freebsd-skq/lib/csu/common/crtbrand.c
Dimitry Andric 9ef4e3afcb 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
2011-01-13 20:44:31 +00:00

70 lines
2.7 KiB
C

/*-
* Copyright 2000 David E. O'Brien, John D. Polstra.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/param.h>
#define ABI_VENDOR "FreeBSD"
#define ABI_SECTION ".note.ABI-tag"
#define ABI_NOTETYPE 1
/*
* Special ".note" entry specifying the ABI version. See
* http://www.netbsd.org/Documentation/kernel/elf-notes.html
* for more information.
*
* For all arches except sparc, gcc emits the section directive for the
* following struct 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 this C file (or the C file that includes 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.
*/
static const struct {
int32_t namesz;
int32_t descsz;
int32_t type;
char name[sizeof ABI_VENDOR];
int32_t desc;
} abitag __attribute__ ((section (ABI_SECTION), aligned(4))) __used = {
sizeof ABI_VENDOR,
sizeof(int32_t),
ABI_NOTETYPE,
ABI_VENDOR,
__FreeBSD_version
};