[Bug dynamic-link/25905] New: VSX registers are corrupted during PLT resolution when glibc is built with --disable-multi-arch and --with-cpu=power9

[Bug dynamic-link/25905] New: VSX registers are corrupted during PLT resolution when glibc is built with --disable-multi-arch and --with-cpu=power9

[murphyp at linux dot vnet.ibm.com]

https://sourceware.org/bugzilla/show_bug.cgi?id=25905

            Bug ID: 25905
           Summary: VSX registers are corrupted during PLT resolution when
                    glibc is built with --disable-multi-arch and
                    --with-cpu=power9
           Product: glibc
           Version: 2.31
            Status: NEW
          Severity: normal
          Priority: P2
         Component: dynamic-link
          Assignee: unassigned at sourceware dot org
          Reporter: murphyp at linux dot vnet.ibm.com
  Target Milestone: ---

With the current tip of glibc, math/test-float64x-compat_totalordermag fails
the first test when glibc is built without multi-arch and with power9 baseline.

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[Bug dynamic-link/25905] VSX registers are corrupted during PLT resolution when glibc is built with --disable-multi-arch and --with-cpu=power9

[murphyp at linux dot vnet.ibm.com]

https://sourceware.org/bugzilla/show_bug.cgi?id=25905

Paul E. Murphy <murphyp at linux dot vnet.ibm.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Assignee|unassigned at sourceware dot org   |murphyp at linux dot vnet.ibm.com

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[Bug dynamic-link/25905] VSX registers are corrupted during PLT resolution when glibc is built with --disable-multi-arch and --with-cpu=power9

[murphyp at linux dot vnet.ibm.com]

https://sourceware.org/bugzilla/show_bug.cgi?id=25905

--- Comment #1 from Paul E. Murphy <murphyp at linux dot vnet.ibm.com> ---
glibc configured as such is using the ppc64le/power9 strcmp which uses vector
registers while resolving a function call (totalordermagf64x@GLIBC_2.27) which
passes arguments in vector regs.

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[Bug dynamic-link/25905] VSX registers are corrupted during PLT resolution when glibc is built with --disable-multi-arch and --with-cpu=power9

[tuliom at ascii dot art.br]

https://sourceware.org/bugzilla/show_bug.cgi?id=25905

Tulio Magno Quites Machado Filho <tuliom at ascii dot art.br> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |tuliom at ascii dot art.br

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[Bug dynamic-link/25905] VSX registers are corrupted during PLT resolution when glibc is built with --disable-multi-arch and --with-cpu=power9

[murphyp at linux dot vnet.ibm.com]

https://sourceware.org/bugzilla/show_bug.cgi?id=25905

--- Comment #2 from Paul E. Murphy <murphyp at linux dot vnet.ibm.com> ---
The culprit turns out to be the vector optimized power9 strcmp which is
clobbering volatile vector regs.  A patch has been submitted to workaround this
4a4db1de2f0fd936b583698dcc1b1c12a71828c8 in glibc 2.32.

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[Bug dynamic-link/25905] VSX registers are corrupted during PLT resolution when glibc is built with --disable-multi-arch and --with-cpu=power9

[murphyp at linux dot vnet.ibm.com]

https://sourceware.org/bugzilla/show_bug.cgi?id=25905

Paul E. Murphy <murphyp at linux dot vnet.ibm.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |2.32

--- Comment #3 from Paul E. Murphy <murphyp at linux dot vnet.ibm.com> ---
The culprit turns out to be the vector optimized power9 strcmp which is
clobbering volatile vector regs.  A patch has been submitted to workaround this
4a4db1de2f0fd936b583698dcc1b1c12a71828c8 in glibc 2.32.

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[Bug dynamic-link/25905] VSX registers are corrupted during PLT resolution when glibc is built with --disable-multi-arch and --with-cpu=power9

[tuliom at ascii dot art.br]

https://sourceware.org/bugzilla/show_bug.cgi?id=25905

Tulio Magno Quites Machado Filho <tuliom at ascii dot art.br> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |FIXED
             Status|NEW                         |RESOLVED

--- Comment #4 from Tulio Magno Quites Machado Filho <tuliom at ascii dot art.br> ---
As mentioned in the previous comment, this issue has been fixed with:

commit 4a4db1de2f0fd936b583698dcc1b1c12a71828c8
Author: Paul E. Murphy <murphyp@linux.vnet.ibm.com>
Date:   Fri May 1 14:30:42 2020 -0500

    powerpc64le/power9: guard power9 strcmp against rtld usage [BZ# 25905]

    strcmp is used while resolving PLT references.  Vector registers
    should not be used during this.  The P9 strcmp makes heavy use of
    vector registers, so it should be avoided in rtld.

    This prevents quiet vector register corruption when glibc is configured
    with --disable-multi-arch and --with-cpu=power9.  This can be seen with
    test-float64x-compat_totalordermag during the first call into
    totalordermagf64x@GLIBC_2.27.

    Add a guard to fallback to the power8 implementation when building
    power9 strcmp for libraries other than libc.

    Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

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