Re: [PATCH v4 01/13] C-SKY: ABI related code

[Mao Han <han_mao at c-sky dot com>]

On Tue, Sep 11, 2018 at 09:15:19PM -0700, H.J. Lu wrote:
> On Tue, Sep 11, 2018 at 7:56 PM, Mao Han <han_mao@c-sky.com> wrote:
> > Codes in this patch contains lots of C-SKY ABI related code.  They are
> > written accroding to the registers assgnments, relocations, assemblly
> > described in C-SKY CPU ABI Standards and C-SKY architercure user guide.
> >
> > diff --git a/sysdeps/csky/abiv2/crti.S b/sysdeps/csky/abiv2/crti.S
> > new file mode 100644
> > index 0000000..4526a9e
> > --- /dev/null
> > +++ b/sysdeps/csky/abiv2/crti.S
> > @@ -0,0 +1,99 @@
> > +/* Special .init and .fini section support for C-SKY ABIV2.
> > +   Copyright (C) 2018 Free Software Foundation, Inc.
> > +   This file is part of the GNU C Library.
> > +
> > +   The GNU C Library is free software; you can redistribute it and/or
> > +   modify it under the terms of the GNU Lesser General Public
> > +   License as published by the Free Software Foundation; either
> > +   version 2.1 of the License, or (at your option) any later version.
> > +
> > +   In addition to the permissions in the GNU Lesser General Public
> > +   License, the Free Software Foundation gives you unlimited
> > +   permission to link the compiled version of this file with other
> > +   programs, and to distribute those programs without any restriction
> > +   coming from the use of this file. (The GNU Lesser General Public
> > +   License restrictions do apply in other respects; for example, they
> > +   cover modification of the file, and distribution when not linked
> > +   into another program.)
> > +
> > +   Note that people who make modified versions of this file are not
> > +   obligated to grant this special exception for their modified
> > +   versions; it is their choice whether to do so. The GNU Lesser
> > +   General Public License gives permission to release a modified
> > +   version without this exception; this exception also makes it
> > +   possible to release a modified version which carries forward this
> > +   exception.
> > +
> > +   The GNU C Library is distributed in the hope that it will be useful,
> > +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> > +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> > +   Lesser General Public License for more details.
> > +
> > +   You should have received a copy of the GNU Lesser General Public
> > +   License along with the GNU C Library.  If not, see
> > +   <http://www.gnu.org/licenses/>.  */
> > +
> > +/* crti.S puts a function prologue at the beginning of the .init and
> > +   .fini sections and defines global symbols for those addresses, so
> > +   they can be called as functions.  The symbols _init and _fini are
> > +   magic and cause the linker to emit DT_INIT and DT_FINI.  */
> > +
> > +#include <libc-symbols.h>
> > +#include <sysdep.h>
> > +
> > +#ifndef PREINIT_FUNCTION
> > +# define PREINIT_FUNCTION __gmon_start__
> > +#endif
> > +
> > +#ifndef PREINIT_FUNCTION_WEAK
> > +# define PREINIT_FUNCTION_WEAK 1
> > +#endif
> > +
> > +#if PREINIT_FUNCTION_WEAK
> > +       weak_extern (PREINIT_FUNCTION)
> > +#else
> > +       .hidden PREINIT_FUNCTION
> > +#endif
> > +
> > +       .section .init,"ax",@progbits
> > +       .align 4
> > +       .globl _init
> > +       .hidden _init
> 
> Does C-SKY really need _init and _fini?
> 
> 
> -- 
> H.J.

It seems used to call some pre-init function for libc, register transactional
memory clone tables and invoke global constructors on C-SKY. Althrough I 
haven't found any constructors call by _init, I just tend to have _init and
_fini as most other arch have these.

Han Mao