf: Fix glibc-hwcaps priorities with cache flags mismatches [BZ #27046]

    If lib->flags (in the cache) did not match GLRO (dl_correct_cache_id),
    searching for further glibc-hwcaps entries did not happen, and it
    was possible that the best glibc-hwcaps was not found.  By accident,
    this causes a test failure for elf/tst-glibc-hwcaps-prepend-cache
    on armv7l.

    This commit changes the cache lookup logic to continue searching
    if (a) no match has been found, (b) a named glibc-hwcaps match
    has been found(), or (c) non-glibc-hwcaps match has been found
    and the entry flags and cache default flags do not match.

    _DL_CACHE_DEFAULT_ID is used instead of GLRO (dl_correct_cache_id)
    because the latter is only written once on i386 if loading
    of libc.so.5 libraries is selected, so GLRO (dl_correct_cache_id)
    should probably removed in a future change.

    Reviewed-by: Szabolcs Nagy <szabolcs.nagy@arm.com>

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