[Bug libc/19574] glibc should support building static PIE binaries

["hjl.tools at gmail dot com" <sourceware-bugzilla at sourceware dot org>]

https://sourceware.org/bugzilla/show_bug.cgi?id=19574

H.J. Lu <hjl.tools at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |2.27

--- Comment #1 from H.J. Lu <hjl.tools at gmail dot com> ---
I created hjl/pie/static branch to add a configure option, --enable-static-pie,
to built static PIE.  It works on i686 and x86-64 with binutils 2.29.  Static
PIE requires:

1. Target must support accessing of local functions without dynamic
relocations,
which is needed in start.S to call __libc_start_main with function addresses
of __libc_csu_init, __libc_csu_fini and main.  All functions in statice PIE
are local functions.
2. start.S is updated to check PIC instead SHARED for PIC code path and
avoid dynamic relocation, when PIC is defined and SHARED isn't defined,
to support static PIE.
3. All assembly codes are updated check PIC instead SHARED for PIC code
path to avoid dynamic relocations in read-only sections.
4. All assembly codes are updated check SHARED instead PIC for static
symbol name.
5. elf_machine_load_address in dl-machine.h are updated to support static
PIE.

NB: When glibc is built with GCC defaulted to PIE, libc.a is compiled
with -fPIE, regardless if --enable-static-pie is used to configure glibc.
When glibc is configured with --enable-static-pie, libc.a is compiled
with -fPIE, regardless wether GCC defaults to PIE or not.  The same libc.a
can be used to build both static executable and static PIE.  There is no
need for separate PIE copy of libc.a.
NB: When glibc is built with GCC defaulted to PIE, libc.a is compiled
with -fPIE, regardless if --enable-static-pie is used to configure glibc.
When glibc is configured with --enable-static-pie, libc.a is compiled
with -fPIE, regardless wether GCC defaults to PIE or not.  The same libc.a
can be used to build both static executable and static PIE.  There is no
need for separate PIE copy of libc.a.

Linker requirements to build glibc with --enable-static-pie:

1. Linker supports --no-dynamic-linker to remove PT_INTERP segment from
static PIE.
2. Linker can create working static PIE.  The x86-64 linker needs the
fix for

https://sourceware.org/bugzilla/show_bug.cgi?id=21782

Binutils 2.29 or above are OK for x86-64.  But linker status for other
targets need to be verified.

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