PR 54093: Align static TLS area to max_align_t.

branches: 1.2.44; 1.2.46;
Add PPC TLS support. Add -D_LIBC_SOURCE for tls.c and _lwp.c (powerpc)
so that __lwp_gettcb_fast and __lwp_settcb inlines are define.

Add TLS support infrastructure. For dynamic binaries, ld.elf_so exports
_rtld_tls_allocate and _rtld_tls_free. libpthread uses this functions to
setup the thread private area of all new threads. ld.elf_so is
responsible for setting up the private area for the initial thread.
Similar functions are called from _libc_init for static binaries, using
dl_iterate_phdr to access the ELF Program Header.

Add test cases to exercise the different TLS storage models. Test cases
are compiled and installed on all platforms, but are skipped on
platforms not marked for TLS support.

This material is based upon work partially supported by
The NetBSD Foundation under a contract with Joerg Sonnenberger.

It is inspired by the TLS support in FreeBSD by Doug Rabson and the
clean ups of the DragonFly port of the original FreeBSD modifications.

Create a new header lwp_private.h to contain _lwp_getprivate_fast,
_lwp_gettcb_fast, _lwp_settcb and remove them from mcontext.h, so that:
1. we don't need special hacks to hide them
2. we can include <lwp.h> where needed to get the necessary prototypes
without redefining them locally.

branches: 1.15.2;
Catch up with all the lint warnings since exit on warning was disabled.
Disable 'missing header declaration' and 'nested extern' warnings for now.

mmap MAP_FAILED audit.

Fix PR/54074 and PR/54093 completely.

More similar to the ld.elf_so logic, it is necessary to align with
p_align first. Also, invert the #ifdef condition for consistency.

Should fix regression for static linking binaries:
http://releng.netbsd.org/b5reports/sparc/commits-2019.11.html#2019.11.10.23.39.03
http://releng.netbsd.org/b5reports/sparc64/commits-2019.11.html#2019.11.16.04.10.33

Mirror the ld.elf_so logic for handling aligning the TLS size.
Most noticable, recompute the start of the TLS area for variant I
relative to the TCB. This makes a difference when the segment size and
base alignment don't agree.

Use alignof and not size_t for platforms with non-natural base
alignments.

PR 54093: Align static TLS area to max_align_t.

branches: 1.9.2;
Determine dynamic binaries by presence of PT_INTERP. Static PIE has
_DYNAMIC.

branches: 1.8.14; 1.8.16;
fix powerpc TLS problems by removing the hacks for PPC EABI.
the kernel no longer treats R2 specially and its use as
the TLS register is now handled entirely in userland.

branches: 1.7.4;
Put the startup code in .text.startup

branches: 1.6.4; 1.6.10;
Add a workaround for older crt0.o that overwrite r2 (tcb pointer).
(save tcb pointer using _lwp_setprivate in ld.elf_so and retrieve the tcb
via _lwp_getprivate in libc and use it to restore the value in r2).

It would be nice if lint knew that abort() will never return.
For now just insert a /* NOTREACHED */ comment to fix the build failure.

Appease the hppa linker.

Use __lwp_settcb if available.

Define namespace remap macros before including sys/tls.h.

Add TLS support infrastructure. For dynamic binaries, ld.elf_so exports
_rtld_tls_allocate and _rtld_tls_free. libpthread uses this functions to
setup the thread private area of all new threads. ld.elf_so is
responsible for setting up the private area for the initial thread.
Similar functions are called from _libc_init for static binaries, using
dl_iterate_phdr to access the ELF Program Header.

Add test cases to exercise the different TLS storage models. Test cases
are compiled and installed on all platforms, but are skipped on
platforms not marked for TLS support.

This material is based upon work partially supported by
The NetBSD Foundation under a contract with Joerg Sonnenberger.

It is inspired by the TLS support in FreeBSD by Doug Rabson and the
clean ups of the DragonFly port of the original FreeBSD modifications.