[Bug nptl/15687] New: powerpc64 abi breakage with nocancel functions

[Bug nptl/15687] New: powerpc64 abi breakage with nocancel functions

[amodra at gmail dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=15687

            Bug ID: 15687
           Summary: powerpc64 abi breakage with nocancel functions
           Product: glibc
           Version: 2.18
            Status: NEW
          Severity: normal
          Priority: P2
         Component: nptl
          Assignee: unassigned at sourceware dot org
          Reporter: amodra at gmail dot com
                CC: drepper.fsp at gmail dot com

glibc contains powerpc64 functions without functions descriptors.  As seen in
nptl/ptw-pause.o

[snip]
  [ 1] .text     PROGBITS    0000000000000000 000040 0000b4 00  AX  0   0  4
[snip]
  [ 5] .opd      PROGBITS    0000000000000000 0000f8 000018 00  WA  0   0  8
[snip]
    10: 0000000000000000   180 FUNC    GLOBAL DEFAULT    5 __libc_pause
    11: 000000000000000c    48 FUNC    GLOBAL DEFAULT    1 __pause_nocancel

Notice that __pause_nocancel is define in .text, ie. does not have a function
descriptor.  This triggered an error in powerpc64 gold --gc-sections.

It looks to me like
nptl/sysdeps/unix/sysv/linux/powerpc/powerpc64/sysdep-cancel.h is the culprit. 
The ENTRY macro normally is reposible for generating function descriptors, but
I see no such thing for the nocancel variant entry point.

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[Bug nptl/15687] powerpc64 abi breakage with nocancel functions

[schwab@linux-m68k.org]

http://sourceware.org/bugzilla/show_bug.cgi?id=15687

--- Comment #1 from Andreas Schwab <schwab@linux-m68k.org> ---
All _nocancel decls are hidden anyway, so I don't think this is a problem. 
None of the calls need the descriptor.

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[Bug nptl/15687] powerpc64 abi breakage with nocancel functions

[amodra at gmail dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=15687

--- Comment #2 from Alan Modra <amodra at gmail dot com> ---
They might be hidden in libc.so, but not in the static library.

nm libc.a | grep __pause_nocancel
000000000000000c T __pause_nocancel

You would not be able to set a function pointer to any of these functions, then
call via the pointer.  Not that anyone is likely to want to do such a thing, 
I'm just pointing out one of the consequences of no function descriptor.

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[Bug nptl/15687] powerpc64 abi breakage with nocancel functions

[schwab@linux-m68k.org]

http://sourceware.org/bugzilla/show_bug.cgi?id=15687

--- Comment #3 from Andreas Schwab <schwab@linux-m68k.org> ---
Well, the static library has a lot of internal things that are not supposed to
be used, and break if used improperly.

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[Bug nptl/15687] powerpc64 abi breakage with nocancel functions

[jingyuuiuc at gmail dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=15687

Jing Yu <jingyuuiuc at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jingyuuiuc at gmail dot com

--- Comment #4 from Jing Yu <jingyuuiuc at gmail dot com> ---
__pause_nocancel is called by __pthread_mutex_lock_full(pthread_mutex_t*) in
nptl/pthread_mutex_lock.c. In such a case, does __pause_nocancel need a
function descriptor?

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[Bug nptl/15687] powerpc64 abi breakage with nocancel functions

[schwab@linux-m68k.org]

http://sourceware.org/bugzilla/show_bug.cgi?id=15687

--- Comment #5 from Andreas Schwab <schwab@linux-m68k.org> ---
The reference is still library-internal.

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[Bug nptl/15687] powerpc64 abi breakage with nocancel functions

[amodra at gmail dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=15687

Alan Modra <amodra at gmail dot com> changed:

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

--- Comment #6 from Alan Modra <amodra at gmail dot com> ---
Closing since these are reserved identifiers.

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[Bug nptl/15687] powerpc64 abi breakage with nocancel functions

[fweimer at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=15687

Florian Weimer <fweimer at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
              Flags|                            |security-

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