MFC r312455:

Use SRCTOP-relative paths and .CURDIR with :H instead of ".." specified paths

This implifies pathing in make/displayed output

MFC r292000: Remove historical GNUC test

The requirement is for a GCC-compatible compiler and not necessarily
GCC itself. However, we currently expect any compiler used for building
the whole of FreeBSD to be GCC-compatible and many things will break if
not; there's no longer a need to have an explicit test for this in csu.

MFC 257233: Use size of the MACHINE_ARCH string instead of sizeof(uint32_t).

Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Add an elf note on ARM to store the MACHINE_ARCH an executable was built
for. This is useful for software needing to know which architecture a
binary is built for as arm and armv6 have slight differences meaning only
some binaries build for one will work as expected on the other. It is
expected pkgng will be able to make use of this to simplify the logic to
determine which package ABI to use.

Approved by: re (kib)

Only assign the environ in the startup code when environ is NULL.
Preloaded library could have changed the environment, and
unconditional assingment to the environ undoes the customization.
The binaries needs to be recompiled to get the fix.

Move the common code to set up environ and __progname into the helper.
Note that ia64 possibly not fixed, due to it still using old csu.

Reported and tested by: John Hein <jhein@symmetricom.com>
Reviewed by: kan, scf
Approved by: secteam (simon)
MFC after: 2 weeks

After r217375, some startup objects under lib/csu are built in a special
way: first they are compiled to assembly, then some sed'ing is done on
the assembly, and lastly the assembly is compiled to an object file.

This last step is done using ${CC}, and not ${AS}, because when the
compiler is clang, it outputs directives that are too advanced for our
old gas. So we use clang's integrated assembler instead. (When the
compiler is gcc, it just calls gas, and nothing is different, except one
extra fork.)

However, in the .s to .o rules in lib/csu/$ARCH/Makefile, I still passed
CFLAGS to the compiler, instead of ACFLAGS, which are specifically for
compiling .s files.

In case you are using '-g' for debug info anywhere in your CFLAGS, it
causes the .s files to already contain debug information in the assembly
itself. In the next step, the .s files are also compiled using '-g',
and if the compiler is clang, it complains: "error: input can't have
.file dwarf directives when -g is used to generate dwarf debug info for
assembly code".

Fix this by using ${ACFLAGS} for compiling the .s files instead.

Reported by: jasone
MFC after: 1 week

Stop calling _init/_fini methods from crt1 for dynamic binaries. Do
call preinit, init and fini arrays methods from crt1 for static binaries.

Mark new crt1 with FreeBSD-specific ELF note.

Move some common crt1 code into new MI file ignore_init.c, to reduce
duplication. Also, conservatively adjust nearby sources for style.

Reviewed by: kan
Tested by: andrew (arm), flo (sparc64)
MFC after: 3 weeks

Apply a workaround for a binutils issue with the .note.ABI-tag section
generated from lib/csu/common/crtbrand.c (which ultimately ends up in
executables and shared libraries, via crt1.o, gcrt1.o or Scrt1.o).

For all arches except sparc, gcc emits the section directive for the
abitag struct in crtbrand.c with a PROGBITS type. However, newer
versions of binutils (after 2.16.90) require the section to be of NOTE
type, to guarantee that the .note.ABI-tag section correctly ends up in
the first page of the final executable.

Unfortunately, there is no clean way to tell gcc to use another section
type, so crtbrand.c (or the C files that include it) must be compiled in
multiple steps:

- Compile the .c file to a .s file.
- Edit the .s file to change the 'progbits' type to 'note', for the section
directive that defines the .note.ABI-tag section.
- Compile the .s file to an object file.

These steps are done in the invididual Makefiles for each applicable arch.

Reviewed by: kib

Let all .c and .S files under lib/csu consistently use the __FBSDID()
macro for identification, instead of several different hand-rolled
variants (plain .ident, .ascii, etc).

Use default WARNS setting (of 6) for lib/csu.

PR: bin/140089
Reviewed by: jmallett
Approved by: ed (co-mentor)

Properly declare non-extern functions in crt1

Also move the declarations after __progname consistently to
make the distinction clearer.

Reviewed by: jmallett
Approved by: ed (co-mentor)

Build lib/ with WARNS=6 by default.

Similar to libexec/, do the same with lib/. Make WARNS=6 the norm and
lower it when needed.

I'm setting WARNS?=0 for secure/. It seems secure/ includes the
Makefile.inc provided by lib/. I'm not going to touch that directory.
Most of the code there is contributed anyway.

Properly support -fPIE by linking PIE binaries with specially-built
Scrt1.o instead of crt1.o, since the later is built as non-PIC.

Separate i386-elf crt1.c into the pure assembler part and C code,
supplying all data extracted by assembler stub as explicit parameters [1].
Hide and localize _start1 symbol used as an interface between asm and
C code.

In collaboration with: kan
Inspired by: PR i386/127387 [1]
Prodded and tested by: rdivacky [1]
MFC after: 3 weeks

Implement .init and .fini.

Add support for TLS in statically linked programs.

C runtime support for FreeBSD/arm.