[Bug libbacktrace/114941] New: libbacktrace build is broken for FDPIC uclibc targets by gcc-14-5173-g2b64e4a54042

[Bug libbacktrace/114941] New: libbacktrace build is broken for FDPIC uclibc targets by gcc-14-5173-g2b64e4a54042

[jcmvbkbc at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114941

            Bug ID: 114941
           Summary: libbacktrace build is broken for FDPIC uclibc targets
                    by gcc-14-5173-g2b64e4a54042
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libbacktrace
          Assignee: unassigned at gcc dot gnu.org
          Reporter: jcmvbkbc at gcc dot gnu.org
                CC: ian at gcc dot gnu.org
  Target Milestone: ---

A fix for the https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111315 turned on the
use of the dl_iterate_phdr interface in the libbacktrace, but since the type of
the dl_phdr_info::dlpi_addr on FDPIC targets using uclibc is not compatible
with uintptr_t the libstdc++-v3 build breaks for these targets with the
following message:

elf.c:7372:62: error: incompatible type for argument 6 of ‘elf_add’
 7372 |   if (elf_add (pd->state, filename, descriptor, NULL, 0,
info->dlpi_addr,
      |                                                         
~~~~^~~~~~~~~~~
      |                                                              |
      |                                                              struct
elf32_fdpic_loadaddr
elf.c:6504:20: note: expected ‘uintptr_t’ {aka ‘unsigned int’} but argument is
of type ‘struct elf32_fdpic_loadaddr’

[Bug libbacktrace/114941] libbacktrace build is broken for FDPIC uclibc targets by r14-5173-g2b64e4a54042

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114941

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
So a patch like what was done in r0-56719-g34208acf14fa02 needs to be done to
libbacktrace . Basically this has always been broken.

[Bug libbacktrace/114941] libbacktrace build is broken for FDPIC uclibc targets by r14-5173-g2b64e4a54042

[ian at airs dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114941

Ian Lance Taylor <ian at airs dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |ian at airs dot com

--- Comment #2 from Ian Lance Taylor <ian at airs dot com> ---
What is the correct way to get the address at which the shared library was
loaded when using FDPIC?

[Bug libbacktrace/114941] libbacktrace build is broken for FDPIC uclibc targets by r14-5173-g2b64e4a54042

[jcmvbkbc at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114941

--- Comment #3 from jcmvbkbc at gcc dot gnu.org ---
(In reply to Ian Lance Taylor from comment #2)
> What is the correct way to get the address at which the shared library was
> loaded when using FDPIC?

There's no single base address in case of FDPIC, the macro __RELOC_POINTER(ptr,
loadaddr) can be used with the elf32_fdpic_loadaddr::dlpi_addr as the last
argument to translate an address according to the load map. An example is
available in the libgcc/unwind-dw2-fde-dip.c

[Bug libbacktrace/114941] libbacktrace build is broken for FDPIC uclibc targets by r14-5173-g2b64e4a54042

[jcmvbkbc at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114941

--- Comment #4 from jcmvbkbc at gcc dot gnu.org ---
Proposed fix:

https://gcc.gnu.org/pipermail/gcc-patches/2024-May/652798.html