[Bug dynamic-link/31640] New: POWER10 ld.so crashes in elf_machine_load_address with GCC 14

[Bug dynamic-link/31640] New: POWER10 ld.so crashes in elf_machine_load_address with GCC 14

[fweimer at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=31640

            Bug ID: 31640
           Summary: POWER10 ld.so crashes in elf_machine_load_address with
                    GCC 14
           Product: glibc
           Version: 2.40
            Status: NEW
          Severity: normal
          Priority: P2
         Component: dynamic-link
          Assignee: fweimer at redhat dot com
          Reporter: fweimer at redhat dot com
                CC: bergner at linux dot ibm.com
  Target Milestone: ---
            Target: powerpc64le-linux-gnu

When built with GCC 14, ld.so crashes in elf_machine_load_address because the
current implementation assumes that r2 still has the kernel-provided value:

static inline Elf64_Addr
elf_machine_load_address (void)
{
  Elf64_Addr ret;

  /* The first entry in .got (and thus the first entry in .toc) is the
     link-time TOC_base, ie. r2.  So the difference between that and
     the current r2 set by the kernel is how far the shared lib has
     moved.  */
  asm ( "       ld      %0,-32768(2)\n"
        "       subf    %0,%0,2\n"
        : "=r"  (ret));
  return ret;
}

I don't think that's necessarily true in PCREL mode, so this is a glibc bug.

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[Bug dynamic-link/31640] POWER10 ld.so crashes in elf_machine_load_address with GCC 14

[fweimer at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=31640

Florian Weimer <fweimer at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED
                 CC|                            |fweimer at redhat dot com
              Flags|                            |security-

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[Bug dynamic-link/31640] POWER10 ld.so crashes in elf_machine_load_address with GCC 14

[fweimer at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=31640

Florian Weimer <fweimer at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
   Target Milestone|---                         |2.40
         Resolution|---                         |FIXED

--- Comment #1 from Florian Weimer <fweimer at redhat dot com> ---
Fixed for 2.40 via:

commit 14e56bd4ce15ac2d1cc43f762eb2e6b83fec1afe
Author: Florian Weimer <fweimer@redhat.com>
Date:   Sun Apr 14 08:24:51 2024 +0200

    powerpc: Fix ld.so address determination for PCREL mode (bug 31640)

    This seems to have stopped working with some GCC 14 versions,
    which clobber r2.  With other compilers, the kernel-provided
    r2 value is still available at this point.

    Reviewed-by: Peter Bergner <bergner@linux.ibm.com>

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