[Bug math/30305] New: Incorrect asm constraint in feraiseexcept on x86-64

[Bug math/30305] New: Incorrect asm constraint in feraiseexcept on x86-64

[fweimer at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=30305

            Bug ID: 30305
           Summary: Incorrect asm constraint in feraiseexcept on x86-64
           Product: glibc
           Version: 2.38
            Status: NEW
          Severity: normal
          Priority: P2
         Component: math
          Assignee: unassigned at sourceware dot org
          Reporter: fweimer at redhat dot com
  Target Milestone: ---
            Target: x86_64-linux-gnu
             Flags: security-

It's been reported that the old sysdeps/x86/fpu/bits/fenv.h implementation has
incorrect asm constraints because they not reflect that divss clobbers its
output argument. This has been fixed in with the removal of the inline
implementation in this commit:

commit 4a30b6109c119feeb95cf154382057fbf757d4da
Author: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Date:   Mon Mar 9 10:21:51 2020 -0300

    x86: Remove feraiseexcept optimization

    Similar to fenvinline.h removal, this kind of optimization is better
    implemented by the compiler.  Also newer code avoid setting exceptions
    directly (for instance the code to make new logf, log2f and powf
    implementatation to now support SVID compat).

    The BZ#94194 [1] the corresponding GCC bug for adding replacements
    for these on x86.

    Checked on x86_64-linux-gnu and i686-linux-gnu.

    [1] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94194

However, the out-of-line implementation in sysdeps/x86_64/fpu/fraiseexcpt.c
seems to have the same bug.

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[Bug math/30305] Incorrect asm constraint in feraiseexcept on x86-64

[fweimer at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=30305

Florian Weimer <fweimer at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |fweimer at redhat dot com
           See Also|                            |https://bugzilla.redhat.com
                   |                            |/show_bug.cgi?id=2183081

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[Bug math/30305] Incorrect asm constraint in feraiseexcept on x86-64

[fweimer at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=30305

Florian Weimer <fweimer at redhat dot com> changed:

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

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[Bug math/30305] Incorrect asm constraint in feraiseexcept on x86-64

[fweimer at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=30305

--- Comment #1 from Florian Weimer <fweimer at redhat dot com> ---
Patch posted:

[PATCH] x86_64: Fix asm constraints in feraiseexcept (bug 30305)
<https://sourceware.org/pipermail/libc-alpha/2023-April/146914.html>

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[Bug math/30305] Incorrect asm constraint in feraiseexcept on x86-64

[fweimer at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=30305

Florian Weimer <fweimer at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
   Target Milestone|---                         |2.38
         Resolution|---                         |FIXED

--- Comment #2 from Florian Weimer <fweimer at redhat dot com> ---
Fixed for 2.38 via:

commit 5d1ccdda7b0c625751661d50977f3dfbc73f8eae
Author: Florian Weimer <fweimer@redhat.com>
Date:   Mon Apr 3 17:23:11 2023 +0200

    x86_64: Fix asm constraints in feraiseexcept (bug 30305)

    The divss instruction clobbers its first argument, and the constraints
    need to reflect that.  Fortunately, with GCC 12, generated code does
    not actually change, so there is no externally visible bug.

    Suggested-by: Jakub Jelinek <jakub@redhat.com>
    Reviewed-by: Noah Goldstein <goldstein.w.n@gmail.com>

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